diff options
| author | Matthias Maennich <maennich@google.com> | 2021-06-12 15:18:38 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-07-25 14:35:12 +0200 |
| commit | 199d8ea4c7b147aff74dde8da817b40c8f23505b (patch) | |
| tree | 07dd13eeae0d6f361bee8fc72c4169a507a88baa /scripts | |
| parent | 484193b635a76e8621d1ae156770543070f5f7dd (diff) | |
kbuild: mkcompile_h: consider timestamp if KBUILD_BUILD_TIMESTAMP is set
[ Upstream commit a979522a1a88556e42a22ce61bccc58e304cb361 ]
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
Signed-off-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'scripts')
| -rwxr-xr-x | scripts/mkcompile_h | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/scripts/mkcompile_h b/scripts/mkcompile_h index d1d757c6edf4..06c1e9e3bc38 100755 --- a/scripts/mkcompile_h +++ b/scripts/mkcompile_h @@ -80,15 +80,23 @@ UTS_TRUNCATE="cut -b -$UTS_LEN" # Only replace the real compile.h if the new one is different, # in order to preserve the timestamp and avoid unnecessary # recompilations. -# We don't consider the file changed if only the date/time changed. +# We don't consider the file changed if only the date/time changed, +# unless KBUILD_BUILD_TIMESTAMP was explicitly set (e.g. for +# reproducible builds with that value referring to a commit timestamp). # A kernel config change will increase the generation number, thus # causing compile.h to be updated (including date/time) due to the # changed comment in the # first line. +if [ -z "$KBUILD_BUILD_TIMESTAMP" ]; then + IGNORE_PATTERN="UTS_VERSION" +else + IGNORE_PATTERN="NOT_A_PATTERN_TO_BE_MATCHED" +fi + if [ -r $TARGET ] && \ - grep -v 'UTS_VERSION' $TARGET > .tmpver.1 && \ - grep -v 'UTS_VERSION' .tmpcompile > .tmpver.2 && \ + grep -v $IGNORE_PATTERN $TARGET > .tmpver.1 && \ + grep -v $IGNORE_PATTERN .tmpcompile > .tmpver.2 && \ cmp -s .tmpver.1 .tmpver.2; then rm -f .tmpcompile else |