diff --git a/documentation/dev-manual/bmaptool.rst b/documentation/dev-manual/bmaptool.rst new file mode 100644 index 0000000000..9add72cf3b --- /dev/null +++ b/documentation/dev-manual/bmaptool.rst @@ -0,0 +1,59 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Flashing Images Using ``bmaptool`` +********************************** + +A fast and easy way to flash an image to a bootable device is to use +Bmaptool, which is integrated into the OpenEmbedded build system. +Bmaptool is a generic tool that creates a file's block map (bmap) and +then uses that map to copy the file. As compared to traditional tools +such as dd or cp, Bmaptool can copy (or flash) large files like raw +system image files much faster. + +.. note:: + + - If you are using Ubuntu or Debian distributions, you can install + the ``bmap-tools`` package using the following command and then + use the tool without specifying ``PATH`` even from the root + account:: + + $ sudo apt install bmap-tools + + - If you are unable to install the ``bmap-tools`` package, you will + need to build Bmaptool before using it. Use the following command:: + + $ bitbake bmap-tools-native + +Following, is an example that shows how to flash a Wic image. Realize +that while this example uses a Wic image, you can use Bmaptool to flash +any type of image. Use these steps to flash an image using Bmaptool: + +#. *Update your local.conf File:* You need to have the following set + in your ``local.conf`` file before building your image:: + + IMAGE_FSTYPES += "wic wic.bmap" + +#. *Get Your Image:* Either have your image ready (pre-built with the + :term:`IMAGE_FSTYPES` + setting previously mentioned) or take the step to build the image:: + + $ bitbake image + +#. *Flash the Device:* Flash the device with the image by using Bmaptool + depending on your particular setup. The following commands assume the + image resides in the :term:`Build Directory`'s ``deploy/images/`` area: + + - If you have write access to the media, use this command form:: + + $ oe-run-native bmap-tools-native bmaptool copy build-directory/tmp/deploy/images/machine/image.wic /dev/sdX + + - If you do not have write access to the media, set your permissions + first and then use the same command form:: + + $ sudo chmod 666 /dev/sdX + $ oe-run-native bmap-tools-native bmaptool copy build-directory/tmp/deploy/images/machine/image.wic /dev/sdX + +For help on the ``bmaptool`` command, use the following command:: + + $ bmaptool --help + diff --git a/documentation/dev-manual/build-quality.rst b/documentation/dev-manual/build-quality.rst new file mode 100644 index 0000000000..713ea3a48e --- /dev/null +++ b/documentation/dev-manual/build-quality.rst @@ -0,0 +1,409 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Maintaining Build Output Quality +******************************** + +Many factors can influence the quality of a build. For example, if you +upgrade a recipe to use a new version of an upstream software package or +you experiment with some new configuration options, subtle changes can +occur that you might not detect until later. Consider the case where +your recipe is using a newer version of an upstream package. In this +case, a new version of a piece of software might introduce an optional +dependency on another library, which is auto-detected. If that library +has already been built when the software is building, the software will +link to the built library and that library will be pulled into your +image along with the new software even if you did not want the library. + +The :ref:`ref-classes-buildhistory` class helps you maintain the quality of +your build output. You can use the class to highlight unexpected and possibly +unwanted changes in the build output. When you enable build history, it records +information about the contents of each package and image and then commits that +information to a local Git repository where you can examine the information. + +The remainder of this section describes the following: + +- :ref:`How you can enable and disable build history ` + +- :ref:`How to understand what the build history contains ` + +- :ref:`How to limit the information used for build history ` + +- :ref:`How to examine the build history from both a command-line and web interface ` + +Enabling and Disabling Build History +==================================== + +Build history is disabled by default. To enable it, add the following +:term:`INHERIT` statement and set the :term:`BUILDHISTORY_COMMIT` variable to +"1" at the end of your ``conf/local.conf`` file found in the +:term:`Build Directory`:: + + INHERIT += "buildhistory" + BUILDHISTORY_COMMIT = "1" + +Enabling build history as +previously described causes the OpenEmbedded build system to collect +build output information and commit it as a single commit to a local +:ref:`overview-manual/development-environment:git` repository. + +.. note:: + + Enabling build history increases your build times slightly, + particularly for images, and increases the amount of disk space used + during the build. + +You can disable build history by removing the previous statements from +your ``conf/local.conf`` file. + +Understanding What the Build History Contains +============================================= + +Build history information is kept in ``${``\ :term:`TOPDIR`\ ``}/buildhistory`` +in the :term:`Build Directory` as defined by the :term:`BUILDHISTORY_DIR` +variable. Here is an example abbreviated listing: + +.. image:: figures/buildhistory.png + :align: center + :width: 50% + +At the top level, there is a ``metadata-revs`` file that lists the +revisions of the repositories for the enabled layers when the build was +produced. The rest of the data splits into separate ``packages``, +``images`` and ``sdk`` directories, the contents of which are described +as follows. + +Build History Package Information +--------------------------------- + +The history for each package contains a text file that has name-value +pairs with information about the package. For example, +``buildhistory/packages/i586-poky-linux/busybox/busybox/latest`` +contains the following: + +.. code-block:: none + + PV = 1.22.1 + PR = r32 + RPROVIDES = + RDEPENDS = glibc (>= 2.20) update-alternatives-opkg + RRECOMMENDS = busybox-syslog busybox-udhcpc update-rc.d + PKGSIZE = 540168 + FILES = /usr/bin/* /usr/sbin/* /usr/lib/busybox/* /usr/lib/lib*.so.* \ + /etc /com /var /bin/* /sbin/* /lib/*.so.* /lib/udev/rules.d \ + /usr/lib/udev/rules.d /usr/share/busybox /usr/lib/busybox/* \ + /usr/share/pixmaps /usr/share/applications /usr/share/idl \ + /usr/share/omf /usr/share/sounds /usr/lib/bonobo/servers + FILELIST = /bin/busybox /bin/busybox.nosuid /bin/busybox.suid /bin/sh \ + /etc/busybox.links.nosuid /etc/busybox.links.suid + +Most of these +name-value pairs correspond to variables used to produce the package. +The exceptions are ``FILELIST``, which is the actual list of files in +the package, and ``PKGSIZE``, which is the total size of files in the +package in bytes. + +There is also a file that corresponds to the recipe from which the package +came (e.g. ``buildhistory/packages/i586-poky-linux/busybox/latest``): + +.. code-block:: none + + PV = 1.22.1 + PR = r32 + DEPENDS = initscripts kern-tools-native update-rc.d-native \ + virtual/i586-poky-linux-compilerlibs virtual/i586-poky-linux-gcc \ + virtual/libc virtual/update-alternatives + PACKAGES = busybox-ptest busybox-httpd busybox-udhcpd busybox-udhcpc \ + busybox-syslog busybox-mdev busybox-hwclock busybox-dbg \ + busybox-staticdev busybox-dev busybox-doc busybox-locale busybox + +Finally, for those recipes fetched from a version control system (e.g., +Git), there is a file that lists source revisions that are specified in +the recipe and the actual revisions used during the build. Listed +and actual revisions might differ when +:term:`SRCREV` is set to +${:term:`AUTOREV`}. Here is an +example assuming +``buildhistory/packages/qemux86-poky-linux/linux-yocto/latest_srcrev``):: + + # SRCREV_machine = "38cd560d5022ed2dbd1ab0dca9642e47c98a0aa1" + SRCREV_machine = "38cd560d5022ed2dbd1ab0dca9642e47c98a0aa1" + # SRCREV_meta = "a227f20eff056e511d504b2e490f3774ab260d6f" + SRCREV_meta ="a227f20eff056e511d504b2e490f3774ab260d6f" + +You can use the +``buildhistory-collect-srcrevs`` command with the ``-a`` option to +collect the stored :term:`SRCREV` values from build history and report them +in a format suitable for use in global configuration (e.g., +``local.conf`` or a distro include file) to override floating +:term:`AUTOREV` values to a fixed set of revisions. Here is some example +output from this command:: + + $ buildhistory-collect-srcrevs -a + # all-poky-linux + SRCREV:pn-ca-certificates = "07de54fdcc5806bde549e1edf60738c6bccf50e8" + SRCREV:pn-update-rc.d = "8636cf478d426b568c1be11dbd9346f67e03adac" + # core2-64-poky-linux + SRCREV:pn-binutils = "87d4632d36323091e731eb07b8aa65f90293da66" + SRCREV:pn-btrfs-tools = "8ad326b2f28c044cb6ed9016d7c3285e23b673c8" + SRCREV_bzip2-tests:pn-bzip2 = "f9061c030a25de5b6829e1abf373057309c734c0" + SRCREV:pn-e2fsprogs = "02540dedd3ddc52c6ae8aaa8a95ce75c3f8be1c0" + SRCREV:pn-file = "504206e53a89fd6eed71aeaf878aa3512418eab1" + SRCREV_glibc:pn-glibc = "24962427071fa532c3c48c918e9d64d719cc8a6c" + SRCREV:pn-gnome-desktop-testing = "e346cd4ed2e2102c9b195b614f3c642d23f5f6e7" + SRCREV:pn-init-system-helpers = "dbd9197569c0935029acd5c9b02b84c68fd937ee" + SRCREV:pn-kmod = "b6ecfc916a17eab8f93be5b09f4e4f845aabd3d1" + SRCREV:pn-libnsl2 = "82245c0c58add79a8e34ab0917358217a70e5100" + SRCREV:pn-libseccomp = "57357d2741a3b3d3e8425889a6b79a130e0fa2f3" + SRCREV:pn-libxcrypt = "50cf2b6dd4fdf04309445f2eec8de7051d953abf" + SRCREV:pn-ncurses = "51d0fd9cc3edb975f04224f29f777f8f448e8ced" + SRCREV:pn-procps = "19a508ea121c0c4ac6d0224575a036de745eaaf8" + SRCREV:pn-psmisc = "5fab6b7ab385080f1db725d6803136ec1841a15f" + SRCREV:pn-ptest-runner = "bcb82804daa8f725b6add259dcef2067e61a75aa" + SRCREV:pn-shared-mime-info = "18e558fa1c8b90b86757ade09a4ba4d6a6cf8f70" + SRCREV:pn-zstd = "e47e674cd09583ff0503f0f6defd6d23d8b718d3" + # qemux86_64-poky-linux + SRCREV_machine:pn-linux-yocto = "20301aeb1a64164b72bc72af58802b315e025c9c" + SRCREV_meta:pn-linux-yocto = "2d38a472b21ae343707c8bd64ac68a9eaca066a0" + # x86_64-linux + SRCREV:pn-binutils-cross-x86_64 = "87d4632d36323091e731eb07b8aa65f90293da66" + SRCREV_glibc:pn-cross-localedef-native = "24962427071fa532c3c48c918e9d64d719cc8a6c" + SRCREV_localedef:pn-cross-localedef-native = "794da69788cbf9bf57b59a852f9f11307663fa87" + SRCREV:pn-debianutils-native = "de14223e5bffe15e374a441302c528ffc1cbed57" + SRCREV:pn-libmodulemd-native = "ee80309bc766d781a144e6879419b29f444d94eb" + SRCREV:pn-virglrenderer-native = "363915595e05fb252e70d6514be2f0c0b5ca312b" + SRCREV:pn-zstd-native = "e47e674cd09583ff0503f0f6defd6d23d8b718d3" + +.. note:: + + Here are some notes on using the ``buildhistory-collect-srcrevs`` command: + + - By default, only values where the :term:`SRCREV` was not hardcoded + (usually when :term:`AUTOREV` is used) are reported. Use the ``-a`` + option to see all :term:`SRCREV` values. + + - The output statements might not have any effect if overrides are + applied elsewhere in the build system configuration. Use the + ``-f`` option to add the ``forcevariable`` override to each output + line if you need to work around this restriction. + + - The script does apply special handling when building for multiple + machines. However, the script does place a comment before each set + of values that specifies which triplet to which they belong as + previously shown (e.g., ``i586-poky-linux``). + +Build History Image Information +------------------------------- + +The files produced for each image are as follows: + +- ``image-files:`` A directory containing selected files from the root + filesystem. The files are defined by + :term:`BUILDHISTORY_IMAGE_FILES`. + +- ``build-id.txt:`` Human-readable information about the build + configuration and metadata source revisions. This file contains the + full build header as printed by BitBake. + +- ``*.dot:`` Dependency graphs for the image that are compatible with + ``graphviz``. + +- ``files-in-image.txt:`` A list of files in the image with + permissions, owner, group, size, and symlink information. + +- ``image-info.txt:`` A text file containing name-value pairs with + information about the image. See the following listing example for + more information. + +- ``installed-package-names.txt:`` A list of installed packages by name + only. + +- ``installed-package-sizes.txt:`` A list of installed packages ordered + by size. + +- ``installed-packages.txt:`` A list of installed packages with full + package filenames. + +.. note:: + + Installed package information is able to be gathered and produced + even if package management is disabled for the final image. + +Here is an example of ``image-info.txt``: + +.. code-block:: none + + DISTRO = poky + DISTRO_VERSION = 3.4+snapshot-a0245d7be08f3d24ea1875e9f8872aa6bbff93be + USER_CLASSES = buildstats + IMAGE_CLASSES = qemuboot qemuboot license_image + IMAGE_FEATURES = debug-tweaks + IMAGE_LINGUAS = + IMAGE_INSTALL = packagegroup-core-boot speex speexdsp + BAD_RECOMMENDATIONS = + NO_RECOMMENDATIONS = + PACKAGE_EXCLUDE = + ROOTFS_POSTPROCESS_COMMAND = write_package_manifest; license_create_manifest; cve_check_write_rootfs_manifest; ssh_allow_empty_password; ssh_allow_root_login; postinst_enable_logging; rootfs_update_timestamp; write_image_test_data; empty_var_volatile; sort_passwd; rootfs_reproducible; + IMAGE_POSTPROCESS_COMMAND = buildhistory_get_imageinfo ; + IMAGESIZE = 9265 + +Other than ``IMAGESIZE``, +which is the total size of the files in the image in Kbytes, the +name-value pairs are variables that may have influenced the content of +the image. This information is often useful when you are trying to +determine why a change in the package or file listings has occurred. + +Using Build History to Gather Image Information Only +---------------------------------------------------- + +As you can see, build history produces image information, including +dependency graphs, so you can see why something was pulled into the +image. If you are just interested in this information and not interested +in collecting specific package or SDK information, you can enable +writing only image information without any history by adding the +following to your ``conf/local.conf`` file found in the +:term:`Build Directory`:: + + INHERIT += "buildhistory" + BUILDHISTORY_COMMIT = "0" + BUILDHISTORY_FEATURES = "image" + +Here, you set the +:term:`BUILDHISTORY_FEATURES` +variable to use the image feature only. + +Build History SDK Information +----------------------------- + +Build history collects similar information on the contents of SDKs (e.g. +``bitbake -c populate_sdk imagename``) as compared to information it +collects for images. Furthermore, this information differs depending on +whether an extensible or standard SDK is being produced. + +The following list shows the files produced for SDKs: + +- ``files-in-sdk.txt:`` A list of files in the SDK with permissions, + owner, group, size, and symlink information. This list includes both + the host and target parts of the SDK. + +- ``sdk-info.txt:`` A text file containing name-value pairs with + information about the SDK. See the following listing example for more + information. + +- ``sstate-task-sizes.txt:`` A text file containing name-value pairs + with information about task group sizes (e.g. :ref:`ref-tasks-populate_sysroot` + tasks have a total size). The ``sstate-task-sizes.txt`` file exists + only when an extensible SDK is created. + +- ``sstate-package-sizes.txt:`` A text file containing name-value pairs + with information for the shared-state packages and sizes in the SDK. + The ``sstate-package-sizes.txt`` file exists only when an extensible + SDK is created. + +- ``sdk-files:`` A folder that contains copies of the files mentioned + in ``BUILDHISTORY_SDK_FILES`` if the files are present in the output. + Additionally, the default value of ``BUILDHISTORY_SDK_FILES`` is + specific to the extensible SDK although you can set it differently if + you would like to pull in specific files from the standard SDK. + + The default files are ``conf/local.conf``, ``conf/bblayers.conf``, + ``conf/auto.conf``, ``conf/locked-sigs.inc``, and + ``conf/devtool.conf``. Thus, for an extensible SDK, these files get + copied into the ``sdk-files`` directory. + +- The following information appears under each of the ``host`` and + ``target`` directories for the portions of the SDK that run on the + host and on the target, respectively: + + .. note:: + + The following files for the most part are empty when producing an + extensible SDK because this type of SDK is not constructed from + packages as is the standard SDK. + + - ``depends.dot:`` Dependency graph for the SDK that is compatible + with ``graphviz``. + + - ``installed-package-names.txt:`` A list of installed packages by + name only. + + - ``installed-package-sizes.txt:`` A list of installed packages + ordered by size. + + - ``installed-packages.txt:`` A list of installed packages with full + package filenames. + +Here is an example of ``sdk-info.txt``: + +.. code-block:: none + + DISTRO = poky + DISTRO_VERSION = 1.3+snapshot-20130327 + SDK_NAME = poky-glibc-i686-arm + SDK_VERSION = 1.3+snapshot + SDKMACHINE = + SDKIMAGE_FEATURES = dev-pkgs dbg-pkgs + BAD_RECOMMENDATIONS = + SDKSIZE = 352712 + +Other than ``SDKSIZE``, which is +the total size of the files in the SDK in Kbytes, the name-value pairs +are variables that might have influenced the content of the SDK. This +information is often useful when you are trying to determine why a +change in the package or file listings has occurred. + +Examining Build History Information +----------------------------------- + +You can examine build history output from the command line or from a web +interface. + +To see any changes that have occurred (assuming you have +:term:`BUILDHISTORY_COMMIT` = "1"), +you can simply use any Git command that allows you to view the history +of a repository. Here is one method:: + + $ git log -p + +You need to realize, +however, that this method does show changes that are not significant +(e.g. a package's size changing by a few bytes). + +There is a command-line tool called ``buildhistory-diff``, though, +that queries the Git repository and prints just the differences that +might be significant in human-readable form. Here is an example:: + + $ poky/poky/scripts/buildhistory-diff . HEAD^ + Changes to images/qemux86_64/glibc/core-image-minimal (files-in-image.txt): + /etc/anotherpkg.conf was added + /sbin/anotherpkg was added + * (installed-package-names.txt): + * anotherpkg was added + Changes to images/qemux86_64/glibc/core-image-minimal (installed-package-names.txt): + anotherpkg was added + packages/qemux86_64-poky-linux/v86d: PACKAGES: added "v86d-extras" + * PR changed from "r0" to "r1" + * PV changed from "0.1.10" to "0.1.12" + packages/qemux86_64-poky-linux/v86d/v86d: PKGSIZE changed from 110579 to 144381 (+30%) + * PR changed from "r0" to "r1" + * PV changed from "0.1.10" to "0.1.12" + +.. note:: + + The ``buildhistory-diff`` tool requires the ``GitPython`` + package. Be sure to install it using Pip3 as follows:: + + $ pip3 install GitPython --user + + + Alternatively, you can install ``python3-git`` using the appropriate + distribution package manager (e.g. ``apt``, ``dnf``, or ``zipper``). + +To see changes to the build history using a web interface, follow the +instruction in the ``README`` file +:yocto_git:`here `. + +Here is a sample screenshot of the interface: + +.. image:: figures/buildhistory-web.png + :width: 100% + diff --git a/documentation/dev-manual/building.rst b/documentation/dev-manual/building.rst new file mode 100644 index 0000000000..a395793493 --- /dev/null +++ b/documentation/dev-manual/building.rst @@ -0,0 +1,939 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Building +******** + +This section describes various build procedures, such as the steps +needed for a simple build, building a target for multiple configurations, +generating an image for more than one machine, and so forth. + +Building a Simple Image +======================= + +In the development environment, you need to build an image whenever you +change hardware support, add or change system libraries, or add or +change services that have dependencies. There are several methods that allow +you to build an image within the Yocto Project. This section presents +the basic steps you need to build a simple image using BitBake from a +build host running Linux. + +.. note:: + + - For information on how to build an image using + :term:`Toaster`, see the + :doc:`/toaster-manual/index`. + + - For information on how to use ``devtool`` to build images, see the + ":ref:`sdk-manual/extensible:using \`\`devtool\`\` in your sdk workflow`" + section in the Yocto Project Application Development and the + Extensible Software Development Kit (eSDK) manual. + + - For a quick example on how to build an image using the + OpenEmbedded build system, see the + :doc:`/brief-yoctoprojectqs/index` document. + +The build process creates an entire Linux distribution from source and +places it in your :term:`Build Directory` under ``tmp/deploy/images``. For +detailed information on the build process using BitBake, see the +":ref:`overview-manual/concepts:images`" section in the Yocto Project Overview +and Concepts Manual. + +The following figure and list overviews the build process: + +.. image:: figures/bitbake-build-flow.png + :width: 100% + +#. *Set up Your Host Development System to Support Development Using the + Yocto Project*: See the ":doc:`start`" section for options on how to get a + build host ready to use the Yocto Project. + +#. *Initialize the Build Environment:* Initialize the build environment + by sourcing the build environment script (i.e. + :ref:`structure-core-script`):: + + $ source oe-init-build-env [build_dir] + + When you use the initialization script, the OpenEmbedded build system + uses ``build`` as the default :term:`Build Directory` in your current work + directory. You can use a `build_dir` argument with the script to + specify a different :term:`Build Directory`. + + .. note:: + + A common practice is to use a different :term:`Build Directory` for + different targets; for example, ``~/build/x86`` for a ``qemux86`` + target, and ``~/build/arm`` for a ``qemuarm`` target. In any + event, it's typically cleaner to locate the :term:`Build Directory` + somewhere outside of your source directory. + +#. *Make Sure Your* ``local.conf`` *File is Correct*: Ensure the + ``conf/local.conf`` configuration file, which is found in the + :term:`Build Directory`, is set up how you want it. This file defines many + aspects of the build environment including the target machine architecture + through the :term:`MACHINE` variable, the packaging format used during + the build (:term:`PACKAGE_CLASSES`), and a centralized tarball download + directory through the :term:`DL_DIR` variable. + +#. *Build the Image:* Build the image using the ``bitbake`` command:: + + $ bitbake target + + .. note:: + + For information on BitBake, see the :doc:`bitbake:index`. + + The target is the name of the recipe you want to build. Common + targets are the images in ``meta/recipes-core/images``, + ``meta/recipes-sato/images``, and so forth all found in the + :term:`Source Directory`. Alternatively, the target + can be the name of a recipe for a specific piece of software such as + BusyBox. For more details about the images the OpenEmbedded build + system supports, see the + ":ref:`ref-manual/images:Images`" chapter in the Yocto + Project Reference Manual. + + As an example, the following command builds the + ``core-image-minimal`` image:: + + $ bitbake core-image-minimal + + Once an + image has been built, it often needs to be installed. The images and + kernels built by the OpenEmbedded build system are placed in the + :term:`Build Directory` in ``tmp/deploy/images``. For information on how to + run pre-built images such as ``qemux86`` and ``qemuarm``, see the + :doc:`/sdk-manual/index` manual. For + information about how to install these images, see the documentation + for your particular board or machine. + +Building Images for Multiple Targets Using Multiple Configurations +================================================================== + +You can use a single ``bitbake`` command to build multiple images or +packages for different targets where each image or package requires a +different configuration (multiple configuration builds). The builds, in +this scenario, are sometimes referred to as "multiconfigs", and this +section uses that term throughout. + +This section describes how to set up for multiple configuration builds +and how to account for cross-build dependencies between the +multiconfigs. + +Setting Up and Running a Multiple Configuration Build +----------------------------------------------------- + +To accomplish a multiple configuration build, you must define each +target's configuration separately using a parallel configuration file in +the :term:`Build Directory` or configuration directory within a layer, and you +must follow a required file hierarchy. Additionally, you must enable the +multiple configuration builds in your ``local.conf`` file. + +Follow these steps to set up and execute multiple configuration builds: + +- *Create Separate Configuration Files*: You need to create a single + configuration file for each build target (each multiconfig). + The configuration definitions are implementation dependent but often + each configuration file will define the machine and the + temporary directory BitBake uses for the build. Whether the same + temporary directory (:term:`TMPDIR`) can be shared will depend on what is + similar and what is different between the configurations. Multiple MACHINE + targets can share the same (:term:`TMPDIR`) as long as the rest of the + configuration is the same, multiple :term:`DISTRO` settings would need separate + (:term:`TMPDIR`) directories. + + For example, consider a scenario with two different multiconfigs for the same + :term:`MACHINE`: "qemux86" built + for two distributions such as "poky" and "poky-lsb". In this case, + you would need to use the different :term:`TMPDIR`. + + Here is an example showing the minimal statements needed in a + configuration file for a "qemux86" target whose temporary build + directory is ``tmpmultix86``:: + + MACHINE = "qemux86" + TMPDIR = "${TOPDIR}/tmpmultix86" + + The location for these multiconfig configuration files is specific. + They must reside in the current :term:`Build Directory` in a sub-directory of + ``conf`` named ``multiconfig`` or within a layer's ``conf`` directory + under a directory named ``multiconfig``. Following is an example that defines + two configuration files for the "x86" and "arm" multiconfigs: + + .. image:: figures/multiconfig_files.png + :align: center + :width: 50% + + The usual :term:`BBPATH` search path is used to locate multiconfig files in + a similar way to other conf files. + +- *Add the BitBake Multi-configuration Variable to the Local + Configuration File*: Use the + :term:`BBMULTICONFIG` + variable in your ``conf/local.conf`` configuration file to specify + each multiconfig. Continuing with the example from the previous + figure, the :term:`BBMULTICONFIG` variable needs to enable two + multiconfigs: "x86" and "arm" by specifying each configuration file:: + + BBMULTICONFIG = "x86 arm" + + .. note:: + + A "default" configuration already exists by definition. This + configuration is named: "" (i.e. empty string) and is defined by + the variables coming from your ``local.conf`` + file. Consequently, the previous example actually adds two + additional configurations to your build: "arm" and "x86" along + with "". + +- *Launch BitBake*: Use the following BitBake command form to launch + the multiple configuration build:: + + $ bitbake [mc:multiconfigname:]target [[[mc:multiconfigname:]target] ... ] + + For the example in this section, the following command applies:: + + $ bitbake mc:x86:core-image-minimal mc:arm:core-image-sato mc::core-image-base + + The previous BitBake command builds a ``core-image-minimal`` image + that is configured through the ``x86.conf`` configuration file, a + ``core-image-sato`` image that is configured through the ``arm.conf`` + configuration file and a ``core-image-base`` that is configured + through your ``local.conf`` configuration file. + +.. note:: + + Support for multiple configuration builds in the Yocto Project &DISTRO; + (&DISTRO_NAME;) Release does not include Shared State (sstate) + optimizations. Consequently, if a build uses the same object twice + in, for example, two different :term:`TMPDIR` + directories, the build either loads from an existing sstate cache for + that build at the start or builds the object fresh. + +Enabling Multiple Configuration Build Dependencies +-------------------------------------------------- + +Sometimes dependencies can exist between targets (multiconfigs) in a +multiple configuration build. For example, suppose that in order to +build a ``core-image-sato`` image for an "x86" multiconfig, the root +filesystem of an "arm" multiconfig must exist. This dependency is +essentially that the +:ref:`ref-tasks-image` task in the +``core-image-sato`` recipe depends on the completion of the +:ref:`ref-tasks-rootfs` task of the +``core-image-minimal`` recipe. + +To enable dependencies in a multiple configuration build, you must +declare the dependencies in the recipe using the following statement +form:: + + task_or_package[mcdepends] = "mc:from_multiconfig:to_multiconfig:recipe_name:task_on_which_to_depend" + +To better show how to use this statement, consider the example scenario +from the first paragraph of this section. The following statement needs +to be added to the recipe that builds the ``core-image-sato`` image:: + + do_image[mcdepends] = "mc:x86:arm:core-image-minimal:do_rootfs" + +In this example, the `from_multiconfig` is "x86". The `to_multiconfig` is "arm". The +task on which the :ref:`ref-tasks-image` task in the recipe depends is the +:ref:`ref-tasks-rootfs` task from the ``core-image-minimal`` recipe associated +with the "arm" multiconfig. + +Once you set up this dependency, you can build the "x86" multiconfig +using a BitBake command as follows:: + + $ bitbake mc:x86:core-image-sato + +This command executes all the tasks needed to create the +``core-image-sato`` image for the "x86" multiconfig. Because of the +dependency, BitBake also executes through the :ref:`ref-tasks-rootfs` task for the +"arm" multiconfig build. + +Having a recipe depend on the root filesystem of another build might not +seem that useful. Consider this change to the statement in the +``core-image-sato`` recipe:: + + do_image[mcdepends] = "mc:x86:arm:core-image-minimal:do_image" + +In this case, BitBake must +create the ``core-image-minimal`` image for the "arm" build since the +"x86" build depends on it. + +Because "x86" and "arm" are enabled for multiple configuration builds +and have separate configuration files, BitBake places the artifacts for +each build in the respective temporary build directories (i.e. +:term:`TMPDIR`). + +Building an Initial RAM Filesystem (Initramfs) Image +==================================================== + +An initial RAM filesystem (:term:`Initramfs`) image provides a temporary root +filesystem used for early system initialization, typically providing tools and +loading modules needed to locate and mount the final root filesystem. + +Follow these steps to create an :term:`Initramfs` image: + +#. *Create the Initramfs Image Recipe:* You can reference the + ``core-image-minimal-initramfs.bb`` recipe found in the + ``meta/recipes-core`` directory of the :term:`Source Directory` + as an example from which to work. + +#. *Decide if You Need to Bundle the Initramfs Image Into the Kernel + Image:* If you want the :term:`Initramfs` image that is built to be bundled + in with the kernel image, set the :term:`INITRAMFS_IMAGE_BUNDLE` + variable to ``"1"`` in your ``local.conf`` configuration file and set the + :term:`INITRAMFS_IMAGE` variable in the recipe that builds the kernel image. + + Setting the :term:`INITRAMFS_IMAGE_BUNDLE` flag causes the :term:`Initramfs` + image to be unpacked into the ``${B}/usr/`` directory. The unpacked + :term:`Initramfs` image is then passed to the kernel's ``Makefile`` using the + :term:`CONFIG_INITRAMFS_SOURCE` variable, allowing the :term:`Initramfs` + image to be built into the kernel normally. + +#. *Optionally Add Items to the Initramfs Image Through the Initramfs + Image Recipe:* If you add items to the :term:`Initramfs` image by way of its + recipe, you should use :term:`PACKAGE_INSTALL` rather than + :term:`IMAGE_INSTALL`. :term:`PACKAGE_INSTALL` gives more direct control of + what is added to the image as compared to the defaults you might not + necessarily want that are set by the :ref:`ref-classes-image` + or :ref:`ref-classes-core-image` classes. + +#. *Build the Kernel Image and the Initramfs Image:* Build your kernel + image using BitBake. Because the :term:`Initramfs` image recipe is a + dependency of the kernel image, the :term:`Initramfs` image is built as well + and bundled with the kernel image if you used the + :term:`INITRAMFS_IMAGE_BUNDLE` variable described earlier. + +Bundling an Initramfs Image From a Separate Multiconfig +------------------------------------------------------- + +There may be a case where we want to build an :term:`Initramfs` image which does not +inherit the same distro policy as our main image, for example, we may want +our main image to use ``TCLIBC="glibc"``, but to use ``TCLIBC="musl"`` in our :term:`Initramfs` +image to keep a smaller footprint. However, by performing the steps mentioned +above the :term:`Initramfs` image will inherit ``TCLIBC="glibc"`` without allowing us +to override it. + +To achieve this, you need to perform some additional steps: + +#. *Create a multiconfig for your Initramfs image:* You can perform the steps + on ":ref:`dev-manual/building:building images for multiple targets using multiple configurations`" to create a separate multiconfig. + For the sake of simplicity let's assume such multiconfig is called: ``initramfscfg.conf`` and + contains the variables:: + + TMPDIR="${TOPDIR}/tmp-initramfscfg" + TCLIBC="musl" + +#. *Set additional Initramfs variables on your main configuration:* + Additionally, on your main configuration (``local.conf``) you need to set the + variables:: + + INITRAMFS_MULTICONFIG = "initramfscfg" + INITRAMFS_DEPLOY_DIR_IMAGE = "${TOPDIR}/tmp-initramfscfg/deploy/images/${MACHINE}" + + The variables :term:`INITRAMFS_MULTICONFIG` and :term:`INITRAMFS_DEPLOY_DIR_IMAGE` + are used to create a multiconfig dependency from the kernel to the :term:`INITRAMFS_IMAGE` + to be built coming from the ``initramfscfg`` multiconfig, and to let the + buildsystem know where the :term:`INITRAMFS_IMAGE` will be located. + + Building a system with such configuration will build the kernel using the + main configuration but the :ref:`ref-tasks-bundle_initramfs` task will grab the + selected :term:`INITRAMFS_IMAGE` from :term:`INITRAMFS_DEPLOY_DIR_IMAGE` + instead, resulting in a musl based :term:`Initramfs` image bundled in the kernel + but a glibc based main image. + + The same is applicable to avoid inheriting :term:`DISTRO_FEATURES` on :term:`INITRAMFS_IMAGE` + or to build a different :term:`DISTRO` for it such as ``poky-tiny``. + + +Building a Tiny System +====================== + +Very small distributions have some significant advantages such as +requiring less on-die or in-package memory (cheaper), better performance +through efficient cache usage, lower power requirements due to less +memory, faster boot times, and reduced development overhead. Some +real-world examples where a very small distribution gives you distinct +advantages are digital cameras, medical devices, and small headless +systems. + +This section presents information that shows you how you can trim your +distribution to even smaller sizes than the ``poky-tiny`` distribution, +which is around 5 Mbytes, that can be built out-of-the-box using the +Yocto Project. + +Tiny System Overview +-------------------- + +The following list presents the overall steps you need to consider and +perform to create distributions with smaller root filesystems, achieve +faster boot times, maintain your critical functionality, and avoid +initial RAM disks: + +- :ref:`Determine your goals and guiding principles + ` + +- :ref:`dev-manual/building:understand what contributes to your image size` + +- :ref:`Reduce the size of the root filesystem + ` + +- :ref:`Reduce the size of the kernel ` + +- :ref:`dev-manual/building:remove package management requirements` + +- :ref:`dev-manual/building:look for other ways to minimize size` + +- :ref:`dev-manual/building:iterate on the process` + +Goals and Guiding Principles +---------------------------- + +Before you can reach your destination, you need to know where you are +going. Here is an example list that you can use as a guide when creating +very small distributions: + +- Determine how much space you need (e.g. a kernel that is 1 Mbyte or + less and a root filesystem that is 3 Mbytes or less). + +- Find the areas that are currently taking 90% of the space and + concentrate on reducing those areas. + +- Do not create any difficult "hacks" to achieve your goals. + +- Leverage the device-specific options. + +- Work in a separate layer so that you keep changes isolated. For + information on how to create layers, see the + ":ref:`dev-manual/layers:understanding and creating layers`" section. + +Understand What Contributes to Your Image Size +---------------------------------------------- + +It is easiest to have something to start with when creating your own +distribution. You can use the Yocto Project out-of-the-box to create the +``poky-tiny`` distribution. Ultimately, you will want to make changes in +your own distribution that are likely modeled after ``poky-tiny``. + +.. note:: + + To use ``poky-tiny`` in your build, set the :term:`DISTRO` variable in your + ``local.conf`` file to "poky-tiny" as described in the + ":ref:`dev-manual/custom-distribution:creating your own distribution`" + section. + +Understanding some memory concepts will help you reduce the system size. +Memory consists of static, dynamic, and temporary memory. Static memory +is the TEXT (code), DATA (initialized data in the code), and BSS +(uninitialized data) sections. Dynamic memory represents memory that is +allocated at runtime: stacks, hash tables, and so forth. Temporary +memory is recovered after the boot process. This memory consists of +memory used for decompressing the kernel and for the ``__init__`` +functions. + +To help you see where you currently are with kernel and root filesystem +sizes, you can use two tools found in the :term:`Source Directory` +in the +``scripts/tiny/`` directory: + +- ``ksize.py``: Reports component sizes for the kernel build objects. + +- ``dirsize.py``: Reports component sizes for the root filesystem. + +This next tool and command help you organize configuration fragments and +view file dependencies in a human-readable form: + +- ``merge_config.sh``: Helps you manage configuration files and + fragments within the kernel. With this tool, you can merge individual + configuration fragments together. The tool allows you to make + overrides and warns you of any missing configuration options. The + tool is ideal for allowing you to iterate on configurations, create + minimal configurations, and create configuration files for different + machines without having to duplicate your process. + + The ``merge_config.sh`` script is part of the Linux Yocto kernel Git + repositories (i.e. ``linux-yocto-3.14``, ``linux-yocto-3.10``, + ``linux-yocto-3.8``, and so forth) in the ``scripts/kconfig`` + directory. + + For more information on configuration fragments, see the + ":ref:`kernel-dev/common:creating configuration fragments`" + section in the Yocto Project Linux Kernel Development Manual. + +- ``bitbake -u taskexp -g bitbake_target``: Using the BitBake command + with these options brings up a Dependency Explorer from which you can + view file dependencies. Understanding these dependencies allows you + to make informed decisions when cutting out various pieces of the + kernel and root filesystem. + +Trim the Root Filesystem +------------------------ + +The root filesystem is made up of packages for booting, libraries, and +applications. To change things, you can configure how the packaging +happens, which changes the way you build them. You can also modify the +filesystem itself or select a different filesystem. + +First, find out what is hogging your root filesystem by running the +``dirsize.py`` script from your root directory:: + + $ cd root-directory-of-image + $ dirsize.py 100000 > dirsize-100k.log + $ cat dirsize-100k.log + +You can apply a filter to the script to ignore files +under a certain size. The previous example filters out any files below +100 Kbytes. The sizes reported by the tool are uncompressed, and thus +will be smaller by a relatively constant factor in a compressed root +filesystem. When you examine your log file, you can focus on areas of +the root filesystem that take up large amounts of memory. + +You need to be sure that what you eliminate does not cripple the +functionality you need. One way to see how packages relate to each other +is by using the Dependency Explorer UI with the BitBake command:: + + $ cd image-directory + $ bitbake -u taskexp -g image + +Use the interface to +select potential packages you wish to eliminate and see their dependency +relationships. + +When deciding how to reduce the size, get rid of packages that result in +minimal impact on the feature set. For example, you might not need a VGA +display. Or, you might be able to get by with ``devtmpfs`` and ``mdev`` +instead of ``udev``. + +Use your ``local.conf`` file to make changes. For example, to eliminate +``udev`` and ``glib``, set the following in the local configuration +file:: + + VIRTUAL-RUNTIME_dev_manager = "" + +Finally, you should consider exactly the type of root filesystem you +need to meet your needs while also reducing its size. For example, +consider ``cramfs``, ``squashfs``, ``ubifs``, ``ext2``, or an +:term:`Initramfs` using ``initramfs``. Be aware that ``ext3`` requires a 1 +Mbyte journal. If you are okay with running read-only, you do not need +this journal. + +.. note:: + + After each round of elimination, you need to rebuild your system and + then use the tools to see the effects of your reductions. + +Trim the Kernel +--------------- + +The kernel is built by including policies for hardware-independent +aspects. What subsystems do you enable? For what architecture are you +building? Which drivers do you build by default? + +.. note:: + + You can modify the kernel source if you want to help with boot time. + +Run the ``ksize.py`` script from the top-level Linux build directory to +get an idea of what is making up the kernel:: + + $ cd top-level-linux-build-directory + $ ksize.py > ksize.log + $ cat ksize.log + +When you examine the log, you will see how much space is taken up with +the built-in ``.o`` files for drivers, networking, core kernel files, +filesystem, sound, and so forth. The sizes reported by the tool are +uncompressed, and thus will be smaller by a relatively constant factor +in a compressed kernel image. Look to reduce the areas that are large +and taking up around the "90% rule." + +To examine, or drill down, into any particular area, use the ``-d`` +option with the script:: + + $ ksize.py -d > ksize.log + +Using this option +breaks out the individual file information for each area of the kernel +(e.g. drivers, networking, and so forth). + +Use your log file to see what you can eliminate from the kernel based on +features you can let go. For example, if you are not going to need +sound, you do not need any drivers that support sound. + +After figuring out what to eliminate, you need to reconfigure the kernel +to reflect those changes during the next build. You could run +``menuconfig`` and make all your changes at once. However, that makes it +difficult to see the effects of your individual eliminations and also +makes it difficult to replicate the changes for perhaps another target +device. A better method is to start with no configurations using +``allnoconfig``, create configuration fragments for individual changes, +and then manage the fragments into a single configuration file using +``merge_config.sh``. The tool makes it easy for you to iterate using the +configuration change and build cycle. + +Each time you make configuration changes, you need to rebuild the kernel +and check to see what impact your changes had on the overall size. + +Remove Package Management Requirements +-------------------------------------- + +Packaging requirements add size to the image. One way to reduce the size +of the image is to remove all the packaging requirements from the image. +This reduction includes both removing the package manager and its unique +dependencies as well as removing the package management data itself. + +To eliminate all the packaging requirements for an image, be sure that +"package-management" is not part of your +:term:`IMAGE_FEATURES` +statement for the image. When you remove this feature, you are removing +the package manager as well as its dependencies from the root +filesystem. + +Look for Other Ways to Minimize Size +------------------------------------ + +Depending on your particular circumstances, other areas that you can +trim likely exist. The key to finding these areas is through tools and +methods described here combined with experimentation and iteration. Here +are a couple of areas to experiment with: + +- ``glibc``: In general, follow this process: + + #. Remove ``glibc`` features from + :term:`DISTRO_FEATURES` + that you think you do not need. + + #. Build your distribution. + + #. If the build fails due to missing symbols in a package, determine + if you can reconfigure the package to not need those features. For + example, change the configuration to not support wide character + support as is done for ``ncurses``. Or, if support for those + characters is needed, determine what ``glibc`` features provide + the support and restore the configuration. + + 4. Rebuild and repeat the process. + +- ``busybox``: For BusyBox, use a process similar as described for + ``glibc``. A difference is you will need to boot the resulting system + to see if you are able to do everything you expect from the running + system. You need to be sure to integrate configuration fragments into + Busybox because BusyBox handles its own core features and then allows + you to add configuration fragments on top. + +Iterate on the Process +---------------------- + +If you have not reached your goals on system size, you need to iterate +on the process. The process is the same. Use the tools and see just what +is taking up 90% of the root filesystem and the kernel. Decide what you +can eliminate without limiting your device beyond what you need. + +Depending on your system, a good place to look might be Busybox, which +provides a stripped down version of Unix tools in a single, executable +file. You might be able to drop virtual terminal services or perhaps +ipv6. + +Building Images for More than One Machine +========================================= + +A common scenario developers face is creating images for several +different machines that use the same software environment. In this +situation, it is tempting to set the tunings and optimization flags for +each build specifically for the targeted hardware (i.e. "maxing out" the +tunings). Doing so can considerably add to build times and package feed +maintenance collectively for the machines. For example, selecting tunes +that are extremely specific to a CPU core used in a system might enable +some micro optimizations in GCC for that particular system but would +otherwise not gain you much of a performance difference across the other +systems as compared to using a more general tuning across all the builds +(e.g. setting :term:`DEFAULTTUNE` +specifically for each machine's build). Rather than "max out" each +build's tunings, you can take steps that cause the OpenEmbedded build +system to reuse software across the various machines where it makes +sense. + +If build speed and package feed maintenance are considerations, you +should consider the points in this section that can help you optimize +your tunings to best consider build times and package feed maintenance. + +- *Share the :term:`Build Directory`:* If at all possible, share the + :term:`TMPDIR` across builds. The Yocto Project supports switching between + different :term:`MACHINE` values in the same :term:`TMPDIR`. This practice + is well supported and regularly used by developers when building for + multiple machines. When you use the same :term:`TMPDIR` for multiple + machine builds, the OpenEmbedded build system can reuse the existing native + and often cross-recipes for multiple machines. Thus, build time decreases. + + .. note:: + + If :term:`DISTRO` settings change or fundamental configuration settings + such as the filesystem layout, you need to work with a clean :term:`TMPDIR`. + Sharing :term:`TMPDIR` under these circumstances might work but since it is + not guaranteed, you should use a clean :term:`TMPDIR`. + +- *Enable the Appropriate Package Architecture:* By default, the + OpenEmbedded build system enables three levels of package + architectures: "all", "tune" or "package", and "machine". Any given + recipe usually selects one of these package architectures (types) for + its output. Depending for what a given recipe creates packages, + making sure you enable the appropriate package architecture can + directly impact the build time. + + A recipe that just generates scripts can enable "all" architecture + because there are no binaries to build. To specifically enable "all" + architecture, be sure your recipe inherits the + :ref:`ref-classes-allarch` class. + This class is useful for "all" architectures because it configures + many variables so packages can be used across multiple architectures. + + If your recipe needs to generate packages that are machine-specific + or when one of the build or runtime dependencies is already + machine-architecture dependent, which makes your recipe also + machine-architecture dependent, make sure your recipe enables the + "machine" package architecture through the + :term:`MACHINE_ARCH` + variable:: + + PACKAGE_ARCH = "${MACHINE_ARCH}" + + When you do not + specifically enable a package architecture through the + :term:`PACKAGE_ARCH`, The + OpenEmbedded build system defaults to the + :term:`TUNE_PKGARCH` setting:: + + PACKAGE_ARCH = "${TUNE_PKGARCH}" + +- *Choose a Generic Tuning File if Possible:* Some tunes are more + generic and can run on multiple targets (e.g. an ``armv5`` set of + packages could run on ``armv6`` and ``armv7`` processors in most + cases). Similarly, ``i486`` binaries could work on ``i586`` and + higher processors. You should realize, however, that advances on + newer processor versions would not be used. + + If you select the same tune for several different machines, the + OpenEmbedded build system reuses software previously built, thus + speeding up the overall build time. Realize that even though a new + sysroot for each machine is generated, the software is not recompiled + and only one package feed exists. + +- *Manage Granular Level Packaging:* Sometimes there are cases where + injecting another level of package architecture beyond the three + higher levels noted earlier can be useful. For example, consider how + NXP (formerly Freescale) allows for the easy reuse of binary packages + in their layer + :yocto_git:`meta-freescale `. + In this example, the + :yocto_git:`fsl-dynamic-packagearch ` + class shares GPU packages for i.MX53 boards because all boards share + the AMD GPU. The i.MX6-based boards can do the same because all + boards share the Vivante GPU. This class inspects the BitBake + datastore to identify if the package provides or depends on one of + the sub-architecture values. If so, the class sets the + :term:`PACKAGE_ARCH` value + based on the ``MACHINE_SUBARCH`` value. If the package does not + provide or depend on one of the sub-architecture values but it + matches a value in the machine-specific filter, it sets + :term:`MACHINE_ARCH`. This + behavior reduces the number of packages built and saves build time by + reusing binaries. + +- *Use Tools to Debug Issues:* Sometimes you can run into situations + where software is being rebuilt when you think it should not be. For + example, the OpenEmbedded build system might not be using shared + state between machines when you think it should be. These types of + situations are usually due to references to machine-specific + variables such as :term:`MACHINE`, + :term:`SERIAL_CONSOLES`, + :term:`XSERVER`, + :term:`MACHINE_FEATURES`, + and so forth in code that is supposed to only be tune-specific or + when the recipe depends + (:term:`DEPENDS`, + :term:`RDEPENDS`, + :term:`RRECOMMENDS`, + :term:`RSUGGESTS`, and so forth) + on some other recipe that already has + :term:`PACKAGE_ARCH` defined + as "${MACHINE_ARCH}". + + .. note:: + + Patches to fix any issues identified are most welcome as these + issues occasionally do occur. + + For such cases, you can use some tools to help you sort out the + situation: + + - ``state-diff-machines.sh``*:* You can find this tool in the + ``scripts`` directory of the Source Repositories. See the comments + in the script for information on how to use the tool. + + - *BitBake's "-S printdiff" Option:* Using this option causes + BitBake to try to establish the closest signature match it can + (e.g. in the shared state cache) and then run ``bitbake-diffsigs`` + over the matches to determine the stamps and delta where these two + stamp trees diverge. + +Building Software from an External Source +========================================= + +By default, the OpenEmbedded build system uses the :term:`Build Directory` +when building source code. The build process involves fetching the source +files, unpacking them, and then patching them if necessary before the build +takes place. + +There are situations where you might want to build software from source +files that are external to and thus outside of the OpenEmbedded build +system. For example, suppose you have a project that includes a new BSP +with a heavily customized kernel. And, you want to minimize exposing the +build system to the development team so that they can focus on their +project and maintain everyone's workflow as much as possible. In this +case, you want a kernel source directory on the development machine +where the development occurs. You want the recipe's +:term:`SRC_URI` variable to point to +the external directory and use it as is, not copy it. + +To build from software that comes from an external source, all you need to do +is inherit the :ref:`ref-classes-externalsrc` class and then set +the :term:`EXTERNALSRC` variable to point to your external source code. Here +are the statements to put in your ``local.conf`` file:: + + INHERIT += "externalsrc" + EXTERNALSRC:pn-myrecipe = "path-to-your-source-tree" + +This next example shows how to accomplish the same thing by setting +:term:`EXTERNALSRC` in the recipe itself or in the recipe's append file:: + + EXTERNALSRC = "path" + EXTERNALSRC_BUILD = "path" + +.. note:: + + In order for these settings to take effect, you must globally or + locally inherit the :ref:`ref-classes-externalsrc` class. + +By default, :ref:`ref-classes-externalsrc` builds the source code in a +directory separate from the external source directory as specified by +:term:`EXTERNALSRC`. If you need +to have the source built in the same directory in which it resides, or +some other nominated directory, you can set +:term:`EXTERNALSRC_BUILD` +to point to that directory:: + + EXTERNALSRC_BUILD:pn-myrecipe = "path-to-your-source-tree" + +Replicating a Build Offline +=========================== + +It can be useful to take a "snapshot" of upstream sources used in a +build and then use that "snapshot" later to replicate the build offline. +To do so, you need to first prepare and populate your downloads +directory your "snapshot" of files. Once your downloads directory is +ready, you can use it at any time and from any machine to replicate your +build. + +Follow these steps to populate your Downloads directory: + +#. *Create a Clean Downloads Directory:* Start with an empty downloads + directory (:term:`DL_DIR`). You + start with an empty downloads directory by either removing the files + in the existing directory or by setting :term:`DL_DIR` to point to either + an empty location or one that does not yet exist. + +#. *Generate Tarballs of the Source Git Repositories:* Edit your + ``local.conf`` configuration file as follows:: + + DL_DIR = "/home/your-download-dir/" + BB_GENERATE_MIRROR_TARBALLS = "1" + + During + the fetch process in the next step, BitBake gathers the source files + and creates tarballs in the directory pointed to by :term:`DL_DIR`. See + the + :term:`BB_GENERATE_MIRROR_TARBALLS` + variable for more information. + +#. *Populate Your Downloads Directory Without Building:* Use BitBake to + fetch your sources but inhibit the build:: + + $ bitbake target --runonly=fetch + + The downloads directory (i.e. ``${DL_DIR}``) now has + a "snapshot" of the source files in the form of tarballs, which can + be used for the build. + +#. *Optionally Remove Any Git or other SCM Subdirectories From the + Downloads Directory:* If you want, you can clean up your downloads + directory by removing any Git or other Source Control Management + (SCM) subdirectories such as ``${DL_DIR}/git2/*``. The tarballs + already contain these subdirectories. + +Once your downloads directory has everything it needs regarding source +files, you can create your "own-mirror" and build your target. +Understand that you can use the files to build the target offline from +any machine and at any time. + +Follow these steps to build your target using the files in the downloads +directory: + +#. *Using Local Files Only:* Inside your ``local.conf`` file, add the + :term:`SOURCE_MIRROR_URL` variable, inherit the + :ref:`ref-classes-own-mirrors` class, and use the + :term:`BB_NO_NETWORK` variable to your ``local.conf``:: + + SOURCE_MIRROR_URL ?= "file:///home/your-download-dir/" + INHERIT += "own-mirrors" + BB_NO_NETWORK = "1" + + The :term:`SOURCE_MIRROR_URL` and :ref:`ref-classes-own-mirrors` + class set up the system to use the downloads directory as your "own + mirror". Using the :term:`BB_NO_NETWORK` variable makes sure that + BitBake's fetching process in step 3 stays local, which means files + from your "own-mirror" are used. + +#. *Start With a Clean Build:* You can start with a clean build by + removing the ``${``\ :term:`TMPDIR`\ ``}`` directory or using a new + :term:`Build Directory`. + +#. *Build Your Target:* Use BitBake to build your target:: + + $ bitbake target + + The build completes using the known local "snapshot" of source + files from your mirror. The resulting tarballs for your "snapshot" of + source files are in the downloads directory. + + .. note:: + + The offline build does not work if recipes attempt to find the + latest version of software by setting + :term:`SRCREV` to + ``${``\ :term:`AUTOREV`\ ``}``:: + + SRCREV = "${AUTOREV}" + + When a recipe sets :term:`SRCREV` to + ``${``\ :term:`AUTOREV`\ ``}``, the build system accesses the network in an + attempt to determine the latest version of software from the SCM. + Typically, recipes that use :term:`AUTOREV` are custom or modified + recipes. Recipes that reside in public repositories usually do not + use :term:`AUTOREV`. + + If you do have recipes that use :term:`AUTOREV`, you can take steps to + still use the recipes in an offline build. Do the following: + + #. Use a configuration generated by enabling :ref:`build + history `. + + #. Use the ``buildhistory-collect-srcrevs`` command to collect the + stored :term:`SRCREV` values from the build's history. For more + information on collecting these values, see the + ":ref:`dev-manual/build-quality:build history package information`" + section. + + #. Once you have the correct source revisions, you can modify + those recipes to set :term:`SRCREV` to specific versions of the + software. + diff --git a/documentation/dev-manual/common-tasks.rst b/documentation/dev-manual/common-tasks.rst deleted file mode 100644 index a2404e5f4e..0000000000 --- a/documentation/dev-manual/common-tasks.rst +++ /dev/null @@ -1,11414 +0,0 @@ -.. SPDX-License-Identifier: CC-BY-SA-2.0-UK - -************ -Common Tasks -************ - -This chapter describes fundamental procedures such as creating layers, -adding new software packages, extending or customizing images, porting -work to new hardware (adding a new machine), and so forth. You will find -that the procedures documented here occur often in the development cycle -using the Yocto Project. - -Understanding and Creating Layers -================================= - -The OpenEmbedded build system supports organizing -:term:`Metadata` into multiple layers. -Layers allow you to isolate different types of customizations from each -other. For introductory information on the Yocto Project Layer Model, -see the -":ref:`overview-manual/yp-intro:the yocto project layer model`" -section in the Yocto Project Overview and Concepts Manual. - -Creating Your Own Layer ------------------------ - -.. note:: - - It is very easy to create your own layers to use with the OpenEmbedded - build system, as the Yocto Project ships with tools that speed up creating - layers. This section describes the steps you perform by hand to create - layers so that you can better understand them. For information about the - layer-creation tools, see the - ":ref:`bsp-guide/bsp:creating a new bsp layer using the \`\`bitbake-layers\`\` script`" - section in the Yocto Project Board Support Package (BSP) Developer's - Guide and the ":ref:`dev-manual/common-tasks:creating a general layer using the \`\`bitbake-layers\`\` script`" - section further down in this manual. - -Follow these general steps to create your layer without using tools: - -1. *Check Existing Layers:* Before creating a new layer, you should be - sure someone has not already created a layer containing the Metadata - you need. You can see the :oe_layerindex:`OpenEmbedded Metadata Index <>` - for a list of layers from the OpenEmbedded community that can be used in - the Yocto Project. You could find a layer that is identical or close - to what you need. - -2. *Create a Directory:* Create the directory for your layer. When you - create the layer, be sure to create the directory in an area not - associated with the Yocto Project :term:`Source Directory` - (e.g. the cloned ``poky`` repository). - - While not strictly required, prepend the name of the directory with - the string "meta-". For example:: - - meta-mylayer - meta-GUI_xyz - meta-mymachine - - With rare exceptions, a layer's name follows this form:: - - meta-root_name - - Following this layer naming convention can save - you trouble later when tools, components, or variables "assume" your - layer name begins with "meta-". A notable example is in configuration - files as shown in the following step where layer names without the - "meta-" string are appended to several variables used in the - configuration. - -3. *Create a Layer Configuration File:* Inside your new layer folder, - you need to create a ``conf/layer.conf`` file. It is easiest to take - an existing layer configuration file and copy that to your layer's - ``conf`` directory and then modify the file as needed. - - The ``meta-yocto-bsp/conf/layer.conf`` file in the Yocto Project - :yocto_git:`Source Repositories ` - demonstrates the required syntax. For your layer, you need to replace - "yoctobsp" with a unique identifier for your layer (e.g. "machinexyz" - for a layer named "meta-machinexyz"):: - - # We have a conf and classes directory, add to BBPATH - BBPATH .= ":${LAYERDIR}" - - # We have recipes-* directories, add to BBFILES - BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \ - ${LAYERDIR}/recipes-*/*/*.bbappend" - - BBFILE_COLLECTIONS += "yoctobsp" - BBFILE_PATTERN_yoctobsp = "^${LAYERDIR}/" - BBFILE_PRIORITY_yoctobsp = "5" - LAYERVERSION_yoctobsp = "4" - LAYERSERIES_COMPAT_yoctobsp = "dunfell" - - Following is an explanation of the layer configuration file: - - - :term:`BBPATH`: Adds the layer's - root directory to BitBake's search path. Through the use of the - :term:`BBPATH` variable, BitBake locates class files (``.bbclass``), - configuration files, and files that are included with ``include`` - and ``require`` statements. For these cases, BitBake uses the - first file that matches the name found in :term:`BBPATH`. This is - similar to the way the ``PATH`` variable is used for binaries. It - is recommended, therefore, that you use unique class and - configuration filenames in your custom layer. - - - :term:`BBFILES`: Defines the - location for all recipes in the layer. - - - :term:`BBFILE_COLLECTIONS`: - Establishes the current layer through a unique identifier that is - used throughout the OpenEmbedded build system to refer to the - layer. In this example, the identifier "yoctobsp" is the - representation for the container layer named "meta-yocto-bsp". - - - :term:`BBFILE_PATTERN`: - Expands immediately during parsing to provide the directory of the - layer. - - - :term:`BBFILE_PRIORITY`: - Establishes a priority to use for recipes in the layer when the - OpenEmbedded build finds recipes of the same name in different - layers. - - - :term:`LAYERVERSION`: - Establishes a version number for the layer. You can use this - version number to specify this exact version of the layer as a - dependency when using the - :term:`LAYERDEPENDS` - variable. - - - :term:`LAYERDEPENDS`: - Lists all layers on which this layer depends (if any). - - - :term:`LAYERSERIES_COMPAT`: - Lists the :yocto_wiki:`Yocto Project ` - releases for which the current version is compatible. This - variable is a good way to indicate if your particular layer is - current. - -4. *Add Content:* Depending on the type of layer, add the content. If - the layer adds support for a machine, add the machine configuration - in a ``conf/machine/`` file within the layer. If the layer adds - distro policy, add the distro configuration in a ``conf/distro/`` - file within the layer. If the layer introduces new recipes, put the - recipes you need in ``recipes-*`` subdirectories within the layer. - - .. note:: - - For an explanation of layer hierarchy that is compliant with the - Yocto Project, see the ":ref:`bsp-guide/bsp:example filesystem layout`" - section in the Yocto Project Board Support Package (BSP) Developer's Guide. - -5. *Optionally Test for Compatibility:* If you want permission to use - the Yocto Project Compatibility logo with your layer or application - that uses your layer, perform the steps to apply for compatibility. - See the - ":ref:`dev-manual/common-tasks:making sure your layer is compatible with yocto project`" - section for more information. - -Following Best Practices When Creating Layers ---------------------------------------------- - -To create layers that are easier to maintain and that will not impact -builds for other machines, you should consider the information in the -following list: - -- *Avoid "Overlaying" Entire Recipes from Other Layers in Your - Configuration:* In other words, do not copy an entire recipe into - your layer and then modify it. Rather, use an append file - (``.bbappend``) to override only those parts of the original recipe - you need to modify. - -- *Avoid Duplicating Include Files:* Use append files (``.bbappend``) - for each recipe that uses an include file. Or, if you are introducing - a new recipe that requires the included file, use the path relative - to the original layer directory to refer to the file. For example, - use ``require recipes-core/``\ `package`\ ``/``\ `file`\ ``.inc`` instead - of ``require`` `file`\ ``.inc``. If you're finding you have to overlay - the include file, it could indicate a deficiency in the include file - in the layer to which it originally belongs. If this is the case, you - should try to address that deficiency instead of overlaying the - include file. For example, you could address this by getting the - maintainer of the include file to add a variable or variables to make - it easy to override the parts needing to be overridden. - -- *Structure Your Layers:* Proper use of overrides within append files - and placement of machine-specific files within your layer can ensure - that a build is not using the wrong Metadata and negatively impacting - a build for a different machine. Following are some examples: - - - *Modify Variables to Support a Different Machine:* Suppose you - have a layer named ``meta-one`` that adds support for building - machine "one". To do so, you use an append file named - ``base-files.bbappend`` and create a dependency on "foo" by - altering the :term:`DEPENDS` - variable:: - - DEPENDS = "foo" - - The dependency is created during any - build that includes the layer ``meta-one``. However, you might not - want this dependency for all machines. For example, suppose you - are building for machine "two" but your ``bblayers.conf`` file has - the ``meta-one`` layer included. During the build, the - ``base-files`` for machine "two" will also have the dependency on - ``foo``. - - To make sure your changes apply only when building machine "one", - use a machine override with the :term:`DEPENDS` statement:: - - DEPENDS:one = "foo" - - You should follow the same strategy when using ``:append`` - and ``:prepend`` operations:: - - DEPENDS:append:one = " foo" - DEPENDS:prepend:one = "foo " - - As an actual example, here's a - snippet from the generic kernel include file ``linux-yocto.inc``, - wherein the kernel compile and link options are adjusted in the - case of a subset of the supported architectures:: - - DEPENDS:append:aarch64 = " libgcc" - KERNEL_CC:append:aarch64 = " ${TOOLCHAIN_OPTIONS}" - KERNEL_LD:append:aarch64 = " ${TOOLCHAIN_OPTIONS}" - - DEPENDS:append:nios2 = " libgcc" - KERNEL_CC:append:nios2 = " ${TOOLCHAIN_OPTIONS}" - KERNEL_LD:append:nios2 = " ${TOOLCHAIN_OPTIONS}" - - DEPENDS:append:arc = " libgcc" - KERNEL_CC:append:arc = " ${TOOLCHAIN_OPTIONS}" - KERNEL_LD:append:arc = " ${TOOLCHAIN_OPTIONS}" - - KERNEL_FEATURES:append:qemuall=" features/debug/printk.scc" - - - *Place Machine-Specific Files in Machine-Specific Locations:* When - you have a base recipe, such as ``base-files.bb``, that contains a - :term:`SRC_URI` statement to a - file, you can use an append file to cause the build to use your - own version of the file. For example, an append file in your layer - at ``meta-one/recipes-core/base-files/base-files.bbappend`` could - extend :term:`FILESPATH` using :term:`FILESEXTRAPATHS` as follows:: - - FILESEXTRAPATHS:prepend := "${THISDIR}/${BPN}:" - - The build for machine "one" will pick up your machine-specific file as - long as you have the file in - ``meta-one/recipes-core/base-files/base-files/``. However, if you - are building for a different machine and the ``bblayers.conf`` - file includes the ``meta-one`` layer and the location of your - machine-specific file is the first location where that file is - found according to :term:`FILESPATH`, builds for all machines will - also use that machine-specific file. - - You can make sure that a machine-specific file is used for a - particular machine by putting the file in a subdirectory specific - to the machine. For example, rather than placing the file in - ``meta-one/recipes-core/base-files/base-files/`` as shown above, - put it in ``meta-one/recipes-core/base-files/base-files/one/``. - Not only does this make sure the file is used only when building - for machine "one", but the build process locates the file more - quickly. - - In summary, you need to place all files referenced from - :term:`SRC_URI` in a machine-specific subdirectory within the layer in - order to restrict those files to machine-specific builds. - -- *Perform Steps to Apply for Yocto Project Compatibility:* If you want - permission to use the Yocto Project Compatibility logo with your - layer or application that uses your layer, perform the steps to apply - for compatibility. See the - ":ref:`dev-manual/common-tasks:making sure your layer is compatible with yocto project`" - section for more information. - -- *Follow the Layer Naming Convention:* Store custom layers in a Git - repository that use the ``meta-layer_name`` format. - -- *Group Your Layers Locally:* Clone your repository alongside other - cloned ``meta`` directories from the :term:`Source Directory`. - -Making Sure Your Layer is Compatible With Yocto Project -------------------------------------------------------- - -When you create a layer used with the Yocto Project, it is advantageous -to make sure that the layer interacts well with existing Yocto Project -layers (i.e. the layer is compatible with the Yocto Project). Ensuring -compatibility makes the layer easy to be consumed by others in the Yocto -Project community and could allow you permission to use the Yocto -Project Compatible Logo. - -.. note:: - - Only Yocto Project member organizations are permitted to use the - Yocto Project Compatible Logo. The logo is not available for general - use. For information on how to become a Yocto Project member - organization, see the :yocto_home:`Yocto Project Website <>`. - -The Yocto Project Compatibility Program consists of a layer application -process that requests permission to use the Yocto Project Compatibility -Logo for your layer and application. The process consists of two parts: - -1. Successfully passing a script (``yocto-check-layer``) that when run - against your layer, tests it against constraints based on experiences - of how layers have worked in the real world and where pitfalls have - been found. Getting a "PASS" result from the script is required for - successful compatibility registration. - -2. Completion of an application acceptance form, which you can find at - :yocto_home:`/webform/yocto-project-compatible-registration`. - -To be granted permission to use the logo, you need to satisfy the -following: - -- Be able to check the box indicating that you got a "PASS" when - running the script against your layer. - -- Answer "Yes" to the questions on the form or have an acceptable - explanation for any questions answered "No". - -- Be a Yocto Project Member Organization. - -The remainder of this section presents information on the registration -form and on the ``yocto-check-layer`` script. - -Yocto Project Compatible Program Application -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Use the form to apply for your layer's approval. Upon successful -application, you can use the Yocto Project Compatibility Logo with your -layer and the application that uses your layer. - -To access the form, use this link: -:yocto_home:`/webform/yocto-project-compatible-registration`. -Follow the instructions on the form to complete your application. - -The application consists of the following sections: - -- *Contact Information:* Provide your contact information as the fields - require. Along with your information, provide the released versions - of the Yocto Project for which your layer is compatible. - -- *Acceptance Criteria:* Provide "Yes" or "No" answers for each of the - items in the checklist. There is space at the bottom of the form for - any explanations for items for which you answered "No". - -- *Recommendations:* Provide answers for the questions regarding Linux - kernel use and build success. - -``yocto-check-layer`` Script -~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The ``yocto-check-layer`` script provides you a way to assess how -compatible your layer is with the Yocto Project. You should run this -script prior to using the form to apply for compatibility as described -in the previous section. You need to achieve a "PASS" result in order to -have your application form successfully processed. - -The script divides tests into three areas: COMMON, BSP, and DISTRO. For -example, given a distribution layer (DISTRO), the layer must pass both -the COMMON and DISTRO related tests. Furthermore, if your layer is a BSP -layer, the layer must pass the COMMON and BSP set of tests. - -To execute the script, enter the following commands from your build -directory:: - - $ source oe-init-build-env - $ yocto-check-layer your_layer_directory - -Be sure to provide the actual directory for your -layer as part of the command. - -Entering the command causes the script to determine the type of layer -and then to execute a set of specific tests against the layer. The -following list overviews the test: - -- ``common.test_readme``: Tests if a ``README`` file exists in the - layer and the file is not empty. - -- ``common.test_parse``: Tests to make sure that BitBake can parse the - files without error (i.e. ``bitbake -p``). - -- ``common.test_show_environment``: Tests that the global or per-recipe - environment is in order without errors (i.e. ``bitbake -e``). - -- ``common.test_world``: Verifies that ``bitbake world`` works. - -- ``common.test_signatures``: Tests to be sure that BSP and DISTRO - layers do not come with recipes that change signatures. - -- ``common.test_layerseries_compat``: Verifies layer compatibility is - set properly. - -- ``bsp.test_bsp_defines_machines``: Tests if a BSP layer has machine - configurations. - -- ``bsp.test_bsp_no_set_machine``: Tests to ensure a BSP layer does not - set the machine when the layer is added. - -- ``bsp.test_machine_world``: Verifies that ``bitbake world`` works - regardless of which machine is selected. - -- ``bsp.test_machine_signatures``: Verifies that building for a - particular machine affects only the signature of tasks specific to - that machine. - -- ``distro.test_distro_defines_distros``: Tests if a DISTRO layer has - distro configurations. - -- ``distro.test_distro_no_set_distros``: Tests to ensure a DISTRO layer - does not set the distribution when the layer is added. - -Enabling Your Layer -------------------- - -Before the OpenEmbedded build system can use your new layer, you need to -enable it. To enable your layer, simply add your layer's path to the -:term:`BBLAYERS` variable in your ``conf/bblayers.conf`` file, which is -found in the :term:`Build Directory`. -The following example shows how to enable your new -``meta-mylayer`` layer (note how your new layer exists outside of -the official ``poky`` repository which you would have checked out earlier):: - - # POKY_BBLAYERS_CONF_VERSION is increased each time build/conf/bblayers.conf - # changes incompatibly - POKY_BBLAYERS_CONF_VERSION = "2" - BBPATH = "${TOPDIR}" - BBFILES ?= "" - BBLAYERS ?= " \ - /home/user/poky/meta \ - /home/user/poky/meta-poky \ - /home/user/poky/meta-yocto-bsp \ - /home/user/mystuff/meta-mylayer \ - " - -BitBake parses each ``conf/layer.conf`` file from the top down as -specified in the :term:`BBLAYERS` variable within the ``conf/bblayers.conf`` -file. During the processing of each ``conf/layer.conf`` file, BitBake -adds the recipes, classes and configurations contained within the -particular layer to the source directory. - -Appending Other Layers Metadata With Your Layer ------------------------------------------------ - -A recipe that appends Metadata to another recipe is called a BitBake -append file. A BitBake append file uses the ``.bbappend`` file type -suffix, while the corresponding recipe to which Metadata is being -appended uses the ``.bb`` file type suffix. - -You can use a ``.bbappend`` file in your layer to make additions or -changes to the content of another layer's recipe without having to copy -the other layer's recipe into your layer. Your ``.bbappend`` file -resides in your layer, while the main ``.bb`` recipe file to which you -are appending Metadata resides in a different layer. - -Being able to append information to an existing recipe not only avoids -duplication, but also automatically applies recipe changes from a -different layer into your layer. If you were copying recipes, you would -have to manually merge changes as they occur. - -When you create an append file, you must use the same root name as the -corresponding recipe file. For example, the append file -``someapp_3.1.bbappend`` must apply to ``someapp_3.1.bb``. This -means the original recipe and append filenames are version -number-specific. If the corresponding recipe is renamed to update to a -newer version, you must also rename and possibly update the -corresponding ``.bbappend`` as well. During the build process, BitBake -displays an error on starting if it detects a ``.bbappend`` file that -does not have a corresponding recipe with a matching name. See the -:term:`BB_DANGLINGAPPENDS_WARNONLY` -variable for information on how to handle this error. - -Overlaying a File Using Your Layer -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -As an example, consider the main formfactor recipe and a corresponding -formfactor append file both from the :term:`Source Directory`. -Here is the main -formfactor recipe, which is named ``formfactor_0.0.bb`` and located in -the "meta" layer at ``meta/recipes-bsp/formfactor``:: - - SUMMARY = "Device formfactor information" - DESCRIPTION = "A formfactor configuration file provides information about the \ - target hardware for which the image is being built and information that the \ - build system cannot obtain from other sources such as the kernel." - SECTION = "base" - LICENSE = "MIT" - LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420" - PR = "r45" - - SRC_URI = "file://config file://machconfig" - S = "${WORKDIR}" - - PACKAGE_ARCH = "${MACHINE_ARCH}" - INHIBIT_DEFAULT_DEPS = "1" - - do_install() { - # Install file only if it has contents - install -d ${D}${sysconfdir}/formfactor/ - install -m 0644 ${S}/config ${D}${sysconfdir}/formfactor/ - if [ -s "${S}/machconfig" ]; then - install -m 0644 ${S}/machconfig ${D}${sysconfdir}/formfactor/ - fi - } - -In the main recipe, note the :term:`SRC_URI` -variable, which tells the OpenEmbedded build system where to find files -during the build. - -Following is the append file, which is named ``formfactor_0.0.bbappend`` -and is from the Raspberry Pi BSP Layer named ``meta-raspberrypi``. The -file is in the layer at ``recipes-bsp/formfactor``:: - - FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:" - -By default, the build system uses the -:term:`FILESPATH` variable to -locate files. This append file extends the locations by setting the -:term:`FILESEXTRAPATHS` -variable. Setting this variable in the ``.bbappend`` file is the most -reliable and recommended method for adding directories to the search -path used by the build system to find files. - -The statement in this example extends the directories to include -``${``\ :term:`THISDIR`\ ``}/${``\ :term:`PN`\ ``}``, -which resolves to a directory named ``formfactor`` in the same directory -in which the append file resides (i.e. -``meta-raspberrypi/recipes-bsp/formfactor``. This implies that you must -have the supporting directory structure set up that will contain any -files or patches you will be including from the layer. - -Using the immediate expansion assignment operator ``:=`` is important -because of the reference to :term:`THISDIR`. The trailing colon character is -important as it ensures that items in the list remain colon-separated. - -.. note:: - - BitBake automatically defines the :term:`THISDIR` variable. You should - never set this variable yourself. Using ":prepend" as part of the - :term:`FILESEXTRAPATHS` ensures your path will be searched prior to other - paths in the final list. - - Also, not all append files add extra files. Many append files simply - allow to add build options (e.g. ``systemd``). For these cases, your - append file would not even use the :term:`FILESEXTRAPATHS` statement. - -The end result of this ``.bbappend`` file is that on a Raspberry Pi, where -``rpi`` will exist in the list of :term:`OVERRIDES`, the file -``meta-raspberrypi/recipes-bsp/formfactor/formfactor/rpi/machconfig`` will be -used during :ref:`ref-tasks-fetch` and the test for a non-zero file size in -:ref:`ref-tasks-install` will return true, and the file will be installed. - -Installing Additional Files Using Your Layer -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -As another example, consider the main ``xserver-xf86-config`` recipe and a -corresponding ``xserver-xf86-config`` append file both from the :term:`Source -Directory`. Here is the main ``xserver-xf86-config`` recipe, which is named -``xserver-xf86-config_0.1.bb`` and located in the "meta" layer at -``meta/recipes-graphics/xorg-xserver``:: - - SUMMARY = "X.Org X server configuration file" - HOMEPAGE = "http://www.x.org" - SECTION = "x11/base" - LICENSE = "MIT" - LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420" - PR = "r33" - - SRC_URI = "file://xorg.conf" - - S = "${WORKDIR}" - - CONFFILES:${PN} = "${sysconfdir}/X11/xorg.conf" - - PACKAGE_ARCH = "${MACHINE_ARCH}" - ALLOW_EMPTY:${PN} = "1" - - do_install () { - if test -s ${WORKDIR}/xorg.conf; then - install -d ${D}/${sysconfdir}/X11 - install -m 0644 ${WORKDIR}/xorg.conf ${D}/${sysconfdir}/X11/ - fi - } - -Following is the append file, which is named ``xserver-xf86-config_%.bbappend`` -and is from the Raspberry Pi BSP Layer named ``meta-raspberrypi``. The -file is in the layer at ``recipes-graphics/xorg-xserver``:: - - FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:" - - SRC_URI:append:rpi = " \ - file://xorg.conf.d/98-pitft.conf \ - file://xorg.conf.d/99-calibration.conf \ - " - do_install:append:rpi () { - PITFT="${@bb.utils.contains("MACHINE_FEATURES", "pitft", "1", "0", d)}" - if [ "${PITFT}" = "1" ]; then - install -d ${D}/${sysconfdir}/X11/xorg.conf.d/ - install -m 0644 ${WORKDIR}/xorg.conf.d/98-pitft.conf ${D}/${sysconfdir}/X11/xorg.conf.d/ - install -m 0644 ${WORKDIR}/xorg.conf.d/99-calibration.conf ${D}/${sysconfdir}/X11/xorg.conf.d/ - fi - } - - FILES:${PN}:append:rpi = " ${sysconfdir}/X11/xorg.conf.d/*" - -Building off of the previous example, we once again are setting the -:term:`FILESEXTRAPATHS` variable. In this case we are also using -:term:`SRC_URI` to list additional source files to use when ``rpi`` is found in -the list of :term:`OVERRIDES`. The :ref:`ref-tasks-install` task will then perform a -check for an additional :term:`MACHINE_FEATURES` that if set will cause these -additional files to be installed. These additional files are listed in -:term:`FILES` so that they will be packaged. - -Prioritizing Your Layer ------------------------ - -Each layer is assigned a priority value. Priority values control which -layer takes precedence if there are recipe files with the same name in -multiple layers. For these cases, the recipe file from the layer with a -higher priority number takes precedence. Priority values also affect the -order in which multiple ``.bbappend`` files for the same recipe are -applied. You can either specify the priority manually, or allow the -build system to calculate it based on the layer's dependencies. - -To specify the layer's priority manually, use the -:term:`BBFILE_PRIORITY` -variable and append the layer's root name:: - - BBFILE_PRIORITY_mylayer = "1" - -.. note:: - - It is possible for a recipe with a lower version number - :term:`PV` in a layer that has a higher - priority to take precedence. - - Also, the layer priority does not currently affect the precedence - order of ``.conf`` or ``.bbclass`` files. Future versions of BitBake - might address this. - -Managing Layers ---------------- - -You can use the BitBake layer management tool ``bitbake-layers`` to -provide a view into the structure of recipes across a multi-layer -project. Being able to generate output that reports on configured layers -with their paths and priorities and on ``.bbappend`` files and their -applicable recipes can help to reveal potential problems. - -For help on the BitBake layer management tool, use the following -command:: - - $ bitbake-layers --help - NOTE: Starting bitbake server... - usage: bitbake-layers [-d] [-q] [-F] [--color COLOR] [-h] ... - - BitBake layers utility - - optional arguments: - -d, --debug Enable debug output - -q, --quiet Print only errors - -F, --force Force add without recipe parse verification - --color COLOR Colorize output (where COLOR is auto, always, never) - -h, --help show this help message and exit - - subcommands: - - layerindex-fetch Fetches a layer from a layer index along with its - dependent layers, and adds them to conf/bblayers.conf. - layerindex-show-depends - Find layer dependencies from layer index. - add-layer Add one or more layers to bblayers.conf. - remove-layer Remove one or more layers from bblayers.conf. - flatten flatten layer configuration into a separate output - directory. - show-layers show current configured layers. - show-overlayed list overlayed recipes (where the same recipe exists - in another layer) - show-recipes list available recipes, showing the layer they are - provided by - show-appends list bbappend files and recipe files they apply to - show-cross-depends Show dependencies between recipes that cross layer - boundaries. - create-layer Create a basic layer - - Use bitbake-layers --help to get help on a specific command - -The following list describes the available commands: - -- ``help:`` Displays general help or help on a specified command. - -- ``show-layers:`` Shows the current configured layers. - -- ``show-overlayed:`` Lists overlayed recipes. A recipe is overlayed - when a recipe with the same name exists in another layer that has a - higher layer priority. - -- ``show-recipes:`` Lists available recipes and the layers that - provide them. - -- ``show-appends:`` Lists ``.bbappend`` files and the recipe files to - which they apply. - -- ``show-cross-depends:`` Lists dependency relationships between - recipes that cross layer boundaries. - -- ``add-layer:`` Adds a layer to ``bblayers.conf``. - -- ``remove-layer:`` Removes a layer from ``bblayers.conf`` - -- ``flatten:`` Flattens the layer configuration into a separate - output directory. Flattening your layer configuration builds a - "flattened" directory that contains the contents of all layers, with - any overlayed recipes removed and any ``.bbappend`` files appended to - the corresponding recipes. You might have to perform some manual - cleanup of the flattened layer as follows: - - - Non-recipe files (such as patches) are overwritten. The flatten - command shows a warning for these files. - - - Anything beyond the normal layer setup has been added to the - ``layer.conf`` file. Only the lowest priority layer's - ``layer.conf`` is used. - - - Overridden and appended items from ``.bbappend`` files need to be - cleaned up. The contents of each ``.bbappend`` end up in the - flattened recipe. However, if there are appended or changed - variable values, you need to tidy these up yourself. Consider the - following example. Here, the ``bitbake-layers`` command adds the - line ``#### bbappended ...`` so that you know where the following - lines originate:: - - ... - DESCRIPTION = "A useful utility" - ... - EXTRA_OECONF = "--enable-something" - ... - - #### bbappended from meta-anotherlayer #### - - DESCRIPTION = "Customized utility" - EXTRA_OECONF += "--enable-somethingelse" - - - Ideally, you would tidy up these utilities as follows:: - - ... - DESCRIPTION = "Customized utility" - ... - EXTRA_OECONF = "--enable-something --enable-somethingelse" - ... - -- ``layerindex-fetch``: Fetches a layer from a layer index, along - with its dependent layers, and adds the layers to the - ``conf/bblayers.conf`` file. - -- ``layerindex-show-depends``: Finds layer dependencies from the - layer index. - -- ``create-layer``: Creates a basic layer. - -Creating a General Layer Using the ``bitbake-layers`` Script ------------------------------------------------------------- - -The ``bitbake-layers`` script with the ``create-layer`` subcommand -simplifies creating a new general layer. - -.. note:: - - - For information on BSP layers, see the ":ref:`bsp-guide/bsp:bsp layers`" - section in the Yocto - Project Board Specific (BSP) Developer's Guide. - - - In order to use a layer with the OpenEmbedded build system, you - need to add the layer to your ``bblayers.conf`` configuration - file. See the ":ref:`dev-manual/common-tasks:adding a layer using the \`\`bitbake-layers\`\` script`" - section for more information. - -The default mode of the script's operation with this subcommand is to -create a layer with the following: - -- A layer priority of 6. - -- A ``conf`` subdirectory that contains a ``layer.conf`` file. - -- A ``recipes-example`` subdirectory that contains a further - subdirectory named ``example``, which contains an ``example.bb`` - recipe file. - -- A ``COPYING.MIT``, which is the license statement for the layer. The - script assumes you want to use the MIT license, which is typical for - most layers, for the contents of the layer itself. - -- A ``README`` file, which is a file describing the contents of your - new layer. - -In its simplest form, you can use the following command form to create a -layer. The command creates a layer whose name corresponds to -"your_layer_name" in the current directory:: - - $ bitbake-layers create-layer your_layer_name - -As an example, the following command creates a layer named ``meta-scottrif`` -in your home directory:: - - $ cd /usr/home - $ bitbake-layers create-layer meta-scottrif - NOTE: Starting bitbake server... - Add your new layer with 'bitbake-layers add-layer meta-scottrif' - -If you want to set the priority of the layer to other than the default -value of "6", you can either use the ``--priority`` option or you -can edit the -:term:`BBFILE_PRIORITY` value -in the ``conf/layer.conf`` after the script creates it. Furthermore, if -you want to give the example recipe file some name other than the -default, you can use the ``--example-recipe-name`` option. - -The easiest way to see how the ``bitbake-layers create-layer`` command -works is to experiment with the script. You can also read the usage -information by entering the following:: - - $ bitbake-layers create-layer --help - NOTE: Starting bitbake server... - usage: bitbake-layers create-layer [-h] [--priority PRIORITY] - [--example-recipe-name EXAMPLERECIPE] - layerdir - - Create a basic layer - - positional arguments: - layerdir Layer directory to create - - optional arguments: - -h, --help show this help message and exit - --priority PRIORITY, -p PRIORITY - Layer directory to create - --example-recipe-name EXAMPLERECIPE, -e EXAMPLERECIPE - Filename of the example recipe - -Adding a Layer Using the ``bitbake-layers`` Script --------------------------------------------------- - -Once you create your general layer, you must add it to your -``bblayers.conf`` file. Adding the layer to this configuration file -makes the OpenEmbedded build system aware of your layer so that it can -search it for metadata. - -Add your layer by using the ``bitbake-layers add-layer`` command:: - - $ bitbake-layers add-layer your_layer_name - -Here is an example that adds a -layer named ``meta-scottrif`` to the configuration file. Following the -command that adds the layer is another ``bitbake-layers`` command that -shows the layers that are in your ``bblayers.conf`` file:: - - $ bitbake-layers add-layer meta-scottrif - NOTE: Starting bitbake server... - Parsing recipes: 100% |##########################################################| Time: 0:00:49 - Parsing of 1441 .bb files complete (0 cached, 1441 parsed). 2055 targets, 56 skipped, 0 masked, 0 errors. - $ bitbake-layers show-layers - NOTE: Starting bitbake server... - layer path priority - ========================================================================== - meta /home/scottrif/poky/meta 5 - meta-poky /home/scottrif/poky/meta-poky 5 - meta-yocto-bsp /home/scottrif/poky/meta-yocto-bsp 5 - workspace /home/scottrif/poky/build/workspace 99 - meta-scottrif /home/scottrif/poky/build/meta-scottrif 6 - - -Adding the layer to this file -enables the build system to locate the layer during the build. - -.. note:: - - During a build, the OpenEmbedded build system looks in the layers - from the top of the list down to the bottom in that order. - -Customizing Images -================== - -You can customize images to satisfy particular requirements. This -section describes several methods and provides guidelines for each. - -Customizing Images Using ``local.conf`` ---------------------------------------- - -Probably the easiest way to customize an image is to add a package by -way of the ``local.conf`` configuration file. Because it is limited to -local use, this method generally only allows you to add packages and is -not as flexible as creating your own customized image. When you add -packages using local variables this way, you need to realize that these -variable changes are in effect for every build and consequently affect -all images, which might not be what you require. - -To add a package to your image using the local configuration file, use -the :term:`IMAGE_INSTALL` variable with the ``:append`` operator:: - - IMAGE_INSTALL:append = " strace" - -Use of the syntax is important; specifically, the leading space -after the opening quote and before the package name, which is -``strace`` in this example. This space is required since the ``:append`` -operator does not add the space. - -Furthermore, you must use ``:append`` instead of the ``+=`` operator if -you want to avoid ordering issues. The reason for this is because doing -so unconditionally appends to the variable and avoids ordering problems -due to the variable being set in image recipes and ``.bbclass`` files -with operators like ``?=``. Using ``:append`` ensures the operation -takes effect. - -As shown in its simplest use, ``IMAGE_INSTALL:append`` affects all -images. It is possible to extend the syntax so that the variable applies -to a specific image only. Here is an example:: - - IMAGE_INSTALL:append:pn-core-image-minimal = " strace" - -This example adds ``strace`` to the ``core-image-minimal`` image only. - -You can add packages using a similar approach through the -:term:`CORE_IMAGE_EXTRA_INSTALL` variable. If you use this variable, only -``core-image-*`` images are affected. - -Customizing Images Using Custom ``IMAGE_FEATURES`` and ``EXTRA_IMAGE_FEATURES`` -------------------------------------------------------------------------------- - -Another method for customizing your image is to enable or disable -high-level image features by using the -:term:`IMAGE_FEATURES` and -:term:`EXTRA_IMAGE_FEATURES` -variables. Although the functions for both variables are nearly -equivalent, best practices dictate using :term:`IMAGE_FEATURES` from within -a recipe and using :term:`EXTRA_IMAGE_FEATURES` from within your -``local.conf`` file, which is found in the -:term:`Build Directory`. - -To understand how these features work, the best reference is -:ref:`meta/classes/image.bbclass `. -This class lists out the available -:term:`IMAGE_FEATURES` of which most map to package groups while some, such -as ``debug-tweaks`` and ``read-only-rootfs``, resolve as general -configuration settings. - -In summary, the file looks at the contents of the :term:`IMAGE_FEATURES` -variable and then maps or configures the feature accordingly. Based on -this information, the build system automatically adds the appropriate -packages or configurations to the -:term:`IMAGE_INSTALL` variable. -Effectively, you are enabling extra features by extending the class or -creating a custom class for use with specialized image ``.bb`` files. - -Use the :term:`EXTRA_IMAGE_FEATURES` variable from within your local -configuration file. Using a separate area from which to enable features -with this variable helps you avoid overwriting the features in the image -recipe that are enabled with :term:`IMAGE_FEATURES`. The value of -:term:`EXTRA_IMAGE_FEATURES` is added to :term:`IMAGE_FEATURES` within -``meta/conf/bitbake.conf``. - -To illustrate how you can use these variables to modify your image, -consider an example that selects the SSH server. The Yocto Project ships -with two SSH servers you can use with your images: Dropbear and OpenSSH. -Dropbear is a minimal SSH server appropriate for resource-constrained -environments, while OpenSSH is a well-known standard SSH server -implementation. By default, the ``core-image-sato`` image is configured -to use Dropbear. The ``core-image-full-cmdline`` and ``core-image-lsb`` -images both include OpenSSH. The ``core-image-minimal`` image does not -contain an SSH server. - -You can customize your image and change these defaults. Edit the -:term:`IMAGE_FEATURES` variable in your recipe or use the -:term:`EXTRA_IMAGE_FEATURES` in your ``local.conf`` file so that it -configures the image you are working with to include -``ssh-server-dropbear`` or ``ssh-server-openssh``. - -.. note:: - - See the ":ref:`ref-manual/features:image features`" section in the Yocto - Project Reference Manual for a complete list of image features that ship - with the Yocto Project. - -Customizing Images Using Custom .bb Files ------------------------------------------ - -You can also customize an image by creating a custom recipe that defines -additional software as part of the image. The following example shows -the form for the two lines you need:: - - IMAGE_INSTALL = "packagegroup-core-x11-base package1 package2" - inherit core-image - -Defining the software using a custom recipe gives you total control over -the contents of the image. It is important to use the correct names of -packages in the :term:`IMAGE_INSTALL` variable. You must use the -OpenEmbedded notation and not the Debian notation for the names (e.g. -``glibc-dev`` instead of ``libc6-dev``). - -The other method for creating a custom image is to base it on an -existing image. For example, if you want to create an image based on -``core-image-sato`` but add the additional package ``strace`` to the -image, copy the ``meta/recipes-sato/images/core-image-sato.bb`` to a new -``.bb`` and add the following line to the end of the copy:: - - IMAGE_INSTALL += "strace" - -Customizing Images Using Custom Package Groups ----------------------------------------------- - -For complex custom images, the best approach for customizing an image is -to create a custom package group recipe that is used to build the image -or images. A good example of a package group recipe is -``meta/recipes-core/packagegroups/packagegroup-base.bb``. - -If you examine that recipe, you see that the :term:`PACKAGES` variable lists -the package group packages to produce. The ``inherit packagegroup`` -statement sets appropriate default values and automatically adds -``-dev``, ``-dbg``, and ``-ptest`` complementary packages for each -package specified in the :term:`PACKAGES` statement. - -.. note:: - - The ``inherit packagegroup`` line should be located near the top of the - recipe, certainly before the :term:`PACKAGES` statement. - -For each package you specify in :term:`PACKAGES`, you can use :term:`RDEPENDS` -and :term:`RRECOMMENDS` entries to provide a list of packages the parent -task package should contain. You can see examples of these further down -in the ``packagegroup-base.bb`` recipe. - -Here is a short, fabricated example showing the same basic pieces for a -hypothetical packagegroup defined in ``packagegroup-custom.bb``, where -the variable :term:`PN` is the standard way to abbreviate the reference to -the full packagegroup name ``packagegroup-custom``:: - - DESCRIPTION = "My Custom Package Groups" - - inherit packagegroup - - PACKAGES = "\ - ${PN}-apps \ - ${PN}-tools \ - " - - RDEPENDS:${PN}-apps = "\ - dropbear \ - portmap \ - psplash" - - RDEPENDS:${PN}-tools = "\ - oprofile \ - oprofileui-server \ - lttng-tools" - - RRECOMMENDS:${PN}-tools = "\ - kernel-module-oprofile" - -In the previous example, two package group packages are created with -their dependencies and their recommended package dependencies listed: -``packagegroup-custom-apps``, and ``packagegroup-custom-tools``. To -build an image using these package group packages, you need to add -``packagegroup-custom-apps`` and/or ``packagegroup-custom-tools`` to -:term:`IMAGE_INSTALL`. For other forms of image dependencies see the other -areas of this section. - -Customizing an Image Hostname ------------------------------ - -By default, the configured hostname (i.e. ``/etc/hostname``) in an image -is the same as the machine name. For example, if -:term:`MACHINE` equals "qemux86", the -configured hostname written to ``/etc/hostname`` is "qemux86". - -You can customize this name by altering the value of the "hostname" -variable in the ``base-files`` recipe using either an append file or a -configuration file. Use the following in an append file:: - - hostname = "myhostname" - -Use the following in a configuration file:: - - hostname:pn-base-files = "myhostname" - -Changing the default value of the variable "hostname" can be useful in -certain situations. For example, suppose you need to do extensive -testing on an image and you would like to easily identify the image -under test from existing images with typical default hostnames. In this -situation, you could change the default hostname to "testme", which -results in all the images using the name "testme". Once testing is -complete and you do not need to rebuild the image for test any longer, -you can easily reset the default hostname. - -Another point of interest is that if you unset the variable, the image -will have no default hostname in the filesystem. Here is an example that -unsets the variable in a configuration file:: - - hostname:pn-base-files = "" - -Having no default hostname in the filesystem is suitable for -environments that use dynamic hostnames such as virtual machines. - -Writing a New Recipe -==================== - -Recipes (``.bb`` files) are fundamental components in the Yocto Project -environment. Each software component built by the OpenEmbedded build -system requires a recipe to define the component. This section describes -how to create, write, and test a new recipe. - -.. note:: - - For information on variables that are useful for recipes and for - information about recipe naming issues, see the - ":ref:`ref-manual/varlocality:recipes`" section of the Yocto Project - Reference Manual. - -Overview --------- - -The following figure shows the basic process for creating a new recipe. -The remainder of the section provides details for the steps. - -.. image:: figures/recipe-workflow.png - :align: center - -Locate or Automatically Create a Base Recipe --------------------------------------------- - -You can always write a recipe from scratch. However, there are three choices -that can help you quickly get started with a new recipe: - -- ``devtool add``: A command that assists in creating a recipe and an - environment conducive to development. - -- ``recipetool create``: A command provided by the Yocto Project that - automates creation of a base recipe based on the source files. - -- *Existing Recipes:* Location and modification of an existing recipe - that is similar in function to the recipe you need. - -.. note:: - - For information on recipe syntax, see the - ":ref:`dev-manual/common-tasks:recipe syntax`" section. - -Creating the Base Recipe Using ``devtool add`` -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The ``devtool add`` command uses the same logic for auto-creating the -recipe as ``recipetool create``, which is listed below. Additionally, -however, ``devtool add`` sets up an environment that makes it easy for -you to patch the source and to make changes to the recipe as is often -necessary when adding a recipe to build a new piece of software to be -included in a build. - -You can find a complete description of the ``devtool add`` command in -the ":ref:`sdk-manual/extensible:a closer look at \`\`devtool add\`\``" section -in the Yocto Project Application Development and the Extensible Software -Development Kit (eSDK) manual. - -Creating the Base Recipe Using ``recipetool create`` -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -``recipetool create`` automates creation of a base recipe given a set of -source code files. As long as you can extract or point to the source -files, the tool will construct a recipe and automatically configure all -pre-build information into the recipe. For example, suppose you have an -application that builds using Autotools. Creating the base recipe using -``recipetool`` results in a recipe that has the pre-build dependencies, -license requirements, and checksums configured. - -To run the tool, you just need to be in your -:term:`Build Directory` and have sourced the -build environment setup script (i.e. -:ref:`structure-core-script`). -To get help on the tool, use the following command:: - - $ recipetool -h - NOTE: Starting bitbake server... - usage: recipetool [-d] [-q] [--color COLOR] [-h] ... - - OpenEmbedded recipe tool - - options: - -d, --debug Enable debug output - -q, --quiet Print only errors - --color COLOR Colorize output (where COLOR is auto, always, never) - -h, --help show this help message and exit - - subcommands: - create Create a new recipe - newappend Create a bbappend for the specified target in the specified - layer - setvar Set a variable within a recipe - appendfile Create/update a bbappend to replace a target file - appendsrcfiles Create/update a bbappend to add or replace source files - appendsrcfile Create/update a bbappend to add or replace a source file - Use recipetool --help to get help on a specific command - -Running ``recipetool create -o OUTFILE`` creates the base recipe and -locates it properly in the layer that contains your source files. -Following are some syntax examples: - - - Use this syntax to generate a recipe based on source. Once generated, - the recipe resides in the existing source code layer:: - - recipetool create -o OUTFILE source - - - Use this syntax to generate a recipe using code that - you extract from source. The extracted code is placed in its own layer - defined by :term:`EXTERNALSRC`. - :: - - recipetool create -o OUTFILE -x EXTERNALSRC source - - - Use this syntax to generate a recipe based on source. The options - direct ``recipetool`` to generate debugging information. Once generated, - the recipe resides in the existing source code layer:: - - recipetool create -d -o OUTFILE source - -Locating and Using a Similar Recipe -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Before writing a recipe from scratch, it is often useful to discover -whether someone else has already written one that meets (or comes close -to meeting) your needs. The Yocto Project and OpenEmbedded communities -maintain many recipes that might be candidates for what you are doing. -You can find a good central index of these recipes in the -:oe_layerindex:`OpenEmbedded Layer Index <>`. - -Working from an existing recipe or a skeleton recipe is the best way to -get started. Here are some points on both methods: - -- *Locate and modify a recipe that is close to what you want to do:* - This method works when you are familiar with the current recipe - space. The method does not work so well for those new to the Yocto - Project or writing recipes. - - Some risks associated with this method are using a recipe that has - areas totally unrelated to what you are trying to accomplish with - your recipe, not recognizing areas of the recipe that you might have - to add from scratch, and so forth. All these risks stem from - unfamiliarity with the existing recipe space. - -- *Use and modify the following skeleton recipe:* If for some reason - you do not want to use ``recipetool`` and you cannot find an existing - recipe that is close to meeting your needs, you can use the following - structure to provide the fundamental areas of a new recipe. - :: - - DESCRIPTION = "" - HOMEPAGE = "" - LICENSE = "" - SECTION = "" - DEPENDS = "" - LIC_FILES_CHKSUM = "" - - SRC_URI = "" - -Storing and Naming the Recipe ------------------------------ - -Once you have your base recipe, you should put it in your own layer and -name it appropriately. Locating it correctly ensures that the -OpenEmbedded build system can find it when you use BitBake to process -the recipe. - -- *Storing Your Recipe:* The OpenEmbedded build system locates your - recipe through the layer's ``conf/layer.conf`` file and the - :term:`BBFILES` variable. This - variable sets up a path from which the build system can locate - recipes. Here is the typical use:: - - BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \ - ${LAYERDIR}/recipes-*/*/*.bbappend" - - Consequently, you need to be sure you locate your new recipe inside - your layer such that it can be found. - - You can find more information on how layers are structured in the - ":ref:`dev-manual/common-tasks:understanding and creating layers`" section. - -- *Naming Your Recipe:* When you name your recipe, you need to follow - this naming convention:: - - basename_version.bb - - Use lower-cased characters and do not include the reserved suffixes - ``-native``, ``-cross``, ``-initial``, or ``-dev`` casually (i.e. do not use - them as part of your recipe name unless the string applies). Here are some - examples: - - .. code-block:: none - - cups_1.7.0.bb - gawk_4.0.2.bb - irssi_0.8.16-rc1.bb - -Running a Build on the Recipe ------------------------------ - -Creating a new recipe is usually an iterative process that requires -using BitBake to process the recipe multiple times in order to -progressively discover and add information to the recipe file. - -Assuming you have sourced the build environment setup script (i.e. -:ref:`structure-core-script`) and you are in -the :term:`Build Directory`, use -BitBake to process your recipe. All you need to provide is the -``basename`` of the recipe as described in the previous section:: - - $ bitbake basename - -During the build, the OpenEmbedded build system creates a temporary work -directory for each recipe -(``${``\ :term:`WORKDIR`\ ``}``) -where it keeps extracted source files, log files, intermediate -compilation and packaging files, and so forth. - -The path to the per-recipe temporary work directory depends on the -context in which it is being built. The quickest way to find this path -is to have BitBake return it by running the following:: - - $ bitbake -e basename | grep ^WORKDIR= - -As an example, assume a Source Directory -top-level folder named ``poky``, a default Build Directory at -``poky/build``, and a ``qemux86-poky-linux`` machine target system. -Furthermore, suppose your recipe is named ``foo_1.3.0.bb``. In this -case, the work directory the build system uses to build the package -would be as follows:: - - poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0 - -Inside this directory you can find sub-directories such as ``image``, -``packages-split``, and ``temp``. After the build, you can examine these -to determine how well the build went. - -.. note:: - - You can find log files for each task in the recipe's ``temp`` - directory (e.g. ``poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0/temp``). - Log files are named ``log.taskname`` (e.g. ``log.do_configure``, - ``log.do_fetch``, and ``log.do_compile``). - -You can find more information about the build process in -":doc:`/overview-manual/development-environment`" -chapter of the Yocto Project Overview and Concepts Manual. - -Fetching Code -------------- - -The first thing your recipe must do is specify how to fetch the source -files. Fetching is controlled mainly through the -:term:`SRC_URI` variable. Your recipe -must have a :term:`SRC_URI` variable that points to where the source is -located. For a graphical representation of source locations, see the -":ref:`overview-manual/concepts:sources`" section in -the Yocto Project Overview and Concepts Manual. - -The :ref:`ref-tasks-fetch` task uses -the prefix of each entry in the :term:`SRC_URI` variable value to determine -which :ref:`fetcher ` to use to get your -source files. It is the :term:`SRC_URI` variable that triggers the fetcher. -The :ref:`ref-tasks-patch` task uses -the variable after source is fetched to apply patches. The OpenEmbedded -build system uses -:term:`FILESOVERRIDES` for -scanning directory locations for local files in :term:`SRC_URI`. - -The :term:`SRC_URI` variable in your recipe must define each unique location -for your source files. It is good practice to not hard-code version -numbers in a URL used in :term:`SRC_URI`. Rather than hard-code these -values, use ``${``\ :term:`PV`\ ``}``, -which causes the fetch process to use the version specified in the -recipe filename. Specifying the version in this manner means that -upgrading the recipe to a future version is as simple as renaming the -recipe to match the new version. - -Here is a simple example from the -``meta/recipes-devtools/strace/strace_5.5.bb`` recipe where the source -comes from a single tarball. Notice the use of the -:term:`PV` variable:: - - SRC_URI = "https://strace.io/files/${PV}/strace-${PV}.tar.xz \ - -Files mentioned in :term:`SRC_URI` whose names end in a typical archive -extension (e.g. ``.tar``, ``.tar.gz``, ``.tar.bz2``, ``.zip``, and so -forth), are automatically extracted during the -:ref:`ref-tasks-unpack` task. For -another example that specifies these types of files, see the -":ref:`dev-manual/common-tasks:autotooled package`" section. - -Another way of specifying source is from an SCM. For Git repositories, -you must specify :term:`SRCREV` and you should specify :term:`PV` to include -the revision with :term:`SRCPV`. Here is an example from the recipe -``meta/recipes-core/musl/gcompat_git.bb``:: - - SRC_URI = "git://git.adelielinux.org/adelie/gcompat.git;protocol=https;branch=current" - - PV = "1.0.0+1.1+git${SRCPV}" - SRCREV = "af5a49e489fdc04b9cf02547650d7aeaccd43793" - -If your :term:`SRC_URI` statement includes URLs pointing to individual files -fetched from a remote server other than a version control system, -BitBake attempts to verify the files against checksums defined in your -recipe to ensure they have not been tampered with or otherwise modified -since the recipe was written. Two checksums are used: -``SRC_URI[md5sum]`` and ``SRC_URI[sha256sum]``. - -If your :term:`SRC_URI` variable points to more than a single URL (excluding -SCM URLs), you need to provide the ``md5`` and ``sha256`` checksums for -each URL. For these cases, you provide a name for each URL as part of -the :term:`SRC_URI` and then reference that name in the subsequent checksum -statements. Here is an example combining lines from the files -``git.inc`` and ``git_2.24.1.bb``:: - - SRC_URI = "${KERNELORG_MIRROR}/software/scm/git/git-${PV}.tar.gz;name=tarball \ - ${KERNELORG_MIRROR}/software/scm/git/git-manpages-${PV}.tar.gz;name=manpages" - - SRC_URI[tarball.md5sum] = "166bde96adbbc11c8843d4f8f4f9811b" - SRC_URI[tarball.sha256sum] = "ad5334956301c86841eb1e5b1bb20884a6bad89a10a6762c958220c7cf64da02" - SRC_URI[manpages.md5sum] = "31c2272a8979022497ba3d4202df145d" - SRC_URI[manpages.sha256sum] = "9a7ae3a093bea39770eb96ca3e5b40bff7af0b9f6123f089d7821d0e5b8e1230" - -Proper values for ``md5`` and ``sha256`` checksums might be available -with other signatures on the download page for the upstream source (e.g. -``md5``, ``sha1``, ``sha256``, ``GPG``, and so forth). Because the -OpenEmbedded build system only deals with ``sha256sum`` and ``md5sum``, -you should verify all the signatures you find by hand. - -If no :term:`SRC_URI` checksums are specified when you attempt to build the -recipe, or you provide an incorrect checksum, the build will produce an -error for each missing or incorrect checksum. As part of the error -message, the build system provides the checksum string corresponding to -the fetched file. Once you have the correct checksums, you can copy and -paste them into your recipe and then run the build again to continue. - -.. note:: - - As mentioned, if the upstream source provides signatures for - verifying the downloaded source code, you should verify those - manually before setting the checksum values in the recipe and - continuing with the build. - -This final example is a bit more complicated and is from the -``meta/recipes-sato/rxvt-unicode/rxvt-unicode_9.20.bb`` recipe. The -example's :term:`SRC_URI` statement identifies multiple files as the source -files for the recipe: a tarball, a patch file, a desktop file, and an -icon. -:: - - SRC_URI = "http://dist.schmorp.de/rxvt-unicode/Attic/rxvt-unicode-${PV}.tar.bz2 \ - file://xwc.patch \ - file://rxvt.desktop \ - file://rxvt.png" - -When you specify local files using the ``file://`` URI protocol, the -build system fetches files from the local machine. The path is relative -to the :term:`FILESPATH` variable -and searches specific directories in a certain order: -``${``\ :term:`BP`\ ``}``, -``${``\ :term:`BPN`\ ``}``, and -``files``. The directories are assumed to be subdirectories of the -directory in which the recipe or append file resides. For another -example that specifies these types of files, see the -":ref:`dev-manual/common-tasks:single .c file package (hello world!)