On Tue, Jul 2, 2024 at 2:32 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote:
>
> Reproducible builds [1] require that the same source code with
> the same set of tools can build identical objects each time,
> but pahole in parallel mode was non-deterministic in
> BTF generation prior to
>
> dba7b5e ("pahole: Encode BTF serially in a reproducible build")
>
> This was a problem since said BTF is baked into kernels and modules in
> .BTF sections, so parallel pahole was causing non-reproducible binary
> generation. Now with the above commit we have support for parallel
> reproducible BTF generation in pahole.
>
> KBUILD_BUILD_TIMESTAMP is set for reproducible builds, so if it
> is set, add reproducible_build to --btf_features.
>
> [1] Documentation/kbuild/reproducible-builds.rst
>
> Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
Does not make sense.
KBUILD_BUILD_TIMESTAMP is not a switch for
"please enable the reproducible build".
KBUILD_BUILD_TIMESTAMP requires the build code
to use the given time in the output where timestamps are used.
Your patch does not use the timestamp at all.
If --btf_features=reproducible_build has no downside,
please add it whenever supported.
> ---
> scripts/Makefile.btf | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/scripts/Makefile.btf b/scripts/Makefile.btf
> index b75f09f3f424..40bb72662967 100644
> --- a/scripts/Makefile.btf
> +++ b/scripts/Makefile.btf
> @@ -21,6 +21,10 @@ else
> # Switch to using --btf_features for v1.26 and later.
> pahole-flags-$(call test-ge, $(pahole-ver), 126) = -j --btf_features=encode_force,var,float,enum64,decl_tag,type_tag,optimized_func,consistent_func,decl_tag_kfuncs
>
> +ifneq ($(KBUILD_BUILD_TIMESTAMP),)
> +pahole-flags-$(call test-ge, $(pahole-ver), 126) += --btf_features=reproducible_build
> +endif
> +
> ifneq ($(KBUILD_EXTMOD),)
> module-pahole-flags-$(call test-ge, $(pahole-ver), 126) += --btf_features=distilled_base
> endif
> --
> 2.31.1
>
--
Best Regards
Masahiro Yamada
