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2df8220cc5
Kbuild builds init/built-in.a twice; first during the ordinary
directory descending, second from scripts/link-vmlinux.sh.
We do this because UTS_VERSION contains the build version and the
timestamp. We cannot update it during the normal directory traversal
since we do not yet know if we need to update vmlinux. UTS_VERSION is
temporarily calculated, but omitted from the update check. Otherwise,
vmlinux would be rebuilt every time.
When Kbuild results in running link-vmlinux.sh, it increments the
version number in the .version file and takes the timestamp at that
time to really fix UTS_VERSION.
However, updating the same file twice is a footgun. To avoid nasty
timestamp issues, all build artifacts that depend on init/built-in.a
are atomically generated in link-vmlinux.sh, where some of them do not
need rebuilding.
To fix this issue, this commit changes as follows:
[1] Split UTS_VERSION out to include/generated/utsversion.h from
include/generated/compile.h
include/generated/utsversion.h is generated just before the
vmlinux link. It is generated under include/generated/ because
some decompressors (s390, x86) use UTS_VERSION.
[2] Split init_uts_ns and linux_banner out to init/version-timestamp.c
from init/version.c
init_uts_ns and linux_banner contain UTS_VERSION. During the ordinary
directory descending, they are compiled with __weak and used to
determine if vmlinux needs relinking. Just before the vmlinux link,
they are compiled without __weak to embed the real version and
timestamp.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
95 lines
3.2 KiB
Bash
Executable file
95 lines
3.2 KiB
Bash
Executable file
#!/bin/sh
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# SPDX-License-Identifier: GPL-2.0
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# This script generates an archive consisting of kernel headers
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# for CONFIG_IKHEADERS.
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set -e
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sfile="$(readlink -f "$0")"
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outdir="$(pwd)"
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tarfile=$1
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cpio_dir=$outdir/$tarfile.tmp
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dir_list="
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include/
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arch/$SRCARCH/include/
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"
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# Support incremental builds by skipping archive generation
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# if timestamps of files being archived are not changed.
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# This block is useful for debugging the incremental builds.
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# Uncomment it for debugging.
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# if [ ! -f /tmp/iter ]; then iter=1; echo 1 > /tmp/iter;
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# else iter=$(($(cat /tmp/iter) + 1)); echo $iter > /tmp/iter; fi
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# find $all_dirs -name "*.h" | xargs ls -l > /tmp/ls-$iter
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all_dirs=
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if [ "$building_out_of_srctree" ]; then
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for d in $dir_list; do
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all_dirs="$all_dirs $srctree/$d"
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done
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fi
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all_dirs="$all_dirs $dir_list"
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# include/generated/utsversion.h is ignored because it is generated after this
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# script is executed. (utsversion.h is unneeded for kheaders)
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#
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# When Kconfig regenerates include/generated/autoconf.h, its timestamp is
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# updated, but the contents might be still the same. When any CONFIG option is
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# changed, Kconfig touches the corresponding timestamp file include/config/*.
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# Hence, the md5sum detects the configuration change anyway. We do not need to
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# check include/generated/autoconf.h explicitly.
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#
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# Ignore them for md5 calculation to avoid pointless regeneration.
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headers_md5="$(find $all_dirs -name "*.h" |
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grep -v "include/generated/utsversion.h" |
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grep -v "include/generated/autoconf.h" |
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xargs ls -l | md5sum | cut -d ' ' -f1)"
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# Any changes to this script will also cause a rebuild of the archive.
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this_file_md5="$(ls -l $sfile | md5sum | cut -d ' ' -f1)"
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if [ -f $tarfile ]; then tarfile_md5="$(md5sum $tarfile | cut -d ' ' -f1)"; fi
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if [ -f kernel/kheaders.md5 ] &&
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[ "$(head -n 1 kernel/kheaders.md5)" = "$headers_md5" ] &&
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[ "$(head -n 2 kernel/kheaders.md5 | tail -n 1)" = "$this_file_md5" ] &&
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[ "$(tail -n 1 kernel/kheaders.md5)" = "$tarfile_md5" ]; then
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exit
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fi
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echo " GEN $tarfile"
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rm -rf $cpio_dir
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mkdir $cpio_dir
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if [ "$building_out_of_srctree" ]; then
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(
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cd $srctree
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for f in $dir_list
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do find "$f" -name "*.h";
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done | cpio --quiet -pd $cpio_dir
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)
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fi
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# The second CPIO can complain if files already exist which can happen with out
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# of tree builds having stale headers in srctree. Just silence CPIO for now.
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for f in $dir_list;
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do find "$f" -name "*.h";
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done | cpio --quiet -pdu $cpio_dir >/dev/null 2>&1
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# Remove comments except SDPX lines
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find $cpio_dir -type f -print0 |
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xargs -0 -P8 -n1 perl -pi -e 'BEGIN {undef $/;}; s/\/\*((?!SPDX).)*?\*\///smg;'
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# Create archive and try to normalize metadata for reproducibility.
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# For compatibility with older versions of tar, files are fed to tar
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# pre-sorted, as --sort=name might not be available.
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find $cpio_dir -printf "./%P\n" | LC_ALL=C sort | \
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tar "${KBUILD_BUILD_TIMESTAMP:+--mtime=$KBUILD_BUILD_TIMESTAMP}" \
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--owner=0 --group=0 --numeric-owner --no-recursion \
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-I $XZ -cf $tarfile -C $cpio_dir/ -T - > /dev/null
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echo $headers_md5 > kernel/kheaders.md5
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echo "$this_file_md5" >> kernel/kheaders.md5
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echo "$(md5sum $tarfile | cut -d ' ' -f1)" >> kernel/kheaders.md5
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rm -rf $cpio_dir
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