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authorMatthias Maennich <maennich@google.com>2021-06-12 15:18:38 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-07-28 11:12:15 +0200
commitfaddc739b3b1c1e68ed513961257cab777730b47 (patch)
tree8f31ee06c303a6a4581e647e0670caa1f53fa96f /scripts
parent3c2472909d7ed1c5c1f6adb9e5edc2eaa80ef427 (diff)
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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-xscripts/mkcompile_h14
1 files changed, 11 insertions, 3 deletions
diff --git a/scripts/mkcompile_h b/scripts/mkcompile_h
index 959199c3147e..49f92fffa098 100755
--- a/scripts/mkcompile_h
+++ b/scripts/mkcompile_h
@@ -83,15 +83,23 @@ 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