`" section. - -The previous example also specifies a patch file. Patch files are files -whose names usually end in ``.patch`` or ``.diff`` but can end with -compressed suffixes such as ``diff.gz`` and ``patch.bz2``, for example. -The build system automatically applies patches as described in the -":ref:`dev-manual/common-tasks:patching code`" section. - -Fetching Code Through Firewalls -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Some users are behind firewalls and need to fetch code through a proxy. -See the ":doc:`/ref-manual/faq`" chapter for advice. - -Limiting the Number of Parallel Connections -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Some users are behind firewalls or use servers where the number of parallel -connections is limited. In such cases, you can limit the number of fetch -tasks being run in parallel by adding the following to your ``local.conf`` -file:: - - do_fetch[number_threads] = "4" - -Unpacking Code --------------- - -During the build, the -:ref:`ref-tasks-unpack` task unpacks -the source with ``${``\ :term:`S`\ ``}`` -pointing to where it is unpacked. - -If you are fetching your source files from an upstream source archived -tarball and the tarball's internal structure matches the common -convention of a top-level subdirectory named -``${``\ :term:`BPN`\ ``}-${``\ :term:`PV`\ ``}``, -then you do not need to set :term:`S`. However, if :term:`SRC_URI` specifies to -fetch source from an archive that does not use this convention, or from -an SCM like Git or Subversion, your recipe needs to define :term:`S`. - -If processing your recipe using BitBake successfully unpacks the source -files, you need to be sure that the directory pointed to by ``${S}`` -matches the structure of the source. - -Patching Code -------------- - -Sometimes it is necessary to patch code after it has been fetched. Any -files mentioned in :term:`SRC_URI` whose names end in ``.patch`` or -``.diff`` or compressed versions of these suffixes (e.g. ``diff.gz`` are -treated as patches. The -:ref:`ref-tasks-patch` task -automatically applies these patches. - -The build system should be able to apply patches with the "-p1" option -(i.e. one directory level in the path will be stripped off). If your -patch needs to have more directory levels stripped off, specify the -number of levels using the "striplevel" option in the :term:`SRC_URI` entry -for the patch. Alternatively, if your patch needs to be applied in a -specific subdirectory that is not specified in the patch file, use the -"patchdir" option in the entry. - -As with all local files referenced in -:term:`SRC_URI` using ``file://``, -you should place patch files in a directory next to the recipe either -named the same as the base name of the recipe -(:term:`BP` and -:term:`BPN`) or "files". - -Licensing ---------- - -Your recipe needs to have both the -:term:`LICENSE` and -:term:`LIC_FILES_CHKSUM` -variables: - -- :term:`LICENSE`: This variable specifies the license for the software. - If you do not know the license under which the software you are - building is distributed, you should go to the source code and look - for that information. Typical files containing this information - include ``COPYING``, :term:`LICENSE`, and ``README`` files. You could - also find the information near the top of a source file. For example, - given a piece of software licensed under the GNU General Public - License version 2, you would set :term:`LICENSE` as follows:: - - LICENSE = "GPL-2.0-only" - - The licenses you specify within :term:`LICENSE` can have any name as long - as you do not use spaces, since spaces are used as separators between - license names. For standard licenses, use the names of the files in - ``meta/files/common-licenses/`` or the :term:`SPDXLICENSEMAP` flag names - defined in ``meta/conf/licenses.conf``. - -- :term:`LIC_FILES_CHKSUM`: The OpenEmbedded build system uses this - variable to make sure the license text has not changed. If it has, - the build produces an error and it affords you the chance to figure - it out and correct the problem. - - You need to specify all applicable licensing files for the software. - At the end of the configuration step, the build process will compare - the checksums of the files to be sure the text has not changed. Any - differences result in an error with the message containing the - current checksum. For more explanation and examples of how to set the - :term:`LIC_FILES_CHKSUM` variable, see the - ":ref:`dev-manual/common-tasks:tracking license changes`" section. - - To determine the correct checksum string, you can list the - appropriate files in the :term:`LIC_FILES_CHKSUM` variable with incorrect - md5 strings, attempt to build the software, and then note the - resulting error messages that will report the correct md5 strings. - See the ":ref:`dev-manual/common-tasks:fetching code`" section for - additional information. - - Here is an example that assumes the software has a ``COPYING`` file:: - - LIC_FILES_CHKSUM = "file://COPYING;md5=xxx" - - When you try to build the - software, the build system will produce an error and give you the - correct string that you can substitute into the recipe file for a - subsequent build. - -Dependencies ------------- - -Most software packages have a short list of other packages that they -require, which are called dependencies. These dependencies fall into two -main categories: build-time dependencies, which are required when the -software is built; and runtime dependencies, which are required to be -installed on the target in order for the software to run. - -Within a recipe, you specify build-time dependencies using the -:term:`DEPENDS` variable. Although there are nuances, -items specified in :term:`DEPENDS` should be names of other -recipes. It is important that you specify all build-time dependencies -explicitly. - -Another consideration is that configure scripts might automatically -check for optional dependencies and enable corresponding functionality -if those dependencies are found. If you wish to make a recipe that is -more generally useful (e.g. publish the recipe in a layer for others to -use), instead of hard-disabling the functionality, you can use the -:term:`PACKAGECONFIG` variable to allow functionality and the -corresponding dependencies to be enabled and disabled easily by other -users of the recipe. - -Similar to build-time dependencies, you specify runtime dependencies -through a variable - -:term:`RDEPENDS`, which is -package-specific. All variables that are package-specific need to have -the name of the package added to the end as an override. Since the main -package for a recipe has the same name as the recipe, and the recipe's -name can be found through the -``${``\ :term:`PN`\ ``}`` variable, then -you specify the dependencies for the main package by setting -``RDEPENDS:${PN}``. If the package were named ``${PN}-tools``, then you -would set ``RDEPENDS:${PN}-tools``, and so forth. - -Some runtime dependencies will be set automatically at packaging time. -These dependencies include any shared library dependencies (i.e. if a -package "example" contains "libexample" and another package "mypackage" -contains a binary that links to "libexample" then the OpenEmbedded build -system will automatically add a runtime dependency to "mypackage" on -"example"). See the -":ref:`overview-manual/concepts:automatically added runtime dependencies`" -section in the Yocto Project Overview and Concepts Manual for further -details. - -Configuring the Recipe ----------------------- - -Most software provides some means of setting build-time configuration -options before compilation. Typically, setting these options is -accomplished by running a configure script with options, or by modifying -a build configuration file. - -.. note:: - - As of Yocto Project Release 1.7, some of the core recipes that - package binary configuration scripts now disable the scripts due to - the scripts previously requiring error-prone path substitution. The - OpenEmbedded build system uses ``pkg-config`` now, which is much more - robust. You can find a list of the ``*-config`` scripts that are disabled - in the ":ref:`migration-1.7-binary-configuration-scripts-disabled`" section - in the Yocto Project Reference Manual. - -A major part of build-time configuration is about checking for -build-time dependencies and possibly enabling optional functionality as -a result. You need to specify any build-time dependencies for the -software you are building in your recipe's -:term:`DEPENDS` value, in terms of -other recipes that satisfy those dependencies. You can often find -build-time or runtime dependencies described in the software's -documentation. - -The following list provides configuration items of note based on how -your software is built: - -- *Autotools:* If your source files have a ``configure.ac`` file, then - your software is built using Autotools. If this is the case, you just - need to modify the configuration. - - When using Autotools, your recipe needs to inherit the - :ref:`autotools ` class - and your recipe does not have to contain a - :ref:`ref-tasks-configure` task. - However, you might still want to make some adjustments. For example, - you can set - :term:`EXTRA_OECONF` or - :term:`PACKAGECONFIG_CONFARGS` - to pass any needed configure options that are specific to the recipe. - -- *CMake:* If your source files have a ``CMakeLists.txt`` file, then - your software is built using CMake. If this is the case, you just - need to modify the configuration. - - When you use CMake, your recipe needs to inherit the - :ref:`cmake ` class and your - recipe does not have to contain a - :ref:`ref-tasks-configure` task. - You can make some adjustments by setting - :term:`EXTRA_OECMAKE` to - pass any needed configure options that are specific to the recipe. - - .. note:: - - If you need to install one or more custom CMake toolchain files - that are supplied by the application you are building, install the - files to ``${D}${datadir}/cmake/Modules`` during ``do_install``. - -- *Other:* If your source files do not have a ``configure.ac`` or - ``CMakeLists.txt`` file, then your software is built using some - method other than Autotools or CMake. If this is the case, you - normally need to provide a - :ref:`ref-tasks-configure` task - in your recipe unless, of course, there is nothing to configure. - - Even if your software is not being built by Autotools or CMake, you - still might not need to deal with any configuration issues. You need - to determine if configuration is even a required step. You might need - to modify a Makefile or some configuration file used for the build to - specify necessary build options. Or, perhaps you might need to run a - provided, custom configure script with the appropriate options. - - For the case involving a custom configure script, you would run - ``./configure --help`` and look for the options you need to set. - -Once configuration succeeds, it is always good practice to look at the -``log.do_configure`` file to ensure that the appropriate options have -been enabled and no additional build-time dependencies need to be added -to :term:`DEPENDS`. For example, if the configure script reports that it -found something not mentioned in :term:`DEPENDS`, or that it did not find -something that it needed for some desired optional functionality, then -you would need to add those to :term:`DEPENDS`. Looking at the log might -also reveal items being checked for, enabled, or both that you do not -want, or items not being found that are in :term:`DEPENDS`, in which case -you would need to look at passing extra options to the configure script -as needed. For reference information on configure options specific to -the software you are building, you can consult the output of the -``./configure --help`` command within ``${S}`` or consult the software's -upstream documentation. - -Using Headers to Interface with Devices ---------------------------------------- - -If your recipe builds an application that needs to communicate with some -device or needs an API into a custom kernel, you will need to provide -appropriate header files. Under no circumstances should you ever modify -the existing -``meta/recipes-kernel/linux-libc-headers/linux-libc-headers.inc`` file. -These headers are used to build ``libc`` and must not be compromised -with custom or machine-specific header information. If you customize -``libc`` through modified headers all other applications that use -``libc`` thus become affected. - -.. note:: - - Never copy and customize the ``libc`` header file (i.e. - ``meta/recipes-kernel/linux-libc-headers/linux-libc-headers.inc``). - -The correct way to interface to a device or custom kernel is to use a -separate package that provides the additional headers for the driver or -other unique interfaces. When doing so, your application also becomes -responsible for creating a dependency on that specific provider. - -Consider the following: - -- Never modify ``linux-libc-headers.inc``. Consider that file to be - part of the ``libc`` system, and not something you use to access the - kernel directly. You should access ``libc`` through specific ``libc`` - calls. - -- Applications that must talk directly to devices should either provide - necessary headers themselves, or establish a dependency on a special - headers package that is specific to that driver. - -For example, suppose you want to modify an existing header that adds I/O -control or network support. If the modifications are used by a small -number programs, providing a unique version of a header is easy and has -little impact. When doing so, bear in mind the guidelines in the -previous list. - -.. note:: - - If for some reason your changes need to modify the behavior of the ``libc``, - and subsequently all other applications on the system, use a ``.bbappend`` - to modify the ``linux-kernel-headers.inc`` file. However, take care to not - make the changes machine specific. - -Consider a case where your kernel is older and you need an older -``libc`` ABI. The headers installed by your recipe should still be a -standard mainline kernel, not your own custom one. - -When you use custom kernel headers you need to get them from -:term:`STAGING_KERNEL_DIR`, -which is the directory with kernel headers that are required to build -out-of-tree modules. Your recipe will also need the following:: - - do_configure[depends] += "virtual/kernel:do_shared_workdir" - -Compilation ------------ - -During a build, the ``do_compile`` task happens after source is fetched, -unpacked, and configured. If the recipe passes through ``do_compile`` -successfully, nothing needs to be done. - -However, if the compile step fails, you need to diagnose the failure. -Here are some common issues that cause failures. - -.. note:: - - For cases where improper paths are detected for configuration files - or for when libraries/headers cannot be found, be sure you are using - the more robust ``pkg-config``. See the note in section - ":ref:`dev-manual/common-tasks:Configuring the Recipe`" for additional information. - -- *Parallel build failures:* These failures manifest themselves as - intermittent errors, or errors reporting that a file or directory - that should be created by some other part of the build process could - not be found. This type of failure can occur even if, upon - inspection, the file or directory does exist after the build has - failed, because that part of the build process happened in the wrong - order. - - To fix the problem, you need to either satisfy the missing dependency - in the Makefile or whatever script produced the Makefile, or (as a - workaround) set :term:`PARALLEL_MAKE` to an empty string:: - - PARALLEL_MAKE = "" - - For information on parallel Makefile issues, see the - ":ref:`dev-manual/common-tasks:debugging parallel make races`" section. - -- *Improper host path usage:* This failure applies to recipes building - for the target or ``nativesdk`` only. The failure occurs when the - compilation process uses improper headers, libraries, or other files - from the host system when cross-compiling for the target. - - To fix the problem, examine the ``log.do_compile`` file to identify - the host paths being used (e.g. ``/usr/include``, ``/usr/lib``, and - so forth) and then either add configure options, apply a patch, or do - both. - -- *Failure to find required libraries/headers:* If a build-time - dependency is missing because it has not been declared in - :term:`DEPENDS`, or because the - dependency exists but the path used by the build process to find the - file is incorrect and the configure step did not detect it, the - compilation process could fail. For either of these failures, the - compilation process notes that files could not be found. In these - cases, you need to go back and add additional options to the - configure script as well as possibly add additional build-time - dependencies to :term:`DEPENDS`. - - Occasionally, it is necessary to apply a patch to the source to - ensure the correct paths are used. If you need to specify paths to - find files staged into the sysroot from other recipes, use the - variables that the OpenEmbedded build system provides (e.g. - :term:`STAGING_BINDIR`, :term:`STAGING_INCDIR`, :term:`STAGING_DATADIR`, and so - forth). - -Installing ----------- - -During ``do_install``, the task copies the built files along with their -hierarchy to locations that would mirror their locations on the target -device. The installation process copies files from the -``${``\ :term:`S`\ ``}``, -``${``\ :term:`B`\ ``}``, and -``${``\ :term:`WORKDIR`\ ``}`` -directories to the ``${``\ :term:`D`\ ``}`` -directory to create the structure as it should appear on the target -system. - -How your software is built affects what you must do to be sure your -software is installed correctly. The following list describes what you -must do for installation depending on the type of build system used by -the software being built: - -- *Autotools and CMake:* If the software your recipe is building uses - Autotools or CMake, the OpenEmbedded build system understands how to - install the software. Consequently, you do not have to have a - ``do_install`` task as part of your recipe. You just need to make - sure the install portion of the build completes with no issues. - However, if you wish to install additional files not already being - installed by ``make install``, you should do this using a - ``do_install:append`` function using the install command as described - in the "Manual" bulleted item later in this list. - -- *Other (using* ``make install``\ *)*: You need to define a ``do_install`` - function in your recipe. The function should call - ``oe_runmake install`` and will likely need to pass in the - destination directory as well. How you pass that path is dependent on - how the ``Makefile`` being run is written (e.g. ``DESTDIR=${D}``, - ``PREFIX=${D}``, ``INSTALLROOT=${D}``, and so forth). - - For an example recipe using ``make install``, see the - ":ref:`dev-manual/common-tasks:makefile-based package`" section. - -- *Manual:* You need to define a ``do_install`` function in your - recipe. The function must first use ``install -d`` to create the - directories under - ``${``\ :term:`D`\ ``}``. Once the - directories exist, your function can use ``install`` to manually - install the built software into the directories. - - You can find more information on ``install`` at - https://www.gnu.org/software/coreutils/manual/html_node/install-invocation.html. - -For the scenarios that do not use Autotools or CMake, you need to track -the installation and diagnose and fix any issues until everything -installs correctly. You need to look in the default location of -``${D}``, which is ``${WORKDIR}/image``, to be sure your files have been -installed correctly. - -.. note:: - - - During the installation process, you might need to modify some of - the installed files to suit the target layout. For example, you - might need to replace hard-coded paths in an initscript with - values of variables provided by the build system, such as - replacing ``/usr/bin/`` with ``${bindir}``. If you do perform such - modifications during ``do_install``, be sure to modify the - destination file after copying rather than before copying. - Modifying after copying ensures that the build system can - re-execute ``do_install`` if needed. - - - ``oe_runmake install``, which can be run directly or can be run - indirectly by the - :ref:`autotools ` and - :ref:`cmake ` classes, - runs ``make install`` in parallel. Sometimes, a Makefile can have - missing dependencies between targets that can result in race - conditions. If you experience intermittent failures during - ``do_install``, you might be able to work around them by disabling - parallel Makefile installs by adding the following to the recipe:: - - PARALLEL_MAKEINST = "" - - See :term:`PARALLEL_MAKEINST` for additional information. - - - If you need to install one or more custom CMake toolchain files - that are supplied by the application you are building, install the - files to ``${D}${datadir}/cmake/Modules`` during - :ref:`ref-tasks-install`. - -Enabling System Services ------------------------- - -If you want to install a service, which is a process that usually starts -on boot and runs in the background, then you must include some -additional definitions in your recipe. - -If you are adding services and the service initialization script or the -service file itself is not installed, you must provide for that -installation in your recipe using a ``do_install:append`` function. If -your recipe already has a ``do_install`` function, update the function -near its end rather than adding an additional ``do_install:append`` -function. - -When you create the installation for your services, you need to -accomplish what is normally done by ``make install``. In other words, -make sure your installation arranges the output similar to how it is -arranged on the target system. - -The OpenEmbedded build system provides support for starting services two -different ways: - -- *SysVinit:* SysVinit is a system and service manager that manages the - init system used to control the very basic functions of your system. - The init program is the first program started by the Linux kernel - when the system boots. Init then controls the startup, running and - shutdown of all other programs. - - To enable a service using SysVinit, your recipe needs to inherit the - :ref:`update-rc.d ` - class. The class helps facilitate safely installing the package on - the target. - - You will need to set the - :term:`INITSCRIPT_PACKAGES`, - :term:`INITSCRIPT_NAME`, - and - :term:`INITSCRIPT_PARAMS` - variables within your recipe. - -- *systemd:* System Management Daemon (systemd) was designed to replace - SysVinit and to provide enhanced management of services. For more - information on systemd, see the systemd homepage at - https://freedesktop.org/wiki/Software/systemd/. - - To enable a service using systemd, your recipe needs to inherit the - :ref:`systemd ` class. See - the ``systemd.bbclass`` file located in your :term:`Source Directory` - section for - more information. - -Packaging ---------- - -Successful packaging is a combination of automated processes performed -by the OpenEmbedded build system and some specific steps you need to -take. The following list describes the process: - -- *Splitting Files*: The ``do_package`` task splits the files produced - by the recipe into logical components. Even software that produces a - single binary might still have debug symbols, documentation, and - other logical components that should be split out. The ``do_package`` - task ensures that files are split up and packaged correctly. - -- *Running QA Checks*: The - :ref:`insane ` class adds a - step to the package generation process so that output quality - assurance checks are generated by the OpenEmbedded build system. This - step performs a range of checks to be sure the build's output is free - of common problems that show up during runtime. For information on - these checks, see the - :ref:`insane ` class and - the ":ref:`ref-manual/qa-checks:qa error and warning messages`" - chapter in the Yocto Project Reference Manual. - -- *Hand-Checking Your Packages*: After you build your software, you - need to be sure your packages are correct. Examine the - ``${``\ :term:`WORKDIR`\ ``}/packages-split`` - directory and make sure files are where you expect them to be. If you - discover problems, you can set - :term:`PACKAGES`, - :term:`FILES`, - ``do_install(:append)``, and so forth as needed. - -- *Splitting an Application into Multiple Packages*: If you need to - split an application into several packages, see the - ":ref:`dev-manual/common-tasks:splitting an application into multiple packages`" - section for an example. - -- *Installing a Post-Installation Script*: For an example showing how - to install a post-installation script, see the - ":ref:`dev-manual/common-tasks:post-installation scripts`" section. - -- *Marking Package Architecture*: Depending on what your recipe is - building and how it is configured, it might be important to mark the - packages produced as being specific to a particular machine, or to - mark them as not being specific to a particular machine or - architecture at all. - - By default, packages apply to any machine with the same architecture - as the target machine. When a recipe produces packages that are - machine-specific (e.g. the - :term:`MACHINE` value is passed - into the configure script or a patch is applied only for a particular - machine), you should mark them as such by adding the following to the - recipe:: - - PACKAGE_ARCH = "${MACHINE_ARCH}" - - On the other hand, if the recipe produces packages that do not - contain anything specific to the target machine or architecture at - all (e.g. recipes that simply package script files or configuration - files), you should use the - :ref:`allarch ` class to - do this for you by adding this to your recipe:: - - inherit allarch - - Ensuring that the package architecture is correct is not critical - while you are doing the first few builds of your recipe. However, it - is important in order to ensure that your recipe rebuilds (or does - not rebuild) appropriately in response to changes in configuration, - and to ensure that you get the appropriate packages installed on the - target machine, particularly if you run separate builds for more than - one target machine. - -Sharing Files Between Recipes ------------------------------ - -Recipes often need to use files provided by other recipes on the build -host. For example, an application linking to a common library needs -access to the library itself and its associated headers. The way this -access is accomplished is by populating a sysroot with files. Each -recipe has two sysroots in its work directory, one for target files -(``recipe-sysroot``) and one for files that are native to the build host -(``recipe-sysroot-native``). - -.. note:: - - You could find the term "staging" used within the Yocto project - regarding files populating sysroots (e.g. the :term:`STAGING_DIR` - variable). - -Recipes should never populate the sysroot directly (i.e. write files -into sysroot). Instead, files should be installed into standard -locations during the -:ref:`ref-tasks-install` task within -the ``${``\ :term:`D`\ ``}`` directory. The -reason for this limitation is that almost all files that populate the -sysroot are cataloged in manifests in order to ensure the files can be -removed later when a recipe is either modified or removed. Thus, the -sysroot is able to remain free from stale files. - -A subset of the files installed by the :ref:`ref-tasks-install` task are -used by the :ref:`ref-tasks-populate_sysroot` task as defined by the the -:term:`SYSROOT_DIRS` variable to automatically populate the sysroot. It -is possible to modify the list of directories that populate the sysroot. -The following example shows how you could add the ``/opt`` directory to -the list of directories within a recipe:: - - SYSROOT_DIRS += "/opt" - -.. note:: - - The `/sysroot-only` is to be used by recipes that generate artifacts - that are not included in the target filesystem, allowing them to share - these artifacts without needing to use the :term:`DEPLOY_DIR`. - -For a more complete description of the :ref:`ref-tasks-populate_sysroot` -task and its associated functions, see the -:ref:`staging ` class. - -Using Virtual Providers ------------------------ - -Prior to a build, if you know that several different recipes provide the -same functionality, you can use a virtual provider (i.e. ``virtual/*``) -as a placeholder for the actual provider. The actual provider is -determined at build-time. - -A common scenario where a virtual provider is used would be for the -kernel recipe. Suppose you have three kernel recipes whose -:term:`PN` values map to ``kernel-big``, -``kernel-mid``, and ``kernel-small``. Furthermore, each of these recipes -in some way uses a :term:`PROVIDES` -statement that essentially identifies itself as being able to provide -``virtual/kernel``. Here is one way through the -:ref:`kernel ` class:: - - PROVIDES += "virtual/kernel" - -Any recipe that inherits the :ref:`kernel ` class is -going to utilize a :term:`PROVIDES` statement that identifies that recipe as -being able to provide the ``virtual/kernel`` item. - -Now comes the time to actually build an image and you need a kernel -recipe, but which one? You can configure your build to call out the -kernel recipe you want by using the :term:`PREFERRED_PROVIDER` variable. As -an example, consider the :yocto_git:`x86-base.inc -` include file, which is a -machine (i.e. :term:`MACHINE`) configuration file. This include file is the -reason all x86-based machines use the ``linux-yocto`` kernel. Here are the -relevant lines from the include file:: - - PREFERRED_PROVIDER_virtual/kernel ??= "linux-yocto" - PREFERRED_VERSION_linux-yocto ??= "4.15%" - -When you use a virtual provider, you do not have to "hard code" a recipe -name as a build dependency. You can use the -:term:`DEPENDS` variable to state the -build is dependent on ``virtual/kernel`` for example:: - - DEPENDS = "virtual/kernel" - -During the build, the OpenEmbedded build system picks -the correct recipe needed for the ``virtual/kernel`` dependency based on -the :term:`PREFERRED_PROVIDER` variable. If you want to use the small kernel -mentioned at the beginning of this section, configure your build as -follows:: - - PREFERRED_PROVIDER_virtual/kernel ??= "kernel-small" - -.. note:: - - Any recipe that :term:`PROVIDES` a ``virtual/*`` item that is ultimately not - selected through :term:`PREFERRED_PROVIDER` does not get built. Preventing these - recipes from building is usually the desired behavior since this mechanism's - purpose is to select between mutually exclusive alternative providers. - -The following lists specific examples of virtual providers: - -- ``virtual/kernel``: Provides the name of the kernel recipe to use - when building a kernel image. - -- ``virtual/bootloader``: Provides the name of the bootloader to use - when building an image. - -- ``virtual/libgbm``: Provides ``gbm.pc``. - -- ``virtual/egl``: Provides ``egl.pc`` and possibly ``wayland-egl.pc``. - -- ``virtual/libgl``: Provides ``gl.pc`` (i.e. libGL). - -- ``virtual/libgles1``: Provides ``glesv1_cm.pc`` (i.e. libGLESv1_CM). - -- ``virtual/libgles2``: Provides ``glesv2.pc`` (i.e. libGLESv2). - -.. note:: - - Virtual providers only apply to build time dependencies specified with - :term:`PROVIDES` and :term:`DEPENDS`. They do not apply to runtime - dependencies specified with :term:`RPROVIDES` and :term:`RDEPENDS`. - -Properly Versioning Pre-Release Recipes ---------------------------------------- - -Sometimes the name of a recipe can lead to versioning problems when the -recipe is upgraded to a final release. For example, consider the -``irssi_0.8.16-rc1.bb`` recipe file in the list of example recipes in -the ":ref:`dev-manual/common-tasks:storing and naming the recipe`" section. -This recipe is at a release candidate stage (i.e. "rc1"). When the recipe is -released, the recipe filename becomes ``irssi_0.8.16.bb``. The version -change from ``0.8.16-rc1`` to ``0.8.16`` is seen as a decrease by the -build system and package managers, so the resulting packages will not -correctly trigger an upgrade. - -In order to ensure the versions compare properly, the recommended -convention is to set :term:`PV` within the -recipe to "previous_version+current_version". You can use an additional -variable so that you can use the current version elsewhere. Here is an -example:: - - REALPV = "0.8.16-rc1" - PV = "0.8.15+${REALPV}" - -Post-Installation Scripts -------------------------- - -Post-installation scripts run immediately after installing a package on -the target or during image creation when a package is included in an -image. To add a post-installation script to a package, add a -``pkg_postinst:``\ `PACKAGENAME`\ ``()`` function to the recipe file -(``.bb``) and replace `PACKAGENAME` with the name of the package you want -to attach to the ``postinst`` script. To apply the post-installation -script to the main package for the recipe, which is usually what is -required, specify -``${``\ :term:`PN`\ ``}`` in place of -PACKAGENAME. - -A post-installation function has the following structure:: - - pkg_postinst:PACKAGENAME() { - # Commands to carry out - } - -The script defined in the post-installation function is called when the -root filesystem is created. If the script succeeds, the package is -marked as installed. - -.. note:: - - Any RPM post-installation script that runs on the target should - return a 0 exit code. RPM does not allow non-zero exit codes for - these scripts, and the RPM package manager will cause the package to - fail installation on the target. - -Sometimes it is necessary for the execution of a post-installation -script to be delayed until the first boot. For example, the script might -need to be executed on the device itself. To delay script execution -until boot time, you must explicitly mark post installs to defer to the -target. You can use ``pkg_postinst_ontarget()`` or call -``postinst_intercept delay_to_first_boot`` from ``pkg_postinst()``. Any -failure of a ``pkg_postinst()`` script (including exit 1) triggers an -error during the -:ref:`ref-tasks-rootfs` task. - -If you have recipes that use ``pkg_postinst`` function and they require -the use of non-standard native tools that have dependencies during -root filesystem construction, you need to use the -:term:`PACKAGE_WRITE_DEPS` -variable in your recipe to list these tools. If you do not use this -variable, the tools might be missing and execution of the -post-installation script is deferred until first boot. Deferring the -script to the first boot is undesirable and impossible for read-only -root filesystems. - -.. note:: - - There is equivalent support for pre-install, pre-uninstall, and post-uninstall - scripts by way of ``pkg_preinst``, ``pkg_prerm``, and ``pkg_postrm``, - respectively. These scrips work in exactly the same way as does - ``pkg_postinst`` with the exception that they run at different times. Also, - because of when they run, they are not applicable to being run at image - creation time like ``pkg_postinst``. - -Testing -------- - -The final step for completing your recipe is to be sure that the -software you built runs correctly. To accomplish runtime testing, add -the build's output packages to your image and test them on the target. - -For information on how to customize your image by adding specific -packages, see ":ref:`dev-manual/common-tasks:customizing images`" section. - -Examples --------- - -To help summarize how to write a recipe, this section provides some -examples given various scenarios: - -- Recipes that use local files - -- Using an Autotooled package - -- Using a Makefile-based package - -- Splitting an application into multiple packages - -- Adding binaries to an image - -Single .c File Package (Hello World!) -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Building an application from a single file that is stored locally (e.g. -under ``files``) requires a recipe that has the file listed in the -:term:`SRC_URI` variable. Additionally, you need to manually write the -``do_compile`` and ``do_install`` tasks. The :term:`S` variable defines the -directory containing the source code, which is set to -:term:`WORKDIR` in this case - the -directory BitBake uses for the build. -:: - - SUMMARY = "Simple helloworld application" - SECTION = "examples" - LICENSE = "MIT" - LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302" - - SRC_URI = "file://helloworld.c" - - S = "${WORKDIR}" - - do_compile() { - ${CC} ${LDFLAGS} helloworld.c -o helloworld - } - - do_install() { - install -d ${D}${bindir} - install -m 0755 helloworld ${D}${bindir} - } - -By default, the ``helloworld``, ``helloworld-dbg``, and -``helloworld-dev`` packages are built. For information on how to -customize the packaging process, see the -":ref:`dev-manual/common-tasks:splitting an application into multiple packages`" -section. - -Autotooled Package -~~~~~~~~~~~~~~~~~~ - -Applications that use Autotools such as ``autoconf`` and ``automake`` -require a recipe that has a source archive listed in :term:`SRC_URI` and -also inherit the -:ref:`autotools ` class, -which contains the definitions of all the steps needed to build an -Autotool-based application. The result of the build is automatically -packaged. And, if the application uses NLS for localization, packages -with local information are generated (one package per language). -Following is one example: (``hello_2.3.bb``) -:: - - SUMMARY = "GNU Helloworld application" - SECTION = "examples" - LICENSE = "GPL-2.0-or-later" - LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe" - - SRC_URI = "${GNU_MIRROR}/hello/hello-${PV}.tar.gz" - - inherit autotools gettext - -The variable :term:`LIC_FILES_CHKSUM` is used to track source license -changes as described in the -":ref:`dev-manual/common-tasks:tracking license changes`" section in -the Yocto Project Overview and Concepts Manual. You can quickly create -Autotool-based recipes in a manner similar to the previous example. - -Makefile-Based Package -~~~~~~~~~~~~~~~~~~~~~~ - -Applications that use GNU ``make`` also require a recipe that has the -source archive listed in :term:`SRC_URI`. You do not need to add a -``do_compile`` step since by default BitBake starts the ``make`` command -to compile the application. If you need additional ``make`` options, you -should store them in the -:term:`EXTRA_OEMAKE` or -:term:`PACKAGECONFIG_CONFARGS` -variables. BitBake passes these options into the GNU ``make`` -invocation. Note that a ``do_install`` task is still required. -Otherwise, BitBake runs an empty ``do_install`` task by default. - -Some applications might require extra parameters to be passed to the -compiler. For example, the application might need an additional header -path. You can accomplish this by adding to the :term:`CFLAGS` variable. The -following example shows this:: - - CFLAGS:prepend = "-I ${S}/include " - -In the following example, ``lz4`` is a makefile-based package:: - - SUMMARY = "Extremely Fast Compression algorithm" - DESCRIPTION = "LZ4 is a very fast lossless compression algorithm, providing compression speed at 400 MB/s per core, scalable with multi-cores CPU. It also features an extremely fast decoder, with speed in multiple GB/s per core, typically reaching RAM speed limits on multi-core systems." - HOMEPAGE = "https://github.com/lz4/lz4" - - LICENSE = "BSD-2-Clause | GPL-2.0-only" - LIC_FILES_CHKSUM = "file://lib/LICENSE;md5=ebc2ea4814a64de7708f1571904b32cc \ - file://programs/COPYING;md5=b234ee4d69f5fce4486a80fdaf4a4263 \ - file://LICENSE;md5=d57c0d21cb917fb4e0af2454aa48b956 \ - " - - PE = "1" - - SRCREV = "d44371841a2f1728a3f36839fd4b7e872d0927d3" - - SRC_URI = "git://github.com/lz4/lz4.git;branch=release;protocol=https \ - file://CVE-2021-3520.patch \ - " - UPSTREAM_CHECK_GITTAGREGEX = "v(?P.*)" - - S = "${WORKDIR}/git" - - # Fixed in r118, which is larger than the current version. - CVE_CHECK_IGNORE += "CVE-2014-4715" - - EXTRA_OEMAKE = "PREFIX=${prefix} CC='${CC}' CFLAGS='${CFLAGS}' DESTDIR=${D} LIBDIR=${libdir} INCLUDEDIR=${includedir} BUILD_STATIC=no" - - do_install() { - oe_runmake install - } - - BBCLASSEXTEND = "native nativesdk" - -Splitting an Application into Multiple Packages -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -You can use the variables :term:`PACKAGES` and :term:`FILES` to split an -application into multiple packages. - -Following is an example that uses the ``libxpm`` recipe. By default, -this recipe generates a single package that contains the library along -with a few binaries. You can modify the recipe to split the binaries -into separate packages:: - - require xorg-lib-common.inc - - SUMMARY = "Xpm: X Pixmap extension library" - LICENSE = "MIT" - LIC_FILES_CHKSUM = "file://COPYING;md5=51f4270b012ecd4ab1a164f5f4ed6cf7" - DEPENDS += "libxext libsm libxt" - PE = "1" - - XORG_PN = "libXpm" - - PACKAGES =+ "sxpm cxpm" - FILES:cxpm = "${bindir}/cxpm" - FILES:sxpm = "${bindir}/sxpm" - -In the previous example, we want to ship the ``sxpm`` and ``cxpm`` -binaries in separate packages. Since ``bindir`` would be packaged into -the main :term:`PN` package by default, we prepend the :term:`PACKAGES` variable -so additional package names are added to the start of list. This results -in the extra ``FILES:*`` variables then containing information that -define which files and directories go into which packages. Files -included by earlier packages are skipped by latter packages. Thus, the -main :term:`PN` package does not include the above listed files. - -Packaging Externally Produced Binaries -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Sometimes, you need to add pre-compiled binaries to an image. For -example, suppose that there are binaries for proprietary code, -created by a particular division of a company. Your part of the company -needs to use those binaries as part of an image that you are building -using the OpenEmbedded build system. Since you only have the binaries -and not the source code, you cannot use a typical recipe that expects to -fetch the source specified in -:term:`SRC_URI` and then compile it. - -One method is to package the binaries and then install them as part of -the image. Generally, it is not a good idea to package binaries since, -among other things, it can hinder the ability to reproduce builds and -could lead to compatibility problems with ABI in the future. However, -sometimes you have no choice. - -The easiest solution is to create a recipe that uses the -:ref:`bin_package ` class -and to be sure that you are using default locations for build artifacts. -In most cases, the :ref:`bin_package ` class handles "skipping" the -configure and compile steps as well as sets things up to grab packages -from the appropriate area. In particular, this class sets ``noexec`` on -both the :ref:`ref-tasks-configure` -and :ref:`ref-tasks-compile` tasks, -sets ``FILES:${PN}`` to "/" so that it picks up all files, and sets up a -:ref:`ref-tasks-install` task, which -effectively copies all files from ``${S}`` to ``${D}``. The -:ref:`bin_package ` class works well when the files extracted into ``${S}`` -are already laid out in the way they should be laid out on the target. -For more information on these variables, see the -:term:`FILES`, -:term:`PN`, -:term:`S`, and -:term:`D` variables in the Yocto Project -Reference Manual's variable glossary. - -.. note:: - - - Using :term:`DEPENDS` is a good - idea even for components distributed in binary form, and is often - necessary for shared libraries. For a shared library, listing the - library dependencies in :term:`DEPENDS` makes sure that the libraries - are available in the staging sysroot when other recipes link - against the library, which might be necessary for successful - linking. - - - Using :term:`DEPENDS` also allows runtime dependencies between - packages to be added automatically. See the - ":ref:`overview-manual/concepts:automatically added runtime dependencies`" - section in the Yocto Project Overview and Concepts Manual for more - information. - -If you cannot use the :ref:`bin_package ` class, you need to be sure you are -doing the following: - -- Create a recipe where the - :ref:`ref-tasks-configure` and - :ref:`ref-tasks-compile` tasks do - nothing: It is usually sufficient to just not define these tasks in - the recipe, because the default implementations do nothing unless a - Makefile is found in - ``${``\ :term:`S`\ ``}``. - - If ``${S}`` might contain a Makefile, or if you inherit some class - that replaces ``do_configure`` and ``do_compile`` with custom - versions, then you can use the - ``[``\ :ref:`noexec `\ ``]`` - flag to turn the tasks into no-ops, as follows:: - - do_configure[noexec] = "1" - do_compile[noexec] = "1" - - Unlike - :ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:deleting a task`, - using the flag preserves the dependency chain from the - :ref:`ref-tasks-fetch`, - :ref:`ref-tasks-unpack`, and - :ref:`ref-tasks-patch` tasks to the - :ref:`ref-tasks-install` task. - -- Make sure your ``do_install`` task installs the binaries - appropriately. - -- Ensure that you set up :term:`FILES` - (usually - ``FILES:${``\ :term:`PN`\ ``}``) to - point to the files you have installed, which of course depends on - where you have installed them and whether those files are in - different locations than the defaults. - -Following Recipe Style Guidelines ---------------------------------- - -When writing recipes, it is good to conform to existing style -guidelines. The :oe_wiki:`OpenEmbedded Styleguide ` wiki page -provides rough guidelines for preferred recipe style. - -It is common for existing recipes to deviate a bit from this style. -However, aiming for at least a consistent style is a good idea. Some -practices, such as omitting spaces around ``=`` operators in assignments -or ordering recipe components in an erratic way, are widely seen as poor -style. - -Recipe Syntax -------------- - -Understanding recipe file syntax is important for writing recipes. The -following list overviews the basic items that make up a BitBake recipe -file. For more complete BitBake syntax descriptions, see the -":doc:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata`" -chapter of the BitBake User Manual. - -- *Variable Assignments and Manipulations:* Variable assignments allow - a value to be assigned to a variable. The assignment can be static - text or might include the contents of other variables. In addition to - the assignment, appending and prepending operations are also - supported. - - The following example shows some of the ways you can use variables in - recipes:: - - S = "${WORKDIR}/postfix-${PV}" - CFLAGS += "-DNO_ASM" - SRC_URI:append = " file://fixup.patch" - -- *Functions:* Functions provide a series of actions to be performed. - You usually use functions to override the default implementation of a - task function or to complement a default function (i.e. append or - prepend to an existing function). Standard functions use ``sh`` shell - syntax, although access to OpenEmbedded variables and internal - methods are also available. - - Here is an example function from the ``sed`` recipe:: - - do_install () { - autotools_do_install - install -d ${D}${base_bindir} - mv ${D}${bindir}/sed ${D}${base_bindir}/sed - rmdir ${D}${bindir}/ - } - - It is - also possible to implement new functions that are called between - existing tasks as long as the new functions are not replacing or - complementing the default functions. You can implement functions in - Python instead of shell. Both of these options are not seen in the - majority of recipes. - -- *Keywords:* BitBake recipes use only a few keywords. You use keywords - to include common functions (``inherit``), load parts of a recipe - from other files (``include`` and ``require``) and export variables - to the environment (``export``). - - The following example shows the use of some of these keywords:: - - export POSTCONF = "${STAGING_BINDIR}/postconf" - inherit autoconf - require otherfile.inc - -- *Comments (#):* Any lines that begin with the hash character (``#``) - are treated as comment lines and are ignored:: - - # This is a comment - -This next list summarizes the most important and most commonly used -parts of the recipe syntax. For more information on these parts of the -syntax, you can reference the -:doc:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata` chapter -in the BitBake User Manual. - -- *Line Continuation (\\):* Use the backward slash (``\``) character to - split a statement over multiple lines. Place the slash character at - the end of the line that is to be continued on the next line:: - - VAR = "A really long \ - line" - - .. note:: - - You cannot have any characters including spaces or tabs after the - slash character. - -- *Using Variables (${VARNAME}):* Use the ``${VARNAME}`` syntax to - access the contents of a variable:: - - SRC_URI = "${SOURCEFORGE_MIRROR}/libpng/zlib-${PV}.tar.gz" - - .. note:: - - It is important to understand that the value of a variable - expressed in this form does not get substituted automatically. The - expansion of these expressions happens on-demand later (e.g. - usually when a function that makes reference to the variable - executes). This behavior ensures that the values are most - appropriate for the context in which they are finally used. On the - rare occasion that you do need the variable expression to be - expanded immediately, you can use the - := - operator instead of - = - when you make the assignment, but this is not generally needed. - -- *Quote All Assignments ("value"):* Use double quotes around values in - all variable assignments (e.g. ``"value"``). Following is an example:: - - VAR1 = "${OTHERVAR}" - VAR2 = "The version is ${PV}" - -- *Conditional Assignment (?=):* Conditional assignment is used to - assign a value to a variable, but only when the variable is currently - unset. Use the question mark followed by the equal sign (``?=``) to - make a "soft" assignment used for conditional assignment. Typically, - "soft" assignments are used in the ``local.conf`` file for variables - that are allowed to come through from the external environment. - - Here is an example where ``VAR1`` is set to "New value" if it is - currently empty. However, if ``VAR1`` has already been set, it - remains unchanged:: - - VAR1 ?= "New value" - - In this next example, ``VAR1`` is left with the value "Original value":: - - VAR1 = "Original value" - VAR1 ?= "New value" - -- *Appending (+=):* Use the plus character followed by the equals sign - (``+=``) to append values to existing variables. - - .. note:: - - This operator adds a space between the existing content of the - variable and the new content. - - Here is an example:: - - SRC_URI += "file://fix-makefile.patch" - -- *Prepending (=+):* Use the equals sign followed by the plus character - (``=+``) to prepend values to existing variables. - - .. note:: - - This operator adds a space between the new content and the - existing content of the variable. - - Here is an example:: - - VAR =+ "Starts" - -- *Appending (:append):* Use the ``:append`` operator to append values - to existing variables. This operator does not add any additional - space. Also, the operator is applied after all the ``+=``, and ``=+`` - operators have been applied and after all ``=`` assignments have - occurred. - - The following example shows the space being explicitly added to the - start to ensure the appended value is not merged with the existing - value:: - - SRC_URI:append = " file://fix-makefile.patch" - - You can also use - the ``:append`` operator with overrides, which results in the actions - only being performed for the specified target or machine:: - - SRC_URI:append:sh4 = " file://fix-makefile.patch" - -- *Prepending (:prepend):* Use the ``:prepend`` operator to prepend - values to existing variables. This operator does not add any - additional space. Also, the operator is applied after all the ``+=``, - and ``=+`` operators have been applied and after all ``=`` - assignments have occurred. - - The following example shows the space being explicitly added to the - end to ensure the prepended value is not merged with the existing - value:: - - CFLAGS:prepend = "-I${S}/myincludes " - - You can also use the - ``:prepend`` operator with overrides, which results in the actions - only being performed for the specified target or machine:: - - CFLAGS:prepend:sh4 = "-I${S}/myincludes " - -- *Overrides:* You can use overrides to set a value conditionally, - typically based on how the recipe is being built. For example, to set - the :term:`KBRANCH` variable's - value to "standard/base" for any target - :term:`MACHINE`, except for - qemuarm where it should be set to "standard/arm-versatile-926ejs", - you would do the following:: - - KBRANCH = "standard/base" - KBRANCH:qemuarm = "standard/arm-versatile-926ejs" - - Overrides are also used to separate - alternate values of a variable in other situations. For example, when - setting variables such as - :term:`FILES` and - :term:`RDEPENDS` that are - specific to individual packages produced by a recipe, you should - always use an override that specifies the name of the package. - -- *Indentation:* Use spaces for indentation rather than tabs. For - shell functions, both currently work. However, it is a policy - decision of the Yocto Project to use tabs in shell functions. Realize - that some layers have a policy to use spaces for all indentation. - -- *Using Python for Complex Operations:* For more advanced processing, - it is possible to use Python code during variable assignments (e.g. - search and replacement on a variable). - - You indicate Python code using the ``${@python_code}`` syntax for the - variable assignment:: - - SRC_URI = "ftp://ftp.info-zip.org/pub/infozip/src/zip${@d.getVar('PV',1).replace('.', '')}.tgz - -- *Shell Function Syntax:* Write shell functions as if you were writing - a shell script when you describe a list of actions to take. You - should ensure that your script works with a generic ``sh`` and that - it does not require any ``bash`` or other shell-specific - functionality. The same considerations apply to various system - utilities (e.g. ``sed``, ``grep``, ``awk``, and so forth) that you - might wish to use. If in doubt, you should check with multiple - implementations - including those from BusyBox. - -Adding a New Machine -==================== - -Adding a new machine to the Yocto Project is a straightforward process. -This section describes how to add machines that are similar to those -that the Yocto Project already supports. - -.. note:: - - Although well within the capabilities of the Yocto Project, adding a - totally new architecture might require changes to ``gcc``/``glibc`` - and to the site information, which is beyond the scope of this - manual. - -For a complete example that shows how to add a new machine, see the -":ref:`bsp-guide/bsp:creating a new bsp layer using the \`\`bitbake-layers\`\` script`" -section in the Yocto Project Board Support Package (BSP) Developer's -Guide. - -Adding the Machine Configuration File -------------------------------------- - -To add a new machine, you need to add a new machine configuration file -to the layer's ``conf/machine`` directory. This configuration file -provides details about the device you are adding. - -The OpenEmbedded build system uses the root name of the machine -configuration file to reference the new machine. For example, given a -machine configuration file named ``crownbay.conf``, the build system -recognizes the machine as "crownbay". - -The most important variables you must set in your machine configuration -file or include from a lower-level configuration file are as follows: - -- :term:`TARGET_ARCH` (e.g. "arm") - -- ``PREFERRED_PROVIDER_virtual/kernel`` - -- :term:`MACHINE_FEATURES` (e.g. "apm screen wifi") - -You might also need these variables: - -- :term:`SERIAL_CONSOLES` (e.g. "115200;ttyS0 115200;ttyS1") - -- :term:`KERNEL_IMAGETYPE` (e.g. "zImage") - -- :term:`IMAGE_FSTYPES` (e.g. "tar.gz jffs2") - -You can find full details on these variables in the reference section. -You can leverage existing machine ``.conf`` files from -``meta-yocto-bsp/conf/machine/``. - -Adding a Kernel for the Machine -------------------------------- - -The OpenEmbedded build system needs to be able to build a kernel for the -machine. You need to either create a new kernel recipe for this machine, -or extend an existing kernel recipe. You can find several kernel recipe -examples in the Source Directory at ``meta/recipes-kernel/linux`` that -you can use as references. - -If you are creating a new kernel recipe, normal recipe-writing rules -apply for setting up a :term:`SRC_URI`. Thus, you need to specify any -necessary patches and set :term:`S` to point at the source code. You need to -create a ``do_configure`` task that configures the unpacked kernel with -a ``defconfig`` file. You can do this by using a ``make defconfig`` -command or, more commonly, by copying in a suitable ``defconfig`` file -and then running ``make oldconfig``. By making use of ``inherit kernel`` -and potentially some of the ``linux-*.inc`` files, most other -functionality is centralized and the defaults of the class normally work -well. - -If you are extending an existing kernel recipe, it is usually a matter -of adding a suitable ``defconfig`` file. The file needs to be added into -a location similar to ``defconfig`` files used for other machines in a -given kernel recipe. A possible way to do this is by listing the file in -the :term:`SRC_URI` and adding the machine to the expression in -:term:`COMPATIBLE_MACHINE`:: - - COMPATIBLE_MACHINE = '(qemux86|qemumips)' - -For more information on ``defconfig`` files, see the -":ref:`kernel-dev/common:changing the configuration`" -section in the Yocto Project Linux Kernel Development Manual. - -Adding a Formfactor Configuration File --------------------------------------- - -A formfactor configuration file provides information about the target -hardware for which the image is being built and information that the -build system cannot obtain from other sources such as the kernel. Some -examples of information contained in a formfactor configuration file -include framebuffer orientation, whether or not the system has a -keyboard, the positioning of the keyboard in relation to the screen, and -the screen resolution. - -The build system uses reasonable defaults in most cases. However, if -customization is necessary, you need to create a ``machconfig`` file in -the ``meta/recipes-bsp/formfactor/files`` directory. This directory -contains directories for specific machines such as ``qemuarm`` and -``qemux86``. For information about the settings available and the -defaults, see the ``meta/recipes-bsp/formfactor/files/config`` file -found in the same area. - -Following is an example for "qemuarm" machine:: - - HAVE_TOUCHSCREEN=1 - HAVE_KEYBOARD=1 - DISPLAY_CAN_ROTATE=0 - DISPLAY_ORIENTATION=0 - #DISPLAY_WIDTH_PIXELS=640 - #DISPLAY_HEIGHT_PIXELS=480 - #DISPLAY_BPP=16 - DISPLAY_DPI=150 - DISPLAY_SUBPIXEL_ORDER=vrgb - -Upgrading Recipes -================= - -Over time, upstream developers publish new versions for software built -by layer recipes. It is recommended to keep recipes up-to-date with -upstream version releases. - -While there are several methods to upgrade a recipe, you might -consider checking on the upgrade status of a recipe first. You can do so -using the ``devtool check-upgrade-status`` command. See the -":ref:`devtool-checking-on-the-upgrade-status-of-a-recipe`" -section in the Yocto Project Reference Manual for more information. - -The remainder of this section describes three ways you can upgrade a -recipe. You can use the Automated Upgrade Helper (AUH) to set up -automatic version upgrades. Alternatively, you can use -``devtool upgrade`` to set up semi-automatic version upgrades. Finally, -you can manually upgrade a recipe by editing the recipe itself. - -Using the Auto Upgrade Helper (AUH) ------------------------------------ - -The AUH utility works in conjunction with the OpenEmbedded build system -in order to automatically generate upgrades for recipes based on new -versions being published upstream. Use AUH when you want to create a -service that performs the upgrades automatically and optionally sends -you an email with the results. - -AUH allows you to update several recipes with a single use. You can also -optionally perform build and integration tests using images with the -results saved to your hard drive and emails of results optionally sent -to recipe maintainers. Finally, AUH creates Git commits with appropriate -commit messages in the layer's tree for the changes made to recipes. - -.. note:: - - In some conditions, you should not use AUH to upgrade recipes - and should instead use either ``devtool upgrade`` or upgrade your - recipes manually: - - - When AUH cannot complete the upgrade sequence. This situation - usually results because custom patches carried by the recipe - cannot be automatically rebased to the new version. In this case, - ``devtool upgrade`` allows you to manually resolve conflicts. - - - When for any reason you want fuller control over the upgrade - process. For example, when you want special arrangements for - testing. - -The following steps describe how to set up the AUH utility: - -1. *Be Sure the Development Host is Set Up:* You need to be sure that - your development host is set up to use the Yocto Project. For - information on how to set up your host, see the - ":ref:`dev-manual/start:Preparing the Build Host`" section. - -2. *Make Sure Git is Configured:* The AUH utility requires Git to be - configured because AUH uses Git to save upgrades. Thus, you must have - Git user and email configured. The following command shows your - configurations:: - - $ git config --list - - If you do not have the user and - email configured, you can use the following commands to do so:: - - $ git config --global user.name some_name - $ git config --global user.email username@domain.com - -3. *Clone the AUH Repository:* To use AUH, you must clone the repository - onto your development host. The following command uses Git to create - a local copy of the repository on your system:: - - $ git clone git://git.yoctoproject.org/auto-upgrade-helper - Cloning into 'auto-upgrade-helper'... remote: Counting objects: 768, done. - remote: Compressing objects: 100% (300/300), done. - remote: Total 768 (delta 499), reused 703 (delta 434) - Receiving objects: 100% (768/768), 191.47 KiB | 98.00 KiB/s, done. - Resolving deltas: 100% (499/499), done. - Checking connectivity... done. - - AUH is not part of the :term:`OpenEmbedded-Core (OE-Core)` or - :term:`Poky` repositories. - -4. *Create a Dedicated Build Directory:* Run the - :ref:`structure-core-script` - script to create a fresh build directory that you use exclusively for - running the AUH utility:: - - $ cd poky - $ source oe-init-build-env your_AUH_build_directory - - Re-using an existing build directory and its configurations is not - recommended as existing settings could cause AUH to fail or behave - undesirably. - -5. *Make Configurations in Your Local Configuration File:* Several - settings are needed in the ``local.conf`` file in the build - directory you just created for AUH. Make these following - configurations: - - - If you want to enable :ref:`Build - History `, - which is optional, you need the following lines in the - ``conf/local.conf`` file:: - - INHERIT =+ "buildhistory" - BUILDHISTORY_COMMIT = "1" - - With this configuration and a successful - upgrade, a build history "diff" file appears in the - ``upgrade-helper/work/recipe/buildhistory-diff.txt`` file found in - your build directory. - - - If you want to enable testing through the - :ref:`testimage ` - class, which is optional, you need to have the following set in - your ``conf/local.conf`` file:: - - INHERIT += "testimage" - - .. note:: - - If your distro does not enable by default ptest, which Poky - does, you need the following in your ``local.conf`` file:: - - DISTRO_FEATURES:append = " ptest" - - -6. *Optionally Start a vncserver:* If you are running in a server - without an X11 session, you need to start a vncserver:: - - $ vncserver :1 - $ export DISPLAY=:1 - -7. *Create and Edit an AUH Configuration File:* You need to have the - ``upgrade-helper/upgrade-helper.conf`` configuration file in your - build directory. You can find a sample configuration file in the - :yocto_git:`AUH source repository `. - - Read through the sample file and make configurations as needed. For - example, if you enabled build history in your ``local.conf`` as - described earlier, you must enable it in ``upgrade-helper.conf``. - - Also, if you are using the default ``maintainers.inc`` file supplied - with Poky and located in ``meta-yocto`` and you do not set a - "maintainers_whitelist" or "global_maintainer_override" in the - ``upgrade-helper.conf`` configuration, and you specify "-e all" on - the AUH command-line, the utility automatically sends out emails to - all the default maintainers. Please avoid this. - -This next set of examples describes how to use the AUH: - -- *Upgrading a Specific Recipe:* To upgrade a specific recipe, use the - following form:: - - $ upgrade-helper.py recipe_name - - For example, this command upgrades the ``xmodmap`` recipe:: - - $ upgrade-helper.py xmodmap - -- *Upgrading a Specific Recipe to a Particular Version:* To upgrade a - specific recipe to a particular version, use the following form:: - - $ upgrade-helper.py recipe_name -t version - - For example, this command upgrades the ``xmodmap`` recipe to version 1.2.3:: - - $ upgrade-helper.py xmodmap -t 1.2.3 - -- *Upgrading all Recipes to the Latest Versions and Suppressing Email - Notifications:* To upgrade all recipes to their most recent versions - and suppress the email notifications, use the following command:: - - $ upgrade-helper.py all - -- *Upgrading all Recipes to the Latest Versions and Send Email - Notifications:* To upgrade all recipes to their most recent versions - and send email messages to maintainers for each attempted recipe as - well as a status email, use the following command:: - - $ upgrade-helper.py -e all - -Once you have run the AUH utility, you can find the results in the AUH -build directory:: - - ${BUILDDIR}/upgrade-helper/timestamp - -The AUH utility -also creates recipe update commits from successful upgrade attempts in -the layer tree. - -You can easily set up to run the AUH utility on a regular basis by using -a cron job. See the -:yocto_git:`weeklyjob.sh ` -file distributed with the utility for an example. - -Using ``devtool upgrade`` -------------------------- - -As mentioned earlier, an alternative method for upgrading recipes to -newer versions is to use -:doc:`devtool upgrade `. -You can read about ``devtool upgrade`` in general in the -":ref:`sdk-manual/extensible:use \`\`devtool upgrade\`\` to create a version of the recipe that supports a newer version of the software`" -section in the Yocto Project Application Development and the Extensible -Software Development Kit (eSDK) Manual. - -To see all the command-line options available with ``devtool upgrade``, -use the following help command:: - - $ devtool upgrade -h - -If you want to find out what version a recipe is currently at upstream -without any attempt to upgrade your local version of the recipe, you can -use the following command:: - - $ devtool latest-version recipe_name - -As mentioned in the previous section describing AUH, ``devtool upgrade`` -works in a less-automated manner than AUH. Specifically, -``devtool upgrade`` only works on a single recipe that you name on the -command line, cannot perform build and integration testing using images, -and does not automatically generate commits for changes in the source -tree. Despite all these "limitations", ``devtool upgrade`` updates the -recipe file to the new upstream version and attempts to rebase custom -patches contained by the recipe as needed. - -.. note:: - - AUH uses much of ``devtool upgrade`` behind the scenes making AUH somewhat - of a "wrapper" application for ``devtool upgrade``. - -A typical scenario involves having used Git to clone an upstream -repository that you use during build operations. Because you have built the -recipe in the past, the layer is likely added to your -configuration already. If for some reason, the layer is not added, you -could add it easily using the -":ref:`bitbake-layers `" -script. For example, suppose you use the ``nano.bb`` recipe from the -``meta-oe`` layer in the ``meta-openembedded`` repository. For this -example, assume that the layer has been cloned into following area:: - - /home/scottrif/meta-openembedded - -The following command from your -:term:`Build Directory` adds the layer to -your build configuration (i.e. ``${BUILDDIR}/conf/bblayers.conf``):: - - $ bitbake-layers add-layer /home/scottrif/meta-openembedded/meta-oe - NOTE: Starting bitbake server... - Parsing recipes: 100% |##########################################| Time: 0:00:55 - Parsing of 1431 .bb files complete (0 cached, 1431 parsed). 2040 targets, 56 skipped, 0 masked, 0 errors. - Removing 12 recipes from the x86_64 sysroot: 100% |##############| Time: 0:00:00 - Removing 1 recipes from the x86_64_i586 sysroot: 100% |##########| Time: 0:00:00 - Removing 5 recipes from the i586 sysroot: 100% |#################| Time: 0:00:00 - Removing 5 recipes from the qemux86 sysroot: 100% |##############| Time: 0:00:00 - -For this example, assume that the ``nano.bb`` recipe that -is upstream has a 2.9.3 version number. However, the version in the -local repository is 2.7.4. The following command from your build -directory automatically upgrades the recipe for you: - -.. note:: - - Using the ``-V`` option is not necessary. Omitting the version number causes - ``devtool upgrade`` to upgrade the recipe to the most recent version. - -:: - - $ devtool upgrade nano -V 2.9.3 - NOTE: Starting bitbake server... - NOTE: Creating workspace layer in /home/scottrif/poky/build/workspace - Parsing recipes: 100% |##########################################| Time: 0:00:46 - Parsing of 1431 .bb files complete (0 cached, 1431 parsed). 2040 targets, 56 skipped, 0 masked, 0 errors. - NOTE: Extracting current version source... - NOTE: Resolving any missing task queue dependencies - . - . - . - NOTE: Executing SetScene Tasks - NOTE: Executing RunQueue Tasks - NOTE: Tasks Summary: Attempted 74 tasks of which 72 didn't need to be rerun and all succeeded. - Adding changed files: 100% |#####################################| Time: 0:00:00 - NOTE: Upgraded source extracted to /home/scottrif/poky/build/workspace/sources/nano - NOTE: New recipe is /home/scottrif/poky/build/workspace/recipes/nano/nano_2.9.3.bb - -Continuing with this example, you can use ``devtool build`` to build the -newly upgraded recipe:: - - $ devtool build nano - NOTE: Starting bitbake server... - Loading cache: 100% |################################################################################################| Time: 0:00:01 - Loaded 2040 entries from dependency cache. - Parsing recipes: 100% |##############################################################################################| Time: 0:00:00 - Parsing of 1432 .bb files complete (1431 cached, 1 parsed). 2041 targets, 56 skipped, 0 masked, 0 errors. - NOTE: Resolving any missing task queue dependencies - . - . - . - NOTE: Executing SetScene Tasks - NOTE: Executing RunQueue Tasks - NOTE: nano: compiling from external source tree /home/scottrif/poky/build/workspace/sources/nano - NOTE: Tasks Summary: Attempted 520 tasks of which 304 didn't need to be rerun and all succeeded. - -Within the ``devtool upgrade`` workflow, you can -deploy and test your rebuilt software. For this example, -however, running ``devtool finish`` cleans up the workspace once the -source in your workspace is clean. This usually means using Git to stage -and submit commits for the changes generated by the upgrade process. - -Once the tree is clean, you can clean things up in this example with the -following command from the ``${BUILDDIR}/workspace/sources/nano`` -directory:: - - $ devtool finish nano meta-oe - NOTE: Starting bitbake server... - Loading cache: 100% |################################################################################################| Time: 0:00:00 - Loaded 2040 entries from dependency cache. - Parsing recipes: 100% |##############################################################################################| Time: 0:00:01 - Parsing of 1432 .bb files complete (1431 cached, 1 parsed). 2041 targets, 56 skipped, 0 masked, 0 errors. - NOTE: Adding new patch 0001-nano.bb-Stuff-I-changed-when-upgrading-nano.bb.patch - NOTE: Updating recipe nano_2.9.3.bb - NOTE: Removing file /home/scottrif/meta-openembedded/meta-oe/recipes-support/nano/nano_2.7.4.bb - NOTE: Moving recipe file to /home/scottrif/meta-openembedded/meta-oe/recipes-support/nano - NOTE: Leaving source tree /home/scottrif/poky/build/workspace/sources/nano as-is; if you no longer need it then please delete it manually - - -Using the ``devtool finish`` command cleans up the workspace and creates a patch -file based on your commits. The tool puts all patch files back into the -source directory in a sub-directory named ``nano`` in this case. - -Manually Upgrading a Recipe ---------------------------- - -If for some reason you choose not to upgrade recipes using -:ref:`dev-manual/common-tasks:Using the Auto Upgrade Helper (AUH)` or -by :ref:`dev-manual/common-tasks:Using \`\`devtool upgrade\`\``, -you can manually edit the recipe files to upgrade the versions. - -.. note:: - - Manually updating multiple recipes scales poorly and involves many - steps. The recommendation to upgrade recipe versions is through AUH - or ``devtool upgrade``, both of which automate some steps and provide - guidance for others needed for the manual process. - -To manually upgrade recipe versions, follow these general steps: - -1. *Change the Version:* Rename the recipe such that the version (i.e. - the :term:`PV` part of the recipe name) - changes appropriately. If the version is not part of the recipe name, - change the value as it is set for :term:`PV` within the recipe itself. - -2. *Update* :term:`SRCREV` *if Needed*: If the source code your recipe builds - is fetched from Git or some other version control system, update - :term:`SRCREV` to point to the - commit hash that matches the new version. - -3. *Build the Software:* Try to build the recipe using BitBake. Typical - build failures include the following: - - - License statements were updated for the new version. For this - case, you need to review any changes to the license and update the - values of :term:`LICENSE` and - :term:`LIC_FILES_CHKSUM` - as needed. - - .. note:: - - License changes are often inconsequential. For example, the - license text's copyright year might have changed. - - - Custom patches carried by the older version of the recipe might - fail to apply to the new version. For these cases, you need to - review the failures. Patches might not be necessary for the new - version of the software if the upgraded version has fixed those - issues. If a patch is necessary and failing, you need to rebase it - into the new version. - -4. *Optionally Attempt to Build for Several Architectures:* Once you - successfully build the new software for a given architecture, you - could test the build for other architectures by changing the - :term:`MACHINE` variable and - rebuilding the software. This optional step is especially important - if the recipe is to be released publicly. - -5. *Check the Upstream Change Log or Release Notes:* Checking both these - reveals if there are new features that could break - backwards-compatibility. If so, you need to take steps to mitigate or - eliminate that situation. - -6. *Optionally Create a Bootable Image and Test:* If you want, you can - test the new software by booting it onto actual hardware. - -7. *Create a Commit with the Change in the Layer Repository:* After all - builds work and any testing is successful, you can create commits for - any changes in the layer holding your upgraded recipe. - -Finding Temporary Source Code -============================= - -You might find it helpful during development to modify the temporary -source code used by recipes to build packages. For example, suppose you -are developing a patch and you need to experiment a bit to figure out -your solution. After you have initially built the package, you can -iteratively tweak the source code, which is located in the -:term:`Build Directory`, and then you can -force a re-compile and quickly test your altered code. Once you settle -on a solution, you can then preserve your changes in the form of -patches. - -During a build, the unpacked temporary source code used by recipes to -build packages is available in the Build Directory as defined by the -:term:`S` variable. Below is the default -value for the :term:`S` variable as defined in the -``meta/conf/bitbake.conf`` configuration file in the -:term:`Source Directory`:: - - S = "${WORKDIR}/${BP}" - -You should be aware that many recipes override the -:term:`S` variable. For example, recipes that fetch their source from Git -usually set :term:`S` to ``${WORKDIR}/git``. - -.. note:: - - The :term:`BP` represents the base recipe name, which consists of the name - and version:: - - BP = "${BPN}-${PV}" - - -The path to the work directory for the recipe -(:term:`WORKDIR`) is defined as -follows:: - - ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR} - -The actual directory depends on several things: - -- :term:`TMPDIR`: The top-level build - output directory. - -- :term:`MULTIMACH_TARGET_SYS`: - The target system identifier. - -- :term:`PN`: The recipe name. - -- :term:`EXTENDPE`: The epoch - (if - :term:`PE` is not specified, which is - usually the case for most recipes, then :term:`EXTENDPE` is blank). - -- :term:`PV`: The recipe version. - -- :term:`PR`: The recipe revision. - -As an example, assume a Source Directory top-level folder named -``poky``, a default Build Directory at ``poky/build``, and a -``qemux86-poky-linux`` machine target system. Furthermore, suppose your -recipe is named ``foo_1.3.0.bb``. In this case, the work directory the -build system uses to build the package would be as follows:: - - poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0 - -Using Quilt in Your Workflow -============================ - -`Quilt `__ is a powerful tool -that allows you to capture source code changes without having a clean -source tree. This section outlines the typical workflow you can use to -modify source code, test changes, and then preserve the changes in the -form of a patch all using Quilt. - -.. note:: - - With regard to preserving changes to source files, if you clean a - recipe or have ``rm_work`` enabled, the - :ref:`devtool workflow ` - as described in the Yocto Project Application Development and the - Extensible Software Development Kit (eSDK) manual is a safer - development flow than the flow that uses Quilt. - -Follow these general steps: - -1. *Find the Source Code:* Temporary source code used by the - OpenEmbedded build system is kept in the - :term:`Build Directory`. See the - ":ref:`dev-manual/common-tasks:finding temporary source code`" section to - learn how to locate the directory that has the temporary source code for a - particular package. - -2. *Change Your Working Directory:* You need to be in the directory that - has the temporary source code. That directory is defined by the - :term:`S` variable. - -3. *Create a New Patch:* Before modifying source code, you need to - create a new patch. To create a new patch file, use ``quilt new`` as - below:: - - $ quilt new my_changes.patch - -4. *Notify Quilt and Add Files:* After creating the patch, you need to - notify Quilt about the files you plan to edit. You notify Quilt by - adding the files to the patch you just created:: - - $ quilt add file1.c file2.c file3.c - -5. *Edit the Files:* Make your changes in the source code to the files - you added to the patch. - -6. *Test Your Changes:* Once you have modified the source code, the - easiest way to test your changes is by calling the ``do_compile`` - task as shown in the following example:: - - $ bitbake -c compile -f package - - The ``-f`` or ``--force`` option forces the specified task to - execute. If you find problems with your code, you can just keep - editing and re-testing iteratively until things work as expected. - - .. note:: - - All the modifications you make to the temporary source code disappear - once you run the ``do_clean`` or ``do_cleanall`` tasks using BitBake - (i.e. ``bitbake -c clean package`` and ``bitbake -c cleanall package``). - Modifications will also disappear if you use the ``rm_work`` feature as - described in the - ":ref:`dev-manual/common-tasks:conserving disk space during builds`" - section. - -7. *Generate the Patch:* Once your changes work as expected, you need to - use Quilt to generate the final patch that contains all your - modifications. - :: - - $ quilt refresh - - At this point, the - ``my_changes.patch`` file has all your edits made to the ``file1.c``, - ``file2.c``, and ``file3.c`` files. - - You can find the resulting patch file in the ``patches/`` - subdirectory of the source (:term:`S`) directory. - -8. *Copy the Patch File:* For simplicity, copy the patch file into a - directory named ``files``, which you can create in the same directory - that holds the recipe (``.bb``) file or the append (``.bbappend``) - file. Placing the patch here guarantees that the OpenEmbedded build - system will find the patch. Next, add the patch into the :term:`SRC_URI` - of the recipe. Here is an example:: - - SRC_URI += "file://my_changes.patch" - -Using a Development Shell -========================= - -When debugging certain commands or even when just editing packages, -``devshell`` can be a useful tool. When you invoke ``devshell``, all -tasks up to and including -:ref:`ref-tasks-patch` are run for the -specified target. Then, a new terminal is opened and you are placed in -``${``\ :term:`S`\ ``}``, the source -directory. In the new terminal, all the OpenEmbedded build-related -environment variables are still defined so you can use commands such as -``configure`` and ``make``. The commands execute just as if the -OpenEmbedded build system were executing them. Consequently, working -this way can be helpful when debugging a build or preparing software to -be used with the OpenEmbedded build system. - -Following is an example that uses ``devshell`` on a target named -``matchbox-desktop``:: - - $ bitbake matchbox-desktop -c devshell - -This command spawns a terminal with a shell prompt within the -OpenEmbedded build environment. The -:term:`OE_TERMINAL` variable -controls what type of shell is opened. - -For spawned terminals, the following occurs: - -- The ``PATH`` variable includes the cross-toolchain. - -- The ``pkgconfig`` variables find the correct ``.pc`` files. - -- The ``configure`` command finds the Yocto Project site files as well - as any other necessary files. - -Within this environment, you can run configure or compile commands as if -they were being run by the OpenEmbedded build system itself. As noted -earlier, the working directory also automatically changes to the Source -Directory (:term:`S`). - -To manually run a specific task using ``devshell``, run the -corresponding ``run.*`` script in the -``${``\ :term:`WORKDIR`\ ``}/temp`` -directory (e.g., ``run.do_configure.``\ `pid`). If a task's script does -not exist, which would be the case if the task was skipped by way of the -sstate cache, you can create the task by first running it outside of the -``devshell``:: - - $ bitbake -c task - -.. note:: - - - Execution of a task's ``run.*`` script and BitBake's execution of - a task are identical. In other words, running the script re-runs - the task just as it would be run using the ``bitbake -c`` command. - - - Any ``run.*`` file that does not have a ``.pid`` extension is a - symbolic link (symlink) to the most recent version of that file. - -Remember, that the ``devshell`` is a mechanism that allows you to get -into the BitBake task execution environment. And as such, all commands -must be called just as BitBake would call them. That means you need to -provide the appropriate options for cross-compilation and so forth as -applicable. - -When you are finished using ``devshell``, exit the shell or close the -terminal window. - -.. note:: - - - It is worth remembering that when using ``devshell`` you need to - use the full compiler name such as ``arm-poky-linux-gnueabi-gcc`` - instead of just using ``gcc``. The same applies to other - applications such as ``binutils``, ``libtool`` and so forth. - BitBake sets up environment variables such as :term:`CC` to assist - applications, such as ``make`` to find the correct tools. - - - It is also worth noting that ``devshell`` still works over X11 - forwarding and similar situations. - -Using a Python Development Shell -================================ - -Similar to working within a development shell as described in the -previous section, you can also spawn and work within an interactive -Python development shell. When debugging certain commands or even when -just editing packages, ``pydevshell`` can be a useful tool. When you -invoke the ``pydevshell`` task, all tasks up to and including -:ref:`ref-tasks-patch` are run for the -specified target. Then a new terminal is opened. Additionally, key -Python objects and code are available in the same way they are to -BitBake tasks, in particular, the data store 'd'. So, commands such as -the following are useful when exploring the data store and running -functions:: - - pydevshell> d.getVar("STAGING_DIR") - '/media/build1/poky/build/tmp/sysroots' - pydevshell> d.getVar("STAGING_DIR", False) - '${TMPDIR}/sysroots' - pydevshell> d.setVar("FOO", "bar") - pydevshell> d.getVar("FOO") - 'bar' - pydevshell> d.delVar("FOO") - pydevshell> d.getVar("FOO") - pydevshell> bb.build.exec_func("do_unpack", d) - pydevshell> - -The commands execute just as if the OpenEmbedded build -system were executing them. Consequently, working this way can be -helpful when debugging a build or preparing software to be used with the -OpenEmbedded build system. - -Following is an example that uses ``pydevshell`` on a target named -``matchbox-desktop``:: - - $ bitbake matchbox-desktop -c pydevshell - -This command spawns a terminal and places you in an interactive Python -interpreter within the OpenEmbedded build environment. The -:term:`OE_TERMINAL` variable -controls what type of shell is opened. - -When you are finished using ``pydevshell``, you can exit the shell -either by using Ctrl+d or closing the terminal window. - -Building -======== - -This section describes various build procedures, such as the steps -needed for a simple build, building a target for multiple configurations, -generating an image for more than one machine, and so forth. - -Building a Simple Image ------------------------ - -In the development environment, you need to build an image whenever you -change hardware support, add or change system libraries, or add or -change services that have dependencies. There are several methods that allow -you to build an image within the Yocto Project. This section presents -the basic steps you need to build a simple image using BitBake from a -build host running Linux. - -.. note:: - - - For information on how to build an image using - :term:`Toaster`, see the - :doc:`/toaster-manual/index`. - - - For information on how to use ``devtool`` to build images, see the - ":ref:`sdk-manual/extensible:using \`\`devtool\`\` in your sdk workflow`" - section in the Yocto Project Application Development and the - Extensible Software Development Kit (eSDK) manual. - - - For a quick example on how to build an image using the - OpenEmbedded build system, see the - :doc:`/brief-yoctoprojectqs/index` document. - -The build process creates an entire Linux distribution from source and -places it in your :term:`Build Directory` under -``tmp/deploy/images``. For detailed information on the build process -using BitBake, see the ":ref:`overview-manual/concepts:images`" section in the -Yocto Project Overview and Concepts Manual. - -The following figure and list overviews the build process: - -.. image:: figures/bitbake-build-flow.png - :align: center - -1. *Set up Your Host Development System to Support Development Using the - Yocto Project*: See the ":doc:`start`" section for options on how to get a - build host ready to use the Yocto Project. - -2. *Initialize the Build Environment:* Initialize the build environment - by sourcing the build environment script (i.e. - :ref:`structure-core-script`):: - - $ source oe-init-build-env [build_dir] - - When you use the initialization script, the OpenEmbedded build system - uses ``build`` as the default :term:`Build Directory` in your current work - directory. You can use a `build_dir` argument with the script to - specify a different build directory. - - .. note:: - - A common practice is to use a different Build Directory for - different targets; for example, ``~/build/x86`` for a ``qemux86`` - target, and ``~/build/arm`` for a ``qemuarm`` target. In any - event, it's typically cleaner to locate the build directory - somewhere outside of your source directory. - -3. *Make Sure Your* ``local.conf`` *File is Correct*: Ensure the - ``conf/local.conf`` configuration file, which is found in the Build - Directory, is set up how you want it. This file defines many aspects - of the build environment including the target machine architecture - through the :term:`MACHINE` variable, the packaging format used during - the build - (:term:`PACKAGE_CLASSES`), - and a centralized tarball download directory through the - :term:`DL_DIR` variable. - -4. *Build the Image:* Build the image using the ``bitbake`` command:: - - $ bitbake target - - .. note:: - - For information on BitBake, see the :doc:`bitbake:index`. - - The target is the name of the recipe you want to build. Common - targets are the images in ``meta/recipes-core/images``, - ``meta/recipes-sato/images``, and so forth all found in the - :term:`Source Directory`. Alternatively, the target - can be the name of a recipe for a specific piece of software such as - BusyBox. For more details about the images the OpenEmbedded build - system supports, see the - ":ref:`ref-manual/images:Images`" chapter in the Yocto - Project Reference Manual. - - As an example, the following command builds the - ``core-image-minimal`` image:: - - $ bitbake core-image-minimal - - Once an - image has been built, it often needs to be installed. The images and - kernels built by the OpenEmbedded build system are placed in the - Build Directory in ``tmp/deploy/images``. For information on how to - run pre-built images such as ``qemux86`` and ``qemuarm``, see the - :doc:`/sdk-manual/index` manual. For - information about how to install these images, see the documentation - for your particular board or machine. - -Building Images for Multiple Targets Using Multiple Configurations ------------------------------------------------------------------- - -You can use a single ``bitbake`` command to build multiple images or -packages for different targets where each image or package requires a -different configuration (multiple configuration builds). The builds, in -this scenario, are sometimes referred to as "multiconfigs", and this -section uses that term throughout. - -This section describes how to set up for multiple configuration builds -and how to account for cross-build dependencies between the -multiconfigs. - -Setting Up and Running a Multiple Configuration Build -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -To accomplish a multiple configuration build, you must define each -target's configuration separately using a parallel configuration file in -the :term:`Build Directory`, and you -must follow a required file hierarchy. Additionally, you must enable the -multiple configuration builds in your ``local.conf`` file. - -Follow these steps to set up and execute multiple configuration builds: - -- *Create Separate Configuration Files*: You need to create a single - configuration file for each build target (each multiconfig). - Minimally, each configuration file must define the machine and the - temporary directory BitBake uses for the build. Suggested practice - dictates that you do not overlap the temporary directories used - during the builds. However, it is possible that you can share the - temporary directory - (:term:`TMPDIR`). For example, - consider a scenario with two different multiconfigs for the same - :term:`MACHINE`: "qemux86" built - for two distributions such as "poky" and "poky-lsb". In this case, - you might want to use the same :term:`TMPDIR`. - - Here is an example showing the minimal statements needed in a - configuration file for a "qemux86" target whose temporary build - directory is ``tmpmultix86``:: - - MACHINE = "qemux86" - TMPDIR = "${TOPDIR}/tmpmultix86" - - The location for these multiconfig configuration files is specific. - They must reside in the current build directory in a sub-directory of - ``conf`` named ``multiconfig``. Following is an example that defines - two configuration files for the "x86" and "arm" multiconfigs: - - .. image:: figures/multiconfig_files.png - :align: center - - The reason for this required file hierarchy is because the :term:`BBPATH` - variable is not constructed until the layers are parsed. - Consequently, using the configuration file as a pre-configuration - file is not possible unless it is located in the current working - directory. - -- *Add the BitBake Multi-configuration Variable to the Local - Configuration File*: Use the - :term:`BBMULTICONFIG` - variable in your ``conf/local.conf`` configuration file to specify - each multiconfig. Continuing with the example from the previous - figure, the :term:`BBMULTICONFIG` variable needs to enable two - multiconfigs: "x86" and "arm" by specifying each configuration file:: - - BBMULTICONFIG = "x86 arm" - - .. note:: - - A "default" configuration already exists by definition. This - configuration is named: "" (i.e. empty string) and is defined by - the variables coming from your ``local.conf`` - file. Consequently, the previous example actually adds two - additional configurations to your build: "arm" and "x86" along - with "". - -- *Launch BitBake*: Use the following BitBake command form to launch - the multiple configuration build:: - - $ bitbake [mc:multiconfigname:]target [[[mc:multiconfigname:]target] ... ] - - For the example in this section, the following command applies:: - - $ bitbake mc:x86:core-image-minimal mc:arm:core-image-sato mc::core-image-base - - The previous BitBake command builds a ``core-image-minimal`` image - that is configured through the ``x86.conf`` configuration file, a - ``core-image-sato`` image that is configured through the ``arm.conf`` - configuration file and a ``core-image-base`` that is configured - through your ``local.conf`` configuration file. - -.. note:: - - Support for multiple configuration builds in the Yocto Project &DISTRO; - (&DISTRO_NAME;) Release does not include Shared State (sstate) - optimizations. Consequently, if a build uses the same object twice - in, for example, two different :term:`TMPDIR` - directories, the build either loads from an existing sstate cache for - that build at the start or builds the object fresh. - -Enabling Multiple Configuration Build Dependencies -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Sometimes dependencies can exist between targets (multiconfigs) in a -multiple configuration build. For example, suppose that in order to -build a ``core-image-sato`` image for an "x86" multiconfig, the root -filesystem of an "arm" multiconfig must exist. This dependency is -essentially that the -:ref:`ref-tasks-image` task in the -``core-image-sato`` recipe depends on the completion of the -:ref:`ref-tasks-rootfs` task of the -``core-image-minimal`` recipe. - -To enable dependencies in a multiple configuration build, you must -declare the dependencies in the recipe using the following statement -form:: - - task_or_package[mcdepends] = "mc:from_multiconfig:to_multiconfig:recipe_name:task_on_which_to_depend" - -To better show how to use this statement, consider the example scenario -from the first paragraph of this section. The following statement needs -to be added to the recipe that builds the ``core-image-sato`` image:: - - do_image[mcdepends] = "mc:x86:arm:core-image-minimal:do_rootfs" - -In this example, the `from_multiconfig` is "x86". The `to_multiconfig` is "arm". The -task on which the ``do_image`` task in the recipe depends is the -``do_rootfs`` task from the ``core-image-minimal`` recipe associated -with the "arm" multiconfig. - -Once you set up this dependency, you can build the "x86" multiconfig -using a BitBake command as follows:: - - $ bitbake mc:x86:core-image-sato - -This command executes all the tasks needed to create the -``core-image-sato`` image for the "x86" multiconfig. Because of the -dependency, BitBake also executes through the ``do_rootfs`` task for the -"arm" multiconfig build. - -Having a recipe depend on the root filesystem of another build might not -seem that useful. Consider this change to the statement in the -``core-image-sato`` recipe:: - - do_image[mcdepends] = "mc:x86:arm:core-image-minimal:do_image" - -In this case, BitBake must -create the ``core-image-minimal`` image for the "arm" build since the -"x86" build depends on it. - -Because "x86" and "arm" are enabled for multiple configuration builds -and have separate configuration files, BitBake places the artifacts for -each build in the respective temporary build directories (i.e. -:term:`TMPDIR`). - -Building an Initial RAM Filesystem (initramfs) Image ----------------------------------------------------- - -An initial RAM filesystem (initramfs) image provides a temporary root -filesystem used for early system initialization (e.g. loading of modules -needed to locate and mount the "real" root filesystem). - -.. note:: - - The initramfs image is the successor of initial RAM disk (initrd). It - is a "copy in and out" (cpio) archive of the initial filesystem that - gets loaded into memory during the Linux startup process. Because - Linux uses the contents of the archive during initialization, the - initramfs image needs to contain all of the device drivers and tools - needed to mount the final root filesystem. - -Follow these steps to create an initramfs image: - -1. *Create the initramfs Image Recipe:* You can reference the - ``core-image-minimal-initramfs.bb`` recipe found in the - ``meta/recipes-core`` directory of the :term:`Source Directory` - as an example - from which to work. - -2. *Decide if You Need to Bundle the initramfs Image Into the Kernel - Image:* If you want the initramfs image that is built to be bundled - in with the kernel image, set the - :term:`INITRAMFS_IMAGE_BUNDLE` - variable to "1" in your ``local.conf`` configuration file and set the - :term:`INITRAMFS_IMAGE` - variable in the recipe that builds the kernel image. - - .. note:: - - It is recommended that you bundle the initramfs image with the - kernel image to avoid circular dependencies between the kernel - recipe and the initramfs recipe should the initramfs image include - kernel modules. - - Setting the :term:`INITRAMFS_IMAGE_BUNDLE` flag causes the initramfs - image to be unpacked into the ``${B}/usr/`` directory. The unpacked - initramfs image is then passed to the kernel's ``Makefile`` using the - :term:`CONFIG_INITRAMFS_SOURCE` - variable, allowing the initramfs image to be built into the kernel - normally. - - .. note:: - - Bundling the initramfs with the kernel conflates the code in the initramfs - with the GPLv2 licensed Linux kernel binary. Thus only GPLv2 compatible - software may be part of a bundled initramfs. - - .. note:: - - If you choose to not bundle the initramfs image with the kernel - image, you are essentially using an - `Initial RAM Disk (initrd) `__. - Creating an initrd is handled primarily through the :term:`INITRD_IMAGE`, - ``INITRD_LIVE``, and ``INITRD_IMAGE_LIVE`` variables. For more - information, see the :ref:`ref-classes-image-live` file. - -3. *Optionally Add Items to the initramfs Image Through the initramfs - Image Recipe:* If you add items to the initramfs image by way of its - recipe, you should use - :term:`PACKAGE_INSTALL` - rather than - :term:`IMAGE_INSTALL`. - :term:`PACKAGE_INSTALL` gives more direct control of what is added to the - image as compared to the defaults you might not necessarily want that - are set by the :ref:`image ` - or :ref:`core-image ` - classes. - -4. *Build the Kernel Image and the initramfs Image:* Build your kernel - image using BitBake. Because the initramfs image recipe is a - dependency of the kernel image, the initramfs image is built as well - and bundled with the kernel image if you used the - :term:`INITRAMFS_IMAGE_BUNDLE` - variable described earlier. - -Bundling an Initramfs Image From a Separate Multiconfig -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -There may be a case where we want to build an initramfs image which does not -inherit the same distro policy as our main image, for example, we may want -our main image to use ``TCLIBC="glibc"``, but to use ``TCLIBC="musl"`` in our initramfs -image to keep a smaller footprint. However, by performing the steps mentioned -above the initramfs image will inherit ``TCLIBC="glibc"`` without allowing us -to override it. - -To achieve this, you need to perform some additional steps: - -1. *Create a multiconfig for your initramfs image:* You can perform the steps - on ":ref:`dev-manual/common-tasks:building images for multiple targets using multiple configurations`" to create a separate multiconfig. - For the sake of simplicity let's assume such multiconfig is called: ``initramfscfg.conf`` and - contains the variables:: - - TMPDIR="${TOPDIR}/tmp-initramfscfg" - TCLIBC="musl" - -2. *Set additional initramfs variables on your main configuration:* - Additionally, on your main configuration (``local.conf``) you need to set the - variables:: - - INITRAMFS_MULTICONFIG = "initramfscfg" - INITRAMFS_DEPLOY_DIR_IMAGE = "${TOPDIR}/tmp-initramfscfg/deploy/images/${MACHINE}" - - The variables :term:`INITRAMFS_MULTICONFIG` and :term:`INITRAMFS_DEPLOY_DIR_IMAGE` - are used to create a multiconfig dependency from the kernel to the :term:`INITRAMFS_IMAGE` - to be built coming from the ``initramfscfg`` multiconfig, and to let the - buildsystem know where the :term:`INITRAMFS_IMAGE` will be located. - - Building a system with such configuration will build the kernel using the - main configuration but the ``do_bundle_initramfs`` task will grab the - selected :term:`INITRAMFS_IMAGE` from :term:`INITRAMFS_DEPLOY_DIR_IMAGE` - instead, resulting in a musl based initramfs image bundled in the kernel - but a glibc based main image. - - The same is applicable to avoid inheriting :term:`DISTRO_FEATURES` on :term:`INITRAMFS_IMAGE` - or to build a different :term:`DISTRO` for it such as ``poky-tiny``. - - -Building a Tiny System ----------------------- - -Very small distributions have some significant advantages such as -requiring less on-die or in-package memory (cheaper), better performance -through efficient cache usage, lower power requirements due to less -memory, faster boot times, and reduced development overhead. Some -real-world examples where a very small distribution gives you distinct -advantages are digital cameras, medical devices, and small headless -systems. - -This section presents information that shows you how you can trim your -distribution to even smaller sizes than the ``poky-tiny`` distribution, -which is around 5 Mbytes, that can be built out-of-the-box using the -Yocto Project. - -Tiny System Overview -~~~~~~~~~~~~~~~~~~~~ - -The following list presents the overall steps you need to consider and -perform to create distributions with smaller root filesystems, achieve -faster boot times, maintain your critical functionality, and avoid -initial RAM disks: - -- :ref:`Determine your goals and guiding principles - ` - -- :ref:`dev-manual/common-tasks:understand what contributes to your image size` - -- :ref:`Reduce the size of the root filesystem - ` - -- :ref:`Reduce the size of the kernel ` - -- :ref:`dev-manual/common-tasks:remove package management requirements` - -- :ref:`dev-manual/common-tasks:look for other ways to minimize size` - -- :ref:`dev-manual/common-tasks:iterate on the process` - -Goals and Guiding Principles -~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Before you can reach your destination, you need to know where you are -going. Here is an example list that you can use as a guide when creating -very small distributions: - -- Determine how much space you need (e.g. a kernel that is 1 Mbyte or - less and a root filesystem that is 3 Mbytes or less). - -- Find the areas that are currently taking 90% of the space and - concentrate on reducing those areas. - -- Do not create any difficult "hacks" to achieve your goals. - -- Leverage the device-specific options. - -- Work in a separate layer so that you keep changes isolated. For - information on how to create layers, see the - ":ref:`dev-manual/common-tasks:understanding and creating layers`" section. - -Understand What Contributes to Your Image Size -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -It is easiest to have something to start with when creating your own -distribution. You can use the Yocto Project out-of-the-box to create the -``poky-tiny`` distribution. Ultimately, you will want to make changes in -your own distribution that are likely modeled after ``poky-tiny``. - -.. note:: - - To use ``poky-tiny`` in your build, set the :term:`DISTRO` variable in your - ``local.conf`` file to "poky-tiny" as described in the - ":ref:`dev-manual/common-tasks:creating your own distribution`" - section. - -Understanding some memory concepts will help you reduce the system size. -Memory consists of static, dynamic, and temporary memory. Static memory -is the TEXT (code), DATA (initialized data in the code), and BSS -(uninitialized data) sections. Dynamic memory represents memory that is -allocated at runtime: stacks, hash tables, and so forth. Temporary -memory is recovered after the boot process. This memory consists of -memory used for decompressing the kernel and for the ``__init__`` -functions. - -To help you see where you currently are with kernel and root filesystem -sizes, you can use two tools found in the :term:`Source Directory` -in the -``scripts/tiny/`` directory: - -- ``ksize.py``: Reports component sizes for the kernel build objects. - -- ``dirsize.py``: Reports component sizes for the root filesystem. - -This next tool and command help you organize configuration fragments and -view file dependencies in a human-readable form: - -- ``merge_config.sh``: Helps you manage configuration files and - fragments within the kernel. With this tool, you can merge individual - configuration fragments together. The tool allows you to make - overrides and warns you of any missing configuration options. The - tool is ideal for allowing you to iterate on configurations, create - minimal configurations, and create configuration files for different - machines without having to duplicate your process. - - The ``merge_config.sh`` script is part of the Linux Yocto kernel Git - repositories (i.e. ``linux-yocto-3.14``, ``linux-yocto-3.10``, - ``linux-yocto-3.8``, and so forth) in the ``scripts/kconfig`` - directory. - - For more information on configuration fragments, see the - ":ref:`kernel-dev/common:creating configuration fragments`" - section in the Yocto Project Linux Kernel Development Manual. - -- ``bitbake -u taskexp -g bitbake_target``: Using the BitBake command - with these options brings up a Dependency Explorer from which you can - view file dependencies. Understanding these dependencies allows you - to make informed decisions when cutting out various pieces of the - kernel and root filesystem. - -Trim the Root Filesystem -~~~~~~~~~~~~~~~~~~~~~~~~ - -The root filesystem is made up of packages for booting, libraries, and -applications. To change things, you can configure how the packaging -happens, which changes the way you build them. You can also modify the -filesystem itself or select a different filesystem. - -First, find out what is hogging your root filesystem by running the -``dirsize.py`` script from your root directory:: - - $ cd root-directory-of-image - $ dirsize.py 100000 > dirsize-100k.log - $ cat dirsize-100k.log - -You can apply a filter to the script to ignore files -under a certain size. The previous example filters out any files below -100 Kbytes. The sizes reported by the tool are uncompressed, and thus -will be smaller by a relatively constant factor in a compressed root -filesystem. When you examine your log file, you can focus on areas of -the root filesystem that take up large amounts of memory. - -You need to be sure that what you eliminate does not cripple the -functionality you need. One way to see how packages relate to each other -is by using the Dependency Explorer UI with the BitBake command:: - - $ cd image-directory - $ bitbake -u taskexp -g image - -Use the interface to -select potential packages you wish to eliminate and see their dependency -relationships. - -When deciding how to reduce the size, get rid of packages that result in -minimal impact on the feature set. For example, you might not need a VGA -display. Or, you might be able to get by with ``devtmpfs`` and ``mdev`` -instead of ``udev``. - -Use your ``local.conf`` file to make changes. For example, to eliminate -``udev`` and ``glib``, set the following in the local configuration -file:: - - VIRTUAL-RUNTIME_dev_manager = "" - -Finally, you should consider exactly the type of root filesystem you -need to meet your needs while also reducing its size. For example, -consider ``cramfs``, ``squashfs``, ``ubifs``, ``ext2``, or an -``initramfs`` using ``initramfs``. Be aware that ``ext3`` requires a 1 -Mbyte journal. If you are okay with running read-only, you do not need -this journal. - -.. note:: - - After each round of elimination, you need to rebuild your system and - then use the tools to see the effects of your reductions. - -Trim the Kernel -~~~~~~~~~~~~~~~ - -The kernel is built by including policies for hardware-independent -aspects. What subsystems do you enable? For what architecture are you -building? Which drivers do you build by default? - -.. note:: - - You can modify the kernel source if you want to help with boot time. - -Run the ``ksize.py`` script from the top-level Linux build directory to -get an idea of what is making up the kernel:: - - $ cd top-level-linux-build-directory - $ ksize.py > ksize.log - $ cat ksize.log - -When you examine the log, you will see how much space is taken up with -the built-in ``.o`` files for drivers, networking, core kernel files, -filesystem, sound, and so forth. The sizes reported by the tool are -uncompressed, and thus will be smaller by a relatively constant factor -in a compressed kernel image. Look to reduce the areas that are large -and taking up around the "90% rule." - -To examine, or drill down, into any particular area, use the ``-d`` -option with the script:: - - $ ksize.py -d > ksize.log - -Using this option -breaks out the individual file information for each area of the kernel -(e.g. drivers, networking, and so forth). - -Use your log file to see what you can eliminate from the kernel based on -features you can let go. For example, if you are not going to need -sound, you do not need any drivers that support sound. - -After figuring out what to eliminate, you need to reconfigure the kernel -to reflect those changes during the next build. You could run -``menuconfig`` and make all your changes at once. However, that makes it -difficult to see the effects of your individual eliminations and also -makes it difficult to replicate the changes for perhaps another target -device. A better method is to start with no configurations using -``allnoconfig``, create configuration fragments for individual changes, -and then manage the fragments into a single configuration file using -``merge_config.sh``. The tool makes it easy for you to iterate using the -configuration change and build cycle. - -Each time you make configuration changes, you need to rebuild the kernel -and check to see what impact your changes had on the overall size. - -Remove Package Management Requirements -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Packaging requirements add size to the image. One way to reduce the size -of the image is to remove all the packaging requirements from the image. -This reduction includes both removing the package manager and its unique -dependencies as well as removing the package management data itself. - -To eliminate all the packaging requirements for an image, be sure that -"package-management" is not part of your -:term:`IMAGE_FEATURES` -statement for the image. When you remove this feature, you are removing -the package manager as well as its dependencies from the root -filesystem. - -Look for Other Ways to Minimize Size -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Depending on your particular circumstances, other areas that you can -trim likely exist. The key to finding these areas is through tools and -methods described here combined with experimentation and iteration. Here -are a couple of areas to experiment with: - -- ``glibc``: In general, follow this process: - - 1. Remove ``glibc`` features from - :term:`DISTRO_FEATURES` - that you think you do not need. - - 2. Build your distribution. - - 3. If the build fails due to missing symbols in a package, determine - if you can reconfigure the package to not need those features. For - example, change the configuration to not support wide character - support as is done for ``ncurses``. Or, if support for those - characters is needed, determine what ``glibc`` features provide - the support and restore the configuration. - - 4. Rebuild and repeat the process. - -- ``busybox``: For BusyBox, use a process similar as described for - ``glibc``. A difference is you will need to boot the resulting system - to see if you are able to do everything you expect from the running - system. You need to be sure to integrate configuration fragments into - Busybox because BusyBox handles its own core features and then allows - you to add configuration fragments on top. - -Iterate on the Process -~~~~~~~~~~~~~~~~~~~~~~ - -If you have not reached your goals on system size, you need to iterate -on the process. The process is the same. Use the tools and see just what -is taking up 90% of the root filesystem and the kernel. Decide what you -can eliminate without limiting your device beyond what you need. - -Depending on your system, a good place to look might be Busybox, which -provides a stripped down version of Unix tools in a single, executable -file. You might be able to drop virtual terminal services or perhaps -ipv6. - -Building Images for More than One Machine ------------------------------------------ - -A common scenario developers face is creating images for several -different machines that use the same software environment. In this -situation, it is tempting to set the tunings and optimization flags for -each build specifically for the targeted hardware (i.e. "maxing out" the -tunings). Doing so can considerably add to build times and package feed -maintenance collectively for the machines. For example, selecting tunes -that are extremely specific to a CPU core used in a system might enable -some micro optimizations in GCC for that particular system but would -otherwise not gain you much of a performance difference across the other -systems as compared to using a more general tuning across all the builds -(e.g. setting :term:`DEFAULTTUNE` -specifically for each machine's build). Rather than "max out" each -build's tunings, you can take steps that cause the OpenEmbedded build -system to reuse software across the various machines where it makes -sense. - -If build speed and package feed maintenance are considerations, you -should consider the points in this section that can help you optimize -your tunings to best consider build times and package feed maintenance. - -- *Share the Build Directory:* If at all possible, share the - :term:`TMPDIR` across builds. The - Yocto Project supports switching between different - :term:`MACHINE` values in the same - :term:`TMPDIR`. This practice is well supported and regularly used by - developers when building for multiple machines. When you use the same - :term:`TMPDIR` for multiple machine builds, the OpenEmbedded build system - can reuse the existing native and often cross-recipes for multiple - machines. Thus, build time decreases. - - .. note:: - - If :term:`DISTRO` settings change or fundamental configuration settings - such as the filesystem layout, you need to work with a clean :term:`TMPDIR`. - Sharing :term:`TMPDIR` under these circumstances might work but since it is - not guaranteed, you should use a clean :term:`TMPDIR`. - -- *Enable the Appropriate Package Architecture:* By default, the - OpenEmbedded build system enables three levels of package - architectures: "all", "tune" or "package", and "machine". Any given - recipe usually selects one of these package architectures (types) for - its output. Depending for what a given recipe creates packages, - making sure you enable the appropriate package architecture can - directly impact the build time. - - A recipe that just generates scripts can enable "all" architecture - because there are no binaries to build. To specifically enable "all" - architecture, be sure your recipe inherits the - :ref:`allarch ` class. - This class is useful for "all" architectures because it configures - many variables so packages can be used across multiple architectures. - - If your recipe needs to generate packages that are machine-specific - or when one of the build or runtime dependencies is already - machine-architecture dependent, which makes your recipe also - machine-architecture dependent, make sure your recipe enables the - "machine" package architecture through the - :term:`MACHINE_ARCH` - variable:: - - PACKAGE_ARCH = "${MACHINE_ARCH}" - - When you do not - specifically enable a package architecture through the - :term:`PACKAGE_ARCH`, The - OpenEmbedded build system defaults to the - :term:`TUNE_PKGARCH` setting:: - - PACKAGE_ARCH = "${TUNE_PKGARCH}" - -- *Choose a Generic Tuning File if Possible:* Some tunes are more - generic and can run on multiple targets (e.g. an ``armv5`` set of - packages could run on ``armv6`` and ``armv7`` processors in most - cases). Similarly, ``i486`` binaries could work on ``i586`` and - higher processors. You should realize, however, that advances on - newer processor versions would not be used. - - If you select the same tune for several different machines, the - OpenEmbedded build system reuses software previously built, thus - speeding up the overall build time. Realize that even though a new - sysroot for each machine is generated, the software is not recompiled - and only one package feed exists. - -- *Manage Granular Level Packaging:* Sometimes there are cases where - injecting another level of package architecture beyond the three - higher levels noted earlier can be useful. For example, consider how - NXP (formerly Freescale) allows for the easy reuse of binary packages - in their layer - :yocto_git:`meta-freescale `. - In this example, the - :yocto_git:`fsl-dynamic-packagearch ` - class shares GPU packages for i.MX53 boards because all boards share - the AMD GPU. The i.MX6-based boards can do the same because all - boards share the Vivante GPU. This class inspects the BitBake - datastore to identify if the package provides or depends on one of - the sub-architecture values. If so, the class sets the - :term:`PACKAGE_ARCH` value - based on the ``MACHINE_SUBARCH`` value. If the package does not - provide or depend on one of the sub-architecture values but it - matches a value in the machine-specific filter, it sets - :term:`MACHINE_ARCH`. This - behavior reduces the number of packages built and saves build time by - reusing binaries. - -- *Use Tools to Debug Issues:* Sometimes you can run into situations - where software is being rebuilt when you think it should not be. For - example, the OpenEmbedded build system might not be using shared - state between machines when you think it should be. These types of - situations are usually due to references to machine-specific - variables such as :term:`MACHINE`, - :term:`SERIAL_CONSOLES`, - :term:`XSERVER`, - :term:`MACHINE_FEATURES`, - and so forth in code that is supposed to only be tune-specific or - when the recipe depends - (:term:`DEPENDS`, - :term:`RDEPENDS`, - :term:`RRECOMMENDS`, - :term:`RSUGGESTS`, and so forth) - on some other recipe that already has - :term:`PACKAGE_ARCH` defined - as "${MACHINE_ARCH}". - - .. note:: - - Patches to fix any issues identified are most welcome as these - issues occasionally do occur. - - For such cases, you can use some tools to help you sort out the - situation: - - - ``state-diff-machines.sh``*:* You can find this tool in the - ``scripts`` directory of the Source Repositories. See the comments - in the script for information on how to use the tool. - - - *BitBake's "-S printdiff" Option:* Using this option causes - BitBake to try to establish the closest signature match it can - (e.g. in the shared state cache) and then run ``bitbake-diffsigs`` - over the matches to determine the stamps and delta where these two - stamp trees diverge. - -Building Software from an External Source ------------------------------------------ - -By default, the OpenEmbedded build system uses the -:term:`Build Directory` when building source -code. The build process involves fetching the source files, unpacking -them, and then patching them if necessary before the build takes place. - -There are situations where you might want to build software from source -files that are external to and thus outside of the OpenEmbedded build -system. For example, suppose you have a project that includes a new BSP -with a heavily customized kernel. And, you want to minimize exposing the -build system to the development team so that they can focus on their -project and maintain everyone's workflow as much as possible. In this -case, you want a kernel source directory on the development machine -where the development occurs. You want the recipe's -:term:`SRC_URI` variable to point to -the external directory and use it as is, not copy it. - -To build from software that comes from an external source, all you need -to do is inherit the -:ref:`externalsrc ` class -and then set the -:term:`EXTERNALSRC` variable to -point to your external source code. Here are the statements to put in -your ``local.conf`` file:: - - INHERIT += "externalsrc" - EXTERNALSRC:pn-myrecipe = "path-to-your-source-tree" - -This next example shows how to accomplish the same thing by setting -:term:`EXTERNALSRC` in the recipe itself or in the recipe's append file:: - - EXTERNALSRC = "path" - EXTERNALSRC_BUILD = "path" - -.. note:: - - In order for these settings to take effect, you must globally or - locally inherit the :ref:`externalsrc ` - class. - -By default, :ref:`ref-classes-externalsrc` builds the source code in a -directory separate from the external source directory as specified by -:term:`EXTERNALSRC`. If you need -to have the source built in the same directory in which it resides, or -some other nominated directory, you can set -:term:`EXTERNALSRC_BUILD` -to point to that directory:: - - EXTERNALSRC_BUILD:pn-myrecipe = "path-to-your-source-tree" - -Replicating a Build Offline ---------------------------- - -It can be useful to take a "snapshot" of upstream sources used in a -build and then use that "snapshot" later to replicate the build offline. -To do so, you need to first prepare and populate your downloads -directory your "snapshot" of files. Once your downloads directory is -ready, you can use it at any time and from any machine to replicate your -build. - -Follow these steps to populate your Downloads directory: - -1. *Create a Clean Downloads Directory:* Start with an empty downloads - directory (:term:`DL_DIR`). You - start with an empty downloads directory by either removing the files - in the existing directory or by setting :term:`DL_DIR` to point to either - an empty location or one that does not yet exist. - -2. *Generate Tarballs of the Source Git Repositories:* Edit your - ``local.conf`` configuration file as follows:: - - DL_DIR = "/home/your-download-dir/" - BB_GENERATE_MIRROR_TARBALLS = "1" - - During - the fetch process in the next step, BitBake gathers the source files - and creates tarballs in the directory pointed to by :term:`DL_DIR`. See - the - :term:`BB_GENERATE_MIRROR_TARBALLS` - variable for more information. - -3. *Populate Your Downloads Directory Without Building:* Use BitBake to - fetch your sources but inhibit the build:: - - $ bitbake target --runonly=fetch - - The downloads directory (i.e. ``${DL_DIR}``) now has - a "snapshot" of the source files in the form of tarballs, which can - be used for the build. - -4. *Optionally Remove Any Git or other SCM Subdirectories From the - Downloads Directory:* If you want, you can clean up your downloads - directory by removing any Git or other Source Control Management - (SCM) subdirectories such as ``${DL_DIR}/git2/*``. The tarballs - already contain these subdirectories. - -Once your downloads directory has everything it needs regarding source -files, you can create your "own-mirror" and build your target. -Understand that you can use the files to build the target offline from -any machine and at any time. - -Follow these steps to build your target using the files in the downloads -directory: - -1. *Using Local Files Only:* Inside your ``local.conf`` file, add the - :term:`SOURCE_MIRROR_URL` variable, inherit the - :ref:`own-mirrors ` class, and use the - :term:`BB_NO_NETWORK` variable to your ``local.conf``. - :: - - SOURCE_MIRROR_URL ?