On Thu, Jun 17, 2021 at 10:05 AM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote: > > On Sat, Jun 12, 2021 at 11:18 PM Matthias Maennich <maennich@xxxxxxxxxx> wrote: > > > > To avoid unnecessary recompilations, mkcompile_h does not regenerate > > compile.h if just the timestamp changed. > > Though, if KBUILD_BUILD_TIMESTAMP is set, an explicit timestamp for the > > build was requested, in which case we should not ignore it. > > > > If a user follows the documentation for reproducible builds [1] and > > defines KBUILD_BUILD_TIMESTAMP as the git commit timestamp, a clean > > build will have the correct timestamp. A subsequent cherry-pick (or > > amend) changes the commit timestamp and if an incremental build is done > > with a different KBUILD_BUILD_TIMESTAMP now, that new value is not taken > > into consideration. But it should for reproducibility. > > > > Hence, whenever KBUILD_BUILD_TIMESTAMP is explicitly set, do not ignore > > UTS_VERSION when making a decision about whether the regenerated version > > of compile.h should be moved into place. > > > > [1] https://www.kernel.org/doc/html/latest/kbuild/reproducible-builds.html > > > > Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx> > > Cc: linux-kbuild@xxxxxxxxxxxxxxx > > Signed-off-by: Matthias Maennich <maennich@xxxxxxxxxx> > > --- > > > Applied to linux-kbuild. Thanks. > This may not be a big deal, but when KBUILD_BUILD_TIMESTAMP is unset, the timestamp is not updated. It still has a user-specified string. -- Best Regards Masahiro Yamada
