From patchwork Wed Feb 16 20:17:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alejandro Enedino Hernandez Samaniego X-Patchwork-Id: 3662 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id A44BEC433F5 for ; Wed, 16 Feb 2022 20:17:40 +0000 (UTC) Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by mx.groups.io with SMTP id smtpd.web08.697.1645042659930775233 for ; Wed, 16 Feb 2022 12:17:40 -0800 Authentication-Results: mx.groups.io; dkim=fail reason="body hash did not verify" header.i=@linux.microsoft.com header.s=default header.b=fRrQMkRQ; spf=pass (domain: linux.microsoft.com, ip: 13.77.154.182, mailfrom: alhe@linux.microsoft.com) Received: from alsamon-xub.lan (cpe-70-112-59-126.austin.res.rr.com [70.112.59.126]) by linux.microsoft.com (Postfix) with ESMTPSA id 1F62F20BA5D3; Wed, 16 Feb 2022 12:17:39 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 1F62F20BA5D3 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1645042659; bh=vGH8JEu1sS402a7rKIoWGLpbICMFZPU0npWh7mFZi2k=; h=From:To:Cc:Subject:Date:From; b=fRrQMkRQgvLRS0XKgcArRdEKPKYTVwn+/x5l6S8q8+G+sVpPzTfPJYwnT2FFYmx8g FDt2/D08PLZiMe9+2MaF+QLo19+5S086AtUB4l8SztSwrx17lHyQl3FnelR2LhQhaW YcKTXDS6+FthdFAMTj8oo5MVahvwsJ+NSnBGAG1U= From: Alejandro Enedino Hernandez Samaniego To: docs@lists.yoctoproject.org Cc: Alejandro Enedino Hernandez Samaniego Subject: [PATCH v2] documentation: Add multiconfig initramfs configuration: Date: Wed, 16 Feb 2022 13:17:31 -0700 Message-Id: <20220216201731.2699414-1-alhe@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 List-Id: X-Webhook-Received: from li982-79.members.linode.com [45.33.32.79] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Wed, 16 Feb 2022 20:17:40 -0000 X-Groupsio-URL: https://lists.yoctoproject.org/g/docs/message/2469 dev-manual/common-tasks.rst: Add section to create an initramfs image from a separate multiconfig. ref-manual/variables.rst: Add new variable definitions for INITRAMFS_DEPLOY_DIR_IMAGE and INITRAMFS_MULTICONFIG Signed-off-by: Alejandro Enedino Hernandez Samaniego Reviewed-by: Michael Opdenacker --- documentation/dev-manual/common-tasks.rst | 42 +++++++++++++++++++++++ documentation/ref-manual/variables.rst | 17 +++++++++ 2 files changed, 59 insertions(+) diff --git a/documentation/dev-manual/common-tasks.rst b/documentation/dev-manual/common-tasks.rst index d35b590ee..dec44d378 100644 --- a/documentation/dev-manual/common-tasks.rst +++ b/documentation/dev-manual/common-tasks.rst @@ -3919,6 +3919,48 @@ Follow these steps to create an initramfs image: :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/${MACHINE}" + + The variables :term:`INITRAMFS_MULTICONFIG` and :term:`INITRAMFS_DEPLOY_DIR_IMAGE` + are used to create a multiconfig dependency from the kernel to the :term:`INITRAMFS_IMAGE` + to be built coming from the ``initramfscfg`` multiconfig, and to let the + buildsystem know where the :term:`INITRAMFS_IMAGE` will be located. + + Building a system with such configuration will build the kernel using the + main configuration but the ``do_bundle_initramfs`` task will grab the + selected :term:`INITRAMFS_IMAGE` from :term:`INITRAMFS_DEPLOY_DIR_IMAGE` + instead, resulting in a musl based initramfs image bundled in the kernel + but a glibc based main image. + + The same is applicable to avoid inheriting :term:`DISTRO_FEATURES` on :term:`INITRAMFS_IMAGE` + or to build a different :term:`DISTRO` for it such as ``poky-tiny``. + + Building a Tiny System ---------------------- diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst index d4f40b692..caa971393 100644 --- a/documentation/ref-manual/variables.rst +++ b/documentation/ref-manual/variables.rst @@ -3554,6 +3554,13 @@ system and gives an overview of their function and contents. even if the toolchain's binaries are strippable, there are other files needed for the build that are not strippable. + :term:`INITRAMFS_DEPLOY_DIR_IMAGE` + Indicates the deploy directory used by ``do_bundle_initramfs`` where the + :term:`INITRAMFS_IMAGE` will be fetched from. + This variable is set by default to ``${DEPLOY_DIR_IMAGE}`` in the + :ref:`kernel ` class and it's only meant to be changed + when building an initramfs image from a separate multiconfig via :term:`INITRAMFS_MULTICONFIG`. + :term:`INITRAMFS_FSTYPES` Defines the format for the output image of an initial RAM filesystem (initramfs), which is used during boot. Supported formats are the @@ -3673,6 +3680,16 @@ system and gives an overview of their function and contents. See the :term:`MACHINE` variable for additional information. + :term:`INITRAMFS_MULTICONFIG` + Defines the multiconfig to create a multiconfig dependency to be used by the :ref:`kernel ` class. + + This allows the kernel to bundle an :term:`INITRAMFS_IMAGE` coming from + a separate multiconfig, this is meant to be used in addition to :term:`INITRAMFS_DEPLOY_DIR_IMAGE`. + + For more information on how to bundle an initramfs image from a separate + multiconfig see the ":ref:`dev-manual/common-tasks:Bundling an Initramfs Image From a Separate Multiconfig`" + section in the Yocto Project Development Tasks Manual. + :term:`INITRAMFS_NAME` The base name of the initial RAM filesystem image. This variable is set in the ``meta/classes/kernel-artifact-names.bbclass`` file as