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a979522a1a
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>
94 lines
2.5 KiB
Bash
Executable file
94 lines
2.5 KiB
Bash
Executable file
#!/bin/sh
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# SPDX-License-Identifier: GPL-2.0
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TARGET=$1
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ARCH=$2
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SMP=$3
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PREEMPT=$4
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PREEMPT_RT=$5
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CC_VERSION="$6"
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LD=$7
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# Do not expand names
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set -f
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# Fix the language to get consistent output
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LC_ALL=C
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export LC_ALL
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if [ -z "$KBUILD_BUILD_VERSION" ]; then
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VERSION=$(cat .version 2>/dev/null || echo 1)
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else
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VERSION=$KBUILD_BUILD_VERSION
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fi
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if [ -z "$KBUILD_BUILD_TIMESTAMP" ]; then
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TIMESTAMP=`date`
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else
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TIMESTAMP=$KBUILD_BUILD_TIMESTAMP
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fi
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if test -z "$KBUILD_BUILD_USER"; then
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LINUX_COMPILE_BY=$(whoami | sed 's/\\/\\\\/')
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else
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LINUX_COMPILE_BY=$KBUILD_BUILD_USER
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fi
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if test -z "$KBUILD_BUILD_HOST"; then
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LINUX_COMPILE_HOST=`uname -n`
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else
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LINUX_COMPILE_HOST=$KBUILD_BUILD_HOST
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fi
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UTS_VERSION="#$VERSION"
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CONFIG_FLAGS=""
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if [ -n "$SMP" ] ; then CONFIG_FLAGS="SMP"; fi
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if [ -n "$PREEMPT" ] ; then CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT"; fi
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if [ -n "$PREEMPT_RT" ] ; then CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT_RT"; fi
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# Truncate to maximum length
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UTS_LEN=64
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UTS_VERSION="$(echo $UTS_VERSION $CONFIG_FLAGS $TIMESTAMP | cut -b -$UTS_LEN)"
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# Generate a temporary compile.h
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{ echo /\* This file is auto generated, version $VERSION \*/
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if [ -n "$CONFIG_FLAGS" ] ; then echo "/* $CONFIG_FLAGS */"; fi
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echo \#define UTS_MACHINE \"$ARCH\"
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echo \#define UTS_VERSION \"$UTS_VERSION\"
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printf '#define LINUX_COMPILE_BY "%s"\n' "$LINUX_COMPILE_BY"
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echo \#define LINUX_COMPILE_HOST \"$LINUX_COMPILE_HOST\"
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LD_VERSION=$($LD -v | head -n1 | sed 's/(compatible with [^)]*)//' \
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| sed 's/[[:space:]]*$//')
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printf '#define LINUX_COMPILER "%s"\n' "$CC_VERSION, $LD_VERSION"
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} > .tmpcompile
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# Only replace the real compile.h if the new one is different,
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# in order to preserve the timestamp and avoid unnecessary
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# recompilations.
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# We don't consider the file changed if only the date/time changed,
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# unless KBUILD_BUILD_TIMESTAMP was explicitly set (e.g. for
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# reproducible builds with that value referring to a commit timestamp).
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# A kernel config change will increase the generation number, thus
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# causing compile.h to be updated (including date/time) due to the
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# changed comment in the
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# first line.
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if [ -z "$KBUILD_BUILD_TIMESTAMP" ]; then
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IGNORE_PATTERN="UTS_VERSION"
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else
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IGNORE_PATTERN="NOT_A_PATTERN_TO_BE_MATCHED"
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fi
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if [ -r $TARGET ] && \
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grep -v $IGNORE_PATTERN $TARGET > .tmpver.1 && \
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grep -v $IGNORE_PATTERN .tmpcompile > .tmpver.2 && \
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cmp -s .tmpver.1 .tmpver.2; then
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rm -f .tmpcompile
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else
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echo " UPD $TARGET"
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mv -f .tmpcompile $TARGET
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fi
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rm -f .tmpver.1 .tmpver.2
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