[bitbake-devel] Forcing the rebuild of dependent tasks across recipes

[Matthias Schiffer]

Hi all,

is there a robust way to enforce the automatic rebuild of dependent
tasks across recipes? I'm having the following issue:

- Recipe my-core-image has an output file that is copied to the deploy
dir. The output file is not fully reproducible, so cleaning the recipe
and rebuilding it will yield a different file even through the sstate
signature of the recipe is unchanged (the file I'm interested is
DMVerity hash data that I generate as an additional filesystem type)

- Task do_compile of recipe my-initramfs-scripts depends on my-core-
image:do_image_complete. I need to enforce rebuilding of this task
whenever the deployed files of my-core-image have changed (the recipe
uses the "root hash" generated by DMVerity as input, so that the
filesystem can be verified on mount) - and of course also of all
dependent tasks like the initramfs image and FIT kernel image

I've experimented with things like file-checksums and BB_DONT_CACHE,
but everything I've tried fails when the rebuilds of my-core-image and
my-initramfs-scripts are supposed to happen in the same run of Bitbake:

- file-checksums only seems to be taken into account at initial recipe
parse time, not when the task I'm interested in is actually executed? I
need to run bitbake twice to get the correct results.
- When I use an anonymous Python function to put the root hash I'm
interested in into a variable, Bitbake complains about nondeterministic
metadata.

Using nostamp would be an option, but obviously an ugly one.

I'm currently on Yocto Thud / Bitbake 1.40.


Thanks in advance,

Matthias