= "file:///home/your-download-dir/" - INHERIT += "own-mirrors" - BB_NO_NETWORK = "1" - - The :term:`SOURCE_MIRROR_URL` and :ref:`own-mirrors ` - class set up the system to use the downloads directory as your "own - mirror". Using the :term:`BB_NO_NETWORK` variable makes sure that - BitBake's fetching process in step 3 stays local, which means files - from your "own-mirror" are used. - -2. *Start With a Clean Build:* You can start with a clean build by - removing the - ``${``\ :term:`TMPDIR`\ ``}`` - directory or using a new :term:`Build Directory`. - -3. *Build Your Target:* Use BitBake to build your target:: - - $ bitbake target - - The build completes using the known local "snapshot" of source - files from your mirror. The resulting tarballs for your "snapshot" of - source files are in the downloads directory. - - .. note:: - - The offline build does not work if recipes attempt to find the - latest version of software by setting - :term:`SRCREV` to - ``${``\ :term:`AUTOREV`\ ``}``:: - - SRCREV = "${AUTOREV}" - - When a recipe sets :term:`SRCREV` to - ``${``\ :term:`AUTOREV`\ ``}``, the build system accesses the network in an - attempt to determine the latest version of software from the SCM. - Typically, recipes that use :term:`AUTOREV` are custom or modified - recipes. Recipes that reside in public repositories usually do not - use :term:`AUTOREV`. - - If you do have recipes that use :term:`AUTOREV`, you can take steps to - still use the recipes in an offline build. Do the following: - - 1. Use a configuration generated by enabling :ref:`build - history `. - - 2. Use the ``buildhistory-collect-srcrevs`` command to collect the - stored :term:`SRCREV` values from the build's history. For more - information on collecting these values, see the - ":ref:`dev-manual/common-tasks:build history package information`" - section. - - 3. Once you have the correct source revisions, you can modify - those recipes to set :term:`SRCREV` to specific versions of the - software. - -Speeding Up a Build -=================== - -Build time can be an issue. By default, the build system uses simple -controls to try and maximize build efficiency. In general, the default -settings for all the following variables result in the most efficient -build times when dealing with single socket systems (i.e. a single CPU). -If you have multiple CPUs, you might try increasing the default values -to gain more speed. See the descriptions in the glossary for each -variable for more information: - -- :term:`BB_NUMBER_THREADS`: - The maximum number of threads BitBake simultaneously executes. - -- :term:`BB_NUMBER_PARSE_THREADS`: - The number of threads BitBake uses during parsing. - -- :term:`PARALLEL_MAKE`: Extra - options passed to the ``make`` command during the - :ref:`ref-tasks-compile` task in - order to specify parallel compilation on the local build host. - -- :term:`PARALLEL_MAKEINST`: - Extra options passed to the ``make`` command during the - :ref:`ref-tasks-install` task in - order to specify parallel installation on the local build host. - -As mentioned, these variables all scale to the number of processor cores -available on the build system. For single socket systems, this -auto-scaling ensures that the build system fundamentally takes advantage -of potential parallel operations during the build based on the build -machine's capabilities. - -Following are additional factors that can affect build speed: - -- File system type: The file system type that the build is being - performed on can also influence performance. Using ``ext4`` is - recommended as compared to ``ext2`` and ``ext3`` due to ``ext4`` - improved features such as extents. - -- Disabling the updating of access time using ``noatime``: The - ``noatime`` mount option prevents the build system from updating file - and directory access times. - -- Setting a longer commit: Using the "commit=" mount option increases - the interval in seconds between disk cache writes. Changing this - interval from the five second default to something longer increases - the risk of data loss but decreases the need to write to the disk, - thus increasing the build performance. - -- Choosing the packaging backend: Of the available packaging backends, - IPK is the fastest. Additionally, selecting a singular packaging - backend also helps. - -- Using ``tmpfs`` for :term:`TMPDIR` - as a temporary file system: While this can help speed up the build, - the benefits are limited due to the compiler using ``-pipe``. The - build system goes to some lengths to avoid ``sync()`` calls into the - file system on the principle that if there was a significant failure, - the :term:`Build Directory` - contents could easily be rebuilt. - -- Inheriting the - :ref:`rm_work ` class: - Inheriting this class has shown to speed up builds due to - significantly lower amounts of data stored in the data cache as well - as on disk. Inheriting this class also makes cleanup of - :term:`TMPDIR` faster, at the - expense of being easily able to dive into the source code. File - system maintainers have recommended that the fastest way to clean up - large numbers of files is to reformat partitions rather than delete - files due to the linear nature of partitions. This, of course, - assumes you structure the disk partitions and file systems in a way - that this is practical. - -Aside from the previous list, you should keep some trade offs in mind -that can help you speed up the build: - -- Remove items from - :term:`DISTRO_FEATURES` - that you might not need. - -- Exclude debug symbols and other debug information: If you do not need - these symbols and other debug information, disabling the ``*-dbg`` - package generation can speed up the build. You can disable this - generation by setting the - :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` - variable to "1". - -- Disable static library generation for recipes derived from - ``autoconf`` or ``libtool``: Following is an example showing how to - disable static libraries and still provide an override to handle - exceptions:: - - STATICLIBCONF = "--disable-static" - STATICLIBCONF:sqlite3-native = "" - EXTRA_OECONF += "${STATICLIBCONF}" - - .. note:: - - - Some recipes need static libraries in order to work correctly - (e.g. ``pseudo-native`` needs ``sqlite3-native``). Overrides, - as in the previous example, account for these kinds of - exceptions. - - - Some packages have packaging code that assumes the presence of - the static libraries. If so, you might need to exclude them as - well. - -Working With Libraries -====================== - -Libraries are an integral part of your system. This section describes -some common practices you might find helpful when working with libraries -to build your system: - -- :ref:`How to include static library files - ` - -- :ref:`How to use the Multilib feature to combine multiple versions of - library files into a single image - ` - -- :ref:`How to install multiple versions of the same library in parallel on - the same system - ` - -Including Static Library Files ------------------------------- - -If you are building a library and the library offers static linking, you -can control which static library files (``*.a`` files) get included in -the built library. - -The :term:`PACKAGES` and -:term:`FILES:* ` variables in the -``meta/conf/bitbake.conf`` configuration file define how files installed -by the ``do_install`` task are packaged. By default, the :term:`PACKAGES` -variable includes ``${PN}-staticdev``, which represents all static -library files. - -.. note:: - - Some previously released versions of the Yocto Project defined the - static library files through ``${PN}-dev``. - -Following is part of the BitBake configuration file, where you can see -how the static library files are defined:: - - PACKAGE_BEFORE_PN ?= "" - PACKAGES = "${PN}-src ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}" - PACKAGES_DYNAMIC = "^${PN}-locale-.*" - FILES = "" - - FILES:${PN} = "${bindir}/* ${sbindir}/* ${libexecdir}/* ${libdir}/lib*${SOLIBS} \ - ${sysconfdir} ${sharedstatedir} ${localstatedir} \ - ${base_bindir}/* ${base_sbindir}/* \ - ${base_libdir}/*${SOLIBS} \ - ${base_prefix}/lib/udev ${prefix}/lib/udev \ - ${base_libdir}/udev ${libdir}/udev \ - ${datadir}/${BPN} ${libdir}/${BPN}/* \ - ${datadir}/pixmaps ${datadir}/applications \ - ${datadir}/idl ${datadir}/omf ${datadir}/sounds \ - ${libdir}/bonobo/servers" - - FILES:${PN}-bin = "${bindir}/* ${sbindir}/*" - - FILES:${PN}-doc = "${docdir} ${mandir} ${infodir} ${datadir}/gtk-doc \ - ${datadir}/gnome/help" - SECTION:${PN}-doc = "doc" - - FILES_SOLIBSDEV ?= "${base_libdir}/lib*${SOLIBSDEV} ${libdir}/lib*${SOLIBSDEV}" - FILES:${PN}-dev = "${includedir} ${FILES_SOLIBSDEV} ${libdir}/*.la \ - ${libdir}/*.o ${libdir}/pkgconfig ${datadir}/pkgconfig \ - ${datadir}/aclocal ${base_libdir}/*.o \ - ${libdir}/${BPN}/*.la ${base_libdir}/*.la \ - ${libdir}/cmake ${datadir}/cmake" - SECTION:${PN}-dev = "devel" - ALLOW_EMPTY:${PN}-dev = "1" - RDEPENDS:${PN}-dev = "${PN} (= ${EXTENDPKGV})" - - FILES:${PN}-staticdev = "${libdir}/*.a ${base_libdir}/*.a ${libdir}/${BPN}/*.a" - SECTION:${PN}-staticdev = "devel" - RDEPENDS:${PN}-staticdev = "${PN}-dev (= ${EXTENDPKGV})" - -Combining Multiple Versions of Library Files into One Image ------------------------------------------------------------ - -The build system offers the ability to build libraries with different -target optimizations or architecture formats and combine these together -into one system image. You can link different binaries in the image -against the different libraries as needed for specific use cases. This -feature is called "Multilib". - -An example would be where you have most of a system compiled in 32-bit -mode using 32-bit libraries, but you have something large, like a -database engine, that needs to be a 64-bit application and uses 64-bit -libraries. Multilib allows you to get the best of both 32-bit and 64-bit -libraries. - -While the Multilib feature is most commonly used for 32 and 64-bit -differences, the approach the build system uses facilitates different -target optimizations. You could compile some binaries to use one set of -libraries and other binaries to use a different set of libraries. The -libraries could differ in architecture, compiler options, or other -optimizations. - -There are several examples in the ``meta-skeleton`` layer found in the -:term:`Source Directory`: - -- :oe_git:`conf/multilib-example.conf ` - configuration file. - -- :oe_git:`conf/multilib-example2.conf ` - configuration file. - -- :oe_git:`recipes-multilib/images/core-image-multilib-example.bb ` - recipe - -Preparing to Use Multilib -~~~~~~~~~~~~~~~~~~~~~~~~~ - -User-specific requirements drive the Multilib feature. Consequently, -there is no one "out-of-the-box" configuration that would -meet your needs. - -In order to enable Multilib, you first need to ensure your recipe is -extended to support multiple libraries. Many standard recipes are -already extended and support multiple libraries. You can check in the -``meta/conf/multilib.conf`` configuration file in the -:term:`Source Directory` to see how this is -done using the -:term:`BBCLASSEXTEND` variable. -Eventually, all recipes will be covered and this list will not be -needed. - -For the most part, the :ref:`Multilib ` -class extension works automatically to -extend the package name from ``${PN}`` to ``${MLPREFIX}${PN}``, where -:term:`MLPREFIX` is the particular multilib (e.g. "lib32-" or "lib64-"). -Standard variables such as -:term:`DEPENDS`, -:term:`RDEPENDS`, -:term:`RPROVIDES`, -:term:`RRECOMMENDS`, -:term:`PACKAGES`, and -:term:`PACKAGES_DYNAMIC` are -automatically extended by the system. If you are extending any manual -code in the recipe, you can use the ``${MLPREFIX}`` variable to ensure -those names are extended correctly. - -Using Multilib -~~~~~~~~~~~~~~ - -After you have set up the recipes, you need to define the actual -combination of multiple libraries you want to build. You accomplish this -through your ``local.conf`` configuration file in the -:term:`Build Directory`. An example -configuration would be as follows:: - - MACHINE = "qemux86-64" - require conf/multilib.conf - MULTILIBS = "multilib:lib32" - DEFAULTTUNE:virtclass-multilib-lib32 = "x86" - IMAGE_INSTALL:append = "lib32-glib-2.0" - -This example enables an additional library named -``lib32`` alongside the normal target packages. When combining these -"lib32" alternatives, the example uses "x86" for tuning. For information -on this particular tuning, see -``meta/conf/machine/include/ia32/arch-ia32.inc``. - -The example then includes ``lib32-glib-2.0`` in all the images, which -illustrates one method of including a multiple library dependency. You -can use a normal image build to include this dependency, for example:: - - $ bitbake core-image-sato - -You can also build Multilib packages -specifically with a command like this:: - - $ bitbake lib32-glib-2.0 - -Additional Implementation Details -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -There are generic implementation details as well as details that are specific to -package management systems. Following are implementation details -that exist regardless of the package management system: - -- The typical convention used for the class extension code as used by - Multilib assumes that all package names specified in - :term:`PACKAGES` that contain - ``${PN}`` have ``${PN}`` at the start of the name. When that - convention is not followed and ``${PN}`` appears at the middle or the - end of a name, problems occur. - -- The :term:`TARGET_VENDOR` - value under Multilib will be extended to "-vendormlmultilib" (e.g. - "-pokymllib32" for a "lib32" Multilib with Poky). The reason for this - slightly unwieldy contraction is that any "-" characters in the - vendor string presently break Autoconf's ``config.sub``, and other - separators are problematic for different reasons. - -Here are the implementation details for the RPM Package Management System: - -- A unique architecture is defined for the Multilib packages, along - with creating a unique deploy folder under ``tmp/deploy/rpm`` in the - :term:`Build Directory`. For - example, consider ``lib32`` in a ``qemux86-64`` image. The possible - architectures in the system are "all", "qemux86_64", - "lib32:qemux86_64", and "lib32:x86". - -- The ``${MLPREFIX}`` variable is stripped from ``${PN}`` during RPM - packaging. The naming for a normal RPM package and a Multilib RPM - package in a ``qemux86-64`` system resolves to something similar to - ``bash-4.1-r2.x86_64.rpm`` and ``bash-4.1.r2.lib32_x86.rpm``, - respectively. - -- When installing a Multilib image, the RPM backend first installs the - base image and then installs the Multilib libraries. - -- The build system relies on RPM to resolve the identical files in the - two (or more) Multilib packages. - -Here are the implementation details for the IPK Package Management System: - -- The ``${MLPREFIX}`` is not stripped from ``${PN}`` during IPK - packaging. The naming for a normal RPM package and a Multilib IPK - package in a ``qemux86-64`` system resolves to something like - ``bash_4.1-r2.x86_64.ipk`` and ``lib32-bash_4.1-rw:x86.ipk``, - respectively. - -- The IPK deploy folder is not modified with ``${MLPREFIX}`` because - packages with and without the Multilib feature can exist in the same - folder due to the ``${PN}`` differences. - -- IPK defines a sanity check for Multilib installation using certain - rules for file comparison, overridden, etc. - -Installing Multiple Versions of the Same Library ------------------------------------------------- - -There are be situations where you need to install and use multiple versions -of the same library on the same system at the same time. This -almost always happens when a library API changes and you have -multiple pieces of software that depend on the separate versions of the -library. To accommodate these situations, you can install multiple -versions of the same library in parallel on the same system. - -The process is straightforward as long as the libraries use proper -versioning. With properly versioned libraries, all you need to do to -individually specify the libraries is create separate, appropriately -named recipes where the :term:`PN` part of -the name includes a portion that differentiates each library version -(e.g. the major part of the version number). Thus, instead of having a -single recipe that loads one version of a library (e.g. ``clutter``), -you provide multiple recipes that result in different versions of the -libraries you want. As an example, the following two recipes would allow -the two separate versions of the ``clutter`` library to co-exist on the -same system: - -.. code-block:: none - - clutter-1.6_1.6.20.bb - clutter-1.8_1.8.4.bb - -Additionally, if -you have other recipes that depend on a given library, you need to use -the :term:`DEPENDS` variable to -create the dependency. Continuing with the same example, if you want to -have a recipe depend on the 1.8 version of the ``clutter`` library, use -the following in your recipe:: - - DEPENDS = "clutter-1.8" - -Working with Pre-Built Libraries -================================ - -Introduction -------------- - -Some library vendors do not release source code for their software but do -release pre-built binaries. When shared libraries are built, they should -be versioned (see `this article -`__ -for some background), but sometimes this is not done. - -To summarize, a versioned library must meet two conditions: - -#. The filename must have the version appended, for example: ``libfoo.so.1.2.3``. -#. The library must have the ELF tag ``SONAME`` set to the major version - of the library, for example: ``libfoo.so.1``. You can check this by - running ``readelf -d filename | grep SONAME``. - -This section shows how to deal with both versioned and unversioned -pre-built libraries. - -Versioned Libraries -------------------- - -In this example we work with pre-built libraries for the FT4222H USB I/O chip. -Libraries are built for several target architecture variants and packaged in -an archive as follows:: - - ├── build-arm-hisiv300 - │   └── libft4222.so.1.4.4.44 - ├── build-arm-v5-sf - │   └── libft4222.so.1.4.4.44 - ├── build-arm-v6-hf - │   └── libft4222.so.1.4.4.44 - ├── build-arm-v7-hf - │   └── libft4222.so.1.4.4.44 - ├── build-arm-v8 - │   └── libft4222.so.1.4.4.44 - ├── build-i386 - │   └── libft4222.so.1.4.4.44 - ├── build-i486 - │   └── libft4222.so.1.4.4.44 - ├── build-mips-eglibc-hf - │   └── libft4222.so.1.4.4.44 - ├── build-pentium - │   └── libft4222.so.1.4.4.44 - ├── build-x86_64 - │   └── libft4222.so.1.4.4.44 - ├── examples - │   ├── get-version.c - │   ├── i2cm.c - │   ├── spim.c - │   └── spis.c - ├── ftd2xx.h - ├── install4222.sh - ├── libft4222.h - ├── ReadMe.txt - └── WinTypes.h - -To write a recipe to use such a library in your system: - -- The vendor will probably have a proprietary licence, so set - :term:`LICENSE_FLAGS` in your recipe. -- The vendor provides a tarball containing libraries so set :term:`SRC_URI` - appropriately. -- Set :term:`COMPATIBLE_HOST` so that the recipe cannot be used with an - unsupported architecture. In the following example, we only support the 32 - and 64 bit variants of the ``x86`` architecture. -- As the vendor provides versioned libraries, we can use ``oe_soinstall`` - from :ref:`ref-classes-utils` to install the shared library and create - symbolic links. If the vendor does not do this, we need to follow the - non-versioned library guidelines in the next section. -- As the vendor likely used :term:`LDFLAGS` different from those in your Yocto - Project build, disable the corresponding checks by adding ``ldflags`` - to :term:`INSANE_SKIP`. -- The vendor will typically ship release builds without debugging symbols. - Avoid errors by preventing the packaging task from stripping out the symbols - and adding them to a separate debug package. This is done by setting the - ``INHIBIT_`` flags shown below. - -The complete recipe would look like this:: - - SUMMARY = "FTDI FT4222H Library" - SECTION = "libs" - LICENSE_FLAGS = "ftdi" - LICENSE = "CLOSED" - - COMPATIBLE_HOST = "(i.86|x86_64).*-linux" - - # Sources available in a .tgz file in .zip archive - # at https://ftdichip.com/wp-content/uploads/2021/01/libft4222-linux-1.4.4.44.zip - # Found on https://ftdichip.com/software-examples/ft4222h-software-examples/ - # Since dealing with this particular type of archive is out of topic here, - # we use a local link. - SRC_URI = "file://libft4222-linux-${PV}.tgz" - - S = "${WORKDIR}" - - ARCH_DIR:x86-64 = "build-x86_64" - ARCH_DIR:i586 = "build-i386" - ARCH_DIR:i686 = "build-i386" - - INSANE_SKIP:${PN} = "ldflags" - INHIBIT_PACKAGE_STRIP = "1" - INHIBIT_SYSROOT_STRIP = "1" - INHIBIT_PACKAGE_DEBUG_SPLIT = "1" - - do_install () { - install -m 0755 -d ${D}${libdir} - oe_soinstall ${S}/${ARCH_DIR}/libft4222.so.${PV} ${D}${libdir} - install -d ${D}${includedir} - install -m 0755 ${S}/*.h ${D}${includedir} - } - -If the precompiled binaries are not statically linked and have dependencies on -other libraries, then by adding those libraries to :term:`DEPENDS`, the linking -can be examined and the appropriate :term:`RDEPENDS` automatically added. - -Non-Versioned Libraries ------------------------ - -Some Background -~~~~~~~~~~~~~~~ - -Libraries in Linux systems are generally versioned so that it is possible -to have multiple versions of the same library installed, which eases upgrades -and support for older software. For example, suppose that in a versioned -library, an actual library is called ``libfoo.so.1.2``, a symbolic link named -``libfoo.so.1`` points to ``libfoo.so.1.2``, and a symbolic link named -``libfoo.so`` points to ``libfoo.so.1.2``. Given these conditions, when you -link a binary against a library, you typically provide the unversioned file -name (i.e. ``-lfoo`` to the linker). However, the linker follows the symbolic -link and actually links against the versioned filename. The unversioned symbolic -link is only used at development time. Consequently, the library is packaged -along with the headers in the development package ``${PN}-dev`` along with the -actual library and versioned symbolic links in ``${PN}``. Because versioned -libraries are far more common than unversioned libraries, the default packaging -rules assume versioned libraries. - -Yocto Library Packaging Overview -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -It follows that packaging an unversioned library requires a bit of work in the -recipe. By default, ``libfoo.so`` gets packaged into ``${PN}-dev``, which -triggers a QA warning that a non-symlink library is in a ``-dev`` package, -and binaries in the same recipe link to the library in ``${PN}-dev``, -which triggers more QA warnings. To solve this problem, you need to package the -unversioned library into ``${PN}`` where it belongs. The following are the abridged -default :term:`FILES` variables in ``bitbake.conf``:: - - SOLIBS = ".so.*" - SOLIBSDEV = ".so" - FILES:${PN} = "... ${libdir}/lib*${SOLIBS} ..." - FILES_SOLIBSDEV ?= "... ${libdir}/lib*${SOLIBSDEV} ..." - FILES:${PN}-dev = "... ${FILES_SOLIBSDEV} ..." - -:term:`SOLIBS` defines a pattern that matches real shared object libraries. -:term:`SOLIBSDEV` matches the development form (unversioned symlink). These two -variables are then used in ``FILES:${PN}`` and ``FILES:${PN}-dev``, which puts -the real libraries into ``${PN}`` and the unversioned symbolic link into ``${PN}-dev``. -To package unversioned libraries, you need to modify the variables in the recipe -as follows:: - - SOLIBS = ".so" - FILES_SOLIBSDEV = "" - -The modifications cause the ``.so`` file to be the real library -and unset :term:`FILES_SOLIBSDEV` so that no libraries get packaged into -``${PN}-dev``. The changes are required because unless :term:`PACKAGES` is changed, -``${PN}-dev`` collects files before `${PN}`. ``${PN}-dev`` must not collect any of -the files you want in ``${PN}``. - -Finally, loadable modules, essentially unversioned libraries that are linked -at runtime using ``dlopen()`` instead of at build time, should generally be -installed in a private directory. However, if they are installed in ``${libdir}``, -then the modules can be treated as unversioned libraries. - -Example -~~~~~~~ - -The example below installs an unversioned x86-64 pre-built library named -``libfoo.so``. The :term:`COMPATIBLE_HOST` variable limits recipes to the -x86-64 architecture while the :term:`INSANE_SKIP`, :term:`INHIBIT_PACKAGE_STRIP` -and :term:`INHIBIT_SYSROOT_STRIP` variables are all set as in the above -versioned library example. The "magic" is setting the :term:`SOLIBS` and -:term:`FILES_SOLIBSDEV` variables as explained above:: - - SUMMARY = "libfoo sample recipe" - SECTION = "libs" - LICENSE = "CLOSED" - - SRC_URI = "file://libfoo.so" - - COMPATIBLE_HOST = "x86_64.*-linux" - - INSANE_SKIP:${PN} = "ldflags" - INHIBIT_PACKAGE_STRIP = "1" - INHIBIT_SYSROOT_STRIP = "1" - SOLIBS = ".so" - FILES_SOLIBSDEV = "" - - do_install () { - install -d ${D}${libdir} - install -m 0755 ${WORKDIR}/libfoo.so ${D}${libdir} - } - -Using x32 psABI -=============== - -x32 processor-specific Application Binary Interface (`x32 -psABI `__) is a native -32-bit processor-specific ABI for Intel 64 (x86-64) architectures. An -ABI defines the calling conventions between functions in a processing -environment. The interface determines what registers are used and what -the sizes are for various C data types. - -Some processing environments prefer using 32-bit applications even when -running on Intel 64-bit platforms. Consider the i386 psABI, which is a -very old 32-bit ABI for Intel 64-bit platforms. The i386 psABI does not -provide efficient use and access of the Intel 64-bit processor -resources, leaving the system underutilized. Now consider the x86_64 -psABI. This ABI is newer and uses 64-bits for data sizes and program -pointers. The extra bits increase the footprint size of the programs, -libraries, and also increases the memory and file system size -requirements. Executing under the x32 psABI enables user programs to -utilize CPU and system resources more efficiently while keeping the -memory footprint of the applications low. Extra bits are used for -registers but not for addressing mechanisms. - -The Yocto Project supports the final specifications of x32 psABI as -follows: - -- You can create packages and images in x32 psABI format on x86_64 - architecture targets. - -- You can successfully build recipes with the x32 toolchain. - -- You can create and boot ``core-image-minimal`` and - ``core-image-sato`` images. - -- There is RPM Package Manager (RPM) support for x32 binaries. - -- There is support for large images. - -To use the x32 psABI, you need to edit your ``conf/local.conf`` -configuration file as follows:: - - MACHINE = "qemux86-64" - DEFAULTTUNE = "x86-64-x32" - baselib = "${@d.getVar('BASE_LIB:tune-' + (d.getVar('DEFAULTTUNE') \ - or 'INVALID')) or 'lib'}" - -Once you have set -up your configuration file, use BitBake to build an image that supports -the x32 psABI. Here is an example:: - - $ bitbake core-image-sato - -Enabling GObject Introspection Support -====================================== - -`GObject introspection `__ -is the standard mechanism for accessing GObject-based software from -runtime environments. GObject is a feature of the GLib library that -provides an object framework for the GNOME desktop and related software. -GObject Introspection adds information to GObject that allows objects -created within it to be represented across different programming -languages. If you want to construct GStreamer pipelines using Python, or -control UPnP infrastructure using Javascript and GUPnP, GObject -introspection is the only way to do it. - -This section describes the Yocto Project support for generating and -packaging GObject introspection data. GObject introspection data is a -description of the API provided by libraries built on top of the GLib -framework, and, in particular, that framework's GObject mechanism. -GObject Introspection Repository (GIR) files go to ``-dev`` packages, -``typelib`` files go to main packages as they are packaged together with -libraries that are introspected. - -The data is generated when building such a library, by linking the -library with a small executable binary that asks the library to describe -itself, and then executing the binary and processing its output. - -Generating this data in a cross-compilation environment is difficult -because the library is produced for the target architecture, but its -code needs to be executed on the build host. This problem is solved with -the OpenEmbedded build system by running the code through QEMU, which -allows precisely that. Unfortunately, QEMU does not always work -perfectly as mentioned in the ":ref:`dev-manual/common-tasks:known issues`" -section. - -Enabling the Generation of Introspection Data ---------------------------------------------- - -Enabling the generation of introspection data (GIR files) in your -library package involves the following: - -1. Inherit the - :ref:`gobject-introspection ` - class. - -2. Make sure introspection is not disabled anywhere in the recipe or - from anything the recipe includes. Also, make sure that - "gobject-introspection-data" is not in - :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED` - and that "qemu-usermode" is not in - :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`. - In either of these conditions, nothing will happen. - -3. Try to build the recipe. If you encounter build errors that look like - something is unable to find ``.so`` libraries, check where these - libraries are located in the source tree and add the following to the - recipe:: - - GIR_EXTRA_LIBS_PATH = "${B}/something/.libs" - - .. note:: - - See recipes in the ``oe-core`` repository that use that - :term:`GIR_EXTRA_LIBS_PATH` variable as an example. - -4. Look for any other errors, which probably mean that introspection - support in a package is not entirely standard, and thus breaks down - in a cross-compilation environment. For such cases, custom-made fixes - are needed. A good place to ask and receive help in these cases is - the :ref:`Yocto Project mailing - lists `. - -.. note:: - - Using a library that no longer builds against the latest Yocto - Project release and prints introspection related errors is a good - candidate for the previous procedure. - -Disabling the Generation of Introspection Data ----------------------------------------------- - -You might find that you do not want to generate introspection data. Or, -perhaps QEMU does not work on your build host and target architecture -combination. If so, you can use either of the following methods to -disable GIR file generations: - -- Add the following to your distro configuration:: - - DISTRO_FEATURES_BACKFILL_CONSIDERED = "gobject-introspection-data" - - Adding this statement disables generating introspection data using - QEMU but will still enable building introspection tools and libraries - (i.e. building them does not require the use of QEMU). - -- Add the following to your machine configuration:: - - MACHINE_FEATURES_BACKFILL_CONSIDERED = "qemu-usermode" - - Adding this statement disables the use of QEMU when building packages for your - machine. Currently, this feature is used only by introspection - recipes and has the same effect as the previously described option. - - .. note:: - - Future releases of the Yocto Project might have other features - affected by this option. - -If you disable introspection data, you can still obtain it through other -means such as copying the data from a suitable sysroot, or by generating -it on the target hardware. The OpenEmbedded build system does not -currently provide specific support for these techniques. - -Testing that Introspection Works in an Image --------------------------------------------- - -Use the following procedure to test if generating introspection data is -working in an image: - -1. Make sure that "gobject-introspection-data" is not in - :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED` - and that "qemu-usermode" is not in - :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`. - -2. Build ``core-image-sato``. - -3. Launch a Terminal and then start Python in the terminal. - -4. Enter the following in the terminal:: - - >>> from gi.repository import GLib - >>> GLib.get_host_name() - -5. For something a little more advanced, enter the following see: - https://python-gtk-3-tutorial.readthedocs.io/en/latest/introduction.html - -Known Issues ------------- - -Here are know issues in GObject Introspection Support: - -- ``qemu-ppc64`` immediately crashes. Consequently, you cannot build - introspection data on that architecture. - -- x32 is not supported by QEMU. Consequently, introspection data is - disabled. - -- musl causes transient GLib binaries to crash on assertion failures. - Consequently, generating introspection data is disabled. - -- Because QEMU is not able to run the binaries correctly, introspection - is disabled for some specific packages under specific architectures - (e.g. ``gcr``, ``libsecret``, and ``webkit``). - -- QEMU usermode might not work properly when running 64-bit binaries - under 32-bit host machines. In particular, "qemumips64" is known to - not work under i686. - -Optionally Using an External Toolchain -====================================== - -You might want to use an external toolchain as part of your development. -If this is the case, the fundamental steps you need to accomplish are as -follows: - -- Understand where the installed toolchain resides. For cases where you - need to build the external toolchain, you would need to take separate - steps to build and install the toolchain. - -- Make sure you add the layer that contains the toolchain to your - ``bblayers.conf`` file through the - :term:`BBLAYERS` variable. - -- Set the ``EXTERNAL_TOOLCHAIN`` variable in your ``local.conf`` file - to the location in which you installed the toolchain. - -A good example of an external toolchain used with the Yocto Project is -Mentor Graphics Sourcery G++ Toolchain. You can see information on how -to use that particular layer in the ``README`` file at -https://github.com/MentorEmbedded/meta-sourcery/. You can find -further information by reading about the -:term:`TCMODE` variable in the Yocto -Project Reference Manual's variable glossary. - -Creating Partitioned Images Using Wic -===================================== - -Creating an image for a particular hardware target using the -OpenEmbedded build system does not necessarily mean you can boot that -image as is on your device. Physical devices accept and boot images in -various ways depending on the specifics of the device. Usually, -information about the hardware can tell you what image format the device -requires. Should your device require multiple partitions on an SD card, -flash, or an HDD, you can use the OpenEmbedded Image Creator, Wic, to -create the properly partitioned image. - -The ``wic`` command generates partitioned images from existing -OpenEmbedded build artifacts. Image generation is driven by partitioning -commands contained in an Openembedded kickstart file (``.wks``) -specified either directly on the command line or as one of a selection -of canned kickstart files as shown with the ``wic list images`` command -in the -":ref:`dev-manual/common-tasks:generate an image using an existing kickstart file`" -section. When you apply the command to a given set of build artifacts, the -result is an image or set of images that can be directly written onto media and -used on a particular system. - -.. note:: - - For a kickstart file reference, see the - ":ref:`ref-manual/kickstart:openembedded kickstart (\`\`.wks\`\`) reference`" - Chapter in the Yocto Project Reference Manual. - -The ``wic`` command and the infrastructure it is based on is by -definition incomplete. The purpose of the command is to allow the -generation of customized images, and as such, was designed to be -completely extensible through a plugin interface. See the -":ref:`dev-manual/common-tasks:using the wic plugin interface`" section -for information on these plugins. - -This section provides some background information on Wic, describes what -you need to have in place to run the tool, provides instruction on how -to use the Wic utility, provides information on using the Wic plugins -interface, and provides several examples that show how to use Wic. - -Background ----------- - -This section provides some background on the Wic utility. While none of -this information is required to use Wic, you might find it interesting. - -- The name "Wic" is derived from OpenEmbedded Image Creator (oeic). The - "oe" diphthong in "oeic" was promoted to the letter "w", because - "oeic" is both difficult to remember and to pronounce. - -- Wic is loosely based on the Meego Image Creator (``mic``) framework. - The Wic implementation has been heavily modified to make direct use - of OpenEmbedded build artifacts instead of package installation and - configuration, which are already incorporated within the OpenEmbedded - artifacts. - -- Wic is a completely independent standalone utility that initially - provides easier-to-use and more flexible replacements for an existing - functionality in OE-Core's - :ref:`image-live ` - class. The difference between Wic and those examples is that with Wic - the functionality of those scripts is implemented by a - general-purpose partitioning language, which is based on Redhat - kickstart syntax. - -Requirements ------------- - -In order to use the Wic utility with the OpenEmbedded Build system, your -system needs to meet the following requirements: - -- The Linux distribution on your development host must support the - Yocto Project. See the ":ref:`detailed-supported-distros`" - section in the Yocto Project Reference Manual for the list of - distributions that support the Yocto Project. - -- The standard system utilities, such as ``cp``, must be installed on - your development host system. - -- You must have sourced the build environment setup script (i.e. - :ref:`structure-core-script`) found in the - :term:`Build Directory`. - -- You need to have the build artifacts already available, which - typically means that you must have already created an image using the - Openembedded build system (e.g. ``core-image-minimal``). While it - might seem redundant to generate an image in order to create an image - using Wic, the current version of Wic requires the artifacts in the - form generated by the OpenEmbedded build system. - -- You must build several native tools, which are built to run on the - build system:: - - $ bitbake wic-tools - -- Include "wic" as part of the - :term:`IMAGE_FSTYPES` - variable. - -- Include the name of the :ref:`wic kickstart file ` - as part of the :term:`WKS_FILE` variable - -Getting Help ------------- - -You can get general help for the ``wic`` command by entering the ``wic`` -command by itself or by entering the command with a help argument as -follows:: - - $ wic -h - $ wic --help - $ wic help - -Currently, Wic supports seven commands: ``cp``, ``create``, ``help``, -``list``, ``ls``, ``rm``, and ``write``. You can get help for all these -commands except "help" by using the following form:: - - $ wic help command - -For example, the following command returns help for the ``write`` -command:: - - $ wic help write - -Wic supports help for three topics: ``overview``, ``plugins``, and -``kickstart``. You can get help for any topic using the following form:: - - $ wic help topic - -For example, the following returns overview help for Wic:: - - $ wic help overview - -There is one additional level of help for Wic. You can get help on -individual images through the ``list`` command. You can use the ``list`` -command to return the available Wic images as follows:: - - $ wic list images - genericx86 Create an EFI disk image for genericx86* - edgerouter Create SD card image for Edgerouter - beaglebone-yocto Create SD card image for Beaglebone - qemux86-directdisk Create a qemu machine 'pcbios' direct disk image - systemd-bootdisk Create an EFI disk image with systemd-boot - mkhybridiso Create a hybrid ISO image - mkefidisk Create an EFI disk image - sdimage-bootpart Create SD card image with a boot partition - directdisk-multi-rootfs Create multi rootfs image using rootfs plugin - directdisk Create a 'pcbios' direct disk image - directdisk-bootloader-config Create a 'pcbios' direct disk image with custom bootloader config - qemuriscv Create qcow2 image for RISC-V QEMU machines - directdisk-gpt Create a 'pcbios' direct disk image - efi-bootdisk - -Once you know the list of available -Wic images, you can use ``help`` with the command to get help on a -particular image. For example, the following command returns help on the -"beaglebone-yocto" image:: - - $ wic list beaglebone-yocto help - - Creates a partitioned SD card image for Beaglebone. - Boot files are located in the first vfat partition. - -Operational Modes ------------------ - -You can use Wic in two different modes, depending on how much control -you need for specifying the Openembedded build artifacts that are used -for creating the image: Raw and Cooked: - -- *Raw Mode:* You explicitly specify build artifacts through Wic - command-line arguments. - -- *Cooked Mode:* The current - :term:`MACHINE` setting and image - name are used to automatically locate and provide the build - artifacts. You just supply a kickstart file and the name of the image - from which to use artifacts. - -Regardless of the mode you use, you need to have the build artifacts -ready and available. - -Raw Mode -~~~~~~~~ - -Running Wic in raw mode allows you to specify all the partitions through -the ``wic`` command line. The primary use for raw mode is if you have -built your kernel outside of the Yocto Project -:term:`Build Directory`. In other words, you -can point to arbitrary kernel, root filesystem locations, and so forth. -Contrast this behavior with cooked mode where Wic looks in the Build -Directory (e.g. ``tmp/deploy/images/``\ machine). - -The general form of the ``wic`` command in raw mode is:: - - $ wic create wks_file options ... - - Where: - - wks_file: - An OpenEmbedded kickstart file. You can provide - your own custom file or use a file from a set of - existing files as described by further options. - - optional arguments: - -h, --help show this help message and exit - -o OUTDIR, --outdir OUTDIR - name of directory to create image in - -e IMAGE_NAME, --image-name IMAGE_NAME - name of the image to use the artifacts from e.g. core- - image-sato - -r ROOTFS_DIR, --rootfs-dir ROOTFS_DIR - path to the /rootfs dir to use as the .wks rootfs - source - -b BOOTIMG_DIR, --bootimg-dir BOOTIMG_DIR - path to the dir containing the boot artifacts (e.g. - /EFI or /syslinux dirs) to use as the .wks bootimg - source - -k KERNEL_DIR, --kernel-dir KERNEL_DIR - path to the dir containing the kernel to use in the - .wks bootimg - -n NATIVE_SYSROOT, --native-sysroot NATIVE_SYSROOT - path to the native sysroot containing the tools to use - to build the image - -s, --skip-build-check - skip the build check - -f, --build-rootfs build rootfs - -c {gzip,bzip2,xz}, --compress-with {gzip,bzip2,xz} - compress image with specified compressor - -m, --bmap generate .bmap - --no-fstab-update Do not change fstab file. - -v VARS_DIR, --vars VARS_DIR - directory with .env files that store bitbake - variables - -D, --debug output debug information - -.. note:: - - You do not need root privileges to run Wic. In fact, you should not - run as root when using the utility. - -Cooked Mode -~~~~~~~~~~~ - -Running Wic in cooked mode leverages off artifacts in the Build -Directory. In other words, you do not have to specify kernel or root -filesystem locations as part of the command. All you need to provide is -a kickstart file and the name of the image from which to use artifacts -by using the "-e" option. Wic looks in the Build Directory (e.g. -``tmp/deploy/images/``\ machine) for artifacts. - -The general form of the ``wic`` command using Cooked Mode is as follows:: - - $ wic create wks_file -e IMAGE_NAME - - Where: - - wks_file: - An OpenEmbedded kickstart file. You can provide - your own custom file or use a file from a set of - existing files provided with the Yocto Project - release. - - required argument: - -e IMAGE_NAME, --image-name IMAGE_NAME - name of the image to use the artifacts from e.g. core- - image-sato - -Using an Existing Kickstart File --------------------------------- - -If you do not want to create your own kickstart file, you can use an -existing file provided by the Wic installation. As shipped, kickstart -files can be found in the :ref:`overview-manual/development-environment:yocto project source repositories` in the -following two locations:: - - poky/meta-yocto-bsp/wic - poky/scripts/lib/wic/canned-wks - -Use the following command to list the available kickstart files:: - - $ wic list images - genericx86 Create an EFI disk image for genericx86* - beaglebone-yocto Create SD card image for Beaglebone - edgerouter Create SD card image for Edgerouter - qemux86-directdisk Create a QEMU machine 'pcbios' direct disk image - directdisk-gpt Create a 'pcbios' direct disk image - mkefidisk Create an EFI disk image - directdisk Create a 'pcbios' direct disk image - systemd-bootdisk Create an EFI disk image with systemd-boot - mkhybridiso Create a hybrid ISO image - sdimage-bootpart Create SD card image with a boot partition - directdisk-multi-rootfs Create multi rootfs image using rootfs plugin - directdisk-bootloader-config Create a 'pcbios' direct disk image with custom bootloader config - -When you use an existing file, you -do not have to use the ``.wks`` extension. Here is an example in Raw -Mode that uses the ``directdisk`` file:: - - $ wic create directdisk -r rootfs_dir -b bootimg_dir \ - -k kernel_dir -n native_sysroot - -Here are the actual partition language commands used in the -``genericx86.wks`` file to generate an image:: - - # short-description: Create an EFI disk image for genericx86* - # long-description: Creates a partitioned EFI disk image for genericx86* machines - part /boot --source bootimg-efi --sourceparams="loader=grub-efi" --ondisk sda --label msdos --active --align 1024 - part / --source rootfs --ondisk sda --fstype=ext4 --label platform --align 1024 --use-uuid - part swap --ondisk sda --size 44 --label swap1 --fstype=swap - - bootloader --ptable gpt --timeout=5 --append="rootfstype=ext4 console=ttyS0,115200 console=tty0" - -Using the Wic Plugin Interface ------------------------------- - -You can extend and specialize Wic functionality by using Wic plugins. -This section explains the Wic plugin interface. - -.. note:: - - Wic plugins consist of "source" and "imager" plugins. Imager plugins - are beyond the scope of this section. - -Source plugins provide a mechanism to customize partition content during -the Wic image generation process. You can use source plugins to map -values that you specify using ``--source`` commands in kickstart files -(i.e. ``*.wks``) to a plugin implementation used to populate a given -partition. - -.. note:: - - If you use plugins that have build-time dependencies (e.g. native - tools, bootloaders, and so forth) when building a Wic image, you need - to specify those dependencies using the :term:`WKS_FILE_DEPENDS` - variable. - -Source plugins are subclasses defined in plugin files. As shipped, the -Yocto Project provides several plugin files. You can see the source -plugin files that ship with the Yocto Project -:yocto_git:`here `. -Each of these plugin files contains source plugins that are designed to -populate a specific Wic image partition. - -Source plugins are subclasses of the ``SourcePlugin`` class, which is -defined in the ``poky/scripts/lib/wic/pluginbase.py`` file. For example, -the ``BootimgEFIPlugin`` source plugin found in the ``bootimg-efi.py`` -file is a subclass of the ``SourcePlugin`` class, which is found in the -``pluginbase.py`` file. - -You can also implement source plugins in a layer outside of the Source -Repositories (external layer). To do so, be sure that your plugin files -are located in a directory whose path is -``scripts/lib/wic/plugins/source/`` within your external layer. When the -plugin files are located there, the source plugins they contain are made -available to Wic. - -When the Wic implementation needs to invoke a partition-specific -implementation, it looks for the plugin with the same name as the -``--source`` parameter used in the kickstart file given to that -partition. For example, if the partition is set up using the following -command in a kickstart file:: - - part /boot --source bootimg-pcbios --ondisk sda --label boot --active --align 1024 - -The methods defined as class -members of the matching source plugin (i.e. ``bootimg-pcbios``) in the -``bootimg-pcbios.py`` plugin file are used. - -To be more concrete, here is the corresponding plugin definition from -the ``bootimg-pcbios.py`` file for the previous command along with an -example method called by the Wic implementation when it needs to prepare -a partition using an implementation-specific function:: - - . - . - . - class BootimgPcbiosPlugin(SourcePlugin): - """ - Create MBR boot partition and install syslinux on it. - """ - - name = 'bootimg-pcbios' - . - . - . - @classmethod - def do_prepare_partition(cls, part, source_params, creator, cr_workdir, - oe_builddir, bootimg_dir, kernel_dir, - rootfs_dir, native_sysroot): - """ - Called to do the actual content population for a partition i.e. it - 'prepares' the partition to be incorporated into the image. - In this case, prepare content for legacy bios boot partition. - """ - . - . - . - -If a -subclass (plugin) itself does not implement a particular function, Wic -locates and uses the default version in the superclass. It is for this -reason that all source plugins are derived from the ``SourcePlugin`` -class. - -The ``SourcePlugin`` class defined in the ``pluginbase.py`` file defines -a set of methods that source plugins can implement or override. Any -plugins (subclass of ``SourcePlugin``) that do not implement a -particular method inherit the implementation of the method from the -``SourcePlugin`` class. For more information, see the ``SourcePlugin`` -class in the ``pluginbase.py`` file for details: - -The following list describes the methods implemented in the -``SourcePlugin`` class: - -- ``do_prepare_partition()``: Called to populate a partition with - actual content. In other words, the method prepares the final - partition image that is incorporated into the disk image. - -- ``do_configure_partition()``: Called before - ``do_prepare_partition()`` to create custom configuration files for a - partition (e.g. syslinux or grub configuration files). - -- ``do_install_disk()``: Called after all partitions have been - prepared and assembled into a disk image. This method provides a hook - to allow finalization of a disk image (e.g. writing an MBR). - -- ``do_stage_partition()``: Special content-staging hook called - before ``do_prepare_partition()``. This method is normally empty. - - Typically, a partition just uses the passed-in parameters (e.g. the - unmodified value of ``bootimg_dir``). However, in some cases, things - might need to be more tailored. As an example, certain files might - additionally need to be taken from ``bootimg_dir + /boot``. This hook - allows those files to be staged in a customized fashion. - - .. note:: - - ``get_bitbake_var()`` allows you to access non-standard variables that - you might want to use for this behavior. - -You can extend the source plugin mechanism. To add more hooks, create -more source plugin methods within ``SourcePlugin`` and the corresponding -derived subclasses. The code that calls the plugin methods uses the -``plugin.get_source_plugin_methods()`` function to find the method or -methods needed by the call. Retrieval of those methods is accomplished -by filling up a dict with keys that contain the method names of -interest. On success, these will be filled in with the actual methods. -See the Wic implementation for examples and details. - -Wic Examples ------------- - -This section provides several examples that show how to use the Wic -utility. All the examples assume the list of requirements in the -":ref:`dev-manual/common-tasks:requirements`" section have been met. The -examples assume the previously generated image is -``core-image-minimal``. - -Generate an Image using an Existing Kickstart File -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -This example runs in Cooked Mode and uses the ``mkefidisk`` kickstart -file:: - - $ wic create mkefidisk -e core-image-minimal - INFO: Building wic-tools... - . - . - . - INFO: The new image(s) can be found here: - ./mkefidisk-201804191017-sda.direct - - The following build artifacts were used to create the image(s): - ROOTFS_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/rootfs - BOOTIMG_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share - KERNEL_DIR: /home/stephano/yocto/build/tmp-glibc/deploy/images/qemux86 - NATIVE_SYSROOT: /home/stephano/yocto/build/tmp-glibc/work/i586-oe-linux/wic-tools/1.0-r0/recipe-sysroot-native - - INFO: The image(s) were created using OE kickstart file: - /home/stephano/yocto/openembedded-core/scripts/lib/wic/canned-wks/mkefidisk.wks - -The previous example shows the easiest way to create an image by running -in cooked mode and supplying a kickstart file and the "-e" option to -point to the existing build artifacts. Your ``local.conf`` file needs to -have the :term:`MACHINE` variable set -to the machine you are using, which is "qemux86" in this example. - -Once the image builds, the output provides image location, artifact use, -and kickstart file information. - -.. note:: - - You should always verify the details provided in the output to make - sure that the image was indeed created exactly as expected. - -Continuing with the example, you can now write the image from the Build -Directory onto a USB stick, or whatever media for which you built your -image, and boot from the media. You can write the image by using -``bmaptool`` or ``dd``:: - - $ oe-run-native bmaptool copy mkefidisk-201804191017-sda.direct /dev/sdX - -or :: - - $ sudo dd if=mkefidisk-201804191017-sda.direct of=/dev/sdX - -.. note:: - - For more information on how to use the ``bmaptool`` - to flash a device with an image, see the - ":ref:`dev-manual/common-tasks:flashing images using \`\`bmaptool\`\``" - section. - -Using a Modified Kickstart File -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Because partitioned image creation is driven by the kickstart file, it -is easy to affect image creation by changing the parameters in the file. -This next example demonstrates that through modification of the -``directdisk-gpt`` kickstart file. - -As mentioned earlier, you can use the command ``wic list images`` to -show the list of existing kickstart files. The directory in which the -``directdisk-gpt.wks`` file resides is -``scripts/lib/image/canned-wks/``, which is located in the -:term:`Source Directory` (e.g. ``poky``). -Because available files reside in this directory, you can create and add -your own custom files to the directory. Subsequent use of the -``wic list images`` command would then include your kickstart files. - -In this example, the existing ``directdisk-gpt`` file already does most -of what is needed. However, for the hardware in this example, the image -will need to boot from ``sdb`` instead of ``sda``, which is what the -``directdisk-gpt`` kickstart file uses. - -The example begins by making a copy of the ``directdisk-gpt.wks`` file -in the ``scripts/lib/image/canned-wks`` directory and then by changing -the lines that specify the target disk from which to boot. -:: - - $ cp /home/stephano/yocto/poky/scripts/lib/wic/canned-wks/directdisk-gpt.wks \ - /home/stephano/yocto/poky/scripts/lib/wic/canned-wks/directdisksdb-gpt.wks - -Next, the example modifies the ``directdisksdb-gpt.wks`` file and -changes all instances of "``--ondisk sda``" to "``--ondisk sdb``". The -example changes the following two lines and leaves the remaining lines -untouched:: - - part /boot --source bootimg-pcbios --ondisk sdb --label boot --active --align 1024 - part / --source rootfs --ondisk sdb --fstype=ext4 --label platform --align 1024 --use-uuid - -Once the lines are changed, the -example generates the ``directdisksdb-gpt`` image. The command points -the process at the ``core-image-minimal`` artifacts for the Next Unit of -Computing (nuc) :term:`MACHINE` the -``local.conf``. -:: - - $ wic create directdisksdb-gpt -e core-image-minimal - INFO: Building wic-tools... - . - . - . - Initialising tasks: 100% |#######################################| Time: 0:00:01 - NOTE: Executing SetScene Tasks - NOTE: Executing RunQueue Tasks - NOTE: Tasks Summary: Attempted 1161 tasks of which 1157 didn't need to be rerun and all succeeded. - INFO: Creating image(s)... - - INFO: The new image(s) can be found here: - ./directdisksdb-gpt-201710090938-sdb.direct - - The following build artifacts were used to create the image(s): - ROOTFS_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/rootfs - BOOTIMG_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share - KERNEL_DIR: /home/stephano/yocto/build/tmp-glibc/deploy/images/qemux86 - NATIVE_SYSROOT: /home/stephano/yocto/build/tmp-glibc/work/i586-oe-linux/wic-tools/1.0-r0/recipe-sysroot-native - - INFO: The image(s) were created using OE kickstart file: - /home/stephano/yocto/poky/scripts/lib/wic/canned-wks/directdisksdb-gpt.wks - -Continuing with the example, you can now directly ``dd`` the image to a -USB stick, or whatever media for which you built your image, and boot -the resulting media:: - - $ sudo dd if=directdisksdb-gpt-201710090938-sdb.direct of=/dev/sdb - 140966+0 records in - 140966+0 records out - 72174592 bytes (72 MB, 69 MiB) copied, 78.0282 s, 925 kB/s - $ sudo eject /dev/sdb - -Using a Modified Kickstart File and Running in Raw Mode -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -This next example manually specifies each build artifact (runs in Raw -Mode) and uses a modified kickstart file. The example also uses the -``-o`` option to cause Wic to create the output somewhere other than the -default output directory, which is the current directory:: - - $ wic create test.wks -o /home/stephano/testwic \ - --rootfs-dir /home/stephano/yocto/build/tmp/work/qemux86-poky-linux/core-image-minimal/1.0-r0/rootfs \ - --bootimg-dir /home/stephano/yocto/build/tmp/work/qemux86-poky-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share \ - --kernel-dir /home/stephano/yocto/build/tmp/deploy/images/qemux86 \ - --native-sysroot /home/stephano/yocto/build/tmp/work/i586-poky-linux/wic-tools/1.0-r0/recipe-sysroot-native - - INFO: Creating image(s)... - - INFO: The new image(s) can be found here: - /home/stephano/testwic/test-201710091445-sdb.direct - - The following build artifacts were used to create the image(s): - ROOTFS_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/rootfs - BOOTIMG_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share - KERNEL_DIR: /home/stephano/yocto/build/tmp-glibc/deploy/images/qemux86 - NATIVE_SYSROOT: /home/stephano/yocto/build/tmp-glibc/work/i586-oe-linux/wic-tools/1.0-r0/recipe-sysroot-native - - INFO: The image(s) were created using OE kickstart file: - test.wks - -For this example, -:term:`MACHINE` did not have to be -specified in the ``local.conf`` file since the artifact is manually -specified. - -Using Wic to Manipulate an Image -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Wic image manipulation allows you to shorten turnaround time during -image development. For example, you can use Wic to delete the kernel -partition of a Wic image and then insert a newly built kernel. This -saves you time from having to rebuild the entire image each time you -modify the kernel. - -.. note:: - - In order to use Wic to manipulate a Wic image as in this example, - your development machine must have the ``mtools`` package installed. - -The following example examines the contents of the Wic image, deletes -the existing kernel, and then inserts a new kernel: - -1. *List the Partitions:* Use the ``wic ls`` command to list all the - partitions in the Wic image:: - - $ wic ls tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic - Num Start End Size Fstype - 1 1048576 25041919 23993344 fat16 - 2 25165824 72157183 46991360 ext4 - - The previous output shows two partitions in the - ``core-image-minimal-qemux86.wic`` image. - -2. *Examine a Particular Partition:* Use the ``wic ls`` command again - but in a different form to examine a particular partition. - - .. note:: - - You can get command usage on any Wic command using the following - form:: - - $ wic help command - - - For example, the following command shows you the various ways to - use the - wic ls - command:: - - $ wic help ls - - - The following command shows what is in partition one:: - - $ wic ls tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic:1 - Volume in drive : is boot - Volume Serial Number is E894-1809 - Directory for ::/ - - libcom32 c32 186500 2017-10-09 16:06 - libutil c32 24148 2017-10-09 16:06 - syslinux cfg 220 2017-10-09 16:06 - vesamenu c32 27104 2017-10-09 16:06 - vmlinuz 6904608 2017-10-09 16:06 - 5 files 7 142 580 bytes - 16 582 656 bytes free - - The previous output shows five files, with the - ``vmlinuz`` being the kernel. - - .. note:: - - If you see the following error, you need to update or create a - ``~/.mtoolsrc`` file and be sure to have the line "mtools_skip_check=1" - in the file. Then, run the Wic command again:: - - ERROR: _exec_cmd: /usr/bin/mdir -i /tmp/wic-parttfokuwra ::/ returned '1' instead of 0 - output: Total number of sectors (47824) not a multiple of sectors per track (32)! - Add mtools_skip_check=1 to your .mtoolsrc file to skip this test - - -3. *Remove the Old Kernel:* Use the ``wic rm`` command to remove the - ``vmlinuz`` file (kernel):: - - $ wic rm tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic:1/vmlinuz - -4. *Add In the New Kernel:* Use the ``wic cp`` command to add the - updated kernel to the Wic image. Depending on how you built your - kernel, it could be in different places. If you used ``devtool`` and - an SDK to build your kernel, it resides in the ``tmp/work`` directory - of the extensible SDK. If you used ``make`` to build the kernel, the - kernel will be in the ``workspace/sources`` area. - - The following example assumes ``devtool`` was used to build the - kernel:: - - $ wic cp poky_sdk/tmp/work/qemux86-poky-linux/linux-yocto/4.12.12+git999-r0/linux-yocto-4.12.12+git999/arch/x86/boot/bzImage \ - poky/build/tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic:1/vmlinuz - - Once the new kernel is added back into the image, you can use the - ``dd`` command or :ref:`bmaptool - ` - to flash your wic image onto an SD card or USB stick and test your - target. - - .. note:: - - Using ``bmaptool`` is generally 10 to 20 times faster than using ``dd``. - -Flashing Images Using ``bmaptool`` -================================== - -A fast and easy way to flash an image to a bootable device is to use -Bmaptool, which is integrated into the OpenEmbedded build system. -Bmaptool is a generic tool that creates a file's block map (bmap) and -then uses that map to copy the file. As compared to traditional tools -such as dd or cp, Bmaptool can copy (or flash) large files like raw -system image files much faster. - -.. note:: - - - If you are using Ubuntu or Debian distributions, you can install - the ``bmap-tools`` package using the following command and then - use the tool without specifying ``PATH`` even from the root - account:: - - $ sudo apt install bmap-tools - - - If you are unable to install the ``bmap-tools`` package, you will - need to build Bmaptool before using it. Use the following command:: - - $ bitbake bmap-tools-native - -Following, is an example that shows how to flash a Wic image. Realize -that while this example uses a Wic image, you can use Bmaptool to flash -any type of image. Use these steps to flash an image using Bmaptool: - -1. *Update your local.conf File:* You need to have the following set - in your ``local.conf`` file before building your image:: - - IMAGE_FSTYPES += "wic wic.bmap" - -2. *Get Your Image:* Either have your image ready (pre-built with the - :term:`IMAGE_FSTYPES` - setting previously mentioned) or take the step to build the image:: - - $ bitbake image - -3. *Flash the Device:* Flash the device with the image by using Bmaptool - depending on your particular setup. The following commands assume the - image resides in the Build Directory's ``deploy/images/`` area: - - - If you have write access to the media, use this command form:: - - $ oe-run-native bmap-tools-native bmaptool copy build-directory/tmp/deploy/images/machine/image.wic /dev/sdX - - - If you do not have write access to the media, set your permissions - first and then use the same command form:: - - $ sudo chmod 666 /dev/sdX - $ oe-run-native bmap-tools-native bmaptool copy build-directory/tmp/deploy/images/machine/image.wic /dev/sdX - -For help on the ``bmaptool`` command, use the following command:: - - $ bmaptool --help - -Making Images More Secure -========================= - -Security is of increasing concern for embedded devices. Consider the -issues and problems discussed in just this sampling of work found across -the Internet: - -- *"*\ `Security Risks of Embedded - Systems `__\ *"* - by Bruce Schneier - -- *"*\ `Internet Census - 2012 `__\ *"* by Carna - Botnet - -- *"*\ `Security Issues for Embedded - Devices `__\ *"* - by Jake Edge - -When securing your image is of concern, there are steps, tools, and -variables that you can consider to help you reach the security goals you -need for your particular device. Not all situations are identical when -it comes to making an image secure. Consequently, this section provides -some guidance and suggestions for consideration when you want to make -your image more secure. - -.. note:: - - Because the security requirements and risks are different for every - type of device, this section cannot provide a complete reference on - securing your custom OS. It is strongly recommended that you also - consult other sources of information on embedded Linux system - hardening and on security. - -General Considerations ----------------------- - -There are general considerations that help you create more secure images. -You should consider the following suggestions to make your device -more secure: - -- Scan additional code you are adding to the system (e.g. application - code) by using static analysis tools. Look for buffer overflows and - other potential security problems. - -- Pay particular attention to the security for any web-based - administration interface. - - Web interfaces typically need to perform administrative functions and - tend to need to run with elevated privileges. Thus, the consequences - resulting from the interface's security becoming compromised can be - serious. Look for common web vulnerabilities such as - cross-site-scripting (XSS), unvalidated inputs, and so forth. - - As with system passwords, the default credentials for accessing a - web-based interface should not be the same across all devices. This - is particularly true if the interface is enabled by default as it can - be assumed that many end-users will not change the credentials. - -- Ensure you can update the software on the device to mitigate - vulnerabilities discovered in the future. This consideration - especially applies when your device is network-enabled. - -- Ensure you remove or disable debugging functionality before producing - the final image. For information on how to do this, see the - ":ref:`dev-manual/common-tasks:considerations specific to the openembedded build system`" - section. - -- Ensure you have no network services listening that are not needed. - -- Remove any software from the image that is not needed. - -- Enable hardware support for secure boot functionality when your - device supports this functionality. - -Security Flags --------------- - -The Yocto Project has security flags that you can enable that help make -your build output more secure. The security flags are in the -``meta/conf/distro/include/security_flags.inc`` file in your -:term:`Source Directory` (e.g. ``poky``). - -.. note:: - - Depending on the recipe, certain security flags are enabled and - disabled by default. - -Use the following line in your ``local.conf`` file or in your custom -distribution configuration file to enable the security compiler and -linker flags for your build:: - - require conf/distro/include/security_flags.inc - -Considerations Specific to the OpenEmbedded Build System --------------------------------------------------------- - -You can take some steps that are specific to the OpenEmbedded build -system to make your images more secure: - -- Ensure "debug-tweaks" is not one of your selected - :term:`IMAGE_FEATURES`. - When creating a new project, the default is to provide you with an - initial ``local.conf`` file that enables this feature using the - :term:`EXTRA_IMAGE_FEATURES` - variable with the line:: - - EXTRA_IMAGE_FEATURES = "debug-tweaks" - - To disable that feature, simply comment out that line in your - ``local.conf`` file, or make sure :term:`IMAGE_FEATURES` does not contain - "debug-tweaks" before producing your final image. Among other things, - leaving this in place sets the root password as blank, which makes - logging in for debugging or inspection easy during development but - also means anyone can easily log in during production. - -- It is possible to set a root password for the image and also to set - passwords for any extra users you might add (e.g. administrative or - service type users). When you set up passwords for multiple images or - users, you should not duplicate passwords. - - To set up passwords, use the - :ref:`extrausers ` - class, which is the preferred method. For an example on how to set up - both root and user passwords, see the - ":ref:`ref-classes-extrausers`" section. - - .. note:: - - When adding extra user accounts or setting a root password, be - cautious about setting the same password on every device. If you - do this, and the password you have set is exposed, then every - device is now potentially compromised. If you need this access but - want to ensure security, consider setting a different, random - password for each device. Typically, you do this as a separate - step after you deploy the image onto the device. - -- Consider enabling a Mandatory Access Control (MAC) framework such as - SMACK or SELinux and tuning it appropriately for your device's usage. - You can find more information in the - :yocto_git:`meta-selinux ` layer. - -Tools for Hardening Your Image ------------------------------- - -The Yocto Project provides tools for making your image more secure. You -can find these tools in the ``meta-security`` layer of the -:yocto_git:`Yocto Project Source Repositories <>`. - -Creating Your Own Distribution -============================== - -When you build an image using the Yocto Project and do not alter any -distribution :term:`Metadata`, you are -creating a Poky distribution. If you wish to gain more control over -package alternative selections, compile-time options, and other -low-level configurations, you can create your own distribution. - -To create your own distribution, the basic steps consist of creating -your own distribution layer, creating your own distribution -configuration file, and then adding any needed code and Metadata to the -layer. The following steps provide some more detail: - -- *Create a layer for your new distro:* Create your distribution layer - so that you can keep your Metadata and code for the distribution - separate. It is strongly recommended that you create and use your own - layer for configuration and code. Using your own layer as compared to - just placing configurations in a ``local.conf`` configuration file - makes it easier to reproduce the same build configuration when using - multiple build machines. See the - ":ref:`dev-manual/common-tasks:creating a general layer using the \`\`bitbake-layers\`\` script`" - section for information on how to quickly set up a layer. - -- *Create the distribution configuration file:* The distribution - configuration file needs to be created in the ``conf/distro`` - directory of your layer. You need to name it using your distribution - name (e.g. ``mydistro.conf``). - - .. note:: - - The :term:`DISTRO` variable in your ``local.conf`` file determines the - name of your distribution. - - You can split out parts of your configuration file into include files - and then "require" them from within your distribution configuration - file. Be sure to place the include files in the - ``conf/distro/include`` directory of your layer. A common example - usage of include files would be to separate out the selection of - desired version and revisions for individual recipes. - - Your configuration file needs to set the following required - variables: - - - :term:`DISTRO_NAME` - - - :term:`DISTRO_VERSION` - - These following variables are optional and you typically set them - from the distribution configuration file: - - - :term:`DISTRO_FEATURES` - - - :term:`DISTRO_EXTRA_RDEPENDS` - - - :term:`DISTRO_EXTRA_RRECOMMENDS` - - - :term:`TCLIBC` - - .. tip:: - - If you want to base your distribution configuration file on the - very basic configuration from OE-Core, you can use - ``conf/distro/defaultsetup.conf`` as a reference and just include - variables that differ as compared to ``defaultsetup.conf``. - Alternatively, you can create a distribution configuration file - from scratch using the ``defaultsetup.conf`` file or configuration files - from another distribution such as Poky as a reference. - -- *Provide miscellaneous variables:* Be sure to define any other - variables for which you want to create a default or enforce as part - of the distribution configuration. You can include nearly any - variable from the ``local.conf`` file. The variables you use are not - limited to the list in the previous bulleted item. - -- *Point to Your distribution configuration file:* In your - ``local.conf`` file in the :term:`Build Directory`, - set your - :term:`DISTRO` variable to point to - your distribution's configuration file. For example, if your - distribution's configuration file is named ``mydistro.conf``, then - you point to it as follows:: - - DISTRO = "mydistro" - -- *Add more to the layer if necessary:* Use your layer to hold other - information needed for the distribution: - - - Add recipes for installing distro-specific configuration files - that are not already installed by another recipe. If you have - distro-specific configuration files that are included by an - existing recipe, you should add an append file (``.bbappend``) for - those. For general information and recommendations on how to add - recipes to your layer, see the - ":ref:`dev-manual/common-tasks:creating your own layer`" and - ":ref:`dev-manual/common-tasks:following best practices when creating layers`" - sections. - - - Add any image recipes that are specific to your distribution. - - - Add a ``psplash`` append file for a branded splash screen. For - information on append files, see the - ":ref:`dev-manual/common-tasks:appending other layers metadata with your layer`" - section. - - - Add any other append files to make custom changes that are - specific to individual recipes. - -Creating a Custom Template Configuration Directory -================================================== - -If you are producing your own customized version of the build system for -use by other users, you might want to customize the message shown by the -setup script or you might want to change the template configuration -files (i.e. ``local.conf`` and ``bblayers.conf``) that are created in a -new build directory. - -The OpenEmbedded build system uses the environment variable -``TEMPLATECONF`` to locate the directory from which it gathers -configuration information that ultimately ends up in the -:term:`Build Directory` ``conf`` directory. -By default, ``TEMPLATECONF`` is set as follows in the ``poky`` -repository:: - - TEMPLATECONF=${TEMPLATECONF:-meta-poky/conf} - -This is the -directory used by the build system to find templates from which to build -some key configuration files. If you look at this directory, you will -see the ``bblayers.conf.sample``, ``local.conf.sample``, and -``conf-notes.txt`` files. The build system uses these files to form the -respective ``bblayers.conf`` file, ``local.conf`` file, and display the -list of BitBake targets when running the setup script. - -To override these default configuration files with configurations you -want used within every new Build Directory, simply set the -``TEMPLATECONF`` variable to your directory. The ``TEMPLATECONF`` -variable is set in the ``.templateconf`` file, which is in the top-level -:term:`Source Directory` folder -(e.g. ``poky``). Edit the ``.templateconf`` so that it can locate your -directory. - -Best practices dictate that you should keep your template configuration -directory in your custom distribution layer. For example, suppose you -have a layer named ``meta-mylayer`` located in your home directory and -you want your template configuration directory named ``myconf``. -Changing the ``.templateconf`` as follows causes the OpenEmbedded build -system to look in your directory and base its configuration files on the -``*.sample`` configuration files it finds. The final configuration files -(i.e. ``local.conf`` and ``bblayers.conf`` ultimately still end up in -your Build Directory, but they are based on your ``*.sample`` files. -:: - - TEMPLATECONF=${TEMPLATECONF:-meta-mylayer/myconf} - -Aside from the ``*.sample`` configuration files, the ``conf-notes.txt`` -also resides in the default ``meta-poky/conf`` directory. The script -that sets up the build environment (i.e. -:ref:`structure-core-script`) uses this file to -display BitBake targets as part of the script output. Customizing this -``conf-notes.txt`` file is a good way to make sure your list of custom -targets appears as part of the script's output. - -Here is the default list of targets displayed as a result of running -either of the setup scripts:: - - You can now run 'bitbake ' - - Common targets are: - core-image-minimal - core-image-sato - meta-toolchain - meta-ide-support - -Changing the listed common targets is as easy as editing your version of -``conf-notes.txt`` in your custom template configuration directory and -making sure you have ``TEMPLATECONF`` set to your directory. - -Conserving Disk Space -===================== - -Conserving Disk Space During Builds ------------------------------------ - -To help conserve disk space during builds, you can add the following -statement to your project's ``local.conf`` configuration file found in -the :term:`Build Directory`:: - - INHERIT += "rm_work" - -Adding this statement deletes the work directory used for -building a recipe once the recipe is built. For more information on -"rm_work", see the -:ref:`rm_work ` class in the -Yocto Project Reference Manual. - -Purging Duplicate Shared State Cache Files ------------------------------------------- - -After multiple build iterations, the Shared State (sstate) cache can contain -duplicate cache files for a given package, consuming a substantial amount of -disk space. However, only the most recent cache files are likeky to be reusable. - -The following command is a quick way to purge all the cache files which -haven't been used for a least a specified number of days:: - - find build/sstate-cache -type f -mtime +$DAYS -delete - -The above command relies on the fact that BitBake touches the sstate cache -files as it accesses them, when it has write access to the cache. - -You could use ``-atime`` instead of ``-mtime`` if the partition isn't mounted -with the ``noatime`` option for a read only cache. - -For more advanced needs, OpenEmbedded-Core also offers a more elaborate -command. It has the ability to purge all but the newest cache files on each -architecture, and also to remove files that it considers unreachable by -exploring a set of build configurations. However, this command -requires a full build environment to be available and doesn't work well -covering multiple releases. It won't work either on limited environments -such as BSD based NAS:: - - sstate-cache-management.sh --remove-duplicated --cache-dir=build/sstate-cache - -This command will ask you to confirm the deletions it identifies. -Run ``sstate-cache-management.sh`` for more details about this script. - -.. note:: - - As this command is much more cautious and selective, removing only cache files, - it will execute much slower than the simple ``find`` command described above. - Therefore, it may not be your best option to trim huge cache directories. - -Working with Packages -===================== - -This section describes a few tasks that involve packages: - -- :ref:`dev-manual/common-tasks:excluding packages from an image` - -- :ref:`dev-manual/common-tasks:incrementing a package version` - -- :ref:`dev-manual/common-tasks:handling optional module packaging` - -- :ref:`dev-manual/common-tasks:using runtime package management` - -- :ref:`dev-manual/common-tasks:generating and using signed packages` - -- :ref:`Setting up and running package test - (ptest) ` - -- :ref:`dev-manual/common-tasks:creating node package manager (npm) packages` - -- :ref:`dev-manual/common-tasks:adding custom metadata to packages` - -Excluding Packages from an Image --------------------------------- - -You might find it necessary to prevent specific packages from being -installed into an image. If so, you can use several variables to direct -the build system to essentially ignore installing recommended packages -or to not install a package at all. - -The following list introduces variables you can use to prevent packages -from being installed into your image. Each of these variables only works -with IPK and RPM package types, not for Debian packages. -Also, you can use these variables from your ``local.conf`` file -or attach them to a specific image recipe by using a recipe name -override. For more detail on the variables, see the descriptions in the -Yocto Project Reference Manual's glossary chapter. - -- :term:`BAD_RECOMMENDATIONS`: - Use this variable to specify "recommended-only" packages that you do - not want installed. - -- :term:`NO_RECOMMENDATIONS`: - Use this variable to prevent all "recommended-only" packages from - being installed. - -- :term:`PACKAGE_EXCLUDE`: - Use this variable to prevent specific packages from being installed - regardless of whether they are "recommended-only" or not. You need to - realize that the build process could fail with an error when you - prevent the installation of a package whose presence is required by - an installed package. - -Incrementing a Package Version ------------------------------- - -This section provides some background on how binary package versioning -is accomplished and presents some of the services, variables, and -terminology involved. - -In order to understand binary package versioning, you need to consider -the following: - -- Binary Package: The binary package that is eventually built and - installed into an image. - -- Binary Package Version: The binary package version is composed of two - components - a version and a revision. - - .. note:: - - Technically, a third component, the "epoch" (i.e. :term:`PE`) is involved - but this discussion for the most part ignores :term:`PE`. - - The version and revision are taken from the - :term:`PV` and - :term:`PR` variables, respectively. - -- :term:`PV`: The recipe version. :term:`PV` represents the version of the - software being packaged. Do not confuse :term:`PV` with the binary - package version. - -- :term:`PR`: The recipe revision. - -- :term:`SRCPV`: The OpenEmbedded - build system uses this string to help define the value of :term:`PV` when - the source code revision needs to be included in it. - -- :yocto_wiki:`PR Service `: A - network-based service that helps automate keeping package feeds - compatible with existing package manager applications such as RPM, - APT, and OPKG. - -Whenever the binary package content changes, the binary package version -must change. Changing the binary package version is accomplished by -changing or "bumping" the :term:`PR` and/or :term:`PV` values. Increasing these -values occurs one of two ways: - -- Automatically using a Package Revision Service (PR Service). - -- Manually incrementing the :term:`PR` and/or :term:`PV` variables. - -Given a primary challenge of any build system and its users is how to -maintain a package feed that is compatible with existing package manager -applications such as RPM, APT, and OPKG, using an automated system is -much preferred over a manual system. In either system, the main -requirement is that binary package version numbering increases in a -linear fashion and that there is a number of version components that -support that linear progression. For information on how to ensure -package revisioning remains linear, see the -":ref:`dev-manual/common-tasks:automatically incrementing a package version number`" -section. - -The following three sections provide related information on the PR -Service, the manual method for "bumping" :term:`PR` and/or :term:`PV`, and on -how to ensure binary package revisioning remains linear. - -Working With a PR Service -~~~~~~~~~~~~~~~~~~~~~~~~~ - -As mentioned, attempting to maintain revision numbers in the -:term:`Metadata` is error prone, inaccurate, -and causes problems for people submitting recipes. Conversely, the PR -Service automatically generates increasing numbers, particularly the -revision field, which removes the human element. - -.. note:: - - For additional information on using a PR Service, you can see the - :yocto_wiki:`PR Service ` wiki page. - -The Yocto Project uses variables in order of decreasing priority to -facilitate revision numbering (i.e. -:term:`PE`, -:term:`PV`, and -:term:`PR` for epoch, version, and -revision, respectively). The values are highly dependent on the policies -and procedures of a given distribution and package feed. - -Because the OpenEmbedded build system uses -":ref:`signatures `", which are -unique to a given build, the build system knows when to rebuild -packages. All the inputs into a given task are represented by a -signature, which can trigger a rebuild when different. Thus, the build -system itself does not rely on the :term:`PR`, :term:`PV`, and :term:`PE` numbers to -trigger a rebuild. The signatures, however, can be used to generate -these values. - -The PR Service works with both ``OEBasic`` and ``OEBasicHash`` -generators. The value of :term:`PR` bumps when the checksum changes and the -different generator mechanisms change signatures under different -circumstances. - -As implemented, the build system includes values from the PR Service -into the :term:`PR` field as an addition using the form "``.x``" so ``r0`` -becomes ``r0.1``, ``r0.2`` and so forth. This scheme allows existing -:term:`PR` values to be used for whatever reasons, which include manual -:term:`PR` bumps, should it be necessary. - -By default, the PR Service is not enabled or running. Thus, the packages -generated are just "self consistent". The build system adds and removes -packages and there are no guarantees about upgrade paths but images will -be consistent and correct with the latest changes. - -The simplest form for a PR Service is for a single host -development system that builds the package feed (building system). For -this scenario, you can enable a local PR Service by setting -:term:`PRSERV_HOST` in your -``local.conf`` file in the :term:`Build Directory`:: - - PRSERV_HOST = "localhost:0" - -Once the service is started, packages will automatically -get increasing :term:`PR` values and BitBake takes care of starting and -stopping the server. - -If you have a more complex setup where multiple host development systems -work against a common, shared package feed, you have a single PR Service -running and it is connected to each building system. For this scenario, -you need to start the PR Service using the ``bitbake-prserv`` command:: - - bitbake-prserv --host ip --port port --start - -In addition to -hand-starting the service, you need to update the ``local.conf`` file of -each building system as described earlier so each system points to the -server and port. - -It is also recommended you use build history, which adds some sanity -checks to binary package versions, in conjunction with the server that -is running the PR Service. To enable build history, add the following to -each building system's ``local.conf`` file:: - - # It is recommended to activate "buildhistory" for testing the PR service - INHERIT += "buildhistory" - BUILDHISTORY_COMMIT = "1" - -For information on build -history, see the -":ref:`dev-manual/common-tasks:maintaining build output quality`" section. - -.. note:: - - The OpenEmbedded build system does not maintain :term:`PR` information as - part of the shared state (sstate) packages. If you maintain an sstate - feed, it's expected that either all your building systems that - contribute to the sstate feed use a shared PR Service, or you do not - run a PR Service on any of your building systems. Having some systems - use a PR Service while others do not leads to obvious problems. - - For more information on shared state, see the - ":ref:`overview-manual/concepts:shared state cache`" - section in the Yocto Project Overview and Concepts Manual. - -Manually Bumping PR -~~~~~~~~~~~~~~~~~~~ - -The alternative to setting up a PR Service is to manually "bump" the -:term:`PR` variable. - -If a committed change results in changing the package output, then the -value of the PR variable needs to be increased (or "bumped") as part of -that commit. For new recipes you should add the :term:`PR` variable and set -its initial value equal to "r0", which is the default. Even though the -default value is "r0", the practice of adding it to a new recipe makes -it harder to forget to bump the variable when you make changes to the -recipe in future. - -If you are sharing a common ``.inc`` file with multiple recipes, you can -also use the :term:`INC_PR` variable to ensure that the recipes sharing the -``.inc`` file are rebuilt when the ``.inc`` file itself is changed. The -``.inc`` file must set :term:`INC_PR` (initially to "r0"), and all recipes -referring to it should set :term:`PR` to "${INC_PR}.0" initially, -incrementing the last number when the recipe is changed. If the ``.inc`` -file is changed then its :term:`INC_PR` should be incremented. - -When upgrading the version of a binary package, assuming the :term:`PV` -changes, the :term:`PR` variable should be reset to "r0" (or "${INC_PR}.0" -if you are using :term:`INC_PR`). - -Usually, version increases occur only to binary packages. However, if -for some reason :term:`PV` changes but does not increase, you can increase -the :term:`PE` variable (Package Epoch). The :term:`PE` variable defaults to -"0". - -Binary package version numbering strives to follow the `Debian Version -Field Policy -Guidelines `__. -These guidelines define how versions are compared and what "increasing" -a version means. - -Automatically Incrementing a Package Version Number -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -When fetching a repository, BitBake uses the -:term:`SRCREV` variable to determine -the specific source code revision from which to build. You set the -:term:`SRCREV` variable to -:term:`AUTOREV` to cause the -OpenEmbedded build system to automatically use the latest revision of -the software:: - - SRCREV = "${AUTOREV}" - -Furthermore, you need to reference :term:`SRCPV` in :term:`PV` in order to -automatically update the version whenever the revision of the source -code changes. Here is an example:: - - PV = "1.0+git${SRCPV}" - -The OpenEmbedded build system substitutes :term:`SRCPV` with the following: - -.. code-block:: none - - AUTOINC+source_code_revision - -The build system replaces the ``AUTOINC`` -with a number. The number used depends on the state of the PR Service: - -- If PR Service is enabled, the build system increments the number, - which is similar to the behavior of - :term:`PR`. This behavior results in - linearly increasing package versions, which is desirable. Here is an - example: - - .. code-block:: none - - hello-world-git_0.0+git0+b6558dd387-r0.0_armv7a-neon.ipk - hello-world-git_0.0+git1+dd2f5c3565-r0.0_armv7a-neon.ipk - -- If PR Service is not enabled, the build system replaces the - ``AUTOINC`` placeholder with zero (i.e. "0"). This results in - changing the package version since the source revision is included. - However, package versions are not increased linearly. Here is an - example: - - .. code-block:: none - - hello-world-git_0.0+git0+b6558dd387-r0.0_armv7a-neon.ipk - hello-world-git_0.0+git0+dd2f5c3565-r0.0_armv7a-neon.ipk - -In summary, the OpenEmbedded build system does not track the history of -binary package versions for this purpose. ``AUTOINC``, in this case, is -comparable to :term:`PR`. If PR server is not enabled, ``AUTOINC`` in the -package version is simply replaced by "0". If PR server is enabled, the -build system keeps track of the package versions and bumps the number -when the package revision changes. - -Handling Optional Module Packaging ----------------------------------- - -Many pieces of software split functionality into optional modules (or -plugins) and the plugins that are built might depend on configuration -options. To avoid having to duplicate the logic that determines what -modules are available in your recipe or to avoid having to package each -module by hand, the OpenEmbedded build system provides functionality to -handle module packaging dynamically. - -To handle optional module packaging, you need to do two things: - -- Ensure the module packaging is actually done. - -- Ensure that any dependencies on optional modules from other recipes - are satisfied by your recipe. - -Making Sure the Packaging is Done -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -To ensure the module packaging actually gets done, you use the -``do_split_packages`` function within the ``populate_packages`` Python -function in your recipe. The ``do_split_packages`` function searches for -a pattern of files or directories under a specified path and creates a -package for each one it finds by appending to the -:term:`PACKAGES` variable and -setting the appropriate values for ``FILES:packagename``, -``RDEPENDS:packagename``, ``DESCRIPTION:packagename``, and so forth. -Here is an example from the ``lighttpd`` recipe:: - - python populate_packages:prepend () { - lighttpd_libdir = d.expand('${libdir}') - do_split_packages(d, lighttpd_libdir, '^mod_(.*).so$', - 'lighttpd-module-%s', 'Lighttpd module for %s', - extra_depends='') - } - -The previous example specifies a number of things in the call to -``do_split_packages``. - -- A directory within the files installed by your recipe through - ``do_install`` in which to search. - -- A regular expression used to match module files in that directory. In - the example, note the parentheses () that mark the part of the - expression from which the module name should be derived. - -- A pattern to use for the package names. - -- A description for each package. - -- An empty string for ``extra_depends``, which disables the default - dependency on the main ``lighttpd`` package. Thus, if a file in - ``${libdir}`` called ``mod_alias.so`` is found, a package called - ``lighttpd-module-alias`` is created for it and the - :term:`DESCRIPTION` is set to - "Lighttpd module for alias". - -Often, packaging modules is as simple as the previous example. However, -there are more advanced options that you can use within -``do_split_packages`` to modify its behavior. And, if you need to, you -can add more logic by specifying a hook function that is called for each -package. It is also perfectly acceptable to call ``do_split_packages`` -multiple times if you have more than one set of modules to package. - -For more examples that show how to use ``do_split_packages``, see the -``connman.inc`` file in the ``meta/recipes-connectivity/connman/`` -directory of the ``poky`` :ref:`source repository `. You can -also find examples in ``meta/classes/kernel.bbclass``. - -Following is a reference that shows ``do_split_packages`` mandatory and -optional arguments:: - - Mandatory arguments - - root - The path in which to search - file_regex - Regular expression to match searched files. - Use parentheses () to mark the part of this - expression that should be used to derive the - module name (to be substituted where %s is - used in other function arguments as noted below) - output_pattern - Pattern to use for the package names. Must - include %s. - description - Description to set for each package. Must - include %s. - - Optional arguments - - postinst - Postinstall script to use for all packages - (as a string) - recursive - True to perform a recursive search - default - False - hook - A hook function to be called for every match. - The function will be called with the following - arguments (in the order listed): - - f - Full path to the file/directory match - pkg - The package name - file_regex - As above - output_pattern - As above - modulename - The module name derived using file_regex - extra_depends - Extra runtime dependencies (RDEPENDS) to be - set for all packages. The default value of None - causes a dependency on the main package - (${PN}) - if you do not want this, pass empty - string '' for this parameter. - aux_files_pattern - Extra item(s) to be added to FILES for each - package. Can be a single string item or a list - of strings for multiple items. Must include %s. - postrm - postrm script to use for all packages (as a - string) - allow_dirs - True to allow directories to be matched - - default False - prepend - If True, prepend created packages to PACKAGES - instead of the default False which appends them - match_path - match file_regex on the whole relative path to - the root rather than just the filename - aux_files_pattern_verbatim - Extra item(s) to be added to FILES for each - package, using the actual derived module name - rather than converting it to something legal - for a package name. Can be a single string item - or a list of strings for multiple items. Must - include %s. - allow_links - True to allow symlinks to be matched - default - False - summary - Summary to set for each package. Must include %s; - defaults to description if not set. - - - -Satisfying Dependencies -~~~~~~~~~~~~~~~~~~~~~~~ - -The second part for handling optional module packaging is to ensure that -any dependencies on optional modules from other recipes are satisfied by -your recipe. You can be sure these dependencies are satisfied by using -the :term:`PACKAGES_DYNAMIC` -variable. Here is an example that continues with the ``lighttpd`` recipe -shown earlier:: - - PACKAGES_DYNAMIC = "lighttpd-module-.*" - -The name -specified in the regular expression can of course be anything. In this -example, it is ``lighttpd-module-`` and is specified as the prefix to -ensure that any :term:`RDEPENDS` and -:term:`RRECOMMENDS` on a package -name starting with the prefix are satisfied during build time. If you -are using ``do_split_packages`` as described in the previous section, -the value you put in :term:`PACKAGES_DYNAMIC` should correspond to the name -pattern specified in the call to ``do_split_packages``. - -Using Runtime Package Management --------------------------------- - -During a build, BitBake always transforms a recipe into one or more -packages. For example, BitBake takes the ``bash`` recipe and produces a -number of packages (e.g. ``bash``, ``bash-bashbug``, -``bash-completion``, ``bash-completion-dbg``, ``bash-completion-dev``, -``bash-completion-extra``, ``bash-dbg``, and so forth). Not all -generated packages are included in an image. - -In several situations, you might need to update, add, remove, or query -the packages on a target device at runtime (i.e. without having to -generate a new image). Examples of such situations include: - -- You want to provide in-the-field updates to deployed devices (e.g. - security updates). - -- You want to have a fast turn-around development cycle for one or more - applications that run on your device. - -- You want to temporarily install the "debug" packages of various - applications on your device so that debugging can be greatly improved - by allowing access to symbols and source debugging. - -- You want to deploy a more minimal package selection of your device - but allow in-the-field updates to add a larger selection for - customization. - -In all these situations, you have something similar to a more -traditional Linux distribution in that in-field devices are able to -receive pre-compiled packages from a server for installation or update. -Being able to install these packages on a running, in-field device is -what is termed "runtime package management". - -In order to use runtime package management, you need a host or server -machine that serves up the pre-compiled packages plus the required -metadata. You also need package manipulation tools on the target. The -build machine is a likely candidate to act as the server. However, that -machine does not necessarily have to be the package server. The build -machine could push its artifacts to another machine that acts as the -server (e.g. Internet-facing). In fact, doing so is advantageous for a -production environment as getting the packages away from the development -system's build directory prevents accidental overwrites. - -A simple build that targets just one device produces more than one -package database. In other words, the packages produced by a build are -separated out into a couple of different package groupings based on -criteria such as the target's CPU architecture, the target board, or the -C library used on the target. For example, a build targeting the -``qemux86`` device produces the following three package databases: -``noarch``, ``i586``, and ``qemux86``. If you wanted your ``qemux86`` -device to be aware of all the packages that were available to it, you -would need to point it to each of these databases individually. In a -similar way, a traditional Linux distribution usually is configured to -be aware of a number of software repositories from which it retrieves -packages. - -Using runtime package management is completely optional and not required -for a successful build or deployment in any way. But if you want to make -use of runtime package management, you need to do a couple things above -and beyond the basics. The remainder of this section describes what you -need to do. - -Build Considerations -~~~~~~~~~~~~~~~~~~~~ - -This section describes build considerations of which you need to be -aware in order to provide support for runtime package management. - -When BitBake generates packages, it needs to know what format or formats -to use. In your configuration, you use the -:term:`PACKAGE_CLASSES` -variable to specify the format: - -1. Open the ``local.conf`` file inside your - :term:`Build Directory` (e.g. - ``poky/build/conf/local.conf``). - -2. Select the desired package format as follows:: - - PACKAGE_CLASSES ?