On 2022-02-21 05:13, Bruce Ashfield wrote:
on 19/02/2022 Jimmy Assarsson wrote:
On 2022-02-19 20:42, Bruce Ashfield wrote:
On Sat, Feb 19, 2022 at 5:28 AM Jimmy Assarsson
<[email protected]> wrote:
When patching a kernel git repository, in a recipe inheriting
kernel-yocto.bbclass,
the resulting commit hash will become different every time the source is
unpacked and patched.
This is a problem that causes non-reproducible builds, when the commit hash is
built
into the kernel (CONFIG_LOCALVERSION_AUTO=y).
Currently it is not a problem in linux-yocto, since an empty .scmversion is
created in kernel_do_configure [1]. This is preventing the kernel build from
generating its own .scmversion.
If removing this commit, setting CONFIG_LOCALVERSION_AUTO=y and applying any
patch in the linux-yocto recipe, this will result in a non-reproducible build.
...
diff --git a/tools/kgit-s2q b/tools/kgit-s2q
index 706783e..b46a138 100755
--- a/tools/kgit-s2q
+++ b/tools/kgit-s2q
@@ -558,7 +558,7 @@ do
echo "($APPLIED/$COUNT) `basename $i`"
fi
- git am --keep-non-patch $DIR/$i > /dev/null 2>&1
+ git am --keep-non-patch --committer-date-is-author-date $DIR/$i > /dev/null
2>&1
if [ $? != 0 ];then
git am --abort > /dev/null 2>&1
echo "[INFO]: check of $DIR/$i with \"git am\" did not pass,
trying reduced context."
I'm not sure if this is a proper solution to fix the problem or what side
effects it may introduce?
There's nothing fundamentally wrong with that solution, but there are
modes for the kernel builds where we absolutely do not want the
reproducible build (and older dates) to be in effect (see my comments
on the OE core mailing list when the ability to disable reproducible
builds was almost removed).
Thanks, now I've looked it up.
We could add an option to the patch queue management that was enabled
when reproducible builds are in play, so git am could operate like
that.
Alternatively, you could bbappend the other kernel's do_configure and
do the same .scmversion trick to make sure that everything is
consistent.
I don't follow, can you be more specific?
We encountered this problem when building linux-imx (from meta-freescale).
Preferably the .scmversion workaround in [1] should be dropped, so that
there is no need to reinvent/mimic the output of
linux/scripts/setlocalversion, in a bitbake recipe.
I see no compelling reason to drop the .scmversion in the main kernel.bbclass
(at least not in the short term). It has been there for a significant amount
of time, and removing it now would very likely cause some ripple effects
througout the ecosystem (it is there for a few different issues). While not
elegant, it is an available and workable solution to the problem it is
solving.
I agree. And obviously this is not a big issue for others.
There have been at least two failed attempts on removing this [4][5][6].
I was suggesting that anyone can bbappend any kernel recipe to do the similar
.scmversion set (assuming they aren't using the core kernel bbclass
configure()).
But from your next statement, that isn't going to work as the sole solution,
since yes, that will only restore where we keep the git rev out of the
localversion.
To be clear, we want the result of CONFIG_LOCALVERSION_AUTO=y, but
with a reproducible output.
And that's actually part of the reason the .scmversion is set, the
setlocalversion script was appending values in some configurations and
combinations of patching, etc, such that issues were popping up with version
matching.
Part of getting that to work, definitely could be to apply patches with the
author date, but that has to be triggered on reproducible builds being
enabled (which is of course the default) and also preserving the use of the
.scmversion for the baseline / basic kernel configuration routines.
.. so one config to say "don't set scmversion" and another to say "apply
patches with author date" (this one toggling based on reproducible builds).
And then both scenarios can be supported.
Currently I'm only interested in fixing the "apply patches with
author date", to get reproducible builds.
So we will end up with a new config in kernel-yocto.bbclass, since this
is the only location where kgit-s2q is used.
And we will get a new option in kgit-s2q, that will result in
"git am --committer-date-is-author-date" being used.
Any name suggestions for the config and option?
KERNEL_PATCH_WITH_AUTHOR_DATE
KERNEL_PATCH_REPRODUCIBLE_HASH
KERNEL_PATCH_REPRODUCIBLE_COMMIT
--patch-with-author-date
--apply-patch-with-author-date
--committer-date-is-author-date
[4] https://patchwork.openembedded.org/patch/138333
[5] https://patchwork.openembedded.org/patch/171479
[6] https://patchwork.openembedded.org/patch/171513
Best regards,
jimmy
Bruce
Best regards,
jimmy
Bruce
[1]
https://git.yoctoproject.org/poky/tree/meta/classes/kernel.bbclass?h=honister#n589
[2]
https://git.yoctoproject.org/meta-freescale/tree/classes/fsl-kernel-localversion.bbclass?h=honister
[3]
https://github.com/OE4T/meta-tegra/blob/honister/recipes-kernel/linux/linux-tegra_4.9.bb
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