linux/kernel/gen_kheaders.sh
Joel Fernandes (Google) 1457dc9ed8 kheaders: Do not regenerate archive if config is not changed
Linus reported an issue that doing an allmodconfig was causing the
kheaders archive to be regenerated even though the config is the same.
This patch fixes the issue by ignoring the config-related header files
for "knowing when to regenerate based on timestamps".  Instead, if the
CONFIG_X_Y option really changes, then we there are the
include/config/X/Y.h which will already tells us "if a config really
changed". So we don't really need these files for regeneration detection
anyway, and ignoring them fixes Linus's issue.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-24 20:16:01 +02:00

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#!/bin/bash
# SPDX-License-Identifier: GPL-2.0
# This script generates an archive consisting of kernel headers
# for CONFIG_IKHEADERS.
set -e
spath="$(dirname "$(readlink -f "$0")")"
kroot="$spath/.."
outdir="$(pwd)"
tarfile=$1
cpio_dir=$outdir/$tarfile.tmp
# Script filename relative to the kernel source root
# We add it to the archive because it is small and any changes
# to this script will also cause a rebuild of the archive.
sfile="$(realpath --relative-to $kroot "$(readlink -f "$0")")"
src_file_list="
include/
arch/$SRCARCH/include/
$sfile
"
obj_file_list="
include/
arch/$SRCARCH/include/
"
# Support incremental builds by skipping archive generation
# if timestamps of files being archived are not changed.
# This block is useful for debugging the incremental builds.
# Uncomment it for debugging.
# if [ ! -f /tmp/iter ]; then iter=1; echo 1 > /tmp/iter;
# else iter=$(($(cat /tmp/iter) + 1)); echo $iter > /tmp/iter; fi
# find $src_file_list -type f | xargs ls -lR > /tmp/src-ls-$iter
# find $obj_file_list -type f | xargs ls -lR > /tmp/obj-ls-$iter
# include/generated/compile.h is ignored because it is touched even when none
# of the source files changed. This causes pointless regeneration, so let us
# ignore them for md5 calculation.
pushd $kroot > /dev/null
src_files_md5="$(find $src_file_list -type f |
grep -v "include/generated/compile.h" |
grep -v "include/generated/autoconf.h" |
grep -v "include/config/auto.conf" |
grep -v "include/config/auto.conf.cmd" |
grep -v "include/config/tristate.conf" |
xargs ls -lR | md5sum | cut -d ' ' -f1)"
popd > /dev/null
obj_files_md5="$(find $obj_file_list -type f |
grep -v "include/generated/compile.h" |
grep -v "include/generated/autoconf.h" |
grep -v "include/config/auto.conf" |
grep -v "include/config/auto.conf.cmd" |
grep -v "include/config/tristate.conf" |
xargs ls -lR | md5sum | cut -d ' ' -f1)"
if [ -f $tarfile ]; then tarfile_md5="$(md5sum $tarfile | cut -d ' ' -f1)"; fi
if [ -f kernel/kheaders.md5 ] &&
[ "$(cat kernel/kheaders.md5|head -1)" == "$src_files_md5" ] &&
[ "$(cat kernel/kheaders.md5|head -2|tail -1)" == "$obj_files_md5" ] &&
[ "$(cat kernel/kheaders.md5|tail -1)" == "$tarfile_md5" ]; then
exit
fi
if [ "${quiet}" != "silent_" ]; then
echo " GEN $tarfile"
fi
rm -rf $cpio_dir
mkdir $cpio_dir
pushd $kroot > /dev/null
for f in $src_file_list;
do find "$f" ! -name "*.cmd" ! -name ".*";
done | cpio --quiet -pd $cpio_dir
popd > /dev/null
# The second CPIO can complain if files already exist which can
# happen with out of tree builds. Just silence CPIO for now.
for f in $obj_file_list;
do find "$f" ! -name "*.cmd" ! -name ".*";
done | cpio --quiet -pd $cpio_dir >/dev/null 2>&1
# Remove comments except SDPX lines
find $cpio_dir -type f -print0 |
xargs -0 -P8 -n1 perl -pi -e 'BEGIN {undef $/;}; s/\/\*((?!SPDX).)*?\*\///smg;'
tar -Jcf $tarfile -C $cpio_dir/ . > /dev/null
echo "$src_files_md5" > kernel/kheaders.md5
echo "$obj_files_md5" >> kernel/kheaders.md5
echo "$(md5sum $tarfile | cut -d ' ' -f1)" >> kernel/kheaders.md5
rm -rf $cpio_dir