= "package_packageformat" - - where packageformat can be "ipk", "rpm", - "deb", or "tar" which are the supported package formats. - - .. note:: - - Because the Yocto Project supports four different package formats, - you can set the variable with more than one argument. However, the - OpenEmbedded build system only uses the first argument when - creating an image or Software Development Kit (SDK). - -If you would like your image to start off with a basic package database -containing the packages in your current build as well as to have the -relevant tools available on the target for runtime package management, -you can include "package-management" in the -:term:`IMAGE_FEATURES` -variable. Including "package-management" in this configuration variable -ensures that when the image is assembled for your target, the image -includes the currently-known package databases as well as the -target-specific tools required for runtime package management to be -performed on the target. However, this is not strictly necessary. You -could start your image off without any databases but only include the -required on-target package tool(s). As an example, you could include -"opkg" in your -:term:`IMAGE_INSTALL` variable -if you are using the IPK package format. You can then initialize your -target's package database(s) later once your image is up and running. - -Whenever you perform any sort of build step that can potentially -generate a package or modify existing package, it is always a good idea -to re-generate the package index after the build by using the following -command:: - - $ bitbake package-index - -It might be tempting to build the -package and the package index at the same time with a command such as -the following:: - - $ bitbake some-package package-index - -Do not do this as -BitBake does not schedule the package index for after the completion of -the package you are building. Consequently, you cannot be sure of the -package index including information for the package you just built. -Thus, be sure to run the package update step separately after building -any packages. - -You can use the -:term:`PACKAGE_FEED_ARCHS`, -:term:`PACKAGE_FEED_BASE_PATHS`, -and -:term:`PACKAGE_FEED_URIS` -variables to pre-configure target images to use a package feed. If you -do not define these variables, then manual steps as described in the -subsequent sections are necessary to configure the target. You should -set these variables before building the image in order to produce a -correctly configured image. - -When your build is complete, your packages reside in the -``${TMPDIR}/deploy/packageformat`` directory. For example, if -``${``\ :term:`TMPDIR`\ ``}`` is -``tmp`` and your selected package type is RPM, then your RPM packages -are available in ``tmp/deploy/rpm``. - -Host or Server Machine Setup -~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Although other protocols are possible, a server using HTTP typically -serves packages. If you want to use HTTP, then set up and configure a -web server such as Apache 2, lighttpd, or Python web server on the -machine serving the packages. - -To keep things simple, this section describes how to set up a -Python web server to share package feeds from the developer's -machine. Although this server might not be the best for a production -environment, the setup is simple and straight forward. Should you want -to use a different server more suited for production (e.g. Apache 2, -Lighttpd, or Nginx), take the appropriate steps to do so. - -From within the build directory where you have built an image based on -your packaging choice (i.e. the -:term:`PACKAGE_CLASSES` -setting), simply start the server. The following example assumes a build -directory of ``poky/build/tmp/deploy/rpm`` and a :term:`PACKAGE_CLASSES` -setting of "package_rpm":: - - $ cd poky/build/tmp/deploy/rpm - $ python3 -m http.server - -Target Setup -~~~~~~~~~~~~ - -Setting up the target differs depending on the package management -system. This section provides information for RPM, IPK, and DEB. - -Using RPM -^^^^^^^^^ - -The `Dandified Packaging -Tool `__ (DNF) performs -runtime package management of RPM packages. In order to use DNF for -runtime package management, you must perform an initial setup on the -target machine for cases where the ``PACKAGE_FEED_*`` variables were not -set as part of the image that is running on the target. This means if -you built your image and did not use these variables as part of the -build and your image is now running on the target, you need to perform -the steps in this section if you want to use runtime package management. - -.. note:: - - For information on the ``PACKAGE_FEED_*`` variables, see - :term:`PACKAGE_FEED_ARCHS`, :term:`PACKAGE_FEED_BASE_PATHS`, and - :term:`PACKAGE_FEED_URIS` in the Yocto Project Reference Manual variables - glossary. - -On the target, you must inform DNF that package databases are available. -You do this by creating a file named -``/etc/yum.repos.d/oe-packages.repo`` and defining the ``oe-packages``. - -As an example, assume the target is able to use the following package -databases: ``all``, ``i586``, and ``qemux86`` from a server named -``my.server``. The specifics for setting up the web server are up to -you. The critical requirement is that the URIs in the target repository -configuration point to the correct remote location for the feeds. - -.. note:: - - For development purposes, you can point the web server to the build - system's ``deploy`` directory. However, for production use, it is better to - copy the package directories to a location outside of the build area and use - that location. Doing so avoids situations where the build system - overwrites or changes the ``deploy`` directory. - -When telling DNF where to look for the package databases, you must -declare individual locations per architecture or a single location used -for all architectures. You cannot do both: - -- *Create an Explicit List of Architectures:* Define individual base - URLs to identify where each package database is located: - - .. code-block:: none - - [oe-packages] - baseurl=http://my.server/rpm/i586 http://my.server/rpm/qemux86 http://my.server/rpm/all - - This example - informs DNF about individual package databases for all three - architectures. - -- *Create a Single (Full) Package Index:* Define a single base URL that - identifies where a full package database is located:: - - [oe-packages] - baseurl=http://my.server/rpm - - This example informs DNF about a single - package database that contains all the package index information for - all supported architectures. - -Once you have informed DNF where to find the package databases, you need -to fetch them: - -.. code-block:: none - - # dnf makecache - -DNF is now able to find, install, and -upgrade packages from the specified repository or repositories. - -.. note:: - - See the `DNF documentation `__ for - additional information. - -Using IPK -^^^^^^^^^ - -The ``opkg`` application performs runtime package management of IPK -packages. You must perform an initial setup for ``opkg`` on the target -machine if the -:term:`PACKAGE_FEED_ARCHS`, -:term:`PACKAGE_FEED_BASE_PATHS`, -and -:term:`PACKAGE_FEED_URIS` -variables have not been set or the target image was built before the -variables were set. - -The ``opkg`` application uses configuration files to find available -package databases. Thus, you need to create a configuration file inside -the ``/etc/opkg/`` directory, which informs ``opkg`` of any repository -you want to use. - -As an example, suppose you are serving packages from a ``ipk/`` -directory containing the ``i586``, ``all``, and ``qemux86`` databases -through an HTTP server named ``my.server``. On the target, create a -configuration file (e.g. ``my_repo.conf``) inside the ``/etc/opkg/`` -directory containing the following: - -.. code-block:: none - - src/gz all http://my.server/ipk/all - src/gz i586 http://my.server/ipk/i586 - src/gz qemux86 http://my.server/ipk/qemux86 - -Next, instruct ``opkg`` to fetch the -repository information: - -.. code-block:: none - - # opkg update - -The ``opkg`` application is now able to find, install, and upgrade packages -from the specified repository. - -Using DEB -^^^^^^^^^ - -The ``apt`` application performs runtime package management of DEB -packages. This application uses a source list file to find available -package databases. You must perform an initial setup for ``apt`` on the -target machine if the -:term:`PACKAGE_FEED_ARCHS`, -:term:`PACKAGE_FEED_BASE_PATHS`, -and -:term:`PACKAGE_FEED_URIS` -variables have not been set or the target image was built before the -variables were set. - -To inform ``apt`` of the repository you want to use, you might create a -list file (e.g. ``my_repo.list``) inside the -``/etc/apt/sources.list.d/`` directory. As an example, suppose you are -serving packages from a ``deb/`` directory containing the ``i586``, -``all``, and ``qemux86`` databases through an HTTP server named -``my.server``. The list file should contain: - -.. code-block:: none - - deb http://my.server/deb/all ./ - deb http://my.server/deb/i586 ./ - deb http://my.server/deb/qemux86 ./ - -Next, instruct the ``apt`` application -to fetch the repository information: - -.. code-block:: none - - $ sudo apt update - -After this step, -``apt`` is able to find, install, and upgrade packages from the -specified repository. - -Generating and Using Signed Packages ------------------------------------- - -In order to add security to RPM packages used during a build, you can -take steps to securely sign them. Once a signature is verified, the -OpenEmbedded build system can use the package in the build. If security -fails for a signed package, the build system stops the build. - -This section describes how to sign RPM packages during a build and how -to use signed package feeds (repositories) when doing a build. - -Signing RPM Packages -~~~~~~~~~~~~~~~~~~~~ - -To enable signing RPM packages, you must set up the following -configurations in either your ``local.config`` or ``distro.config`` -file:: - - # Inherit sign_rpm.bbclass to enable signing functionality - INHERIT += " sign_rpm" - # Define the GPG key that will be used for signing. - RPM_GPG_NAME = "key_name" - # Provide passphrase for the key - RPM_GPG_PASSPHRASE = "passphrase" - -.. note:: - - Be sure to supply appropriate values for both `key_name` and - `passphrase`. - -Aside from the ``RPM_GPG_NAME`` and ``RPM_GPG_PASSPHRASE`` variables in -the previous example, two optional variables related to signing are available: - -- *GPG_BIN:* Specifies a ``gpg`` binary/wrapper that is executed - when the package is signed. - -- *GPG_PATH:* Specifies the ``gpg`` home directory used when the - package is signed. - -Processing Package Feeds -~~~~~~~~~~~~~~~~~~~~~~~~ - -In addition to being able to sign RPM packages, you can also enable -signed package feeds for IPK and RPM packages. - -The steps you need to take to enable signed package feed use are similar -to the steps used to sign RPM packages. You must define the following in -your ``local.config`` or ``distro.config`` file:: - - INHERIT += "sign_package_feed" - PACKAGE_FEED_GPG_NAME = "key_name" - PACKAGE_FEED_GPG_PASSPHRASE_FILE = "path_to_file_containing_passphrase" - -For signed package feeds, the passphrase must be specified in a separate file, -which is pointed to by the ``PACKAGE_FEED_GPG_PASSPHRASE_FILE`` -variable. Regarding security, keeping a plain text passphrase out of the -configuration is more secure. - -Aside from the ``PACKAGE_FEED_GPG_NAME`` and -``PACKAGE_FEED_GPG_PASSPHRASE_FILE`` variables, three optional variables -related to signed package feeds are available: - -- *GPG_BIN* Specifies a ``gpg`` binary/wrapper that is executed - when the package is signed. - -- *GPG_PATH:* Specifies the ``gpg`` home directory used when the - package is signed. - -- *PACKAGE_FEED_GPG_SIGNATURE_TYPE:* Specifies the type of ``gpg`` - signature. This variable applies only to RPM and IPK package feeds. - Allowable values for the ``PACKAGE_FEED_GPG_SIGNATURE_TYPE`` are - "ASC", which is the default and specifies ascii armored, and "BIN", - which specifies binary. - -Testing Packages With ptest ---------------------------- - -A Package Test (ptest) runs tests against packages built by the -OpenEmbedded build system on the target machine. A ptest contains at -least two items: the actual test, and a shell script (``run-ptest``) -that starts the test. The shell script that starts the test must not -contain the actual test - the script only starts the test. On the other -hand, the test can be anything from a simple shell script that runs a -binary and checks the output to an elaborate system of test binaries and -data files. - -The test generates output in the format used by Automake:: - - result: testname - -where the result can be ``PASS``, ``FAIL``, or ``SKIP``, and -the testname can be any identifying string. - -For a list of Yocto Project recipes that are already enabled with ptest, -see the :yocto_wiki:`Ptest ` wiki page. - -.. note:: - - A recipe is "ptest-enabled" if it inherits the - :ref:`ptest ` class. - -Adding ptest to Your Build -~~~~~~~~~~~~~~~~~~~~~~~~~~ - -To add package testing to your build, add the -:term:`DISTRO_FEATURES` and -:term:`EXTRA_IMAGE_FEATURES` -variables to your ``local.conf`` file, which is found in the -:term:`Build Directory`:: - - DISTRO_FEATURES:append = " ptest" - EXTRA_IMAGE_FEATURES += "ptest-pkgs" - -Once your build is complete, the ptest files are installed into the -``/usr/lib/package/ptest`` directory within the image, where ``package`` -is the name of the package. - -Running ptest -~~~~~~~~~~~~~ - -The ``ptest-runner`` package installs a shell script that loops through -all installed ptest test suites and runs them in sequence. Consequently, -you might want to add this package to your image. - -Getting Your Package Ready -~~~~~~~~~~~~~~~~~~~~~~~~~~ - -In order to enable a recipe to run installed ptests on target hardware, -you need to prepare the recipes that build the packages you want to -test. Here is what you have to do for each recipe: - -- *Be sure the recipe inherits - the* :ref:`ptest ` *class:* - Include the following line in each recipe:: - - inherit ptest - -- *Create run-ptest:* This script starts your test. Locate the - script where you will refer to it using - :term:`SRC_URI`. Here is an - example that starts a test for ``dbus``:: - - #!/bin/sh - cd test - make -k runtest-TESTS - -- *Ensure dependencies are met:* If the test adds build or runtime - dependencies that normally do not exist for the package (such as - requiring "make" to run the test suite), use the - :term:`DEPENDS` and - :term:`RDEPENDS` variables in - your recipe in order for the package to meet the dependencies. Here - is an example where the package has a runtime dependency on "make":: - - RDEPENDS:${PN}-ptest += "make" - -- *Add a function to build the test suite:* Not many packages support - cross-compilation of their test suites. Consequently, you usually - need to add a cross-compilation function to the package. - - Many packages based on Automake compile and run the test suite by - using a single command such as ``make check``. However, the host - ``make check`` builds and runs on the same computer, while - cross-compiling requires that the package is built on the host but - executed for the target architecture (though often, as in the case - for ptest, the execution occurs on the host). The built version of - Automake that ships with the Yocto Project includes a patch that - separates building and execution. Consequently, packages that use the - unaltered, patched version of ``make check`` automatically - cross-compiles. - - Regardless, you still must add a ``do_compile_ptest`` function to - build the test suite. Add a function similar to the following to your - recipe:: - - do_compile_ptest() { - oe_runmake buildtest-TESTS - } - -- *Ensure special configurations are set:* If the package requires - special configurations prior to compiling the test code, you must - insert a ``do_configure_ptest`` function into the recipe. - -- *Install the test suite:* The ``ptest`` class automatically copies - the file ``run-ptest`` to the target and then runs make - ``install-ptest`` to run the tests. If this is not enough, you need - to create a ``do_install_ptest`` function and make sure it gets - called after the "make install-ptest" completes. - -Creating Node Package Manager (NPM) Packages --------------------------------------------- - -`NPM `__ is a package -manager for the JavaScript programming language. The Yocto Project -supports the NPM :ref:`fetcher `. You can -use this fetcher in combination with -:doc:`devtool ` to create -recipes that produce NPM packages. - -There are two workflows that allow you to create NPM packages using -``devtool``: the NPM registry modules method and the NPM project code -method. - -.. note:: - - While it is possible to create NPM recipes manually, using - ``devtool`` is far simpler. - -Additionally, some requirements and caveats exist. - -Requirements and Caveats -~~~~~~~~~~~~~~~~~~~~~~~~ - -You need to be aware of the following before using ``devtool`` to create -NPM packages: - -- Of the two methods that you can use ``devtool`` to create NPM - packages, the registry approach is slightly simpler. However, you - might consider the project approach because you do not have to - publish your module in the NPM registry - (`npm-registry `_), which - is NPM's public registry. - -- Be familiar with - :doc:`devtool `. - -- The NPM host tools need the native ``nodejs-npm`` package, which is - part of the OpenEmbedded environment. You need to get the package by - cloning the https://github.com/openembedded/meta-openembedded - repository out of GitHub. Be sure to add the path to your local copy - to your ``bblayers.conf`` file. - -- ``devtool`` cannot detect native libraries in module dependencies. - Consequently, you must manually add packages to your recipe. - -- While deploying NPM packages, ``devtool`` cannot determine which - dependent packages are missing on the target (e.g. the node runtime - ``nodejs``). Consequently, you need to find out what files are - missing and be sure they are on the target. - -- Although you might not need NPM to run your node package, it is - useful to have NPM on your target. The NPM package name is - ``nodejs-npm``. - -Using the Registry Modules Method -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -This section presents an example that uses the ``cute-files`` module, -which is a file browser web application. - -.. note:: - - You must know the ``cute-files`` module version. - -The first thing you need to do is use ``devtool`` and the NPM fetcher to -create the recipe:: - - $ devtool add "npm://registry.npmjs.org;package=cute-files;version=1.0.2" - -The -``devtool add`` command runs ``recipetool create`` and uses the same -fetch URI to download each dependency and capture license details where -possible. The result is a generated recipe. - -The recipe file is fairly simple and contains every license that -``recipetool`` finds and includes the licenses in the recipe's -:term:`LIC_FILES_CHKSUM` -variables. You need to examine the variables and look for those with -"unknown" in the :term:`LICENSE` -field. You need to track down the license information for "unknown" -modules and manually add the information to the recipe. - -``recipetool`` creates a "shrinkwrap" file for your recipe. Shrinkwrap -files capture the version of all dependent modules. Many packages do not -provide shrinkwrap files. ``recipetool`` create a shrinkwrap file as it -runs. - -.. note:: - - A package is created for each sub-module. This policy is the only - practical way to have the licenses for all of the dependencies - represented in the license manifest of the image. - -The ``devtool edit-recipe`` command lets you take a look at the recipe:: - - $ devtool edit-recipe cute-files - SUMMARY = "Turn any folder on your computer into a cute file browser, available on the local network." - LICENSE = "MIT & ISC & Unknown" - LIC_FILES_CHKSUM = "file://LICENSE;md5=71d98c0a1db42956787b1909c74a86ca \ - file://node_modules/toidentifier/LICENSE;md5=1a261071a044d02eb6f2bb47f51a3502 \ - file://node_modules/debug/LICENSE;md5=ddd815a475e7338b0be7a14d8ee35a99 \ - ... - SRC_URI = " \ - npm://registry.npmjs.org/;package=cute-files;version=${PV} \ - npmsw://${THISDIR}/${BPN}/npm-shrinkwrap.json \ - " - S = "${WORKDIR}/npm" - inherit npm - LICENSE:${PN} = "MIT" - LICENSE:${PN}-accepts = "MIT" - LICENSE:${PN}-array-flatten = "MIT" - ... - LICENSE:${PN}-vary = "MIT" - -Here are three key points in the previous example: - -- :term:`SRC_URI` uses the NPM - scheme so that the NPM fetcher is used. - -- ``recipetool`` collects all the license information. If a - sub-module's license is unavailable, the sub-module's name appears in - the comments. - -- The ``inherit npm`` statement causes the - :ref:`npm ` class to package - up all the modules. - -You can run the following command to build the ``cute-files`` package:: - - $ devtool build cute-files - -Remember that ``nodejs`` must be installed on -the target before your package. - -Assuming 192.168.7.2 for the target's IP address, use the following -command to deploy your package:: - - $ devtool deploy-target -s cute-files root@192.168.7.2 - -Once the package is installed on the target, you can -test the application: - -.. note:: - - Because of a known issue, you cannot simply run ``cute-files`` as you would - if you had run ``npm install``. - -:: - - $ cd /usr/lib/node_modules/cute-files - $ node cute-files.js - -On a browser, -go to ``http://192.168.7.2:3000`` and you see the following: - -.. image:: figures/cute-files-npm-example.png - :align: center - -You can find the recipe in ``workspace/recipes/cute-files``. You can use -the recipe in any layer you choose. - -Using the NPM Projects Code Method -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Although it is useful to package modules already in the NPM registry, -adding ``node.js`` projects under development is a more common developer -use case. - -This section covers the NPM projects code method, which is very similar -to the "registry" approach described in the previous section. In the NPM -projects method, you provide ``devtool`` with an URL that points to the -source files. - -Replicating the same example, (i.e. ``cute-files``) use the following -command:: - - $ devtool add https://github.com/martinaglv/cute-files.git - -The -recipe this command generates is very similar to the recipe created in -the previous section. However, the :term:`SRC_URI` looks like the following:: - - SRC_URI = " \ - git://github.com/martinaglv/cute-files.git;protocol=https \ - npmsw://${THISDIR}/${BPN}/npm-shrinkwrap.json \ - " - -In this example, -the main module is taken from the Git repository and dependencies are -taken from the NPM registry. Other than those differences, the recipe is -basically the same between the two methods. You can build and deploy the -package exactly as described in the previous section that uses the -registry modules method. - -Adding custom metadata to packages ----------------------------------- - -The variable -:term:`PACKAGE_ADD_METADATA` -can be used to add additional metadata to packages. This is reflected in -the package control/spec file. To take the ipk format for example, the -CONTROL file stored inside would contain the additional metadata as -additional lines. - -The variable can be used in multiple ways, including using suffixes to -set it for a specific package type and/or package. Note that the order -of precedence is the same as this list: - -- ``PACKAGE_ADD_METADATA_:`` - -- ``PACKAGE_ADD_METADATA_`` - -- ``PACKAGE_ADD_METADATA:`` - -- :term:`PACKAGE_ADD_METADATA` - -`` is a parameter and expected to be a distinct name of specific -package type: - -- IPK for .ipk packages - -- DEB for .deb packages - -- RPM for .rpm packages - -`` is a parameter and expected to be a package name. - -The variable can contain multiple [one-line] metadata fields separated -by the literal sequence '\\n'. The separator can be redefined using the -variable flag ``separator``. - -Here is an example that adds two custom fields for ipk -packages:: - - PACKAGE_ADD_METADATA_IPK = "Vendor: CustomIpk\nGroup:Applications/Spreadsheets" - -Efficiently Fetching Source Files During a Build -================================================ - -The OpenEmbedded build system works with source files located through -the :term:`SRC_URI` variable. When -you build something using BitBake, a big part of the operation is -locating and downloading all the source tarballs. For images, -downloading all the source for various packages can take a significant -amount of time. - -This section shows you how you can use mirrors to speed up fetching -source files and how you can pre-fetch files all of which leads to more -efficient use of resources and time. - -Setting up Effective Mirrors ----------------------------- - -A good deal that goes into a Yocto Project build is simply downloading -all of the source tarballs. Maybe you have been working with another -build system for which you have built up a -sizable directory of source tarballs. Or, perhaps someone else has such -a directory for which you have read access. If so, you can save time by -adding statements to your configuration file so that the build process -checks local directories first for existing tarballs before checking the -Internet. - -Here is an efficient way to set it up in your ``local.conf`` file:: - - SOURCE_MIRROR_URL ?= "file:///home/you/your-download-dir/" - INHERIT += "own-mirrors" - BB_GENERATE_MIRROR_TARBALLS = "1" - # BB_NO_NETWORK = "1" - -In the previous example, the -:term:`BB_GENERATE_MIRROR_TARBALLS` -variable causes the OpenEmbedded build system to generate tarballs of -the Git repositories and store them in the -:term:`DL_DIR` directory. Due to -performance reasons, generating and storing these tarballs is not the -build system's default behavior. - -You can also use the -:term:`PREMIRRORS` variable. For -an example, see the variable's glossary entry in the Yocto Project -Reference Manual. - -Getting Source Files and Suppressing the Build ----------------------------------------------- - -Another technique you can use to ready yourself for a successive string -of build operations, is to pre-fetch all the source files without -actually starting a build. This technique lets you work through any -download issues and ultimately gathers all the source files into your -download directory :ref:`structure-build-downloads`, -which is located with :term:`DL_DIR`. - -Use the following BitBake command form to fetch all the necessary -sources without starting the build:: - - $ bitbake target --runall=fetch - -This -variation of the BitBake command guarantees that you have all the -sources for that BitBake target should you disconnect from the Internet -and want to do the build later offline. - -Selecting an Initialization Manager -=================================== - -By default, the Yocto Project uses SysVinit as the initialization -manager. However, there is also support for systemd, which is a full -replacement for init with parallel starting of services, reduced shell -overhead and other features that are used by many distributions. - -Within the system, SysVinit treats system components as services. These -services are maintained as shell scripts stored in the ``/etc/init.d/`` -directory. Services organize into different run levels. This -organization is maintained by putting links to the services in the -``/etc/rcN.d/`` directories, where `N/` is one of the following options: -"S", "0", "1", "2", "3", "4", "5", or "6". - -.. note:: - - Each runlevel has a dependency on the previous runlevel. This - dependency allows the services to work properly. - -In comparison, systemd treats components as units. Using units is a -broader concept as compared to using a service. A unit includes several -different types of entities. Service is one of the types of entities. -The runlevel concept in SysVinit corresponds to the concept of a target -in systemd, where target is also a type of supported unit. - -In a SysVinit-based system, services load sequentially (i.e. one by one) -during init and parallelization is not supported. With systemd, services -start in parallel. Needless to say, the method can have an impact on -system startup performance. - -If you want to use SysVinit, you do not have to do anything. But, if you -want to use systemd, you must take some steps as described in the -following sections. - -Using systemd Exclusively -------------------------- - -Set these variables in your distribution configuration file as follows:: - - DISTRO_FEATURES:append = " systemd" - VIRTUAL-RUNTIME_init_manager = "systemd" - -You can also prevent the SysVinit distribution feature from -being automatically enabled as follows:: - - DISTRO_FEATURES_BACKFILL_CONSIDERED = "sysvinit" - -Doing so removes any -redundant SysVinit scripts. - -To remove initscripts from your image altogether, set this variable -also:: - - VIRTUAL-RUNTIME_initscripts = "" - -For information on the backfill variable, see -:term:`DISTRO_FEATURES_BACKFILL_CONSIDERED`. - -Using systemd for the Main Image and Using SysVinit for the Rescue Image ------------------------------------------------------------------------- - -Set these variables in your distribution configuration file as follows:: - - DISTRO_FEATURES:append = " systemd" - VIRTUAL-RUNTIME_init_manager = "systemd" - -Doing so causes your main image to use the -``packagegroup-core-boot.bb`` recipe and systemd. The rescue/minimal -image cannot use this package group. However, it can install SysVinit -and the appropriate packages will have support for both systemd and -SysVinit. - -Using systemd-journald without a traditional syslog daemon ----------------------------------------------------------- - -Counter-intuitively, ``systemd-journald`` is not a syslog runtime or provider, -and the proper way to use systemd-journald as your sole logging mechanism is to -effectively disable syslog entirely by setting these variables in your distribution -configuration file:: - - VIRTUAL-RUNTIME_syslog = "" - VIRTUAL-RUNTIME_base-utils-syslog = "" - -Doing so will prevent ``rsyslog`` / ``busybox-syslog`` from being pulled in by -default, leaving only ``journald``. - -Selecting a Device Manager -========================== - -The Yocto Project provides multiple ways to manage the device manager -(``/dev``): - -- Persistent and Pre-Populated ``/dev``: For this case, the ``/dev`` - directory is persistent and the required device nodes are created - during the build. - -- Use ``devtmpfs`` with a Device Manager: For this case, the ``/dev`` - directory is provided by the kernel as an in-memory file system and - is automatically populated by the kernel at runtime. Additional - configuration of device nodes is done in user space by a device - manager like ``udev`` or ``busybox-mdev``. - -Using Persistent and Pre-Populated ``/dev`` --------------------------------------------- - -To use the static method for device population, you need to set the -:term:`USE_DEVFS` variable to "0" -as follows:: - - USE_DEVFS = "0" - -The content of the resulting ``/dev`` directory is defined in a Device -Table file. The -:term:`IMAGE_DEVICE_TABLES` -variable defines the Device Table to use and should be set in the -machine or distro configuration file. Alternatively, you can set this -variable in your ``local.conf`` configuration file. - -If you do not define the :term:`IMAGE_DEVICE_TABLES` variable, the default -``device_table-minimal.txt`` is used:: - - IMAGE_DEVICE_TABLES = "device_table-mymachine.txt" - -The population is handled by the ``makedevs`` utility during image -creation: - -Using ``devtmpfs`` and a Device Manager ---------------------------------------- - -To use the dynamic method for device population, you need to use (or be -sure to set) the :term:`USE_DEVFS` -variable to "1", which is the default:: - - USE_DEVFS = "1" - -With this -setting, the resulting ``/dev`` directory is populated by the kernel -using ``devtmpfs``. Make sure the corresponding kernel configuration -variable ``CONFIG_DEVTMPFS`` is set when building you build a Linux -kernel. - -All devices created by ``devtmpfs`` will be owned by ``root`` and have -permissions ``0600``. - -To have more control over the device nodes, you can use a device manager -like ``udev`` or ``busybox-mdev``. You choose the device manager by -defining the ``VIRTUAL-RUNTIME_dev_manager`` variable in your machine or -distro configuration file. Alternatively, you can set this variable in -your ``local.conf`` configuration file:: - - VIRTUAL-RUNTIME_dev_manager = "udev" - - # Some alternative values - # VIRTUAL-RUNTIME_dev_manager = "busybox-mdev" - # VIRTUAL-RUNTIME_dev_manager = "systemd" - -Using an External SCM -===================== - -If you're working on a recipe that pulls from an external Source Code -Manager (SCM), it is possible to have the OpenEmbedded build system -notice new recipe changes added to the SCM and then build the resulting -packages that depend on the new recipes by using the latest versions. -This only works for SCMs from which it is possible to get a sensible -revision number for changes. Currently, you can do this with Apache -Subversion (SVN), Git, and Bazaar (BZR) repositories. - -To enable this behavior, the :term:`PV` of -the recipe needs to reference -:term:`SRCPV`. Here is an example:: - - PV = "1.2.3+git${SRCPV}" - -Then, you can add the following to your -``local.conf``:: - - SRCREV:pn-PN = "${AUTOREV}" - -:term:`PN` is the name of the recipe for -which you want to enable automatic source revision updating. - -If you do not want to update your local configuration file, you can add -the following directly to the recipe to finish enabling the feature:: - - SRCREV = "${AUTOREV}" - -The Yocto Project provides a distribution named ``poky-bleeding``, whose -configuration file contains the line:: - - require conf/distro/include/poky-floating-revisions.inc - -This line pulls in the -listed include file that contains numerous lines of exactly that form:: - - #SRCREV:pn-opkg-native ?= "${AUTOREV}" - #SRCREV:pn-opkg-sdk ?= "${AUTOREV}" - #SRCREV:pn-opkg ?= "${AUTOREV}" - #SRCREV:pn-opkg-utils-native ?= "${AUTOREV}" - #SRCREV:pn-opkg-utils ?= "${AUTOREV}" - SRCREV:pn-gconf-dbus ?= "${AUTOREV}" - SRCREV:pn-matchbox-common ?= "${AUTOREV}" - SRCREV:pn-matchbox-config-gtk ?= "${AUTOREV}" - SRCREV:pn-matchbox-desktop ?= "${AUTOREV}" - SRCREV:pn-matchbox-keyboard ?= "${AUTOREV}" - SRCREV:pn-matchbox-panel-2 ?= "${AUTOREV}" - SRCREV:pn-matchbox-themes-extra ?= "${AUTOREV}" - SRCREV:pn-matchbox-terminal ?= "${AUTOREV}" - SRCREV:pn-matchbox-wm ?= "${AUTOREV}" - SRCREV:pn-settings-daemon ?= "${AUTOREV}" - SRCREV:pn-screenshot ?= "${AUTOREV}" - . . . - -These lines allow you to -experiment with building a distribution that tracks the latest -development source for numerous packages. - -.. note:: - - The ``poky-bleeding`` distribution is not tested on a regular basis. Keep - this in mind if you use it. - -Creating a Read-Only Root Filesystem -==================================== - -Suppose, for security reasons, you need to disable your target device's -root filesystem's write permissions (i.e. you need a read-only root -filesystem). Or, perhaps you are running the device's operating system -from a read-only storage device. For either case, you can customize your -image for that behavior. - -.. note:: - - Supporting a read-only root filesystem requires that the system and - applications do not try to write to the root filesystem. You must - configure all parts of the target system to write elsewhere, or to - gracefully fail in the event of attempting to write to the root - filesystem. - -Creating the Root Filesystem ----------------------------- - -To create the read-only root filesystem, simply add the -"read-only-rootfs" feature to your image, normally in one of two ways. -The first way is to add the "read-only-rootfs" image feature in the -image's recipe file via the :term:`IMAGE_FEATURES` variable:: - - IMAGE_FEATURES += "read-only-rootfs" - -As an alternative, you can add the same feature -from within your build directory's ``local.conf`` file with the -associated :term:`EXTRA_IMAGE_FEATURES` variable, as in:: - - EXTRA_IMAGE_FEATURES = "read-only-rootfs" - -For more information on how to use these variables, see the -":ref:`dev-manual/common-tasks:Customizing Images Using Custom \`\`IMAGE_FEATURES\`\` and \`\`EXTRA_IMAGE_FEATURES\`\``" -section. For information on the variables, see -:term:`IMAGE_FEATURES` and -:term:`EXTRA_IMAGE_FEATURES`. - -Post-Installation Scripts and Read-Only Root Filesystem -------------------------------------------------------- - -It is very important that you make sure all post-Installation -(``pkg_postinst``) scripts for packages that are installed into the -image can be run at the time when the root filesystem is created during -the build on the host system. These scripts cannot attempt to run during -the first boot on the target device. With the "read-only-rootfs" feature -enabled, the build system makes sure that all post-installation scripts -succeed at file system creation time. If any of these scripts -still need to be run after the root filesystem is created, the build -immediately fails. These build-time checks ensure that the build fails -rather than the target device fails later during its initial boot -operation. - -Most of the common post-installation scripts generated by the build -system for the out-of-the-box Yocto Project are engineered so that they -can run during root filesystem creation (e.g. post-installation scripts -for caching fonts). However, if you create and add custom scripts, you -need to be sure they can be run during this file system creation. - -Here are some common problems that prevent post-installation scripts -from running during root filesystem creation: - -- *Not using $D in front of absolute paths:* The build system defines - ``$``\ :term:`D` when the root - filesystem is created. Furthermore, ``$D`` is blank when the script - is run on the target device. This implies two purposes for ``$D``: - ensuring paths are valid in both the host and target environments, - and checking to determine which environment is being used as a method - for taking appropriate actions. - -- *Attempting to run processes that are specific to or dependent on the - target architecture:* You can work around these attempts by using - native tools, which run on the host system, to accomplish the same - tasks, or by alternatively running the processes under QEMU, which - has the ``qemu_run_binary`` function. For more information, see the - :ref:`qemu ` class. - -Areas With Write Access ------------------------ - -With the "read-only-rootfs" feature enabled, any attempt by the target -to write to the root filesystem at runtime fails. Consequently, you must -make sure that you configure processes and applications that attempt -these types of writes do so to directories with write access (e.g. -``/tmp`` or ``/var/run``). - -Maintaining Build Output Quality -================================ - -Many factors can influence the quality of a build. For example, if you -upgrade a recipe to use a new version of an upstream software package or -you experiment with some new configuration options, subtle changes can -occur that you might not detect until later. Consider the case where -your recipe is using a newer version of an upstream package. In this -case, a new version of a piece of software might introduce an optional -dependency on another library, which is auto-detected. If that library -has already been built when the software is building, the software will -link to the built library and that library will be pulled into your -image along with the new software even if you did not want the library. - -The :ref:`buildhistory ` -class helps you maintain the quality of your build output. You -can use the class to highlight unexpected and possibly unwanted changes -in the build output. When you enable build history, it records -information about the contents of each package and image and then -commits that information to a local Git repository where you can examine -the information. - -The remainder of this section describes the following: - -- :ref:`How you can enable and disable build history ` - -- :ref:`How to understand what the build history contains ` - -- :ref:`How to limit the information used for build history ` - -- :ref:`How to examine the build history from both a command-line and web interface ` - -Enabling and Disabling Build History ------------------------------------- - -Build history is disabled by default. To enable it, add the following -:term:`INHERIT` statement and set the -:term:`BUILDHISTORY_COMMIT` -variable to "1" at the end of your ``conf/local.conf`` file found in the -:term:`Build Directory`:: - - INHERIT += "buildhistory" - BUILDHISTORY_COMMIT = "1" - -Enabling build history as -previously described causes the OpenEmbedded build system to collect -build output information and commit it as a single commit to a local -:ref:`overview-manual/development-environment:git` repository. - -.. note:: - - Enabling build history increases your build times slightly, - particularly for images, and increases the amount of disk space used - during the build. - -You can disable build history by removing the previous statements from -your ``conf/local.conf`` file. - -Understanding What the Build History Contains ---------------------------------------------- - -Build history information is kept in -``${``\ :term:`TOPDIR`\ ``}/buildhistory`` -in the Build Directory as defined by the -:term:`BUILDHISTORY_DIR` -variable. Here is an example abbreviated listing: - -.. image:: figures/buildhistory.png - :align: center - -At the top level, there is a ``metadata-revs`` file that lists the -revisions of the repositories for the enabled layers when the build was -produced. The rest of the data splits into separate ``packages``, -``images`` and ``sdk`` directories, the contents of which are described -as follows. - -Build History Package Information -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The history for each package contains a text file that has name-value -pairs with information about the package. For example, -``buildhistory/packages/i586-poky-linux/busybox/busybox/latest`` -contains the following: - -.. code-block:: none - - PV = 1.22.1 - PR = r32 - RPROVIDES = - RDEPENDS = glibc (>= 2.20) update-alternatives-opkg - RRECOMMENDS = busybox-syslog busybox-udhcpc update-rc.d - PKGSIZE = 540168 - FILES = /usr/bin/* /usr/sbin/* /usr/lib/busybox/* /usr/lib/lib*.so.* \ - /etc /com /var /bin/* /sbin/* /lib/*.so.* /lib/udev/rules.d \ - /usr/lib/udev/rules.d /usr/share/busybox /usr/lib/busybox/* \ - /usr/share/pixmaps /usr/share/applications /usr/share/idl \ - /usr/share/omf /usr/share/sounds /usr/lib/bonobo/servers - FILELIST = /bin/busybox /bin/busybox.nosuid /bin/busybox.suid /bin/sh \ - /etc/busybox.links.nosuid /etc/busybox.links.suid - -Most of these -name-value pairs correspond to variables used to produce the package. -The exceptions are ``FILELIST``, which is the actual list of files in -the package, and ``PKGSIZE``, which is the total size of files in the -package in bytes. - -There is also a file that corresponds to the recipe from which the package -came (e.g. ``buildhistory/packages/i586-poky-linux/busybox/latest``): - -.. code-block:: none - - PV = 1.22.1 - PR = r32 - DEPENDS = initscripts kern-tools-native update-rc.d-native \ - virtual/i586-poky-linux-compilerlibs virtual/i586-poky-linux-gcc \ - virtual/libc virtual/update-alternatives - PACKAGES = busybox-ptest busybox-httpd busybox-udhcpd busybox-udhcpc \ - busybox-syslog busybox-mdev busybox-hwclock busybox-dbg \ - busybox-staticdev busybox-dev busybox-doc busybox-locale busybox - -Finally, for those recipes fetched from a version control system (e.g., -Git), there is a file that lists source revisions that are specified in -the recipe and the actual revisions used during the build. Listed -and actual revisions might differ when -:term:`SRCREV` is set to -${:term:`AUTOREV`}. Here is an -example assuming -``buildhistory/packages/qemux86-poky-linux/linux-yocto/latest_srcrev``):: - - # SRCREV_machine = "38cd560d5022ed2dbd1ab0dca9642e47c98a0aa1" - SRCREV_machine = "38cd560d5022ed2dbd1ab0dca9642e47c98a0aa1" - # SRCREV_meta = "a227f20eff056e511d504b2e490f3774ab260d6f" - SRCREV_meta ="a227f20eff056e511d504b2e490f3774ab260d6f" - -You can use the -``buildhistory-collect-srcrevs`` command with the ``-a`` option to -collect the stored :term:`SRCREV` values from build history and report them -in a format suitable for use in global configuration (e.g., -``local.conf`` or a distro include file) to override floating -:term:`AUTOREV` values to a fixed set of revisions. Here is some example -output from this command:: - - $ buildhistory-collect-srcrevs -a - # all-poky-linux - SRCREV:pn-ca-certificates = "07de54fdcc5806bde549e1edf60738c6bccf50e8" - SRCREV:pn-update-rc.d = "8636cf478d426b568c1be11dbd9346f67e03adac" - # core2-64-poky-linux - SRCREV:pn-binutils = "87d4632d36323091e731eb07b8aa65f90293da66" - SRCREV:pn-btrfs-tools = "8ad326b2f28c044cb6ed9016d7c3285e23b673c8" - SRCREV_bzip2-tests:pn-bzip2 = "f9061c030a25de5b6829e1abf373057309c734c0" - SRCREV:pn-e2fsprogs = "02540dedd3ddc52c6ae8aaa8a95ce75c3f8be1c0" - SRCREV:pn-file = "504206e53a89fd6eed71aeaf878aa3512418eab1" - SRCREV_glibc:pn-glibc = "24962427071fa532c3c48c918e9d64d719cc8a6c" - SRCREV:pn-gnome-desktop-testing = "e346cd4ed2e2102c9b195b614f3c642d23f5f6e7" - SRCREV:pn-init-system-helpers = "dbd9197569c0935029acd5c9b02b84c68fd937ee" - SRCREV:pn-kmod = "b6ecfc916a17eab8f93be5b09f4e4f845aabd3d1" - SRCREV:pn-libnsl2 = "82245c0c58add79a8e34ab0917358217a70e5100" - SRCREV:pn-libseccomp = "57357d2741a3b3d3e8425889a6b79a130e0fa2f3" - SRCREV:pn-libxcrypt = "50cf2b6dd4fdf04309445f2eec8de7051d953abf" - SRCREV:pn-ncurses = "51d0fd9cc3edb975f04224f29f777f8f448e8ced" - SRCREV:pn-procps = "19a508ea121c0c4ac6d0224575a036de745eaaf8" - SRCREV:pn-psmisc = "5fab6b7ab385080f1db725d6803136ec1841a15f" - SRCREV:pn-ptest-runner = "bcb82804daa8f725b6add259dcef2067e61a75aa" - SRCREV:pn-shared-mime-info = "18e558fa1c8b90b86757ade09a4ba4d6a6cf8f70" - SRCREV:pn-zstd = "e47e674cd09583ff0503f0f6defd6d23d8b718d3" - # qemux86_64-poky-linux - SRCREV_machine:pn-linux-yocto = "20301aeb1a64164b72bc72af58802b315e025c9c" - SRCREV_meta:pn-linux-yocto = "2d38a472b21ae343707c8bd64ac68a9eaca066a0" - # x86_64-linux - SRCREV:pn-binutils-cross-x86_64 = "87d4632d36323091e731eb07b8aa65f90293da66" - SRCREV_glibc:pn-cross-localedef-native = "24962427071fa532c3c48c918e9d64d719cc8a6c" - SRCREV_localedef:pn-cross-localedef-native = "794da69788cbf9bf57b59a852f9f11307663fa87" - SRCREV:pn-debianutils-native = "de14223e5bffe15e374a441302c528ffc1cbed57" - SRCREV:pn-libmodulemd-native = "ee80309bc766d781a144e6879419b29f444d94eb" - SRCREV:pn-virglrenderer-native = "363915595e05fb252e70d6514be2f0c0b5ca312b" - SRCREV:pn-zstd-native = "e47e674cd09583ff0503f0f6defd6d23d8b718d3" - -.. note:: - - Here are some notes on using the ``buildhistory-collect-srcrevs`` command: - - - By default, only values where the :term:`SRCREV` was not hardcoded - (usually when :term:`AUTOREV` is used) are reported. Use the ``-a`` - option to see all :term:`SRCREV` values. - - - The output statements might not have any effect if overrides are - applied elsewhere in the build system configuration. Use the - ``-f`` option to add the ``forcevariable`` override to each output - line if you need to work around this restriction. - - - The script does apply special handling when building for multiple - machines. However, the script does place a comment before each set - of values that specifies which triplet to which they belong as - previously shown (e.g., ``i586-poky-linux``). - -Build History Image Information -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The files produced for each image are as follows: - -- ``image-files:`` A directory containing selected files from the root - filesystem. The files are defined by - :term:`BUILDHISTORY_IMAGE_FILES`. - -- ``build-id.txt:`` Human-readable information about the build - configuration and metadata source revisions. This file contains the - full build header as printed by BitBake. - -- ``*.dot:`` Dependency graphs for the image that are compatible with - ``graphviz``. - -- ``files-in-image.txt:`` A list of files in the image with - permissions, owner, group, size, and symlink information. - -- ``image-info.txt:`` A text file containing name-value pairs with - information about the image. See the following listing example for - more information. - -- ``installed-package-names.txt:`` A list of installed packages by name - only. - -- ``installed-package-sizes.txt:`` A list of installed packages ordered - by size. - -- ``installed-packages.txt:`` A list of installed packages with full - package filenames. - -.. note:: - - Installed package information is able to be gathered and produced - even if package management is disabled for the final image. - -Here is an example of ``image-info.txt``: - -.. code-block:: none - - DISTRO = poky - DISTRO_VERSION = 3.4+snapshot-a0245d7be08f3d24ea1875e9f8872aa6bbff93be - USER_CLASSES = buildstats - IMAGE_CLASSES = qemuboot qemuboot license_image - IMAGE_FEATURES = debug-tweaks - IMAGE_LINGUAS = - IMAGE_INSTALL = packagegroup-core-boot speex speexdsp - BAD_RECOMMENDATIONS = - NO_RECOMMENDATIONS = - PACKAGE_EXCLUDE = - ROOTFS_POSTPROCESS_COMMAND = write_package_manifest; license_create_manifest; cve_check_write_rootfs_manifest; ssh_allow_empty_password; ssh_allow_root_login; postinst_enable_logging; rootfs_update_timestamp; write_image_test_data; empty_var_volatile; sort_passwd; rootfs_reproducible; - IMAGE_POSTPROCESS_COMMAND = buildhistory_get_imageinfo ; - IMAGESIZE = 9265 - -Other than ``IMAGESIZE``, -which is the total size of the files in the image in Kbytes, the -name-value pairs are variables that may have influenced the content of -the image. This information is often useful when you are trying to -determine why a change in the package or file listings has occurred. - -Using Build History to Gather Image Information Only -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -As you can see, build history produces image information, including -dependency graphs, so you can see why something was pulled into the -image. If you are just interested in this information and not interested -in collecting specific package or SDK information, you can enable -writing only image information without any history by adding the -following to your ``conf/local.conf`` file found in the -:term:`Build Directory`:: - - INHERIT += "buildhistory" - BUILDHISTORY_COMMIT = "0" - BUILDHISTORY_FEATURES = "image" - -Here, you set the -:term:`BUILDHISTORY_FEATURES` -variable to use the image feature only. - -Build History SDK Information -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Build history collects similar information on the contents of SDKs (e.g. -``bitbake -c populate_sdk imagename``) as compared to information it -collects for images. Furthermore, this information differs depending on -whether an extensible or standard SDK is being produced. - -The following list shows the files produced for SDKs: - -- ``files-in-sdk.txt:`` A list of files in the SDK with permissions, - owner, group, size, and symlink information. This list includes both - the host and target parts of the SDK. - -- ``sdk-info.txt:`` A text file containing name-value pairs with - information about the SDK. See the following listing example for more - information. - -- ``sstate-task-sizes.txt:`` A text file containing name-value pairs - with information about task group sizes (e.g. ``do_populate_sysroot`` - tasks have a total size). The ``sstate-task-sizes.txt`` file exists - only when an extensible SDK is created. - -- ``sstate-package-sizes.txt:`` A text file containing name-value pairs - with information for the shared-state packages and sizes in the SDK. - The ``sstate-package-sizes.txt`` file exists only when an extensible - SDK is created. - -- ``sdk-files:`` A folder that contains copies of the files mentioned - in ``BUILDHISTORY_SDK_FILES`` if the files are present in the output. - Additionally, the default value of ``BUILDHISTORY_SDK_FILES`` is - specific to the extensible SDK although you can set it differently if - you would like to pull in specific files from the standard SDK. - - The default files are ``conf/local.conf``, ``conf/bblayers.conf``, - ``conf/auto.conf``, ``conf/locked-sigs.inc``, and - ``conf/devtool.conf``. Thus, for an extensible SDK, these files get - copied into the ``sdk-files`` directory. - -- The following information appears under each of the ``host`` and - ``target`` directories for the portions of the SDK that run on the - host and on the target, respectively: - - .. note:: - - The following files for the most part are empty when producing an - extensible SDK because this type of SDK is not constructed from - packages as is the standard SDK. - - - ``depends.dot:`` Dependency graph for the SDK that is compatible - with ``graphviz``. - - - ``installed-package-names.txt:`` A list of installed packages by - name only. - - - ``installed-package-sizes.txt:`` A list of installed packages - ordered by size. - - - ``installed-packages.txt:`` A list of installed packages with full - package filenames. - -Here is an example of ``sdk-info.txt``: - -.. code-block:: none - - DISTRO = poky - DISTRO_VERSION = 1.3+snapshot-20130327 - SDK_NAME = poky-glibc-i686-arm - SDK_VERSION = 1.3+snapshot - SDKMACHINE = - SDKIMAGE_FEATURES = dev-pkgs dbg-pkgs - BAD_RECOMMENDATIONS = - SDKSIZE = 352712 - -Other than ``SDKSIZE``, which is -the total size of the files in the SDK in Kbytes, the name-value pairs -are variables that might have influenced the content of the SDK. This -information is often useful when you are trying to determine why a -change in the package or file listings has occurred. - -Examining Build History Information -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -You can examine build history output from the command line or from a web -interface. - -To see any changes that have occurred (assuming you have -:term:`BUILDHISTORY_COMMIT` = "1"), -you can simply use any Git command that allows you to view the history -of a repository. Here is one method:: - - $ git log -p - -You need to realize, -however, that this method does show changes that are not significant -(e.g. a package's size changing by a few bytes). - -There is a command-line tool called ``buildhistory-diff``, though, -that queries the Git repository and prints just the differences that -might be significant in human-readable form. Here is an example:: - - $ poky/poky/scripts/buildhistory-diff . HEAD^ - Changes to images/qemux86_64/glibc/core-image-minimal (files-in-image.txt): - /etc/anotherpkg.conf was added - /sbin/anotherpkg was added - * (installed-package-names.txt): - * anotherpkg was added - Changes to images/qemux86_64/glibc/core-image-minimal (installed-package-names.txt): - anotherpkg was added - packages/qemux86_64-poky-linux/v86d: PACKAGES: added "v86d-extras" - * PR changed from "r0" to "r1" - * PV changed from "0.1.10" to "0.1.12" - packages/qemux86_64-poky-linux/v86d/v86d: PKGSIZE changed from 110579 to 144381 (+30%) - * PR changed from "r0" to "r1" - * PV changed from "0.1.10" to "0.1.12" - -.. note:: - - The ``buildhistory-diff`` tool requires the ``GitPython`` - package. Be sure to install it using Pip3 as follows:: - - $ pip3 install GitPython --user - - - Alternatively, you can install ``python3-git`` using the appropriate - distribution package manager (e.g. ``apt``, ``dnf``, or ``zipper``). - -To see changes to the build history using a web interface, follow the -instruction in the ``README`` file -:yocto_git:`here `. - -Here is a sample screenshot of the interface: - -.. image:: figures/buildhistory-web.png - :align: center - -Performing Automated Runtime Testing -==================================== - -The OpenEmbedded build system makes available a series of automated -tests for images to verify runtime functionality. You can run these -tests on either QEMU or actual target hardware. Tests are written in -Python making use of the ``unittest`` module, and the majority of them -run commands on the target system over SSH. This section describes how -you set up the environment to use these tests, run available tests, and -write and add your own tests. - -For information on the test and QA infrastructure available within the -Yocto Project, see the ":ref:`ref-manual/release-process:testing and quality assurance`" -section in the Yocto Project Reference Manual. - -Enabling Tests --------------- - -Depending on whether you are planning to run tests using QEMU or on the -hardware, you have to take different steps to enable the tests. See the -following subsections for information on how to enable both types of -tests. - -Enabling Runtime Tests on QEMU -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -In order to run tests, you need to do the following: - -- *Set up to avoid interaction with sudo for networking:* To - accomplish this, you must do one of the following: - - - Add ``NOPASSWD`` for your user in ``/etc/sudoers`` either for all - commands or just for ``runqemu-ifup``. You must provide the full - path as that can change if you are using multiple clones of the - source repository. - - .. note:: - - On some distributions, you also need to comment out "Defaults - requiretty" in ``/etc/sudoers``. - - - Manually configure a tap interface for your system. - - - Run as root the script in ``scripts/runqemu-gen-tapdevs``, which - should generate a list of tap devices. This is the option - typically chosen for Autobuilder-type environments. - - .. note:: - - - Be sure to use an absolute path when calling this script - with sudo. - - - The package recipe ``qemu-helper-native`` is required to run - this script. Build the package using the following command:: - - $ bitbake qemu-helper-native - -- *Set the DISPLAY variable:* You need to set this variable so that - you have an X server available (e.g. start ``vncserver`` for a - headless machine). - -- *Be sure your host's firewall accepts incoming connections from - 192.168.7.0/24:* Some of the tests (in particular DNF tests) start an - HTTP server on a random high number port, which is used to serve - files to the target. The DNF module serves - ``${WORKDIR}/oe-rootfs-repo`` so it can run DNF channel commands. - That means your host's firewall must accept incoming connections from - 192.168.7.0/24, which is the default IP range used for tap devices by - ``runqemu``. - -- *Be sure your host has the correct packages installed:* Depending - your host's distribution, you need to have the following packages - installed: - - - Ubuntu and Debian: ``sysstat`` and ``iproute2`` - - - openSUSE: ``sysstat`` and ``iproute2`` - - - Fedora: ``sysstat`` and ``iproute`` - - - CentOS: ``sysstat`` and ``iproute`` - -Once you start running the tests, the following happens: - -1. A copy of the root filesystem is written to ``${WORKDIR}/testimage``. - -2. The image is booted under QEMU using the standard ``runqemu`` script. - -3. A default timeout of 500 seconds occurs to allow for the boot process - to reach the login prompt. You can change the timeout period by - setting - :term:`TEST_QEMUBOOT_TIMEOUT` - in the ``local.conf`` file. - -4. Once the boot process is reached and the login prompt appears, the - tests run. The full boot log is written to - ``${WORKDIR}/testimage/qemu_boot_log``. - -5. Each test module loads in the order found in :term:`TEST_SUITES`. You can - find the full output of the commands run over SSH in - ``${WORKDIR}/testimgage/ssh_target_log``. - -6. If no failures occur, the task running the tests ends successfully. - You can find the output from the ``unittest`` in the task log at - ``${WORKDIR}/temp/log.do_testimage``. - -Enabling Runtime Tests on Hardware -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The OpenEmbedded build system can run tests on real hardware, and for -certain devices it can also deploy the image to be tested onto the -device beforehand. - -For automated deployment, a "controller image" is installed onto the -hardware once as part of setup. Then, each time tests are to be run, the -following occurs: - -1. The controller image is booted into and used to write the image to be - tested to a second partition. - -2. The device is then rebooted using an external script that you need to - provide. - -3. The device boots into the image to be tested. - -When running tests (independent of whether the image has been deployed -automatically or not), the device is expected to be connected to a -network on a pre-determined IP address. You can either use static IP -addresses written into the image, or set the image to use DHCP and have -your DHCP server on the test network assign a known IP address based on -the MAC address of the device. - -In order to run tests on hardware, you need to set :term:`TEST_TARGET` to an -appropriate value. For QEMU, you do not have to change anything, the -default value is "qemu". For running tests on hardware, the following -options are available: - -- *"simpleremote":* Choose "simpleremote" if you are going to run tests - on a target system that is already running the image to be tested and - is available on the network. You can use "simpleremote" in - conjunction with either real hardware or an image running within a - separately started QEMU or any other virtual machine manager. - -- *"SystemdbootTarget":* Choose "SystemdbootTarget" if your hardware is - an EFI-based machine with ``systemd-boot`` as bootloader and - ``core-image-testmaster`` (or something similar) is installed. Also, - your hardware under test must be in a DHCP-enabled network that gives - it the same IP address for each reboot. - - If you choose "SystemdbootTarget", there are additional requirements - and considerations. See the - ":ref:`dev-manual/common-tasks:selecting systemdboottarget`" section, which - follows, for more information. - -- *"BeagleBoneTarget":* Choose "BeagleBoneTarget" if you are deploying - images and running tests on the BeagleBone "Black" or original - "White" hardware. For information on how to use these tests, see the - comments at the top of the BeagleBoneTarget - ``meta-yocto-bsp/lib/oeqa/controllers/beaglebonetarget.py`` file. - -- *"EdgeRouterTarget":* Choose "EdgeRouterTarget" if you are deploying - images and running tests on the Ubiquiti Networks EdgeRouter Lite. - For information on how to use these tests, see the comments at the - top of the EdgeRouterTarget - ``meta-yocto-bsp/lib/oeqa/controllers/edgeroutertarget.py`` file. - -- *"GrubTarget":* Choose "GrubTarget" if you are deploying images and running - tests on any generic PC that boots using GRUB. For information on how - to use these tests, see the comments at the top of the GrubTarget - ``meta-yocto-bsp/lib/oeqa/controllers/grubtarget.py`` file. - -- *"your-target":* Create your own custom target if you want to run - tests when you are deploying images and running tests on a custom - machine within your BSP layer. To do this, you need to add a Python - unit that defines the target class under ``lib/oeqa/controllers/`` - within your layer. You must also provide an empty ``__init__.py``. - For examples, see files in ``meta-yocto-bsp/lib/oeqa/controllers/``. - -Selecting SystemdbootTarget -~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -If you did not set :term:`TEST_TARGET` to "SystemdbootTarget", then you do -not need any information in this section. You can skip down to the -":ref:`dev-manual/common-tasks:running tests`" section. - -If you did set :term:`TEST_TARGET` to "SystemdbootTarget", you also need to -perform a one-time setup of your controller image by doing the following: - -1. *Set EFI_PROVIDER:* Be sure that :term:`EFI_PROVIDER` is as follows:: - - EFI_PROVIDER = "systemd-boot" - -2. *Build the controller image:* Build the ``core-image-testmaster`` image. - The ``core-image-testmaster`` recipe is provided as an example for a - "controller" image and you can customize the image recipe as you would - any other recipe. - - Here are the image recipe requirements: - - - Inherits ``core-image`` so that kernel modules are installed. - - - Installs normal linux utilities not BusyBox ones (e.g. ``bash``, - ``coreutils``, ``tar``, ``gzip``, and ``kmod``). - - - Uses a custom Initial RAM Disk (initramfs) image with a custom - installer. A normal image that you can install usually creates a - single root filesystem partition. This image uses another installer that - creates a specific partition layout. Not all Board Support - Packages (BSPs) can use an installer. For such cases, you need to - manually create the following partition layout on the target: - - - First partition mounted under ``/boot``, labeled "boot". - - - The main root filesystem partition where this image gets installed, - which is mounted under ``/``. - - - Another partition labeled "testrootfs" where test images get - deployed. - -3. *Install image:* Install the image that you just built on the target - system. - -The final thing you need to do when setting :term:`TEST_TARGET` to -"SystemdbootTarget" is to set up the test image: - -1. *Set up your local.conf file:* Make sure you have the following - statements in your ``local.conf`` file:: - - IMAGE_FSTYPES += "tar.gz" - INHERIT += "testimage" - TEST_TARGET = "SystemdbootTarget" - TEST_TARGET_IP = "192.168.2.3" - -2. *Build your test image:* Use BitBake to build the image:: - - $ bitbake core-image-sato - -Power Control -~~~~~~~~~~~~~ - -For most hardware targets other than "simpleremote", you can control -power: - -- You can use :term:`TEST_POWERCONTROL_CMD` together with - :term:`TEST_POWERCONTROL_EXTRA_ARGS` as a command that runs on the host - and does power cycling. The test code passes one argument to that - command: off, on or cycle (off then on). Here is an example that - could appear in your ``local.conf`` file:: - - TEST_POWERCONTROL_CMD = "powercontrol.exp test 10.11.12.1 nuc1" - - In this example, the expect - script does the following: - - .. code-block:: shell - - ssh test@10.11.12.1 "pyctl nuc1 arg" - - It then runs a Python script that controls power for a label called - ``nuc1``. - - .. note:: - - You need to customize :term:`TEST_POWERCONTROL_CMD` and - :term:`TEST_POWERCONTROL_EXTRA_ARGS` for your own setup. The one requirement - is that it accepts "on", "off", and "cycle" as the last argument. - -- When no command is defined, it connects to the device over SSH and - uses the classic reboot command to reboot the device. Classic reboot - is fine as long as the machine actually reboots (i.e. the SSH test - has not failed). It is useful for scenarios where you have a simple - setup, typically with a single board, and where some manual - interaction is okay from time to time. - -If you have no hardware to automatically perform power control but still -wish to experiment with automated hardware testing, you can use the -``dialog-power-control`` script that shows a dialog prompting you to perform -the required power action. This script requires either KDialog or Zenity -to be installed. To use this script, set the -:term:`TEST_POWERCONTROL_CMD` -variable as follows:: - - TEST_POWERCONTROL_CMD = "${COREBASE}/scripts/contrib/dialog-power-control" - -Serial Console Connection -~~~~~~~~~~~~~~~~~~~~~~~~~ - -For test target classes requiring a serial console to interact with the -bootloader (e.g. BeagleBoneTarget, EdgeRouterTarget, and GrubTarget), -you need to specify a command to use to connect to the serial console of -the target machine by using the -:term:`TEST_SERIALCONTROL_CMD` -variable and optionally the -:term:`TEST_SERIALCONTROL_EXTRA_ARGS` -variable. - -These cases could be a serial terminal program if the machine is -connected to a local serial port, or a ``telnet`` or ``ssh`` command -connecting to a remote console server. Regardless of the case, the -command simply needs to connect to the serial console and forward that -connection to standard input and output as any normal terminal program -does. For example, to use the picocom terminal program on serial device -``/dev/ttyUSB0`` at 115200bps, you would set the variable as follows:: - - TEST_SERIALCONTROL_CMD = "picocom /dev/ttyUSB0 -b 115200" - -For local -devices where the serial port device disappears when the device reboots, -an additional "serdevtry" wrapper script is provided. To use this -wrapper, simply prefix the terminal command with -``${COREBASE}/scripts/contrib/serdevtry``:: - - TEST_SERIALCONTROL_CMD = "${COREBASE}/scripts/contrib/serdevtry picocom -b 115200 /dev/ttyUSB0" - -Running Tests -------------- - -You can start the tests automatically or manually: - -- *Automatically running tests:* To run the tests automatically after - the OpenEmbedded build system successfully creates an image, first - set the - :term:`TESTIMAGE_AUTO` - variable to "1" in your ``local.conf`` file in the - :term:`Build Directory`:: - - TESTIMAGE_AUTO = "1" - - Next, build your image. If the image successfully builds, the - tests run:: - - bitbake core-image-sato - -- *Manually running tests:* To manually run the tests, first globally - inherit the - :ref:`testimage ` class - by editing your ``local.conf`` file:: - - INHERIT += "testimage" - - Next, use BitBake to run the tests:: - - bitbake -c testimage image - -All test files reside in ``meta/lib/oeqa/runtime/cases`` in the -:term:`Source Directory`. A test name maps -directly to a Python module. Each test module may contain a number of -individual tests. Tests are usually grouped together by the area tested -(e.g tests for systemd reside in ``meta/lib/oeqa/runtime/cases/systemd.py``). - -You can add tests to any layer provided you place them in the proper -area and you extend :term:`BBPATH` in -the ``local.conf`` file as normal. Be sure that tests reside in -``layer/lib/oeqa/runtime/cases``. - -.. note:: - - Be sure that module names do not collide with module names used in - the default set of test modules in ``meta/lib/oeqa/runtime/cases``. - -You can change the set of tests run by appending or overriding -:term:`TEST_SUITES` variable in -``local.conf``. Each name in :term:`TEST_SUITES` represents a required test -for the image. Test modules named within :term:`TEST_SUITES` cannot be -skipped even if a test is not suitable for an image (e.g. running the -RPM tests on an image without ``rpm``). Appending "auto" to -:term:`TEST_SUITES` causes the build system to try to run all tests that are -suitable for the image (i.e. each test module may elect to skip itself). - -The order you list tests in :term:`TEST_SUITES` is important and influences -test dependencies. Consequently, tests that depend on other tests should -be added after the test on which they depend. For example, since the -``ssh`` test depends on the ``ping`` test, "ssh" needs to come after -"ping" in the list. The test class provides no re-ordering or dependency -handling. - -.. note:: - - Each module can have multiple classes with multiple test methods. - And, Python ``unittest`` rules apply. - -Here are some things to keep in mind when running tests: - -- The default tests for the image are defined as:: - - DEFAULT_TEST_SUITES:pn-image = "ping ssh df connman syslog xorg scp vnc date rpm dnf dmesg" - -- Add your own test to the list of the by using the following:: - - TEST_SUITES:append = " mytest" - -- Run a specific list of tests as follows:: - - TEST_SUITES = "test1 test2 test3" - - Remember, order is important. Be sure to place a test that is - dependent on another test later in the order. - -Exporting Tests ---------------- - -You can export tests so that they can run independently of the build -system. Exporting tests is required if you want to be able to hand the -test execution off to a scheduler. You can only export tests that are -defined in :term:`TEST_SUITES`. - -If your image is already built, make sure the following are set in your -``local.conf`` file:: - - INHERIT += "testexport" - TEST_TARGET_IP = "IP-address-for-the-test-target" - TEST_SERVER_IP = "IP-address-for-the-test-server" - -You can then export the tests with the -following BitBake command form:: - - $ bitbake image -c testexport - -Exporting the tests places them in the -:term:`Build Directory` in -``tmp/testexport/``\ image, which is controlled by the -:term:`TEST_EXPORT_DIR` variable. - -You can now run the tests outside of the build environment:: - - $ cd tmp/testexport/image - $ ./runexported.py testdata.json - -Here is a complete example that shows IP addresses and uses the -``core-image-sato`` image:: - - INHERIT += "testexport" - TEST_TARGET_IP = "192.168.7.2" - TEST_SERVER_IP = "192.168.7.1" - -Use BitBake to export the tests:: - - $ bitbake core-image-sato -c testexport - -Run the tests outside of -the build environment using the following:: - - $ cd tmp/testexport/core-image-sato - $ ./runexported.py testdata.json - -Writing New Tests ------------------ - -As mentioned previously, all new test files need to be in the proper -place for the build system to find them. New tests for additional -functionality outside of the core should be added to the layer that adds -the functionality, in ``layer/lib/oeqa/runtime/cases`` (as long as -:term:`BBPATH` is extended in the -layer's ``layer.conf`` file as normal). Just remember the following: - -- Filenames need to map directly to test (module) names. - -- Do not use module names that collide with existing core tests. - -- Minimally, an empty ``__init__.py`` file must be present in the runtime - directory. - -To create a new test, start by copying an existing module (e.g. -``syslog.py`` or ``gcc.py`` are good ones to use). Test modules can use -code from ``meta/lib/oeqa/utils``, which are helper classes. - -.. note:: - - Structure shell commands such that you rely on them and they return a - single code for success. Be aware that sometimes you will need to - parse the output. See the ``df.py`` and ``date.py`` modules for examples. - -You will notice that all test classes inherit ``oeRuntimeTest``, which -is found in ``meta/lib/oetest.py``. This base class offers some helper -attributes, which are described in the following sections: - -Class Methods -~~~~~~~~~~~~~ - -Class methods are as follows: - -- *hasPackage(pkg):* Returns "True" if ``pkg`` is in the installed - package list of the image, which is based on the manifest file that - is generated during the ``do_rootfs`` task. - -- *hasFeature(feature):* Returns "True" if the feature is in - :term:`IMAGE_FEATURES` or - :term:`DISTRO_FEATURES`. - -Class Attributes -~~~~~~~~~~~~~~~~ - -Class attributes are as follows: - -- *pscmd:* Equals "ps -ef" if ``procps`` is installed in the image. - Otherwise, ``pscmd`` equals "ps" (busybox). - -- *tc:* The called test context, which gives access to the - following attributes: - - - *d:* The BitBake datastore, which allows you to use stuff such - as ``oeRuntimeTest.tc.d.getVar("VIRTUAL-RUNTIME_init_manager")``. - - - *testslist and testsrequired:* Used internally. The tests - do not need these. - - - *filesdir:* The absolute path to - ``meta/lib/oeqa/runtime/files``, which contains helper files for - tests meant for copying on the target such as small files written - in C for compilation. - - - *target:* The target controller object used to deploy and - start an image on a particular target (e.g. Qemu, SimpleRemote, - and SystemdbootTarget). Tests usually use the following: - - - *ip:* The target's IP address. - - - *server_ip:* The host's IP address, which is usually used - by the DNF test suite. - - - *run(cmd, timeout=None):* The single, most used method. - This command is a wrapper for: ``ssh root@host "cmd"``. The - command returns a tuple: (status, output), which are what their - names imply - the return code of "cmd" and whatever output it - produces. The optional timeout argument represents the number - of seconds the test should wait for "cmd" to return. If the - argument is "None", the test uses the default instance's - timeout period, which is 300 seconds. If the argument is "0", - the test runs until the command returns. - - - *copy_to(localpath, remotepath):* - ``scp localpath root@ip:remotepath``. - - - *copy_from(remotepath, localpath):* - ``scp root@host:remotepath localpath``. - -Instance Attributes -~~~~~~~~~~~~~~~~~~~ - -There is a single instance attribute, which is ``target``. The ``target`` -instance attribute is identical to the class attribute of the same name, -which is described in the previous section. This attribute exists as -both an instance and class attribute so tests can use -``self.target.run(cmd)`` in instance methods instead of -``oeRuntimeTest.tc.target.run(cmd)``. - -Installing Packages in the DUT Without the Package Manager ----------------------------------------------------------- - -When a test requires a package built by BitBake, it is possible to -install that package. Installing the package does not require a package -manager be installed in the device under test (DUT). It does, however, -require an SSH connection and the target must be using the -``sshcontrol`` class. - -.. note:: - - This method uses ``scp`` to copy files from the host to the target, which - causes permissions and special attributes to be lost. - -A JSON file is used to define the packages needed by a test. This file -must be in the same path as the file used to define the tests. -Furthermore, the filename must map directly to the test module name with -a ``.json`` extension. - -The JSON file must include an object with the test name as keys of an -object or an array. This object (or array of objects) uses the following -data: - -- "pkg" - A mandatory string that is the name of the package to be - installed. - -- "rm" - An optional boolean, which defaults to "false", that specifies - to remove the package after the test. - -- "extract" - An optional boolean, which defaults to "false", that - specifies if the package must be extracted from the package format. - When set to "true", the package is not automatically installed into - the DUT. - -Following is an example JSON file that handles test "foo" installing -package "bar" and test "foobar" installing packages "foo" and "bar". -Once the test is complete, the packages are removed from the DUT. -:: - - { - "foo": { - "pkg": "bar" - }, - "foobar": [ - { - "pkg": "foo", - "rm": true - }, - { - "pkg": "bar", - "rm": true - } - ] - } - -Debugging Tools and Techniques -============================== - -The exact method for debugging build failures depends on the nature of -the problem and on the system's area from which the bug originates. -Standard debugging practices such as comparison against the last known -working version with examination of the changes and the re-application -of steps to identify the one causing the problem are valid for the Yocto -Project just as they are for any other system. Even though it is -impossible to detail every possible potential failure, this section -provides some general tips to aid in debugging given a variety of -situations. - -.. note:: - - A useful feature for debugging is the error reporting tool. - Configuring the Yocto Project to use this tool causes the - OpenEmbedded build system to produce error reporting commands as part - of the console output. You can enter the commands after the build - completes to log error information into a common database, that can - help you figure out what might be going wrong. For information on how - to enable and use this feature, see the - ":ref:`dev-manual/common-tasks:using the error reporting tool`" - section. - -The following list shows the debugging topics in the remainder of this -section: - -- ":ref:`dev-manual/common-tasks:viewing logs from failed tasks`" describes - how to find and view logs from tasks that failed during the build - process. - -- ":ref:`dev-manual/common-tasks:viewing variable values`" describes how to - use the BitBake ``-e`` option to examine variable values after a - recipe has been parsed. - -- ":ref:`dev-manual/common-tasks:viewing package information with \`\`oe-pkgdata-util\`\``" - describes how to use the ``oe-pkgdata-util`` utility to query - :term:`PKGDATA_DIR` and - display package-related information for built packages. - -- ":ref:`dev-manual/common-tasks:viewing dependencies between recipes and tasks`" - describes how to use the BitBake ``-g`` option to display recipe - dependency information used during the build. - -- ":ref:`dev-manual/common-tasks:viewing task variable dependencies`" describes - how to use the ``bitbake-dumpsig`` command in conjunction with key - subdirectories in the - :term:`Build Directory` to determine - variable dependencies. - -- ":ref:`dev-manual/common-tasks:running specific tasks`" describes - how to use several BitBake options (e.g. ``-c``, ``-C``, and ``-f``) - to run specific tasks in the build chain. It can be useful to run - tasks "out-of-order" when trying isolate build issues. - -- ":ref:`dev-manual/common-tasks:general bitbake problems`" describes how - to use BitBake's ``-D`` debug output option to reveal more about what - BitBake is doing during the build. - -- ":ref:`dev-manual/common-tasks:building with no dependencies`" - describes how to use the BitBake ``-b`` option to build a recipe - while ignoring dependencies. - -- ":ref:`dev-manual/common-tasks:recipe logging mechanisms`" - describes how to use the many recipe logging functions to produce - debugging output and report errors and warnings. - -- ":ref:`dev-manual/common-tasks:debugging parallel make races`" - describes how to debug situations where the build consists of several - parts that are run simultaneously and when the output or result of - one part is not ready for use with a different part of the build that - depends on that output. - -- ":ref:`dev-manual/common-tasks:debugging with the gnu project debugger (gdb) remotely`" - describes how to use GDB to allow you to examine running programs, which can - help you fix problems. - -- ":ref:`dev-manual/common-tasks:debugging with the gnu project debugger (gdb) on the target`" - describes how to use GDB directly on target hardware for debugging. - -- ":ref:`dev-manual/common-tasks:other debugging tips`" describes - miscellaneous debugging tips that can be useful. - -Viewing Logs from Failed Tasks ------------------------------- - -You can find the log for a task in the file -``${``\ :term:`WORKDIR`\ ``}/temp/log.do_``\ `taskname`. -For example, the log for the -:ref:`ref-tasks-compile` task of the -QEMU minimal image for the x86 machine (``qemux86``) might be in -``tmp/work/qemux86-poky-linux/core-image-minimal/1.0-r0/temp/log.do_compile``. -To see the commands :term:`BitBake` ran -to generate a log, look at the corresponding ``run.do_``\ `taskname` file -in the same directory. - -``log.do_``\ `taskname` and ``run.do_``\ `taskname` are actually symbolic -links to ``log.do_``\ `taskname`\ ``.``\ `pid` and -``log.run_``\ `taskname`\ ``.``\ `pid`, where `pid` is the PID the task had -when it ran. The symlinks always point to the files corresponding to the -most recent run. - -Viewing Variable Values ------------------------ - -Sometimes you need to know the value of a variable as a result of -BitBake's parsing step. This could be because some unexpected behavior -occurred in your project. Perhaps an attempt to :ref:`modify a variable -` did not work out as expected. - -BitBake's ``-e`` option is used to display variable values after -parsing. The following command displays the variable values after the -configuration files (i.e. ``local.conf``, ``bblayers.conf``, -``bitbake.conf`` and so forth) have been parsed:: - - $ bitbake -e - -The following command displays variable values after a specific recipe has -been parsed. The variables include those from the configuration as well:: - - $ bitbake -e recipename - -.. note:: - - Each recipe has its own private set of variables (datastore). - Internally, after parsing the configuration, a copy of the resulting - datastore is made prior to parsing each recipe. This copying implies - that variables set in one recipe will not be visible to other - recipes. - - Likewise, each task within a recipe gets a private datastore based on - the recipe datastore, which means that variables set within one task - will not be visible to other tasks. - -In the output of ``bitbake -e``, each variable is preceded by a -description of how the variable got its value, including temporary -values that were later overridden. This description also includes -variable flags (varflags) set on the variable. The output can be very -helpful during debugging. - -Variables that are exported to the environment are preceded by -``export`` in the output of ``bitbake -e``. See the following example:: - - export CC="i586-poky-linux-gcc -m32 -march=i586 --sysroot=/home/ulf/poky/build/tmp/sysroots/qemux86" - -In addition to variable values, the output of the ``bitbake -e`` and -``bitbake -e`` recipe commands includes the following information: - -- The output starts with a tree listing all configuration files and - classes included globally, recursively listing the files they include - or inherit in turn. Much of the behavior of the OpenEmbedded build - system (including the behavior of the :ref:`ref-manual/tasks:normal recipe build tasks`) is - implemented in the - :ref:`base ` class and the - classes it inherits, rather than being built into BitBake itself. - -- After the variable values, all functions appear in the output. For - shell functions, variables referenced within the function body are - expanded. If a function has been modified using overrides or using - override-style operators like ``:append`` and ``:prepend``, then the - final assembled function body appears in the output. - -Viewing Package Information with ``oe-pkgdata-util`` ----------------------------------------------------- - -You can use the ``oe-pkgdata-util`` command-line utility to query -:term:`PKGDATA_DIR` and display -various package-related information. When you use the utility, you must -use it to view information on packages that have already been built. - -Following are a few of the available ``oe-pkgdata-util`` subcommands. - -.. note:: - - You can use the standard \* and ? globbing wildcards as part of - package names and paths. - -- ``oe-pkgdata-util list-pkgs [pattern]``: Lists all packages - that have been built, optionally limiting the match to packages that - match pattern. - -- ``oe-pkgdata-util list-pkg-files package ...``: Lists the - files and directories contained in the given packages. - - .. note:: - - A different way to view the contents of a package is to look at - the - ``${``\ :term:`WORKDIR`\ ``}/packages-split`` - directory of the recipe that generates the package. This directory - is created by the - :ref:`ref-tasks-package` task - and has one subdirectory for each package the recipe generates, - which contains the files stored in that package. - - If you want to inspect the ``${WORKDIR}/packages-split`` - directory, make sure that - :ref:`rm_work ` is not - enabled when you build the recipe. - -- ``oe-pkgdata-util find-path path ...``: Lists the names of - the packages that contain the given paths. For example, the following - tells us that ``/usr/share/man/man1/make.1`` is contained in the - ``make-doc`` package:: - - $ oe-pkgdata-util find-path /usr/share/man/man1/make.1 - make-doc: /usr/share/man/man1/make.1 - -- ``oe-pkgdata-util lookup-recipe package ...``: Lists the name - of the recipes that produce the given packages. - -For more information on the ``oe-pkgdata-util`` command, use the help -facility:: - - $ oe-pkgdata-util --help - $ oe-pkgdata-util subcommand --help - -Viewing Dependencies Between Recipes and Tasks ----------------------------------------------- - -Sometimes it can be hard to see why BitBake wants to build other recipes -before the one you have specified. Dependency information can help you -understand why a recipe is built. - -To generate dependency information for a recipe, run the following -command:: - - $ bitbake -g recipename - -This command writes the following files in the current directory: - -- ``pn-buildlist``: A list of recipes/targets involved in building - `recipename`. "Involved" here means that at least one task from the - recipe needs to run when building `recipename` from scratch. Targets - that are in - :term:`ASSUME_PROVIDED` - are not listed. - -- ``task-depends.dot``: A graph showing dependencies between tasks. - -The graphs are in -`DOT `__ -format and can be converted to images (e.g. using the ``dot`` tool from -`Graphviz `__). - -.. note:: - - - DOT files use a plain text format. The graphs generated using the - ``bitbake -g`` command are often so large as to be difficult to - read without special pruning (e.g. with Bitbake's ``-I`` option) - and processing. Despite the form and size of the graphs, the - corresponding ``.dot`` files can still be possible to read and - provide useful information. - - As an example, the ``task-depends.dot`` file contains lines such - as the following:: - - "libxslt.do_configure" -> "libxml2.do_populate_sysroot" - - The above example line reveals that the - :ref:`ref-tasks-configure` - task in ``libxslt`` depends on the - :ref:`ref-tasks-populate_sysroot` - task in ``libxml2``, which is a normal - :term:`DEPENDS` dependency - between the two recipes. - - - For an example of how ``.dot`` files can be processed, see the - ``scripts/contrib/graph-tool`` Python script, which finds and - displays paths between graph nodes. - -You can use a different method to view dependency information by using -the following command:: - - $ bitbake -g -u taskexp recipename - -This command -displays a GUI window from which you can view build-time and runtime -dependencies for the recipes involved in building recipename. - -Viewing Task Variable Dependencies ----------------------------------- - -As mentioned in the -":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-execution:checksums (signatures)`" section of the BitBake -User Manual, BitBake tries to automatically determine what variables a -task depends on so that it can rerun the task if any values of the -variables change. This determination is usually reliable. However, if -you do things like construct variable names at runtime, then you might -have to manually declare dependencies on those variables using -``vardeps`` as described in the -":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata:variable flags`" section of the BitBake -User Manual. - -If you are unsure whether a variable dependency is being picked up -automatically for a given task, you can list the variable dependencies -BitBake has determined by doing the following: - -1. Build the recipe containing the task:: - - $ bitbake recipename - -2. Inside the :term:`STAMPS_DIR` - directory, find the signature data (``sigdata``) file that - corresponds to the task. The ``sigdata`` files contain a pickled - Python database of all the metadata that went into creating the input - checksum for the task. As an example, for the - :ref:`ref-tasks-fetch` task of the - ``db`` recipe, the ``sigdata`` file might be found in the following - location:: - - ${BUILDDIR}/tmp/stamps/i586-poky-linux/db/6.0.30-r1.do_fetch.sigdata.7c048c18222b16ff0bcee2000ef648b1 - - For tasks that are accelerated through the shared state - (:ref:`sstate `) cache, an - additional ``siginfo`` file is written into - :term:`SSTATE_DIR` along with - the cached task output. The ``siginfo`` files contain exactly the - same information as ``sigdata`` files. - -3. Run ``bitbake-dumpsig`` on the ``sigdata`` or ``siginfo`` file. Here - is an example:: - - $ bitbake-dumpsig ${BUILDDIR}/tmp/stamps/i586-poky-linux/db/6.0.30-r1.do_fetch.sigdata.7c048c18222b16ff0bcee2000ef648b1 - - In the output of the above command, you will find a line like the - following, which lists all the (inferred) variable dependencies for - the task. This list also includes indirect dependencies from - variables depending on other variables, recursively. - :: - - Task dependencies: ['PV', 'SRCREV', 'SRC_URI', 'SRC_URI[md5sum]', 'SRC_URI[sha256sum]', 'base_do_fetch'] - - .. note:: - - Functions (e.g. ``base_do_fetch``) also count as variable dependencies. - These functions in turn depend on the variables they reference. - - The output of ``bitbake-dumpsig`` also includes the value each - variable had, a list of dependencies for each variable, and - :term:`BB_BASEHASH_IGNORE_VARS` - information. - -There is also a ``bitbake-diffsigs`` command for comparing two -``siginfo`` or ``sigdata`` files. This command can be helpful when -trying to figure out what changed between two versions of a task. If you -call ``bitbake-diffsigs`` with just one file, the command behaves like -``bitbake-dumpsig``. - -You can also use BitBake to dump out the signature construction -information without executing tasks by using either of the following -BitBake command-line options:: - - ‐‐dump-signatures=SIGNATURE_HANDLER - -S SIGNATURE_HANDLER - - -.. note:: - - Two common values for `SIGNATURE_HANDLER` are "none" and "printdiff", which - dump only the signature or compare the dumped signature with the cached one, - respectively. - -Using BitBake with either of these options causes BitBake to dump out -``sigdata`` files in the ``stamps`` directory for every task it would -have executed instead of building the specified target package. - -Viewing Metadata Used to Create the Input Signature of a Shared State Task --------------------------------------------------------------------------- - -Seeing what metadata went into creating the input signature of a shared -state (sstate) task can be a useful debugging aid. This information is -available in signature information (``siginfo``) files in -:term:`SSTATE_DIR`. For -information on how to view and interpret information in ``siginfo`` -files, see the -":ref:`dev-manual/common-tasks:viewing task variable dependencies`" section. - -For conceptual information on shared state, see the -":ref:`overview-manual/concepts:shared state`" -section in the Yocto Project Overview and Concepts Manual. - -Invalidating Shared State to Force a Task to Run ------------------------------------------------- - -The OpenEmbedded build system uses -:ref:`checksums ` and -:ref:`overview-manual/concepts:shared state` cache to avoid unnecessarily -rebuilding tasks. Collectively, this scheme is known as "shared state -code". - -As with all schemes, this one has some drawbacks. It is possible that -you could make implicit changes to your code that the checksum -calculations do not take into account. These implicit changes affect a -task's output but do not trigger the shared state code into rebuilding a -recipe. Consider an example during which a tool changes its output. -Assume that the output of ``rpmdeps`` changes. The result of the change -should be that all the ``package`` and ``package_write_rpm`` shared -state cache items become invalid. However, because the change to the -output is external to the code and therefore implicit, the associated -shared state cache items do not become invalidated. In this case, the -build process uses the cached items rather than running the task again. -Obviously, these types of implicit changes can cause problems. - -To avoid these problems during the build, you need to understand the -effects of any changes you make. Realize that changes you make directly -to a function are automatically factored into the checksum calculation. -Thus, these explicit changes invalidate the associated area of shared -state cache. However, you need to be aware of any implicit changes that -are not obvious changes to the code and could affect the output of a -given task. - -When you identify an implicit change, you can easily take steps to -invalidate the cache and force the tasks to run. The steps you can take -are as simple as changing a function's comments in the source code. For -example, to invalidate package shared state files, change the comment -statements of -:ref:`ref-tasks-package` or the -comments of one of the functions it calls. Even though the change is -purely cosmetic, it causes the checksum to be recalculated and forces -the build system to run the task again. - -.. note:: - - For an example of a commit that makes a cosmetic change to invalidate - shared state, see this - :yocto_git:`commit `. - -Running Specific Tasks ----------------------- - -Any given recipe consists of a set of tasks. The standard BitBake -behavior in most cases is: ``do_fetch``, ``do_unpack``, ``do_patch``, -``do_configure``, ``do_compile``, ``do_install``, ``do_package``, -``do_package_write_*``, and ``do_build``. The default task is -``do_build`` and any tasks on which it depends build first. Some tasks, -such as ``do_devshell``, are not part of the default build chain. If you -wish to run a task that is not part of the default build chain, you can -use the ``-c`` option in BitBake. Here is an example:: - - $ bitbake matchbox-desktop -c devshell - -The ``-c`` option respects task dependencies, which means that all other -tasks (including tasks from other recipes) that the specified task -depends on will be run before the task. Even when you manually specify a -task to run with ``-c``, BitBake will only run the task if it considers -it "out of date". See the -":ref:`overview-manual/concepts:stamp files and the rerunning of tasks`" -section in the Yocto Project Overview and Concepts Manual for how -BitBake determines whether a task is "out of date". - -If you want to force an up-to-date task to be rerun (e.g. because you -made manual modifications to the recipe's -:term:`WORKDIR` that you want to try -out), then you can use the ``-f`` option. - -.. note:: - - The reason ``-f`` is never required when running the - :ref:`ref-tasks-devshell` task is because the - [\ :ref:`nostamp `\ ] - variable flag is already set for the task. - -The following example shows one way you can use the ``-f`` option:: - - $ bitbake matchbox-desktop - . - . - make some changes to the source code in the work directory - . - . - $ bitbake matchbox-desktop -c compile -f - $ bitbake matchbox-desktop - -This sequence first builds and then recompiles ``matchbox-desktop``. The -last command reruns all tasks (basically the packaging tasks) after the -compile. BitBake recognizes that the ``do_compile`` task was rerun and -therefore understands that the other tasks also need to be run again. - -Another, shorter way to rerun a task and all -:ref:`ref-manual/tasks:normal recipe build tasks` -that depend on it is to use the ``-C`` option. - -.. note:: - - This option is upper-cased and is separate from the ``-c`` - option, which is lower-cased. - -Using this option invalidates the given task and then runs the -:ref:`ref-tasks-build` task, which is -the default task if no task is given, and the tasks on which it depends. -You could replace the final two commands in the previous example with -the following single command:: - - $ bitbake matchbox-desktop -C compile - -Internally, the ``-f`` and ``-C`` options work by tainting (modifying) -the input checksum of the specified task. This tainting indirectly -causes the task and its dependent tasks to be rerun through the normal -task dependency mechanisms. - -.. note:: - - BitBake explicitly keeps track of which tasks have been tainted in - this fashion, and will print warnings such as the following for - builds involving such tasks: - - .. code-block:: none - - WARNING: /home/ulf/poky/meta/recipes-sato/matchbox-desktop/matchbox-desktop_2.1.bb.do_compile is tainted from a forced run - - - The purpose of the warning is to let you know that the work directory - and build output might not be in the clean state they would be in for - a "normal" build, depending on what actions you took. To get rid of - such warnings, you can remove the work directory and rebuild the - recipe, as follows:: - - $ bitbake matchbox-desktop -c clean - $ bitbake matchbox-desktop - - -You can view a list of tasks in a given package by running the -``do_listtasks`` task as follows:: - - $ bitbake matchbox-desktop -c listtasks - -The results appear as output to the console and are also in -the file ``${WORKDIR}/temp/log.do_listtasks``. - -General BitBake Problems ------------------------- - -You can see debug output from BitBake by using the ``-D`` option. The -debug output gives more information about what BitBake is doing and the -reason behind it. Each ``-D`` option you use increases the logging -level. The most common usage is ``-DDD``. - -The output from ``bitbake -DDD -v targetname`` can reveal why BitBake -chose a certain version of a package or why BitBake picked a certain -provider. This command could also help you in a situation where you -think BitBake did something unexpected. - -Building with No Dependencies ------------------------------ - -To build a specific recipe (``.bb`` file), you can use the following -command form:: - - $ bitbake -b somepath/somerecipe.bb - -This command form does -not check for dependencies. Consequently, you should use it only when -you know existing dependencies have been met. - -.. note:: - - You can also specify fragments of the filename. In this case, BitBake - checks for a unique match. - -Recipe Logging Mechanisms -------------------------- - -The Yocto Project provides several logging functions for producing -debugging output and reporting errors and warnings. For Python -functions, the following logging functions are available. All of these functions -log to ``${T}/log.do_``\ `task`, and can also log to standard output -(stdout) with the right settings: - -- ``bb.plain(msg)``: Writes msg as is to the log while also - logging to stdout. - -- ``bb.note(msg)``: Writes "NOTE: msg" to the log. Also logs to - stdout if BitBake is called with "-v". - -- ``bb.debug(level, msg)``: Writes "DEBUG: msg" to the - log. Also logs to stdout if the log level is greater than or equal to - level. See the ":ref:`bitbake:bitbake-user-manual/bitbake-user-manual-intro:usage and syntax`" option - in the BitBake User Manual for more information. - -- ``bb.warn(msg)``: Writes "WARNING: msg" to the log while also - logging to stdout. - -- ``bb.error(msg)``: Writes "ERROR: msg" to the log while also - logging to standard out (stdout). - - .. note:: - - Calling this function does not cause the task to fail. - -- ``bb.fatal(msg)``: This logging function is similar to - ``bb.error(msg)`` but also causes the calling task to fail. - - .. note:: - - ``bb.fatal()`` raises an exception, which means you do not need to put a - "return" statement after the function. - -The same logging functions are also available in shell functions, under -the names ``bbplain``, ``bbnote``, ``bbdebug``, ``bbwarn``, ``bberror``, -and ``bbfatal``. The -:ref:`logging ` class -implements these functions. See that class in the ``meta/classes`` -folder of the :term:`Source Directory` for information. - -Logging With Python -~~~~~~~~~~~~~~~~~~~ - -When creating recipes using Python and inserting code that handles build -logs, keep in mind the goal is to have informative logs while keeping -the console as "silent" as possible. Also, if you want status messages -in the log, use the "debug" loglevel. - -Following is an example written in Python. The code handles logging for -a function that determines the number of tasks needed to be run. See the -":ref:`ref-tasks-listtasks`" -section for additional information:: - - python do_listtasks() { - bb.debug(2, "Starting to figure out the task list") - if noteworthy_condition: - bb.note("There are 47 tasks to run") - bb.debug(2, "Got to point xyz") - if warning_trigger: - bb.warn("Detected warning_trigger, this might be a problem later.") - if recoverable_error: - bb.error("Hit recoverable_error, you really need to fix this!") - if fatal_error: - bb.fatal("fatal_error detected, unable to print the task list") - bb.plain("The tasks present are abc") - bb.debug(2, "Finished figuring out the tasklist") - } - -Logging With Bash -~~~~~~~~~~~~~~~~~ - -When creating recipes using Bash and inserting code that handles build -logs, you have the same goals - informative with minimal console output. -The syntax you use for recipes written in Bash is similar to that of -recipes written in Python described in the previous section. - -Following is an example written in Bash. The code logs the progress of -the ``do_my_function`` function. -:: - - do_my_function() { - bbdebug 2 "Running do_my_function" - if [ exceptional_condition ]; then - bbnote "Hit exceptional_condition" - fi - bbdebug 2 "Got to point xyz" - if [ warning_trigger ]; then - bbwarn "Detected warning_trigger, this might cause a problem later." - fi - if [ recoverable_error ]; then - bberror "Hit recoverable_error, correcting" - fi - if [ fatal_error ]; then - bbfatal "fatal_error detected" - fi - bbdebug 2 "Completed do_my_function" - } - - -Debugging Parallel Make Races ------------------------------ - -A parallel ``make`` race occurs when the build consists of several parts -that are run simultaneously and a situation occurs when the output or -result of one part is not ready for use with a different part of the -build that depends on that output. Parallel make races are annoying and -can sometimes be difficult to reproduce and fix. However, there are some simple -tips and tricks that can help you debug and fix them. This section -presents a real-world example of an error encountered on the Yocto -Project autobuilder and the process used to fix it. - -.. note:: - - If you cannot properly fix a ``make`` race condition, you can work around it - by clearing either the :term:`PARALLEL_MAKE` or :term:`PARALLEL_MAKEINST` - variables. - -The Failure -~~~~~~~~~~~ - -For this example, assume that you are building an image that depends on -the "neard" package. And, during the build, BitBake runs into problems -and creates the following output. - -.. note:: - - This example log file has longer lines artificially broken to make - the listing easier to read. - -If you examine the output or the log file, you see the failure during -``make``: - -.. code-block:: none - - | DEBUG: SITE files ['endian-little', 'bit-32', 'ix86-common', 'common-linux', 'common-glibc', 'i586-linux', 'common'] - | DEBUG: Executing shell function do_compile - | NOTE: make -j 16 - | make --no-print-directory all-am - | /bin/mkdir -p include/near - | /bin/mkdir -p include/near - | /bin/mkdir -p include/near - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/types.h include/near/types.h - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/log.h include/near/log.h - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/plugin.h include/near/plugin.h - | /bin/mkdir -p include/near - | /bin/mkdir -p include/near - | /bin/mkdir -p include/near - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/tag.h include/near/tag.h - | /bin/mkdir -p include/near - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/adapter.h include/near/adapter.h - | /bin/mkdir -p include/near - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/ndef.h include/near/ndef.h - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/tlv.h include/near/tlv.h - | /bin/mkdir -p include/near - | /bin/mkdir -p include/near - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/setting.h include/near/setting.h - | /bin/mkdir -p include/near - | /bin/mkdir -p include/near - | /bin/mkdir -p include/near - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/device.h include/near/device.h - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/nfc_copy.h include/near/nfc_copy.h - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/snep.h include/near/snep.h - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/version.h include/near/version.h - | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ - 0.14-r0/neard-0.14/include/dbus.h include/near/dbus.h - | ./src/genbuiltin nfctype1 nfctype2 nfctype3 nfctype4 p2p > src/builtin.h - | i586-poky-linux-gcc -m32 -march=i586 --sysroot=/home/pokybuild/yocto-autobuilder/nightly-x86/ - build/build/tmp/sysroots/qemux86 -DHAVE_CONFIG_H -I. -I./include -I./src -I./gdbus -I/home/pokybuild/ - yocto-autobuilder/nightly-x86/build/build/tmp/sysroots/qemux86/usr/include/glib-2.0 - -I/home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/sysroots/qemux86/usr/ - lib/glib-2.0/include -I/home/pokybuild/yocto-autobuilder/nightly-x86/build/build/ - tmp/sysroots/qemux86/usr/include/dbus-1.0 -I/home/pokybuild/yocto-autobuilder/ - nightly-x86/build/build/tmp/sysroots/qemux86/usr/lib/dbus-1.0/include -I/home/pokybuild/yocto-autobuilder/ - nightly-x86/build/build/tmp/sysroots/qemux86/usr/include/libnl3 - -DNEAR_PLUGIN_BUILTIN -DPLUGINDIR=\""/usr/lib/near/plugins"\" - -DCONFIGDIR=\""/etc/neard\"" -O2 -pipe -g -feliminate-unused-debug-types -c - -o tools/snep-send.o tools/snep-send.c - | In file included from tools/snep-send.c:16:0: - | tools/../src/near.h:41:23: fatal error: near/dbus.h: No such file or directory - | #include - | ^ - | compilation terminated. - | make[1]: *** [tools/snep-send.o] Error 1 - | make[1]: *** Waiting for unfinished jobs.... - | make: *** [all] Error 2 - | ERROR: oe_runmake failed - -Reproducing the Error -~~~~~~~~~~~~~~~~~~~~~ - -Because race conditions are intermittent, they do not manifest -themselves every time you do the build. In fact, most times the build -will complete without problems even though the potential race condition -exists. Thus, once the error surfaces, you need a way to reproduce it. - -In this example, compiling the "neard" package is causing the problem. -So the first thing to do is build "neard" locally. Before you start the -build, set the -:term:`PARALLEL_MAKE` variable -in your ``local.conf`` file to a high number (e.g. "-j 20"). Using a -high value for :term:`PARALLEL_MAKE` increases the chances of the race -condition showing up:: - - $ bitbake neard - -Once the local build for "neard" completes, start a ``devshell`` build:: - - $ bitbake neard -c devshell - -For information on how to use a ``devshell``, see the -":ref:`dev-manual/common-tasks:using a development shell`" section. - -In the ``devshell``, do the following:: - - $ make clean - $ make tools/snep-send.o - -The ``devshell`` commands cause the failure to clearly -be visible. In this case, there is a missing dependency for the ``neard`` -Makefile target. Here is some abbreviated, sample output with the -missing dependency clearly visible at the end:: - - i586-poky-linux-gcc -m32 -march=i586 --sysroot=/home/scott-lenovo/...... - . - . - . - tools/snep-send.c - In file included from tools/snep-send.c:16:0: - tools/../src/near.h:41:23: fatal error: near/dbus.h: No such file or directory - #include - ^ - compilation terminated. - make: *** [tools/snep-send.o] Error 1 - $ - - -Creating a Patch for the Fix -~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Because there is a missing dependency for the Makefile target, you need -to patch the ``Makefile.am`` file, which is generated from -``Makefile.in``. You can use Quilt to create the patch:: - - $ quilt new parallelmake.patch - Patch patches/parallelmake.patch is now on top - $ quilt add Makefile.am - File Makefile.am added to patch patches/parallelmake.patch - -For more information on using Quilt, see the -":ref:`dev-manual/common-tasks:using quilt in your workflow`" section. - -At this point you need to make the edits to ``Makefile.am`` to add the -missing dependency. For our example, you have to add the following line -to the file:: - - tools/snep-send.