@@ -4299,9 +4299,33 @@ system and gives an overview of their function and contents.
IMAGE_ROOTFS_EXTRA_SPACE = "41943040"
:term:`IMAGE_ROOTFS_MAXSIZE`
- Defines the maximum size in Kbytes for the generated image. If the
- generated image size is above that, the build will fail. It's a good
- idea to set this variable for images that need to fit on a limited
+ Defines the maximum allowed size of the generated image in kilobytes.
+ The build will fail if the generated image size exceeds this value.
+
+ The generated image size undergoes several calculation steps before being
+ compared to :term:`IMAGE_ROOTFS_MAXSIZE`.
+ In the first step, the size of the directory pointed to by :term:`IMAGE_ROOTFS`
+ is calculated.
+ In the second step, the result from the first step is multiplied
+ by :term:`IMAGE_OVERHEAD_FACTOR`.
+ In the third step, the result from the second step is compared with
+ :term:`IMAGE_ROOTFS_SIZE`. The larger value of these is added to
+ :term:`IMAGE_ROOTFS_EXTRA_SPACE`.
+ In the fourth step, the result from the third step is checked for
+ a decimal part. If it has one, it is rounded up to the next integer.
+ If it does not, it is simply converted into an integer.
+ In the fifth step, the :term:`IMAGE_ROOTFS_ALIGNMENT` is added to the result
+ from the fourth step and "1" is subtracted.
+ In the sixth step, the remainder of the division between the result
+ from the fifth step and :term:`IMAGE_ROOTFS_ALIGNMENT` is subtracted from the
+ result of the fifth step. In this way, the result from the fourth step is
+ rounded up to the nearest multiple of :term:`IMAGE_ROOTFS_ALIGNMENT`.
+
+ Thus, if the :term:`IMAGE_ROOTFS_MAXSIZE` is set, is compared with the result
+ of the above calculations and is independent of the final image type.
+ No default value is set for :term:`IMAGE_ROOTFS_MAXSIZE`.
+
+ It's a good idea to set this variable for images that need to fit on a limited
space (e.g. SD card, a fixed-size partition, ...).
:term:`IMAGE_ROOTFS_SIZE`
This variable specifies the maximum allowed size of the generated image in kilobytes. CC: Yoann Congal <yoann.congal@smile.fr> CC: Randy MacLeod <randy.macleod@windriver.com> CC: Antonin Godard <antonin.godard@bootlin.com> CC: Quentin Schulz <quentin.schulz@cherry.de> Signed-off-by: Christos Gavros <gavrosc@yahoo.com> --- documentation/ref-manual/variables.rst | 30 +++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-)