$(OBJEXT): include/near/dbus.h - -Once you have edited the file, use the ``refresh`` command to create the -patch:: - - $ quilt refresh - Refreshed patch patches/parallelmake.patch - -Once the patch file is created, you need to add it back to the originating -recipe folder. Here is an example assuming a top-level -:term:`Source Directory` named ``poky``:: - - $ cp patches/parallelmake.patch poky/meta/recipes-connectivity/neard/neard - -The final thing you need to do to implement the fix in the build is to -update the "neard" recipe (i.e. ``neard-0.14.bb``) so that the -:term:`SRC_URI` statement includes -the patch file. The recipe file is in the folder above the patch. Here -is what the edited :term:`SRC_URI` statement would look like:: - - SRC_URI = "${KERNELORG_MIRROR}/linux/network/nfc/${BPN}-${PV}.tar.xz \ - file://neard.in \ - file://neard.service.in \ - file://parallelmake.patch \ - " - -With the patch complete and moved to the correct folder and the -:term:`SRC_URI` statement updated, you can exit the ``devshell``:: - - $ exit - -Testing the Build -~~~~~~~~~~~~~~~~~ - -With everything in place, you can get back to trying the build again -locally:: - - $ bitbake neard - -This build should succeed. - -Now you can open up a ``devshell`` again and repeat the clean and make -operations as follows:: - - $ bitbake neard -c devshell - $ make clean - $ make tools/snep-send.o - -The build should work without issue. - -As with all solved problems, if they originated upstream, you need to -submit the fix for the recipe in OE-Core and upstream so that the -problem is taken care of at its source. See the -:doc:`../contributor-guide/submit-changes` section for more information. - -Debugging With the GNU Project Debugger (GDB) Remotely ------------------------------------------------------- - -GDB allows you to examine running programs, which in turn helps you to -understand and fix problems. It also allows you to perform post-mortem -style analysis of program crashes. GDB is available as a package within -the Yocto Project and is installed in SDK images by default. See the -":ref:`ref-manual/images:Images`" chapter in the Yocto -Project Reference Manual for a description of these images. You can find -information on GDB at https://sourceware.org/gdb/. - -.. note:: - - For best results, install debug (``-dbg``) packages for the applications you - are going to debug. Doing so makes extra debug symbols available that give - you more meaningful output. - -Sometimes, due to memory or disk space constraints, it is not possible -to use GDB directly on the remote target to debug applications. These -constraints arise because GDB needs to load the debugging information -and the binaries of the process being debugged. Additionally, GDB needs -to perform many computations to locate information such as function -names, variable names and values, stack traces and so forth - even -before starting the debugging process. These extra computations place -more load on the target system and can alter the characteristics of the -program being debugged. - -To help get past the previously mentioned constraints, there are two -methods you can use: running a debuginfod server and using gdbserver. - -Using the debuginfod server method -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -``debuginfod`` from ``elfutils`` is a way to distribute ``debuginfo`` files. -Running a ``debuginfod`` server makes debug symbols readily available, -which means you don't need to download debugging information -and the binaries of the process being debugged. You can just fetch -debug symbols from the server. - -To run a ``debuginfod`` server, you need to do the following: - -- Ensure that ``debuginfod`` is present in :term:`DISTRO_FEATURES` - (it already is in ``OpenEmbedded-core`` defaults and ``poky`` reference distribution). - If not, set in your distro config file or in ``local.conf``:: - - DISTRO_FEATURES:append = " debuginfod" - - This distro feature enables the server and client library in ``elfutils``, - and enables ``debuginfod`` support in clients (at the moment, ``gdb`` and ``binutils``). - -- Run the following commands to launch the ``debuginfod`` server on the host:: - - $ oe-debuginfod - -- To use ``debuginfod`` on the target, you need to know the ip:port where - ``debuginfod`` is listening on the host (port defaults to 8002), and export - that into the shell environment, for example in ``qemu``:: - - root@qemux86-64:~# export DEBUGINFOD_URLS="http://192.168.7.1:8002/" - -- Then debug info fetching should simply work when running the target ``gdb``, - ``readelf`` or ``objdump``, for example:: - - root@qemux86-64:~# gdb /bin/cat - ... - Reading symbols from /bin/cat... - Downloading separate debug info for /bin/cat... - Reading symbols from /home/root/.cache/debuginfod_client/923dc4780cfbc545850c616bffa884b6b5eaf322/debuginfo... - -- It's also possible to use ``debuginfod-find`` to just query the server:: - - root@qemux86-64:~# debuginfod-find debuginfo /bin/ls - /home/root/.cache/debuginfod_client/356edc585f7f82d46f94fcb87a86a3fe2d2e60bd/debuginfo - - -Using the gdbserver method -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -gdbserver, which runs on the remote target and does not load any -debugging information from the debugged process. Instead, a GDB instance -processes the debugging information that is run on a remote computer - -the host GDB. The host GDB then sends control commands to gdbserver to -make it stop or start the debugged program, as well as read or write -memory regions of that debugged program. All the debugging information -loaded and processed as well as all the heavy debugging is done by the -host GDB. Offloading these processes gives the gdbserver running on the -target a chance to remain small and fast. - -Because the host GDB is responsible for loading the debugging -information and for doing the necessary processing to make actual -debugging happen, you have to make sure the host can access the -unstripped binaries complete with their debugging information and also -be sure the target is compiled with no optimizations. The host GDB must -also have local access to all the libraries used by the debugged -program. Because gdbserver does not need any local debugging -information, the binaries on the remote target can remain stripped. -However, the binaries must also be compiled without optimization so they -match the host's binaries. - -To remain consistent with GDB documentation and terminology, the binary -being debugged on the remote target machine is referred to as the -"inferior" binary. For documentation on GDB see the `GDB -site `__. - -The following steps show you how to debug using the GNU project -debugger. - -1. *Configure your build system to construct the companion debug - filesystem:* - - In your ``local.conf`` file, set the following:: - - IMAGE_GEN_DEBUGFS = "1" - IMAGE_FSTYPES_DEBUGFS = "tar.bz2" - - These options cause the - OpenEmbedded build system to generate a special companion filesystem - fragment, which contains the matching source and debug symbols to - your deployable filesystem. The build system does this by looking at - what is in the deployed filesystem, and pulling the corresponding - ``-dbg`` packages. - - The companion debug filesystem is not a complete filesystem, but only - contains the debug fragments. This filesystem must be combined with - the full filesystem for debugging. Subsequent steps in this procedure - show how to combine the partial filesystem with the full filesystem. - -2. *Configure the system to include gdbserver in the target filesystem:* - - Make the following addition in either your ``local.conf`` file or in - an image recipe:: - - IMAGE_INSTALL:append = " gdbserver" - - The change makes - sure the ``gdbserver`` package is included. - -3. *Build the environment:* - - Use the following command to construct the image and the companion - Debug Filesystem:: - - $ bitbake image - - Build the cross GDB component and - make it available for debugging. Build the SDK that matches the - image. Building the SDK is best for a production build that can be - used later for debugging, especially during long term maintenance:: - - $ bitbake -c populate_sdk image - - Alternatively, you can build the minimal toolchain components that - match the target. Doing so creates a smaller than typical SDK and - only contains a minimal set of components with which to build simple - test applications, as well as run the debugger:: - - $ bitbake meta-toolchain - - A final method is to build Gdb itself within the build system:: - - $ bitbake gdb-cross- - - Doing so produces a temporary copy of - ``cross-gdb`` you can use for debugging during development. While - this is the quickest approach, the two previous methods in this step - are better when considering long-term maintenance strategies. - - .. note:: - - If you run ``bitbake gdb-cross``, the OpenEmbedded build system suggests - the actual image (e.g. ``gdb-cross-i586``). The suggestion is usually the - actual name you want to use. - -4. *Set up the* ``debugfs``\ *:* - - Run the following commands to set up the ``debugfs``:: - - $ mkdir debugfs - $ cd debugfs - $ tar xvfj build-dir/tmp-glibc/deploy/images/machine/image.rootfs.tar.bz2 - $ tar xvfj build-dir/tmp-glibc/deploy/images/machine/image-dbg.rootfs.tar.bz2 - -5. *Set up GDB:* - - Install the SDK (if you built one) and then source the correct - environment file. Sourcing the environment file puts the SDK in your - ``PATH`` environment variable. - - If you are using the build system, Gdb is located in - `build-dir`\ ``/tmp/sysroots/``\ `host`\ ``/usr/bin/``\ `architecture`\ ``/``\ `architecture`\ ``-gdb`` - -6. *Boot the target:* - - For information on how to run QEMU, see the `QEMU - Documentation `__. - - .. note:: - - Be sure to verify that your host can access the target via TCP. - -7. *Debug a program:* - - Debugging a program involves running gdbserver on the target and then - running Gdb on the host. The example in this step debugs ``gzip``: - - .. code-block:: shell - - root@qemux86:~# gdbserver localhost:1234 /bin/gzip —help - - For - additional gdbserver options, see the `GDB Server - Documentation `__. - - After running gdbserver on the target, you need to run Gdb on the - host and configure it and connect to the target. Use these commands:: - - $ cd directory-holding-the-debugfs-directory - $ arch-gdb - (gdb) set sysroot debugfs - (gdb) set substitute-path /usr/src/debug debugfs/usr/src/debug - (gdb) target remote IP-of-target:1234 - - At this - point, everything should automatically load (i.e. matching binaries, - symbols and headers). - - .. note:: - - The Gdb ``set`` commands in the previous example can be placed into the - users ``~/.gdbinit`` file. Upon starting, Gdb automatically runs whatever - commands are in that file. - -8. *Deploying without a full image rebuild:* - - In many cases, during development you want a quick method to deploy a - new binary to the target and debug it, without waiting for a full - image build. - - One approach to solving this situation is to just build the component - you want to debug. Once you have built the component, copy the - executable directly to both the target and the host ``debugfs``. - - If the binary is processed through the debug splitting in - OpenEmbedded, you should also copy the debug items (i.e. ``.debug`` - contents and corresponding ``/usr/src/debug`` files) from the work - directory. Here is an example:: - - $ bitbake bash - $ bitbake -c devshell bash - $ cd .. - $ scp packages-split/bash/bin/bash target:/bin/bash - $ cp -a packages-split/bash-dbg/\* path/debugfs - -Debugging with the GNU Project Debugger (GDB) on the Target ------------------------------------------------------------ - -The previous section addressed using GDB remotely for debugging -purposes, which is the most usual case due to the inherent hardware -limitations on many embedded devices. However, debugging in the target -hardware itself is also possible with more powerful devices. This -section describes what you need to do in order to support using GDB to -debug on the target hardware. - -To support this kind of debugging, you need do the following: - -- Ensure that GDB is on the target. You can do this by adding "gdb" to - :term:`IMAGE_INSTALL`:: - - IMAGE_INSTALL:append = " gdb" - - Alternatively, you can add "tools-debug" to :term:`IMAGE_FEATURES`:: - - IMAGE_FEATURES:append = " tools-debug" - -- Ensure that debug symbols are present. You can make sure these - symbols are present by installing ``-dbg``:: - - IMAGE_INSTALL:append = "packagename-dbg" - - Alternatively, you can do the following to include - all the debug symbols:: - - IMAGE_FEATURES:append = " dbg-pkgs" - -.. note:: - - To improve the debug information accuracy, you can reduce the level - of optimization used by the compiler. For example, when adding the - following line to your ``local.conf`` file, you will reduce optimization - from :term:`FULL_OPTIMIZATION` of "-O2" to :term:`DEBUG_OPTIMIZATION` - of "-O -fno-omit-frame-pointer":: - - DEBUG_BUILD = "1" - - Consider that this will reduce the application's performance and is - recommended only for debugging purposes. - -Other Debugging Tips --------------------- - -Here are some other tips that you might find useful: - -- When adding new packages, it is worth watching for undesirable items - making their way into compiler command lines. For example, you do not - want references to local system files like ``/usr/lib/`` or - ``/usr/include/``. - -- If you want to remove the ``psplash`` boot splashscreen, add - ``psplash=false`` to the kernel command line. Doing so prevents - ``psplash`` from loading and thus allows you to see the console. It - is also possible to switch out of the splashscreen by switching the - virtual console (e.g. Fn+Left or Fn+Right on a Zaurus). - -- Removing :term:`TMPDIR` (usually - ``tmp/``, within the - :term:`Build Directory`) can often fix - temporary build issues. Removing :term:`TMPDIR` is usually a relatively - cheap operation, because task output will be cached in - :term:`SSTATE_DIR` (usually - ``sstate-cache/``, which is also in the Build Directory). - - .. note:: - - Removing :term:`TMPDIR` might be a workaround rather than a fix. - Consequently, trying to determine the underlying cause of an issue before - removing the directory is a good idea. - -- Understanding how a feature is used in practice within existing - recipes can be very helpful. It is recommended that you configure - some method that allows you to quickly search through files. - - Using GNU Grep, you can use the following shell function to - recursively search through common recipe-related files, skipping - binary files, ``.git`` directories, and the Build Directory (assuming - its name starts with "build"):: - - g() { - grep -Ir \ - --exclude-dir=.git \ - --exclude-dir='build*' \ - --include='*.bb*' \ - --include='*.inc*' \ - --include='*.conf*' \ - --include='*.py*' \ - "$@" - } - - Following are some usage examples:: - - $ g FOO # Search recursively for "FOO" - $ g -i foo # Search recursively for "foo", ignoring case - $ g -w FOO # Search recursively for "FOO" as a word, ignoring e.g. "FOOBAR" - - If figuring - out how some feature works requires a lot of searching, it might - indicate that the documentation should be extended or improved. In - such cases, consider filing a documentation bug using the Yocto - Project implementation of - :yocto_bugs:`Bugzilla <>`. For information on - how to submit a bug against the Yocto Project, see the Yocto Project - Bugzilla :yocto_wiki:`wiki page ` - and the ":doc:`../contributor-guide/report-defect`" section. - - .. note:: - - The manuals might not be the right place to document variables - that are purely internal and have a limited scope (e.g. internal - variables used to implement a single ``.bbclass`` file). - -Working With Licenses -===================== - -As mentioned in the ":ref:`overview-manual/development-environment:licensing`" -section in the Yocto Project Overview and Concepts Manual, open source -projects are open to the public and they consequently have different -licensing structures in place. This section describes the mechanism by -which the :term:`OpenEmbedded Build System` -tracks changes to -licensing text and covers how to maintain open source license compliance -during your project's lifecycle. The section also describes how to -enable commercially licensed recipes, which by default are disabled. - -Tracking License Changes ------------------------- - -The license of an upstream project might change in the future. In order -to prevent these changes going unnoticed, the -:term:`LIC_FILES_CHKSUM` -variable tracks changes to the license text. The checksums are validated -at the end of the configure step, and if the checksums do not match, the -build will fail. - -Specifying the ``LIC_FILES_CHKSUM`` Variable -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The :term:`LIC_FILES_CHKSUM` variable contains checksums of the license text -in the source code for the recipe. Following is an example of how to -specify :term:`LIC_FILES_CHKSUM`:: - - LIC_FILES_CHKSUM = "file://COPYING;md5=xxxx \ - file://licfile1.txt;beginline=5;endline=29;md5=yyyy \ - file://licfile2.txt;endline=50;md5=zzzz \ - ..." - -.. note:: - - - When using "beginline" and "endline", realize that line numbering - begins with one and not zero. Also, the included lines are - inclusive (i.e. lines five through and including 29 in the - previous example for ``licfile1.txt``). - - - When a license check fails, the selected license text is included - as part of the QA message. Using this output, you can determine - the exact start and finish for the needed license text. - -The build system uses the :term:`S` -variable as the default directory when searching files listed in -:term:`LIC_FILES_CHKSUM`. The previous example employs the default -directory. - -Consider this next example:: - - LIC_FILES_CHKSUM = "file://src/ls.c;beginline=5;endline=16;\ - md5=bb14ed3c4cda583abc85401304b5cd4e" - LIC_FILES_CHKSUM = "file://${WORKDIR}/license.html;md5=5c94767cedb5d6987c902ac850ded2c6" - -The first line locates a file in ``${S}/src/ls.c`` and isolates lines -five through 16 as license text. The second line refers to a file in -:term:`WORKDIR`. - -Note that :term:`LIC_FILES_CHKSUM` variable is mandatory for all recipes, -unless the :term:`LICENSE` variable is set to "CLOSED". - -Explanation of Syntax -~~~~~~~~~~~~~~~~~~~~~ - -As mentioned in the previous section, the :term:`LIC_FILES_CHKSUM` variable -lists all the important files that contain the license text for the -source code. It is possible to specify a checksum for an entire file, or -a specific section of a file (specified by beginning and ending line -numbers with the "beginline" and "endline" parameters, respectively). -The latter is useful for source files with a license notice header, -README documents, and so forth. If you do not use the "beginline" -parameter, then it is assumed that the text begins on the first line of -the file. Similarly, if you do not use the "endline" parameter, it is -assumed that the license text ends with the last line of the file. - -The "md5" parameter stores the md5 checksum of the license text. If the -license text changes in any way as compared to this parameter then a -mismatch occurs. This mismatch triggers a build failure and notifies the -developer. Notification allows the developer to review and address the -license text changes. Also note that if a mismatch occurs during the -build, the correct md5 checksum is placed in the build log and can be -easily copied to the recipe. - -There is no limit to how many files you can specify using the -:term:`LIC_FILES_CHKSUM` variable. Generally, however, every project -requires a few specifications for license tracking. Many projects have a -"COPYING" file that stores the license information for all the source -code files. This practice allows you to just track the "COPYING" file as -long as it is kept up to date. - -.. note:: - - - If you specify an empty or invalid "md5" parameter, - :term:`BitBake` returns an md5 - mis-match error and displays the correct "md5" parameter value - during the build. The correct parameter is also captured in the - build log. - - - If the whole file contains only license text, you do not need to - use the "beginline" and "endline" parameters. - -Enabling Commercially Licensed Recipes --------------------------------------- - -By default, the OpenEmbedded build system disables components that have -commercial or other special licensing requirements. Such requirements -are defined on a recipe-by-recipe basis through the -:term:`LICENSE_FLAGS` variable -definition in the affected recipe. For instance, the -``poky/meta/recipes-multimedia/gstreamer/gst-plugins-ugly`` recipe -contains the following statement:: - - LICENSE_FLAGS = "commercial" - -Here is a -slightly more complicated example that contains both an explicit recipe -name and version (after variable expansion):: - - LICENSE_FLAGS = "license_${PN}_${PV}" - -In order for a component restricted by a -:term:`LICENSE_FLAGS` definition to be enabled and included in an image, it -needs to have a matching entry in the global -:term:`LICENSE_FLAGS_ACCEPTED` -variable, which is a variable typically defined in your ``local.conf`` -file. For example, to enable the -``poky/meta/recipes-multimedia/gstreamer/gst-plugins-ugly`` package, you -could add either the string "commercial_gst-plugins-ugly" or the more -general string "commercial" to :term:`LICENSE_FLAGS_ACCEPTED`. See the -":ref:`dev-manual/common-tasks:license flag matching`" section for a full -explanation of how :term:`LICENSE_FLAGS` matching works. Here is the -example:: - - LICENSE_FLAGS_ACCEPTED = "commercial_gst-plugins-ugly" - -Likewise, to additionally enable the package built from the recipe -containing ``LICENSE_FLAGS = "license_${PN}_${PV}"``, and assuming that -the actual recipe name was ``emgd_1.10.bb``, the following string would -enable that package as well as the original ``gst-plugins-ugly`` -package:: - - LICENSE_FLAGS_ACCEPTED = "commercial_gst-plugins-ugly license_emgd_1.10" - -As a convenience, you do not need to specify the -complete license string for every package. You can use -an abbreviated form, which consists of just the first portion or -portions of the license string before the initial underscore character -or characters. A partial string will match any license that contains the -given string as the first portion of its license. For example, the -following value will also match both of the packages -previously mentioned as well as any other packages that have licenses -starting with "commercial" or "license". -:: - - LICENSE_FLAGS_ACCEPTED = "commercial license" - -License Flag Matching -~~~~~~~~~~~~~~~~~~~~~ - -License flag matching allows you to control what recipes the -OpenEmbedded build system includes in the build. Fundamentally, the -build system attempts to match :term:`LICENSE_FLAGS` strings found in -recipes against strings found in :term:`LICENSE_FLAGS_ACCEPTED`. -A match causes the build system to include a recipe in the -build, while failure to find a match causes the build system to exclude -a recipe. - -In general, license flag matching is simple. However, understanding some -concepts will help you correctly and effectively use matching. - -Before a flag defined by a particular recipe is tested against the -entries of :term:`LICENSE_FLAGS_ACCEPTED`, the expanded -string ``_${PN}`` is appended to the flag. This expansion makes each -:term:`LICENSE_FLAGS` value recipe-specific. After expansion, the -string is then matched against the entries. Thus, specifying -``LICENSE_FLAGS = "commercial"`` in recipe "foo", for example, results -in the string ``"commercial_foo"``. And, to create a match, that string -must appear among the entries of :term:`LICENSE_FLAGS_ACCEPTED`. - -Judicious use of the :term:`LICENSE_FLAGS` strings and the contents of the -:term:`LICENSE_FLAGS_ACCEPTED` variable allows you a lot of flexibility for -including or excluding recipes based on licensing. For example, you can -broaden the matching capabilities by using license flags string subsets -in :term:`LICENSE_FLAGS_ACCEPTED`. - -.. note:: - - When using a string subset, be sure to use the part of the expanded - string that precedes the appended underscore character (e.g. - ``usethispart_1.3``, ``usethispart_1.4``, and so forth). - -For example, simply specifying the string "commercial" in the -:term:`LICENSE_FLAGS_ACCEPTED` variable matches any expanded -:term:`LICENSE_FLAGS` definition that starts with the string -"commercial" such as "commercial_foo" and "commercial_bar", which -are the strings the build system automatically generates for -hypothetical recipes named "foo" and "bar" assuming those recipes simply -specify the following:: - - LICENSE_FLAGS = "commercial" - -Thus, you can choose to exhaustively enumerate each license flag in the -list and allow only specific recipes into the image, or you can use a -string subset that causes a broader range of matches to allow a range of -recipes into the image. - -This scheme works even if the :term:`LICENSE_FLAGS` string already has -``_${PN}`` appended. For example, the build system turns the license -flag "commercial_1.2_foo" into "commercial_1.2_foo_foo" and would match -both the general "commercial" and the specific "commercial_1.2_foo" -strings found in the :term:`LICENSE_FLAGS_ACCEPTED` variable, as expected. - -Here are some other scenarios: - -- You can specify a versioned string in the recipe such as - "commercial_foo_1.2" in a "foo" recipe. The build system expands this - string to "commercial_foo_1.2_foo". Combine this license flag with a - :term:`LICENSE_FLAGS_ACCEPTED` variable that has the string - "commercial" and you match the flag along with any other flag that - starts with the string "commercial". - -- Under the same circumstances, you can add "commercial_foo" in the - :term:`LICENSE_FLAGS_ACCEPTED` variable and the build system not only - matches "commercial_foo_1.2" but also matches any license flag with - the string "commercial_foo", regardless of the version. - -- You can be very specific and use both the package and version parts - in the :term:`LICENSE_FLAGS_ACCEPTED` list (e.g. - "commercial_foo_1.2") to specifically match a versioned recipe. - -Other Variables Related to Commercial Licenses -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -There are other helpful variables related to commercial license handling, -defined in the -``poky/meta/conf/distro/include/default-distrovars.inc`` file:: - - COMMERCIAL_AUDIO_PLUGINS ?= "" - COMMERCIAL_VIDEO_PLUGINS ?= "" - -If you -want to enable these components, you can do so by making sure you have -statements similar to the following in your ``local.conf`` configuration -file:: - - COMMERCIAL_AUDIO_PLUGINS = "gst-plugins-ugly-mad \ - gst-plugins-ugly-mpegaudioparse" - COMMERCIAL_VIDEO_PLUGINS = "gst-plugins-ugly-mpeg2dec \ - gst-plugins-ugly-mpegstream gst-plugins-bad-mpegvideoparse" - LICENSE_FLAGS_ACCEPTED = "commercial_gst-plugins-ugly commercial_gst-plugins-bad commercial_qmmp" - - -Of course, you could also create a matching list for those -components using the more general "commercial" in the -:term:`LICENSE_FLAGS_ACCEPTED` variable, but that would also enable all -the other packages with :term:`LICENSE_FLAGS` -containing "commercial", which you may or may not want:: - - LICENSE_FLAGS_ACCEPTED = "commercial" - -Specifying audio and video plugins as part of the -``COMMERCIAL_AUDIO_PLUGINS`` and ``COMMERCIAL_VIDEO_PLUGINS`` statements -(along with the enabling :term:`LICENSE_FLAGS_ACCEPTED`) includes the -plugins or components into built images, thus adding support for media -formats or components. - -Maintaining Open Source License Compliance During Your Product's Lifecycle --------------------------------------------------------------------------- - -One of the concerns for a development organization using open source -software is how to maintain compliance with various open source -licensing during the lifecycle of the product. While this section does -not provide legal advice or comprehensively cover all scenarios, it does -present methods that you can use to assist you in meeting the compliance -requirements during a software release. - -With hundreds of different open source licenses that the Yocto Project -tracks, it is difficult to know the requirements of each and every -license. However, the requirements of the major FLOSS licenses can begin -to be covered by assuming that there are three main areas of concern: - -- Source code must be provided. - -- License text for the software must be provided. - -- Compilation scripts and modifications to the source code must be - provided. - -- spdx files can be provided. - -There are other requirements beyond the scope of these three and the -methods described in this section (e.g. the mechanism through which -source code is distributed). - -As different organizations have different methods of complying with open -source licensing, this section is not meant to imply that there is only -one single way to meet your compliance obligations, but rather to -describe one method of achieving compliance. The remainder of this -section describes methods supported to meet the previously mentioned -three requirements. Once you take steps to meet these requirements, and -prior to releasing images, sources, and the build system, you should -audit all artifacts to ensure completeness. - -.. note:: - - The Yocto Project generates a license manifest during image creation - that is located in ``${DEPLOY_DIR}/licenses/``\ `image_name`\ ``-``\ `datestamp` - to assist with any audits. - -Providing the Source Code -~~~~~~~~~~~~~~~~~~~~~~~~~ - -Compliance activities should begin before you generate the final image. -The first thing you should look at is the requirement that tops the list -for most compliance groups - providing the source. The Yocto Project has -a few ways of meeting this requirement. - -One of the easiest ways to meet this requirement is to provide the -entire :term:`DL_DIR` used by the -build. This method, however, has a few issues. The most obvious is the -size of the directory since it includes all sources used in the build -and not just the source used in the released image. It will include -toolchain source, and other artifacts, which you would not generally -release. However, the more serious issue for most companies is -accidental release of proprietary software. The Yocto Project provides -an :ref:`archiver ` class to -help avoid some of these concerns. - -Before you employ :term:`DL_DIR` or the :ref:`archiver ` class, you need to -decide how you choose to provide source. The source ``archiver`` class -can generate tarballs and SRPMs and can create them with various levels -of compliance in mind. - -One way of doing this (but certainly not the only way) is to release -just the source as a tarball. You can do this by adding the following to -the ``local.conf`` file found in the -:term:`Build Directory`:: - - INHERIT += "archiver" - ARCHIVER_MODE[src] = "original" - -During the creation of your -image, the source from all recipes that deploy packages to the image is -placed within subdirectories of ``DEPLOY_DIR/sources`` based on the -:term:`LICENSE` for each recipe. -Releasing the entire directory enables you to comply with requirements -concerning providing the unmodified source. It is important to note that -the size of the directory can get large. - -A way to help mitigate the size issue is to only release tarballs for -licenses that require the release of source. Let us assume you are only -concerned with GPL code as identified by running the following script: - -.. code-block:: shell - - # Script to archive a subset of packages matching specific license(s) - # Source and license files are copied into sub folders of package folder - # Must be run from build folder - #!/bin/bash - src_release_dir="source-release" - mkdir -p $src_release_dir - for a in tmp/deploy/sources/*; do - for d in $a/*; do - # Get package name from path - p=`basename $d` - p=${p%-*} - p=${p%-*} - # Only archive GPL packages (update *GPL* regex for your license check) - numfiles=`ls tmp/deploy/licenses/$p/*GPL* 2> /dev/null | wc -l` - if [ $numfiles -ge 1 ]; then - echo Archiving $p - mkdir -p $src_release_dir/$p/source - cp $d/* $src_release_dir/$p/source 2> /dev/null - mkdir -p $src_release_dir/$p/license - cp tmp/deploy/licenses/$p/* $src_release_dir/$p/license 2> /dev/null - fi - done - done - -At this point, you -could create a tarball from the ``gpl_source_release`` directory and -provide that to the end user. This method would be a step toward -achieving compliance with section 3a of GPLv2 and with section 6 of -GPLv3. - -Providing License Text -~~~~~~~~~~~~~~~~~~~~~~ - -One requirement that is often overlooked is inclusion of license text. -This requirement also needs to be dealt with prior to generating the -final image. Some licenses require the license text to accompany the -binary. You can achieve this by adding the following to your -``local.conf`` file:: - - COPY_LIC_MANIFEST = "1" - COPY_LIC_DIRS = "1" - LICENSE_CREATE_PACKAGE = "1" - -Adding these statements to the -configuration file ensures that the licenses collected during package -generation are included on your image. - -.. note:: - - Setting all three variables to "1" results in the image having two - copies of the same license file. One copy resides in - ``/usr/share/common-licenses`` and the other resides in - ``/usr/share/license``. - - The reason for this behavior is because - :term:`COPY_LIC_DIRS` and - :term:`COPY_LIC_MANIFEST` - add a copy of the license when the image is built but do not offer a - path for adding licenses for newly installed packages to an image. - :term:`LICENSE_CREATE_PACKAGE` - adds a separate package and an upgrade path for adding licenses to an - image. - -As the source ``archiver`` class has already archived the original -unmodified source that contains the license files, you would have -already met the requirements for inclusion of the license information -with source as defined by the GPL and other open source licenses. - -Providing Compilation Scripts and Source Code Modifications -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -At this point, we have addressed all we need to prior to generating the -image. The next two requirements are addressed during the final -packaging of the release. - -By releasing the version of the OpenEmbedded build system and the layers -used during the build, you will be providing both compilation scripts -and the source code modifications in one step. - -If the deployment team has a :ref:`overview-manual/concepts:bsp layer` -and a distro layer, and those -those layers are used to patch, compile, package, or modify (in any way) -any open source software included in your released images, you might be -required to release those layers under section 3 of GPLv2 or section 1 -of GPLv3. One way of doing that is with a clean checkout of the version -of the Yocto Project and layers used during your build. Here is an -example: - -.. code-block:: shell - - # We built using the dunfell branch of the poky repo - $ git clone -b dunfell git://git.yoctoproject.org/poky - $ cd poky - # We built using the release_branch for our layers - $ git clone -b release_branch git://git.mycompany.com/meta-my-bsp-layer - $ git clone -b release_branch git://git.mycompany.com/meta-my-software-layer - # clean up the .git repos - $ find . -name ".git" -type d -exec rm -rf {} \; - -One -thing a development organization might want to consider for end-user -convenience is to modify ``meta-poky/conf/bblayers.conf.sample`` to -ensure that when the end user utilizes the released build system to -build an image, the development organization's layers are included in -the ``bblayers.conf`` file automatically:: - - # POKY_BBLAYERS_CONF_VERSION is increased each time build/conf/bblayers.conf - # changes incompatibly - POKY_BBLAYERS_CONF_VERSION = "2" - - BBPATH = "${TOPDIR}" - BBFILES ?= "" - - BBLAYERS ?= " \ - ##OEROOT##/meta \ - ##OEROOT##/meta-poky \ - ##OEROOT##/meta-yocto-bsp \ - ##OEROOT##/meta-mylayer \ - " - -Creating and -providing an archive of the :term:`Metadata` -layers (recipes, configuration files, and so forth) enables you to meet -your requirements to include the scripts to control compilation as well -as any modifications to the original source. - -Compliance Limitations with Executables Built from Static Libraries -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -When package A is added to an image via the :term:`RDEPENDS` or :term:`RRECOMMENDS` -mechanisms as well as explicitly included in the image recipe with -:term:`IMAGE_INSTALL`, and depends on a static linked library recipe B -(``DEPENDS += "B"``), package B will neither appear in the generated license -manifest nor in the generated source tarballs. This occurs as the -:ref:`license ` and :ref:`archiver ` -classes assume that only packages included via :term:`RDEPENDS` or :term:`RRECOMMENDS` -end up in the image. - -As a result, potential obligations regarding license compliance for package B -may not be met. - -The Yocto Project doesn't enable static libraries by default, in part because -of this issue. Before a solution to this limitation is found, you need to -keep in mind that if your root filesystem is built from static libraries, -you will need to manually ensure that your deliveries are compliant -with the licenses of these libraries. - -Copying Non Standard Licenses ------------------------------ - -Some packages, such as the linux-firmware package, have many licenses -that are not in any way common. You can avoid adding a lot of these -types of common license files, which are only applicable to a specific -package, by using the -:term:`NO_GENERIC_LICENSE` -variable. Using this variable also avoids QA errors when you use a -non-common, non-CLOSED license in a recipe. - -Here is an example that uses the ``LICENSE.Abilis.txt`` file as -the license from the fetched source:: - - NO_GENERIC_LICENSE[Firmware-Abilis] = "LICENSE.Abilis.txt" - -Checking for Vulnerabilities -============================ - -Vulnerabilities in Poky and OE-Core ------------------------------------ - -The Yocto Project has an infrastructure to track and address unfixed -known security vulnerabilities, as tracked by the public -:wikipedia:`Common Vulnerabilities and Exposures (CVE) ` -database. - -The Yocto Project maintains a `list of known vulnerabilities -`__ -for packages in Poky and OE-Core, tracking the evolution of the number of -unpatched CVEs and the status of patches. Such information is available for -the current development version and for each supported release. - -Security is a process, not a product, and thus at any time, a number of security -issues may be impacting Poky and OE-Core. It is up to the maintainers, users, -contributors and anyone interested in the issues to investigate and possibly fix them by -updating software components to newer versions or by applying patches to address them. -It is recommended to work with Poky and OE-Core upstream maintainers and submit -patches to fix them, see :doc:`../contributor-guide/submit-changes` for details. - -Vulnerability check at build time ---------------------------------- - -To enable a check for CVE security vulnerabilities using :ref:`cve-check ` in the specific image -or target you are building, add the following setting to your configuration:: - - INHERIT += "cve-check" - -The CVE database contains some old incomplete entries which have been -deemed not to impact Poky or OE-Core. These CVE entries can be excluded from the -check using build configuration:: - - include conf/distro/include/cve-extra-exclusions.inc - -With this CVE check enabled, BitBake build will try to map each compiled software component -recipe name and version information to the CVE database and generate recipe and -image specific reports. These reports will contain: - -- metadata about the software component like names and versions - -- metadata about the CVE issue such as description and NVD link - -- for each software component, a list of CVEs which are possibly impacting this version - -- status of each CVE: ``Patched``, ``Unpatched`` or ``Ignored`` - -The status ``Patched`` means that a patch file to address the security issue has been -applied. ``Unpatched`` status means that no patches to address the issue have been -applied and that the issue needs to be investigated. ``Ignored`` means that after -analysis, it has been deemed to ignore the issue as it for example affects -the software component on a different operating system platform. - -After a build with CVE check enabled, reports for each compiled source recipe will be -found in ``build/tmp/deploy/cve``. - -For example the CVE check report for the ``flex-native`` recipe looks like:: - - $ cat poky/build/tmp/deploy/cve/flex-native - LAYER: meta - PACKAGE NAME: flex-native - PACKAGE VERSION: 2.6.4 - CVE: CVE-2016-6354 - CVE STATUS: Patched - CVE SUMMARY: Heap-based buffer overflow in the yy_get_next_buffer function in Flex before 2.6.1 might allow context-dependent attackers to cause a denial of service or possibly execute arbitrary code via vectors involving num_to_read. - CVSS v2 BASE SCORE: 7.5 - CVSS v3 BASE SCORE: 9.8 - VECTOR: NETWORK - MORE INFORMATION: https://nvd.nist.gov/vuln/detail/CVE-2016-6354 - - LAYER: meta - PACKAGE NAME: flex-native - PACKAGE VERSION: 2.6.4 - CVE: CVE-2019-6293 - CVE STATUS: Ignored - CVE SUMMARY: An issue was discovered in the function mark_beginning_as_normal in nfa.c in flex 2.6.4. There is a stack exhaustion problem caused by the mark_beginning_as_normal function making recursive calls to itself in certain scenarios involving lots of '*' characters. Remote attackers could leverage this vulnerability to cause a denial-of-service. - CVSS v2 BASE SCORE: 4.3 - CVSS v3 BASE SCORE: 5.5 - VECTOR: NETWORK - MORE INFORMATION: https://nvd.nist.gov/vuln/detail/CVE-2019-6293 - -For images, a summary of all recipes included in the image and their CVEs is also -generated in textual and JSON formats. These ``.cve`` and ``.json`` reports can be found -in the ``tmp/deploy/images`` directory for each compiled image. - -At build time CVE check will also throw warnings about ``Unpatched`` CVEs:: - - WARNING: flex-2.6.4-r0 do_cve_check: Found unpatched CVE (CVE-2019-6293), for more information check /poky/build/tmp/work/core2-64-poky-linux/flex/2.6.4-r0/temp/cve.log - WARNING: libarchive-3.5.1-r0 do_cve_check: Found unpatched CVE (CVE-2021-36976), for more information check /poky/build/tmp/work/core2-64-poky-linux/libarchive/3.5.1-r0/temp/cve.log - -It is also possible to check the CVE status of individual packages as follows:: - - bitbake -c cve_check flex libarchive - -Fixing CVE product name and version mappings --------------------------------------------- - -By default, :ref:`cve-check ` uses the recipe name :term:`BPN` as CVE -product name when querying the CVE database. If this mapping contains false positives, e.g. -some reported CVEs are not for the software component in question, or false negatives like -some CVEs are not found to impact the recipe when they should, then the problems can be -in the recipe name to CVE product mapping. These mapping issues can be fixed by setting -the :term:`CVE_PRODUCT` variable inside the recipe. This defines the name of the software component in the -upstream `NIST CVE database `__. - -The variable supports using vendor and product names like this:: - - CVE_PRODUCT = "flex_project:flex" - -In this example the vendor name used in the CVE database is ``flex_project`` and the -product is ``flex``. With this setting the ``flex`` recipe only maps to this specific -product and not products from other vendors with same name ``flex``. - -Similarly, when the recipe version :term:`PV` is not compatible with software versions used by -the upstream software component releases and the CVE database, these can be fixed using -the :term:`CVE_VERSION` variable. - -Note that if the CVE entries in the NVD database contain bugs or have missing or incomplete -information, it is recommended to fix the information there directly instead of working -around the issues possibly for a long time in Poky and OE-Core side recipes. Feedback to -NVD about CVE entries can be provided through the `NVD contact form `__. - -Fixing vulnerabilities in recipes ---------------------------------- - -If a CVE security issue impacts a software component, it can be fixed by updating to a newer -version of the software component or by applying a patch. For Poky and OE-Core master branches, updating -to a newer software component release with fixes is the best option, but patches can be applied -if releases are not yet available. - -For stable branches, it is preferred to apply patches for the issues. For some software -components minor version updates can also be applied if they are backwards compatible. - -Here is an example of fixing CVE security issues with patch files, -an example from the :oe_layerindex:`ffmpeg recipe`:: - - SRC_URI = "https://www.ffmpeg.org/releases/${BP}.tar.xz \ - file://0001-libavutil-include-assembly-with-full-path-from-sourc.patch \ - file://fix-CVE-2020-20446.patch \ - file://fix-CVE-2020-20453.patch \ - file://fix-CVE-2020-22015.patch \ - file://fix-CVE-2020-22021.patch \ - file://fix-CVE-2020-22033-CVE-2020-22019.patch \ - file://fix-CVE-2021-33815.patch \ - -A good practice is to include the CVE identifier in both the patch file name -and inside the patch file commit message using the format:: - - CVE: CVE-2020-22033 - -CVE checker will then capture this information and change the CVE status to ``Patched`` -in the generated reports. - -If analysis shows that the CVE issue does not impact the recipe due to configuration, platform, -version or other reasons, the CVE can be marked as ``Ignored`` using the :term:`CVE_CHECK_IGNORE` variable. -As mentioned previously, if data in the CVE database is wrong, it is recommend to fix those -issues in the CVE database directly. - -Recipes can be completely skipped by CVE check by including the recipe name in -the :term:`CVE_CHECK_SKIP_RECIPE` variable. - -Implementation details ----------------------- - -Here's what the :ref:`cve-check ` class does to -find unpatched CVE IDs. - -First the code goes through each patch file provided by a recipe. If a valid CVE ID -is found in the name of the file, the corresponding CVE is considered as patched. -Don't forget that if multiple CVE IDs are found in the filename, only the last -one is considered. Then, the code looks for ``CVE: CVE-ID`` lines in the patch -file. The found CVE IDs are also considered as patched. - -Then, the code looks up all the CVE IDs in the NIST database for all the -products defined in :term:`CVE_PRODUCT`. Then, for each found CVE: - -- If the package name (:term:`PN`) is part of - :term:`CVE_CHECK_SKIP_RECIPE`, it is considered as ``Patched``. - -- If the CVE ID is part of :term:`CVE_CHECK_IGNORE`, it is - set as ``Ignored``. - -- If the CVE ID is part of the patched CVE for the recipe, it is - already considered as ``Patched``. - -- Otherwise, the code checks whether the recipe version (:term:`PV`) - is within the range of versions impacted by the CVE. If so, the CVE - is considered as ``Unpatched``. - -The CVE database is stored in :term:`DL_DIR` and can be inspected using -``sqlite3`` command as follows:: - - sqlite3 downloads/CVE_CHECK/nvdcve_1.1.db .dump | grep CVE-2021-37462 - -When analyzing CVEs, it is recommended to: - -- study the latest information in `CVE database `__. - -- check how upstream developers of the software component addressed the issue, e.g. - what patch was applied, which upstream release contains the fix. - -- check what other Linux distributions like `Debian `__ - did to analyze and address the issue. - -- follow security notices from other Linux distributions. - -- follow public `open source security mailing lists `__ for - discussions and advance notifications of CVE bugs and software releases with fixes. - -Creating a Software Bill of Materials -===================================== - -Once you are able to build an image for your project, once the licenses for -each software component are all identified (see -":ref:`dev-manual/common-tasks:working with licenses`") and once vulnerability -fixes are applied (see ":ref:`dev-manual/common-tasks:checking -for vulnerabilities`"), the OpenEmbedded build system can generate -a description of all the components you used, their licenses, their dependencies, -the changes that were applied and the known vulnerabilities that were fixed. - -This description is generated in the form of a *Software Bill of Materials* -(:term:`SBOM`), using the :term:`SPDX` standard. - -When you release software, this is the most standard way to provide information -about the Software Supply Chain of your software image and SDK. The -:term:`SBOM` tooling is often used to ensure open source license compliance by -providing the license texts used in the product which legal departments and end -users can read in standardized format. - -:term:`SBOM` information is also critical to performing vulnerability exposure -assessments, as all the components used in the Software Supply Chain are listed. - -The OpenEmbedded build system doesn't generate such information by default. -To make this happen, you must inherit the -:ref:`create-spdx ` class from a configuration file:: - - INHERIT += "create-spdx" - -You then get :term:`SPDX` output in JSON format as an -``IMAGE-MACHINE.spdx.json`` file in ``tmp/deploy/images/MACHINE/`` inside the -:term:`Build Directory`. - -This is a toplevel file accompanied by an ``IMAGE-MACHINE.spdx.index.json`` -containing an index of JSON :term:`SPDX` files for individual recipes, together -with an ``IMAGE-MACHINE.spdx.tar.zst`` compressed archive containing all such -files. - -The :ref:`ref-classes-create-spdx` class offers options to include -more information in the output :term:`SPDX` data, such as making the generated -files more human readable (:term:`SPDX_PRETTY`), adding compressed archives of -the files in the generated target packages (:term:`SPDX_ARCHIVE_PACKAGED`), -adding a description of the source files used to generate host tools and target -packages (:term:`SPDX_INCLUDE_SOURCES`) and adding archives of these source -files themselves (:term:`SPDX_ARCHIVE_SOURCES`). - -Though the toplevel :term:`SPDX` output is available in -``tmp/deploy/images/MACHINE/`` inside the :term:`Build Directory`, ancillary -generated files are available in ``tmp/deploy/spdx/MACHINE`` too, such as: - -- The individual :term:`SPDX` JSON files in the ``IMAGE-MACHINE.spdx.tar.zst`` - archive. - -- Compressed archives of the files in the generated target packages, - in ``packages/packagename.tar.zst`` (when :term:`SPDX_ARCHIVE_PACKAGED` - is set). - -- Compressed archives of the source files used to build the host tools - and the target packages in ``recipes/recipe-packagename.tar.zst`` - (when :term:`SPDX_ARCHIVE_SOURCES` is set). Those are needed to fulfill - "source code access" license requirements. - -See the `tools page `__ on the :term:`SPDX` -project website for a list of tools to consume and transform the :term:`SPDX` -data generated by the OpenEmbedded build system. - -See also Joshua Watt's -`Automated SBoM generation with OpenEmbedded and the Yocto Project `__ -presentation at FOSDEM 2023. - - -Using the Error Reporting Tool -============================== - -The error reporting tool allows you to submit errors encountered during -builds to a central database. Outside of the build environment, you can -use a web interface to browse errors, view statistics, and query for -errors. The tool works using a client-server system where the client -portion is integrated with the installed Yocto Project -:term:`Source Directory` (e.g. ``poky``). -The server receives the information collected and saves it in a -database. - -There is a live instance of the error reporting server at -https://errors.yoctoproject.org. -When you want to get help with build failures, you can submit all of the -information on the failure easily and then point to the URL in your bug -report or send an email to the mailing list. - -.. note:: - - If you send error reports to this server, the reports become publicly - visible. - -Enabling and Using the Tool ---------------------------- - -By default, the error reporting tool is disabled. You can enable it by -inheriting the -:ref:`report-error ` -class by adding the following statement to the end of your -``local.conf`` file in your -:term:`Build Directory`. -:: - - INHERIT += "report-error" - -By default, the error reporting feature stores information in -``${``\ :term:`LOG_DIR`\ ``}/error-report``. -However, you can specify a directory to use by adding the following to -your ``local.conf`` file:: - - ERR_REPORT_DIR = "path" - -Enabling error -reporting causes the build process to collect the errors and store them -in a file as previously described. When the build system encounters an -error, it includes a command as part of the console output. You can run -the command to send the error file to the server. For example, the -following command sends the errors to an upstream server:: - - $ send-error-report /home/brandusa/project/poky/build/tmp/log/error-report/error_report_201403141617.txt - -In the previous example, the errors are sent to a public database -available at https://errors.yoctoproject.org, which is used by the -entire community. If you specify a particular server, you can send the -errors to a different database. Use the following command for more -information on available options:: - - $ send-error-report --help - -When sending the error file, you are prompted to review the data being -sent as well as to provide a name and optional email address. Once you -satisfy these prompts, the command returns a link from the server that -corresponds to your entry in the database. For example, here is a -typical link: https://errors.yoctoproject.org/Errors/Details/9522/ - -Following the link takes you to a web interface where you can browse, -query the errors, and view statistics. - -Disabling the Tool ------------------- - -To disable the error reporting feature, simply remove or comment out the -following statement from the end of your ``local.conf`` file in your -:term:`Build Directory`. -:: - - INHERIT += "report-error" - -Setting Up Your Own Error Reporting Server ------------------------------------------- - -If you want to set up your own error reporting server, you can obtain -the code from the Git repository at :yocto_git:`/error-report-web/`. -Instructions on how to set it up are in the README document. - -Using Wayland and Weston -======================== - -`Wayland `__ -is a computer display server protocol that provides a method for -compositing window managers to communicate directly with applications -and video hardware and expects them to communicate with input hardware -using other libraries. Using Wayland with supporting targets can result -in better control over graphics frame rendering than an application -might otherwise achieve. - -The Yocto Project provides the Wayland protocol libraries and the -reference -`Weston `__ -compositor as part of its release. You can find the integrated packages -in the ``meta`` layer of the :term:`Source Directory`. -Specifically, you -can find the recipes that build both Wayland and Weston at -``meta/recipes-graphics/wayland``. - -You can build both the Wayland and Weston packages for use only with -targets that accept the `Mesa 3D and Direct Rendering -Infrastructure `__, -which is also known as Mesa DRI. This implies that you cannot build and -use the packages if your target uses, for example, the Intel Embedded -Media and Graphics Driver (Intel EMGD) that overrides Mesa DRI. - -.. note:: - - Due to lack of EGL support, Weston 1.0.3 will not run directly on the - emulated QEMU hardware. However, this version of Weston will run - under X emulation without issues. - -This section describes what you need to do to implement Wayland and use -the Weston compositor when building an image for a supporting target. - -Enabling Wayland in an Image ----------------------------- - -To enable Wayland, you need to enable it to be built and enable it to be -included (installed) in the image. - -Building Wayland -~~~~~~~~~~~~~~~~ - -To cause Mesa to build the ``wayland-egl`` platform and Weston to build -Wayland with Kernel Mode Setting -(`KMS `__) -support, include the "wayland" flag in the -:term:`DISTRO_FEATURES` -statement in your ``local.conf`` file:: - - DISTRO_FEATURES:append = " wayland" - -.. note:: - - If X11 has been enabled elsewhere, Weston will build Wayland with X11 - support - -Installing Wayland and Weston -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -To install the Wayland feature into an image, you must include the -following -:term:`CORE_IMAGE_EXTRA_INSTALL` -statement in your ``local.conf`` file:: - - CORE_IMAGE_EXTRA_INSTALL += "wayland weston" - -Running Weston --------------- - -To run Weston inside X11, enabling it as described earlier and building -a Sato image is sufficient. If you are running your image under Sato, a -Weston Launcher appears in the "Utility" category. - -Alternatively, you can run Weston through the command-line interpretor -(CLI), which is better suited for development work. To run Weston under -the CLI, you need to do the following after your image is built: - -1. Run these commands to export ``XDG_RUNTIME_DIR``:: - - mkdir -p /tmp/$USER-weston - chmod 0700 /tmp/$USER-weston - export XDG_RUNTIME_DIR=/tmp/$USER-weston - -2. Launch Weston in the shell:: - - weston diff --git a/documentation/dev-manual/custom-distribution.rst b/documentation/dev-manual/custom-distribution.rst new file mode 100644 index 0000000000..47faed0d04 --- /dev/null +++ b/documentation/dev-manual/custom-distribution.rst @@ -0,0 +1,109 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Creating Your Own Distribution +****************************** + +When you build an image using the Yocto Project and do not alter any +distribution :term:`Metadata`, you are +creating a Poky distribution. If you wish to gain more control over +package alternative selections, compile-time options, and other +low-level configurations, you can create your own distribution. + +To create your own distribution, the basic steps consist of creating +your own distribution layer, creating your own distribution +configuration file, and then adding any needed code and Metadata to the +layer. The following steps provide some more detail: + +- *Create a layer for your new distro:* Create your distribution layer + so that you can keep your Metadata and code for the distribution + separate. It is strongly recommended that you create and use your own + layer for configuration and code. Using your own layer as compared to + just placing configurations in a ``local.conf`` configuration file + makes it easier to reproduce the same build configuration when using + multiple build machines. See the + ":ref:`dev-manual/layers:creating a general layer using the \`\`bitbake-layers\`\` script`" + section for information on how to quickly set up a layer. + +- *Create the distribution configuration file:* The distribution + configuration file needs to be created in the ``conf/distro`` + directory of your layer. You need to name it using your distribution + name (e.g. ``mydistro.conf``). + + .. note:: + + The :term:`DISTRO` variable in your ``local.conf`` file determines the + name of your distribution. + + You can split out parts of your configuration file into include files + and then "require" them from within your distribution configuration + file. Be sure to place the include files in the + ``conf/distro/include`` directory of your layer. A common example + usage of include files would be to separate out the selection of + desired version and revisions for individual recipes. + + Your configuration file needs to set the following required + variables: + + - :term:`DISTRO_NAME` + + - :term:`DISTRO_VERSION` + + These following variables are optional and you typically set them + from the distribution configuration file: + + - :term:`DISTRO_FEATURES` + + - :term:`DISTRO_EXTRA_RDEPENDS` + + - :term:`DISTRO_EXTRA_RRECOMMENDS` + + - :term:`TCLIBC` + + .. tip:: + + If you want to base your distribution configuration file on the + very basic configuration from OE-Core, you can use + ``conf/distro/defaultsetup.conf`` as a reference and just include + variables that differ as compared to ``defaultsetup.conf``. + Alternatively, you can create a distribution configuration file + from scratch using the ``defaultsetup.conf`` file or configuration files + from another distribution such as Poky as a reference. + +- *Provide miscellaneous variables:* Be sure to define any other + variables for which you want to create a default or enforce as part + of the distribution configuration. You can include nearly any + variable from the ``local.conf`` file. The variables you use are not + limited to the list in the previous bulleted item. + +- *Point to Your distribution configuration file:* In your ``local.conf`` + file in the :term:`Build Directory`, set your :term:`DISTRO` variable to + point to your distribution's configuration file. For example, if your + distribution's configuration file is named ``mydistro.conf``, then + you point to it as follows:: + + DISTRO = "mydistro" + +- *Add more to the layer if necessary:* Use your layer to hold other + information needed for the distribution: + + - Add recipes for installing distro-specific configuration files + that are not already installed by another recipe. If you have + distro-specific configuration files that are included by an + existing recipe, you should add an append file (``.bbappend``) for + those. For general information and recommendations on how to add + recipes to your layer, see the + ":ref:`dev-manual/layers:creating your own layer`" and + ":ref:`dev-manual/layers:following best practices when creating layers`" + sections. + + - Add any image recipes that are specific to your distribution. + + - Add a ``psplash`` append file for a branded splash screen, using + the :term:`SPLASH_IMAGES` variable. + + - Add any other append files to make custom changes that are + specific to individual recipes. + + For information on append files, see the + ":ref:`dev-manual/layers:appending other layers metadata with your layer`" + section. diff --git a/documentation/dev-manual/custom-template-configuration-directory.rst b/documentation/dev-manual/custom-template-configuration-directory.rst new file mode 100644 index 0000000000..90ed3ed92e --- /dev/null +++ b/documentation/dev-manual/custom-template-configuration-directory.rst @@ -0,0 +1,72 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Creating a Custom Template Configuration Directory +************************************************** + +If you are producing your own customized version of the build system for +use by other users, you might want to customize the message shown by the +setup script or you might want to change the template configuration +files (i.e. ``local.conf`` and ``bblayers.conf``) that are created in a +new build directory. + +The OpenEmbedded build system uses the environment variable +``TEMPLATECONF`` to locate the directory from which it gathers +configuration information that ultimately ends up in the +:term:`Build Directory` ``conf`` directory. +By default, ``TEMPLATECONF`` is set as follows in the ``poky`` +repository:: + + TEMPLATECONF=${TEMPLATECONF:-meta-poky/conf} + +This is the +directory used by the build system to find templates from which to build +some key configuration files. If you look at this directory, you will +see the ``bblayers.conf.sample``, ``local.conf.sample``, and +``conf-notes.txt`` files. The build system uses these files to form the +respective ``bblayers.conf`` file, ``local.conf`` file, and display the +list of BitBake targets when running the setup script. + +To override these default configuration files with configurations you +want used within every new Build Directory, simply set the +``TEMPLATECONF`` variable to your directory. The ``TEMPLATECONF`` +variable is set in the ``.templateconf`` file, which is in the top-level +:term:`Source Directory` folder +(e.g. ``poky``). Edit the ``.templateconf`` so that it can locate your +directory. + +Best practices dictate that you should keep your template configuration +directory in your custom distribution layer. For example, suppose you +have a layer named ``meta-mylayer`` located in your home directory and +you want your template configuration directory named ``myconf``. +Changing the ``.templateconf`` as follows causes the OpenEmbedded build +system to look in your directory and base its configuration files on the +``*.sample`` configuration files it finds. The final configuration files +(i.e. ``local.conf`` and ``bblayers.conf`` ultimately still end up in +your Build Directory, but they are based on your ``*.sample`` files. +:: + + TEMPLATECONF=${TEMPLATECONF:-meta-mylayer/myconf} + +Aside from the ``*.sample`` configuration files, the ``conf-notes.txt`` +also resides in the default ``meta-poky/conf`` directory. The script +that sets up the build environment (i.e. +:ref:`structure-core-script`) uses this file to +display BitBake targets as part of the script output. Customizing this +``conf-notes.txt`` file is a good way to make sure your list of custom +targets appears as part of the script's output. + +Here is the default list of targets displayed as a result of running +either of the setup scripts:: + + You can now run 'bitbake ' + + Common targets are: + core-image-minimal + core-image-sato + meta-toolchain + meta-ide-support + +Changing the listed common targets is as easy as editing your version of +``conf-notes.txt`` in your custom template configuration directory and +making sure you have ``TEMPLATECONF`` set to your directory. + diff --git a/documentation/dev-manual/customizing-images.rst b/documentation/dev-manual/customizing-images.rst new file mode 100644 index 0000000000..17dd2d2b0c --- /dev/null +++ b/documentation/dev-manual/customizing-images.rst @@ -0,0 +1,223 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Customizing Images +****************** + +You can customize images to satisfy particular requirements. This +section describes several methods and provides guidelines for each. + +Customizing Images Using ``local.conf`` +======================================= + +Probably the easiest way to customize an image is to add a package by +way of the ``local.conf`` configuration file. Because it is limited to +local use, this method generally only allows you to add packages and is +not as flexible as creating your own customized image. When you add +packages using local variables this way, you need to realize that these +variable changes are in effect for every build and consequently affect +all images, which might not be what you require. + +To add a package to your image using the local configuration file, use +the :term:`IMAGE_INSTALL` variable with the ``:append`` operator:: + + IMAGE_INSTALL:append = " strace" + +Use of the syntax is important; specifically, the leading space +after the opening quote and before the package name, which is +``strace`` in this example. This space is required since the ``:append`` +operator does not add the space. + +Furthermore, you must use ``:append`` instead of the ``+=`` operator if +you want to avoid ordering issues. The reason for this is because doing +so unconditionally appends to the variable and avoids ordering problems +due to the variable being set in image recipes and ``.bbclass`` files +with operators like ``?=``. Using ``:append`` ensures the operation +takes effect. + +As shown in its simplest use, ``IMAGE_INSTALL:append`` affects all +images. It is possible to extend the syntax so that the variable applies +to a specific image only. Here is an example:: + + IMAGE_INSTALL:append:pn-core-image-minimal = " strace" + +This example adds ``strace`` to the ``core-image-minimal`` image only. + +You can add packages using a similar approach through the +:term:`CORE_IMAGE_EXTRA_INSTALL` variable. If you use this variable, only +``core-image-*`` images are affected. + +Customizing Images Using Custom ``IMAGE_FEATURES`` and ``EXTRA_IMAGE_FEATURES`` +=============================================================================== + +Another method for customizing your image is to enable or disable +high-level image features by using the +:term:`IMAGE_FEATURES` and +:term:`EXTRA_IMAGE_FEATURES` +variables. Although the functions for both variables are nearly +equivalent, best practices dictate using :term:`IMAGE_FEATURES` from within +a recipe and using :term:`EXTRA_IMAGE_FEATURES` from within your +``local.conf`` file, which is found in the :term:`Build Directory`. + +To understand how these features work, the best reference is +:ref:`meta/classes/image.bbclass `. +This class lists out the available +:term:`IMAGE_FEATURES` of which most map to package groups while some, such +as ``debug-tweaks`` and ``read-only-rootfs``, resolve as general +configuration settings. + +In summary, the file looks at the contents of the :term:`IMAGE_FEATURES` +variable and then maps or configures the feature accordingly. Based on +this information, the build system automatically adds the appropriate +packages or configurations to the +:term:`IMAGE_INSTALL` variable. +Effectively, you are enabling extra features by extending the class or +creating a custom class for use with specialized image ``.bb`` files. + +Use the :term:`EXTRA_IMAGE_FEATURES` variable from within your local +configuration file. Using a separate area from which to enable features +with this variable helps you avoid overwriting the features in the image +recipe that are enabled with :term:`IMAGE_FEATURES`. The value of +:term:`EXTRA_IMAGE_FEATURES` is added to :term:`IMAGE_FEATURES` within +``meta/conf/bitbake.conf``. + +To illustrate how you can use these variables to modify your image, +consider an example that selects the SSH server. The Yocto Project ships +with two SSH servers you can use with your images: Dropbear and OpenSSH. +Dropbear is a minimal SSH server appropriate for resource-constrained +environments, while OpenSSH is a well-known standard SSH server +implementation. By default, the ``core-image-sato`` image is configured +to use Dropbear. The ``core-image-full-cmdline`` and ``core-image-lsb`` +images both include OpenSSH. The ``core-image-minimal`` image does not +contain an SSH server. + +You can customize your image and change these defaults. Edit the +:term:`IMAGE_FEATURES` variable in your recipe or use the +:term:`EXTRA_IMAGE_FEATURES` in your ``local.conf`` file so that it +configures the image you are working with to include +``ssh-server-dropbear`` or ``ssh-server-openssh``. + +.. note:: + + See the ":ref:`ref-manual/features:image features`" section in the Yocto + Project Reference Manual for a complete list of image features that ship + with the Yocto Project. + +Customizing Images Using Custom .bb Files +========================================= + +You can also customize an image by creating a custom recipe that defines +additional software as part of the image. The following example shows +the form for the two lines you need:: + + IMAGE_INSTALL = "packagegroup-core-x11-base package1 package2" + inherit core-image + +Defining the software using a custom recipe gives you total control over +the contents of the image. It is important to use the correct names of +packages in the :term:`IMAGE_INSTALL` variable. You must use the +OpenEmbedded notation and not the Debian notation for the names (e.g. +``glibc-dev`` instead of ``libc6-dev``). + +The other method for creating a custom image is to base it on an +existing image. For example, if you want to create an image based on +``core-image-sato`` but add the additional package ``strace`` to the +image, copy the ``meta/recipes-sato/images/core-image-sato.bb`` to a new +``.bb`` and add the following line to the end of the copy:: + + IMAGE_INSTALL += "strace" + +Customizing Images Using Custom Package Groups +============================================== + +For complex custom images, the best approach for customizing an image is +to create a custom package group recipe that is used to build the image +or images. A good example of a package group recipe is +``meta/recipes-core/packagegroups/packagegroup-base.bb``. + +If you examine that recipe, you see that the :term:`PACKAGES` variable lists +the package group packages to produce. The ``inherit packagegroup`` +statement sets appropriate default values and automatically adds +``-dev``, ``-dbg``, and ``-ptest`` complementary packages for each +package specified in the :term:`PACKAGES` statement. + +.. note:: + + The ``inherit packagegroup`` line should be located near the top of the + recipe, certainly before the :term:`PACKAGES` statement. + +For each package you specify in :term:`PACKAGES`, you can use :term:`RDEPENDS` +and :term:`RRECOMMENDS` entries to provide a list of packages the parent +task package should contain. You can see examples of these further down +in the ``packagegroup-base.bb`` recipe. + +Here is a short, fabricated example showing the same basic pieces for a +hypothetical packagegroup defined in ``packagegroup-custom.bb``, where +the variable :term:`PN` is the standard way to abbreviate the reference to +the full packagegroup name ``packagegroup-custom``:: + + DESCRIPTION = "My Custom Package Groups" + + inherit packagegroup + + PACKAGES = "\ + ${PN}-apps \ + ${PN}-tools \ + " + + RDEPENDS:${PN}-apps = "\ + dropbear \ + portmap \ + psplash" + + RDEPENDS:${PN}-tools = "\ + oprofile \ + oprofileui-server \ + lttng-tools" + + RRECOMMENDS:${PN}-tools = "\ + kernel-module-oprofile" + +In the previous example, two package group packages are created with +their dependencies and their recommended package dependencies listed: +``packagegroup-custom-apps``, and ``packagegroup-custom-tools``. To +build an image using these package group packages, you need to add +``packagegroup-custom-apps`` and/or ``packagegroup-custom-tools`` to +:term:`IMAGE_INSTALL`. For other forms of image dependencies see the other +areas of this section. + +Customizing an Image Hostname +============================= + +By default, the configured hostname (i.e. ``/etc/hostname``) in an image +is the same as the machine name. For example, if +:term:`MACHINE` equals "qemux86", the +configured hostname written to ``/etc/hostname`` is "qemux86". + +You can customize this name by altering the value of the "hostname" +variable in the ``base-files`` recipe using either an append file or a +configuration file. Use the following in an append file:: + + hostname = "myhostname" + +Use the following in a configuration file:: + + hostname:pn-base-files = "myhostname" + +Changing the default value of the variable "hostname" can be useful in +certain situations. For example, suppose you need to do extensive +testing on an image and you would like to easily identify the image +under test from existing images with typical default hostnames. In this +situation, you could change the default hostname to "testme", which +results in all the images using the name "testme". Once testing is +complete and you do not need to rebuild the image for test any longer, +you can easily reset the default hostname. + +Another point of interest is that if you unset the variable, the image +will have no default hostname in the filesystem. Here is an example that +unsets the variable in a configuration file:: + + hostname:pn-base-files = "" + +Having no default hostname in the filesystem is suitable for +environments that use dynamic hostnames such as virtual machines. + diff --git a/documentation/dev-manual/debugging.rst b/documentation/dev-manual/debugging.rst new file mode 100644 index 0000000000..fea2cb30a1 --- /dev/null +++ b/documentation/dev-manual/debugging.rst @@ -0,0 +1,1245 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Debugging Tools and Techniques +****************************** + +The exact method for debugging build failures depends on the nature of +the problem and on the system's area from which the bug originates. +Standard debugging practices such as comparison against the last known +working version with examination of the changes and the re-application +of steps to identify the one causing the problem are valid for the Yocto +Project just as they are for any other system. Even though it is +impossible to detail every possible potential failure, this section +provides some general tips to aid in debugging given a variety of +situations. + +.. note:: + + A useful feature for debugging is the error reporting tool. + Configuring the Yocto Project to use this tool causes the + OpenEmbedded build system to produce error reporting commands as part + of the console output. You can enter the commands after the build + completes to log error information into a common database, that can + help you figure out what might be going wrong. For information on how + to enable and use this feature, see the + ":ref:`dev-manual/error-reporting-tool:using the error reporting tool`" + section. + +The following list shows the debugging topics in the remainder of this +section: + +- ":ref:`dev-manual/debugging:viewing logs from failed tasks`" describes + how to find and view logs from tasks that failed during the build + process. + +- ":ref:`dev-manual/debugging:viewing variable values`" describes how to + use the BitBake ``-e`` option to examine variable values after a + recipe has been parsed. + +- ":ref:`dev-manual/debugging:viewing package information with \`\`oe-pkgdata-util\`\``" + describes how to use the ``oe-pkgdata-util`` utility to query + :term:`PKGDATA_DIR` and + display package-related information for built packages. + +- ":ref:`dev-manual/debugging:viewing dependencies between recipes and tasks`" + describes how to use the BitBake ``-g`` option to display recipe + dependency information used during the build. + +- ":ref:`dev-manual/debugging:viewing task variable dependencies`" describes + how to use the ``bitbake-dumpsig`` command in conjunction with key + subdirectories in the :term:`Build Directory` to determine variable + dependencies. + +- ":ref:`dev-manual/debugging:running specific tasks`" describes + how to use several BitBake options (e.g. ``-c``, ``-C``, and ``-f``) + to run specific tasks in the build chain. It can be useful to run + tasks "out-of-order" when trying isolate build issues. + +- ":ref:`dev-manual/debugging:general BitBake problems`" describes how + to use BitBake's ``-D`` debug output option to reveal more about what + BitBake is doing during the build. + +- ":ref:`dev-manual/debugging:building with no dependencies`" + describes how to use the BitBake ``-b`` option to build a recipe + while ignoring dependencies. + +- ":ref:`dev-manual/debugging:recipe logging mechanisms`" + describes how to use the many recipe logging functions to produce + debugging output and report errors and warnings. + +- ":ref:`dev-manual/debugging:debugging parallel make races`" + describes how to debug situations where the build consists of several + parts that are run simultaneously and when the output or result of + one part is not ready for use with a different part of the build that + depends on that output. + +- ":ref:`dev-manual/debugging:debugging with the gnu project debugger (gdb) remotely`" + describes how to use GDB to allow you to examine running programs, which can + help you fix problems. + +- ":ref:`dev-manual/debugging:debugging with the gnu project debugger (gdb) on the target`" + describes how to use GDB directly on target hardware for debugging. + +- ":ref:`dev-manual/debugging:other debugging tips`" describes + miscellaneous debugging tips that can be useful. + +Viewing Logs from Failed Tasks +============================== + +You can find the log for a task in the file +``${``\ :term:`WORKDIR`\ ``}/temp/log.do_``\ `taskname`. +For example, the log for the +:ref:`ref-tasks-compile` task of the +QEMU minimal image for the x86 machine (``qemux86``) might be in +``tmp/work/qemux86-poky-linux/core-image-minimal/1.0-r0/temp/log.do_compile``. +To see the commands :term:`BitBake` ran +to generate a log, look at the corresponding ``run.do_``\ `taskname` file +in the same directory. + +``log.do_``\ `taskname` and ``run.do_``\ `taskname` are actually symbolic +links to ``log.do_``\ `taskname`\ ``.``\ `pid` and +``log.run_``\ `taskname`\ ``.``\ `pid`, where `pid` is the PID the task had +when it ran. The symlinks always point to the files corresponding to the +most recent run. + +Viewing Variable Values +======================= + +Sometimes you need to know the value of a variable as a result of +BitBake's parsing step. This could be because some unexpected behavior +occurred in your project. Perhaps an attempt to :ref:`modify a variable +` did not work out as expected. + +BitBake's ``-e`` option is used to display variable values after +parsing. The following command displays the variable values after the +configuration files (i.e. ``local.conf``, ``bblayers.conf``, +``bitbake.conf`` and so forth) have been parsed:: + + $ bitbake -e + +The following command displays variable values after a specific recipe has +been parsed. The variables include those from the configuration as well:: + + $ bitbake -e recipename + +.. note:: + + Each recipe has its own private set of variables (datastore). + Internally, after parsing the configuration, a copy of the resulting + datastore is made prior to parsing each recipe. This copying implies + that variables set in one recipe will not be visible to other + recipes. + + Likewise, each task within a recipe gets a private datastore based on + the recipe datastore, which means that variables set within one task + will not be visible to other tasks. + +In the output of ``bitbake -e``, each variable is preceded by a +description of how the variable got its value, including temporary +values that were later overridden. This description also includes +variable flags (varflags) set on the variable. The output can be very +helpful during debugging. + +Variables that are exported to the environment are preceded by +``export`` in the output of ``bitbake -e``. See the following example:: + + export CC="i586-poky-linux-gcc -m32 -march=i586 --sysroot=/home/ulf/poky/build/tmp/sysroots/qemux86" + +In addition to variable values, the output of the ``bitbake -e`` and +``bitbake -e`` recipe commands includes the following information: + +- The output starts with a tree listing all configuration files and + classes included globally, recursively listing the files they include + or inherit in turn. Much of the behavior of the OpenEmbedded build + system (including the behavior of the :ref:`ref-manual/tasks:normal recipe build tasks`) is + implemented in the :ref:`ref-classes-base` class and the + classes it inherits, rather than being built into BitBake itself. + +- After the variable values, all functions appear in the output. For + shell functions, variables referenced within the function body are + expanded. If a function has been modified using overrides or using + override-style operators like ``:append`` and ``:prepend``, then the + final assembled function body appears in the output. + +Viewing Package Information with ``oe-pkgdata-util`` +==================================================== + +You can use the ``oe-pkgdata-util`` command-line utility to query +:term:`PKGDATA_DIR` and display +various package-related information. When you use the utility, you must +use it to view information on packages that have already been built. + +Following are a few of the available ``oe-pkgdata-util`` subcommands. + +.. note:: + + You can use the standard \* and ? globbing wildcards as part of + package names and paths. + +- ``oe-pkgdata-util list-pkgs [pattern]``: Lists all packages + that have been built, optionally limiting the match to packages that + match pattern. + +- ``oe-pkgdata-util list-pkg-files package ...``: Lists the + files and directories contained in the given packages. + + .. note:: + + A different way to view the contents of a package is to look at + the + ``${``\ :term:`WORKDIR`\ ``}/packages-split`` + directory of the recipe that generates the package. This directory + is created by the + :ref:`ref-tasks-package` task + and has one subdirectory for each package the recipe generates, + which contains the files stored in that package. + + If you want to inspect the ``${WORKDIR}/packages-split`` + directory, make sure that :ref:`ref-classes-rm-work` is not + enabled when you build the recipe. + +- ``oe-pkgdata-util find-path path ...``: Lists the names of + the packages that contain the given paths. For example, the following + tells us that ``/usr/share/man/man1/make.1`` is contained in the + ``make-doc`` package:: + + $ oe-pkgdata-util find-path /usr/share/man/man1/make.1 + make-doc: /usr/share/man/man1/make.1 + +- ``oe-pkgdata-util lookup-recipe package ...``: Lists the name + of the recipes that produce the given packages. + +For more information on the ``oe-pkgdata-util`` command, use the help +facility:: + + $ oe-pkgdata-util --help + $ oe-pkgdata-util subcommand --help + +Viewing Dependencies Between Recipes and Tasks +============================================== + +Sometimes it can be hard to see why BitBake wants to build other recipes +before the one you have specified. Dependency information can help you +understand why a recipe is built. + +To generate dependency information for a recipe, run the following +command:: + + $ bitbake -g recipename + +This command writes the following files in the current directory: + +- ``pn-buildlist``: A list of recipes/targets involved in building + `recipename`. "Involved" here means that at least one task from the + recipe needs to run when building `recipename` from scratch. Targets + that are in + :term:`ASSUME_PROVIDED` + are not listed. + +- ``task-depends.dot``: A graph showing dependencies between tasks. + +The graphs are in :wikipedia:`DOT ` +format and can be converted to images (e.g. using the ``dot`` tool from +`Graphviz `__). + +.. note:: + + - DOT files use a plain text format. The graphs generated using the + ``bitbake -g`` command are often so large as to be difficult to + read without special pruning (e.g. with BitBake's ``-I`` option) + and processing. Despite the form and size of the graphs, the + corresponding ``.dot`` files can still be possible to read and + provide useful information. + + As an example, the ``task-depends.dot`` file contains lines such + as the following:: + + "libxslt.do_configure" -> "libxml2.do_populate_sysroot" + + The above example line reveals that the + :ref:`ref-tasks-configure` + task in ``libxslt`` depends on the + :ref:`ref-tasks-populate_sysroot` + task in ``libxml2``, which is a normal + :term:`DEPENDS` dependency + between the two recipes. + + - For an example of how ``.dot`` files can be processed, see the + ``scripts/contrib/graph-tool`` Python script, which finds and + displays paths between graph nodes. + +You can use a different method to view dependency information by using +the following command:: + + $ bitbake -g -u taskexp recipename + +This command +displays a GUI window from which you can view build-time and runtime +dependencies for the recipes involved in building recipename. + +Viewing Task Variable Dependencies +================================== + +As mentioned in the +":ref:`bitbake-user-manual/bitbake-user-manual-execution:checksums (signatures)`" +section of the BitBake User Manual, BitBake tries to automatically determine +what variables a task depends on so that it can rerun the task if any values of +the variables change. This determination is usually reliable. However, if you +do things like construct variable names at runtime, then you might have to +manually declare dependencies on those variables using ``vardeps`` as described +in the ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:variable flags`" +section of the BitBake User Manual. + +If you are unsure whether a variable dependency is being picked up +automatically for a given task, you can list the variable dependencies +BitBake has determined by doing the following: + +#. Build the recipe containing the task:: + + $ bitbake recipename + +#. Inside the :term:`STAMPS_DIR` + directory, find the signature data (``sigdata``) file that + corresponds to the task. The ``sigdata`` files contain a pickled + Python database of all the metadata that went into creating the input + checksum for the task. As an example, for the + :ref:`ref-tasks-fetch` task of the + ``db`` recipe, the ``sigdata`` file might be found in the following + location:: + + ${BUILDDIR}/tmp/stamps/i586-poky-linux/db/6.0.30-r1.do_fetch.sigdata.7c048c18222b16ff0bcee2000ef648b1 + + For tasks that are accelerated through the shared state + (:ref:`sstate `) cache, an + additional ``siginfo`` file is written into + :term:`SSTATE_DIR` along with + the cached task output. The ``siginfo`` files contain exactly the + same information as ``sigdata`` files. + +#. Run ``bitbake-dumpsig`` on the ``sigdata`` or ``siginfo`` file. Here + is an example:: + + $ bitbake-dumpsig ${BUILDDIR}/tmp/stamps/i586-poky-linux/db/6.0.30-r1.do_fetch.sigdata.7c048c18222b16ff0bcee2000ef648b1 + + In the output of the above command, you will find a line like the + following, which lists all the (inferred) variable dependencies for + the task. This list also includes indirect dependencies from + variables depending on other variables, recursively:: + + Task dependencies: ['PV', 'SRCREV', 'SRC_URI', 'SRC_URI[md5sum]', 'SRC_URI[sha256sum]', 'base_do_fetch'] + + .. note:: + + Functions (e.g. ``base_do_fetch``) also count as variable dependencies. + These functions in turn depend on the variables they reference. + + The output of ``bitbake-dumpsig`` also includes the value each + variable had, a list of dependencies for each variable, and + :term:`BB_BASEHASH_IGNORE_VARS` + information. + +There is also a ``bitbake-diffsigs`` command for comparing two +``siginfo`` or ``sigdata`` files. This command can be helpful when +trying to figure out what changed between two versions of a task. If you +call ``bitbake-diffsigs`` with just one file, the command behaves like +``bitbake-dumpsig``. + +You can also use BitBake to dump out the signature construction +information without executing tasks by using either of the following +BitBake command-line options:: + + ‐‐dump-signatures=SIGNATURE_HANDLER + -S SIGNATURE_HANDLER + + +.. note:: + + Two common values for `SIGNATURE_HANDLER` are "none" and "printdiff", which + dump only the signature or compare the dumped signature with the cached one, + respectively. + +Using BitBake with either of these options causes BitBake to dump out +``sigdata`` files in the ``stamps`` directory for every task it would +have executed instead of building the specified target package. + +Viewing Metadata Used to Create the Input Signature of a Shared State Task +========================================================================== + +Seeing what metadata went into creating the input signature of a shared +state (sstate) task can be a useful debugging aid. This information is +available in signature information (``siginfo``) files in +:term:`SSTATE_DIR`. For +information on how to view and interpret information in ``siginfo`` +files, see the +":ref:`dev-manual/debugging:viewing task variable dependencies`" section. + +For conceptual information on shared state, see the +":ref:`overview-manual/concepts:shared state`" +section in the Yocto Project Overview and Concepts Manual. + +Invalidating Shared State to Force a Task to Run +================================================ + +The OpenEmbedded build system uses +:ref:`checksums ` and +:ref:`overview-manual/concepts:shared state` cache to avoid unnecessarily +rebuilding tasks. Collectively, this scheme is known as "shared state +code". + +As with all schemes, this one has some drawbacks. It is possible that +you could make implicit changes to your code that the checksum +calculations do not take into account. These implicit changes affect a +task's output but do not trigger the shared state code into rebuilding a +recipe. Consider an example during which a tool changes its output. +Assume that the output of ``rpmdeps`` changes. The result of the change +should be that all the ``package`` and ``package_write_rpm`` shared +state cache items become invalid. However, because the change to the +output is external to the code and therefore implicit, the associated +shared state cache items do not become invalidated. In this case, the +build process uses the cached items rather than running the task again. +Obviously, these types of implicit changes can cause problems. + +To avoid these problems during the build, you need to understand the +effects of any changes you make. Realize that changes you make directly +to a function are automatically factored into the checksum calculation. +Thus, these explicit changes invalidate the associated area of shared +state cache. However, you need to be aware of any implicit changes that +are not obvious changes to the code and could affect the output of a +given task. + +When you identify an implicit change, you can easily take steps to +invalidate the cache and force the tasks to run. The steps you can take +are as simple as changing a function's comments in the source code. For +example, to invalidate package shared state files, change the comment +statements of +:ref:`ref-tasks-package` or the +comments of one of the functions it calls. Even though the change is +purely cosmetic, it causes the checksum to be recalculated and forces +the build system to run the task again. + +.. note:: + + For an example of a commit that makes a cosmetic change to invalidate + shared state, see this + :yocto_git:`commit `. + +Running Specific Tasks +====================== + +Any given recipe consists of a set of tasks. The standard BitBake +behavior in most cases is: :ref:`ref-tasks-fetch`, :ref:`ref-tasks-unpack`, :ref:`ref-tasks-patch`, +:ref:`ref-tasks-configure`, :ref:`ref-tasks-compile`, :ref:`ref-tasks-install`, :ref:`ref-tasks-package`, +:ref:`do_package_write_* `, and :ref:`ref-tasks-build`. The default task is +:ref:`ref-tasks-build` and any tasks on which it depends build first. Some tasks, +such as :ref:`ref-tasks-devshell`, are not part of the default build chain. If you +wish to run a task that is not part of the default build chain, you can +use the ``-c`` option in BitBake. Here is an example:: + + $ bitbake matchbox-desktop -c devshell + +The ``-c`` option respects task dependencies, which means that all other +tasks (including tasks from other recipes) that the specified task +depends on will be run before the task. Even when you manually specify a +task to run with ``-c``, BitBake will only run the task if it considers +it "out of date". See the +":ref:`overview-manual/concepts:stamp files and the rerunning of tasks`" +section in the Yocto Project Overview and Concepts Manual for how +BitBake determines whether a task is "out of date". + +If you want to force an up-to-date task to be rerun (e.g. because you +made manual modifications to the recipe's +:term:`WORKDIR` that you want to try +out), then you can use the ``-f`` option. + +.. note:: + + The reason ``-f`` is never required when running the + :ref:`ref-tasks-devshell` task is because the + [\ :ref:`nostamp `\ ] + variable flag is already set for the task. + +The following example shows one way you can use the ``-f`` option:: + + $ bitbake matchbox-desktop + . + . + make some changes to the source code in the work directory + . + . + $ bitbake matchbox-desktop -c compile -f + $ bitbake matchbox-desktop + +This sequence first builds and then recompiles ``matchbox-desktop``. The +last command reruns all tasks (basically the packaging tasks) after the +compile. BitBake recognizes that the :ref:`ref-tasks-compile` task was rerun and +therefore understands that the other tasks also need to be run again. + +Another, shorter way to rerun a task and all +:ref:`ref-manual/tasks:normal recipe build tasks` +that depend on it is to use the ``-C`` option. + +.. note:: + + This option is upper-cased and is separate from the ``-c`` + option, which is lower-cased. + +Using this option invalidates the given task and then runs the +:ref:`ref-tasks-build` task, which is +the default task if no task is given, and the tasks on which it depends. +You could replace the final two commands in the previous example with +the following single command:: + + $ bitbake matchbox-desktop -C compile + +Internally, the ``-f`` and ``-C`` options work by tainting (modifying) +the input checksum of the specified task. This tainting indirectly +causes the task and its dependent tasks to be rerun through the normal +task dependency mechanisms. + +.. note:: + + BitBake explicitly keeps track of which tasks have been tainted in + this fashion, and will print warnings such as the following for + builds involving such tasks: + + .. code-block:: none + + WARNING: /home/ulf/poky/meta/recipes-sato/matchbox-desktop/matchbox-desktop_2.1.bb.do_compile is tainted from a forced run + + + The purpose of the warning is to let you know that the work directory + and build output might not be in the clean state they would be in for + a "normal" build, depending on what actions you took. To get rid of + such warnings, you can remove the work directory and rebuild the + recipe, as follows:: + + $ bitbake matchbox-desktop -c clean + $ bitbake matchbox-desktop + + +You can view a list of tasks in a given package by running the +:ref:`ref-tasks-listtasks` task as follows:: + + $ bitbake matchbox-desktop -c listtasks + +The results appear as output to the console and are also in +the file ``${WORKDIR}/temp/log.do_listtasks``. + +General BitBake Problems +======================== + +You can see debug output from BitBake by using the ``-D`` option. The +debug output gives more information about what BitBake is doing and the +reason behind it. Each ``-D`` option you use increases the logging +level. The most common usage is ``-DDD``. + +The output from ``bitbake -DDD -v targetname`` can reveal why BitBake +chose a certain version of a package or why BitBake picked a certain +provider. This command could also help you in a situation where you +think BitBake did something unexpected. + +Building with No Dependencies +============================= + +To build a specific recipe (``.bb`` file), you can use the following +command form:: + + $ bitbake -b somepath/somerecipe.bb + +This command form does +not check for dependencies. Consequently, you should use it only when +you know existing dependencies have been met. + +.. note:: + + You can also specify fragments of the filename. In this case, BitBake + checks for a unique match. + +Recipe Logging Mechanisms +========================= + +The Yocto Project provides several logging functions for producing +debugging output and reporting errors and warnings. For Python +functions, the following logging functions are available. All of these functions +log to ``${T}/log.do_``\ `task`, and can also log to standard output +(stdout) with the right settings: + +- ``bb.plain(msg)``: Writes msg as is to the log while also + logging to stdout. + +- ``bb.note(msg)``: Writes "NOTE: msg" to the log. Also logs to + stdout if BitBake is called with "-v". + +- ``bb.debug(level, msg)``: Writes "DEBUG: msg" to the log. Also logs to + stdout if the log level is greater than or equal to level. See the + ":ref:`bitbake-user-manual/bitbake-user-manual-intro:usage and syntax`" + option in the BitBake User Manual for more information. + +- ``bb.warn(msg)``: Writes "WARNING: msg" to the log while also + logging to stdout. + +- ``bb.error(msg)``: Writes "ERROR: msg" to the log while also + logging to standard out (stdout). + + .. note:: + + Calling this function does not cause the task to fail. + +- ``bb.fatal(msg)``: This logging function is similar to + ``bb.error(msg)`` but also causes the calling task to fail. + + .. note:: + + ``bb.fatal()`` raises an exception, which means you do not need to put a + "return" statement after the function. + +The same logging functions are also available in shell functions, under +the names ``bbplain``, ``bbnote``, ``bbdebug``, ``bbwarn``, ``bberror``, +and ``bbfatal``. The :ref:`ref-classes-logging` class +implements these functions. See that class in the ``meta/classes`` +folder of the :term:`Source Directory` for information. + +Logging With Python +------------------- + +When creating recipes using Python and inserting code that handles build +logs, keep in mind the goal is to have informative logs while keeping +the console as "silent" as possible. Also, if you want status messages +in the log, use the "debug" loglevel. + +Following is an example written in Python. The code handles logging for +a function that determines the number of tasks needed to be run. See the +":ref:`ref-tasks-listtasks`" +section for additional information:: + + python do_listtasks() { + bb.debug(2, "Starting to figure out the task list") + if noteworthy_condition: + bb.note("There are 47 tasks to run") + bb.debug(2, "Got to point xyz") + if warning_trigger: + bb.warn("Detected warning_trigger, this might be a problem later.") + if recoverable_error: + bb.error("Hit recoverable_error, you really need to fix this!") + if fatal_error: + bb.fatal("fatal_error detected, unable to print the task list") + bb.plain("The tasks present are abc") + bb.debug(2, "Finished figuring out the tasklist") + } + +Logging With Bash +----------------- + +When creating recipes using Bash and inserting code that handles build +logs, you have the same goals --- informative with minimal console output. +The syntax you use for recipes written in Bash is similar to that of +recipes written in Python described in the previous section. + +Following is an example written in Bash. The code logs the progress of +the ``do_my_function`` function:: + + do_my_function() { + bbdebug 2 "Running do_my_function" + if [ exceptional_condition ]; then + bbnote "Hit exceptional_condition" + fi + bbdebug 2 "Got to point xyz" + if [ warning_trigger ]; then + bbwarn "Detected warning_trigger, this might cause a problem later." + fi + if [ recoverable_error ]; then + bberror "Hit recoverable_error, correcting" + fi + if [ fatal_error ]; then + bbfatal "fatal_error detected" + fi + bbdebug 2 "Completed do_my_function" + } + + +Debugging Parallel Make Races +============================= + +A parallel ``make`` race occurs when the build consists of several parts +that are run simultaneously and a situation occurs when the output or +result of one part is not ready for use with a different part of the +build that depends on that output. Parallel make races are annoying and +can sometimes be difficult to reproduce and fix. However, there are some simple +tips and tricks that can help you debug and fix them. This section +presents a real-world example of an error encountered on the Yocto +Project autobuilder and the process used to fix it. + +.. note:: + + If you cannot properly fix a ``make`` race condition, you can work around it + by clearing either the :term:`PARALLEL_MAKE` or :term:`PARALLEL_MAKEINST` + variables. + +The Failure +----------- + +For this example, assume that you are building an image that depends on +the "neard" package. And, during the build, BitBake runs into problems +and creates the following output. + +.. note:: + + This example log file has longer lines artificially broken to make + the listing easier to read. + +If you examine the output or the log file, you see the failure during +``make``: + +.. code-block:: none + + | DEBUG: SITE files ['endian-little', 'bit-32', 'ix86-common', 'common-linux', 'common-glibc', 'i586-linux', 'common'] + | DEBUG: Executing shell function do_compile + | NOTE: make -j 16 + | make --no-print-directory all-am + | /bin/mkdir -p include/near + | /bin/mkdir -p include/near + | /bin/mkdir -p include/near + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/types.h include/near/types.h + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/log.h include/near/log.h + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/plugin.h include/near/plugin.h + | /bin/mkdir -p include/near + | /bin/mkdir -p include/near + | /bin/mkdir -p include/near + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/tag.h include/near/tag.h + | /bin/mkdir -p include/near + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/adapter.h include/near/adapter.h + | /bin/mkdir -p include/near + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/ndef.h include/near/ndef.h + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/tlv.h include/near/tlv.h + | /bin/mkdir -p include/near + | /bin/mkdir -p include/near + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/setting.h include/near/setting.h + | /bin/mkdir -p include/near + | /bin/mkdir -p include/near + | /bin/mkdir -p include/near + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/device.h include/near/device.h + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/nfc_copy.h include/near/nfc_copy.h + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/snep.h include/near/snep.h + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/version.h include/near/version.h + | ln -s /home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/work/i586-poky-linux/neard/ + 0.14-r0/neard-0.14/include/dbus.h include/near/dbus.h + | ./src/genbuiltin nfctype1 nfctype2 nfctype3 nfctype4 p2p > src/builtin.h + | i586-poky-linux-gcc -m32 -march=i586 --sysroot=/home/pokybuild/yocto-autobuilder/nightly-x86/ + build/build/tmp/sysroots/qemux86 -DHAVE_CONFIG_H -I. -I./include -I./src -I./gdbus -I/home/pokybuild/ + yocto-autobuilder/nightly-x86/build/build/tmp/sysroots/qemux86/usr/include/glib-2.0 + -I/home/pokybuild/yocto-autobuilder/nightly-x86/build/build/tmp/sysroots/qemux86/usr/ + lib/glib-2.0/include -I/home/pokybuild/yocto-autobuilder/nightly-x86/build/build/ + tmp/sysroots/qemux86/usr/include/dbus-1.0 -I/home/pokybuild/yocto-autobuilder/ + nightly-x86/build/build/tmp/sysroots/qemux86/usr/lib/dbus-1.0/include -I/home/pokybuild/yocto-autobuilder/ + nightly-x86/build/build/tmp/sysroots/qemux86/usr/include/libnl3 + -DNEAR_PLUGIN_BUILTIN -DPLUGINDIR=\""/usr/lib/near/plugins"\" + -DCONFIGDIR=\""/etc/neard\"" -O2 -pipe -g -feliminate-unused-debug-types -c + -o tools/snep-send.o tools/snep-send.c + | In file included from tools/snep-send.c:16:0: + | tools/../src/near.h:41:23: fatal error: near/dbus.h: No such file or directory + | #include + | ^ + | compilation terminated. + | make[1]: *** [tools/snep-send.o] Error 1 + | make[1]: *** Waiting for unfinished jobs.... + | make: *** [all] Error 2 + | ERROR: oe_runmake failed + +Reproducing the Error +--------------------- + +Because race conditions are intermittent, they do not manifest +themselves every time you do the build. In fact, most times the build +will complete without problems even though the potential race condition +exists. Thus, once the error surfaces, you need a way to reproduce it. + +In this example, compiling the "neard" package is causing the problem. +So the first thing to do is build "neard" locally. Before you start the +build, set the +:term:`PARALLEL_MAKE` variable +in your ``local.conf`` file to a high number (e.g. "-j 20"). Using a +high value for :term:`PARALLEL_MAKE` increases the chances of the race +condition showing up:: + + $ bitbake neard + +Once the local build for "neard" completes, start a ``devshell`` build:: + + $ bitbake neard -c devshell + +For information on how to use a ``devshell``, see the +":ref:`dev-manual/development-shell:using a development shell`" section. + +In the ``devshell``, do the following:: + + $ make clean + $ make tools/snep-send.o + +The ``devshell`` commands cause the failure to clearly +be visible. In this case, there is a missing dependency for the ``neard`` +Makefile target. Here is some abbreviated, sample output with the +missing dependency clearly visible at the end:: + + i586-poky-linux-gcc -m32 -march=i586 --sysroot=/home/scott-lenovo/...... + . + . + . + tools/snep-send.c + In file included from tools/snep-send.c:16:0: + tools/../src/near.h:41:23: fatal error: near/dbus.h: No such file or directory + #include + ^ + compilation terminated. + make: *** [tools/snep-send.o] Error 1 + $ + + +Creating a Patch for the Fix +---------------------------- + +Because there is a missing dependency for the Makefile target, you need +to patch the ``Makefile.am`` file, which is generated from +``Makefile.in``. You can use Quilt to create the patch:: + + $ quilt new parallelmake.patch + Patch patches/parallelmake.patch is now on top + $ quilt add Makefile.am + File Makefile.am added to patch patches/parallelmake.patch + +For more information on using Quilt, see the +":ref:`dev-manual/quilt:using quilt in your workflow`" section. + +At this point you need to make the edits to ``Makefile.am`` to add the +missing dependency. For our example, you have to add the following line +to the file:: + + tools/snep-send.$(OBJEXT): include/near/dbus.h + +Once you have edited the file, use the ``refresh`` command to create the +patch:: + + $ quilt refresh + Refreshed patch patches/parallelmake.patch + +Once the patch file is created, you need to add it back to the originating +recipe folder. Here is an example assuming a top-level +:term:`Source Directory` named ``poky``:: + + $ cp patches/parallelmake.patch poky/meta/recipes-connectivity/neard/neard + +The final thing you need to do to implement the fix in the build is to +update the "neard" recipe (i.e. ``neard-0.14.bb``) so that the +:term:`SRC_URI` statement includes +the patch file. The recipe file is in the folder above the patch. Here +is what the edited :term:`SRC_URI` statement would look like:: + + SRC_URI = "${KERNELORG_MIRROR}/linux/network/nfc/${BPN}-${PV}.tar.xz \ + file://neard.in \ + file://neard.service.in \ + file://parallelmake.patch \ + " + +With the patch complete and moved to the correct folder and the +:term:`SRC_URI` statement updated, you can exit the ``devshell``:: + + $ exit + +Testing the Build +----------------- + +With everything in place, you can get back to trying the build again +locally:: + + $ bitbake neard + +This build should succeed. + +Now you can open up a ``devshell`` again and repeat the clean and make +operations as follows:: + + $ bitbake neard -c devshell + $ make clean + $ make tools/snep-send.o + +The build should work without issue. + +As with all solved problems, if they originated upstream, you need to +submit the fix for the recipe in OE-Core and upstream so that the +problem is taken care of at its source. See the +":doc:`../contributor-guide/submit-changes`" section for more information. + +Debugging With the GNU Project Debugger (GDB) Remotely +====================================================== + +GDB allows you to examine running programs, which in turn helps you to +understand and fix problems. It also allows you to perform post-mortem +style analysis of program crashes. GDB is available as a package within +the Yocto Project and is installed in SDK images by default. See the +":ref:`ref-manual/images:Images`" chapter in the Yocto +Project Reference Manual for a description of these images. You can find +information on GDB at https://sourceware.org/gdb/. + +.. note:: + + For best results, install debug (``-dbg``) packages for the applications you + are going to debug. Doing so makes extra debug symbols available that give + you more meaningful output. + +Sometimes, due to memory or disk space constraints, it is not possible +to use GDB directly on the remote target to debug applications. These +constraints arise because GDB needs to load the debugging information +and the binaries of the process being debugged. Additionally, GDB needs +to perform many computations to locate information such as function +names, variable names and values, stack traces and so forth --- even +before starting the debugging process. These extra computations place +more load on the target system and can alter the characteristics of the +program being debugged. + +To help get past the previously mentioned constraints, there are two +methods you can use: running a debuginfod server and using gdbserver. + +Using the debuginfod server method +---------------------------------- + +``debuginfod`` from ``elfutils`` is a way to distribute ``debuginfo`` files. +Running a ``debuginfod`` server makes debug symbols readily available, +which means you don't need to download debugging information +and the binaries of the process being debugged. You can just fetch +debug symbols from the server. + +To run a ``debuginfod`` server, you need to do the following: + +- Ensure that ``debuginfod`` is present in :term:`DISTRO_FEATURES` + (it already is in ``OpenEmbedded-core`` defaults and ``poky`` reference distribution). + If not, set in your distro config file or in ``local.conf``:: + + DISTRO_FEATURES:append = " debuginfod" + + This distro feature enables the server and client library in ``elfutils``, + and enables ``debuginfod`` support in clients (at the moment, ``gdb`` and ``binutils``). + +- Run the following commands to launch the ``debuginfod`` server on the host:: + + $ oe-debuginfod + +- To use ``debuginfod`` on the target, you need to know the ip:port where + ``debuginfod`` is listening on the host (port defaults to 8002), and export + that into the shell environment, for example in ``qemu``:: + + root@qemux86-64:~# export DEBUGINFOD_URLS="http://192.168.7.1:8002/" + +- Then debug info fetching should simply work when running the target ``gdb``, + ``readelf`` or ``objdump``, for example:: + + root@qemux86-64:~# gdb /bin/cat + ... + Reading symbols from /bin/cat... + Downloading separate debug info for /bin/cat... + Reading symbols from /home/root/.cache/debuginfod_client/923dc4780cfbc545850c616bffa884b6b5eaf322/debuginfo... + +- It's also possible to use ``debuginfod-find`` to just query the server:: + + root@qemux86-64:~# debuginfod-find debuginfo /bin/ls + /home/root/.cache/debuginfod_client/356edc585f7f82d46f94fcb87a86a3fe2d2e60bd/debuginfo + + +Using the gdbserver method +-------------------------- + +gdbserver, which runs on the remote target and does not load any +debugging information from the debugged process. Instead, a GDB instance +processes the debugging information that is run on a remote computer - +the host GDB. The host GDB then sends control commands to gdbserver to +make it stop or start the debugged program, as well as read or write +memory regions of that debugged program. All the debugging information +loaded and processed as well as all the heavy debugging is done by the +host GDB. Offloading these processes gives the gdbserver running on the +target a chance to remain small and fast. + +Because the host GDB is responsible for loading the debugging +information and for doing the necessary processing to make actual +debugging happen, you have to make sure the host can access the +unstripped binaries complete with their debugging information and also +be sure the target is compiled with no optimizations. The host GDB must +also have local access to all the libraries used by the debugged +program. Because gdbserver does not need any local debugging +information, the binaries on the remote target can remain stripped. +However, the binaries must also be compiled without optimization so they +match the host's binaries. + +To remain consistent with GDB documentation and terminology, the binary +being debugged on the remote target machine is referred to as the +"inferior" binary. For documentation on GDB see the `GDB +site `__. + +The following steps show you how to debug using the GNU project +debugger. + +#. *Configure your build system to construct the companion debug + filesystem:* + + In your ``local.conf`` file, set the following:: + + IMAGE_GEN_DEBUGFS = "1" + IMAGE_FSTYPES_DEBUGFS = "tar.bz2" + + These options cause the + OpenEmbedded build system to generate a special companion filesystem + fragment, which contains the matching source and debug symbols to + your deployable filesystem. The build system does this by looking at + what is in the deployed filesystem, and pulling the corresponding + ``-dbg`` packages. + + The companion debug filesystem is not a complete filesystem, but only + contains the debug fragments. This filesystem must be combined with + the full filesystem for debugging. Subsequent steps in this procedure + show how to combine the partial filesystem with the full filesystem. + +#. *Configure the system to include gdbserver in the target filesystem:* + + Make the following addition in your ``local.conf`` file:: + + EXTRA_IMAGE_FEATURES:append = " tools-debug" + + The change makes + sure the ``gdbserver`` package is included. + +#. *Build the environment:* + + Use the following command to construct the image and the companion + Debug Filesystem:: + + $ bitbake image + + Build the cross GDB component and + make it available for debugging. Build the SDK that matches the + image. Building the SDK is best for a production build that can be + used later for debugging, especially during long term maintenance:: + + $ bitbake -c populate_sdk image + + Alternatively, you can build the minimal toolchain components that + match the target. Doing so creates a smaller than typical SDK and + only contains a minimal set of components with which to build simple + test applications, as well as run the debugger:: + + $ bitbake meta-toolchain + + A final method is to build Gdb itself within the build system:: + + $ bitbake gdb-cross- + + Doing so produces a temporary copy of + ``cross-gdb`` you can use for debugging during development. While + this is the quickest approach, the two previous methods in this step + are better when considering long-term maintenance strategies. + + .. note:: + + If you run ``bitbake gdb-cross``, the OpenEmbedded build system suggests + the actual image (e.g. ``gdb-cross-i586``). The suggestion is usually the + actual name you want to use. + +#. *Set up the* ``debugfs``\ *:* + + Run the following commands to set up the ``debugfs``:: + + $ mkdir debugfs + $ cd debugfs + $ tar xvfj build-dir/tmp/deploy/images/machine/image.rootfs.tar.bz2 + $ tar xvfj build-dir/tmp/deploy/images/machine/image-dbg.rootfs.tar.bz2 + +#. *Set up GDB:* + + Install the SDK (if you built one) and then source the correct + environment file. Sourcing the environment file puts the SDK in your + ``PATH`` environment variable and sets ``$GDB`` to the SDK's debugger. + + If you are using the build system, Gdb is located in + `build-dir`\ ``/tmp/sysroots/``\ `host`\ ``/usr/bin/``\ `architecture`\ ``/``\ `architecture`\ ``-gdb`` + +#. *Boot the target:* + + For information on how to run QEMU, see the `QEMU + Documentation `__. + + .. note:: + + Be sure to verify that your host can access the target via TCP. + +#. *Debug a program:* + + Debugging a program involves running gdbserver on the target and then + running Gdb on the host. The example in this step debugs ``gzip``: + + .. code-block:: shell + + root@qemux86:~# gdbserver localhost:1234 /bin/gzip —help + + For + additional gdbserver options, see the `GDB Server + Documentation `__. + + After running gdbserver on the target, you need to run Gdb on the + host and configure it and connect to the target. Use these commands:: + + $ cd directory-holding-the-debugfs-directory + $ arch-gdb + (gdb) set sysroot debugfs + (gdb) set substitute-path /usr/src/debug debugfs/usr/src/debug + (gdb) target remote IP-of-target:1234 + + At this + point, everything should automatically load (i.e. matching binaries, + symbols and headers). + + .. note:: + + The Gdb ``set`` commands in the previous example can be placed into the + users ``~/.gdbinit`` file. Upon starting, Gdb automatically runs whatever + commands are in that file. + +#. *Deploying without a full image rebuild:* + + In many cases, during development you want a quick method to deploy a + new binary to the target and debug it, without waiting for a full + image build. + + One approach to solving this situation is to just build the component + you want to debug. Once you have built the component, copy the + executable directly to both the target and the host ``debugfs``. + + If the binary is processed through the debug splitting in + OpenEmbedded, you should also copy the debug items (i.e. ``.debug`` + contents and corresponding ``/usr/src/debug`` files) from the work + directory. Here is an example:: + + $ bitbake bash + $ bitbake -c devshell bash + $ cd .. + $ scp packages-split/bash/bin/bash target:/bin/bash + $ cp -a packages-split/bash-dbg/\* path/debugfs + +Debugging with the GNU Project Debugger (GDB) on the Target +=========================================================== + +The previous section addressed using GDB remotely for debugging +purposes, which is the most usual case due to the inherent hardware +limitations on many embedded devices. However, debugging in the target +hardware itself is also possible with more powerful devices. This +section describes what you need to do in order to support using GDB to +debug on the target hardware. + +To support this kind of debugging, you need do the following: + +- Ensure that GDB is on the target. You can do this by making + the following addition to your ``local.conf`` file:: + + EXTRA_IMAGE_FEATURES:append = " tools-debug" + +- Ensure that debug symbols are present. You can do so by adding the + corresponding ``-dbg`` package to :term:`IMAGE_INSTALL`:: + + IMAGE_INSTALL:append = " packagename-dbg" + + Alternatively, you can add the following to ``local.conf`` to include + all the debug symbols:: + + EXTRA_IMAGE_FEATURES:append = " dbg-pkgs" + +.. note:: + + To improve the debug information accuracy, you can reduce the level + of optimization used by the compiler. For example, when adding the + following line to your ``local.conf`` file, you will reduce optimization + from :term:`FULL_OPTIMIZATION` of "-O2" to :term:`DEBUG_OPTIMIZATION` + of "-O -fno-omit-frame-pointer":: + + DEBUG_BUILD = "1" + + Consider that this will reduce the application's performance and is + recommended only for debugging purposes. + +Other Debugging Tips +==================== + +Here are some other tips that you might find useful: + +- When adding new packages, it is worth watching for undesirable items + making their way into compiler command lines. For example, you do not + want references to local system files like ``/usr/lib/`` or + ``/usr/include/``. + +- If you want to remove the ``psplash`` boot splashscreen, add + ``psplash=false`` to the kernel command line. Doing so prevents + ``psplash`` from loading and thus allows you to see the console. It + is also possible to switch out of the splashscreen by switching the + virtual console (e.g. Fn+Left or Fn+Right on a Zaurus). + +- Removing :term:`TMPDIR` (usually ``tmp/``, within the + :term:`Build Directory`) can often fix temporary build issues. Removing + :term:`TMPDIR` is usually a relatively cheap operation, because task output + will be cached in :term:`SSTATE_DIR` (usually ``sstate-cache/``, which is + also in the :term:`Build Directory`). + + .. note:: + + Removing :term:`TMPDIR` might be a workaround rather than a fix. + Consequently, trying to determine the underlying cause of an issue before + removing the directory is a good idea. + +- Understanding how a feature is used in practice within existing + recipes can be very helpful. It is recommended that you configure + some method that allows you to quickly search through files. + + Using GNU Grep, you can use the following shell function to + recursively search through common recipe-related files, skipping + binary files, ``.git`` directories, and the :term:`Build Directory` + (assuming its name starts with "build"):: + + g() { + grep -Ir \ + --exclude-dir=.git \ + --exclude-dir='build*' \ + --include='*.bb*' \ + --include='*.inc*' \ + --include='*.conf*' \ + --include='*.py*' \ + "$@" + } + + Following are some usage examples:: + + $ g FOO # Search recursively for "FOO" + $ g -i foo # Search recursively for "foo", ignoring case + $ g -w FOO # Search recursively for "FOO" as a word, ignoring e.g. "FOOBAR" + + If figuring + out how some feature works requires a lot of searching, it might + indicate that the documentation should be extended or improved. In + such cases, consider filing a documentation bug using the Yocto + Project implementation of + :yocto_bugs:`Bugzilla <>`. For information on + how to submit a bug against the Yocto Project, see the Yocto Project + Bugzilla :yocto_wiki:`wiki page ` + and the ":doc:`../contributor-guide/report-defect`" section. + + .. note:: + + The manuals might not be the right place to document variables + that are purely internal and have a limited scope (e.g. internal + variables used to implement a single ``.bbclass`` file). + diff --git a/documentation/dev-manual/development-shell.rst b/documentation/dev-manual/development-shell.rst new file mode 100644 index 0000000000..a18d792150 --- /dev/null +++ b/documentation/dev-manual/development-shell.rst @@ -0,0 +1,82 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Using a Development Shell +************************* + +When debugging certain commands or even when just editing packages, +``devshell`` can be a useful tool. When you invoke ``devshell``, all +tasks up to and including +:ref:`ref-tasks-patch` are run for the +specified target. Then, a new terminal is opened and you are placed in +``${``\ :term:`S`\ ``}``, the source +directory. In the new terminal, all the OpenEmbedded build-related +environment variables are still defined so you can use commands such as +``configure`` and ``make``. The commands execute just as if the +OpenEmbedded build system were executing them. Consequently, working +this way can be helpful when debugging a build or preparing software to +be used with the OpenEmbedded build system. + +Following is an example that uses ``devshell`` on a target named +``matchbox-desktop``:: + + $ bitbake matchbox-desktop -c devshell + +This command spawns a terminal with a shell prompt within the +OpenEmbedded build environment. The +:term:`OE_TERMINAL` variable +controls what type of shell is opened. + +For spawned terminals, the following occurs: + +- The ``PATH`` variable includes the cross-toolchain. + +- The ``pkgconfig`` variables find the correct ``.pc`` files. + +- The ``configure`` command finds the Yocto Project site files as well + as any other necessary files. + +Within this environment, you can run configure or compile commands as if +they were being run by the OpenEmbedded build system itself. As noted +earlier, the working directory also automatically changes to the Source +Directory (:term:`S`). + +To manually run a specific task using ``devshell``, run the +corresponding ``run.*`` script in the +``${``\ :term:`WORKDIR`\ ``}/temp`` +directory (e.g., ``run.do_configure.``\ `pid`). If a task's script does +not exist, which would be the case if the task was skipped by way of the +sstate cache, you can create the task by first running it outside of the +``devshell``:: + + $ bitbake -c task + +.. note:: + + - Execution of a task's ``run.*`` script and BitBake's execution of + a task are identical. In other words, running the script re-runs + the task just as it would be run using the ``bitbake -c`` command. + + - Any ``run.*`` file that does not have a ``.pid`` extension is a + symbolic link (symlink) to the most recent version of that file. + +Remember, that the ``devshell`` is a mechanism that allows you to get +into the BitBake task execution environment. And as such, all commands +must be called just as BitBake would call them. That means you need to +provide the appropriate options for cross-compilation and so forth as +applicable. + +When you are finished using ``devshell``, exit the shell or close the +terminal window. + +.. note:: + + - It is worth remembering that when using ``devshell`` you need to + use the full compiler name such as ``arm-poky-linux-gnueabi-gcc`` + instead of just using ``gcc``. The same applies to other + applications such as ``binutils``, ``libtool`` and so forth. + BitBake sets up environment variables such as :term:`CC` to assist + applications, such as ``make`` to find the correct tools. + + - It is also worth noting that ``devshell`` still works over X11 + forwarding and similar situations. + diff --git a/documentation/dev-manual/device-manager.rst b/documentation/dev-manual/device-manager.rst new file mode 100644 index 0000000000..0343d19b9c --- /dev/null +++ b/documentation/dev-manual/device-manager.rst @@ -0,0 +1,74 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +.. _device-manager: + +Selecting a Device Manager +************************** + +The Yocto Project provides multiple ways to manage the device manager +(``/dev``): + +- Persistent and Pre-Populated ``/dev``: For this case, the ``/dev`` + directory is persistent and the required device nodes are created + during the build. + +- Use ``devtmpfs`` with a Device Manager: For this case, the ``/dev`` + directory is provided by the kernel as an in-memory file system and + is automatically populated by the kernel at runtime. Additional + configuration of device nodes is done in user space by a device + manager like ``udev`` or ``busybox-mdev``. + +Using Persistent and Pre-Populated ``/dev`` +=========================================== + +To use the static method for device population, you need to set the +:term:`USE_DEVFS` variable to "0" +as follows:: + + USE_DEVFS = "0" + +The content of the resulting ``/dev`` directory is defined in a Device +Table file. The +:term:`IMAGE_DEVICE_TABLES` +variable defines the Device Table to use and should be set in the +machine or distro configuration file. Alternatively, you can set this +variable in your ``local.conf`` configuration file. + +If you do not define the :term:`IMAGE_DEVICE_TABLES` variable, the default +``device_table-minimal.txt`` is used:: + + IMAGE_DEVICE_TABLES = "device_table-mymachine.txt" + +The population is handled by the ``makedevs`` utility during image +creation: + +Using ``devtmpfs`` and a Device Manager +======================================= + +To use the dynamic method for device population, you need to use (or be +sure to set) the :term:`USE_DEVFS` +variable to "1", which is the default:: + + USE_DEVFS = "1" + +With this +setting, the resulting ``/dev`` directory is populated by the kernel +using ``devtmpfs``. Make sure the corresponding kernel configuration +variable ``CONFIG_DEVTMPFS`` is set when building you build a Linux +kernel. + +All devices created by ``devtmpfs`` will be owned by ``root`` and have +permissions ``0600``. + +To have more control over the device nodes, you can use a device manager +like ``udev`` or ``busybox-mdev``. You choose the device manager by +defining the ``VIRTUAL-RUNTIME_dev_manager`` variable in your machine or +distro configuration file. Alternatively, you can set this variable in +your ``local.conf`` configuration file:: + + VIRTUAL-RUNTIME_dev_manager = "udev" + + # Some alternative values + # VIRTUAL-RUNTIME_dev_manager = "busybox-mdev" + # VIRTUAL-RUNTIME_dev_manager = "systemd" + diff --git a/documentation/dev-manual/disk-space.rst b/documentation/dev-manual/disk-space.rst new file mode 100644 index 0000000000..a84bef4511 --- /dev/null +++ b/documentation/dev-manual/disk-space.rst @@ -0,0 +1,61 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Conserving Disk Space +********************* + +Conserving Disk Space During Builds +=================================== + +To help conserve disk space during builds, you can add the following +statement to your project's ``local.conf`` configuration file found in +the :term:`Build Directory`:: + + INHERIT += "rm_work" + +Adding this statement deletes the work directory used for +building a recipe once the recipe is built. For more information on +"rm_work", see the :ref:`ref-classes-rm-work` class in the +Yocto Project Reference Manual. + +When you inherit this class and build a ``core-image-sato`` image for a +``qemux86-64`` machine from an Ubuntu 22.04 x86-64 system, you end up with a +final disk usage of 22 Gbytes instead of &MIN_DISK_SPACE; Gbytes. However, +&MIN_DISK_SPACE_RM_WORK; Gbytes of initial free disk space are still needed to +create temporary files before they can be deleted. + +Purging Duplicate Shared State Cache Files +========================================== + +After multiple build iterations, the Shared State (sstate) cache can contain +duplicate cache files for a given package, consuming a substantial amount of +disk space. However, only the most recent cache files are likeky to be reusable. + +The following command is a quick way to purge all the cache files which +haven't been used for a least a specified number of days:: + + find build/sstate-cache -type f -mtime +$DAYS -delete + +The above command relies on the fact that BitBake touches the sstate cache +files as it accesses them, when it has write access to the cache. + +You could use ``-atime`` instead of ``-mtime`` if the partition isn't mounted +with the ``noatime`` option for a read only cache. + +For more advanced needs, OpenEmbedded-Core also offers a more elaborate +command. It has the ability to purge all but the newest cache files on each +architecture, and also to remove files that it considers unreachable by +exploring a set of build configurations. However, this command +requires a full build environment to be available and doesn't work well +covering multiple releases. It won't work either on limited environments +such as BSD based NAS:: + + sstate-cache-management.sh --remove-duplicated --cache-dir=build/sstate-cache + +This command will ask you to confirm the deletions it identifies. +Run ``sstate-cache-management.sh`` for more details about this script. + +.. note:: + + As this command is much more cautious and selective, removing only cache files, + it will execute much slower than the simple ``find`` command described above. + Therefore, it may not be your best option to trim huge cache directories. diff --git a/documentation/dev-manual/efficiently-fetching-sources.rst b/documentation/dev-manual/efficiently-fetching-sources.rst new file mode 100644 index 0000000000..fd9ad6aa69 --- /dev/null +++ b/documentation/dev-manual/efficiently-fetching-sources.rst @@ -0,0 +1,68 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Efficiently Fetching Source Files During a Build +================================================ + +The OpenEmbedded build system works with source files located through +the :term:`SRC_URI` variable. When +you build something using BitBake, a big part of the operation is +locating and downloading all the source tarballs. For images, +downloading all the source for various packages can take a significant +amount of time. + +This section shows you how you can use mirrors to speed up fetching +source files and how you can pre-fetch files all of which leads to more +efficient use of resources and time. + +Setting up Effective Mirrors +---------------------------- + +A good deal that goes into a Yocto Project build is simply downloading +all of the source tarballs. Maybe you have been working with another +build system for which you have built up a +sizable directory of source tarballs. Or, perhaps someone else has such +a directory for which you have read access. If so, you can save time by +adding statements to your configuration file so that the build process +checks local directories first for existing tarballs before checking the +Internet. + +Here is an efficient way to set it up in your ``local.conf`` file:: + + SOURCE_MIRROR_URL ?= "file:///home/you/your-download-dir/" + INHERIT += "own-mirrors" + BB_GENERATE_MIRROR_TARBALLS = "1" + # BB_NO_NETWORK = "1" + +In the previous example, the +:term:`BB_GENERATE_MIRROR_TARBALLS` +variable causes the OpenEmbedded build system to generate tarballs of +the Git repositories and store them in the +:term:`DL_DIR` directory. Due to +performance reasons, generating and storing these tarballs is not the +build system's default behavior. + +You can also use the +:term:`PREMIRRORS` variable. For +an example, see the variable's glossary entry in the Yocto Project +Reference Manual. + +Getting Source Files and Suppressing the Build +---------------------------------------------- + +Another technique you can use to ready yourself for a successive string +of build operations, is to pre-fetch all the source files without +actually starting a build. This technique lets you work through any +download issues and ultimately gathers all the source files into your +download directory :ref:`structure-build-downloads`, +which is located with :term:`DL_DIR`. + +Use the following BitBake command form to fetch all the necessary +sources without starting the build:: + + $ bitbake target --runall=fetch + +This +variation of the BitBake command guarantees that you have all the +sources for that BitBake target should you disconnect from the Internet +and want to do the build later offline. + diff --git a/documentation/dev-manual/error-reporting-tool.rst b/documentation/dev-manual/error-reporting-tool.rst new file mode 100644 index 0000000000..84f3d9cd1e --- /dev/null +++ b/documentation/dev-manual/error-reporting-tool.rst @@ -0,0 +1,84 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Using the Error Reporting Tool +****************************** + +The error reporting tool allows you to submit errors encountered during +builds to a central database. Outside of the build environment, you can +use a web interface to browse errors, view statistics, and query for +errors. The tool works using a client-server system where the client +portion is integrated with the installed Yocto Project +:term:`Source Directory` (e.g. ``poky``). +The server receives the information collected and saves it in a +database. + +There is a live instance of the error reporting server at +https://errors.yoctoproject.org. +When you want to get help with build failures, you can submit all of the +information on the failure easily and then point to the URL in your bug +report or send an email to the mailing list. + +.. note:: + + If you send error reports to this server, the reports become publicly + visible. + +Enabling and Using the Tool +=========================== + +By default, the error reporting tool is disabled. You can enable it by +inheriting the :ref:`ref-classes-report-error` class by adding the +following statement to the end of your ``local.conf`` file in your +:term:`Build Directory`:: + + INHERIT += "report-error" + +By default, the error reporting feature stores information in +``${``\ :term:`LOG_DIR`\ ``}/error-report``. +However, you can specify a directory to use by adding the following to +your ``local.conf`` file:: + + ERR_REPORT_DIR = "path" + +Enabling error +reporting causes the build process to collect the errors and store them +in a file as previously described. When the build system encounters an +error, it includes a command as part of the console output. You can run +the command to send the error file to the server. For example, the +following command sends the errors to an upstream server:: + + $ send-error-report /home/brandusa/project/poky/build/tmp/log/error-report/error_report_201403141617.txt + +In the previous example, the errors are sent to a public database +available at https://errors.yoctoproject.org, which is used by the +entire community. If you specify a particular server, you can send the +errors to a different database. Use the following command for more +information on available options:: + + $ send-error-report --help + +When sending the error file, you are prompted to review the data being +sent as well as to provide a name and optional email address. Once you +satisfy these prompts, the command returns a link from the server that +corresponds to your entry in the database. For example, here is a +typical link: https://errors.yoctoproject.org/Errors/Details/9522/ + +Following the link takes you to a web interface where you can browse, +query the errors, and view statistics. + +Disabling the Tool +================== + +To disable the error reporting feature, simply remove or comment out the +following statement from the end of your ``local.conf`` file in your +:term:`Build Directory`:: + + INHERIT += "report-error" + +Setting Up Your Own Error Reporting Server +========================================== + +If you want to set up your own error reporting server, you can obtain +the code from the Git repository at :yocto_git:`/error-report-web/`. +Instructions on how to set it up are in the README document. + diff --git a/documentation/dev-manual/external-scm.rst b/documentation/dev-manual/external-scm.rst new file mode 100644 index 0000000000..97a7e63e36 --- /dev/null +++ b/documentation/dev-manual/external-scm.rst @@ -0,0 +1,67 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Using an External SCM +********************* + +If you're working on a recipe that pulls from an external Source Code +Manager (SCM), it is possible to have the OpenEmbedded build system +notice new recipe changes added to the SCM and then build the resulting +packages that depend on the new recipes by using the latest versions. +This only works for SCMs from which it is possible to get a sensible +revision number for changes. Currently, you can do this with Apache +Subversion (SVN), Git, and Bazaar (BZR) repositories. + +To enable this behavior, the :term:`PV` of +the recipe needs to reference +:term:`SRCPV`. Here is an example:: + + PV = "1.2.3+git${SRCPV}" + +Then, you can add the following to your +``local.conf``:: + + SRCREV:pn-PN = "${AUTOREV}" + +:term:`PN` is the name of the recipe for +which you want to enable automatic source revision updating. + +If you do not want to update your local configuration file, you can add +the following directly to the recipe to finish enabling the feature:: + + SRCREV = "${AUTOREV}" + +The Yocto Project provides a distribution named ``poky-bleeding``, whose +configuration file contains the line:: + + require conf/distro/include/poky-floating-revisions.inc + +This line pulls in the +listed include file that contains numerous lines of exactly that form:: + + #SRCREV:pn-opkg-native ?= "${AUTOREV}" + #SRCREV:pn-opkg-sdk ?= "${AUTOREV}" + #SRCREV:pn-opkg ?= "${AUTOREV}" + #SRCREV:pn-opkg-utils-native ?= "${AUTOREV}" + #SRCREV:pn-opkg-utils ?= "${AUTOREV}" + SRCREV:pn-gconf-dbus ?= "${AUTOREV}" + SRCREV:pn-matchbox-common ?= "${AUTOREV}" + SRCREV:pn-matchbox-config-gtk ?= "${AUTOREV}" + SRCREV:pn-matchbox-desktop ?= "${AUTOREV}" + SRCREV:pn-matchbox-keyboard ?= "${AUTOREV}" + SRCREV:pn-matchbox-panel-2 ?= "${AUTOREV}" + SRCREV:pn-matchbox-themes-extra ?= "${AUTOREV}" + SRCREV:pn-matchbox-terminal ?= "${AUTOREV}" + SRCREV:pn-matchbox-wm ?= "${AUTOREV}" + SRCREV:pn-settings-daemon ?= "${AUTOREV}" + SRCREV:pn-screenshot ?= "${AUTOREV}" + . . . + +These lines allow you to +experiment with building a distribution that tracks the latest +development source for numerous packages. + +.. note:: + + The ``poky-bleeding`` distribution is not tested on a regular basis. Keep + this in mind if you use it. + diff --git a/documentation/dev-manual/external-toolchain.rst b/documentation/dev-manual/external-toolchain.rst new file mode 100644 index 0000000000..238f8cf467 --- /dev/null +++ b/documentation/dev-manual/external-toolchain.rst @@ -0,0 +1,40 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Optionally Using an External Toolchain +************************************** + +You might want to use an external toolchain as part of your development. +If this is the case, the fundamental steps you need to accomplish are as +follows: + +- Understand where the installed toolchain resides. For cases where you + need to build the external toolchain, you would need to take separate + steps to build and install the toolchain. + +- Make sure you add the layer that contains the toolchain to your + ``bblayers.conf`` file through the + :term:`BBLAYERS` variable. + +- Set the :term:`EXTERNAL_TOOLCHAIN` variable in your ``local.conf`` file + to the location in which you installed the toolchain. + +The toolchain configuration is very flexible and customizable. It +is primarily controlled with the :term:`TCMODE` variable. This variable +controls which ``tcmode-*.inc`` file to include from the +``meta/conf/distro/include`` directory within the :term:`Source Directory`. + +The default value of :term:`TCMODE` is "default", which tells the +OpenEmbedded build system to use its internally built toolchain (i.e. +``tcmode-default.inc``). However, other patterns are accepted. In +particular, "external-\*" refers to external toolchains. One example is +the Mentor Graphics Sourcery G++ Toolchain. Support for this toolchain resides +in the separate ``meta-sourcery`` layer at +https://github.com/MentorEmbedded/meta-sourcery/. +See its ``README`` file for details about how to use this layer. + +Another example of external toolchain layer is +:yocto_git:`meta-arm-toolchain ` +supporting GNU toolchains released by ARM. + +You can find further information by reading about the :term:`TCMODE` variable +in the Yocto Project Reference Manual's variable glossary. diff --git a/documentation/dev-manual/gobject-introspection.rst b/documentation/dev-manual/gobject-introspection.rst new file mode 100644 index 0000000000..f7206e6fae --- /dev/null +++ b/documentation/dev-manual/gobject-introspection.rst @@ -0,0 +1,155 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Enabling GObject Introspection Support +************************************** + +`GObject introspection `__ +is the standard mechanism for accessing GObject-based software from +runtime environments. GObject is a feature of the GLib library that +provides an object framework for the GNOME desktop and related software. +GObject Introspection adds information to GObject that allows objects +created within it to be represented across different programming +languages. If you want to construct GStreamer pipelines using Python, or +control UPnP infrastructure using Javascript and GUPnP, GObject +introspection is the only way to do it. + +This section describes the Yocto Project support for generating and +packaging GObject introspection data. GObject introspection data is a +description of the API provided by libraries built on top of the GLib +framework, and, in particular, that framework's GObject mechanism. +GObject Introspection Repository (GIR) files go to ``-dev`` packages, +``typelib`` files go to main packages as they are packaged together with +libraries that are introspected. + +The data is generated when building such a library, by linking the +library with a small executable binary that asks the library to describe +itself, and then executing the binary and processing its output. + +Generating this data in a cross-compilation environment is difficult +because the library is produced for the target architecture, but its +code needs to be executed on the build host. This problem is solved with +the OpenEmbedded build system by running the code through QEMU, which +allows precisely that. Unfortunately, QEMU does not always work +perfectly as mentioned in the ":ref:`dev-manual/gobject-introspection:known issues`" +section. + +Enabling the Generation of Introspection Data +============================================= + +Enabling the generation of introspection data (GIR files) in your +library package involves the following: + +#. Inherit the :ref:`ref-classes-gobject-introspection` class. + +#. Make sure introspection is not disabled anywhere in the recipe or + from anything the recipe includes. Also, make sure that + "gobject-introspection-data" is not in + :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED` + and that "qemu-usermode" is not in + :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`. + In either of these conditions, nothing will happen. + +#. Try to build the recipe. If you encounter build errors that look like + something is unable to find ``.so`` libraries, check where these + libraries are located in the source tree and add the following to the + recipe:: + + GIR_EXTRA_LIBS_PATH = "${B}/something/.libs" + + .. note:: + + See recipes in the ``oe-core`` repository that use that + :term:`GIR_EXTRA_LIBS_PATH` variable as an example. + +#. Look for any other errors, which probably mean that introspection + support in a package is not entirely standard, and thus breaks down + in a cross-compilation environment. For such cases, custom-made fixes + are needed. A good place to ask and receive help in these cases is + the :ref:`Yocto Project mailing + lists `. + +.. note:: + + Using a library that no longer builds against the latest Yocto + Project release and prints introspection related errors is a good + candidate for the previous procedure. + +Disabling the Generation of Introspection Data +============================================== + +You might find that you do not want to generate introspection data. Or, +perhaps QEMU does not work on your build host and target architecture +combination. If so, you can use either of the following methods to +disable GIR file generations: + +- Add the following to your distro configuration:: + + DISTRO_FEATURES_BACKFILL_CONSIDERED = "gobject-introspection-data" + + Adding this statement disables generating introspection data using + QEMU but will still enable building introspection tools and libraries + (i.e. building them does not require the use of QEMU). + +- Add the following to your machine configuration:: + + MACHINE_FEATURES_BACKFILL_CONSIDERED = "qemu-usermode" + + Adding this statement disables the use of QEMU when building packages for your + machine. Currently, this feature is used only by introspection + recipes and has the same effect as the previously described option. + + .. note:: + + Future releases of the Yocto Project might have other features + affected by this option. + +If you disable introspection data, you can still obtain it through other +means such as copying the data from a suitable sysroot, or by generating +it on the target hardware. The OpenEmbedded build system does not +currently provide specific support for these techniques. + +Testing that Introspection Works in an Image +============================================ + +Use the following procedure to test if generating introspection data is +working in an image: + +#. Make sure that "gobject-introspection-data" is not in + :term:`DISTRO_FEATURES_BACKFILL_CONSIDERED` + and that "qemu-usermode" is not in + :term:`MACHINE_FEATURES_BACKFILL_CONSIDERED`. + +#. Build ``core-image-sato``. + +#. Launch a Terminal and then start Python in the terminal. + +#. Enter the following in the terminal:: + + >>> from gi.repository import GLib + >>> GLib.get_host_name() + +#. For something a little more advanced, enter the following see: + https://python-gtk-3-tutorial.readthedocs.io/en/latest/introduction.html + +Known Issues +============ + +Here are know issues in GObject Introspection Support: + +- ``qemu-ppc64`` immediately crashes. Consequently, you cannot build + introspection data on that architecture. + +- x32 is not supported by QEMU. Consequently, introspection data is + disabled. + +- musl causes transient GLib binaries to crash on assertion failures. + Consequently, generating introspection data is disabled. + +- Because QEMU is not able to run the binaries correctly, introspection + is disabled for some specific packages under specific architectures + (e.g. ``gcr``, ``libsecret``, and ``webkit``). + +- QEMU usermode might not work properly when running 64-bit binaries + under 32-bit host machines. In particular, "qemumips64" is known to + not work under i686. + diff --git a/documentation/dev-manual/index.rst b/documentation/dev-manual/index.rst index f16b135c4d..3106b90a45 100644 --- a/documentation/dev-manual/index.rst +++ b/documentation/dev-manual/index.rst @@ -4,15 +4,48 @@ Yocto Project Development Tasks Manual ====================================== -| - .. toctree:: :caption: Table of Contents :numbered: intro start - common-tasks + layers + customizing-images + new-recipe + new-machine + upgrading-recipes + temporary-source-code + quilt.rst + development-shell + python-development-shell + building + speeding-up-build + libraries + prebuilt-libraries + x32-psabi + gobject-introspection + external-toolchain + wic + bmaptool + securing-images + custom-distribution + custom-template-configuration-directory + disk-space + packages + efficiently-fetching-sources + init-manager + device-manager + external-scm + read-only-rootfs + build-quality + runtime-testing + debugging + licenses + vulnerabilities + sbom + error-reporting-tool + wayland qemu .. include:: /boilerplate.rst diff --git a/documentation/dev-manual/init-manager.rst b/documentation/dev-manual/init-manager.rst new file mode 100644 index 0000000000..20d61ea830 --- /dev/null +++ b/documentation/dev-manual/init-manager.rst @@ -0,0 +1,162 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +.. _init-manager: + +Selecting an Initialization Manager +*********************************** + +By default, the Yocto Project uses :wikipedia:`SysVinit ` as +the initialization manager. There is also support for BusyBox init, a simpler +implementation, as well as support for :wikipedia:`systemd `, which +is a full replacement for init with parallel starting of services, reduced +shell overhead, increased security and resource limits for services, and other +features that are used by many distributions. + +Within the system, SysVinit and BusyBox init treat system components as +services. These services are maintained as shell scripts stored in the +``/etc/init.d/`` directory. + +SysVinit is more elaborate than BusyBox init and organizes services in +different run levels. This organization is maintained by putting links +to the services in the ``/etc/rcN.d/`` directories, where `N/` is one +of the following options: "S", "0", "1", "2", "3", "4", "5", or "6". + +.. note:: + + Each runlevel has a dependency on the previous runlevel. This + dependency allows the services to work properly. + +Both SysVinit and BusyBox init are configured through the ``/etc/inittab`` +file, with a very similar syntax, though of course BusyBox init features +are more limited. + +In comparison, systemd treats components as units. Using units is a +broader concept as compared to using a service. A unit includes several +different types of entities. ``Service`` is one of the types of entities. +The runlevel concept in SysVinit corresponds to the concept of a target +in systemd, where target is also a type of supported unit. + +In systems with SysVinit or BusyBox init, services load sequentially (i.e. one +by one) during init and parallelization is not supported. With systemd, services +start in parallel. This method can have an impact on the startup performance +of a given service, though systemd will also provide more services by default, +therefore increasing the total system boot time. systemd also substantially +increases system size because of its multiple components and the extra +dependencies it pulls. + +On the contrary, BusyBox init is the simplest and the lightest solution and +also comes with BusyBox mdev as device manager, a lighter replacement to +:wikipedia:`udev `, which SysVinit and systemd both use. + +The ":ref:`device-manager`" chapter has more details about device managers. + +Using SysVinit with udev +========================= + +SysVinit with the udev device manager corresponds to the +default setting in Poky. This corresponds to setting:: + + INIT_MANAGER = "sysvinit" + +Using BusyBox init with BusyBox mdev +==================================== + +BusyBox init with BusyBox mdev is the simplest and lightest solution +for small root filesystems. All you need is BusyBox, which most systems +have anyway:: + + INIT_MANAGER = "mdev-busybox" + +Using systemd +============= + +The last option is to use systemd together with the udev device +manager. This is the most powerful and versatile solution, especially +for more complex systems:: + + INIT_MANAGER = "systemd" + +This will enable systemd and remove sysvinit components from the image. +See :yocto_git:`meta/conf/distro/include/init-manager-systemd.inc +` for exact +details on what this does. + +Controling systemd from the target command line +----------------------------------------------- + +Here is a quick reference for controling systemd from the command line on the +target. Instead of opening and sometimes modifying files, most interaction +happens through the ``systemctl`` and ``journalctl`` commands: + +- ``systemctl status``: show the status of all services +- ``systemctl status ``: show the status of one service +- ``systemctl [start|stop] ``: start or stop a service +- ``systemctl [enable|disable] ``: enable or disable a service at boot time +- ``systemctl list-units``: list all available units +- ``journalctl -a``: show all logs for all services +- ``journalctl -f``: show only the last log entries, and keep printing updates as they arrive +- ``journalctl -u``: show only logs from a particular service + +Using systemd-journald without a traditional syslog daemon +---------------------------------------------------------- + +Counter-intuitively, ``systemd-journald`` is not a syslog runtime or provider, +and the proper way to use ``systemd-journald`` as your sole logging mechanism is to +effectively disable syslog entirely by setting these variables in your distribution +configuration file:: + + VIRTUAL-RUNTIME_syslog = "" + VIRTUAL-RUNTIME_base-utils-syslog = "" + +Doing so will prevent ``rsyslog`` / ``busybox-syslog`` from being pulled in by +default, leaving only ``systemd-journald``. + +Summary +------- + +The Yocto Project supports three different initialization managers, offering +increasing levels of complexity and functionality: + +.. list-table:: + :widths: 40 20 20 20 + :header-rows: 1 + + * - + - BusyBox init + - SysVinit + - systemd + * - Size + - Small + - Small + - Big [#footnote-systemd-size]_ + * - Complexity + - Small + - Medium + - High + * - Support for boot profiles + - No + - Yes ("runlevels") + - Yes ("targets") + * - Services defined as + - Shell scripts + - Shell scripts + - Description files + * - Starting services in parallel + - No + - No + - Yes + * - Setting service resource limits + - No + - No + - Yes + * - Support service isolation + - No + - No + - Yes + * - Integrated logging + - No + - No + - Yes + +.. [#footnote-systemd-size] Using systemd increases the ``core-image-minimal`` + image size by 160\% for ``qemux86-64`` on Mickledore (4.2), compared to SysVinit. diff --git a/documentation/dev-manual/layers.rst b/documentation/dev-manual/layers.rst new file mode 100644 index 0000000000..c5c34134b6 --- /dev/null +++ b/documentation/dev-manual/layers.rst @@ -0,0 +1,839 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Understanding and Creating Layers +********************************* + +The OpenEmbedded build system supports organizing +:term:`Metadata` into multiple layers. +Layers allow you to isolate different types of customizations from each +other. For introductory information on the Yocto Project Layer Model, +see the +":ref:`overview-manual/yp-intro:the yocto project layer model`" +section in the Yocto Project Overview and Concepts Manual. + +Creating Your Own Layer +======================= + +.. note:: + + It is very easy to create your own layers to use with the OpenEmbedded + build system, as the Yocto Project ships with tools that speed up creating + layers. This section describes the steps you perform by hand to create + layers so that you can better understand them. For information about the + layer-creation tools, see the + ":ref:`bsp-guide/bsp:creating a new bsp layer using the \`\`bitbake-layers\`\` script`" + section in the Yocto Project Board Support Package (BSP) Developer's + Guide and the ":ref:`dev-manual/layers:creating a general layer using the \`\`bitbake-layers\`\` script`" + section further down in this manual. + +Follow these general steps to create your layer without using tools: + +#. *Check Existing Layers:* Before creating a new layer, you should be + sure someone has not already created a layer containing the Metadata + you need. You can see the :oe_layerindex:`OpenEmbedded Metadata Index <>` + for a list of layers from the OpenEmbedded community that can be used in + the Yocto Project. You could find a layer that is identical or close + to what you need. + +#. *Create a Directory:* Create the directory for your layer. When you + create the layer, be sure to create the directory in an area not + associated with the Yocto Project :term:`Source Directory` + (e.g. the cloned ``poky`` repository). + + While not strictly required, prepend the name of the directory with + the string "meta-". For example:: + + meta-mylayer + meta-GUI_xyz + meta-mymachine + + With rare exceptions, a layer's name follows this form:: + + meta-root_name + + Following this layer naming convention can save + you trouble later when tools, components, or variables "assume" your + layer name begins with "meta-". A notable example is in configuration + files as shown in the following step where layer names without the + "meta-" string are appended to several variables used in the + configuration. + +#. *Create a Layer Configuration File:* Inside your new layer folder, + you need to create a ``conf/layer.conf`` file. It is easiest to take + an existing layer configuration file and copy that to your layer's + ``conf`` directory and then modify the file as needed. + + The ``meta-yocto-bsp/conf/layer.conf`` file in the Yocto Project + :yocto_git:`Source Repositories ` + demonstrates the required syntax. For your layer, you need to replace + "yoctobsp" with a unique identifier for your layer (e.g. "machinexyz" + for a layer named "meta-machinexyz"):: + + # We have a conf and classes directory, add to BBPATH + BBPATH .= ":${LAYERDIR}" + + # We have recipes-* directories, add to BBFILES + BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \ + ${LAYERDIR}/recipes-*/*/*.bbappend" + + BBFILE_COLLECTIONS += "yoctobsp" + BBFILE_PATTERN_yoctobsp = "^${LAYERDIR}/" + BBFILE_PRIORITY_yoctobsp = "5" + LAYERVERSION_yoctobsp = "4" + LAYERSERIES_COMPAT_yoctobsp = "dunfell" + + Following is an explanation of the layer configuration file: + + - :term:`BBPATH`: Adds the layer's + root directory to BitBake's search path. Through the use of the + :term:`BBPATH` variable, BitBake locates class files (``.bbclass``), + configuration files, and files that are included with ``include`` + and ``require`` statements. For these cases, BitBake uses the + first file that matches the name found in :term:`BBPATH`. This is + similar to the way the ``PATH`` variable is used for binaries. It + is recommended, therefore, that you use unique class and + configuration filenames in your custom layer. + + - :term:`BBFILES`: Defines the + location for all recipes in the layer. + + - :term:`BBFILE_COLLECTIONS`: + Establishes the current layer through a unique identifier that is + used throughout the OpenEmbedded build system to refer to the + layer. In this example, the identifier "yoctobsp" is the + representation for the container layer named "meta-yocto-bsp". + + - :term:`BBFILE_PATTERN`: + Expands immediately during parsing to provide the directory of the + layer. + + - :term:`BBFILE_PRIORITY`: + Establishes a priority to use for recipes in the layer when the + OpenEmbedded build finds recipes of the same name in different + layers. + + - :term:`LAYERVERSION`: + Establishes a version number for the layer. You can use this + version number to specify this exact version of the layer as a + dependency when using the + :term:`LAYERDEPENDS` + variable. + + - :term:`LAYERDEPENDS`: + Lists all layers on which this layer depends (if any). + + - :term:`LAYERSERIES_COMPAT`: + Lists the :yocto_wiki:`Yocto Project ` + releases for which the current version is compatible. This + variable is a good way to indicate if your particular layer is + current. + +#. *Add Content:* Depending on the type of layer, add the content. If + the layer adds support for a machine, add the machine configuration + in a ``conf/machine/`` file within the layer. If the layer adds + distro policy, add the distro configuration in a ``conf/distro/`` + file within the layer. If the layer introduces new recipes, put the + recipes you need in ``recipes-*`` subdirectories within the layer. + + .. note:: + + For an explanation of layer hierarchy that is compliant with the + Yocto Project, see the ":ref:`bsp-guide/bsp:example filesystem layout`" + section in the Yocto Project Board Support Package (BSP) Developer's Guide. + +#. *Optionally Test for Compatibility:* If you want permission to use + the Yocto Project Compatibility logo with your layer or application + that uses your layer, perform the steps to apply for compatibility. + See the + ":ref:`dev-manual/layers:making sure your layer is compatible with yocto project`" + section for more information. + +Following Best Practices When Creating Layers +============================================= + +To create layers that are easier to maintain and that will not impact +builds for other machines, you should consider the information in the +following list: + +- *Avoid "Overlaying" Entire Recipes from Other Layers in Your + Configuration:* In other words, do not copy an entire recipe into + your layer and then modify it. Rather, use an append file + (``.bbappend``) to override only those parts of the original recipe + you need to modify. + +- *Avoid Duplicating Include Files:* Use append files (``.bbappend``) + for each recipe that uses an include file. Or, if you are introducing + a new recipe that requires the included file, use the path relative + to the original layer directory to refer to the file. For example, + use ``require recipes-core/``\ `package`\ ``/``\ `file`\ ``.inc`` instead + of ``require`` `file`\ ``.inc``. If you're finding you have to overlay + the include file, it could indicate a deficiency in the include file + in the layer to which it originally belongs. If this is the case, you + should try to address that deficiency instead of overlaying the + include file. For example, you could address this by getting the + maintainer of the include file to add a variable or variables to make + it easy to override the parts needing to be overridden. + +- *Structure Your Layers:* Proper use of overrides within append files + and placement of machine-specific files within your layer can ensure + that a build is not using the wrong Metadata and negatively impacting + a build for a different machine. Following are some examples: + + - *Modify Variables to Support a Different Machine:* Suppose you + have a layer named ``meta-one`` that adds support for building + machine "one". To do so, you use an append file named + ``base-files.bbappend`` and create a dependency on "foo" by + altering the :term:`DEPENDS` + variable:: + + DEPENDS = "foo" + + The dependency is created during any + build that includes the layer ``meta-one``. However, you might not + want this dependency for all machines. For example, suppose you + are building for machine "two" but your ``bblayers.conf`` file has + the ``meta-one`` layer included. During the build, the + ``base-files`` for machine "two" will also have the dependency on + ``foo``. + + To make sure your changes apply only when building machine "one", + use a machine override with the :term:`DEPENDS` statement:: + + DEPENDS:one = "foo" + + You should follow the same strategy when using ``:append`` + and ``:prepend`` operations:: + + DEPENDS:append:one = " foo" + DEPENDS:prepend:one = "foo " + + As an actual example, here's a + snippet from the generic kernel include file ``linux-yocto.inc``, + wherein the kernel compile and link options are adjusted in the + case of a subset of the supported architectures:: + + DEPENDS:append:aarch64 = " libgcc" + KERNEL_CC:append:aarch64 = " ${TOOLCHAIN_OPTIONS}" + KERNEL_LD:append:aarch64 = " ${TOOLCHAIN_OPTIONS}" + + DEPENDS:append:nios2 = " libgcc" + KERNEL_CC:append:nios2 = " ${TOOLCHAIN_OPTIONS}" + KERNEL_LD:append:nios2 = " ${TOOLCHAIN_OPTIONS}" + + DEPENDS:append:arc = " libgcc" + KERNEL_CC:append:arc = " ${TOOLCHAIN_OPTIONS}" + KERNEL_LD:append:arc = " ${TOOLCHAIN_OPTIONS}" + + KERNEL_FEATURES:append:qemuall=" features/debug/printk.scc" + + - *Place Machine-Specific Files in Machine-Specific Locations:* When + you have a base recipe, such as ``base-files.bb``, that contains a + :term:`SRC_URI` statement to a + file, you can use an append file to cause the build to use your + own version of the file. For example, an append file in your layer + at ``meta-one/recipes-core/base-files/base-files.bbappend`` could + extend :term:`FILESPATH` using :term:`FILESEXTRAPATHS` as follows:: + + FILESEXTRAPATHS:prepend := "${THISDIR}/${BPN}:" + + The build for machine "one" will pick up your machine-specific file as + long as you have the file in + ``meta-one/recipes-core/base-files/base-files/``. However, if you + are building for a different machine and the ``bblayers.conf`` + file includes the ``meta-one`` layer and the location of your + machine-specific file is the first location where that file is + found according to :term:`FILESPATH`, builds for all machines will + also use that machine-specific file. + + You can make sure that a machine-specific file is used for a + particular machine by putting the file in a subdirectory specific + to the machine. For example, rather than placing the file in + ``meta-one/recipes-core/base-files/base-files/`` as shown above, + put it in ``meta-one/recipes-core/base-files/base-files/one/``. + Not only does this make sure the file is used only when building + for machine "one", but the build process locates the file more + quickly. + + In summary, you need to place all files referenced from + :term:`SRC_URI` in a machine-specific subdirectory within the layer in + order to restrict those files to machine-specific builds. + +- *Perform Steps to Apply for Yocto Project Compatibility:* If you want + permission to use the Yocto Project Compatibility logo with your + layer or application that uses your layer, perform the steps to apply + for compatibility. See the + ":ref:`dev-manual/layers:making sure your layer is compatible with yocto project`" + section for more information. + +- *Follow the Layer Naming Convention:* Store custom layers in a Git + repository that use the ``meta-layer_name`` format. + +- *Group Your Layers Locally:* Clone your repository alongside other + cloned ``meta`` directories from the :term:`Source Directory`. + +Making Sure Your Layer is Compatible With Yocto Project +======================================================= + +When you create a layer used with the Yocto Project, it is advantageous +to make sure that the layer interacts well with existing Yocto Project +layers (i.e. the layer is compatible with the Yocto Project). Ensuring +compatibility makes the layer easy to be consumed by others in the Yocto +Project community and could allow you permission to use the Yocto +Project Compatible Logo. + +.. note:: + + Only Yocto Project member organizations are permitted to use the + Yocto Project Compatible Logo. The logo is not available for general + use. For information on how to become a Yocto Project member + organization, see the :yocto_home:`Yocto Project Website <>`. + +The Yocto Project Compatibility Program consists of a layer application +process that requests permission to use the Yocto Project Compatibility +Logo for your layer and application. The process consists of two parts: + +#. Successfully passing a script (``yocto-check-layer``) that when run + against your layer, tests it against constraints based on experiences + of how layers have worked in the real world and where pitfalls have + been found. Getting a "PASS" result from the script is required for + successful compatibility registration. + +#. Completion of an application acceptance form, which you can find at + :yocto_home:`/webform/yocto-project-compatible-registration`. + +To be granted permission to use the logo, you need to satisfy the +following: + +- Be able to check the box indicating that you got a "PASS" when + running the script against your layer. + +- Answer "Yes" to the questions on the form or have an acceptable + explanation for any questions answered "No". + +- Be a Yocto Project Member Organization. + +The remainder of this section presents information on the registration +form and on the ``yocto-check-layer`` script. + +Yocto Project Compatible Program Application +-------------------------------------------- + +Use the form to apply for your layer's approval. Upon successful +application, you can use the Yocto Project Compatibility Logo with your +layer and the application that uses your layer. + +To access the form, use this link: +:yocto_home:`/webform/yocto-project-compatible-registration`. +Follow the instructions on the form to complete your application. + +The application consists of the following sections: + +- *Contact Information:* Provide your contact information as the fields + require. Along with your information, provide the released versions + of the Yocto Project for which your layer is compatible. + +- *Acceptance Criteria:* Provide "Yes" or "No" answers for each of the + items in the checklist. There is space at the bottom of the form for + any explanations for items for which you answered "No". + +- *Recommendations:* Provide answers for the questions regarding Linux + kernel use and build success. + +``yocto-check-layer`` Script +---------------------------- + +The ``yocto-check-layer`` script provides you a way to assess how +compatible your layer is with the Yocto Project. You should run this +script prior to using the form to apply for compatibility as described +in the previous section. You need to achieve a "PASS" result in order to +have your application form successfully processed. + +The script divides tests into three areas: COMMON, BSP, and DISTRO. For +example, given a distribution layer (DISTRO), the layer must pass both +the COMMON and DISTRO related tests. Furthermore, if your layer is a BSP +layer, the layer must pass the COMMON and BSP set of tests. + +To execute the script, enter the following commands from your build +directory:: + + $ source oe-init-build-env + $ yocto-check-layer your_layer_directory + +Be sure to provide the actual directory for your +layer as part of the command. + +Entering the command causes the script to determine the type of layer +and then to execute a set of specific tests against the layer. The +following list overviews the test: + +- ``common.test_readme``: Tests if a ``README`` file exists in the + layer and the file is not empty. + +- ``common.test_parse``: Tests to make sure that BitBake can parse the + files without error (i.e. ``bitbake -p``). + +- ``common.test_show_environment``: Tests that the global or per-recipe + environment is in order without errors (i.e. ``bitbake -e``). + +- ``common.test_world``: Verifies that ``bitbake world`` works. + +- ``common.test_signatures``: Tests to be sure that BSP and DISTRO + layers do not come with recipes that change signatures. + +- ``common.test_layerseries_compat``: Verifies layer compatibility is + set properly. + +- ``bsp.test_bsp_defines_machines``: Tests if a BSP layer has machine + configurations. + +- ``bsp.test_bsp_no_set_machine``: Tests to ensure a BSP layer does not + set the machine when the layer is added. + +- ``bsp.test_machine_world``: Verifies that ``bitbake world`` works + regardless of which machine is selected. + +- ``bsp.test_machine_signatures``: Verifies that building for a + particular machine affects only the signature of tasks specific to + that machine. + +- ``distro.test_distro_defines_distros``: Tests if a DISTRO layer has + distro configurations. + +- ``distro.test_distro_no_set_distros``: Tests to ensure a DISTRO layer + does not set the distribution when the layer is added. + +Enabling Your Layer +=================== + +Before the OpenEmbedded build system can use your new layer, you need to +enable it. To enable your layer, simply add your layer's path to the +:term:`BBLAYERS` variable in your ``conf/bblayers.conf`` file, which is +found in the :term:`Build Directory`. The following example shows how to +enable your new ``meta-mylayer`` layer (note how your new layer exists +outside of the official ``poky`` repository which you would have checked +out earlier):: + + # POKY_BBLAYERS_CONF_VERSION is increased each time build/conf/bblayers.conf + # changes incompatibly + POKY_BBLAYERS_CONF_VERSION = "2" + BBPATH = "${TOPDIR}" + BBFILES ?= "" + BBLAYERS ?= " \ + /home/user/poky/meta \ + /home/user/poky/meta-poky \ + /home/user/poky/meta-yocto-bsp \ + /home/user/mystuff/meta-mylayer \ + " + +BitBake parses each ``conf/layer.conf`` file from the top down as +specified in the :term:`BBLAYERS` variable within the ``conf/bblayers.conf`` +file. During the processing of each ``conf/layer.conf`` file, BitBake +adds the recipes, classes and configurations contained within the +particular layer to the source directory. + +Appending Other Layers Metadata With Your Layer +=============================================== + +A recipe that appends Metadata to another recipe is called a BitBake +append file. A BitBake append file uses the ``.bbappend`` file type +suffix, while the corresponding recipe to which Metadata is being +appended uses the ``.bb`` file type suffix. + +You can use a ``.bbappend`` file in your layer to make additions or +changes to the content of another layer's recipe without having to copy +the other layer's recipe into your layer. Your ``.bbappend`` file +resides in your layer, while the main ``.bb`` recipe file to which you +are appending Metadata resides in a different layer. + +Being able to append information to an existing recipe not only avoids +duplication, but also automatically applies recipe changes from a +different layer into your layer. If you were copying recipes, you would +have to manually merge changes as they occur. + +When you create an append file, you must use the same root name as the +corresponding recipe file. For example, the append file +``someapp_3.1.bbappend`` must apply to ``someapp_3.1.bb``. This +means the original recipe and append filenames are version +number-specific. If the corresponding recipe is renamed to update to a +newer version, you must also rename and possibly update the +corresponding ``.bbappend`` as well. During the build process, BitBake +displays an error on starting if it detects a ``.bbappend`` file that +does not have a corresponding recipe with a matching name. See the +:term:`BB_DANGLINGAPPENDS_WARNONLY` +variable for information on how to handle this error. + +Overlaying a File Using Your Layer +---------------------------------- + +As an example, consider the main formfactor recipe and a corresponding +formfactor append file both from the :term:`Source Directory`. +Here is the main +formfactor recipe, which is named ``formfactor_0.0.bb`` and located in +the "meta" layer at ``meta/recipes-bsp/formfactor``:: + + SUMMARY = "Device formfactor information" + DESCRIPTION = "A formfactor configuration file provides information about the \ + target hardware for which the image is being built and information that the \ + build system cannot obtain from other sources such as the kernel." + SECTION = "base" + LICENSE = "MIT" + LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420" + PR = "r45" + + SRC_URI = "file://config file://machconfig" + S = "${WORKDIR}" + + PACKAGE_ARCH = "${MACHINE_ARCH}" + INHIBIT_DEFAULT_DEPS = "1" + + do_install() { + # Install file only if it has contents + install -d ${D}${sysconfdir}/formfactor/ + install -m 0644 ${S}/config ${D}${sysconfdir}/formfactor/ + if [ -s "${S}/machconfig" ]; then + install -m 0644 ${S}/machconfig ${D}${sysconfdir}/formfactor/ + fi + } + +In the main recipe, note the :term:`SRC_URI` +variable, which tells the OpenEmbedded build system where to find files +during the build. + +Following is the append file, which is named ``formfactor_0.0.bbappend`` +and is from the Raspberry Pi BSP Layer named ``meta-raspberrypi``. The +file is in the layer at ``recipes-bsp/formfactor``:: + + FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:" + +By default, the build system uses the +:term:`FILESPATH` variable to +locate files. This append file extends the locations by setting the +:term:`FILESEXTRAPATHS` +variable. Setting this variable in the ``.bbappend`` file is the most +reliable and recommended method for adding directories to the search +path used by the build system to find files. + +The statement in this example extends the directories to include +``${``\ :term:`THISDIR`\ ``}/${``\ :term:`PN`\ ``}``, +which resolves to a directory named ``formfactor`` in the same directory +in which the append file resides (i.e. +``meta-raspberrypi/recipes-bsp/formfactor``. This implies that you must +have the supporting directory structure set up that will contain any +files or patches you will be including from the layer. + +Using the immediate expansion assignment operator ``:=`` is important +because of the reference to :term:`THISDIR`. The trailing colon character is +important as it ensures that items in the list remain colon-separated. + +.. note:: + + BitBake automatically defines the :term:`THISDIR` variable. You should + never set this variable yourself. Using ":prepend" as part of the + :term:`FILESEXTRAPATHS` ensures your path will be searched prior to other + paths in the final list. + + Also, not all append files add extra files. Many append files simply + allow to add build options (e.g. ``systemd``). For these cases, your + append file would not even use the :term:`FILESEXTRAPATHS` statement. + +The end result of this ``.bbappend`` file is that on a Raspberry Pi, where +``rpi`` will exist in the list of :term:`OVERRIDES`, the file +``meta-raspberrypi/recipes-bsp/formfactor/formfactor/rpi/machconfig`` will be +used during :ref:`ref-tasks-fetch` and the test for a non-zero file size in +:ref:`ref-tasks-install` will return true, and the file will be installed. + +Installing Additional Files Using Your Layer +-------------------------------------------- + +As another example, consider the main ``xserver-xf86-config`` recipe and a +corresponding ``xserver-xf86-config`` append file both from the :term:`Source +Directory`. Here is the main ``xserver-xf86-config`` recipe, which is named +``xserver-xf86-config_0.1.bb`` and located in the "meta" layer at +``meta/recipes-graphics/xorg-xserver``:: + + SUMMARY = "X.Org X server configuration file" + HOMEPAGE = "http://www.x.org" + SECTION = "x11/base" + LICENSE = "MIT" + LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420" + PR = "r33" + + SRC_URI = "file://xorg.conf" + + S = "${WORKDIR}" + + CONFFILES:${PN} = "${sysconfdir}/X11/xorg.conf" + + PACKAGE_ARCH = "${MACHINE_ARCH}" + ALLOW_EMPTY:${PN} = "1" + + do_install () { + if test -s ${WORKDIR}/xorg.conf; then + install -d ${D}/${sysconfdir}/X11 + install -m 0644 ${WORKDIR}/xorg.conf ${D}/${sysconfdir}/X11/ + fi + } + +Following is the append file, which is named ``xserver-xf86-config_%.bbappend`` +and is from the Raspberry Pi BSP Layer named ``meta-raspberrypi``. The +file is in the layer at ``recipes-graphics/xorg-xserver``:: + + FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}:" + + SRC_URI:append:rpi = " \ + file://xorg.conf.d/98-pitft.conf \ + file://xorg.conf.d/99-calibration.conf \ + " + do_install:append:rpi () { + PITFT="${@bb.utils.contains("MACHINE_FEATURES", "pitft", "1", "0", d)}" + if [ "${PITFT}" = "1" ]; then + install -d ${D}/${sysconfdir}/X11/xorg.conf.d/ + install -m 0644 ${WORKDIR}/xorg.conf.d/98-pitft.conf ${D}/${sysconfdir}/X11/xorg.conf.d/ + install -m 0644 ${WORKDIR}/xorg.conf.d/99-calibration.conf ${D}/${sysconfdir}/X11/xorg.conf.d/ + fi + } + + FILES:${PN}:append:rpi = " ${sysconfdir}/X11/xorg.conf.d/*" + +Building off of the previous example, we once again are setting the +:term:`FILESEXTRAPATHS` variable. In this case we are also using +:term:`SRC_URI` to list additional source files to use when ``rpi`` is found in +the list of :term:`OVERRIDES`. The :ref:`ref-tasks-install` task will then perform a +check for an additional :term:`MACHINE_FEATURES` that if set will cause these +additional files to be installed. These additional files are listed in +:term:`FILES` so that they will be packaged. + +Prioritizing Your Layer +======================= + +Each layer is assigned a priority value. Priority values control which +layer takes precedence if there are recipe files with the same name in +multiple layers. For these cases, the recipe file from the layer with a +higher priority number takes precedence. Priority values also affect the +order in which multiple ``.bbappend`` files for the same recipe are +applied. You can either specify the priority manually, or allow the +build system to calculate it based on the layer's dependencies. + +To specify the layer's priority manually, use the +:term:`BBFILE_PRIORITY` +variable and append the layer's root name:: + + BBFILE_PRIORITY_mylayer = "1" + +.. note:: + + It is possible for a recipe with a lower version number + :term:`PV` in a layer that has a higher + priority to take precedence. + + Also, the layer priority does not currently affect the precedence + order of ``.conf`` or ``.bbclass`` files. Future versions of BitBake + might address this. + +Managing Layers +=============== + +You can use the BitBake layer management tool ``bitbake-layers`` to +provide a view into the structure of recipes across a multi-layer +project. Being able to generate output that reports on configured layers +with their paths and priorities and on ``.bbappend`` files and their +applicable recipes can help to reveal potential problems. + +For help on the BitBake layer management tool, use the following +command:: + + $ bitbake-layers --help + +The following list describes the available commands: + +- ``help:`` Displays general help or help on a specified command. + +- ``show-layers:`` Shows the current configured layers. + +- ``show-overlayed:`` Lists overlayed recipes. A recipe is overlayed + when a recipe with the same name exists in another layer that has a + higher layer priority. + +- ``show-recipes:`` Lists available recipes and the layers that + provide them. + +- ``show-appends:`` Lists ``.bbappend`` files and the recipe files to + which they apply. + +- ``show-cross-depends:`` Lists dependency relationships between + recipes that cross layer boundaries. + +- ``add-layer:`` Adds a layer to ``bblayers.conf``. + +- ``remove-layer:`` Removes a layer from ``bblayers.conf`` + +- ``flatten:`` Flattens the layer configuration into a separate + output directory. Flattening your layer configuration builds a + "flattened" directory that contains the contents of all layers, with + any overlayed recipes removed and any ``.bbappend`` files appended to + the corresponding recipes. You might have to perform some manual + cleanup of the flattened layer as follows: + + - Non-recipe files (such as patches) are overwritten. The flatten + command shows a warning for these files. + + - Anything beyond the normal layer setup has been added to the + ``layer.conf`` file. Only the lowest priority layer's + ``layer.conf`` is used. + + - Overridden and appended items from ``.bbappend`` files need to be + cleaned up. The contents of each ``.bbappend`` end up in the + flattened recipe. However, if there are appended or changed + variable values, you need to tidy these up yourself. Consider the + following example. Here, the ``bitbake-layers`` command adds the + line ``#### bbappended ...`` so that you know where the following + lines originate:: + + ... + DESCRIPTION = "A useful utility" + ... + EXTRA_OECONF = "--enable-something" + ... + + #### bbappended from meta-anotherlayer #### + + DESCRIPTION = "Customized utility" + EXTRA_OECONF += "--enable-somethingelse" + + + Ideally, you would tidy up these utilities as follows:: + + ... + DESCRIPTION = "Customized utility" + ... + EXTRA_OECONF = "--enable-something --enable-somethingelse" + ... + +- ``layerindex-fetch``: Fetches a layer from a layer index, along + with its dependent layers, and adds the layers to the + ``conf/bblayers.conf`` file. + +- ``layerindex-show-depends``: Finds layer dependencies from the + layer index. + +- ``create-layer``: Creates a basic layer. + +Creating a General Layer Using the ``bitbake-layers`` Script +============================================================ + +The ``bitbake-layers`` script with the ``create-layer`` subcommand +simplifies creating a new general layer. + +.. note:: + + - For information on BSP layers, see the ":ref:`bsp-guide/bsp:bsp layers`" + section in the Yocto + Project Board Specific (BSP) Developer's Guide. + + - In order to use a layer with the OpenEmbedded build system, you + need to add the layer to your ``bblayers.conf`` configuration + file. See the ":ref:`dev-manual/layers:adding a layer using the \`\`bitbake-layers\`\` script`" + section for more information. + +The default mode of the script's operation with this subcommand is to +create a layer with the following: + +- A layer priority of 6. + +- A ``conf`` subdirectory that contains a ``layer.conf`` file. + +- A ``recipes-example`` subdirectory that contains a further + subdirectory named ``example``, which contains an ``example.bb`` + recipe file. + +- A ``COPYING.MIT``, which is the license statement for the layer. The + script assumes you want to use the MIT license, which is typical for + most layers, for the contents of the layer itself. + +- A ``README`` file, which is a file describing the contents of your + new layer. + +In its simplest form, you can use the following command form to create a +layer. The command creates a layer whose name corresponds to +"your_layer_name" in the current directory:: + + $ bitbake-layers create-layer your_layer_name + +As an example, the following command creates a layer named ``meta-scottrif`` +in your home directory:: + + $ cd /usr/home + $ bitbake-layers create-layer meta-scottrif + NOTE: Starting bitbake server... + Add your new layer with 'bitbake-layers add-layer meta-scottrif' + +If you want to set the priority of the layer to other than the default +value of "6", you can either use the ``--priority`` option or you +can edit the +:term:`BBFILE_PRIORITY` value +in the ``conf/layer.conf`` after the script creates it. Furthermore, if +you want to give the example recipe file some name other than the +default, you can use the ``--example-recipe-name`` option. + +The easiest way to see how the ``bitbake-layers create-layer`` command +works is to experiment with the script. You can also read the usage +information by entering the following:: + + $ bitbake-layers create-layer --help + NOTE: Starting bitbake server... + usage: bitbake-layers create-layer [-h] [--priority PRIORITY] + [--example-recipe-name EXAMPLERECIPE] + layerdir + + Create a basic layer + + positional arguments: + layerdir Layer directory to create + + optional arguments: + -h, --help show this help message and exit + --priority PRIORITY, -p PRIORITY + Layer directory to create + --example-recipe-name EXAMPLERECIPE, -e EXAMPLERECIPE + Filename of the example recipe + +Adding a Layer Using the ``bitbake-layers`` Script +================================================== + +Once you create your general layer, you must add it to your +``bblayers.conf`` file. Adding the layer to this configuration file +makes the OpenEmbedded build system aware of your layer so that it can +search it for metadata. + +Add your layer by using the ``bitbake-layers add-layer`` command:: + + $ bitbake-layers add-layer your_layer_name + +Here is an example that adds a +layer named ``meta-scottrif`` to the configuration file. Following the +command that adds the layer is another ``bitbake-layers`` command that +shows the layers that are in your ``bblayers.conf`` file:: + + $ bitbake-layers add-layer meta-scottrif + NOTE: Starting bitbake server... + Parsing recipes: 100% |##########################################################| Time: 0:00:49 + Parsing of 1441 .bb files complete (0 cached, 1441 parsed). 2055 targets, 56 skipped, 0 masked, 0 errors. + $ bitbake-layers show-layers + NOTE: Starting bitbake server... + layer path priority + ========================================================================== + meta /home/scottrif/poky/meta 5 + meta-poky /home/scottrif/poky/meta-poky 5 + meta-yocto-bsp /home/scottrif/poky/meta-yocto-bsp 5 + workspace /home/scottrif/poky/build/workspace 99 + meta-scottrif /home/scottrif/poky/build/meta-scottrif 6 + + +Adding the layer to this file +enables the build system to locate the layer during the build. + +.. note:: + + During a build, the OpenEmbedded build system looks in the layers + from the top of the list down to the bottom in that order. + diff --git a/documentation/dev-manual/libraries.rst b/documentation/dev-manual/libraries.rst new file mode 100644 index 0000000000..ae4ca27209 --- /dev/null +++ b/documentation/dev-manual/libraries.rst @@ -0,0 +1,267 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Working With Libraries +********************** + +Libraries are an integral part of your system. This section describes +some common practices you might find helpful when working with libraries +to build your system: + +- :ref:`How to include static library files + ` + +- :ref:`How to use the Multilib feature to combine multiple versions of + library files into a single image + ` + +- :ref:`How to install multiple versions of the same library in parallel on + the same system + ` + +Including Static Library Files +============================== + +If you are building a library and the library offers static linking, you +can control which static library files (``*.a`` files) get included in +the built library. + +The :term:`PACKAGES` and +:term:`FILES:* ` variables in the +``meta/conf/bitbake.conf`` configuration file define how files installed +by the :ref:`ref-tasks-install` task are packaged. By default, the :term:`PACKAGES` +variable includes ``${PN}-staticdev``, which represents all static +library files. + +.. note:: + + Some previously released versions of the Yocto Project defined the + static library files through ``${PN}-dev``. + +Following is part of the BitBake configuration file, where you can see +how the static library files are defined:: + + PACKAGE_BEFORE_PN ?= "" + PACKAGES = "${PN}-src ${PN}-dbg ${PN}-staticdev ${PN}-dev ${PN}-doc ${PN}-locale ${PACKAGE_BEFORE_PN} ${PN}" + PACKAGES_DYNAMIC = "^${PN}-locale-.*" + FILES = "" + + FILES:${PN} = "${bindir}/* ${sbindir}/* ${libexecdir}/* ${libdir}/lib*${SOLIBS} \ + ${sysconfdir} ${sharedstatedir} ${localstatedir} \ + ${base_bindir}/* ${base_sbindir}/* \ + ${base_libdir}/*${SOLIBS} \ + ${base_prefix}/lib/udev ${prefix}/lib/udev \ + ${base_libdir}/udev ${libdir}/udev \ + ${datadir}/${BPN} ${libdir}/${BPN}/* \ + ${datadir}/pixmaps ${datadir}/applications \ + ${datadir}/idl ${datadir}/omf ${datadir}/sounds \ + ${libdir}/bonobo/servers" + + FILES:${PN}-bin = "${bindir}/* ${sbindir}/*" + + FILES:${PN}-doc = "${docdir} ${mandir} ${infodir} ${datadir}/gtk-doc \ + ${datadir}/gnome/help" + SECTION:${PN}-doc = "doc" + + FILES_SOLIBSDEV ?= "${base_libdir}/lib*${SOLIBSDEV} ${libdir}/lib*${SOLIBSDEV}" + FILES:${PN}-dev = "${includedir} ${FILES_SOLIBSDEV} ${libdir}/*.la \ + ${libdir}/*.o ${libdir}/pkgconfig ${datadir}/pkgconfig \ + ${datadir}/aclocal ${base_libdir}/*.o \ + ${libdir}/${BPN}/*.la ${base_libdir}/*.la \ + ${libdir}/cmake ${datadir}/cmake" + SECTION:${PN}-dev = "devel" + ALLOW_EMPTY:${PN}-dev = "1" + RDEPENDS:${PN}-dev = "${PN} (= ${EXTENDPKGV})" + + FILES:${PN}-staticdev = "${libdir}/*.a ${base_libdir}/*.a ${libdir}/${BPN}/*.a" + SECTION:${PN}-staticdev = "devel" + RDEPENDS:${PN}-staticdev = "${PN}-dev (= ${EXTENDPKGV})" + +Combining Multiple Versions of Library Files into One Image +=========================================================== + +The build system offers the ability to build libraries with different +target optimizations or architecture formats and combine these together +into one system image. You can link different binaries in the image +against the different libraries as needed for specific use cases. This +feature is called "Multilib". + +An example would be where you have most of a system compiled in 32-bit +mode using 32-bit libraries, but you have something large, like a +database engine, that needs to be a 64-bit application and uses 64-bit +libraries. Multilib allows you to get the best of both 32-bit and 64-bit +libraries. + +While the Multilib feature is most commonly used for 32 and 64-bit +differences, the approach the build system uses facilitates different +target optimizations. You could compile some binaries to use one set of +libraries and other binaries to use a different set of libraries. The +libraries could differ in architecture, compiler options, or other +optimizations. + +There are several examples in the ``meta-skeleton`` layer found in the +:term:`Source Directory`: + +- :oe_git:`conf/multilib-example.conf ` + configuration file. + +- :oe_git:`conf/multilib-example2.conf ` + configuration file. + +- :oe_git:`recipes-multilib/images/core-image-multilib-example.bb ` + recipe + +Preparing to Use Multilib +------------------------- + +User-specific requirements drive the Multilib feature. Consequently, +there is no one "out-of-the-box" configuration that would +meet your needs. + +In order to enable Multilib, you first need to ensure your recipe is +extended to support multiple libraries. Many standard recipes are +already extended and support multiple libraries. You can check in the +``meta/conf/multilib.conf`` configuration file in the +:term:`Source Directory` to see how this is +done using the +:term:`BBCLASSEXTEND` variable. +Eventually, all recipes will be covered and this list will not be +needed. + +For the most part, the :ref:`Multilib ` +class extension works automatically to +extend the package name from ``${PN}`` to ``${MLPREFIX}${PN}``, where +:term:`MLPREFIX` is the particular multilib (e.g. "lib32-" or "lib64-"). +Standard variables such as +:term:`DEPENDS`, +:term:`RDEPENDS`, +:term:`RPROVIDES`, +:term:`RRECOMMENDS`, +:term:`PACKAGES`, and +:term:`PACKAGES_DYNAMIC` are +automatically extended by the system. If you are extending any manual +code in the recipe, you can use the ``${MLPREFIX}`` variable to ensure +those names are extended correctly. + +Using Multilib +-------------- + +After you have set up the recipes, you need to define the actual +combination of multiple libraries you want to build. You accomplish this +through your ``local.conf`` configuration file in the +:term:`Build Directory`. An example configuration would be as follows:: + + MACHINE = "qemux86-64" + require conf/multilib.conf + MULTILIBS = "multilib:lib32" + DEFAULTTUNE:virtclass-multilib-lib32 = "x86" + IMAGE_INSTALL:append = " lib32-glib-2.0" + +This example enables an additional library named +``lib32`` alongside the normal target packages. When combining these +"lib32" alternatives, the example uses "x86" for tuning. For information +on this particular tuning, see +``meta/conf/machine/include/ia32/arch-ia32.inc``. + +The example then includes ``lib32-glib-2.0`` in all the images, which +illustrates one method of including a multiple library dependency. You +can use a normal image build to include this dependency, for example:: + + $ bitbake core-image-sato + +You can also build Multilib packages +specifically with a command like this:: + + $ bitbake lib32-glib-2.0 + +Additional Implementation Details +--------------------------------- + +There are generic implementation details as well as details that are specific to +package management systems. Following are implementation details +that exist regardless of the package management system: + +- The typical convention used for the class extension code as used by + Multilib assumes that all package names specified in + :term:`PACKAGES` that contain + ``${PN}`` have ``${PN}`` at the start of the name. When that + convention is not followed and ``${PN}`` appears at the middle or the + end of a name, problems occur. + +- The :term:`TARGET_VENDOR` + value under Multilib will be extended to "-vendormlmultilib" (e.g. + "-pokymllib32" for a "lib32" Multilib with Poky). The reason for this + slightly unwieldy contraction is that any "-" characters in the + vendor string presently break Autoconf's ``config.sub``, and other + separators are problematic for different reasons. + +Here are the implementation details for the RPM Package Management System: + +- A unique architecture is defined for the Multilib packages, along + with creating a unique deploy folder under ``tmp/deploy/rpm`` in the + :term:`Build Directory`. For example, consider ``lib32`` in a + ``qemux86-64`` image. The possible architectures in the system are "all", + "qemux86_64", "lib32:qemux86_64", and "lib32:x86". + +- The ``${MLPREFIX}`` variable is stripped from ``${PN}`` during RPM + packaging. The naming for a normal RPM package and a Multilib RPM + package in a ``qemux86-64`` system resolves to something similar to + ``bash-4.1-r2.x86_64.rpm`` and ``bash-4.1.r2.lib32_x86.rpm``, + respectively. + +- When installing a Multilib image, the RPM backend first installs the + base image and then installs the Multilib libraries. + +- The build system relies on RPM to resolve the identical files in the + two (or more) Multilib packages. + +Here are the implementation details for the IPK Package Management System: + +- The ``${MLPREFIX}`` is not stripped from ``${PN}`` during IPK + packaging. The naming for a normal RPM package and a Multilib IPK + package in a ``qemux86-64`` system resolves to something like + ``bash_4.1-r2.x86_64.ipk`` and ``lib32-bash_4.1-rw:x86.ipk``, + respectively. + +- The IPK deploy folder is not modified with ``${MLPREFIX}`` because + packages with and without the Multilib feature can exist in the same + folder due to the ``${PN}`` differences. + +- IPK defines a sanity check for Multilib installation using certain + rules for file comparison, overridden, etc. + +Installing Multiple Versions of the Same Library +================================================ + +There are be situations where you need to install and use multiple versions +of the same library on the same system at the same time. This +almost always happens when a library API changes and you have +multiple pieces of software that depend on the separate versions of the +library. To accommodate these situations, you can install multiple +versions of the same library in parallel on the same system. + +The process is straightforward as long as the libraries use proper +versioning. With properly versioned libraries, all you need to do to +individually specify the libraries is create separate, appropriately +named recipes where the :term:`PN` part of +the name includes a portion that differentiates each library version +(e.g. the major part of the version number). Thus, instead of having a +single recipe that loads one version of a library (e.g. ``clutter``), +you provide multiple recipes that result in different versions of the +libraries you want. As an example, the following two recipes would allow +the two separate versions of the ``clutter`` library to co-exist on the +same system: + +.. code-block:: none + + clutter-1.6_1.6.20.bb + clutter-1.8_1.8.4.bb + +Additionally, if +you have other recipes that depend on a given library, you need to use +the :term:`DEPENDS` variable to +create the dependency. Continuing with the same example, if you want to +have a recipe depend on the 1.8 version of the ``clutter`` library, use +the following in your recipe:: + + DEPENDS = "clutter-1.8" + diff --git a/documentation/dev-manual/licenses.rst b/documentation/dev-manual/licenses.rst new file mode 100644 index 0000000000..b485f77708 --- /dev/null +++ b/documentation/dev-manual/licenses.rst @@ -0,0 +1,524 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Working With Licenses +********************* + +As mentioned in the ":ref:`overview-manual/development-environment:licensing`" +section in the Yocto Project Overview and Concepts Manual, open source +projects are open to the public and they consequently have different +licensing structures in place. This section describes the mechanism by +which the :term:`OpenEmbedded Build System` +tracks changes to +licensing text and covers how to maintain open source license compliance +during your project's lifecycle. The section also describes how to +enable commercially licensed recipes, which by default are disabled. + +Tracking License Changes +======================== + +The license of an upstream project might change in the future. In order +to prevent these changes going unnoticed, the +:term:`LIC_FILES_CHKSUM` +variable tracks changes to the license text. The checksums are validated +at the end of the configure step, and if the checksums do not match, the +build will fail. + +Specifying the ``LIC_FILES_CHKSUM`` Variable +-------------------------------------------- + +The :term:`LIC_FILES_CHKSUM` variable contains checksums of the license text +in the source code for the recipe. Following is an example of how to +specify :term:`LIC_FILES_CHKSUM`:: + + LIC_FILES_CHKSUM = "file://COPYING;md5=xxxx \ + file://licfile1.txt;beginline=5;endline=29;md5=yyyy \ + file://licfile2.txt;endline=50;md5=zzzz \ + ..." + +.. note:: + + - When using "beginline" and "endline", realize that line numbering + begins with one and not zero. Also, the included lines are + inclusive (i.e. lines five through and including 29 in the + previous example for ``licfile1.txt``). + + - When a license check fails, the selected license text is included + as part of the QA message. Using this output, you can determine + the exact start and finish for the needed license text. + +The build system uses the :term:`S` +variable as the default directory when searching files listed in +:term:`LIC_FILES_CHKSUM`. The previous example employs the default +directory. + +Consider this next example:: + + LIC_FILES_CHKSUM = "file://src/ls.c;beginline=5;endline=16;\ + md5=bb14ed3c4cda583abc85401304b5cd4e" + LIC_FILES_CHKSUM = "file://${WORKDIR}/license.html;md5=5c94767cedb5d6987c902ac850ded2c6" + +The first line locates a file in ``${S}/src/ls.c`` and isolates lines +five through 16 as license text. The second line refers to a file in +:term:`WORKDIR`. + +Note that :term:`LIC_FILES_CHKSUM` variable is mandatory for all recipes, +unless the :term:`LICENSE` variable is set to "CLOSED". + +Explanation of Syntax +--------------------- + +As mentioned in the previous section, the :term:`LIC_FILES_CHKSUM` variable +lists all the important files that contain the license text for the +source code. It is possible to specify a checksum for an entire file, or +a specific section of a file (specified by beginning and ending line +numbers with the "beginline" and "endline" parameters, respectively). +The latter is useful for source files with a license notice header, +README documents, and so forth. If you do not use the "beginline" +parameter, then it is assumed that the text begins on the first line of +the file. Similarly, if you do not use the "endline" parameter, it is +assumed that the license text ends with the last line of the file. + +The "md5" parameter stores the md5 checksum of the license text. If the +license text changes in any way as compared to this parameter then a +mismatch occurs. This mismatch triggers a build failure and notifies the +developer. Notification allows the developer to review and address the +license text changes. Also note that if a mismatch occurs during the +build, the correct md5 checksum is placed in the build log and can be +easily copied to the recipe. + +There is no limit to how many files you can specify using the +:term:`LIC_FILES_CHKSUM` variable. Generally, however, every project +requires a few specifications for license tracking. Many projects have a +"COPYING" file that stores the license information for all the source +code files. This practice allows you to just track the "COPYING" file as +long as it is kept up to date. + +.. note:: + + - If you specify an empty or invalid "md5" parameter, + :term:`BitBake` returns an md5 + mis-match error and displays the correct "md5" parameter value + during the build. The correct parameter is also captured in the + build log. + + - If the whole file contains only license text, you do not need to + use the "beginline" and "endline" parameters. + +Enabling Commercially Licensed Recipes +====================================== + +By default, the OpenEmbedded build system disables components that have +commercial or other special licensing requirements. Such requirements +are defined on a recipe-by-recipe basis through the +:term:`LICENSE_FLAGS` variable +definition in the affected recipe. For instance, the +``poky/meta/recipes-multimedia/gstreamer/gst-plugins-ugly`` recipe +contains the following statement:: + + LICENSE_FLAGS = "commercial" + +Here is a +slightly more complicated example that contains both an explicit recipe +name and version (after variable expansion):: + + LICENSE_FLAGS = "license_${PN}_${PV}" + +In order for a component restricted by a +:term:`LICENSE_FLAGS` definition to be enabled and included in an image, it +needs to have a matching entry in the global +:term:`LICENSE_FLAGS_ACCEPTED` +variable, which is a variable typically defined in your ``local.conf`` +file. For example, to enable the +``poky/meta/recipes-multimedia/gstreamer/gst-plugins-ugly`` package, you +could add either the string "commercial_gst-plugins-ugly" or the more +general string "commercial" to :term:`LICENSE_FLAGS_ACCEPTED`. See the +":ref:`dev-manual/licenses:license flag matching`" section for a full +explanation of how :term:`LICENSE_FLAGS` matching works. Here is the +example:: + + LICENSE_FLAGS_ACCEPTED = "commercial_gst-plugins-ugly" + +Likewise, to additionally enable the package built from the recipe +containing ``LICENSE_FLAGS = "license_${PN}_${PV}"``, and assuming that +the actual recipe name was ``emgd_1.10.bb``, the following string would +enable that package as well as the original ``gst-plugins-ugly`` +package:: + + LICENSE_FLAGS_ACCEPTED = "commercial_gst-plugins-ugly license_emgd_1.10" + +As a convenience, you do not need to specify the +complete license string for every package. You can use +an abbreviated form, which consists of just the first portion or +portions of the license string before the initial underscore character +or characters. A partial string will match any license that contains the +given string as the first portion of its license. For example, the +following value will also match both of the packages +previously mentioned as well as any other packages that have licenses +starting with "commercial" or "license":: + + LICENSE_FLAGS_ACCEPTED = "commercial license" + +License Flag Matching +--------------------- + +License flag matching allows you to control what recipes the +OpenEmbedded build system includes in the build. Fundamentally, the +build system attempts to match :term:`LICENSE_FLAGS` strings found in +recipes against strings found in :term:`LICENSE_FLAGS_ACCEPTED`. +A match causes the build system to include a recipe in the +build, while failure to find a match causes the build system to exclude +a recipe. + +In general, license flag matching is simple. However, understanding some +concepts will help you correctly and effectively use matching. + +Before a flag defined by a particular recipe is tested against the +entries of :term:`LICENSE_FLAGS_ACCEPTED`, the expanded +string ``_${PN}`` is appended to the flag. This expansion makes each +:term:`LICENSE_FLAGS` value recipe-specific. After expansion, the +string is then matched against the entries. Thus, specifying +``LICENSE_FLAGS = "commercial"`` in recipe "foo", for example, results +in the string ``"commercial_foo"``. And, to create a match, that string +must appear among the entries of :term:`LICENSE_FLAGS_ACCEPTED`. + +Judicious use of the :term:`LICENSE_FLAGS` strings and the contents of the +:term:`LICENSE_FLAGS_ACCEPTED` variable allows you a lot of flexibility for +including or excluding recipes based on licensing. For example, you can +broaden the matching capabilities by using license flags string subsets +in :term:`LICENSE_FLAGS_ACCEPTED`. + +.. note:: + + When using a string subset, be sure to use the part of the expanded + string that precedes the appended underscore character (e.g. + ``usethispart_1.3``, ``usethispart_1.4``, and so forth). + +For example, simply specifying the string "commercial" in the +:term:`LICENSE_FLAGS_ACCEPTED` variable matches any expanded +:term:`LICENSE_FLAGS` definition that starts with the string +"commercial" such as "commercial_foo" and "commercial_bar", which +are the strings the build system automatically generates for +hypothetical recipes named "foo" and "bar" assuming those recipes simply +specify the following:: + + LICENSE_FLAGS = "commercial" + +Thus, you can choose to exhaustively enumerate each license flag in the +list and allow only specific recipes into the image, or you can use a +string subset that causes a broader range of matches to allow a range of +recipes into the image. + +This scheme works even if the :term:`LICENSE_FLAGS` string already has +``_${PN}`` appended. For example, the build system turns the license +flag "commercial_1.2_foo" into "commercial_1.2_foo_foo" and would match +both the general "commercial" and the specific "commercial_1.2_foo" +strings found in the :term:`LICENSE_FLAGS_ACCEPTED` variable, as expected. + +Here are some other scenarios: + +- You can specify a versioned string in the recipe such as + "commercial_foo_1.2" in a "foo" recipe. The build system expands this + string to "commercial_foo_1.2_foo". Combine this license flag with a + :term:`LICENSE_FLAGS_ACCEPTED` variable that has the string + "commercial" and you match the flag along with any other flag that + starts with the string "commercial". + +- Under the same circumstances, you can add "commercial_foo" in the + :term:`LICENSE_FLAGS_ACCEPTED` variable and the build system not only + matches "commercial_foo_1.2" but also matches any license flag with + the string "commercial_foo", regardless of the version. + +- You can be very specific and use both the package and version parts + in the :term:`LICENSE_FLAGS_ACCEPTED` list (e.g. + "commercial_foo_1.2") to specifically match a versioned recipe. + +Other Variables Related to Commercial Licenses +---------------------------------------------- + +There are other helpful variables related to commercial license handling, +defined in the +``poky/meta/conf/distro/include/default-distrovars.inc`` file:: + + COMMERCIAL_AUDIO_PLUGINS ?= "" + COMMERCIAL_VIDEO_PLUGINS ?= "" + +If you want to enable these components, you can do so by making sure you have +statements similar to the following in your ``local.conf`` configuration file:: + + COMMERCIAL_AUDIO_PLUGINS = "gst-plugins-ugly-mad \ + gst-plugins-ugly-mpegaudioparse" + COMMERCIAL_VIDEO_PLUGINS = "gst-plugins-ugly-mpeg2dec \ + gst-plugins-ugly-mpegstream gst-plugins-bad-mpegvideoparse" + LICENSE_FLAGS_ACCEPTED = "commercial_gst-plugins-ugly commercial_gst-plugins-bad commercial_qmmp" + +Of course, you could also create a matching list for those components using the +more general "commercial" string in the :term:`LICENSE_FLAGS_ACCEPTED` variable, +but that would also enable all the other packages with :term:`LICENSE_FLAGS` +containing "commercial", which you may or may not want:: + + LICENSE_FLAGS_ACCEPTED = "commercial" + +Specifying audio and video plugins as part of the +:term:`COMMERCIAL_AUDIO_PLUGINS` and :term:`COMMERCIAL_VIDEO_PLUGINS` statements +(along with :term:`LICENSE_FLAGS_ACCEPTED`) includes the plugins or +components into built images, thus adding support for media formats or +components. + +.. note:: + + GStreamer "ugly" and "bad" plugins are actually available through + open source licenses. However, the "ugly" ones can be subject to software + patents in some countries, making it necessary to pay licensing fees + to distribute them. The "bad" ones are just deemed unreliable by the + GStreamer community and should therefore be used with care. + +Maintaining Open Source License Compliance During Your Product's Lifecycle +========================================================================== + +One of the concerns for a development organization using open source +software is how to maintain compliance with various open source +licensing during the lifecycle of the product. While this section does +not provide legal advice or comprehensively cover all scenarios, it does +present methods that you can use to assist you in meeting the compliance +requirements during a software release. + +With hundreds of different open source licenses that the Yocto Project +tracks, it is difficult to know the requirements of each and every +license. However, the requirements of the major FLOSS licenses can begin +to be covered by assuming that there are three main areas of concern: + +- Source code must be provided. + +- License text for the software must be provided. + +- Compilation scripts and modifications to the source code must be + provided. + +- spdx files can be provided. + +There are other requirements beyond the scope of these three and the +methods described in this section (e.g. the mechanism through which +source code is distributed). + +As different organizations have different methods of complying with open +source licensing, this section is not meant to imply that there is only +one single way to meet your compliance obligations, but rather to +describe one method of achieving compliance. The remainder of this +section describes methods supported to meet the previously mentioned +three requirements. Once you take steps to meet these requirements, and +prior to releasing images, sources, and the build system, you should +audit all artifacts to ensure completeness. + +.. note:: + + The Yocto Project generates a license manifest during image creation + that is located in ``${DEPLOY_DIR}/licenses/``\ `image_name`\ ``-``\ `datestamp` + to assist with any audits. + +Providing the Source Code +------------------------- + +Compliance activities should begin before you generate the final image. +The first thing you should look at is the requirement that tops the list +for most compliance groups --- providing the source. The Yocto Project has +a few ways of meeting this requirement. + +One of the easiest ways to meet this requirement is to provide the +entire :term:`DL_DIR` used by the +build. This method, however, has a few issues. The most obvious is the +size of the directory since it includes all sources used in the build +and not just the source used in the released image. It will include +toolchain source, and other artifacts, which you would not generally +release. However, the more serious issue for most companies is +accidental release of proprietary software. The Yocto Project provides +an :ref:`ref-classes-archiver` class to help avoid some of these concerns. + +Before you employ :term:`DL_DIR` or the :ref:`ref-classes-archiver` class, you +need to decide how you choose to provide source. The source +:ref:`ref-classes-archiver` class can generate tarballs and SRPMs and can +create them with various levels of compliance in mind. + +One way of doing this (but certainly not the only way) is to release +just the source as a tarball. You can do this by adding the following to +the ``local.conf`` file found in the :term:`Build Directory`:: + + INHERIT += "archiver" + ARCHIVER_MODE[src] = "original" + +During the creation of your +image, the source from all recipes that deploy packages to the image is +placed within subdirectories of ``DEPLOY_DIR/sources`` based on the +:term:`LICENSE` for each recipe. +Releasing the entire directory enables you to comply with requirements +concerning providing the unmodified source. It is important to note that +the size of the directory can get large. + +A way to help mitigate the size issue is to only release tarballs for +licenses that require the release of source. Let us assume you are only +concerned with GPL code as identified by running the following script: + +.. code-block:: shell + + # Script to archive a subset of packages matching specific license(s) + # Source and license files are copied into sub folders of package folder + # Must be run from build folder + #!/bin/bash + src_release_dir="source-release" + mkdir -p $src_release_dir + for a in tmp/deploy/sources/*; do + for d in $a/*; do + # Get package name from path + p=`basename $d` + p=${p%-*} + p=${p%-*} + # Only archive GPL packages (update *GPL* regex for your license check) + numfiles=`ls tmp/deploy/licenses/$p/*GPL* 2> /dev/null | wc -l` + if [ $numfiles -ge 1 ]; then + echo Archiving $p + mkdir -p $src_release_dir/$p/source + cp $d/* $src_release_dir/$p/source 2> /dev/null + mkdir -p $src_release_dir/$p/license + cp tmp/deploy/licenses/$p/* $src_release_dir/$p/license 2> /dev/null + fi + done + done + +At this point, you +could create a tarball from the ``gpl_source_release`` directory and +provide that to the end user. This method would be a step toward +achieving compliance with section 3a of GPLv2 and with section 6 of +GPLv3. + +Providing License Text +~~~~~~~~~~~~~~~~~~~~~~ + +One requirement that is often overlooked is inclusion of license text. +This requirement also needs to be dealt with prior to generating the +final image. Some licenses require the license text to accompany the +binary. You can achieve this by adding the following to your +``local.conf`` file:: + + COPY_LIC_MANIFEST = "1" + COPY_LIC_DIRS = "1" + LICENSE_CREATE_PACKAGE = "1" + +Adding these statements to the +configuration file ensures that the licenses collected during package +generation are included on your image. + +.. note:: + + Setting all three variables to "1" results in the image having two + copies of the same license file. One copy resides in + ``/usr/share/common-licenses`` and the other resides in + ``/usr/share/license``. + + The reason for this behavior is because + :term:`COPY_LIC_DIRS` and + :term:`COPY_LIC_MANIFEST` + add a copy of the license when the image is built but do not offer a + path for adding licenses for newly installed packages to an image. + :term:`LICENSE_CREATE_PACKAGE` + adds a separate package and an upgrade path for adding licenses to an + image. + +As the source :ref:`ref-classes-archiver` class has already archived the +original unmodified source that contains the license files, you would have +already met the requirements for inclusion of the license information +with source as defined by the GPL and other open source licenses. + +Providing Compilation Scripts and Source Code Modifications +----------------------------------------------------------- + +At this point, we have addressed all we need to prior to generating the +image. The next two requirements are addressed during the final +packaging of the release. + +By releasing the version of the OpenEmbedded build system and the layers +used during the build, you will be providing both compilation scripts +and the source code modifications in one step. + +If the deployment team has a :ref:`overview-manual/concepts:bsp layer` +and a distro layer, and those +those layers are used to patch, compile, package, or modify (in any way) +any open source software included in your released images, you might be +required to release those layers under section 3 of GPLv2 or section 1 +of GPLv3. One way of doing that is with a clean checkout of the version +of the Yocto Project and layers used during your build. Here is an +example: + +.. code-block:: shell + + # We built using the dunfell branch of the poky repo + $ git clone -b dunfell git://git.yoctoproject.org/poky + $ cd poky + # We built using the release_branch for our layers + $ git clone -b release_branch git://git.mycompany.com/meta-my-bsp-layer + $ git clone -b release_branch git://git.mycompany.com/meta-my-software-layer + # clean up the .git repos + $ find . -name ".git" -type d -exec rm -rf {} \; + +One +thing a development organization might want to consider for end-user +convenience is to modify ``meta-poky/conf/bblayers.conf.sample`` to +ensure that when the end user utilizes the released build system to +build an image, the development organization's layers are included in +the ``bblayers.conf`` file automatically:: + + # POKY_BBLAYERS_CONF_VERSION is increased each time build/conf/bblayers.conf + # changes incompatibly + POKY_BBLAYERS_CONF_VERSION = "2" + + BBPATH = "${TOPDIR}" + BBFILES ?= "" + + BBLAYERS ?= " \ + ##OEROOT##/meta \ + ##OEROOT##/meta-poky \ + ##OEROOT##/meta-yocto-bsp \ + ##OEROOT##/meta-mylayer \ + " + +Creating and +providing an archive of the :term:`Metadata` +layers (recipes, configuration files, and so forth) enables you to meet +your requirements to include the scripts to control compilation as well +as any modifications to the original source. + +Compliance Limitations with Executables Built from Static Libraries +------------------------------------------------------------------- + +When package A is added to an image via the :term:`RDEPENDS` or :term:`RRECOMMENDS` +mechanisms as well as explicitly included in the image recipe with +:term:`IMAGE_INSTALL`, and depends on a static linked library recipe B +(``DEPENDS += "B"``), package B will neither appear in the generated license +manifest nor in the generated source tarballs. This occurs as the +:ref:`ref-classes-license` and :ref:`ref-classes-archiver` classes assume that +only packages included via :term:`RDEPENDS` or :term:`RRECOMMENDS` +end up in the image. + +As a result, potential obligations regarding license compliance for package B +may not be met. + +The Yocto Project doesn't enable static libraries by default, in part because +of this issue. Before a solution to this limitation is found, you need to +keep in mind that if your root filesystem is built from static libraries, +you will need to manually ensure that your deliveries are compliant +with the licenses of these libraries. + +Copying Non Standard Licenses +============================= + +Some packages, such as the linux-firmware package, have many licenses +that are not in any way common. You can avoid adding a lot of these +types of common license files, which are only applicable to a specific +package, by using the +:term:`NO_GENERIC_LICENSE` +variable. Using this variable also avoids QA errors when you use a +non-common, non-CLOSED license in a recipe. + +Here is an example that uses the ``LICENSE.Abilis.txt`` file as +the license from the fetched source:: + + NO_GENERIC_LICENSE[Firmware-Abilis] = "LICENSE.Abilis.txt" + diff --git a/documentation/dev-manual/new-machine.rst b/documentation/dev-manual/new-machine.rst new file mode 100644 index 0000000000..b7978f4ba9 --- /dev/null +++ b/documentation/dev-manual/new-machine.rst @@ -0,0 +1,118 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Adding a New Machine +==================== + +Adding a new machine to the Yocto Project is a straightforward process. +This section describes how to add machines that are similar to those +that the Yocto Project already supports. + +.. note:: + + Although well within the capabilities of the Yocto Project, adding a + totally new architecture might require changes to ``gcc``/``glibc`` + and to the site information, which is beyond the scope of this + manual. + +For a complete example that shows how to add a new machine, see the +":ref:`bsp-guide/bsp:creating a new bsp layer using the \`\`bitbake-layers\`\` script`" +section in the Yocto Project Board Support Package (BSP) Developer's +Guide. + +Adding the Machine Configuration File +===================================== + +To add a new machine, you need to add a new machine configuration file +to the layer's ``conf/machine`` directory. This configuration file +provides details about the device you are adding. + +The OpenEmbedded build system uses the root name of the machine +configuration file to reference the new machine. For example, given a +machine configuration file named ``crownbay.conf``, the build system +recognizes the machine as "crownbay". + +The most important variables you must set in your machine configuration +file or include from a lower-level configuration file are as follows: + +- :term:`TARGET_ARCH` (e.g. "arm") + +- ``PREFERRED_PROVIDER_virtual/kernel`` + +- :term:`MACHINE_FEATURES` (e.g. "apm screen wifi") + +You might also need these variables: + +- :term:`SERIAL_CONSOLES` (e.g. "115200;ttyS0 115200;ttyS1") + +- :term:`KERNEL_IMAGETYPE` (e.g. "zImage") + +- :term:`IMAGE_FSTYPES` (e.g. "tar.gz jffs2") + +You can find full details on these variables in the reference section. +You can leverage existing machine ``.conf`` files from +``meta-yocto-bsp/conf/machine/``. + +Adding a Kernel for the Machine +=============================== + +The OpenEmbedded build system needs to be able to build a kernel for the +machine. You need to either create a new kernel recipe for this machine, +or extend an existing kernel recipe. You can find several kernel recipe +examples in the Source Directory at ``meta/recipes-kernel/linux`` that +you can use as references. + +If you are creating a new kernel recipe, normal recipe-writing rules +apply for setting up a :term:`SRC_URI`. Thus, you need to specify any +necessary patches and set :term:`S` to point at the source code. You need to +create a :ref:`ref-tasks-configure` task that configures the unpacked kernel with +a ``defconfig`` file. You can do this by using a ``make defconfig`` +command or, more commonly, by copying in a suitable ``defconfig`` file +and then running ``make oldconfig``. By making use of ``inherit kernel`` +and potentially some of the ``linux-*.inc`` files, most other +functionality is centralized and the defaults of the class normally work +well. + +If you are extending an existing kernel recipe, it is usually a matter +of adding a suitable ``defconfig`` file. The file needs to be added into +a location similar to ``defconfig`` files used for other machines in a +given kernel recipe. A possible way to do this is by listing the file in +the :term:`SRC_URI` and adding the machine to the expression in +:term:`COMPATIBLE_MACHINE`:: + + COMPATIBLE_MACHINE = '(qemux86|qemumips)' + +For more information on ``defconfig`` files, see the +":ref:`kernel-dev/common:changing the configuration`" +section in the Yocto Project Linux Kernel Development Manual. + +Adding a Formfactor Configuration File +====================================== + +A formfactor configuration file provides information about the target +hardware for which the image is being built and information that the +build system cannot obtain from other sources such as the kernel. Some +examples of information contained in a formfactor configuration file +include framebuffer orientation, whether or not the system has a +keyboard, the positioning of the keyboard in relation to the screen, and +the screen resolution. + +The build system uses reasonable defaults in most cases. However, if +customization is necessary, you need to create a ``machconfig`` file in +the ``meta/recipes-bsp/formfactor/files`` directory. This directory +contains directories for specific machines such as ``qemuarm`` and +``qemux86``. For information about the settings available and the +defaults, see the ``meta/recipes-bsp/formfactor/files/config`` file +found in the same area. + +Following is an example for "qemuarm" machine:: + + HAVE_TOUCHSCREEN=1 + HAVE_KEYBOARD=1 + DISPLAY_CAN_ROTATE=0 + DISPLAY_ORIENTATION=0 + #DISPLAY_WIDTH_PIXELS=640 + #DISPLAY_HEIGHT_PIXELS=480 + #DISPLAY_BPP=16 + DISPLAY_DPI=150 + DISPLAY_SUBPIXEL_ORDER=vrgb + diff --git a/documentation/dev-manual/new-recipe.rst b/documentation/dev-manual/new-recipe.rst new file mode 100644 index 0000000000..2c1101ec2b --- /dev/null +++ b/documentation/dev-manual/new-recipe.rst @@ -0,0 +1,1634 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Writing a New Recipe +******************** + +Recipes (``.bb`` files) are fundamental components in the Yocto Project +environment. Each software component built by the OpenEmbedded build +system requires a recipe to define the component. This section describes +how to create, write, and test a new recipe. + +.. note:: + + For information on variables that are useful for recipes and for + information about recipe naming issues, see the + ":ref:`ref-manual/varlocality:recipes`" section of the Yocto Project + Reference Manual. + +Overview +======== + +The following figure shows the basic process for creating a new recipe. +The remainder of the section provides details for the steps. + +.. image:: figures/recipe-workflow.png + :align: center + :width: 50% + +Locate or Automatically Create a Base Recipe +============================================ + +You can always write a recipe from scratch. However, there are three choices +that can help you quickly get started with a new recipe: + +- ``devtool add``: A command that assists in creating a recipe and an + environment conducive to development. + +- ``recipetool create``: A command provided by the Yocto Project that + automates creation of a base recipe based on the source files. + +- *Existing Recipes:* Location and modification of an existing recipe + that is similar in function to the recipe you need. + +.. note:: + + For information on recipe syntax, see the + ":ref:`dev-manual/new-recipe:recipe syntax`" section. + +Creating the Base Recipe Using ``devtool add`` +---------------------------------------------- + +The ``devtool add`` command uses the same logic for auto-creating the +recipe as ``recipetool create``, which is listed below. Additionally, +however, ``devtool add`` sets up an environment that makes it easy for +you to patch the source and to make changes to the recipe as is often +necessary when adding a recipe to build a new piece of software to be +included in a build. + +You can find a complete description of the ``devtool add`` command in +the ":ref:`sdk-manual/extensible:a closer look at \`\`devtool add\`\``" section +in the Yocto Project Application Development and the Extensible Software +Development Kit (eSDK) manual. + +Creating the Base Recipe Using ``recipetool create`` +---------------------------------------------------- + +``recipetool create`` automates creation of a base recipe given a set of +source code files. As long as you can extract or point to the source +files, the tool will construct a recipe and automatically configure all +pre-build information into the recipe. For example, suppose you have an +application that builds using Autotools. Creating the base recipe using +``recipetool`` results in a recipe that has the pre-build dependencies, +license requirements, and checksums configured. + +To run the tool, you just need to be in your :term:`Build Directory` and +have sourced the build environment setup script (i.e. +:ref:`structure-core-script`). To get help on the tool, use the following +command:: + + $ recipetool -h + NOTE: Starting bitbake server... + usage: recipetool [-d] [-q] [--color COLOR] [-h] ... + + OpenEmbedded recipe tool + + options: + -d, --debug Enable debug output + -q, --quiet Print only errors + --color COLOR Colorize output (where COLOR is auto, always, never) + -h, --help show this help message and exit + + subcommands: + create Create a new recipe + newappend Create a bbappend for the specified target in the specified + layer + setvar Set a variable within a recipe + appendfile Create/update a bbappend to replace a target file + appendsrcfiles Create/update a bbappend to add or replace source files + appendsrcfile Create/update a bbappend to add or replace a source file + Use recipetool --help to get help on a specific command + +Running ``recipetool create -o OUTFILE`` creates the base recipe and +locates it properly in the layer that contains your source files. +Following are some syntax examples: + + - Use this syntax to generate a recipe based on source. Once generated, + the recipe resides in the existing source code layer:: + + recipetool create -o OUTFILE source + + - Use this syntax to generate a recipe using code that + you extract from source. The extracted code is placed in its own layer + defined by :term:`EXTERNALSRC`:: + + recipetool create -o OUTFILE -x EXTERNALSRC source + + - Use this syntax to generate a recipe based on source. The options + direct ``recipetool`` to generate debugging information. Once generated, + the recipe resides in the existing source code layer:: + + recipetool create -d -o OUTFILE source + +Locating and Using a Similar Recipe +----------------------------------- + +Before writing a recipe from scratch, it is often useful to discover +whether someone else has already written one that meets (or comes close +to meeting) your needs. The Yocto Project and OpenEmbedded communities +maintain many recipes that might be candidates for what you are doing. +You can find a good central index of these recipes in the +:oe_layerindex:`OpenEmbedded Layer Index <>`. + +Working from an existing recipe or a skeleton recipe is the best way to +get started. Here are some points on both methods: + +- *Locate and modify a recipe that is close to what you want to do:* + This method works when you are familiar with the current recipe + space. The method does not work so well for those new to the Yocto + Project or writing recipes. + + Some risks associated with this method are using a recipe that has + areas totally unrelated to what you are trying to accomplish with + your recipe, not recognizing areas of the recipe that you might have + to add from scratch, and so forth. All these risks stem from + unfamiliarity with the existing recipe space. + +- *Use and modify the following skeleton recipe:* If for some reason + you do not want to use ``recipetool`` and you cannot find an existing + recipe that is close to meeting your needs, you can use the following + structure to provide the fundamental areas of a new recipe:: + + DESCRIPTION = "" + HOMEPAGE = "" + LICENSE = "" + SECTION = "" + DEPENDS = "" + LIC_FILES_CHKSUM = "" + + SRC_URI = "" + +Storing and Naming the Recipe +============================= + +Once you have your base recipe, you should put it in your own layer and +name it appropriately. Locating it correctly ensures that the +OpenEmbedded build system can find it when you use BitBake to process +the recipe. + +- *Storing Your Recipe:* The OpenEmbedded build system locates your + recipe through the layer's ``conf/layer.conf`` file and the + :term:`BBFILES` variable. This + variable sets up a path from which the build system can locate + recipes. Here is the typical use:: + + BBFILES += "${LAYERDIR}/recipes-*/*/*.bb \ + ${LAYERDIR}/recipes-*/*/*.bbappend" + + Consequently, you need to be sure you locate your new recipe inside + your layer such that it can be found. + + You can find more information on how layers are structured in the + ":ref:`dev-manual/layers:understanding and creating layers`" section. + +- *Naming Your Recipe:* When you name your recipe, you need to follow + this naming convention:: + + basename_version.bb + + Use lower-cased characters and do not include the reserved suffixes + ``-native``, ``-cross``, ``-initial``, or ``-dev`` casually (i.e. do not use + them as part of your recipe name unless the string applies). Here are some + examples: + + .. code-block:: none + + cups_1.7.0.bb + gawk_4.0.2.bb + irssi_0.8.16-rc1.bb + +Running a Build on the Recipe +============================= + +Creating a new recipe is usually an iterative process that requires +using BitBake to process the recipe multiple times in order to +progressively discover and add information to the recipe file. + +Assuming you have sourced the build environment setup script (i.e. +:ref:`structure-core-script`) and you are in the :term:`Build Directory`, use +BitBake to process your recipe. All you need to provide is the +``basename`` of the recipe as described in the previous section:: + + $ bitbake basename + +During the build, the OpenEmbedded build system creates a temporary work +directory for each recipe +(``${``\ :term:`WORKDIR`\ ``}``) +where it keeps extracted source files, log files, intermediate +compilation and packaging files, and so forth. + +The path to the per-recipe temporary work directory depends on the +context in which it is being built. The quickest way to find this path +is to have BitBake return it by running the following:: + + $ bitbake -e basename | grep ^WORKDIR= + +As an example, assume a Source Directory +top-level folder named ``poky``, a default :term:`Build Directory` at +``poky/build``, and a ``qemux86-poky-linux`` machine target system. +Furthermore, suppose your recipe is named ``foo_1.3.0.bb``. In this +case, the work directory the build system uses to build the package +would be as follows:: + + poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0 + +Inside this directory you can find sub-directories such as ``image``, +``packages-split``, and ``temp``. After the build, you can examine these +to determine how well the build went. + +.. note:: + + You can find log files for each task in the recipe's ``temp`` + directory (e.g. ``poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0/temp``). + Log files are named ``log.taskname`` (e.g. ``log.do_configure``, + ``log.do_fetch``, and ``log.do_compile``). + +You can find more information about the build process in +":doc:`/overview-manual/development-environment`" +chapter of the Yocto Project Overview and Concepts Manual. + +Fetching Code +============= + +The first thing your recipe must do is specify how to fetch the source +files. Fetching is controlled mainly through the +:term:`SRC_URI` variable. Your recipe +must have a :term:`SRC_URI` variable that points to where the source is +located. For a graphical representation of source locations, see the +":ref:`overview-manual/concepts:sources`" section in +the Yocto Project Overview and Concepts Manual. + +The :ref:`ref-tasks-fetch` task uses the prefix of each entry in the +:term:`SRC_URI` variable value to determine which +:ref:`fetcher ` +to use to get your source files. It is the :term:`SRC_URI` variable that triggers +the fetcher. The :ref:`ref-tasks-patch` task uses the variable after source is +fetched to apply patches. The OpenEmbedded build system uses +:term:`FILESOVERRIDES` for scanning directory locations for local files in +:term:`SRC_URI`. + +The :term:`SRC_URI` variable in your recipe must define each unique location +for your source files. It is good practice to not hard-code version +numbers in a URL used in :term:`SRC_URI`. Rather than hard-code these +values, use ``${``\ :term:`PV`\ ``}``, +which causes the fetch process to use the version specified in the +recipe filename. Specifying the version in this manner means that +upgrading the recipe to a future version is as simple as renaming the +recipe to match the new version. + +Here is a simple example from the +``meta/recipes-devtools/strace/strace_5.5.bb`` recipe where the source +comes from a single tarball. Notice the use of the +:term:`PV` variable:: + + SRC_URI = "https://strace.io/files/${PV}/strace-${PV}.tar.xz \ + +Files mentioned in :term:`SRC_URI` whose names end in a typical archive +extension (e.g. ``.tar``, ``.tar.gz``, ``.tar.bz2``, ``.zip``, and so +forth), are automatically extracted during the +:ref:`ref-tasks-unpack` task. For +another example that specifies these types of files, see the +":ref:`dev-manual/new-recipe:building an autotooled package`" section. + +Another way of specifying source is from an SCM. For Git repositories, +you must specify :term:`SRCREV` and you should specify :term:`PV` to include +the revision with :term:`SRCPV`. Here is an example from the recipe +``meta/recipes-core/musl/gcompat_git.bb``:: + + SRC_URI = "git://git.adelielinux.org/adelie/gcompat.git;protocol=https;branch=current" + + PV = "1.0.0+1.1+git${SRCPV}" + SRCREV = "af5a49e489fdc04b9cf02547650d7aeaccd43793" + +If your :term:`SRC_URI` statement includes URLs pointing to individual files +fetched from a remote server other than a version control system, +BitBake attempts to verify the files against checksums defined in your +recipe to ensure they have not been tampered with or otherwise modified +since the recipe was written. Two checksums are used: +``SRC_URI[md5sum]`` and ``SRC_URI[sha256sum]``. + +If your :term:`SRC_URI` variable points to more than a single URL (excluding +SCM URLs), you need to provide the ``md5`` and ``sha256`` checksums for +each URL. For these cases, you provide a name for each URL as part of +the :term:`SRC_URI` and then reference that name in the subsequent checksum +statements. Here is an example combining lines from the files +``git.inc`` and ``git_2.24.1.bb``:: + + SRC_URI = "${KERNELORG_MIRROR}/software/scm/git/git-${PV}.tar.gz;name=tarball \ + ${KERNELORG_MIRROR}/software/scm/git/git-manpages-${PV}.tar.gz;name=manpages" + + SRC_URI[tarball.md5sum] = "166bde96adbbc11c8843d4f8f4f9811b" + SRC_URI[tarball.sha256sum] = "ad5334956301c86841eb1e5b1bb20884a6bad89a10a6762c958220c7cf64da02" + SRC_URI[manpages.md5sum] = "31c2272a8979022497ba3d4202df145d" + SRC_URI[manpages.sha256sum] = "9a7ae3a093bea39770eb96ca3e5b40bff7af0b9f6123f089d7821d0e5b8e1230" + +Proper values for ``md5`` and ``sha256`` checksums might be available +with other signatures on the download page for the upstream source (e.g. +``md5``, ``sha1``, ``sha256``, ``GPG``, and so forth). Because the +OpenEmbedded build system only deals with ``sha256sum`` and ``md5sum``, +you should verify all the signatures you find by hand. + +If no :term:`SRC_URI` checksums are specified when you attempt to build the +recipe, or you provide an incorrect checksum, the build will produce an +error for each missing or incorrect checksum. As part of the error +message, the build system provides the checksum string corresponding to +the fetched file. Once you have the correct checksums, you can copy and +paste them into your recipe and then run the build again to continue. + +.. note:: + + As mentioned, if the upstream source provides signatures for + verifying the downloaded source code, you should verify those + manually before setting the checksum values in the recipe and + continuing with the build. + +This final example is a bit more complicated and is from the +``meta/recipes-sato/rxvt-unicode/rxvt-unicode_9.20.bb`` recipe. The +example's :term:`SRC_URI` statement identifies multiple files as the source +files for the recipe: a tarball, a patch file, a desktop file, and an icon:: + + SRC_URI = "http://dist.schmorp.de/rxvt-unicode/Attic/rxvt-unicode-${PV}.tar.bz2 \ + file://xwc.patch \ + file://rxvt.desktop \ + file://rxvt.png" + +When you specify local files using the ``file://`` URI protocol, the +build system fetches files from the local machine. The path is relative +to the :term:`FILESPATH` variable +and searches specific directories in a certain order: +``${``\ :term:`BP`\ ``}``, +``${``\ :term:`BPN`\ ``}``, and +``files``. The directories are assumed to be subdirectories of the +directory in which the recipe or append file resides. For another +example that specifies these types of files, see the +"`building a single .c file package`_" section. + +The previous example also specifies a patch file. Patch files are files +whose names usually end in ``.patch`` or ``.diff`` but can end with +compressed suffixes such as ``diff.gz`` and ``patch.bz2``, for example. +The build system automatically applies patches as described in the +":ref:`dev-manual/new-recipe:patching code`" section. + +Fetching Code Through Firewalls +------------------------------- + +Some users are behind firewalls and need to fetch code through a proxy. +See the ":doc:`/ref-manual/faq`" chapter for advice. + +Limiting the Number of Parallel Connections +------------------------------------------- + +Some users are behind firewalls or use servers where the number of parallel +connections is limited. In such cases, you can limit the number of fetch +tasks being run in parallel by adding the following to your ``local.conf`` +file:: + + do_fetch[number_threads] = "4" + +Unpacking Code +============== + +During the build, the +:ref:`ref-tasks-unpack` task unpacks +the source with ``${``\ :term:`S`\ ``}`` +pointing to where it is unpacked. + +If you are fetching your source files from an upstream source archived +tarball and the tarball's internal structure matches the common +convention of a top-level subdirectory named +``${``\ :term:`BPN`\ ``}-${``\ :term:`PV`\ ``}``, +then you do not need to set :term:`S`. However, if :term:`SRC_URI` specifies to +fetch source from an archive that does not use this convention, or from +an SCM like Git or Subversion, your recipe needs to define :term:`S`. + +If processing your recipe using BitBake successfully unpacks the source +files, you need to be sure that the directory pointed to by ``${S}`` +matches the structure of the source. + +Patching Code +============= + +Sometimes it is necessary to patch code after it has been fetched. Any +files mentioned in :term:`SRC_URI` whose names end in ``.patch`` or +``.diff`` or compressed versions of these suffixes (e.g. ``diff.gz`` are +treated as patches. The +:ref:`ref-tasks-patch` task +automatically applies these patches. + +The build system should be able to apply patches with the "-p1" option +(i.e. one directory level in the path will be stripped off). If your +patch needs to have more directory levels stripped off, specify the +number of levels using the "striplevel" option in the :term:`SRC_URI` entry +for the patch. Alternatively, if your patch needs to be applied in a +specific subdirectory that is not specified in the patch file, use the +"patchdir" option in the entry. + +As with all local files referenced in +:term:`SRC_URI` using ``file://``, +you should place patch files in a directory next to the recipe either +named the same as the base name of the recipe +(:term:`BP` and +:term:`BPN`) or "files". + +Licensing +========= + +Your recipe needs to define variables related to the license +under whith the software is distributed. See the +:ref:`contributor-guide/recipe-style-guide:recipe license fields` +section in the Contributor Guide for details. + +Dependencies +============ + +Most software packages have a short list of other packages that they +require, which are called dependencies. These dependencies fall into two +main categories: build-time dependencies, which are required when the +software is built; and runtime dependencies, which are required to be +installed on the target in order for the software to run. + +Within a recipe, you specify build-time dependencies using the +:term:`DEPENDS` variable. Although there are nuances, +items specified in :term:`DEPENDS` should be names of other +recipes. It is important that you specify all build-time dependencies +explicitly. + +Another consideration is that configure scripts might automatically +check for optional dependencies and enable corresponding functionality +if those dependencies are found. If you wish to make a recipe that is +more generally useful (e.g. publish the recipe in a layer for others to +use), instead of hard-disabling the functionality, you can use the +:term:`PACKAGECONFIG` variable to allow functionality and the +corresponding dependencies to be enabled and disabled easily by other +users of the recipe. + +Similar to build-time dependencies, you specify runtime dependencies +through a variable - +:term:`RDEPENDS`, which is +package-specific. All variables that are package-specific need to have +the name of the package added to the end as an override. Since the main +package for a recipe has the same name as the recipe, and the recipe's +name can be found through the +``${``\ :term:`PN`\ ``}`` variable, then +you specify the dependencies for the main package by setting +``RDEPENDS:${PN}``. If the package were named ``${PN}-tools``, then you +would set ``RDEPENDS:${PN}-tools``, and so forth. + +Some runtime dependencies will be set automatically at packaging time. +These dependencies include any shared library dependencies (i.e. if a +package "example" contains "libexample" and another package "mypackage" +contains a binary that links to "libexample" then the OpenEmbedded build +system will automatically add a runtime dependency to "mypackage" on +"example"). See the +":ref:`overview-manual/concepts:automatically added runtime dependencies`" +section in the Yocto Project Overview and Concepts Manual for further +details. + +Configuring the Recipe +====================== + +Most software provides some means of setting build-time configuration +options before compilation. Typically, setting these options is +accomplished by running a configure script with options, or by modifying +a build configuration file. + +.. note:: + + As of Yocto Project Release 1.7, some of the core recipes that + package binary configuration scripts now disable the scripts due to + the scripts previously requiring error-prone path substitution. The + OpenEmbedded build system uses ``pkg-config`` now, which is much more + robust. You can find a list of the ``*-config`` scripts that are disabled + in the ":ref:`migration-1.7-binary-configuration-scripts-disabled`" section + in the Yocto Project Reference Manual. + +A major part of build-time configuration is about checking for +build-time dependencies and possibly enabling optional functionality as +a result. You need to specify any build-time dependencies for the +software you are building in your recipe's +:term:`DEPENDS` value, in terms of +other recipes that satisfy those dependencies. You can often find +build-time or runtime dependencies described in the software's +documentation. + +The following list provides configuration items of note based on how +your software is built: + +- *Autotools:* If your source files have a ``configure.ac`` file, then + your software is built using Autotools. If this is the case, you just + need to modify the configuration. + + When using Autotools, your recipe needs to inherit the + :ref:`ref-classes-autotools` class and it does not have to + contain a :ref:`ref-tasks-configure` task. However, you might still want to + make some adjustments. For example, you can set :term:`EXTRA_OECONF` or + :term:`PACKAGECONFIG_CONFARGS` to pass any needed configure options that + are specific to the recipe. + +- *CMake:* If your source files have a ``CMakeLists.txt`` file, then + your software is built using CMake. If this is the case, you just + need to modify the configuration. + + When you use CMake, your recipe needs to inherit the + :ref:`ref-classes-cmake` class and it does not have to contain a + :ref:`ref-tasks-configure` task. You can make some adjustments by setting + :term:`EXTRA_OECMAKE` to pass any needed configure options that are + specific to the recipe. + + .. note:: + + If you need to install one or more custom CMake toolchain files + that are supplied by the application you are building, install the + files to ``${D}${datadir}/cmake/Modules`` during :ref:`ref-tasks-install`. + +- *Other:* If your source files do not have a ``configure.ac`` or + ``CMakeLists.txt`` file, then your software is built using some + method other than Autotools or CMake. If this is the case, you + normally need to provide a + :ref:`ref-tasks-configure` task + in your recipe unless, of course, there is nothing to configure. + + Even if your software is not being built by Autotools or CMake, you + still might not need to deal with any configuration issues. You need + to determine if configuration is even a required step. You might need + to modify a Makefile or some configuration file used for the build to + specify necessary build options. Or, perhaps you might need to run a + provided, custom configure script with the appropriate options. + + For the case involving a custom configure script, you would run + ``./configure --help`` and look for the options you need to set. + +Once configuration succeeds, it is always good practice to look at the +``log.do_configure`` file to ensure that the appropriate options have +been enabled and no additional build-time dependencies need to be added +to :term:`DEPENDS`. For example, if the configure script reports that it +found something not mentioned in :term:`DEPENDS`, or that it did not find +something that it needed for some desired optional functionality, then +you would need to add those to :term:`DEPENDS`. Looking at the log might +also reveal items being checked for, enabled, or both that you do not +want, or items not being found that are in :term:`DEPENDS`, in which case +you would need to look at passing extra options to the configure script +as needed. For reference information on configure options specific to +the software you are building, you can consult the output of the +``./configure --help`` command within ``${S}`` or consult the software's +upstream documentation. + +Using Headers to Interface with Devices +======================================= + +If your recipe builds an application that needs to communicate with some +device or needs an API into a custom kernel, you will need to provide +appropriate header files. Under no circumstances should you ever modify +the existing +``meta/recipes-kernel/linux-libc-headers/linux-libc-headers.inc`` file. +These headers are used to build ``libc`` and must not be compromised +with custom or machine-specific header information. If you customize +``libc`` through modified headers all other applications that use +``libc`` thus become affected. + +.. note:: + + Never copy and customize the ``libc`` header file (i.e. + ``meta/recipes-kernel/linux-libc-headers/linux-libc-headers.inc``). + +The correct way to interface to a device or custom kernel is to use a +separate package that provides the additional headers for the driver or +other unique interfaces. When doing so, your application also becomes +responsible for creating a dependency on that specific provider. + +Consider the following: + +- Never modify ``linux-libc-headers.inc``. Consider that file to be + part of the ``libc`` system, and not something you use to access the + kernel directly. You should access ``libc`` through specific ``libc`` + calls. + +- Applications that must talk directly to devices should either provide + necessary headers themselves, or establish a dependency on a special + headers package that is specific to that driver. + +For example, suppose you want to modify an existing header that adds I/O +control or network support. If the modifications are used by a small +number programs, providing a unique version of a header is easy and has +little impact. When doing so, bear in mind the guidelines in the +previous list. + +.. note:: + + If for some reason your changes need to modify the behavior of the ``libc``, + and subsequently all other applications on the system, use a ``.bbappend`` + to modify the ``linux-kernel-headers.inc`` file. However, take care to not + make the changes machine specific. + +Consider a case where your kernel is older and you need an older +``libc`` ABI. The headers installed by your recipe should still be a +standard mainline kernel, not your own custom one. + +When you use custom kernel headers you need to get them from +:term:`STAGING_KERNEL_DIR`, +which is the directory with kernel headers that are required to build +out-of-tree modules. Your recipe will also need the following:: + + do_configure[depends] += "virtual/kernel:do_shared_workdir" + +Compilation +=========== + +During a build, the :ref:`ref-tasks-compile` task happens after source is fetched, +unpacked, and configured. If the recipe passes through :ref:`ref-tasks-compile` +successfully, nothing needs to be done. + +However, if the compile step fails, you need to diagnose the failure. +Here are some common issues that cause failures. + +.. note:: + + For cases where improper paths are detected for configuration files + or for when libraries/headers cannot be found, be sure you are using + the more robust ``pkg-config``. See the note in section + ":ref:`dev-manual/new-recipe:Configuring the Recipe`" for additional information. + +- *Parallel build failures:* These failures manifest themselves as + intermittent errors, or errors reporting that a file or directory + that should be created by some other part of the build process could + not be found. This type of failure can occur even if, upon + inspection, the file or directory does exist after the build has + failed, because that part of the build process happened in the wrong + order. + + To fix the problem, you need to either satisfy the missing dependency + in the Makefile or whatever script produced the Makefile, or (as a + workaround) set :term:`PARALLEL_MAKE` to an empty string:: + + PARALLEL_MAKE = "" + + For information on parallel Makefile issues, see the + ":ref:`dev-manual/debugging:debugging parallel make races`" section. + +- *Improper host path usage:* This failure applies to recipes building + for the target or ":ref:`ref-classes-nativesdk`" only. The + failure occurs when the compilation process uses improper headers, + libraries, or other files from the host system when cross-compiling for + the target. + + To fix the problem, examine the ``log.do_compile`` file to identify + the host paths being used (e.g. ``/usr/include``, ``/usr/lib``, and + so forth) and then either add configure options, apply a patch, or do + both. + +- *Failure to find required libraries/headers:* If a build-time + dependency is missing because it has not been declared in + :term:`DEPENDS`, or because the + dependency exists but the path used by the build process to find the + file is incorrect and the configure step did not detect it, the + compilation process could fail. For either of these failures, the + compilation process notes that files could not be found. In these + cases, you need to go back and add additional options to the + configure script as well as possibly add additional build-time + dependencies to :term:`DEPENDS`. + + Occasionally, it is necessary to apply a patch to the source to + ensure the correct paths are used. If you need to specify paths to + find files staged into the sysroot from other recipes, use the + variables that the OpenEmbedded build system provides (e.g. + :term:`STAGING_BINDIR`, :term:`STAGING_INCDIR`, :term:`STAGING_DATADIR`, and so + forth). + +Installing +========== + +During :ref:`ref-tasks-install`, the task copies the built files along with their +hierarchy to locations that would mirror their locations on the target +device. The installation process copies files from the +``${``\ :term:`S`\ ``}``, +``${``\ :term:`B`\ ``}``, and +``${``\ :term:`WORKDIR`\ ``}`` +directories to the ``${``\ :term:`D`\ ``}`` +directory to create the structure as it should appear on the target +system. + +How your software is built affects what you must do to be sure your +software is installed correctly. The following list describes what you +must do for installation depending on the type of build system used by +the software being built: + +- *Autotools and CMake:* If the software your recipe is building uses + Autotools or CMake, the OpenEmbedded build system understands how to + install the software. Consequently, you do not have to have a + :ref:`ref-tasks-install` task as part of your recipe. You just need to make + sure the install portion of the build completes with no issues. + However, if you wish to install additional files not already being + installed by ``make install``, you should do this using a + ``do_install:append`` function using the install command as described + in the "Manual" bulleted item later in this list. + +- *Other (using* ``make install``\ *)*: You need to define a :ref:`ref-tasks-install` + function in your recipe. The function should call + ``oe_runmake install`` and will likely need to pass in the + destination directory as well. How you pass that path is dependent on + how the ``Makefile`` being run is written (e.g. ``DESTDIR=${D}``, + ``PREFIX=${D}``, ``INSTALLROOT=${D}``, and so forth). + + For an example recipe using ``make install``, see the + ":ref:`dev-manual/new-recipe:building a makefile-based package`" section. + +- *Manual:* You need to define a :ref:`ref-tasks-install` function in your + recipe. The function must first use ``install -d`` to create the + directories under + ``${``\ :term:`D`\ ``}``. Once the + directories exist, your function can use ``install`` to manually + install the built software into the directories. + + You can find more information on ``install`` at + https://www.gnu.org/software/coreutils/manual/html_node/install-invocation.html. + +For the scenarios that do not use Autotools or CMake, you need to track +the installation and diagnose and fix any issues until everything +installs correctly. You need to look in the default location of +``${D}``, which is ``${WORKDIR}/image``, to be sure your files have been +installed correctly. + +.. note:: + + - During the installation process, you might need to modify some of + the installed files to suit the target layout. For example, you + might need to replace hard-coded paths in an initscript with + values of variables provided by the build system, such as + replacing ``/usr/bin/`` with ``${bindir}``. If you do perform such + modifications during :ref:`ref-tasks-install`, be sure to modify the + destination file after copying rather than before copying. + Modifying after copying ensures that the build system can + re-execute :ref:`ref-tasks-install` if needed. + + - ``oe_runmake install``, which can be run directly or can be run + indirectly by the :ref:`ref-classes-autotools` and + :ref:`ref-classes-cmake` classes, runs ``make install`` in parallel. + Sometimes, a Makefile can have missing dependencies between targets that + can result in race conditions. If you experience intermittent failures + during :ref:`ref-tasks-install`, you might be able to work around them by + disabling parallel Makefile installs by adding the following to the + recipe:: + + PARALLEL_MAKEINST = "" + + See :term:`PARALLEL_MAKEINST` for additional information. + + - If you need to install one or more custom CMake toolchain files + that are supplied by the application you are building, install the + files to ``${D}${datadir}/cmake/Modules`` during + :ref:`ref-tasks-install`. + +Enabling System Services +======================== + +If you want to install a service, which is a process that usually starts +on boot and runs in the background, then you must include some +additional definitions in your recipe. + +If you are adding services and the service initialization script or the +service file itself is not installed, you must provide for that +installation in your recipe using a ``do_install:append`` function. If +your recipe already has a :ref:`ref-tasks-install` function, update the function +near its end rather than adding an additional ``do_install:append`` +function. + +When you create the installation for your services, you need to +accomplish what is normally done by ``make install``. In other words, +make sure your installation arranges the output similar to how it is +arranged on the target system. + +The OpenEmbedded build system provides support for starting services two +different ways: + +- *SysVinit:* SysVinit is a system and service manager that manages the + init system used to control the very basic functions of your system. + The init program is the first program started by the Linux kernel + when the system boots. Init then controls the startup, running and + shutdown of all other programs. + + To enable a service using SysVinit, your recipe needs to inherit the + :ref:`ref-classes-update-rc.d` class. The class helps + facilitate safely installing the package on the target. + + You will need to set the + :term:`INITSCRIPT_PACKAGES`, + :term:`INITSCRIPT_NAME`, + and + :term:`INITSCRIPT_PARAMS` + variables within your recipe. + +- *systemd:* System Management Daemon (systemd) was designed to replace + SysVinit and to provide enhanced management of services. For more + information on systemd, see the systemd homepage at + https://freedesktop.org/wiki/Software/systemd/. + + To enable a service using systemd, your recipe needs to inherit the + :ref:`ref-classes-systemd` class. See the ``systemd.bbclass`` file + located in your :term:`Source Directory` section for more information. + +Packaging +========= + +Successful packaging is a combination of automated processes performed +by the OpenEmbedded build system and some specific steps you need to +take. The following list describes the process: + +- *Splitting Files*: The :ref:`ref-tasks-package` task splits the files produced + by the recipe into logical components. Even software that produces a + single binary might still have debug symbols, documentation, and + other logical components that should be split out. The :ref:`ref-tasks-package` + task ensures that files are split up and packaged correctly. + +- *Running QA Checks*: The :ref:`ref-classes-insane` class adds a + step to the package generation process so that output quality + assurance checks are generated by the OpenEmbedded build system. This + step performs a range of checks to be sure the build's output is free + of common problems that show up during runtime. For information on + these checks, see the :ref:`ref-classes-insane` class and + the ":ref:`ref-manual/qa-checks:qa error and warning messages`" + chapter in the Yocto Project Reference Manual. + +- *Hand-Checking Your Packages*: After you build your software, you + need to be sure your packages are correct. Examine the + ``${``\ :term:`WORKDIR`\ ``}/packages-split`` + directory and make sure files are where you expect them to be. If you + discover problems, you can set + :term:`PACKAGES`, + :term:`FILES`, + ``do_install(:append)``, and so forth as needed. + +- *Splitting an Application into Multiple Packages*: If you need to + split an application into several packages, see the + ":ref:`dev-manual/new-recipe:splitting an application into multiple packages`" + section for an example. + +- *Installing a Post-Installation Script*: For an example showing how + to install a post-installation script, see the + ":ref:`dev-manual/new-recipe:post-installation scripts`" section. + +- *Marking Package Architecture*: Depending on what your recipe is + building and how it is configured, it might be important to mark the + packages produced as being specific to a particular machine, or to + mark them as not being specific to a particular machine or + architecture at all. + + By default, packages apply to any machine with the same architecture + as the target machine. When a recipe produces packages that are + machine-specific (e.g. the + :term:`MACHINE` value is passed + into the configure script or a patch is applied only for a particular + machine), you should mark them as such by adding the following to the + recipe:: + + PACKAGE_ARCH = "${MACHINE_ARCH}" + + On the other hand, if the recipe produces packages that do not + contain anything specific to the target machine or architecture at + all (e.g. recipes that simply package script files or configuration + files), you should use the :ref:`ref-classes-allarch` class to + do this for you by adding this to your recipe:: + + inherit allarch + + Ensuring that the package architecture is correct is not critical + while you are doing the first few builds of your recipe. However, it + is important in order to ensure that your recipe rebuilds (or does + not rebuild) appropriately in response to changes in configuration, + and to ensure that you get the appropriate packages installed on the + target machine, particularly if you run separate builds for more than + one target machine. + +Sharing Files Between Recipes +============================= + +Recipes often need to use files provided by other recipes on the build +host. For example, an application linking to a common library needs +access to the library itself and its associated headers. The way this +access is accomplished is by populating a sysroot with files. Each +recipe has two sysroots in its work directory, one for target files +(``recipe-sysroot``) and one for files that are native to the build host +(``recipe-sysroot-native``). + +.. note:: + + You could find the term "staging" used within the Yocto project + regarding files populating sysroots (e.g. the :term:`STAGING_DIR` + variable). + +Recipes should never populate the sysroot directly (i.e. write files +into sysroot). Instead, files should be installed into standard +locations during the +:ref:`ref-tasks-install` task within +the ``${``\ :term:`D`\ ``}`` directory. The +reason for this limitation is that almost all files that populate the +sysroot are cataloged in manifests in order to ensure the files can be +removed later when a recipe is either modified or removed. Thus, the +sysroot is able to remain free from stale files. + +A subset of the files installed by the :ref:`ref-tasks-install` task are +used by the :ref:`ref-tasks-populate_sysroot` task as defined by the +:term:`SYSROOT_DIRS` variable to automatically populate the sysroot. It +is possible to modify the list of directories that populate the sysroot. +The following example shows how you could add the ``/opt`` directory to +the list of directories within a recipe:: + + SYSROOT_DIRS += "/opt" + +.. note:: + + The `/sysroot-only` is to be used by recipes that generate artifacts + that are not included in the target filesystem, allowing them to share + these artifacts without needing to use the :term:`DEPLOY_DIR`. + +For a more complete description of the :ref:`ref-tasks-populate_sysroot` +task and its associated functions, see the +:ref:`staging ` class. + +Using Virtual Providers +======================= + +Prior to a build, if you know that several different recipes provide the +same functionality, you can use a virtual provider (i.e. ``virtual/*``) +as a placeholder for the actual provider. The actual provider is +determined at build-time. + +A common scenario where a virtual provider is used would be for the kernel +recipe. Suppose you have three kernel recipes whose :term:`PN` values map to +``kernel-big``, ``kernel-mid``, and ``kernel-small``. Furthermore, each of +these recipes in some way uses a :term:`PROVIDES` statement that essentially +identifies itself as being able to provide ``virtual/kernel``. Here is one way +through the :ref:`ref-classes-kernel` class:: + + PROVIDES += "virtual/kernel" + +Any recipe that inherits the :ref:`ref-classes-kernel` class is +going to utilize a :term:`PROVIDES` statement that identifies that recipe as +being able to provide the ``virtual/kernel`` item. + +Now comes the time to actually build an image and you need a kernel +recipe, but which one? You can configure your build to call out the +kernel recipe you want by using the :term:`PREFERRED_PROVIDER` variable. As +an example, consider the :yocto_git:`x86-base.inc +` include file, which is a +machine (i.e. :term:`MACHINE`) configuration file. This include file is the +reason all x86-based machines use the ``linux-yocto`` kernel. Here are the +relevant lines from the include file:: + + PREFERRED_PROVIDER_virtual/kernel ??= "linux-yocto" + PREFERRED_VERSION_linux-yocto ??= "4.15%" + +When you use a virtual provider, you do not have to "hard code" a recipe +name as a build dependency. You can use the +:term:`DEPENDS` variable to state the +build is dependent on ``virtual/kernel`` for example:: + + DEPENDS = "virtual/kernel" + +During the build, the OpenEmbedded build system picks +the correct recipe needed for the ``virtual/kernel`` dependency based on +the :term:`PREFERRED_PROVIDER` variable. If you want to use the small kernel +mentioned at the beginning of this section, configure your build as +follows:: + + PREFERRED_PROVIDER_virtual/kernel ??= "kernel-small" + +.. note:: + + Any recipe that :term:`PROVIDES` a ``virtual/*`` item that is ultimately not + selected through :term:`PREFERRED_PROVIDER` does not get built. Preventing these + recipes from building is usually the desired behavior since this mechanism's + purpose is to select between mutually exclusive alternative providers. + +The following lists specific examples of virtual providers: + +- ``virtual/kernel``: Provides the name of the kernel recipe to use + when building a kernel image. + +- ``virtual/bootloader``: Provides the name of the bootloader to use + when building an image. + +- ``virtual/libgbm``: Provides ``gbm.pc``. + +- ``virtual/egl``: Provides ``egl.pc`` and possibly ``wayland-egl.pc``. + +- ``virtual/libgl``: Provides ``gl.pc`` (i.e. libGL). + +- ``virtual/libgles1``: Provides ``glesv1_cm.pc`` (i.e. libGLESv1_CM). + +- ``virtual/libgles2``: Provides ``glesv2.pc`` (i.e. libGLESv2). + +.. note:: + + Virtual providers only apply to build time dependencies specified with + :term:`PROVIDES` and :term:`DEPENDS`. They do not apply to runtime + dependencies specified with :term:`RPROVIDES` and :term:`RDEPENDS`. + +Properly Versioning Pre-Release Recipes +======================================= + +Sometimes the name of a recipe can lead to versioning problems when the +recipe is upgraded to a final release. For example, consider the +``irssi_0.8.16-rc1.bb`` recipe file in the list of example recipes in +the ":ref:`dev-manual/new-recipe:storing and naming the recipe`" section. +This recipe is at a release candidate stage (i.e. "rc1"). When the recipe is +released, the recipe filename becomes ``irssi_0.8.16.bb``. The version +change from ``0.8.16-rc1`` to ``0.8.16`` is seen as a decrease by the +build system and package managers, so the resulting packages will not +correctly trigger an upgrade. + +In order to ensure the versions compare properly, the recommended +convention is to set :term:`PV` within the +recipe to "previous_version+current_version". You can use an additional +variable so that you can use the current version elsewhere. Here is an +example:: + + REALPV = "0.8.16-rc1" + PV = "0.8.15+${REALPV}" + +Post-Installation Scripts +========================= + +Post-installation scripts run immediately after installing a package on +the target or during image creation when a package is included in an +image. To add a post-installation script to a package, add a +``pkg_postinst:``\ `PACKAGENAME`\ ``()`` function to the recipe file +(``.bb``) and replace `PACKAGENAME` with the name of the package you want +to attach to the ``postinst`` script. To apply the post-installation +script to the main package for the recipe, which is usually what is +required, specify +``${``\ :term:`PN`\ ``}`` in place of +PACKAGENAME. + +A post-installation function has the following structure:: + + pkg_postinst:PACKAGENAME() { + # Commands to carry out + } + +The script defined in the post-installation function is called when the +root filesystem is created. If the script succeeds, the package is +marked as installed. + +.. note:: + + Any RPM post-installation script that runs on the target should + return a 0 exit code. RPM does not allow non-zero exit codes for + these scripts, and the RPM package manager will cause the package to + fail installation on the target. + +Sometimes it is necessary for the execution of a post-installation +script to be delayed until the first boot. For example, the script might +need to be executed on the device itself. To delay script execution +until boot time, you must explicitly mark post installs to defer to the +target. You can use ``pkg_postinst_ontarget()`` or call +``postinst_intercept delay_to_first_boot`` from ``pkg_postinst()``. Any +failure of a ``pkg_postinst()`` script (including exit 1) triggers an +error during the +:ref:`ref-tasks-rootfs` task. + +If you have recipes that use ``pkg_postinst`` function and they require +the use of non-standard native tools that have dependencies during +root filesystem construction, you need to use the +:term:`PACKAGE_WRITE_DEPS` +variable in your recipe to list these tools. If you do not use this +variable, the tools might be missing and execution of the +post-installation script is deferred until first boot. Deferring the +script to the first boot is undesirable and impossible for read-only +root filesystems. + +.. note:: + + There is equivalent support for pre-install, pre-uninstall, and post-uninstall + scripts by way of ``pkg_preinst``, ``pkg_prerm``, and ``pkg_postrm``, + respectively. These scrips work in exactly the same way as does + ``pkg_postinst`` with the exception that they run at different times. Also, + because of when they run, they are not applicable to being run at image + creation time like ``pkg_postinst``. + +Testing +======= + +The final step for completing your recipe is to be sure that the +software you built runs correctly. To accomplish runtime testing, add +the build's output packages to your image and test them on the target. + +For information on how to customize your image by adding specific +packages, see ":ref:`dev-manual/customizing-images:customizing images`" section. + +Examples +======== + +To help summarize how to write a recipe, this section provides some +recipe examples given various scenarios: + +- `Building a single .c file package`_ + +- `Building a Makefile-based package`_ + +- `Building an Autotooled package`_ + +- `Building a Meson package`_ + +- `Splitting an application into multiple packages`_ + +- `Packaging externally produced binaries`_ + +Building a Single .c File Package +--------------------------------- + +Building an application from a single file that is stored locally (e.g. under +``files``) requires a recipe that has the file listed in the :term:`SRC_URI` +variable. Additionally, you need to manually write the :ref:`ref-tasks-compile` +and :ref:`ref-tasks-install` tasks. The :term:`S` variable defines the +directory containing the source code, which is set to :term:`WORKDIR` in this +case --- the directory BitBake uses for the build:: + + SUMMARY = "Simple helloworld application" + SECTION = "examples" + LICENSE = "MIT" + LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302" + + SRC_URI = "file://helloworld.c" + + S = "${WORKDIR}" + + do_compile() { + ${CC} ${LDFLAGS} helloworld.c -o helloworld + } + + do_install() { + install -d ${D}${bindir} + install -m 0755 helloworld ${D}${bindir} + } + +By default, the ``helloworld``, ``helloworld-dbg``, and ``helloworld-dev`` packages +are built. For information on how to customize the packaging process, see the +":ref:`dev-manual/new-recipe:splitting an application into multiple packages`" +section. + +Building a Makefile-Based Package +--------------------------------- + +Applications built with GNU ``make`` require a recipe that has the source archive +listed in :term:`SRC_URI`. You do not need to add a :ref:`ref-tasks-compile` +step since by default BitBake starts the ``make`` command to compile the +application. If you need additional ``make`` options, you should store them in +the :term:`EXTRA_OEMAKE` or :term:`PACKAGECONFIG_CONFARGS` variables. BitBake +passes these options into the GNU ``make`` invocation. Note that a +:ref:`ref-tasks-install` task is still required. Otherwise, BitBake runs an +empty :ref:`ref-tasks-install` task by default. + +Some applications might require extra parameters to be passed to the +compiler. For example, the application might need an additional header +path. You can accomplish this by adding to the :term:`CFLAGS` variable. The +following example shows this:: + + CFLAGS:prepend = "-I ${S}/include " + +In the following example, ``lz4`` is a makefile-based package:: + + SUMMARY = "Extremely Fast Compression algorithm" + DESCRIPTION = "LZ4 is a very fast lossless compression algorithm, providing compression speed at 400 MB/s per core, scalable with multi-cores CPU. It also features an extremely fast decoder, with speed in multiple GB/s per core, typically reaching RAM speed limits on multi-core systems." + HOMEPAGE = "https://github.com/lz4/lz4" + + LICENSE = "BSD-2-Clause | GPL-2.0-only" + LIC_FILES_CHKSUM = "file://lib/LICENSE;md5=ebc2ea4814a64de7708f1571904b32cc \ + file://programs/COPYING;md5=b234ee4d69f5fce4486a80fdaf4a4263 \ + file://LICENSE;md5=d57c0d21cb917fb4e0af2454aa48b956 \ + " + + PE = "1" + + SRCREV = "d44371841a2f1728a3f36839fd4b7e872d0927d3" + + SRC_URI = "git://github.com/lz4/lz4.git;branch=release;protocol=https \ + file://CVE-2021-3520.patch \ + " + UPSTREAM_CHECK_GITTAGREGEX = "v(?P.*)" + + S = "${WORKDIR}/git" + + # Fixed in r118, which is larger than the current version. + CVE_CHECK_IGNORE += "CVE-2014-4715" + + EXTRA_OEMAKE = "PREFIX=${prefix} CC='${CC}' CFLAGS='${CFLAGS}' DESTDIR=${D} LIBDIR=${libdir} INCLUDEDIR=${includedir} BUILD_STATIC=no" + + do_install() { + oe_runmake install + } + + BBCLASSEXTEND = "native nativesdk" + +Building an Autotooled Package +------------------------------ + +Applications built with the Autotools such as ``autoconf`` and ``automake`` +require a recipe that has a source archive listed in :term:`SRC_URI` and also +inherit the :ref:`ref-classes-autotools` class, which contains the definitions +of all the steps needed to build an Autotool-based application. The result of +the build is automatically packaged. And, if the application uses NLS for +localization, packages with local information are generated (one package per +language). Following is one example: (``hello_2.3.bb``):: + + SUMMARY = "GNU Helloworld application" + SECTION = "examples" + LICENSE = "GPL-2.0-or-later" + LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe" + + SRC_URI = "${GNU_MIRROR}/hello/hello-${PV}.tar.gz" + + inherit autotools gettext + +The variable :term:`LIC_FILES_CHKSUM` is used to track source license changes +as described in the ":ref:`dev-manual/licenses:tracking license changes`" +section in the Yocto Project Overview and Concepts Manual. You can quickly +create Autotool-based recipes in a manner similar to the previous example. + +.. _ref-building-meson-package: + +Building a Meson Package +------------------------ + +Applications built with the `Meson build system `__ +just need a recipe that has sources described in :term:`SRC_URI` and inherits +the :ref:`ref-classes-meson` class. + +The :oe_git:`ipcalc recipe ` +is a simple example of an application without dependencies:: + + SUMMARY = "Tool to assist in network address calculations for IPv4 and IPv6." + HOMEPAGE = "https://gitlab.com/ipcalc/ipcalc" + + SECTION = "net" + + LICENSE = "GPL-2.0-only" + LIC_FILES_CHKSUM = "file://COPYING;md5=b234ee4d69f5fce4486a80fdaf4a4263" + + SRC_URI = "git://gitlab.com/ipcalc/ipcalc.git;protocol=https;branch=master" + SRCREV = "4c4261a47f355946ee74013d4f5d0494487cc2d6" + + S = "${WORKDIR}/git" + + inherit meson + +Applications with dependencies are likely to inherit the +:ref:`ref-classes-pkgconfig` class, as ``pkg-config`` is the default method +used by Meson to find dependencies and compile applications against them. + +Splitting an Application into Multiple Packages +----------------------------------------------- + +You can use the variables :term:`PACKAGES` and :term:`FILES` to split an +application into multiple packages. + +Following is an example that uses the ``libxpm`` recipe. By default, +this recipe generates a single package that contains the library along +with a few binaries. You can modify the recipe to split the binaries +into separate packages:: + + require xorg-lib-common.inc + + SUMMARY = "Xpm: X Pixmap extension library" + LICENSE = "MIT" + LIC_FILES_CHKSUM = "file://COPYING;md5=51f4270b012ecd4ab1a164f5f4ed6cf7" + DEPENDS += "libxext libsm libxt" + PE = "1" + + XORG_PN = "libXpm" + + PACKAGES =+ "sxpm cxpm" + FILES:cxpm = "${bindir}/cxpm" + FILES:sxpm = "${bindir}/sxpm" + +In the previous example, we want to ship the ``sxpm`` and ``cxpm`` +binaries in separate packages. Since ``bindir`` would be packaged into +the main :term:`PN` package by default, we prepend the :term:`PACKAGES` variable +so additional package names are added to the start of list. This results +in the extra ``FILES:*`` variables then containing information that +define which files and directories go into which packages. Files +included by earlier packages are skipped by latter packages. Thus, the +main :term:`PN` package does not include the above listed files. + +Packaging Externally Produced Binaries +-------------------------------------- + +Sometimes, you need to add pre-compiled binaries to an image. For +example, suppose that there are binaries for proprietary code, +created by a particular division of a company. Your part of the company +needs to use those binaries as part of an image that you are building +using the OpenEmbedded build system. Since you only have the binaries +and not the source code, you cannot use a typical recipe that expects to +fetch the source specified in +:term:`SRC_URI` and then compile it. + +One method is to package the binaries and then install them as part of +the image. Generally, it is not a good idea to package binaries since, +among other things, it can hinder the ability to reproduce builds and +could lead to compatibility problems with ABI in the future. However, +sometimes you have no choice. + +The easiest solution is to create a recipe that uses the +:ref:`ref-classes-bin-package` class and to be sure that you are using default +locations for build artifacts. In most cases, the +:ref:`ref-classes-bin-package` class handles "skipping" the configure and +compile steps as well as sets things up to grab packages from the appropriate +area. In particular, this class sets ``noexec`` on both the +:ref:`ref-tasks-configure` and :ref:`ref-tasks-compile` tasks, sets +``FILES:${PN}`` to "/" so that it picks up all files, and sets up a +:ref:`ref-tasks-install` task, which effectively copies all files from ``${S}`` +to ``${D}``. The :ref:`ref-classes-bin-package` class works well when the files +extracted into ``${S}`` are already laid out in the way they should be laid out +on the target. For more information on these variables, see the :term:`FILES`, +:term:`PN`, :term:`S`, and :term:`D` variables in the Yocto Project Reference +Manual's variable glossary. + +.. note:: + + - Using :term:`DEPENDS` is a good + idea even for components distributed in binary form, and is often + necessary for shared libraries. For a shared library, listing the + library dependencies in :term:`DEPENDS` makes sure that the libraries + are available in the staging sysroot when other recipes link + against the library, which might be necessary for successful + linking. + + - Using :term:`DEPENDS` also allows runtime dependencies between + packages to be added automatically. See the + ":ref:`overview-manual/concepts:automatically added runtime dependencies`" + section in the Yocto Project Overview and Concepts Manual for more + information. + +If you cannot use the :ref:`ref-classes-bin-package` class, you need to be sure you are +doing the following: + +- Create a recipe where the + :ref:`ref-tasks-configure` and + :ref:`ref-tasks-compile` tasks do + nothing: It is usually sufficient to just not define these tasks in + the recipe, because the default implementations do nothing unless a + Makefile is found in + ``${``\ :term:`S`\ ``}``. + + If ``${S}`` might contain a Makefile, or if you inherit some class + that replaces :ref:`ref-tasks-configure` and :ref:`ref-tasks-compile` with custom + versions, then you can use the + ``[``\ :ref:`noexec `\ ``]`` + flag to turn the tasks into no-ops, as follows:: + + do_configure[noexec] = "1" + do_compile[noexec] = "1" + + Unlike :ref:`bitbake-user-manual/bitbake-user-manual-metadata:deleting a task`, + using the flag preserves the dependency chain from the :ref:`ref-tasks-fetch`, + :ref:`ref-tasks-unpack`, and :ref:`ref-tasks-patch` tasks to the + :ref:`ref-tasks-install` task. + +- Make sure your :ref:`ref-tasks-install` task installs the binaries + appropriately. + +- Ensure that you set up :term:`FILES` + (usually + ``FILES:${``\ :term:`PN`\ ``}``) to + point to the files you have installed, which of course depends on + where you have installed them and whether those files are in + different locations than the defaults. + +Following Recipe Style Guidelines +================================= + +When writing recipes, it is good to conform to existing style +guidelines. The :oe_wiki:`OpenEmbedded Styleguide ` wiki page +provides rough guidelines for preferred recipe style. + +It is common for existing recipes to deviate a bit from this style. +However, aiming for at least a consistent style is a good idea. Some +practices, such as omitting spaces around ``=`` operators in assignments +or ordering recipe components in an erratic way, are widely seen as poor +style. + +Recipe Syntax +============= + +Understanding recipe file syntax is important for writing recipes. The +following list overviews the basic items that make up a BitBake recipe +file. For more complete BitBake syntax descriptions, see the +":doc:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata`" +chapter of the BitBake User Manual. + +- *Variable Assignments and Manipulations:* Variable assignments allow + a value to be assigned to a variable. The assignment can be static + text or might include the contents of other variables. In addition to + the assignment, appending and prepending operations are also + supported. + + The following example shows some of the ways you can use variables in + recipes:: + + S = "${WORKDIR}/postfix-${PV}" + CFLAGS += "-DNO_ASM" + CFLAGS:append = " --enable-important-feature" + +- *Functions:* Functions provide a series of actions to be performed. + You usually use functions to override the default implementation of a + task function or to complement a default function (i.e. append or + prepend to an existing function). Standard functions use ``sh`` shell + syntax, although access to OpenEmbedded variables and internal + methods are also available. + + Here is an example function from the ``sed`` recipe:: + + do_install () { + autotools_do_install + install -d ${D}${base_bindir} + mv ${D}${bindir}/sed ${D}${base_bindir}/sed + rmdir ${D}${bindir}/ + } + + It is + also possible to implement new functions that are called between + existing tasks as long as the new functions are not replacing or + complementing the default functions. You can implement functions in + Python instead of shell. Both of these options are not seen in the + majority of recipes. + +- *Keywords:* BitBake recipes use only a few keywords. You use keywords + to include common functions (``inherit``), load parts of a recipe + from other files (``include`` and ``require``) and export variables + to the environment (``export``). + + The following example shows the use of some of these keywords:: + + export POSTCONF = "${STAGING_BINDIR}/postconf" + inherit autoconf + require otherfile.inc + +- *Comments (#):* Any lines that begin with the hash character (``#``) + are treated as comment lines and are ignored:: + + # This is a comment + +This next list summarizes the most important and most commonly used +parts of the recipe syntax. For more information on these parts of the +syntax, you can reference the +":doc:`bitbake:bitbake-user-manual/bitbake-user-manual-metadata`" chapter +in the BitBake User Manual. + +- *Line Continuation (\\):* Use the backward slash (``\``) character to + split a statement over multiple lines. Place the slash character at + the end of the line that is to be continued on the next line:: + + VAR = "A really long \ + line" + + .. note:: + + You cannot have any characters including spaces or tabs after the + slash character. + +- *Using Variables (${VARNAME}):* Use the ``${VARNAME}`` syntax to + access the contents of a variable:: + + SRC_URI = "${SOURCEFORGE_MIRROR}/libpng/zlib-${PV}.tar.gz" + + .. note:: + + It is important to understand that the value of a variable + expressed in this form does not get substituted automatically. The + expansion of these expressions happens on-demand later (e.g. + usually when a function that makes reference to the variable + executes). This behavior ensures that the values are most + appropriate for the context in which they are finally used. On the + rare occasion that you do need the variable expression to be + expanded immediately, you can use the + := + operator instead of + = + when you make the assignment, but this is not generally needed. + +- *Quote All Assignments ("value"):* Use double quotes around values in + all variable assignments (e.g. ``"value"``). Following is an example:: + + VAR1 = "${OTHERVAR}" + VAR2 = "The version is ${PV}" + +- *Conditional Assignment (?=):* Conditional assignment is used to + assign a value to a variable, but only when the variable is currently + unset. Use the question mark followed by the equal sign (``?=``) to + make a "soft" assignment used for conditional assignment. Typically, + "soft" assignments are used in the ``local.conf`` file for variables + that are allowed to come through from the external environment. + + Here is an example where ``VAR1`` is set to "New value" if it is + currently empty. However, if ``VAR1`` has already been set, it + remains unchanged:: + + VAR1 ?= "New value" + + In this next example, ``VAR1`` is left with the value "Original value":: + + VAR1 = "Original value" + VAR1 ?= "New value" + +- *Appending (+=):* Use the plus character followed by the equals sign + (``+=``) to append values to existing variables. + + .. note:: + + This operator adds a space between the existing content of the + variable and the new content. + + Here is an example:: + + SRC_URI += "file://fix-makefile.patch" + +- *Prepending (=+):* Use the equals sign followed by the plus character + (``=+``) to prepend values to existing variables. + + .. note:: + + This operator adds a space between the new content and the + existing content of the variable. + + Here is an example:: + + VAR =+ "Starts" + +- *Appending (:append):* Use the ``:append`` operator to append values + to existing variables. This operator does not add any additional + space. Also, the operator is applied after all the ``+=``, and ``=+`` + operators have been applied and after all ``=`` assignments have + occurred. This means that if ``:append`` is used in a recipe, it can + only be overridden by another layer using the special ``:remove`` + operator, which in turn will prevent further layers from adding it back. + + The following example shows the space being explicitly added to the + start to ensure the appended value is not merged with the existing + value:: + + CFLAGS:append = " --enable-important-feature" + + You can also use + the ``:append`` operator with overrides, which results in the actions + only being performed for the specified target or machine:: + + CFLAGS:append:sh4 = " --enable-important-sh4-specific-feature" + +- *Prepending (:prepend):* Use the ``:prepend`` operator to prepend + values to existing variables. This operator does not add any + additional space. Also, the operator is applied after all the ``+=``, + and ``=+`` operators have been applied and after all ``=`` + assignments have occurred. + + The following example shows the space being explicitly added to the + end to ensure the prepended value is not merged with the existing + value:: + + CFLAGS:prepend = "-I${S}/myincludes " + + You can also use the + ``:prepend`` operator with overrides, which results in the actions + only being performed for the specified target or machine:: + + CFLAGS:prepend:sh4 = "-I${S}/myincludes " + +- *Overrides:* You can use overrides to set a value conditionally, + typically based on how the recipe is being built. For example, to set + the :term:`KBRANCH` variable's + value to "standard/base" for any target + :term:`MACHINE`, except for + qemuarm where it should be set to "standard/arm-versatile-926ejs", + you would do the following:: + + KBRANCH = "standard/base" + KBRANCH:qemuarm = "standard/arm-versatile-926ejs" + + Overrides are also used to separate + alternate values of a variable in other situations. For example, when + setting variables such as + :term:`FILES` and + :term:`RDEPENDS` that are + specific to individual packages produced by a recipe, you should + always use an override that specifies the name of the package. + +- *Indentation:* Use spaces for indentation rather than tabs. For + shell functions, both currently work. However, it is a policy + decision of the Yocto Project to use tabs in shell functions. Realize + that some layers have a policy to use spaces for all indentation. + +- *Using Python for Complex Operations:* For more advanced processing, + it is possible to use Python code during variable assignments (e.g. + search and replacement on a variable). + + You indicate Python code using the ``${@python_code}`` syntax for the + variable assignment:: + + SRC_URI = "ftp://ftp.info-zip.org/pub/infozip/src/zip${@d.getVar('PV',1).replace('.', '')}.tgz + +- *Shell Function Syntax:* Write shell functions as if you were writing + a shell script when you describe a list of actions to take. You + should ensure that your script works with a generic ``sh`` and that + it does not require any ``bash`` or other shell-specific + functionality. The same considerations apply to various system + utilities (e.g. ``sed``, ``grep``, ``awk``, and so forth) that you + might wish to use. If in doubt, you should check with multiple + implementations --- including those from BusyBox. + diff --git a/documentation/dev-manual/packages.rst b/documentation/dev-manual/packages.rst new file mode 100644 index 0000000000..79f21d9f34 --- /dev/null +++ b/documentation/dev-manual/packages.rst @@ -0,0 +1,1238 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Working with Packages +********************* + +This section describes a few tasks that involve packages: + +- :ref:`dev-manual/packages:excluding packages from an image` + +- :ref:`dev-manual/packages:incrementing a package version` + +- :ref:`dev-manual/packages:handling optional module packaging` + +- :ref:`dev-manual/packages:using runtime package management` + +- :ref:`dev-manual/packages:generating and using signed packages` + +- :ref:`Setting up and running package test + (ptest) ` + +- :ref:`dev-manual/packages:creating node package manager (npm) packages` + +- :ref:`dev-manual/packages:adding custom metadata to packages` + +Excluding Packages from an Image +================================ + +You might find it necessary to prevent specific packages from being +installed into an image. If so, you can use several variables to direct +the build system to essentially ignore installing recommended packages +or to not install a package at all. + +The following list introduces variables you can use to prevent packages +from being installed into your image. Each of these variables only works +with IPK and RPM package types, not for Debian packages. +Also, you can use these variables from your ``local.conf`` file +or attach them to a specific image recipe by using a recipe name +override. For more detail on the variables, see the descriptions in the +Yocto Project Reference Manual's glossary chapter. + +- :term:`BAD_RECOMMENDATIONS`: + Use this variable to specify "recommended-only" packages that you do + not want installed. + +- :term:`NO_RECOMMENDATIONS`: + Use this variable to prevent all "recommended-only" packages from + being installed. + +- :term:`PACKAGE_EXCLUDE`: + Use this variable to prevent specific packages from being installed + regardless of whether they are "recommended-only" or not. You need to + realize that the build process could fail with an error when you + prevent the installation of a package whose presence is required by + an installed package. + +Incrementing a Package Version +============================== + +This section provides some background on how binary package versioning +is accomplished and presents some of the services, variables, and +terminology involved. + +In order to understand binary package versioning, you need to consider +the following: + +- Binary Package: The binary package that is eventually built and + installed into an image. + +- Binary Package Version: The binary package version is composed of two + components --- a version and a revision. + + .. note:: + + Technically, a third component, the "epoch" (i.e. :term:`PE`) is involved + but this discussion for the most part ignores :term:`PE`. + + The version and revision are taken from the + :term:`PV` and + :term:`PR` variables, respectively. + +- :term:`PV`: The recipe version. :term:`PV` represents the version of the + software being packaged. Do not confuse :term:`PV` with the binary + package version. + +- :term:`PR`: The recipe revision. + +- :term:`SRCPV`: The OpenEmbedded + build system uses this string to help define the value of :term:`PV` when + the source code revision needs to be included in it. + +- :yocto_wiki:`PR Service `: A + network-based service that helps automate keeping package feeds + compatible with existing package manager applications such as RPM, + APT, and OPKG. + +Whenever the binary package content changes, the binary package version +must change. Changing the binary package version is accomplished by +changing or "bumping" the :term:`PR` and/or :term:`PV` values. Increasing these +values occurs one of two ways: + +- Automatically using a Package Revision Service (PR Service). + +- Manually incrementing the :term:`PR` and/or :term:`PV` variables. + +Given a primary challenge of any build system and its users is how to +maintain a package feed that is compatible with existing package manager +applications such as RPM, APT, and OPKG, using an automated system is +much preferred over a manual system. In either system, the main +requirement is that binary package version numbering increases in a +linear fashion and that there is a number of version components that +support that linear progression. For information on how to ensure +package revisioning remains linear, see the +":ref:`dev-manual/packages:automatically incrementing a package version number`" +section. + +The following three sections provide related information on the PR +Service, the manual method for "bumping" :term:`PR` and/or :term:`PV`, and on +how to ensure binary package revisioning remains linear. + +Working With a PR Service +------------------------- + +As mentioned, attempting to maintain revision numbers in the +:term:`Metadata` is error prone, inaccurate, +and causes problems for people submitting recipes. Conversely, the PR +Service automatically generates increasing numbers, particularly the +revision field, which removes the human element. + +.. note:: + + For additional information on using a PR Service, you can see the + :yocto_wiki:`PR Service ` wiki page. + +The Yocto Project uses variables in order of decreasing priority to +facilitate revision numbering (i.e. +:term:`PE`, +:term:`PV`, and +:term:`PR` for epoch, version, and +revision, respectively). The values are highly dependent on the policies +and procedures of a given distribution and package feed. + +Because the OpenEmbedded build system uses +":ref:`signatures `", which are +unique to a given build, the build system knows when to rebuild +packages. All the inputs into a given task are represented by a +signature, which can trigger a rebuild when different. Thus, the build +system itself does not rely on the :term:`PR`, :term:`PV`, and :term:`PE` numbers to +trigger a rebuild. The signatures, however, can be used to generate +these values. + +The PR Service works with both ``OEBasic`` and ``OEBasicHash`` +generators. The value of :term:`PR` bumps when the checksum changes and the +different generator mechanisms change signatures under different +circumstances. + +As implemented, the build system includes values from the PR Service +into the :term:`PR` field as an addition using the form "``.x``" so ``r0`` +becomes ``r0.1``, ``r0.2`` and so forth. This scheme allows existing +:term:`PR` values to be used for whatever reasons, which include manual +:term:`PR` bumps, should it be necessary. + +By default, the PR Service is not enabled or running. Thus, the packages +generated are just "self consistent". The build system adds and removes +packages and there are no guarantees about upgrade paths but images will +be consistent and correct with the latest changes. + +The simplest form for a PR Service is for a single host development system +that builds the package feed (building system). For this scenario, you can +enable a local PR Service by setting :term:`PRSERV_HOST` in your +``local.conf`` file in the :term:`Build Directory`:: + + PRSERV_HOST = "localhost:0" + +Once the service is started, packages will automatically +get increasing :term:`PR` values and BitBake takes care of starting and +stopping the server. + +If you have a more complex setup where multiple host development systems +work against a common, shared package feed, you have a single PR Service +running and it is connected to each building system. For this scenario, +you need to start the PR Service using the ``bitbake-prserv`` command:: + + bitbake-prserv --host ip --port port --start + +In addition to +hand-starting the service, you need to update the ``local.conf`` file of +each building system as described earlier so each system points to the +server and port. + +It is also recommended you use build history, which adds some sanity +checks to binary package versions, in conjunction with the server that +is running the PR Service. To enable build history, add the following to +each building system's ``local.conf`` file:: + + # It is recommended to activate "buildhistory" for testing the PR service + INHERIT += "buildhistory" + BUILDHISTORY_COMMIT = "1" + +For information on build +history, see the +":ref:`dev-manual/build-quality:maintaining build output quality`" section. + +.. note:: + + The OpenEmbedded build system does not maintain :term:`PR` information as + part of the shared state (sstate) packages. If you maintain an sstate + feed, it's expected that either all your building systems that + contribute to the sstate feed use a shared PR Service, or you do not + run a PR Service on any of your building systems. Having some systems + use a PR Service while others do not leads to obvious problems. + + For more information on shared state, see the + ":ref:`overview-manual/concepts:shared state cache`" + section in the Yocto Project Overview and Concepts Manual. + +Manually Bumping PR +------------------- + +The alternative to setting up a PR Service is to manually "bump" the +:term:`PR` variable. + +If a committed change results in changing the package output, then the +value of the :term:`PR` variable needs to be increased (or "bumped") as part of +that commit. For new recipes you should add the :term:`PR` variable and set +its initial value equal to "r0", which is the default. Even though the +default value is "r0", the practice of adding it to a new recipe makes +it harder to forget to bump the variable when you make changes to the +recipe in future. + +Usually, version increases occur only to binary packages. However, if +for some reason :term:`PV` changes but does not increase, you can increase +the :term:`PE` variable (Package Epoch). The :term:`PE` variable defaults to +"0". + +Binary package version numbering strives to follow the `Debian Version +Field Policy +Guidelines `__. +These guidelines define how versions are compared and what "increasing" +a version means. + +Automatically Incrementing a Package Version Number +--------------------------------------------------- + +When fetching a repository, BitBake uses the +:term:`SRCREV` variable to determine +the specific source code revision from which to build. You set the +:term:`SRCREV` variable to +:term:`AUTOREV` to cause the +OpenEmbedded build system to automatically use the latest revision of +the software:: + + SRCREV = "${AUTOREV}" + +Furthermore, you need to reference :term:`SRCPV` in :term:`PV` in order to +automatically update the version whenever the revision of the source +code changes. Here is an example:: + + PV = "1.0+git${SRCPV}" + +The OpenEmbedded build system substitutes :term:`SRCPV` with the following: + +.. code-block:: none + + AUTOINC+source_code_revision + +The build system replaces the ``AUTOINC`` +with a number. The number used depends on the state of the PR Service: + +- If PR Service is enabled, the build system increments the number, + which is similar to the behavior of + :term:`PR`. This behavior results in + linearly increasing package versions, which is desirable. Here is an + example: + + .. code-block:: none + + hello-world-git_0.0+git0+b6558dd387-r0.0_armv7a-neon.ipk + hello-world-git_0.0+git1+dd2f5c3565-r0.0_armv7a-neon.ipk + +- If PR Service is not enabled, the build system replaces the + ``AUTOINC`` placeholder with zero (i.e. "0"). This results in + changing the package version since the source revision is included. + However, package versions are not increased linearly. Here is an + example: + + .. code-block:: none + + hello-world-git_0.0+git0+b6558dd387-r0.0_armv7a-neon.ipk + hello-world-git_0.0+git0+dd2f5c3565-r0.0_armv7a-neon.ipk + +In summary, the OpenEmbedded build system does not track the history of +binary package versions for this purpose. ``AUTOINC``, in this case, is +comparable to :term:`PR`. If PR server is not enabled, ``AUTOINC`` in the +package version is simply replaced by "0". If PR server is enabled, the +build system keeps track of the package versions and bumps the number +when the package revision changes. + +Handling Optional Module Packaging +================================== + +Many pieces of software split functionality into optional modules (or +plugins) and the plugins that are built might depend on configuration +options. To avoid having to duplicate the logic that determines what +modules are available in your recipe or to avoid having to package each +module by hand, the OpenEmbedded build system provides functionality to +handle module packaging dynamically. + +To handle optional module packaging, you need to do two things: + +- Ensure the module packaging is actually done. + +- Ensure that any dependencies on optional modules from other recipes + are satisfied by your recipe. + +Making Sure the Packaging is Done +--------------------------------- + +To ensure the module packaging actually gets done, you use the +``do_split_packages`` function within the ``populate_packages`` Python +function in your recipe. The ``do_split_packages`` function searches for +a pattern of files or directories under a specified path and creates a +package for each one it finds by appending to the +:term:`PACKAGES` variable and +setting the appropriate values for ``FILES:packagename``, +``RDEPENDS:packagename``, ``DESCRIPTION:packagename``, and so forth. +Here is an example from the ``lighttpd`` recipe:: + + python populate_packages:prepend () { + lighttpd_libdir = d.expand('${libdir}') + do_split_packages(d, lighttpd_libdir, '^mod_(.*).so$', + 'lighttpd-module-%s', 'Lighttpd module for %s', + extra_depends='') + } + +The previous example specifies a number of things in the call to +``do_split_packages``. + +- A directory within the files installed by your recipe through + :ref:`ref-tasks-install` in which to search. + +- A regular expression used to match module files in that directory. In + the example, note the parentheses () that mark the part of the + expression from which the module name should be derived. + +- A pattern to use for the package names. + +- A description for each package. + +- An empty string for ``extra_depends``, which disables the default + dependency on the main ``lighttpd`` package. Thus, if a file in + ``${libdir}`` called ``mod_alias.so`` is found, a package called + ``lighttpd-module-alias`` is created for it and the + :term:`DESCRIPTION` is set to + "Lighttpd module for alias". + +Often, packaging modules is as simple as the previous example. However, +there are more advanced options that you can use within +``do_split_packages`` to modify its behavior. And, if you need to, you +can add more logic by specifying a hook function that is called for each +package. It is also perfectly acceptable to call ``do_split_packages`` +multiple times if you have more than one set of modules to package. + +For more examples that show how to use ``do_split_packages``, see the +``connman.inc`` file in the ``meta/recipes-connectivity/connman/`` +directory of the ``poky`` :ref:`source repository `. You can +also find examples in ``meta/classes-recipe/kernel.bbclass``. + +Following is a reference that shows ``do_split_packages`` mandatory and +optional arguments:: + + Mandatory arguments + + root + The path in which to search + file_regex + Regular expression to match searched files. + Use parentheses () to mark the part of this + expression that should be used to derive the + module name (to be substituted where %s is + used in other function arguments as noted below) + output_pattern + Pattern to use for the package names. Must + include %s. + description + Description to set for each package. Must + include %s. + + Optional arguments + + postinst + Postinstall script to use for all packages + (as a string) + recursive + True to perform a recursive search --- default + False + hook + A hook function to be called for every match. + The function will be called with the following + arguments (in the order listed): + + f + Full path to the file/directory match + pkg + The package name + file_regex + As above + output_pattern + As above + modulename + The module name derived using file_regex + extra_depends + Extra runtime dependencies (RDEPENDS) to be + set for all packages. The default value of None + causes a dependency on the main package + (${PN}) --- if you do not want this, pass empty + string '' for this parameter. + aux_files_pattern + Extra item(s) to be added to FILES for each + package. Can be a single string item or a list + of strings for multiple items. Must include %s. + postrm + postrm script to use for all packages (as a + string) + allow_dirs + True to allow directories to be matched - + default False + prepend + If True, prepend created packages to PACKAGES + instead of the default False which appends them + match_path + match file_regex on the whole relative path to + the root rather than just the filename + aux_files_pattern_verbatim + Extra item(s) to be added to FILES for each + package, using the actual derived module name + rather than converting it to something legal + for a package name. Can be a single string item + or a list of strings for multiple items. Must + include %s. + allow_links + True to allow symlinks to be matched --- default + False + summary + Summary to set for each package. Must include %s; + defaults to description if not set. + + + +Satisfying Dependencies +----------------------- + +The second part for handling optional module packaging is to ensure that +any dependencies on optional modules from other recipes are satisfied by +your recipe. You can be sure these dependencies are satisfied by using +the :term:`PACKAGES_DYNAMIC` +variable. Here is an example that continues with the ``lighttpd`` recipe +shown earlier:: + + PACKAGES_DYNAMIC = "lighttpd-module-.*" + +The name +specified in the regular expression can of course be anything. In this +example, it is ``lighttpd-module-`` and is specified as the prefix to +ensure that any :term:`RDEPENDS` and +:term:`RRECOMMENDS` on a package +name starting with the prefix are satisfied during build time. If you +are using ``do_split_packages`` as described in the previous section, +the value you put in :term:`PACKAGES_DYNAMIC` should correspond to the name +pattern specified in the call to ``do_split_packages``. + +Using Runtime Package Management +================================ + +During a build, BitBake always transforms a recipe into one or more +packages. For example, BitBake takes the ``bash`` recipe and produces a +number of packages (e.g. ``bash``, ``bash-bashbug``, +``bash-completion``, ``bash-completion-dbg``, ``bash-completion-dev``, +``bash-completion-extra``, ``bash-dbg``, and so forth). Not all +generated packages are included in an image. + +In several situations, you might need to update, add, remove, or query +the packages on a target device at runtime (i.e. without having to +generate a new image). Examples of such situations include: + +- You want to provide in-the-field updates to deployed devices (e.g. + security updates). + +- You want to have a fast turn-around development cycle for one or more + applications that run on your device. + +- You want to temporarily install the "debug" packages of various + applications on your device so that debugging can be greatly improved + by allowing access to symbols and source debugging. + +- You want to deploy a more minimal package selection of your device + but allow in-the-field updates to add a larger selection for + customization. + +In all these situations, you have something similar to a more +traditional Linux distribution in that in-field devices are able to +receive pre-compiled packages from a server for installation or update. +Being able to install these packages on a running, in-field device is +what is termed "runtime package management". + +In order to use runtime package management, you need a host or server +machine that serves up the pre-compiled packages plus the required +metadata. You also need package manipulation tools on the target. The +build machine is a likely candidate to act as the server. However, that +machine does not necessarily have to be the package server. The build +machine could push its artifacts to another machine that acts as the +server (e.g. Internet-facing). In fact, doing so is advantageous for a +production environment as getting the packages away from the development +system's :term:`Build Directory` prevents accidental overwrites. + +A simple build that targets just one device produces more than one +package database. In other words, the packages produced by a build are +separated out into a couple of different package groupings based on +criteria such as the target's CPU architecture, the target board, or the +C library used on the target. For example, a build targeting the +``qemux86`` device produces the following three package databases: +``noarch``, ``i586``, and ``qemux86``. If you wanted your ``qemux86`` +device to be aware of all the packages that were available to it, you +would need to point it to each of these databases individually. In a +similar way, a traditional Linux distribution usually is configured to +be aware of a number of software repositories from which it retrieves +packages. + +Using runtime package management is completely optional and not required +for a successful build or deployment in any way. But if you want to make +use of runtime package management, you need to do a couple things above +and beyond the basics. The remainder of this section describes what you +need to do. + +Build Considerations +-------------------- + +This section describes build considerations of which you need to be +aware in order to provide support for runtime package management. + +When BitBake generates packages, it needs to know what format or formats +to use. In your configuration, you use the +:term:`PACKAGE_CLASSES` +variable to specify the format: + +#. Open the ``local.conf`` file inside your :term:`Build Directory` (e.g. + ``poky/build/conf/local.conf``). + +#. Select the desired package format as follows:: + + PACKAGE_CLASSES ?= "package_packageformat" + + where packageformat can be "ipk", "rpm", + "deb", or "tar" which are the supported package formats. + + .. note:: + + Because the Yocto Project supports four different package formats, + you can set the variable with more than one argument. However, the + OpenEmbedded build system only uses the first argument when + creating an image or Software Development Kit (SDK). + +If you would like your image to start off with a basic package database +containing the packages in your current build as well as to have the +relevant tools available on the target for runtime package management, +you can include "package-management" in the +:term:`IMAGE_FEATURES` +variable. Including "package-management" in this configuration variable +ensures that when the image is assembled for your target, the image +includes the currently-known package databases as well as the +target-specific tools required for runtime package management to be +performed on the target. However, this is not strictly necessary. You +could start your image off without any databases but only include the +required on-target package tool(s). As an example, you could include +"opkg" in your +:term:`IMAGE_INSTALL` variable +if you are using the IPK package format. You can then initialize your +target's package database(s) later once your image is up and running. + +Whenever you perform any sort of build step that can potentially +generate a package or modify existing package, it is always a good idea +to re-generate the package index after the build by using the following +command:: + + $ bitbake package-index + +It might be tempting to build the +package and the package index at the same time with a command such as +the following:: + + $ bitbake some-package package-index + +Do not do this as +BitBake does not schedule the package index for after the completion of +the package you are building. Consequently, you cannot be sure of the +package index including information for the package you just built. +Thus, be sure to run the package update step separately after building +any packages. + +You can use the +:term:`PACKAGE_FEED_ARCHS`, +:term:`PACKAGE_FEED_BASE_PATHS`, +and +:term:`PACKAGE_FEED_URIS` +variables to pre-configure target images to use a package feed. If you +do not define these variables, then manual steps as described in the +subsequent sections are necessary to configure the target. You should +set these variables before building the image in order to produce a +correctly configured image. + +When your build is complete, your packages reside in the +``${TMPDIR}/deploy/packageformat`` directory. For example, if +``${``\ :term:`TMPDIR`\ ``}`` is +``tmp`` and your selected package type is RPM, then your RPM packages +are available in ``tmp/deploy/rpm``. + +Host or Server Machine Setup +---------------------------- + +Although other protocols are possible, a server using HTTP typically +serves packages. If you want to use HTTP, then set up and configure a +web server such as Apache 2, lighttpd, or Python web server on the +machine serving the packages. + +To keep things simple, this section describes how to set up a +Python web server to share package feeds from the developer's +machine. Although this server might not be the best for a production +environment, the setup is simple and straight forward. Should you want +to use a different server more suited for production (e.g. Apache 2, +Lighttpd, or Nginx), take the appropriate steps to do so. + +From within the :term:`Build Directory` where you have built an image based on +your packaging choice (i.e. the :term:`PACKAGE_CLASSES` setting), simply start +the server. The following example assumes a :term:`Build Directory` of ``poky/build`` +and a :term:`PACKAGE_CLASSES` setting of ":ref:`ref-classes-package_rpm`":: + + $ cd poky/build/tmp/deploy/rpm + $ python3 -m http.server + +Target Setup +------------ + +Setting up the target differs depending on the package management +system. This section provides information for RPM, IPK, and DEB. + +Using RPM +~~~~~~~~~ + +The :wikipedia:`Dandified Packaging ` (DNF) performs +runtime package management of RPM packages. In order to use DNF for +runtime package management, you must perform an initial setup on the +target machine for cases where the ``PACKAGE_FEED_*`` variables were not +set as part of the image that is running on the target. This means if +you built your image and did not use these variables as part of the +build and your image is now running on the target, you need to perform +the steps in this section if you want to use runtime package management. + +.. note:: + + For information on the ``PACKAGE_FEED_*`` variables, see + :term:`PACKAGE_FEED_ARCHS`, :term:`PACKAGE_FEED_BASE_PATHS`, and + :term:`PACKAGE_FEED_URIS` in the Yocto Project Reference Manual variables + glossary. + +On the target, you must inform DNF that package databases are available. +You do this by creating a file named +``/etc/yum.repos.d/oe-packages.repo`` and defining the ``oe-packages``. + +As an example, assume the target is able to use the following package +databases: ``all``, ``i586``, and ``qemux86`` from a server named +``my.server``. The specifics for setting up the web server are up to +you. The critical requirement is that the URIs in the target repository +configuration point to the correct remote location for the feeds. + +.. note:: + + For development purposes, you can point the web server to the build + system's ``deploy`` directory. However, for production use, it is better to + copy the package directories to a location outside of the build area and use + that location. Doing so avoids situations where the build system + overwrites or changes the ``deploy`` directory. + +When telling DNF where to look for the package databases, you must +declare individual locations per architecture or a single location used +for all architectures. You cannot do both: + +- *Create an Explicit List of Architectures:* Define individual base + URLs to identify where each package database is located: + + .. code-block:: none + + [oe-packages] + baseurl=http://my.server/rpm/i586 http://my.server/rpm/qemux86 http://my.server/rpm/all + + This example + informs DNF about individual package databases for all three + architectures. + +- *Create a Single (Full) Package Index:* Define a single base URL that + identifies where a full package database is located:: + + [oe-packages] + baseurl=http://my.server/rpm + + This example informs DNF about a single + package database that contains all the package index information for + all supported architectures. + +Once you have informed DNF where to find the package databases, you need +to fetch them: + +.. code-block:: none + + # dnf makecache + +DNF is now able to find, install, and +upgrade packages from the specified repository or repositories. + +.. note:: + + See the `DNF documentation `__ for + additional information. + +Using IPK +~~~~~~~~~ + +The ``opkg`` application performs runtime package management of IPK +packages. You must perform an initial setup for ``opkg`` on the target +machine if the +:term:`PACKAGE_FEED_ARCHS`, +:term:`PACKAGE_FEED_BASE_PATHS`, +and +:term:`PACKAGE_FEED_URIS` +variables have not been set or the target image was built before the +variables were set. + +The ``opkg`` application uses configuration files to find available +package databases. Thus, you need to create a configuration file inside +the ``/etc/opkg/`` directory, which informs ``opkg`` of any repository +you want to use. + +As an example, suppose you are serving packages from a ``ipk/`` +directory containing the ``i586``, ``all``, and ``qemux86`` databases +through an HTTP server named ``my.server``. On the target, create a +configuration file (e.g. ``my_repo.conf``) inside the ``/etc/opkg/`` +directory containing the following: + +.. code-block:: none + + src/gz all http://my.server/ipk/all + src/gz i586 http://my.server/ipk/i586 + src/gz qemux86 http://my.server/ipk/qemux86 + +Next, instruct ``opkg`` to fetch the +repository information: + +.. code-block:: none + + # opkg update + +The ``opkg`` application is now able to find, install, and upgrade packages +from the specified repository. + +Using DEB +~~~~~~~~~ + +The ``apt`` application performs runtime package management of DEB +packages. This application uses a source list file to find available +package databases. You must perform an initial setup for ``apt`` on the +target machine if the +:term:`PACKAGE_FEED_ARCHS`, +:term:`PACKAGE_FEED_BASE_PATHS`, +and +:term:`PACKAGE_FEED_URIS` +variables have not been set or the target image was built before the +variables were set. + +To inform ``apt`` of the repository you want to use, you might create a +list file (e.g. ``my_repo.list``) inside the +``/etc/apt/sources.list.d/`` directory. As an example, suppose you are +serving packages from a ``deb/`` directory containing the ``i586``, +``all``, and ``qemux86`` databases through an HTTP server named +``my.server``. The list file should contain: + +.. code-block:: none + + deb http://my.server/deb/all ./ + deb http://my.server/deb/i586 ./ + deb http://my.server/deb/qemux86 ./ + +Next, instruct the ``apt`` application +to fetch the repository information: + +.. code-block:: none + + $ sudo apt update + +After this step, +``apt`` is able to find, install, and upgrade packages from the +specified repository. + +Generating and Using Signed Packages +==================================== + +In order to add security to RPM packages used during a build, you can +take steps to securely sign them. Once a signature is verified, the +OpenEmbedded build system can use the package in the build. If security +fails for a signed package, the build system stops the build. + +This section describes how to sign RPM packages during a build and how +to use signed package feeds (repositories) when doing a build. + +Signing RPM Packages +-------------------- + +To enable signing RPM packages, you must set up the following +configurations in either your ``local.config`` or ``distro.config`` +file:: + + # Inherit sign_rpm.bbclass to enable signing functionality + INHERIT += " sign_rpm" + # Define the GPG key that will be used for signing. + RPM_GPG_NAME = "key_name" + # Provide passphrase for the key + RPM_GPG_PASSPHRASE = "passphrase" + +.. note:: + + Be sure to supply appropriate values for both `key_name` and + `passphrase`. + +Aside from the ``RPM_GPG_NAME`` and ``RPM_GPG_PASSPHRASE`` variables in +the previous example, two optional variables related to signing are available: + +- *GPG_BIN:* Specifies a ``gpg`` binary/wrapper that is executed + when the package is signed. + +- *GPG_PATH:* Specifies the ``gpg`` home directory used when the + package is signed. + +Processing Package Feeds +------------------------ + +In addition to being able to sign RPM packages, you can also enable +signed package feeds for IPK and RPM packages. + +The steps you need to take to enable signed package feed use are similar +to the steps used to sign RPM packages. You must define the following in +your ``local.config`` or ``distro.config`` file:: + + INHERIT += "sign_package_feed" + PACKAGE_FEED_GPG_NAME = "key_name" + PACKAGE_FEED_GPG_PASSPHRASE_FILE = "path_to_file_containing_passphrase" + +For signed package feeds, the passphrase must be specified in a separate file, +which is pointed to by the ``PACKAGE_FEED_GPG_PASSPHRASE_FILE`` +variable. Regarding security, keeping a plain text passphrase out of the +configuration is more secure. + +Aside from the ``PACKAGE_FEED_GPG_NAME`` and +``PACKAGE_FEED_GPG_PASSPHRASE_FILE`` variables, three optional variables +related to signed package feeds are available: + +- *GPG_BIN* Specifies a ``gpg`` binary/wrapper that is executed + when the package is signed. + +- *GPG_PATH:* Specifies the ``gpg`` home directory used when the + package is signed. + +- *PACKAGE_FEED_GPG_SIGNATURE_TYPE:* Specifies the type of ``gpg`` + signature. This variable applies only to RPM and IPK package feeds. + Allowable values for the ``PACKAGE_FEED_GPG_SIGNATURE_TYPE`` are + "ASC", which is the default and specifies ascii armored, and "BIN", + which specifies binary. + +Testing Packages With ptest +=========================== + +A Package Test (ptest) runs tests against packages built by the +OpenEmbedded build system on the target machine. A ptest contains at +least two items: the actual test, and a shell script (``run-ptest``) +that starts the test. The shell script that starts the test must not +contain the actual test --- the script only starts the test. On the other +hand, the test can be anything from a simple shell script that runs a +binary and checks the output to an elaborate system of test binaries and +data files. + +The test generates output in the format used by Automake:: + + result: testname + +where the result can be ``PASS``, ``FAIL``, or ``SKIP``, and +the testname can be any identifying string. + +For a list of Yocto Project recipes that are already enabled with ptest, +see the :yocto_wiki:`Ptest ` wiki page. + +.. note:: + + A recipe is "ptest-enabled" if it inherits the :ref:`ref-classes-ptest` + class. + +Adding ptest to Your Build +-------------------------- + +To add package testing to your build, add the :term:`DISTRO_FEATURES` and +:term:`EXTRA_IMAGE_FEATURES` variables to your ``local.conf`` file, which +is found in the :term:`Build Directory`:: + + DISTRO_FEATURES:append = " ptest" + EXTRA_IMAGE_FEATURES += "ptest-pkgs" + +Once your build is complete, the ptest files are installed into the +``/usr/lib/package/ptest`` directory within the image, where ``package`` +is the name of the package. + +Running ptest +------------- + +The ``ptest-runner`` package installs a shell script that loops through +all installed ptest test suites and runs them in sequence. Consequently, +you might want to add this package to your image. + +Getting Your Package Ready +-------------------------- + +In order to enable a recipe to run installed ptests on target hardware, +you need to prepare the recipes that build the packages you want to +test. Here is what you have to do for each recipe: + +- *Be sure the recipe inherits the* :ref:`ref-classes-ptest` *class:* + Include the following line in each recipe:: + + inherit ptest + +- *Create run-ptest:* This script starts your test. Locate the + script where you will refer to it using + :term:`SRC_URI`. Here is an + example that starts a test for ``dbus``:: + + #!/bin/sh + cd test + make -k runtest-TESTS + +- *Ensure dependencies are met:* If the test adds build or runtime + dependencies that normally do not exist for the package (such as + requiring "make" to run the test suite), use the + :term:`DEPENDS` and + :term:`RDEPENDS` variables in + your recipe in order for the package to meet the dependencies. Here + is an example where the package has a runtime dependency on "make":: + + RDEPENDS:${PN}-ptest += "make" + +- *Add a function to build the test suite:* Not many packages support + cross-compilation of their test suites. Consequently, you usually + need to add a cross-compilation function to the package. + + Many packages based on Automake compile and run the test suite by + using a single command such as ``make check``. However, the host + ``make check`` builds and runs on the same computer, while + cross-compiling requires that the package is built on the host but + executed for the target architecture (though often, as in the case + for ptest, the execution occurs on the host). The built version of + Automake that ships with the Yocto Project includes a patch that + separates building and execution. Consequently, packages that use the + unaltered, patched version of ``make check`` automatically + cross-compiles. + + Regardless, you still must add a ``do_compile_ptest`` function to + build the test suite. Add a function similar to the following to your + recipe:: + + do_compile_ptest() { + oe_runmake buildtest-TESTS + } + +- *Ensure special configurations are set:* If the package requires + special configurations prior to compiling the test code, you must + insert a ``do_configure_ptest`` function into the recipe. + +- *Install the test suite:* The :ref:`ref-classes-ptest` class + automatically copies the file ``run-ptest`` to the target and then runs make + ``install-ptest`` to run the tests. If this is not enough, you need + to create a ``do_install_ptest`` function and make sure it gets + called after the "make install-ptest" completes. + +Creating Node Package Manager (NPM) Packages +============================================ + +:wikipedia:`NPM ` is a package manager for the JavaScript +programming language. The Yocto Project supports the NPM +:ref:`fetcher `. +You can use this fetcher in combination with +:doc:`devtool ` to create recipes that produce +NPM packages. + +There are two workflows that allow you to create NPM packages using +``devtool``: the NPM registry modules method and the NPM project code +method. + +.. note:: + + While it is possible to create NPM recipes manually, using + ``devtool`` is far simpler. + +Additionally, some requirements and caveats exist. + +Requirements and Caveats +------------------------ + +You need to be aware of the following before using ``devtool`` to create +NPM packages: + +- Of the two methods that you can use ``devtool`` to create NPM + packages, the registry approach is slightly simpler. However, you + might consider the project approach because you do not have to + publish your module in the `NPM registry `__, + which is NPM's public registry. + +- Be familiar with + :doc:`devtool `. + +- The NPM host tools need the native ``nodejs-npm`` package, which is + part of the OpenEmbedded environment. You need to get the package by + cloning the :oe_git:`meta-openembedded ` + repository. Be sure to add the path to your local copy + to your ``bblayers.conf`` file. + +- ``devtool`` cannot detect native libraries in module dependencies. + Consequently, you must manually add packages to your recipe. + +- While deploying NPM packages, ``devtool`` cannot determine which + dependent packages are missing on the target (e.g. the node runtime + ``nodejs``). Consequently, you need to find out what files are + missing and be sure they are on the target. + +- Although you might not need NPM to run your node package, it is + useful to have NPM on your target. The NPM package name is + ``nodejs-npm``. + +Using the Registry Modules Method +--------------------------------- + +This section presents an example that uses the ``cute-files`` module, +which is a file browser web application. + +.. note:: + + You must know the ``cute-files`` module version. + +The first thing you need to do is use ``devtool`` and the NPM fetcher to +create the recipe:: + + $ devtool add "npm://registry.npmjs.org;package=cute-files;version=1.0.2" + +The +``devtool add`` command runs ``recipetool create`` and uses the same +fetch URI to download each dependency and capture license details where +possible. The result is a generated recipe. + +After running for quite a long time, in particular building the +``nodejs-native`` package, the command should end as follows:: + + INFO: Recipe /home/.../build/workspace/recipes/cute-files/cute-files_1.0.2.bb has been automatically created; further editing may be required to make it fully functional + +The recipe file is fairly simple and contains every license that +``recipetool`` finds and includes the licenses in the recipe's +:term:`LIC_FILES_CHKSUM` +variables. You need to examine the variables and look for those with +"unknown" in the :term:`LICENSE` +field. You need to track down the license information for "unknown" +modules and manually add the information to the recipe. + +``recipetool`` creates a "shrinkwrap" file for your recipe. Shrinkwrap +files capture the version of all dependent modules. Many packages do not +provide shrinkwrap files but ``recipetool`` will create a shrinkwrap file as it +runs. + +.. note:: + + A package is created for each sub-module. This policy is the only + practical way to have the licenses for all of the dependencies + represented in the license manifest of the image. + +The ``devtool edit-recipe`` command lets you take a look at the recipe:: + + $ devtool edit-recipe cute-files + # Recipe created by recipetool + # This is the basis of a recipe and may need further editing in order to be fully functional. + # (Feel free to remove these comments when editing.) + + SUMMARY = "Turn any folder on your computer into a cute file browser, available on the local network." + # WARNING: the following LICENSE and LIC_FILES_CHKSUM values are best guesses - it is + # your responsibility to verify that the values are complete and correct. + # + # NOTE: multiple licenses have been detected; they have been separated with & + # in the LICENSE value for now since it is a reasonable assumption that all + # of the licenses apply. If instead there is a choice between the multiple + # licenses then you should change the value to separate the licenses with | + # instead of &. If there is any doubt, check the accompanying documentation + # to determine which situation is applicable. + + SUMMARY = "Turn any folder on your computer into a cute file browser, available on the local network." + LICENSE = "BSD-3-Clause & ISC & MIT" + LIC_FILES_CHKSUM = "file://LICENSE;md5=71d98c0a1db42956787b1909c74a86ca \ + file://node_modules/accepts/LICENSE;md5=bf1f9ad1e2e1d507aef4883fff7103de \ + file://node_modules/array-flatten/LICENSE;md5=44088ba57cb871a58add36ce51b8de08 \ + ... + file://node_modules/cookie-signature/Readme.md;md5=57ae8b42de3dd0c1f22d5f4cf191e15a" + + SRC_URI = " \ + npm://registry.npmjs.org/;package=cute-files;version=${PV} \ + npmsw://${THISDIR}/${BPN}/npm-shrinkwrap.json \ + " + + S = "${WORKDIR}/npm" + + inherit npm + + LICENSE:${PN} = "MIT" + LICENSE:${PN}-accepts = "MIT" + LICENSE:${PN}-array-flatten = "MIT" + ... + LICENSE:${PN}-vary = "MIT" + +Here are three key points in the previous example: + +- :term:`SRC_URI` uses the NPM + scheme so that the NPM fetcher is used. + +- ``recipetool`` collects all the license information. If a + sub-module's license is unavailable, the sub-module's name appears in + the comments. + +- The ``inherit npm`` statement causes the :ref:`ref-classes-npm` class to + package up all the modules. + +You can run the following command to build the ``cute-files`` package:: + + $ devtool build cute-files + +Remember that ``nodejs`` must be installed on +the target before your package. + +Assuming 192.168.7.2 for the target's IP address, use the following +command to deploy your package:: + + $ devtool deploy-target -s cute-files root@192.168.7.2 + +Once the package is installed on the target, you can +test the application to show the contents of any directory:: + + $ cd /usr/lib/node_modules/cute-files + $ cute-files + +On a browser, +go to ``http://192.168.7.2:3000`` and you see the following: + +.. image:: figures/cute-files-npm-example.png + :width: 100% + +You can find the recipe in ``workspace/recipes/cute-files``. You can use +the recipe in any layer you choose. + +Using the NPM Projects Code Method +---------------------------------- + +Although it is useful to package modules already in the NPM registry, +adding ``node.js`` projects under development is a more common developer +use case. + +This section covers the NPM projects code method, which is very similar +to the "registry" approach described in the previous section. In the NPM +projects method, you provide ``devtool`` with an URL that points to the +source files. + +Replicating the same example, (i.e. ``cute-files``) use the following +command:: + + $ devtool add https://github.com/martinaglv/cute-files.git + +The recipe this command generates is very similar to the recipe created in +the previous section. However, the :term:`SRC_URI` looks like the following:: + + SRC_URI = " \ + git://github.com/martinaglv/cute-files.git;protocol=https;branch=master \ + npmsw://${THISDIR}/${BPN}/npm-shrinkwrap.json \ + " + +In this example, +the main module is taken from the Git repository and dependencies are +taken from the NPM registry. Other than those differences, the recipe is +basically the same between the two methods. You can build and deploy the +package exactly as described in the previous section that uses the +registry modules method. + +Adding custom metadata to packages +================================== + +The variable +:term:`PACKAGE_ADD_METADATA` +can be used to add additional metadata to packages. This is reflected in +the package control/spec file. To take the ipk format for example, the +CONTROL file stored inside would contain the additional metadata as +additional lines. + +The variable can be used in multiple ways, including using suffixes to +set it for a specific package type and/or package. Note that the order +of precedence is the same as this list: + +- ``PACKAGE_ADD_METADATA_:`` + +- ``PACKAGE_ADD_METADATA_`` + +- ``PACKAGE_ADD_METADATA:`` + +- :term:`PACKAGE_ADD_METADATA` + +`` is a parameter and expected to be a distinct name of specific +package type: + +- IPK for .ipk packages + +- DEB for .deb packages + +- RPM for .rpm packages + +`` is a parameter and expected to be a package name. + +The variable can contain multiple [one-line] metadata fields separated +by the literal sequence '\\n'. The separator can be redefined using the +variable flag ``separator``. + +Here is an example that adds two custom fields for ipk +packages:: + + PACKAGE_ADD_METADATA_IPK = "Vendor: CustomIpk\nGroup:Applications/Spreadsheets" + diff --git a/documentation/dev-manual/prebuilt-libraries.rst b/documentation/dev-manual/prebuilt-libraries.rst new file mode 100644 index 0000000000..b80a844e93 --- /dev/null +++ b/documentation/dev-manual/prebuilt-libraries.rst @@ -0,0 +1,209 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Working with Pre-Built Libraries +******************************** + +Introduction +============ + +Some library vendors do not release source code for their software but do +release pre-built binaries. When shared libraries are built, they should +be versioned (see `this article +`__ +for some background), but sometimes this is not done. + +To summarize, a versioned library must meet two conditions: + +#. The filename must have the version appended, for example: ``libfoo.so.1.2.3``. +#. The library must have the ELF tag ``SONAME`` set to the major version + of the library, for example: ``libfoo.so.1``. You can check this by + running ``readelf -d filename | grep SONAME``. + +This section shows how to deal with both versioned and unversioned +pre-built libraries. + +Versioned Libraries +=================== + +In this example we work with pre-built libraries for the FT4222H USB I/O chip. +Libraries are built for several target architecture variants and packaged in +an archive as follows:: + + ├── build-arm-hisiv300 + │   └── libft4222.so.1.4.4.44 + ├── build-arm-v5-sf + │   └── libft4222.so.1.4.4.44 + ├── build-arm-v6-hf + │   └── libft4222.so.1.4.4.44 + ├── build-arm-v7-hf + │   └── libft4222.so.1.4.4.44 + ├── build-arm-v8 + │   └── libft4222.so.1.4.4.44 + ├── build-i386 + │   └── libft4222.so.1.4.4.44 + ├── build-i486 + │   └── libft4222.so.1.4.4.44 + ├── build-mips-eglibc-hf + │   └── libft4222.so.1.4.4.44 + ├── build-pentium + │   └── libft4222.so.1.4.4.44 + ├── build-x86_64 + │   └── libft4222.so.1.4.4.44 + ├── examples + │   ├── get-version.c + │   ├── i2cm.c + │   ├── spim.c + │   └── spis.c + ├── ftd2xx.h + ├── install4222.sh + ├── libft4222.h + ├── ReadMe.txt + └── WinTypes.h + +To write a recipe to use such a library in your system: + +- The vendor will probably have a proprietary licence, so set + :term:`LICENSE_FLAGS` in your recipe. +- The vendor provides a tarball containing libraries so set :term:`SRC_URI` + appropriately. +- Set :term:`COMPATIBLE_HOST` so that the recipe cannot be used with an + unsupported architecture. In the following example, we only support the 32 + and 64 bit variants of the ``x86`` architecture. +- As the vendor provides versioned libraries, we can use ``oe_soinstall`` + from :ref:`ref-classes-utils` to install the shared library and create + symbolic links. If the vendor does not do this, we need to follow the + non-versioned library guidelines in the next section. +- As the vendor likely used :term:`LDFLAGS` different from those in your Yocto + Project build, disable the corresponding checks by adding ``ldflags`` + to :term:`INSANE_SKIP`. +- The vendor will typically ship release builds without debugging symbols. + Avoid errors by preventing the packaging task from stripping out the symbols + and adding them to a separate debug package. This is done by setting the + ``INHIBIT_`` flags shown below. + +The complete recipe would look like this:: + + SUMMARY = "FTDI FT4222H Library" + SECTION = "libs" + LICENSE_FLAGS = "ftdi" + LICENSE = "CLOSED" + + COMPATIBLE_HOST = "(i.86|x86_64).*-linux" + + # Sources available in a .tgz file in .zip archive + # at https://ftdichip.com/wp-content/uploads/2021/01/libft4222-linux-1.4.4.44.zip + # Found on https://ftdichip.com/software-examples/ft4222h-software-examples/ + # Since dealing with this particular type of archive is out of topic here, + # we use a local link. + SRC_URI = "file://libft4222-linux-${PV}.tgz" + + S = "${WORKDIR}" + + ARCH_DIR:x86-64 = "build-x86_64" + ARCH_DIR:i586 = "build-i386" + ARCH_DIR:i686 = "build-i386" + + INSANE_SKIP:${PN} = "ldflags" + INHIBIT_PACKAGE_STRIP = "1" + INHIBIT_SYSROOT_STRIP = "1" + INHIBIT_PACKAGE_DEBUG_SPLIT = "1" + + do_install () { + install -m 0755 -d ${D}${libdir} + oe_soinstall ${S}/${ARCH_DIR}/libft4222.so.${PV} ${D}${libdir} + install -d ${D}${includedir} + install -m 0755 ${S}/*.h ${D}${includedir} + } + +If the precompiled binaries are not statically linked and have dependencies on +other libraries, then by adding those libraries to :term:`DEPENDS`, the linking +can be examined and the appropriate :term:`RDEPENDS` automatically added. + +Non-Versioned Libraries +======================= + +Some Background +--------------- + +Libraries in Linux systems are generally versioned so that it is possible +to have multiple versions of the same library installed, which eases upgrades +and support for older software. For example, suppose that in a versioned +library, an actual library is called ``libfoo.so.1.2``, a symbolic link named +``libfoo.so.1`` points to ``libfoo.so.1.2``, and a symbolic link named +``libfoo.so`` points to ``libfoo.so.1.2``. Given these conditions, when you +link a binary against a library, you typically provide the unversioned file +name (i.e. ``-lfoo`` to the linker). However, the linker follows the symbolic +link and actually links against the versioned filename. The unversioned symbolic +link is only used at development time. Consequently, the library is packaged +along with the headers in the development package ``${PN}-dev`` along with the +actual library and versioned symbolic links in ``${PN}``. Because versioned +libraries are far more common than unversioned libraries, the default packaging +rules assume versioned libraries. + +Yocto Library Packaging Overview +-------------------------------- + +It follows that packaging an unversioned library requires a bit of work in the +recipe. By default, ``libfoo.so`` gets packaged into ``${PN}-dev``, which +triggers a QA warning that a non-symlink library is in a ``-dev`` package, +and binaries in the same recipe link to the library in ``${PN}-dev``, +which triggers more QA warnings. To solve this problem, you need to package the +unversioned library into ``${PN}`` where it belongs. The following are the abridged +default :term:`FILES` variables in ``bitbake.conf``:: + + SOLIBS = ".so.*" + SOLIBSDEV = ".so" + FILES:${PN} = "... ${libdir}/lib*${SOLIBS} ..." + FILES_SOLIBSDEV ?= "... ${libdir}/lib*${SOLIBSDEV} ..." + FILES:${PN}-dev = "... ${FILES_SOLIBSDEV} ..." + +:term:`SOLIBS` defines a pattern that matches real shared object libraries. +:term:`SOLIBSDEV` matches the development form (unversioned symlink). These two +variables are then used in ``FILES:${PN}`` and ``FILES:${PN}-dev``, which puts +the real libraries into ``${PN}`` and the unversioned symbolic link into ``${PN}-dev``. +To package unversioned libraries, you need to modify the variables in the recipe +as follows:: + + SOLIBS = ".so" + FILES_SOLIBSDEV = "" + +The modifications cause the ``.so`` file to be the real library +and unset :term:`FILES_SOLIBSDEV` so that no libraries get packaged into +``${PN}-dev``. The changes are required because unless :term:`PACKAGES` is changed, +``${PN}-dev`` collects files before `${PN}`. ``${PN}-dev`` must not collect any of +the files you want in ``${PN}``. + +Finally, loadable modules, essentially unversioned libraries that are linked +at runtime using ``dlopen()`` instead of at build time, should generally be +installed in a private directory. However, if they are installed in ``${libdir}``, +then the modules can be treated as unversioned libraries. + +Example +------- + +The example below installs an unversioned x86-64 pre-built library named +``libfoo.so``. The :term:`COMPATIBLE_HOST` variable limits recipes to the +x86-64 architecture while the :term:`INSANE_SKIP`, :term:`INHIBIT_PACKAGE_STRIP` +and :term:`INHIBIT_SYSROOT_STRIP` variables are all set as in the above +versioned library example. The "magic" is setting the :term:`SOLIBS` and +:term:`FILES_SOLIBSDEV` variables as explained above:: + + SUMMARY = "libfoo sample recipe" + SECTION = "libs" + LICENSE = "CLOSED" + + SRC_URI = "file://libfoo.so" + + COMPATIBLE_HOST = "x86_64.*-linux" + + INSANE_SKIP:${PN} = "ldflags" + INHIBIT_PACKAGE_STRIP = "1" + INHIBIT_SYSROOT_STRIP = "1" + SOLIBS = ".so" + FILES_SOLIBSDEV = "" + + do_install () { + install -d ${D}${libdir} + install -m 0755 ${WORKDIR}/libfoo.so ${D}${libdir} + } + diff --git a/documentation/dev-manual/python-development-shell.rst b/documentation/dev-manual/python-development-shell.rst new file mode 100644 index 0000000000..2dc6a3f138 --- /dev/null +++ b/documentation/dev-manual/python-development-shell.rst @@ -0,0 +1,50 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Using a Python Development Shell +******************************** + +Similar to working within a development shell as described in the +previous section, you can also spawn and work within an interactive +Python development shell. When debugging certain commands or even when +just editing packages, ``pydevshell`` can be a useful tool. When you +invoke the ``pydevshell`` task, all tasks up to and including +:ref:`ref-tasks-patch` are run for the +specified target. Then a new terminal is opened. Additionally, key +Python objects and code are available in the same way they are to +BitBake tasks, in particular, the data store 'd'. So, commands such as +the following are useful when exploring the data store and running +functions:: + + pydevshell> d.getVar("STAGING_DIR") + '/media/build1/poky/build/tmp/sysroots' + pydevshell> d.getVar("STAGING_DIR", False) + '${TMPDIR}/sysroots' + pydevshell> d.setVar("FOO", "bar") + pydevshell> d.getVar("FOO") + 'bar' + pydevshell> d.delVar("FOO") + pydevshell> d.getVar("FOO") + pydevshell> bb.build.exec_func("do_unpack", d) + pydevshell> + +See the ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:functions you can call from within python`" +section in the BitBake User Manual for details about available functions. + +The commands execute just as if the OpenEmbedded build +system were executing them. Consequently, working this way can be +helpful when debugging a build or preparing software to be used with the +OpenEmbedded build system. + +Following is an example that uses ``pydevshell`` on a target named +``matchbox-desktop``:: + + $ bitbake matchbox-desktop -c pydevshell + +This command spawns a terminal and places you in an interactive Python +interpreter within the OpenEmbedded build environment. The +:term:`OE_TERMINAL` variable +controls what type of shell is opened. + +When you are finished using ``pydevshell``, you can exit the shell +either by using Ctrl+d or closing the terminal window. + diff --git a/documentation/dev-manual/quilt.rst b/documentation/dev-manual/quilt.rst new file mode 100644 index 0000000000..59240705ad --- /dev/null +++ b/documentation/dev-manual/quilt.rst @@ -0,0 +1,89 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Using Quilt in Your Workflow +**************************** + +`Quilt `__ is a powerful tool +that allows you to capture source code changes without having a clean +source tree. This section outlines the typical workflow you can use to +modify source code, test changes, and then preserve the changes in the +form of a patch all using Quilt. + +.. note:: + + With regard to preserving changes to source files, if you clean a + recipe or have :ref:`ref-classes-rm-work` enabled, the + :ref:`devtool workflow ` + as described in the Yocto Project Application Development and the + Extensible Software Development Kit (eSDK) manual is a safer + development flow than the flow that uses Quilt. + +Follow these general steps: + +#. *Find the Source Code:* Temporary source code used by the + OpenEmbedded build system is kept in the :term:`Build Directory`. See the + ":ref:`dev-manual/temporary-source-code:finding temporary source code`" section to + learn how to locate the directory that has the temporary source code for a + particular package. + +#. *Change Your Working Directory:* You need to be in the directory that + has the temporary source code. That directory is defined by the + :term:`S` variable. + +#. *Create a New Patch:* Before modifying source code, you need to + create a new patch. To create a new patch file, use ``quilt new`` as + below:: + + $ quilt new my_changes.patch + +#. *Notify Quilt and Add Files:* After creating the patch, you need to + notify Quilt about the files you plan to edit. You notify Quilt by + adding the files to the patch you just created:: + + $ quilt add file1.c file2.c file3.c + +#. *Edit the Files:* Make your changes in the source code to the files + you added to the patch. + +#. *Test Your Changes:* Once you have modified the source code, the + easiest way to test your changes is by calling the :ref:`ref-tasks-compile` + task as shown in the following example:: + + $ bitbake -c compile -f package + + The ``-f`` or ``--force`` option forces the specified task to + execute. If you find problems with your code, you can just keep + editing and re-testing iteratively until things work as expected. + + .. note:: + + All the modifications you make to the temporary source code disappear + once you run the :ref:`ref-tasks-clean` or :ref:`ref-tasks-cleanall` + tasks using BitBake (i.e. ``bitbake -c clean package`` and + ``bitbake -c cleanall package``). Modifications will also disappear if + you use the :ref:`ref-classes-rm-work` feature as described in + the ":ref:`dev-manual/disk-space:conserving disk space during builds`" + section. + +#. *Generate the Patch:* Once your changes work as expected, you need to + use Quilt to generate the final patch that contains all your + modifications:: + + $ quilt refresh + + At this point, the + ``my_changes.patch`` file has all your edits made to the ``file1.c``, + ``file2.c``, and ``file3.c`` files. + + You can find the resulting patch file in the ``patches/`` + subdirectory of the source (:term:`S`) directory. + +#. *Copy the Patch File:* For simplicity, copy the patch file into a + directory named ``files``, which you can create in the same directory + that holds the recipe (``.bb``) file or the append (``.bbappend``) + file. Placing the patch here guarantees that the OpenEmbedded build + system will find the patch. Next, add the patch into the :term:`SRC_URI` + of the recipe. Here is an example:: + + SRC_URI += "file://my_changes.patch" + diff --git a/documentation/dev-manual/read-only-rootfs.rst b/documentation/dev-manual/read-only-rootfs.rst new file mode 100644 index 0000000000..251178ed54 --- /dev/null +++ b/documentation/dev-manual/read-only-rootfs.rst @@ -0,0 +1,89 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Creating a Read-Only Root Filesystem +************************************ + +Suppose, for security reasons, you need to disable your target device's +root filesystem's write permissions (i.e. you need a read-only root +filesystem). Or, perhaps you are running the device's operating system +from a read-only storage device. For either case, you can customize your +image for that behavior. + +.. note:: + + Supporting a read-only root filesystem requires that the system and + applications do not try to write to the root filesystem. You must + configure all parts of the target system to write elsewhere, or to + gracefully fail in the event of attempting to write to the root + filesystem. + +Creating the Root Filesystem +============================ + +To create the read-only root filesystem, simply add the +"read-only-rootfs" feature to your image, normally in one of two ways. +The first way is to add the "read-only-rootfs" image feature in the +image's recipe file via the :term:`IMAGE_FEATURES` variable:: + + IMAGE_FEATURES += "read-only-rootfs" + +As an alternative, you can add the same feature +from within your :term:`Build Directory`'s ``local.conf`` file with the +associated :term:`EXTRA_IMAGE_FEATURES` variable, as in:: + + EXTRA_IMAGE_FEATURES = "read-only-rootfs" + +For more information on how to use these variables, see the +":ref:`dev-manual/customizing-images:Customizing Images Using Custom \`\`IMAGE_FEATURES\`\` and \`\`EXTRA_IMAGE_FEATURES\`\``" +section. For information on the variables, see +:term:`IMAGE_FEATURES` and +:term:`EXTRA_IMAGE_FEATURES`. + +Post-Installation Scripts and Read-Only Root Filesystem +======================================================= + +It is very important that you make sure all post-Installation +(``pkg_postinst``) scripts for packages that are installed into the +image can be run at the time when the root filesystem is created during +the build on the host system. These scripts cannot attempt to run during +the first boot on the target device. With the "read-only-rootfs" feature +enabled, the build system makes sure that all post-installation scripts +succeed at file system creation time. If any of these scripts +still need to be run after the root filesystem is created, the build +immediately fails. These build-time checks ensure that the build fails +rather than the target device fails later during its initial boot +operation. + +Most of the common post-installation scripts generated by the build +system for the out-of-the-box Yocto Project are engineered so that they +can run during root filesystem creation (e.g. post-installation scripts +for caching fonts). However, if you create and add custom scripts, you +need to be sure they can be run during this file system creation. + +Here are some common problems that prevent post-installation scripts +from running during root filesystem creation: + +- *Not using $D in front of absolute paths:* The build system defines + ``$``\ :term:`D` when the root + filesystem is created. Furthermore, ``$D`` is blank when the script + is run on the target device. This implies two purposes for ``$D``: + ensuring paths are valid in both the host and target environments, + and checking to determine which environment is being used as a method + for taking appropriate actions. + +- *Attempting to run processes that are specific to or dependent on the + target architecture:* You can work around these attempts by using + native tools, which run on the host system, to accomplish the same + tasks, or by alternatively running the processes under QEMU, which + has the ``qemu_run_binary`` function. For more information, see the + :ref:`ref-classes-qemu` class. + +Areas With Write Access +======================= + +With the "read-only-rootfs" feature enabled, any attempt by the target +to write to the root filesystem at runtime fails. Consequently, you must +make sure that you configure processes and applications that attempt +these types of writes do so to directories with write access (e.g. +``/tmp`` or ``/var/run``). + diff --git a/documentation/dev-manual/runtime-testing.rst b/documentation/dev-manual/runtime-testing.rst new file mode 100644 index 0000000000..a5d8502fbb --- /dev/null +++ b/documentation/dev-manual/runtime-testing.rst @@ -0,0 +1,598 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Performing Automated Runtime Testing +************************************ + +The OpenEmbedded build system makes available a series of automated +tests for images to verify runtime functionality. You can run these +tests on either QEMU or actual target hardware. Tests are written in +Python making use of the ``unittest`` module, and the majority of them +run commands on the target system over SSH. This section describes how +you set up the environment to use these tests, run available tests, and +write and add your own tests. + +For information on the test and QA infrastructure available within the +Yocto Project, see the ":ref:`ref-manual/release-process:testing and quality assurance`" +section in the Yocto Project Reference Manual. + +Enabling Tests +============== + +Depending on whether you are planning to run tests using QEMU or on the +hardware, you have to take different steps to enable the tests. See the +following subsections for information on how to enable both types of +tests. + +Enabling Runtime Tests on QEMU +------------------------------ + +In order to run tests, you need to do the following: + +- *Set up to avoid interaction with sudo for networking:* To + accomplish this, you must do one of the following: + + - Add ``NOPASSWD`` for your user in ``/etc/sudoers`` either for all + commands or just for ``runqemu-ifup``. You must provide the full + path as that can change if you are using multiple clones of the + source repository. + + .. note:: + + On some distributions, you also need to comment out "Defaults + requiretty" in ``/etc/sudoers``. + + - Manually configure a tap interface for your system. + + - Run as root the script in ``scripts/runqemu-gen-tapdevs``, which + should generate a list of tap devices. This is the option + typically chosen for Autobuilder-type environments. + + .. note:: + + - Be sure to use an absolute path when calling this script + with sudo. + + - The package recipe ``qemu-helper-native`` is required to run + this script. Build the package using the following command:: + + $ bitbake qemu-helper-native + +- *Set the DISPLAY variable:* You need to set this variable so that + you have an X server available (e.g. start ``vncserver`` for a + headless machine). + +- *Be sure your host's firewall accepts incoming connections from + 192.168.7.0/24:* Some of the tests (in particular DNF tests) start an + HTTP server on a random high number port, which is used to serve + files to the target. The DNF module serves + ``${WORKDIR}/oe-rootfs-repo`` so it can run DNF channel commands. + That means your host's firewall must accept incoming connections from + 192.168.7.0/24, which is the default IP range used for tap devices by + ``runqemu``. + +- *Be sure your host has the correct packages installed:* Depending + your host's distribution, you need to have the following packages + installed: + + - Ubuntu and Debian: ``sysstat`` and ``iproute2`` + + - openSUSE: ``sysstat`` and ``iproute2`` + + - Fedora: ``sysstat`` and ``iproute`` + + - CentOS: ``sysstat`` and ``iproute`` + +Once you start running the tests, the following happens: + +#. A copy of the root filesystem is written to ``${WORKDIR}/testimage``. + +#. The image is booted under QEMU using the standard ``runqemu`` script. + +#. A default timeout of 500 seconds occurs to allow for the boot process + to reach the login prompt. You can change the timeout period by + setting + :term:`TEST_QEMUBOOT_TIMEOUT` + in the ``local.conf`` file. + +#. Once the boot process is reached and the login prompt appears, the + tests run. The full boot log is written to + ``${WORKDIR}/testimage/qemu_boot_log``. + +#. Each test module loads in the order found in :term:`TEST_SUITES`. You can + find the full output of the commands run over SSH in + ``${WORKDIR}/testimgage/ssh_target_log``. + +#. If no failures occur, the task running the tests ends successfully. + You can find the output from the ``unittest`` in the task log at + ``${WORKDIR}/temp/log.do_testimage``. + +Enabling Runtime Tests on Hardware +---------------------------------- + +The OpenEmbedded build system can run tests on real hardware, and for +certain devices it can also deploy the image to be tested onto the +device beforehand. + +For automated deployment, a "controller image" is installed onto the +hardware once as part of setup. Then, each time tests are to be run, the +following occurs: + +#. The controller image is booted into and used to write the image to be + tested to a second partition. + +#. The device is then rebooted using an external script that you need to + provide. + +#. The device boots into the image to be tested. + +When running tests (independent of whether the image has been deployed +automatically or not), the device is expected to be connected to a +network on a pre-determined IP address. You can either use static IP +addresses written into the image, or set the image to use DHCP and have +your DHCP server on the test network assign a known IP address based on +the MAC address of the device. + +In order to run tests on hardware, you need to set :term:`TEST_TARGET` to an +appropriate value. For QEMU, you do not have to change anything, the +default value is "qemu". For running tests on hardware, the following +options are available: + +- *"simpleremote":* Choose "simpleremote" if you are going to run tests + on a target system that is already running the image to be tested and + is available on the network. You can use "simpleremote" in + conjunction with either real hardware or an image running within a + separately started QEMU or any other virtual machine manager. + +- *"SystemdbootTarget":* Choose "SystemdbootTarget" if your hardware is + an EFI-based machine with ``systemd-boot`` as bootloader and + ``core-image-testmaster`` (or something similar) is installed. Also, + your hardware under test must be in a DHCP-enabled network that gives + it the same IP address for each reboot. + + If you choose "SystemdbootTarget", there are additional requirements + and considerations. See the + ":ref:`dev-manual/runtime-testing:selecting systemdboottarget`" section, which + follows, for more information. + +- *"BeagleBoneTarget":* Choose "BeagleBoneTarget" if you are deploying + images and running tests on the BeagleBone "Black" or original + "White" hardware. For information on how to use these tests, see the + comments at the top of the BeagleBoneTarget + ``meta-yocto-bsp/lib/oeqa/controllers/beaglebonetarget.py`` file. + +- *"EdgeRouterTarget":* Choose "EdgeRouterTarget" if you are deploying + images and running tests on the Ubiquiti Networks EdgeRouter Lite. + For information on how to use these tests, see the comments at the + top of the EdgeRouterTarget + ``meta-yocto-bsp/lib/oeqa/controllers/edgeroutertarget.py`` file. + +- *"GrubTarget":* Choose "GrubTarget" if you are deploying images and running + tests on any generic PC that boots using GRUB. For information on how + to use these tests, see the comments at the top of the GrubTarget + ``meta-yocto-bsp/lib/oeqa/controllers/grubtarget.py`` file. + +- *"your-target":* Create your own custom target if you want to run + tests when you are deploying images and running tests on a custom + machine within your BSP layer. To do this, you need to add a Python + unit that defines the target class under ``lib/oeqa/controllers/`` + within your layer. You must also provide an empty ``__init__.py``. + For examples, see files in ``meta-yocto-bsp/lib/oeqa/controllers/``. + +Selecting SystemdbootTarget +--------------------------- + +If you did not set :term:`TEST_TARGET` to "SystemdbootTarget", then you do +not need any information in this section. You can skip down to the +":ref:`dev-manual/runtime-testing:running tests`" section. + +If you did set :term:`TEST_TARGET` to "SystemdbootTarget", you also need to +perform a one-time setup of your controller image by doing the following: + +#. *Set EFI_PROVIDER:* Be sure that :term:`EFI_PROVIDER` is as follows:: + + EFI_PROVIDER = "systemd-boot" + +#. *Build the controller image:* Build the ``core-image-testmaster`` image. + The ``core-image-testmaster`` recipe is provided as an example for a + "controller" image and you can customize the image recipe as you would + any other recipe. + + Here are the image recipe requirements: + + - Inherits ``core-image`` so that kernel modules are installed. + + - Installs normal linux utilities not BusyBox ones (e.g. ``bash``, + ``coreutils``, ``tar``, ``gzip``, and ``kmod``). + + - Uses a custom :term:`Initramfs` image with a custom + installer. A normal image that you can install usually creates a + single root filesystem partition. This image uses another installer that + creates a specific partition layout. Not all Board Support + Packages (BSPs) can use an installer. For such cases, you need to + manually create the following partition layout on the target: + + - First partition mounted under ``/boot``, labeled "boot". + + - The main root filesystem partition where this image gets installed, + which is mounted under ``/``. + + - Another partition labeled "testrootfs" where test images get + deployed. + +#. *Install image:* Install the image that you just built on the target + system. + +The final thing you need to do when setting :term:`TEST_TARGET` to +"SystemdbootTarget" is to set up the test image: + +#. *Set up your local.conf file:* Make sure you have the following + statements in your ``local.conf`` file:: + + IMAGE_FSTYPES += "tar.gz" + INHERIT += "testimage" + TEST_TARGET = "SystemdbootTarget" + TEST_TARGET_IP = "192.168.2.3" + +#. *Build your test image:* Use BitBake to build the image:: + + $ bitbake core-image-sato + +Power Control +------------- + +For most hardware targets other than "simpleremote", you can control +power: + +- You can use :term:`TEST_POWERCONTROL_CMD` together with + :term:`TEST_POWERCONTROL_EXTRA_ARGS` as a command that runs on the host + and does power cycling. The test code passes one argument to that + command: off, on or cycle (off then on). Here is an example that + could appear in your ``local.conf`` file:: + + TEST_POWERCONTROL_CMD = "powercontrol.exp test 10.11.12.1 nuc1" + + In this example, the expect + script does the following: + + .. code-block:: shell + + ssh test@10.11.12.1 "pyctl nuc1 arg" + + It then runs a Python script that controls power for a label called + ``nuc1``. + + .. note:: + + You need to customize :term:`TEST_POWERCONTROL_CMD` and + :term:`TEST_POWERCONTROL_EXTRA_ARGS` for your own setup. The one requirement + is that it accepts "on", "off", and "cycle" as the last argument. + +- When no command is defined, it connects to the device over SSH and + uses the classic reboot command to reboot the device. Classic reboot + is fine as long as the machine actually reboots (i.e. the SSH test + has not failed). It is useful for scenarios where you have a simple + setup, typically with a single board, and where some manual + interaction is okay from time to time. + +If you have no hardware to automatically perform power control but still +wish to experiment with automated hardware testing, you can use the +``dialog-power-control`` script that shows a dialog prompting you to perform +the required power action. This script requires either KDialog or Zenity +to be installed. To use this script, set the +:term:`TEST_POWERCONTROL_CMD` +variable as follows:: + + TEST_POWERCONTROL_CMD = "${COREBASE}/scripts/contrib/dialog-power-control" + +Serial Console Connection +------------------------- + +For test target classes requiring a serial console to interact with the +bootloader (e.g. BeagleBoneTarget, EdgeRouterTarget, and GrubTarget), +you need to specify a command to use to connect to the serial console of +the target machine by using the +:term:`TEST_SERIALCONTROL_CMD` +variable and optionally the +:term:`TEST_SERIALCONTROL_EXTRA_ARGS` +variable. + +These cases could be a serial terminal program if the machine is +connected to a local serial port, or a ``telnet`` or ``ssh`` command +connecting to a remote console server. Regardless of the case, the +command simply needs to connect to the serial console and forward that +connection to standard input and output as any normal terminal program +does. For example, to use the picocom terminal program on serial device +``/dev/ttyUSB0`` at 115200bps, you would set the variable as follows:: + + TEST_SERIALCONTROL_CMD = "picocom /dev/ttyUSB0 -b 115200" + +For local +devices where the serial port device disappears when the device reboots, +an additional "serdevtry" wrapper script is provided. To use this +wrapper, simply prefix the terminal command with +``${COREBASE}/scripts/contrib/serdevtry``:: + + TEST_SERIALCONTROL_CMD = "${COREBASE}/scripts/contrib/serdevtry picocom -b 115200 /dev/ttyUSB0" + +Running Tests +============= + +You can start the tests automatically or manually: + +- *Automatically running tests:* To run the tests automatically after the + OpenEmbedded build system successfully creates an image, first set the + :term:`TESTIMAGE_AUTO` variable to "1" in your ``local.conf`` file in the + :term:`Build Directory`:: + + TESTIMAGE_AUTO = "1" + + Next, build your image. If the image successfully builds, the + tests run:: + + bitbake core-image-sato + +- *Manually running tests:* To manually run the tests, first globally + inherit the :ref:`ref-classes-testimage*` class by editing your + ``local.conf`` file:: + + INHERIT += "testimage" + + Next, use BitBake to run the tests:: + + bitbake -c testimage image + +All test files reside in ``meta/lib/oeqa/runtime/cases`` in the +:term:`Source Directory`. A test name maps +directly to a Python module. Each test module may contain a number of +individual tests. Tests are usually grouped together by the area tested +(e.g tests for systemd reside in ``meta/lib/oeqa/runtime/cases/systemd.py``). + +You can add tests to any layer provided you place them in the proper +area and you extend :term:`BBPATH` in +the ``local.conf`` file as normal. Be sure that tests reside in +``layer/lib/oeqa/runtime/cases``. + +.. note:: + + Be sure that module names do not collide with module names used in + the default set of test modules in ``meta/lib/oeqa/runtime/cases``. + +You can change the set of tests run by appending or overriding +:term:`TEST_SUITES` variable in +``local.conf``. Each name in :term:`TEST_SUITES` represents a required test +for the image. Test modules named within :term:`TEST_SUITES` cannot be +skipped even if a test is not suitable for an image (e.g. running the +RPM tests on an image without ``rpm``). Appending "auto" to +:term:`TEST_SUITES` causes the build system to try to run all tests that are +suitable for the image (i.e. each test module may elect to skip itself). + +The order you list tests in :term:`TEST_SUITES` is important and influences +test dependencies. Consequently, tests that depend on other tests should +be added after the test on which they depend. For example, since the +``ssh`` test depends on the ``ping`` test, "ssh" needs to come after +"ping" in the list. The test class provides no re-ordering or dependency +handling. + +.. note:: + + Each module can have multiple classes with multiple test methods. + And, Python ``unittest`` rules apply. + +Here are some things to keep in mind when running tests: + +- The default tests for the image are defined as:: + + DEFAULT_TEST_SUITES:pn-image = "ping ssh df connman syslog xorg scp vnc date rpm dnf dmesg" + +- Add your own test to the list of the by using the following:: + + TEST_SUITES:append = " mytest" + +- Run a specific list of tests as follows:: + + TEST_SUITES = "test1 test2 test3" + + Remember, order is important. Be sure to place a test that is + dependent on another test later in the order. + +Exporting Tests +=============== + +You can export tests so that they can run independently of the build +system. Exporting tests is required if you want to be able to hand the +test execution off to a scheduler. You can only export tests that are +defined in :term:`TEST_SUITES`. + +If your image is already built, make sure the following are set in your +``local.conf`` file:: + + INHERIT += "testexport" + TEST_TARGET_IP = "IP-address-for-the-test-target" + TEST_SERVER_IP = "IP-address-for-the-test-server" + +You can then export the tests with the +following BitBake command form:: + + $ bitbake image -c testexport + +Exporting the tests places them in the :term:`Build Directory` in +``tmp/testexport/``\ image, which is controlled by the :term:`TEST_EXPORT_DIR` +variable. + +You can now run the tests outside of the build environment:: + + $ cd tmp/testexport/image + $ ./runexported.py testdata.json + +Here is a complete example that shows IP addresses and uses the +``core-image-sato`` image:: + + INHERIT += "testexport" + TEST_TARGET_IP = "192.168.7.2" + TEST_SERVER_IP = "192.168.7.1" + +Use BitBake to export the tests:: + + $ bitbake core-image-sato -c testexport + +Run the tests outside of +the build environment using the following:: + + $ cd tmp/testexport/core-image-sato + $ ./runexported.py testdata.json + +Writing New Tests +================= + +As mentioned previously, all new test files need to be in the proper +place for the build system to find them. New tests for additional +functionality outside of the core should be added to the layer that adds +the functionality, in ``layer/lib/oeqa/runtime/cases`` (as long as +:term:`BBPATH` is extended in the +layer's ``layer.conf`` file as normal). Just remember the following: + +- Filenames need to map directly to test (module) names. + +- Do not use module names that collide with existing core tests. + +- Minimally, an empty ``__init__.py`` file must be present in the runtime + directory. + +To create a new test, start by copying an existing module (e.g. +``syslog.py`` or ``gcc.py`` are good ones to use). Test modules can use +code from ``meta/lib/oeqa/utils``, which are helper classes. + +.. note:: + + Structure shell commands such that you rely on them and they return a + single code for success. Be aware that sometimes you will need to + parse the output. See the ``df.py`` and ``date.py`` modules for examples. + +You will notice that all test classes inherit ``oeRuntimeTest``, which +is found in ``meta/lib/oetest.py``. This base class offers some helper +attributes, which are described in the following sections: + +Class Methods +------------- + +Class methods are as follows: + +- *hasPackage(pkg):* Returns "True" if ``pkg`` is in the installed + package list of the image, which is based on the manifest file that + is generated during the :ref:`ref-tasks-rootfs` task. + +- *hasFeature(feature):* Returns "True" if the feature is in + :term:`IMAGE_FEATURES` or + :term:`DISTRO_FEATURES`. + +Class Attributes +---------------- + +Class attributes are as follows: + +- *pscmd:* Equals "ps -ef" if ``procps`` is installed in the image. + Otherwise, ``pscmd`` equals "ps" (busybox). + +- *tc:* The called test context, which gives access to the + following attributes: + + - *d:* The BitBake datastore, which allows you to use stuff such + as ``oeRuntimeTest.tc.d.getVar("VIRTUAL-RUNTIME_init_manager")``. + + - *testslist and testsrequired:* Used internally. The tests + do not need these. + + - *filesdir:* The absolute path to + ``meta/lib/oeqa/runtime/files``, which contains helper files for + tests meant for copying on the target such as small files written + in C for compilation. + + - *target:* The target controller object used to deploy and + start an image on a particular target (e.g. Qemu, SimpleRemote, + and SystemdbootTarget). Tests usually use the following: + + - *ip:* The target's IP address. + + - *server_ip:* The host's IP address, which is usually used + by the DNF test suite. + + - *run(cmd, timeout=None):* The single, most used method. + This command is a wrapper for: ``ssh root@host "cmd"``. The + command returns a tuple: (status, output), which are what their + names imply - the return code of "cmd" and whatever output it + produces. The optional timeout argument represents the number + of seconds the test should wait for "cmd" to return. If the + argument is "None", the test uses the default instance's + timeout period, which is 300 seconds. If the argument is "0", + the test runs until the command returns. + + - *copy_to(localpath, remotepath):* + ``scp localpath root@ip:remotepath``. + + - *copy_from(remotepath, localpath):* + ``scp root@host:remotepath localpath``. + +Instance Attributes +------------------- + +There is a single instance attribute, which is ``target``. The ``target`` +instance attribute is identical to the class attribute of the same name, +which is described in the previous section. This attribute exists as +both an instance and class attribute so tests can use +``self.target.run(cmd)`` in instance methods instead of +``oeRuntimeTest.tc.target.run(cmd)``. + +Installing Packages in the DUT Without the Package Manager +========================================================== + +When a test requires a package built by BitBake, it is possible to +install that package. Installing the package does not require a package +manager be installed in the device under test (DUT). It does, however, +require an SSH connection and the target must be using the +``sshcontrol`` class. + +.. note:: + + This method uses ``scp`` to copy files from the host to the target, which + causes permissions and special attributes to be lost. + +A JSON file is used to define the packages needed by a test. This file +must be in the same path as the file used to define the tests. +Furthermore, the filename must map directly to the test module name with +a ``.json`` extension. + +The JSON file must include an object with the test name as keys of an +object or an array. This object (or array of objects) uses the following +data: + +- "pkg" --- a mandatory string that is the name of the package to be + installed. + +- "rm" --- an optional boolean, which defaults to "false", that specifies + to remove the package after the test. + +- "extract" --- an optional boolean, which defaults to "false", that + specifies if the package must be extracted from the package format. + When set to "true", the package is not automatically installed into + the DUT. + +Following is an example JSON file that handles test "foo" installing +package "bar" and test "foobar" installing packages "foo" and "bar". +Once the test is complete, the packages are removed from the DUT:: + + { + "foo": { + "pkg": "bar" + }, + "foobar": [ + { + "pkg": "foo", + "rm": true + }, + { + "pkg": "bar", + "rm": true + } + ] + } + diff --git a/documentation/dev-manual/sbom.rst b/documentation/dev-manual/sbom.rst new file mode 100644 index 0000000000..448c071c55 --- /dev/null +++ b/documentation/dev-manual/sbom.rst @@ -0,0 +1,72 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Creating a Software Bill of Materials +************************************* + +Once you are able to build an image for your project, once the licenses for +each software component are all identified (see +":ref:`dev-manual/licenses:working with licenses`") and once vulnerability +fixes are applied (see ":ref:`dev-manual/vulnerabilities:checking +for vulnerabilities`"), the OpenEmbedded build system can generate +a description of all the components you used, their licenses, their dependencies, +their sources, the changes that were applied to them and the known +vulnerabilities that were fixed. + +This description is generated in the form of a *Software Bill of Materials* +(:term:`SBOM`), using the :term:`SPDX` standard. + +When you release software, this is the most standard way to provide information +about the Software Supply Chain of your software image and SDK. The +:term:`SBOM` tooling is often used to ensure open source license compliance by +providing the license texts used in the product which legal departments and end +users can read in standardized format. + +:term:`SBOM` information is also critical to performing vulnerability exposure +assessments, as all the components used in the Software Supply Chain are listed. + +The OpenEmbedded build system doesn't generate such information by default. +To make this happen, you must inherit the +:ref:`ref-classes-create-spdx` class from a configuration file:: + + INHERIT += "create-spdx" + +You then get :term:`SPDX` output in JSON format as an +``IMAGE-MACHINE.spdx.json`` file in ``tmp/deploy/images/MACHINE/`` inside the +:term:`Build Directory`. + +This is a toplevel file accompanied by an ``IMAGE-MACHINE.spdx.index.json`` +containing an index of JSON :term:`SPDX` files for individual recipes, together +with an ``IMAGE-MACHINE.spdx.tar.zst`` compressed archive containing all such +files. + +The :ref:`ref-classes-create-spdx` class offers options to include +more information in the output :term:`SPDX` data, such as making the generated +files more human readable (:term:`SPDX_PRETTY`), adding compressed archives of +the files in the generated target packages (:term:`SPDX_ARCHIVE_PACKAGED`), +adding a description of the source files used to generate host tools and target +packages (:term:`SPDX_INCLUDE_SOURCES`) and adding archives of these source +files themselves (:term:`SPDX_ARCHIVE_SOURCES`). + +Though the toplevel :term:`SPDX` output is available in +``tmp/deploy/images/MACHINE/`` inside the :term:`Build Directory`, ancillary +generated files are available in ``tmp/deploy/spdx/MACHINE`` too, such as: + +- The individual :term:`SPDX` JSON files in the ``IMAGE-MACHINE.spdx.tar.zst`` + archive. + +- Compressed archives of the files in the generated target packages, + in ``packages/packagename.tar.zst`` (when :term:`SPDX_ARCHIVE_PACKAGED` + is set). + +- Compressed archives of the source files used to build the host tools + and the target packages in ``recipes/recipe-packagename.tar.zst`` + (when :term:`SPDX_ARCHIVE_SOURCES` is set). Those are needed to fulfill + "source code access" license requirements. + +See the `tools page `__ on the :term:`SPDX` +project website for a list of tools to consume and transform the :term:`SPDX` +data generated by the OpenEmbedded build system. + +See also Joshua Watt's +`Automated SBoM generation with OpenEmbedded and the Yocto Project `__ +presentation at FOSDEM 2023. diff --git a/documentation/dev-manual/securing-images.rst b/documentation/dev-manual/securing-images.rst new file mode 100644 index 0000000000..e5791d3d6d --- /dev/null +++ b/documentation/dev-manual/securing-images.rst @@ -0,0 +1,156 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Making Images More Secure +************************* + +Security is of increasing concern for embedded devices. Consider the +issues and problems discussed in just this sampling of work found across +the Internet: + +- *"*\ `Security Risks of Embedded + Systems `__\ *"* + by Bruce Schneier + +- *"*\ `Internet Census + 2012 `__\ *"* by Carna + Botnet + +- *"*\ `Security Issues for Embedded + Devices `__\ *"* + by Jake Edge + +When securing your image is of concern, there are steps, tools, and +variables that you can consider to help you reach the security goals you +need for your particular device. Not all situations are identical when +it comes to making an image secure. Consequently, this section provides +some guidance and suggestions for consideration when you want to make +your image more secure. + +.. note:: + + Because the security requirements and risks are different for every + type of device, this section cannot provide a complete reference on + securing your custom OS. It is strongly recommended that you also + consult other sources of information on embedded Linux system + hardening and on security. + +General Considerations +====================== + +There are general considerations that help you create more secure images. +You should consider the following suggestions to make your device +more secure: + +- Scan additional code you are adding to the system (e.g. application + code) by using static analysis tools. Look for buffer overflows and + other potential security problems. + +- Pay particular attention to the security for any web-based + administration interface. + + Web interfaces typically need to perform administrative functions and + tend to need to run with elevated privileges. Thus, the consequences + resulting from the interface's security becoming compromised can be + serious. Look for common web vulnerabilities such as + cross-site-scripting (XSS), unvalidated inputs, and so forth. + + As with system passwords, the default credentials for accessing a + web-based interface should not be the same across all devices. This + is particularly true if the interface is enabled by default as it can + be assumed that many end-users will not change the credentials. + +- Ensure you can update the software on the device to mitigate + vulnerabilities discovered in the future. This consideration + especially applies when your device is network-enabled. + +- Regularly scan and apply fixes for CVE security issues affecting + all software components in the product, see ":ref:`dev-manual/vulnerabilities:checking for vulnerabilities`". + +- Regularly update your version of Poky and OE-Core from their upstream + developers, e.g. to apply updates and security fixes from stable + and :term:`LTS` branches. + +- Ensure you remove or disable debugging functionality before producing + the final image. For information on how to do this, see the + ":ref:`dev-manual/securing-images:considerations specific to the openembedded build system`" + section. + +- Ensure you have no network services listening that are not needed. + +- Remove any software from the image that is not needed. + +- Enable hardware support for secure boot functionality when your + device supports this functionality. + +Security Flags +============== + +The Yocto Project has security flags that you can enable that help make +your build output more secure. The security flags are in the +``meta/conf/distro/include/security_flags.inc`` file in your +:term:`Source Directory` (e.g. ``poky``). + +.. note:: + + Depending on the recipe, certain security flags are enabled and + disabled by default. + +Use the following line in your ``local.conf`` file or in your custom +distribution configuration file to enable the security compiler and +linker flags for your build:: + + require conf/distro/include/security_flags.inc + +Considerations Specific to the OpenEmbedded Build System +======================================================== + +You can take some steps that are specific to the OpenEmbedded build +system to make your images more secure: + +- Ensure "debug-tweaks" is not one of your selected + :term:`IMAGE_FEATURES`. + When creating a new project, the default is to provide you with an + initial ``local.conf`` file that enables this feature using the + :term:`EXTRA_IMAGE_FEATURES` + variable with the line:: + + EXTRA_IMAGE_FEATURES = "debug-tweaks" + + To disable that feature, simply comment out that line in your + ``local.conf`` file, or make sure :term:`IMAGE_FEATURES` does not contain + "debug-tweaks" before producing your final image. Among other things, + leaving this in place sets the root password as blank, which makes + logging in for debugging or inspection easy during development but + also means anyone can easily log in during production. + +- It is possible to set a root password for the image and also to set + passwords for any extra users you might add (e.g. administrative or + service type users). When you set up passwords for multiple images or + users, you should not duplicate passwords. + + To set up passwords, use the :ref:`ref-classes-extrausers` class, which + is the preferred method. For an example on how to set up both root and + user passwords, see the ":ref:`ref-classes-extrausers`" section. + + .. note:: + + When adding extra user accounts or setting a root password, be + cautious about setting the same password on every device. If you + do this, and the password you have set is exposed, then every + device is now potentially compromised. If you need this access but + want to ensure security, consider setting a different, random + password for each device. Typically, you do this as a separate + step after you deploy the image onto the device. + +- Consider enabling a Mandatory Access Control (MAC) framework such as + SMACK or SELinux and tuning it appropriately for your device's usage. + You can find more information in the + :yocto_git:`meta-selinux ` layer. + +Tools for Hardening Your Image +============================== + +The Yocto Project provides tools for making your image more secure. You +can find these tools in the ``meta-security`` layer of the +:yocto_git:`Yocto Project Source Repositories <>`. + diff --git a/documentation/dev-manual/speeding-up-build.rst b/documentation/dev-manual/speeding-up-build.rst new file mode 100644 index 0000000000..31b6f75ab0 --- /dev/null +++ b/documentation/dev-manual/speeding-up-build.rst @@ -0,0 +1,109 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Speeding Up a Build +******************* + +Build time can be an issue. By default, the build system uses simple +controls to try and maximize build efficiency. In general, the default +settings for all the following variables result in the most efficient +build times when dealing with single socket systems (i.e. a single CPU). +If you have multiple CPUs, you might try increasing the default values +to gain more speed. See the descriptions in the glossary for each +variable for more information: + +- :term:`BB_NUMBER_THREADS`: + The maximum number of threads BitBake simultaneously executes. + +- :term:`BB_NUMBER_PARSE_THREADS`: + The number of threads BitBake uses during parsing. + +- :term:`PARALLEL_MAKE`: Extra + options passed to the ``make`` command during the + :ref:`ref-tasks-compile` task in + order to specify parallel compilation on the local build host. + +- :term:`PARALLEL_MAKEINST`: + Extra options passed to the ``make`` command during the + :ref:`ref-tasks-install` task in + order to specify parallel installation on the local build host. + +As mentioned, these variables all scale to the number of processor cores +available on the build system. For single socket systems, this +auto-scaling ensures that the build system fundamentally takes advantage +of potential parallel operations during the build based on the build +machine's capabilities. + +Following are additional factors that can affect build speed: + +- File system type: The file system type that the build is being + performed on can also influence performance. Using ``ext4`` is + recommended as compared to ``ext2`` and ``ext3`` due to ``ext4`` + improved features such as extents. + +- Disabling the updating of access time using ``noatime``: The + ``noatime`` mount option prevents the build system from updating file + and directory access times. + +- Setting a longer commit: Using the "commit=" mount option increases + the interval in seconds between disk cache writes. Changing this + interval from the five second default to something longer increases + the risk of data loss but decreases the need to write to the disk, + thus increasing the build performance. + +- Choosing the packaging backend: Of the available packaging backends, + IPK is the fastest. Additionally, selecting a singular packaging + backend also helps. + +- Using ``tmpfs`` for :term:`TMPDIR` + as a temporary file system: While this can help speed up the build, + the benefits are limited due to the compiler using ``-pipe``. The + build system goes to some lengths to avoid ``sync()`` calls into the + file system on the principle that if there was a significant failure, + the :term:`Build Directory` contents could easily be rebuilt. + +- Inheriting the :ref:`ref-classes-rm-work` class: + Inheriting this class has shown to speed up builds due to + significantly lower amounts of data stored in the data cache as well + as on disk. Inheriting this class also makes cleanup of + :term:`TMPDIR` faster, at the + expense of being easily able to dive into the source code. File + system maintainers have recommended that the fastest way to clean up + large numbers of files is to reformat partitions rather than delete + files due to the linear nature of partitions. This, of course, + assumes you structure the disk partitions and file systems in a way + that this is practical. + +Aside from the previous list, you should keep some trade offs in mind +that can help you speed up the build: + +- Remove items from + :term:`DISTRO_FEATURES` + that you might not need. + +- Exclude debug symbols and other debug information: If you do not need + these symbols and other debug information, disabling the ``*-dbg`` + package generation can speed up the build. You can disable this + generation by setting the + :term:`INHIBIT_PACKAGE_DEBUG_SPLIT` + variable to "1". + +- Disable static library generation for recipes derived from + ``autoconf`` or ``libtool``: Following is an example showing how to + disable static libraries and still provide an override to handle + exceptions:: + + STATICLIBCONF = "--disable-static" + STATICLIBCONF:sqlite3-native = "" + EXTRA_OECONF += "${STATICLIBCONF}" + + .. note:: + + - Some recipes need static libraries in order to work correctly + (e.g. ``pseudo-native`` needs ``sqlite3-native``). Overrides, + as in the previous example, account for these kinds of + exceptions. + + - Some packages have packaging code that assumes the presence of + the static libraries. If so, you might need to exclude them as + well. + diff --git a/documentation/dev-manual/temporary-source-code.rst b/documentation/dev-manual/temporary-source-code.rst new file mode 100644 index 0000000000..08bf68d982 --- /dev/null +++ b/documentation/dev-manual/temporary-source-code.rst @@ -0,0 +1,66 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Finding Temporary Source Code +***************************** + +You might find it helpful during development to modify the temporary +source code used by recipes to build packages. For example, suppose you +are developing a patch and you need to experiment a bit to figure out +your solution. After you have initially built the package, you can +iteratively tweak the source code, which is located in the +:term:`Build Directory`, and then you can force a re-compile and quickly +test your altered code. Once you settle on a solution, you can then preserve +your changes in the form of patches. + +During a build, the unpacked temporary source code used by recipes to +build packages is available in the :term:`Build Directory` as defined by the +:term:`S` variable. Below is the default value for the :term:`S` variable as +defined in the ``meta/conf/bitbake.conf`` configuration file in the +:term:`Source Directory`:: + + S = "${WORKDIR}/${BP}" + +You should be aware that many recipes override the +:term:`S` variable. For example, recipes that fetch their source from Git +usually set :term:`S` to ``${WORKDIR}/git``. + +.. note:: + + The :term:`BP` represents the base recipe name, which consists of the name + and version:: + + BP = "${BPN}-${PV}" + + +The path to the work directory for the recipe +(:term:`WORKDIR`) is defined as +follows:: + + ${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR} + +The actual directory depends on several things: + +- :term:`TMPDIR`: The top-level build + output directory. + +- :term:`MULTIMACH_TARGET_SYS`: + The target system identifier. + +- :term:`PN`: The recipe name. + +- :term:`EXTENDPE`: The epoch --- if + :term:`PE` is not specified, which is + usually the case for most recipes, then :term:`EXTENDPE` is blank. + +- :term:`PV`: The recipe version. + +- :term:`PR`: The recipe revision. + +As an example, assume a Source Directory top-level folder named +``poky``, a default :term:`Build Directory` at ``poky/build``, and a +``qemux86-poky-linux`` machine target system. Furthermore, suppose your +recipe is named ``foo_1.3.0.bb``. In this case, the work directory the +build system uses to build the package would be as follows:: + + poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0 + diff --git a/documentation/dev-manual/upgrading-recipes.rst b/documentation/dev-manual/upgrading-recipes.rst new file mode 100644 index 0000000000..abcf7ca9fe --- /dev/null +++ b/documentation/dev-manual/upgrading-recipes.rst @@ -0,0 +1,397 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Upgrading Recipes +***************** + +Over time, upstream developers publish new versions for software built +by layer recipes. It is recommended to keep recipes up-to-date with +upstream version releases. + +While there are several methods to upgrade a recipe, you might +consider checking on the upgrade status of a recipe first. You can do so +using the ``devtool check-upgrade-status`` command. See the +":ref:`devtool-checking-on-the-upgrade-status-of-a-recipe`" +section in the Yocto Project Reference Manual for more information. + +The remainder of this section describes three ways you can upgrade a +recipe. You can use the Automated Upgrade Helper (AUH) to set up +automatic version upgrades. Alternatively, you can use +``devtool upgrade`` to set up semi-automatic version upgrades. Finally, +you can manually upgrade a recipe by editing the recipe itself. + +Using the Auto Upgrade Helper (AUH) +=================================== + +The AUH utility works in conjunction with the OpenEmbedded build system +in order to automatically generate upgrades for recipes based on new +versions being published upstream. Use AUH when you want to create a +service that performs the upgrades automatically and optionally sends +you an email with the results. + +AUH allows you to update several recipes with a single use. You can also +optionally perform build and integration tests using images with the +results saved to your hard drive and emails of results optionally sent +to recipe maintainers. Finally, AUH creates Git commits with appropriate +commit messages in the layer's tree for the changes made to recipes. + +.. note:: + + In some conditions, you should not use AUH to upgrade recipes + and should instead use either ``devtool upgrade`` or upgrade your + recipes manually: + + - When AUH cannot complete the upgrade sequence. This situation + usually results because custom patches carried by the recipe + cannot be automatically rebased to the new version. In this case, + ``devtool upgrade`` allows you to manually resolve conflicts. + + - When for any reason you want fuller control over the upgrade + process. For example, when you want special arrangements for + testing. + +The following steps describe how to set up the AUH utility: + +#. *Be Sure the Development Host is Set Up:* You need to be sure that + your development host is set up to use the Yocto Project. For + information on how to set up your host, see the + ":ref:`dev-manual/start:Preparing the Build Host`" section. + +#. *Make Sure Git is Configured:* The AUH utility requires Git to be + configured because AUH uses Git to save upgrades. Thus, you must have + Git user and email configured. The following command shows your + configurations:: + + $ git config --list + + If you do not have the user and + email configured, you can use the following commands to do so:: + + $ git config --global user.name some_name + $ git config --global user.email username@domain.com + +#. *Clone the AUH Repository:* To use AUH, you must clone the repository + onto your development host. The following command uses Git to create + a local copy of the repository on your system:: + + $ git clone git://git.yoctoproject.org/auto-upgrade-helper + Cloning into 'auto-upgrade-helper'... remote: Counting objects: 768, done. + remote: Compressing objects: 100% (300/300), done. + remote: Total 768 (delta 499), reused 703 (delta 434) + Receiving objects: 100% (768/768), 191.47 KiB | 98.00 KiB/s, done. + Resolving deltas: 100% (499/499), done. + Checking connectivity... done. + + AUH is not part of the :term:`OpenEmbedded-Core (OE-Core)` or + :term:`Poky` repositories. + +#. *Create a Dedicated Build Directory:* Run the :ref:`structure-core-script` + script to create a fresh :term:`Build Directory` that you use exclusively + for running the AUH utility:: + + $ cd poky + $ source oe-init-build-env your_AUH_build_directory + + Re-using an existing :term:`Build Directory` and its configurations is not + recommended as existing settings could cause AUH to fail or behave + undesirably. + +#. *Make Configurations in Your Local Configuration File:* Several + settings are needed in the ``local.conf`` file in the build + directory you just created for AUH. Make these following + configurations: + + - If you want to enable :ref:`Build + History `, + which is optional, you need the following lines in the + ``conf/local.conf`` file:: + + INHERIT =+ "buildhistory" + BUILDHISTORY_COMMIT = "1" + + With this configuration and a successful + upgrade, a build history "diff" file appears in the + ``upgrade-helper/work/recipe/buildhistory-diff.txt`` file found in + your :term:`Build Directory`. + + - If you want to enable testing through the :ref:`ref-classes-testimage*` + class, which is optional, you need to have the following set in + your ``conf/local.conf`` file:: + + INHERIT += "testimage" + + .. note:: + + If your distro does not enable by default ptest, which Poky + does, you need the following in your ``local.conf`` file:: + + DISTRO_FEATURES:append = " ptest" + + +#. *Optionally Start a vncserver:* If you are running in a server + without an X11 session, you need to start a vncserver:: + + $ vncserver :1 + $ export DISPLAY=:1 + +#. *Create and Edit an AUH Configuration File:* You need to have the + ``upgrade-helper/upgrade-helper.conf`` configuration file in your + :term:`Build Directory`. You can find a sample configuration file in the + :yocto_git:`AUH source repository `. + + Read through the sample file and make configurations as needed. For + example, if you enabled build history in your ``local.conf`` as + described earlier, you must enable it in ``upgrade-helper.conf``. + + Also, if you are using the default ``maintainers.inc`` file supplied + with Poky and located in ``meta-yocto`` and you do not set a + "maintainers_whitelist" or "global_maintainer_override" in the + ``upgrade-helper.conf`` configuration, and you specify "-e all" on + the AUH command-line, the utility automatically sends out emails to + all the default maintainers. Please avoid this. + +This next set of examples describes how to use the AUH: + +- *Upgrading a Specific Recipe:* To upgrade a specific recipe, use the + following form:: + + $ upgrade-helper.py recipe_name + + For example, this command upgrades the ``xmodmap`` recipe:: + + $ upgrade-helper.py xmodmap + +- *Upgrading a Specific Recipe to a Particular Version:* To upgrade a + specific recipe to a particular version, use the following form:: + + $ upgrade-helper.py recipe_name -t version + + For example, this command upgrades the ``xmodmap`` recipe to version 1.2.3:: + + $ upgrade-helper.py xmodmap -t 1.2.3 + +- *Upgrading all Recipes to the Latest Versions and Suppressing Email + Notifications:* To upgrade all recipes to their most recent versions + and suppress the email notifications, use the following command:: + + $ upgrade-helper.py all + +- *Upgrading all Recipes to the Latest Versions and Send Email + Notifications:* To upgrade all recipes to their most recent versions + and send email messages to maintainers for each attempted recipe as + well as a status email, use the following command:: + + $ upgrade-helper.py -e all + +Once you have run the AUH utility, you can find the results in the AUH +:term:`Build Directory`:: + + ${BUILDDIR}/upgrade-helper/timestamp + +The AUH utility +also creates recipe update commits from successful upgrade attempts in +the layer tree. + +You can easily set up to run the AUH utility on a regular basis by using +a cron job. See the +:yocto_git:`weeklyjob.sh ` +file distributed with the utility for an example. + +Using ``devtool upgrade`` +========================= + +As mentioned earlier, an alternative method for upgrading recipes to +newer versions is to use +:doc:`devtool upgrade `. +You can read about ``devtool upgrade`` in general in the +":ref:`sdk-manual/extensible:use \`\`devtool upgrade\`\` to create a version of the recipe that supports a newer version of the software`" +section in the Yocto Project Application Development and the Extensible +Software Development Kit (eSDK) Manual. + +To see all the command-line options available with ``devtool upgrade``, +use the following help command:: + + $ devtool upgrade -h + +If you want to find out what version a recipe is currently at upstream +without any attempt to upgrade your local version of the recipe, you can +use the following command:: + + $ devtool latest-version recipe_name + +As mentioned in the previous section describing AUH, ``devtool upgrade`` +works in a less-automated manner than AUH. Specifically, +``devtool upgrade`` only works on a single recipe that you name on the +command line, cannot perform build and integration testing using images, +and does not automatically generate commits for changes in the source +tree. Despite all these "limitations", ``devtool upgrade`` updates the +recipe file to the new upstream version and attempts to rebase custom +patches contained by the recipe as needed. + +.. note:: + + AUH uses much of ``devtool upgrade`` behind the scenes making AUH somewhat + of a "wrapper" application for ``devtool upgrade``. + +A typical scenario involves having used Git to clone an upstream +repository that you use during build operations. Because you have built the +recipe in the past, the layer is likely added to your +configuration already. If for some reason, the layer is not added, you +could add it easily using the +":ref:`bitbake-layers `" +script. For example, suppose you use the ``nano.bb`` recipe from the +``meta-oe`` layer in the ``meta-openembedded`` repository. For this +example, assume that the layer has been cloned into following area:: + + /home/scottrif/meta-openembedded + +The following command from your :term:`Build Directory` adds the layer to +your build configuration (i.e. ``${BUILDDIR}/conf/bblayers.conf``):: + + $ bitbake-layers add-layer /home/scottrif/meta-openembedded/meta-oe + NOTE: Starting bitbake server... + Parsing recipes: 100% |##########################################| Time: 0:00:55 + Parsing of 1431 .bb files complete (0 cached, 1431 parsed). 2040 targets, 56 skipped, 0 masked, 0 errors. + Removing 12 recipes from the x86_64 sysroot: 100% |##############| Time: 0:00:00 + Removing 1 recipes from the x86_64_i586 sysroot: 100% |##########| Time: 0:00:00 + Removing 5 recipes from the i586 sysroot: 100% |#################| Time: 0:00:00 + Removing 5 recipes from the qemux86 sysroot: 100% |##############| Time: 0:00:00 + +For this example, assume that the ``nano.bb`` recipe that +is upstream has a 2.9.3 version number. However, the version in the +local repository is 2.7.4. The following command from your build +directory automatically upgrades the recipe for you:: + + $ devtool upgrade nano -V 2.9.3 + NOTE: Starting bitbake server... + NOTE: Creating workspace layer in /home/scottrif/poky/build/workspace + Parsing recipes: 100% |##########################################| Time: 0:00:46 + Parsing of 1431 .bb files complete (0 cached, 1431 parsed). 2040 targets, 56 skipped, 0 masked, 0 errors. + NOTE: Extracting current version source... + NOTE: Resolving any missing task queue dependencies + . + . + . + NOTE: Executing SetScene Tasks + NOTE: Executing RunQueue Tasks + NOTE: Tasks Summary: Attempted 74 tasks of which 72 didn't need to be rerun and all succeeded. + Adding changed files: 100% |#####################################| Time: 0:00:00 + NOTE: Upgraded source extracted to /home/scottrif/poky/build/workspace/sources/nano + NOTE: New recipe is /home/scottrif/poky/build/workspace/recipes/nano/nano_2.9.3.bb + +.. note:: + + Using the ``-V`` option is not necessary. Omitting the version number causes + ``devtool upgrade`` to upgrade the recipe to the most recent version. + +Continuing with this example, you can use ``devtool build`` to build the +newly upgraded recipe:: + + $ devtool build nano + NOTE: Starting bitbake server... + Loading cache: 100% |################################################################################################| Time: 0:00:01 + Loaded 2040 entries from dependency cache. + Parsing recipes: 100% |##############################################################################################| Time: 0:00:00 + Parsing of 1432 .bb files complete (1431 cached, 1 parsed). 2041 targets, 56 skipped, 0 masked, 0 errors. + NOTE: Resolving any missing task queue dependencies + . + . + . + NOTE: Executing SetScene Tasks + NOTE: Executing RunQueue Tasks + NOTE: nano: compiling from external source tree /home/scottrif/poky/build/workspace/sources/nano + NOTE: Tasks Summary: Attempted 520 tasks of which 304 didn't need to be rerun and all succeeded. + +Within the ``devtool upgrade`` workflow, you can +deploy and test your rebuilt software. For this example, +however, running ``devtool finish`` cleans up the workspace once the +source in your workspace is clean. This usually means using Git to stage +and submit commits for the changes generated by the upgrade process. + +Once the tree is clean, you can clean things up in this example with the +following command from the ``${BUILDDIR}/workspace/sources/nano`` +directory:: + + $ devtool finish nano meta-oe + NOTE: Starting bitbake server... + Loading cache: 100% |################################################################################################| Time: 0:00:00 + Loaded 2040 entries from dependency cache. + Parsing recipes: 100% |##############################################################################################| Time: 0:00:01 + Parsing of 1432 .bb files complete (1431 cached, 1 parsed). 2041 targets, 56 skipped, 0 masked, 0 errors. + NOTE: Adding new patch 0001-nano.bb-Stuff-I-changed-when-upgrading-nano.bb.patch + NOTE: Updating recipe nano_2.9.3.bb + NOTE: Removing file /home/scottrif/meta-openembedded/meta-oe/recipes-support/nano/nano_2.7.4.bb + NOTE: Moving recipe file to /home/scottrif/meta-openembedded/meta-oe/recipes-support/nano + NOTE: Leaving source tree /home/scottrif/poky/build/workspace/sources/nano as-is; if you no longer need it then please delete it manually + + +Using the ``devtool finish`` command cleans up the workspace and creates a patch +file based on your commits. The tool puts all patch files back into the +source directory in a sub-directory named ``nano`` in this case. + +Manually Upgrading a Recipe +=========================== + +If for some reason you choose not to upgrade recipes using +:ref:`dev-manual/upgrading-recipes:Using the Auto Upgrade Helper (AUH)` or +by :ref:`dev-manual/upgrading-recipes:Using \`\`devtool upgrade\`\``, +you can manually edit the recipe files to upgrade the versions. + +.. note:: + + Manually updating multiple recipes scales poorly and involves many + steps. The recommendation to upgrade recipe versions is through AUH + or ``devtool upgrade``, both of which automate some steps and provide + guidance for others needed for the manual process. + +To manually upgrade recipe versions, follow these general steps: + +#. *Change the Version:* Rename the recipe such that the version (i.e. + the :term:`PV` part of the recipe name) + changes appropriately. If the version is not part of the recipe name, + change the value as it is set for :term:`PV` within the recipe itself. + +#. *Update* :term:`SRCREV` *if Needed*: If the source code your recipe builds + is fetched from Git or some other version control system, update + :term:`SRCREV` to point to the + commit hash that matches the new version. + +#. *Build the Software:* Try to build the recipe using BitBake. Typical + build failures include the following: + + - License statements were updated for the new version. For this + case, you need to review any changes to the license and update the + values of :term:`LICENSE` and + :term:`LIC_FILES_CHKSUM` + as needed. + + .. note:: + + License changes are often inconsequential. For example, the + license text's copyright year might have changed. + + - Custom patches carried by the older version of the recipe might + fail to apply to the new version. For these cases, you need to + review the failures. Patches might not be necessary for the new + version of the software if the upgraded version has fixed those + issues. If a patch is necessary and failing, you need to rebase it + into the new version. + +#. *Optionally Attempt to Build for Several Architectures:* Once you + successfully build the new software for a given architecture, you + could test the build for other architectures by changing the + :term:`MACHINE` variable and + rebuilding the software. This optional step is especially important + if the recipe is to be released publicly. + +#. *Check the Upstream Change Log or Release Notes:* Checking both these + reveals if there are new features that could break + backwards-compatibility. If so, you need to take steps to mitigate or + eliminate that situation. + +#. *Optionally Create a Bootable Image and Test:* If you want, you can + test the new software by booting it onto actual hardware. + +#. *Create a Commit with the Change in the Layer Repository:* After all + builds work and any testing is successful, you can create commits for + any changes in the layer holding your upgraded recipe. + diff --git a/documentation/dev-manual/vulnerabilities.rst b/documentation/dev-manual/vulnerabilities.rst new file mode 100644 index 0000000000..ac0ca249c1 --- /dev/null +++ b/documentation/dev-manual/vulnerabilities.rst @@ -0,0 +1,214 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Checking for Vulnerabilities +**************************** + +Vulnerabilities in Poky and OE-Core +=================================== + +The Yocto Project has an infrastructure to track and address unfixed +known security vulnerabilities, as tracked by the public +:wikipedia:`Common Vulnerabilities and Exposures (CVE) ` +database. + +The Yocto Project maintains a `list of known vulnerabilities +`__ +for packages in Poky and OE-Core, tracking the evolution of the number of +unpatched CVEs and the status of patches. Such information is available for +the current development version and for each supported release. + +Security is a process, not a product, and thus at any time, a number of security +issues may be impacting Poky and OE-Core. It is up to the maintainers, users, +contributors and anyone interested in the issues to investigate and possibly fix them by +updating software components to newer versions or by applying patches to address them. +It is recommended to work with Poky and OE-Core upstream maintainers and submit +patches to fix them, see ":doc:`../contributor-guide/submit-changes`" for details. + +Vulnerability check at build time +================================= + +To enable a check for CVE security vulnerabilities using +:ref:`ref-classes-cve-check` in the specific image or target you are building, +add the following setting to your configuration:: + + INHERIT += "cve-check" + +The CVE database contains some old incomplete entries which have been +deemed not to impact Poky or OE-Core. These CVE entries can be excluded from the +check using build configuration:: + + include conf/distro/include/cve-extra-exclusions.inc + +With this CVE check enabled, BitBake build will try to map each compiled software component +recipe name and version information to the CVE database and generate recipe and +image specific reports. These reports will contain: + +- metadata about the software component like names and versions + +- metadata about the CVE issue such as description and NVD link + +- for each software component, a list of CVEs which are possibly impacting this version + +- status of each CVE: ``Patched``, ``Unpatched`` or ``Ignored`` + +The status ``Patched`` means that a patch file to address the security issue has been +applied. ``Unpatched`` status means that no patches to address the issue have been +applied and that the issue needs to be investigated. ``Ignored`` means that after +analysis, it has been deemed to ignore the issue as it for example affects +the software component on a different operating system platform. + +After a build with CVE check enabled, reports for each compiled source recipe will be +found in ``build/tmp/deploy/cve``. + +For example the CVE check report for the ``flex-native`` recipe looks like:: + + $ cat poky/build/tmp/deploy/cve/flex-native + LAYER: meta + PACKAGE NAME: flex-native + PACKAGE VERSION: 2.6.4 + CVE: CVE-2016-6354 + CVE STATUS: Patched + CVE SUMMARY: Heap-based buffer overflow in the yy_get_next_buffer function in Flex before 2.6.1 might allow context-dependent attackers to cause a denial of service or possibly execute arbitrary code via vectors involving num_to_read. + CVSS v2 BASE SCORE: 7.5 + CVSS v3 BASE SCORE: 9.8 + VECTOR: NETWORK + MORE INFORMATION: https://nvd.nist.gov/vuln/detail/CVE-2016-6354 + + LAYER: meta + PACKAGE NAME: flex-native + PACKAGE VERSION: 2.6.4 + CVE: CVE-2019-6293 + CVE STATUS: Ignored + CVE SUMMARY: An issue was discovered in the function mark_beginning_as_normal in nfa.c in flex 2.6.4. There is a stack exhaustion problem caused by the mark_beginning_as_normal function making recursive calls to itself in certain scenarios involving lots of '*' characters. Remote attackers could leverage this vulnerability to cause a denial-of-service. + CVSS v2 BASE SCORE: 4.3 + CVSS v3 BASE SCORE: 5.5 + VECTOR: NETWORK + MORE INFORMATION: https://nvd.nist.gov/vuln/detail/CVE-2019-6293 + +For images, a summary of all recipes included in the image and their CVEs is also +generated in textual and JSON formats. These ``.cve`` and ``.json`` reports can be found +in the ``tmp/deploy/images`` directory for each compiled image. + +At build time CVE check will also throw warnings about ``Unpatched`` CVEs:: + + WARNING: flex-2.6.4-r0 do_cve_check: Found unpatched CVE (CVE-2019-6293), for more information check /poky/build/tmp/work/core2-64-poky-linux/flex/2.6.4-r0/temp/cve.log + WARNING: libarchive-3.5.1-r0 do_cve_check: Found unpatched CVE (CVE-2021-36976), for more information check /poky/build/tmp/work/core2-64-poky-linux/libarchive/3.5.1-r0/temp/cve.log + +It is also possible to check the CVE status of individual packages as follows:: + + bitbake -c cve_check flex libarchive + +Fixing CVE product name and version mappings +============================================ + +By default, :ref:`ref-classes-cve-check` uses the recipe name :term:`BPN` as CVE +product name when querying the CVE database. If this mapping contains false positives, e.g. +some reported CVEs are not for the software component in question, or false negatives like +some CVEs are not found to impact the recipe when they should, then the problems can be +in the recipe name to CVE product mapping. These mapping issues can be fixed by setting +the :term:`CVE_PRODUCT` variable inside the recipe. This defines the name of the software component in the +upstream `NIST CVE database `__. + +The variable supports using vendor and product names like this:: + + CVE_PRODUCT = "flex_project:flex" + +In this example the vendor name used in the CVE database is ``flex_project`` and the +product is ``flex``. With this setting the ``flex`` recipe only maps to this specific +product and not products from other vendors with same name ``flex``. + +Similarly, when the recipe version :term:`PV` is not compatible with software versions used by +the upstream software component releases and the CVE database, these can be fixed using +the :term:`CVE_VERSION` variable. + +Note that if the CVE entries in the NVD database contain bugs or have missing or incomplete +information, it is recommended to fix the information there directly instead of working +around the issues possibly for a long time in Poky and OE-Core side recipes. Feedback to +NVD about CVE entries can be provided through the `NVD contact form `__. + +Fixing vulnerabilities in recipes +================================= + +If a CVE security issue impacts a software component, it can be fixed by updating to a newer +version of the software component or by applying a patch. For Poky and OE-Core master branches, updating +to a newer software component release with fixes is the best option, but patches can be applied +if releases are not yet available. + +For stable branches, it is preferred to apply patches for the issues. For some software +components minor version updates can also be applied if they are backwards compatible. + +Here is an example of fixing CVE security issues with patch files, +an example from the :oe_layerindex:`ffmpeg recipe`:: + + SRC_URI = "https://www.ffmpeg.org/releases/${BP}.tar.xz \ + file://0001-libavutil-include-assembly-with-full-path-from-sourc.patch \ + file://fix-CVE-2020-20446.patch \ + file://fix-CVE-2020-20453.patch \ + file://fix-CVE-2020-22015.patch \ + file://fix-CVE-2020-22021.patch \ + file://fix-CVE-2020-22033-CVE-2020-22019.patch \ + file://fix-CVE-2021-33815.patch \ + +A good practice is to include the CVE identifier in both the patch file name +and inside the patch file commit message using the format:: + + CVE: CVE-2020-22033 + +CVE checker will then capture this information and change the CVE status to ``Patched`` +in the generated reports. + +If analysis shows that the CVE issue does not impact the recipe due to configuration, platform, +version or other reasons, the CVE can be marked as ``Ignored`` using the :term:`CVE_CHECK_IGNORE` variable. +As mentioned previously, if data in the CVE database is wrong, it is recommend to fix those +issues in the CVE database directly. + +Recipes can be completely skipped by CVE check by including the recipe name in +the :term:`CVE_CHECK_SKIP_RECIPE` variable. + +Implementation details +====================== + +Here's what the :ref:`ref-classes-cve-check` class does to find unpatched CVE IDs. + +First the code goes through each patch file provided by a recipe. If a valid CVE ID +is found in the name of the file, the corresponding CVE is considered as patched. +Don't forget that if multiple CVE IDs are found in the filename, only the last +one is considered. Then, the code looks for ``CVE: CVE-ID`` lines in the patch +file. The found CVE IDs are also considered as patched. + +Then, the code looks up all the CVE IDs in the NIST database for all the +products defined in :term:`CVE_PRODUCT`. Then, for each found CVE: + +- If the package name (:term:`PN`) is part of + :term:`CVE_CHECK_SKIP_RECIPE`, it is considered as ``Patched``. + +- If the CVE ID is part of :term:`CVE_CHECK_IGNORE`, it is + set as ``Ignored``. + +- If the CVE ID is part of the patched CVE for the recipe, it is + already considered as ``Patched``. + +- Otherwise, the code checks whether the recipe version (:term:`PV`) + is within the range of versions impacted by the CVE. If so, the CVE + is considered as ``Unpatched``. + +The CVE database is stored in :term:`DL_DIR` and can be inspected using +``sqlite3`` command as follows:: + + sqlite3 downloads/CVE_CHECK/nvdcve_1.1.db .dump | grep CVE-2021-37462 + +When analyzing CVEs, it is recommended to: + +- study the latest information in `CVE database `__. + +- check how upstream developers of the software component addressed the issue, e.g. + what patch was applied, which upstream release contains the fix. + +- check what other Linux distributions like `Debian `__ + did to analyze and address the issue. + +- follow security notices from other Linux distributions. + +- follow public `open source security mailing lists `__ for + discussions and advance notifications of CVE bugs and software releases with fixes. + diff --git a/documentation/dev-manual/wayland.rst b/documentation/dev-manual/wayland.rst new file mode 100644 index 0000000000..097be9cbde --- /dev/null +++ b/documentation/dev-manual/wayland.rst @@ -0,0 +1,90 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Using Wayland and Weston +************************ + +:wikipedia:`Wayland ` +is a computer display server protocol that provides a method for +compositing window managers to communicate directly with applications +and video hardware and expects them to communicate with input hardware +using other libraries. Using Wayland with supporting targets can result +in better control over graphics frame rendering than an application +might otherwise achieve. + +The Yocto Project provides the Wayland protocol libraries and the +reference :wikipedia:`Weston ` +compositor as part of its release. You can find the integrated packages +in the ``meta`` layer of the :term:`Source Directory`. +Specifically, you +can find the recipes that build both Wayland and Weston at +``meta/recipes-graphics/wayland``. + +You can build both the Wayland and Weston packages for use only with targets +that accept the :wikipedia:`Mesa 3D and Direct Rendering Infrastructure +`, which is also known as Mesa DRI. This implies that +you cannot build and use the packages if your target uses, for example, the +Intel Embedded Media and Graphics Driver (Intel EMGD) that overrides Mesa DRI. + +.. note:: + + Due to lack of EGL support, Weston 1.0.3 will not run directly on the + emulated QEMU hardware. However, this version of Weston will run + under X emulation without issues. + +This section describes what you need to do to implement Wayland and use +the Weston compositor when building an image for a supporting target. + +Enabling Wayland in an Image +============================ + +To enable Wayland, you need to enable it to be built and enable it to be +included (installed) in the image. + +Building Wayland +---------------- + +To cause Mesa to build the ``wayland-egl`` platform and Weston to build +Wayland with Kernel Mode Setting +(`KMS `__) +support, include the "wayland" flag in the +:term:`DISTRO_FEATURES` +statement in your ``local.conf`` file:: + + DISTRO_FEATURES:append = " wayland" + +.. note:: + + If X11 has been enabled elsewhere, Weston will build Wayland with X11 + support + +Installing Wayland and Weston +----------------------------- + +To install the Wayland feature into an image, you must include the +following +:term:`CORE_IMAGE_EXTRA_INSTALL` +statement in your ``local.conf`` file:: + + CORE_IMAGE_EXTRA_INSTALL += "wayland weston" + +Running Weston +============== + +To run Weston inside X11, enabling it as described earlier and building +a Sato image is sufficient. If you are running your image under Sato, a +Weston Launcher appears in the "Utility" category. + +Alternatively, you can run Weston through the command-line interpretor +(CLI), which is better suited for development work. To run Weston under +the CLI, you need to do the following after your image is built: + +#. Run these commands to export ``XDG_RUNTIME_DIR``:: + + mkdir -p /tmp/$USER-weston + chmod 0700 /tmp/$USER-weston + export XDG_RUNTIME_DIR=/tmp/$USER-weston + +#. Launch Weston in the shell:: + + weston + diff --git a/documentation/dev-manual/wic.rst b/documentation/dev-manual/wic.rst new file mode 100644 index 0000000000..213f143273 --- /dev/null +++ b/documentation/dev-manual/wic.rst @@ -0,0 +1,729 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Creating Partitioned Images Using Wic +************************************* + +Creating an image for a particular hardware target using the +OpenEmbedded build system does not necessarily mean you can boot that +image as is on your device. Physical devices accept and boot images in +various ways depending on the specifics of the device. Usually, +information about the hardware can tell you what image format the device +requires. Should your device require multiple partitions on an SD card, +flash, or an HDD, you can use the OpenEmbedded Image Creator, Wic, to +create the properly partitioned image. + +The ``wic`` command generates partitioned images from existing +OpenEmbedded build artifacts. Image generation is driven by partitioning +commands contained in an OpenEmbedded kickstart file (``.wks``) +specified either directly on the command line or as one of a selection +of canned kickstart files as shown with the ``wic list images`` command +in the +":ref:`dev-manual/wic:generate an image using an existing kickstart file`" +section. When you apply the command to a given set of build artifacts, the +result is an image or set of images that can be directly written onto media and +used on a particular system. + +.. note:: + + For a kickstart file reference, see the + ":ref:`ref-manual/kickstart:openembedded kickstart (\`\`.wks\`\`) reference`" + Chapter in the Yocto Project Reference Manual. + +The ``wic`` command and the infrastructure it is based on is by +definition incomplete. The purpose of the command is to allow the +generation of customized images, and as such, was designed to be +completely extensible through a plugin interface. See the +":ref:`dev-manual/wic:using the wic plugin interface`" section +for information on these plugins. + +This section provides some background information on Wic, describes what +you need to have in place to run the tool, provides instruction on how +to use the Wic utility, provides information on using the Wic plugins +interface, and provides several examples that show how to use Wic. + +Background +========== + +This section provides some background on the Wic utility. While none of +this information is required to use Wic, you might find it interesting. + +- The name "Wic" is derived from OpenEmbedded Image Creator (oeic). The + "oe" diphthong in "oeic" was promoted to the letter "w", because + "oeic" is both difficult to remember and to pronounce. + +- Wic is loosely based on the Meego Image Creator (``mic``) framework. + The Wic implementation has been heavily modified to make direct use + of OpenEmbedded build artifacts instead of package installation and + configuration, which are already incorporated within the OpenEmbedded + artifacts. + +- Wic is a completely independent standalone utility that initially + provides easier-to-use and more flexible replacements for an existing + functionality in OE-Core's :ref:`ref-classes-image-live` + class. The difference between Wic and those examples is that with Wic + the functionality of those scripts is implemented by a + general-purpose partitioning language, which is based on Redhat + kickstart syntax. + +Requirements +============ + +In order to use the Wic utility with the OpenEmbedded Build system, your +system needs to meet the following requirements: + +- The Linux distribution on your development host must support the + Yocto Project. See the ":ref:`detailed-supported-distros`" + section in the Yocto Project Reference Manual for the list of + distributions that support the Yocto Project. + +- The standard system utilities, such as ``cp``, must be installed on + your development host system. + +- You must have sourced the build environment setup script (i.e. + :ref:`structure-core-script`) found in the :term:`Build Directory`. + +- You need to have the build artifacts already available, which + typically means that you must have already created an image using the + OpenEmbedded build system (e.g. ``core-image-minimal``). While it + might seem redundant to generate an image in order to create an image + using Wic, the current version of Wic requires the artifacts in the + form generated by the OpenEmbedded build system. + +- You must build several native tools, which are built to run on the + build system:: + + $ bitbake wic-tools + +- Include "wic" as part of the + :term:`IMAGE_FSTYPES` + variable. + +- Include the name of the :ref:`wic kickstart file ` + as part of the :term:`WKS_FILE` variable. If multiple candidate files can + be provided by different layers, specify all the possible names through the + :term:`WKS_FILES` variable instead. + +Getting Help +============ + +You can get general help for the ``wic`` command by entering the ``wic`` +command by itself or by entering the command with a help argument as +follows:: + + $ wic -h + $ wic --help + $ wic help + +Currently, Wic supports seven commands: ``cp``, ``create``, ``help``, +``list``, ``ls``, ``rm``, and ``write``. You can get help for all these +commands except "help" by using the following form:: + + $ wic help command + +For example, the following command returns help for the ``write`` +command:: + + $ wic help write + +Wic supports help for three topics: ``overview``, ``plugins``, and +``kickstart``. You can get help for any topic using the following form:: + + $ wic help topic + +For example, the following returns overview help for Wic:: + + $ wic help overview + +There is one additional level of help for Wic. You can get help on +individual images through the ``list`` command. You can use the ``list`` +command to return the available Wic images as follows:: + + $ wic list images + genericx86 Create an EFI disk image for genericx86* + edgerouter Create SD card image for Edgerouter + beaglebone-yocto Create SD card image for Beaglebone + qemux86-directdisk Create a qemu machine 'pcbios' direct disk image + systemd-bootdisk Create an EFI disk image with systemd-boot + mkhybridiso Create a hybrid ISO image + mkefidisk Create an EFI disk image + sdimage-bootpart Create SD card image with a boot partition + directdisk-multi-rootfs Create multi rootfs image using rootfs plugin + directdisk Create a 'pcbios' direct disk image + directdisk-bootloader-config Create a 'pcbios' direct disk image with custom bootloader config + qemuriscv Create qcow2 image for RISC-V QEMU machines + directdisk-gpt Create a 'pcbios' direct disk image + efi-bootdisk + +Once you know the list of available +Wic images, you can use ``help`` with the command to get help on a +particular image. For example, the following command returns help on the +"beaglebone-yocto" image:: + + $ wic list beaglebone-yocto help + + Creates a partitioned SD card image for Beaglebone. + Boot files are located in the first vfat partition. + +Operational Modes +================= + +You can use Wic in two different modes, depending on how much control +you need for specifying the OpenEmbedded build artifacts that are used +for creating the image: Raw and Cooked: + +- *Raw Mode:* You explicitly specify build artifacts through Wic + command-line arguments. + +- *Cooked Mode:* The current + :term:`MACHINE` setting and image + name are used to automatically locate and provide the build + artifacts. You just supply a kickstart file and the name of the image + from which to use artifacts. + +Regardless of the mode you use, you need to have the build artifacts +ready and available. + +Raw Mode +-------- + +Running Wic in raw mode allows you to specify all the partitions through +the ``wic`` command line. The primary use for raw mode is if you have +built your kernel outside of the Yocto Project :term:`Build Directory`. +In other words, you can point to arbitrary kernel, root filesystem locations, +and so forth. Contrast this behavior with cooked mode where Wic looks in the +:term:`Build Directory` (e.g. ``tmp/deploy/images/``\ machine). + +The general form of the ``wic`` command in raw mode is:: + + $ wic create wks_file options ... + + Where: + + wks_file: + An OpenEmbedded kickstart file. You can provide + your own custom file or use a file from a set of + existing files as described by further options. + + optional arguments: + -h, --help show this help message and exit + -o OUTDIR, --outdir OUTDIR + name of directory to create image in + -e IMAGE_NAME, --image-name IMAGE_NAME + name of the image to use the artifacts from e.g. core- + image-sato + -r ROOTFS_DIR, --rootfs-dir ROOTFS_DIR + path to the /rootfs dir to use as the .wks rootfs + source + -b BOOTIMG_DIR, --bootimg-dir BOOTIMG_DIR + path to the dir containing the boot artifacts (e.g. + /EFI or /syslinux dirs) to use as the .wks bootimg + source + -k KERNEL_DIR, --kernel-dir KERNEL_DIR + path to the dir containing the kernel to use in the + .wks bootimg + -n NATIVE_SYSROOT, --native-sysroot NATIVE_SYSROOT + path to the native sysroot containing the tools to use + to build the image + -s, --skip-build-check + skip the build check + -f, --build-rootfs build rootfs + -c {gzip,bzip2,xz}, --compress-with {gzip,bzip2,xz} + compress image with specified compressor + -m, --bmap generate .bmap + --no-fstab-update Do not change fstab file. + -v VARS_DIR, --vars VARS_DIR + directory with .env files that store bitbake + variables + -D, --debug output debug information + +.. note:: + + You do not need root privileges to run Wic. In fact, you should not + run as root when using the utility. + +Cooked Mode +----------- + +Running Wic in cooked mode leverages off artifacts in the +:term:`Build Directory`. In other words, you do not have to specify kernel or +root filesystem locations as part of the command. All you need to provide is +a kickstart file and the name of the image from which to use artifacts +by using the "-e" option. Wic looks in the :term:`Build Directory` (e.g. +``tmp/deploy/images/``\ machine) for artifacts. + +The general form of the ``wic`` command using Cooked Mode is as follows:: + + $ wic create wks_file -e IMAGE_NAME + + Where: + + wks_file: + An OpenEmbedded kickstart file. You can provide + your own custom file or use a file from a set of + existing files provided with the Yocto Project + release. + + required argument: + -e IMAGE_NAME, --image-name IMAGE_NAME + name of the image to use the artifacts from e.g. core- + image-sato + +Using an Existing Kickstart File +================================ + +If you do not want to create your own kickstart file, you can use an +existing file provided by the Wic installation. As shipped, kickstart +files can be found in the :ref:`overview-manual/development-environment:yocto project source repositories` in the +following two locations:: + + poky/meta-yocto-bsp/wic + poky/scripts/lib/wic/canned-wks + +Use the following command to list the available kickstart files:: + + $ wic list images + genericx86 Create an EFI disk image for genericx86* + beaglebone-yocto Create SD card image for Beaglebone + edgerouter Create SD card image for Edgerouter + qemux86-directdisk Create a QEMU machine 'pcbios' direct disk image + directdisk-gpt Create a 'pcbios' direct disk image + mkefidisk Create an EFI disk image + directdisk Create a 'pcbios' direct disk image + systemd-bootdisk Create an EFI disk image with systemd-boot + mkhybridiso Create a hybrid ISO image + sdimage-bootpart Create SD card image with a boot partition + directdisk-multi-rootfs Create multi rootfs image using rootfs plugin + directdisk-bootloader-config Create a 'pcbios' direct disk image with custom bootloader config + +When you use an existing file, you +do not have to use the ``.wks`` extension. Here is an example in Raw +Mode that uses the ``directdisk`` file:: + + $ wic create directdisk -r rootfs_dir -b bootimg_dir \ + -k kernel_dir -n native_sysroot + +Here are the actual partition language commands used in the +``genericx86.wks`` file to generate an image:: + + # short-description: Create an EFI disk image for genericx86* + # long-description: Creates a partitioned EFI disk image for genericx86* machines + part /boot --source bootimg-efi --sourceparams="loader=grub-efi" --ondisk sda --label msdos --active --align 1024 + part / --source rootfs --ondisk sda --fstype=ext4 --label platform --align 1024 --use-uuid + part swap --ondisk sda --size 44 --label swap1 --fstype=swap + + bootloader --ptable gpt --timeout=5 --append="rootfstype=ext4 console=ttyS0,115200 console=tty0" + +Using the Wic Plugin Interface +============================== + +You can extend and specialize Wic functionality by using Wic plugins. +This section explains the Wic plugin interface. + +.. note:: + + Wic plugins consist of "source" and "imager" plugins. Imager plugins + are beyond the scope of this section. + +Source plugins provide a mechanism to customize partition content during +the Wic image generation process. You can use source plugins to map +values that you specify using ``--source`` commands in kickstart files +(i.e. ``*.wks``) to a plugin implementation used to populate a given +partition. + +.. note:: + + If you use plugins that have build-time dependencies (e.g. native + tools, bootloaders, and so forth) when building a Wic image, you need + to specify those dependencies using the :term:`WKS_FILE_DEPENDS` + variable. + +Source plugins are subclasses defined in plugin files. As shipped, the +Yocto Project provides several plugin files. You can see the source +plugin files that ship with the Yocto Project +:yocto_git:`here `. +Each of these plugin files contains source plugins that are designed to +populate a specific Wic image partition. + +Source plugins are subclasses of the ``SourcePlugin`` class, which is +defined in the ``poky/scripts/lib/wic/pluginbase.py`` file. For example, +the ``BootimgEFIPlugin`` source plugin found in the ``bootimg-efi.py`` +file is a subclass of the ``SourcePlugin`` class, which is found in the +``pluginbase.py`` file. + +You can also implement source plugins in a layer outside of the Source +Repositories (external layer). To do so, be sure that your plugin files +are located in a directory whose path is +``scripts/lib/wic/plugins/source/`` within your external layer. When the +plugin files are located there, the source plugins they contain are made +available to Wic. + +When the Wic implementation needs to invoke a partition-specific +implementation, it looks for the plugin with the same name as the +``--source`` parameter used in the kickstart file given to that +partition. For example, if the partition is set up using the following +command in a kickstart file:: + + part /boot --source bootimg-pcbios --ondisk sda --label boot --active --align 1024 + +The methods defined as class +members of the matching source plugin (i.e. ``bootimg-pcbios``) in the +``bootimg-pcbios.py`` plugin file are used. + +To be more concrete, here is the corresponding plugin definition from +the ``bootimg-pcbios.py`` file for the previous command along with an +example method called by the Wic implementation when it needs to prepare +a partition using an implementation-specific function:: + + . + . + . + class BootimgPcbiosPlugin(SourcePlugin): + """ + Create MBR boot partition and install syslinux on it. + """ + + name = 'bootimg-pcbios' + . + . + . + @classmethod + def do_prepare_partition(cls, part, source_params, creator, cr_workdir, + oe_builddir, bootimg_dir, kernel_dir, + rootfs_dir, native_sysroot): + """ + Called to do the actual content population for a partition i.e. it + 'prepares' the partition to be incorporated into the image. + In this case, prepare content for legacy bios boot partition. + """ + . + . + . + +If a +subclass (plugin) itself does not implement a particular function, Wic +locates and uses the default version in the superclass. It is for this +reason that all source plugins are derived from the ``SourcePlugin`` +class. + +The ``SourcePlugin`` class defined in the ``pluginbase.py`` file defines +a set of methods that source plugins can implement or override. Any +plugins (subclass of ``SourcePlugin``) that do not implement a +particular method inherit the implementation of the method from the +``SourcePlugin`` class. For more information, see the ``SourcePlugin`` +class in the ``pluginbase.py`` file for details: + +The following list describes the methods implemented in the +``SourcePlugin`` class: + +- ``do_prepare_partition()``: Called to populate a partition with + actual content. In other words, the method prepares the final + partition image that is incorporated into the disk image. + +- ``do_configure_partition()``: Called before + ``do_prepare_partition()`` to create custom configuration files for a + partition (e.g. syslinux or grub configuration files). + +- ``do_install_disk()``: Called after all partitions have been + prepared and assembled into a disk image. This method provides a hook + to allow finalization of a disk image (e.g. writing an MBR). + +- ``do_stage_partition()``: Special content-staging hook called + before ``do_prepare_partition()``. This method is normally empty. + + Typically, a partition just uses the passed-in parameters (e.g. the + unmodified value of ``bootimg_dir``). However, in some cases, things + might need to be more tailored. As an example, certain files might + additionally need to be taken from ``bootimg_dir + /boot``. This hook + allows those files to be staged in a customized fashion. + + .. note:: + + ``get_bitbake_var()`` allows you to access non-standard variables that + you might want to use for this behavior. + +You can extend the source plugin mechanism. To add more hooks, create +more source plugin methods within ``SourcePlugin`` and the corresponding +derived subclasses. The code that calls the plugin methods uses the +``plugin.get_source_plugin_methods()`` function to find the method or +methods needed by the call. Retrieval of those methods is accomplished +by filling up a dict with keys that contain the method names of +interest. On success, these will be filled in with the actual methods. +See the Wic implementation for examples and details. + +Wic Examples +============ + +This section provides several examples that show how to use the Wic +utility. All the examples assume the list of requirements in the +":ref:`dev-manual/wic:requirements`" section have been met. The +examples assume the previously generated image is +``core-image-minimal``. + +Generate an Image using an Existing Kickstart File +-------------------------------------------------- + +This example runs in Cooked Mode and uses the ``mkefidisk`` kickstart +file:: + + $ wic create mkefidisk -e core-image-minimal + INFO: Building wic-tools... + . + . + . + INFO: The new image(s) can be found here: + ./mkefidisk-201804191017-sda.direct + + The following build artifacts were used to create the image(s): + ROOTFS_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/rootfs + BOOTIMG_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share + KERNEL_DIR: /home/stephano/yocto/build/tmp-glibc/deploy/images/qemux86 + NATIVE_SYSROOT: /home/stephano/yocto/build/tmp-glibc/work/i586-oe-linux/wic-tools/1.0-r0/recipe-sysroot-native + + INFO: The image(s) were created using OE kickstart file: + /home/stephano/yocto/openembedded-core/scripts/lib/wic/canned-wks/mkefidisk.wks + +The previous example shows the easiest way to create an image by running +in cooked mode and supplying a kickstart file and the "-e" option to +point to the existing build artifacts. Your ``local.conf`` file needs to +have the :term:`MACHINE` variable set +to the machine you are using, which is "qemux86" in this example. + +Once the image builds, the output provides image location, artifact use, +and kickstart file information. + +.. note:: + + You should always verify the details provided in the output to make + sure that the image was indeed created exactly as expected. + +Continuing with the example, you can now write the image from the +:term:`Build Directory` onto a USB stick, or whatever media for which you +built your image, and boot from the media. You can write the image by using +``bmaptool`` or ``dd``:: + + $ oe-run-native bmap-tools-native bmaptool copy mkefidisk-201804191017-sda.direct /dev/sdX + +or :: + + $ sudo dd if=mkefidisk-201804191017-sda.direct of=/dev/sdX + +.. note:: + + For more information on how to use the ``bmaptool`` + to flash a device with an image, see the + ":ref:`dev-manual/bmaptool:flashing images using \`\`bmaptool\`\``" + section. + +Using a Modified Kickstart File +------------------------------- + +Because partitioned image creation is driven by the kickstart file, it +is easy to affect image creation by changing the parameters in the file. +This next example demonstrates that through modification of the +``directdisk-gpt`` kickstart file. + +As mentioned earlier, you can use the command ``wic list images`` to +show the list of existing kickstart files. The directory in which the +``directdisk-gpt.wks`` file resides is +``scripts/lib/image/canned-wks/``, which is located in the +:term:`Source Directory` (e.g. ``poky``). +Because available files reside in this directory, you can create and add +your own custom files to the directory. Subsequent use of the +``wic list images`` command would then include your kickstart files. + +In this example, the existing ``directdisk-gpt`` file already does most +of what is needed. However, for the hardware in this example, the image +will need to boot from ``sdb`` instead of ``sda``, which is what the +``directdisk-gpt`` kickstart file uses. + +The example begins by making a copy of the ``directdisk-gpt.wks`` file +in the ``scripts/lib/image/canned-wks`` directory and then by changing +the lines that specify the target disk from which to boot:: + + $ cp /home/stephano/yocto/poky/scripts/lib/wic/canned-wks/directdisk-gpt.wks \ + /home/stephano/yocto/poky/scripts/lib/wic/canned-wks/directdisksdb-gpt.wks + +Next, the example modifies the ``directdisksdb-gpt.wks`` file and +changes all instances of "``--ondisk sda``" to "``--ondisk sdb``". The +example changes the following two lines and leaves the remaining lines +untouched:: + + part /boot --source bootimg-pcbios --ondisk sdb --label boot --active --align 1024 + part / --source rootfs --ondisk sdb --fstype=ext4 --label platform --align 1024 --use-uuid + +Once the lines are changed, the +example generates the ``directdisksdb-gpt`` image. The command points +the process at the ``core-image-minimal`` artifacts for the Next Unit of +Computing (nuc) :term:`MACHINE` the +``local.conf``:: + + $ wic create directdisksdb-gpt -e core-image-minimal + INFO: Building wic-tools... + . + . + . + Initialising tasks: 100% |#######################################| Time: 0:00:01 + NOTE: Executing SetScene Tasks + NOTE: Executing RunQueue Tasks + NOTE: Tasks Summary: Attempted 1161 tasks of which 1157 didn't need to be rerun and all succeeded. + INFO: Creating image(s)... + + INFO: The new image(s) can be found here: + ./directdisksdb-gpt-201710090938-sdb.direct + + The following build artifacts were used to create the image(s): + ROOTFS_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/rootfs + BOOTIMG_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share + KERNEL_DIR: /home/stephano/yocto/build/tmp-glibc/deploy/images/qemux86 + NATIVE_SYSROOT: /home/stephano/yocto/build/tmp-glibc/work/i586-oe-linux/wic-tools/1.0-r0/recipe-sysroot-native + + INFO: The image(s) were created using OE kickstart file: + /home/stephano/yocto/poky/scripts/lib/wic/canned-wks/directdisksdb-gpt.wks + +Continuing with the example, you can now directly ``dd`` the image to a +USB stick, or whatever media for which you built your image, and boot +the resulting media:: + + $ sudo dd if=directdisksdb-gpt-201710090938-sdb.direct of=/dev/sdb + 140966+0 records in + 140966+0 records out + 72174592 bytes (72 MB, 69 MiB) copied, 78.0282 s, 925 kB/s + $ sudo eject /dev/sdb + +Using a Modified Kickstart File and Running in Raw Mode +------------------------------------------------------- + +This next example manually specifies each build artifact (runs in Raw +Mode) and uses a modified kickstart file. The example also uses the +``-o`` option to cause Wic to create the output somewhere other than the +default output directory, which is the current directory:: + + $ wic create test.wks -o /home/stephano/testwic \ + --rootfs-dir /home/stephano/yocto/build/tmp/work/qemux86-poky-linux/core-image-minimal/1.0-r0/rootfs \ + --bootimg-dir /home/stephano/yocto/build/tmp/work/qemux86-poky-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share \ + --kernel-dir /home/stephano/yocto/build/tmp/deploy/images/qemux86 \ + --native-sysroot /home/stephano/yocto/build/tmp/work/i586-poky-linux/wic-tools/1.0-r0/recipe-sysroot-native + + INFO: Creating image(s)... + + INFO: The new image(s) can be found here: + /home/stephano/testwic/test-201710091445-sdb.direct + + The following build artifacts were used to create the image(s): + ROOTFS_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/rootfs + BOOTIMG_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share + KERNEL_DIR: /home/stephano/yocto/build/tmp-glibc/deploy/images/qemux86 + NATIVE_SYSROOT: /home/stephano/yocto/build/tmp-glibc/work/i586-oe-linux/wic-tools/1.0-r0/recipe-sysroot-native + + INFO: The image(s) were created using OE kickstart file: + test.wks + +For this example, +:term:`MACHINE` did not have to be +specified in the ``local.conf`` file since the artifact is manually +specified. + +Using Wic to Manipulate an Image +-------------------------------- + +Wic image manipulation allows you to shorten turnaround time during +image development. For example, you can use Wic to delete the kernel +partition of a Wic image and then insert a newly built kernel. This +saves you time from having to rebuild the entire image each time you +modify the kernel. + +.. note:: + + In order to use Wic to manipulate a Wic image as in this example, + your development machine must have the ``mtools`` package installed. + +The following example examines the contents of the Wic image, deletes +the existing kernel, and then inserts a new kernel: + +#. *List the Partitions:* Use the ``wic ls`` command to list all the + partitions in the Wic image:: + + $ wic ls tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic + Num Start End Size Fstype + 1 1048576 25041919 23993344 fat16 + 2 25165824 72157183 46991360 ext4 + + The previous output shows two partitions in the + ``core-image-minimal-qemux86.wic`` image. + +#. *Examine a Particular Partition:* Use the ``wic ls`` command again + but in a different form to examine a particular partition. + + .. note:: + + You can get command usage on any Wic command using the following + form:: + + $ wic help command + + + For example, the following command shows you the various ways to + use the + wic ls + command:: + + $ wic help ls + + + The following command shows what is in partition one:: + + $ wic ls tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic:1 + Volume in drive : is boot + Volume Serial Number is E894-1809 + Directory for ::/ + + libcom32 c32 186500 2017-10-09 16:06 + libutil c32 24148 2017-10-09 16:06 + syslinux cfg 220 2017-10-09 16:06 + vesamenu c32 27104 2017-10-09 16:06 + vmlinuz 6904608 2017-10-09 16:06 + 5 files 7 142 580 bytes + 16 582 656 bytes free + + The previous output shows five files, with the + ``vmlinuz`` being the kernel. + + .. note:: + + If you see the following error, you need to update or create a + ``~/.mtoolsrc`` file and be sure to have the line "mtools_skip_check=1" + in the file. Then, run the Wic command again:: + + ERROR: _exec_cmd: /usr/bin/mdir -i /tmp/wic-parttfokuwra ::/ returned '1' instead of 0 + output: Total number of sectors (47824) not a multiple of sectors per track (32)! + Add mtools_skip_check=1 to your .mtoolsrc file to skip this test + + +#. *Remove the Old Kernel:* Use the ``wic rm`` command to remove the + ``vmlinuz`` file (kernel):: + + $ wic rm tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic:1/vmlinuz + +#. *Add In the New Kernel:* Use the ``wic cp`` command to add the + updated kernel to the Wic image. Depending on how you built your + kernel, it could be in different places. If you used ``devtool`` and + an SDK to build your kernel, it resides in the ``tmp/work`` directory + of the extensible SDK. If you used ``make`` to build the kernel, the + kernel will be in the ``workspace/sources`` area. + + The following example assumes ``devtool`` was used to build the + kernel:: + + $ wic cp poky_sdk/tmp/work/qemux86-poky-linux/linux-yocto/4.12.12+git999-r0/linux-yocto-4.12.12+git999/arch/x86/boot/bzImage \ + poky/build/tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic:1/vmlinuz + + Once the new kernel is added back into the image, you can use the + ``dd`` command or :ref:`bmaptool + ` + to flash your wic image onto an SD card or USB stick and test your + target. + + .. note:: + + Using ``bmaptool`` is generally 10 to 20 times faster than using ``dd``. + diff --git a/documentation/dev-manual/x32-psabi.rst b/documentation/dev-manual/x32-psabi.rst new file mode 100644 index 0000000000..92b1f96fa4 --- /dev/null +++ b/documentation/dev-manual/x32-psabi.rst @@ -0,0 +1,54 @@ +.. SPDX-License-Identifier: CC-BY-SA-2.0-UK + +Using x32 psABI +*************** + +x32 processor-specific Application Binary Interface (`x32 +psABI `__) is a native +32-bit processor-specific ABI for Intel 64 (x86-64) architectures. An +ABI defines the calling conventions between functions in a processing +environment. The interface determines what registers are used and what +the sizes are for various C data types. + +Some processing environments prefer using 32-bit applications even when +running on Intel 64-bit platforms. Consider the i386 psABI, which is a +very old 32-bit ABI for Intel 64-bit platforms. The i386 psABI does not +provide efficient use and access of the Intel 64-bit processor +resources, leaving the system underutilized. Now consider the x86_64 +psABI. This ABI is newer and uses 64-bits for data sizes and program +pointers. The extra bits increase the footprint size of the programs, +libraries, and also increases the memory and file system size +requirements. Executing under the x32 psABI enables user programs to +utilize CPU and system resources more efficiently while keeping the +memory footprint of the applications low. Extra bits are used for +registers but not for addressing mechanisms. + +The Yocto Project supports the final specifications of x32 psABI as +follows: + +- You can create packages and images in x32 psABI format on x86_64 + architecture targets. + +- You can successfully build recipes with the x32 toolchain. + +- You can create and boot ``core-image-minimal`` and + ``core-image-sato`` images. + +- There is RPM Package Manager (RPM) support for x32 binaries. + +- There is support for large images. + +To use the x32 psABI, you need to edit your ``conf/local.conf`` +configuration file as follows:: + + MACHINE = "qemux86-64" + DEFAULTTUNE = "x86-64-x32" + baselib = "${@d.getVar('BASE_LIB:tune-' + (d.getVar('DEFAULTTUNE') \ + or 'INVALID')) or 'lib'}" + +Once you have set +up your configuration file, use BitBake to build an image that supports +the x32 psABI. Here is an example:: + + $ bitbake core-image-sato +