On 4/24/2021 11:50 PM, Masahiro Yamada wrote:
On Sat, Apr 24, 2021 at 2:02 AM Elliot Berman <eberman@xxxxxxxxxxxxxx> wrote: Sorry for the delay.
No problem!
This patch is over-engineering.
I thought so, too.
I will apply this. https://patchwork.kernel.org/project/linux-kbuild/patch/20210425062407.1183801-5-masahiroy@xxxxxxxxxx/ The 'cmp' command is not expensive. md5sum is unneeded.
Thanks!
If you update the timestamp of KCONFIG_CONFIG without actually changing anything, config_data.gz is re-generated and causes vmlinux to re-link. When Link Time Optimization is enabled, unnecessary re-linking of vmlinux is highly desirable since it adds several minutes to build time. Avoid touching config_data.gz by using a script to compare the existing config_data.gz, KCONFIG_CONFIG, or script itself to update only if any is mismatched. The script follows gen_kheaders.sh approach for determing in update is needed. The script intentionally avoids re-compressing KCONFIG_CONFIG. The .config can be touched, for instance, by a build script which installs the default defconfig and then applies a defconfig fragment on top. For a simple example on my x86 machine, I modified x86 default defconfig to set CONFIG_IKCONFIG=y and run: make -j50 defconfig tiny.config vmlinux make -j50 defconfig tiny.config vmlinux With this patch, vmlinux is not re-built as a result of config_data.gz change. Changes in v2: - Use md5 checksum to compare .config instead of gzip'ing again Signed-off-by: Elliot Berman <eberman@xxxxxxxxxxxxxx> --- kernel/.gitignore | 1 + kernel/Makefile | 4 +++- kernel/gen_config_data.sh | 31 +++++++++++++++++++++++++++++++ 3 files changed, 35 insertions(+), 1 deletion(-) create mode 100755 kernel/gen_config_data.sh diff --git a/kernel/.gitignore b/kernel/.gitignore index 78701ea..a191136 100644 --- a/kernel/.gitignore +++ b/kernel/.gitignore @@ -1,4 +1,5 @@ # SPDX-License-Identifier: GPL-2.0-only +config_data.gz.md5 kheaders.md5 timeconst.h hz.bc diff --git a/kernel/Makefile b/kernel/Makefile index 320f1f3..0784bf3d 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -139,8 +139,10 @@ obj-$(CONFIG_SCF_TORTURE_TEST) += scftorture.o $(obj)/configs.o: $(obj)/config_data.gz targets += config_data.gz +quiet_cmd_genicfg = CHK $(obj)/config_data.gz + cmd_genicfg = $(CONFIG_SHELL) $(srctree)/kernel/gen_config_data.sh $@ $< $(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE - $(call if_changed,gzip) + $(call cmd,genicfg) $(obj)/kheaders.o: $(obj)/kheaders_data.tar.xz diff --git a/kernel/gen_config_data.sh b/kernel/gen_config_data.sh new file mode 100755 index 00000000..e9ff193 --- /dev/null +++ b/kernel/gen_config_data.sh @@ -0,0 +1,31 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 + +# This script generates a compressed version of .config, if its checksum has changed +set -e + +this_file="$(readlink -f "$0")" +outfile=$1 +infile=$2 + +config_md5="$(md5sum $infile | cut -d ' ' -f1)" +# Any changes to this script will also cause a rebuild of config_data. +this_file_md5="$(md5sum $sfile | cut -d ' ' -f1)" +if [ -f $outfile ]; then outfile_md5="$(md5sum $outfile | cut -d ' ' -f1)"; fi + +if [ -f $outfile.md5 ] && + [ "$(head -n 1 $outfile.md5)" = "$config_md5" ] && + [ "$(head -n 2 $outfile.md5 | tail -n 1)" = "$this_file_md5" ] && + [ "$(tail -n 1 $outfile.md5)" = "$outfile_md5" ]; then + exit +fi + +if [ "${quiet}" != "silent_" ]; then + echo " GEN $outfile" +fi + +${KGZIP} -c -n -f -9 $infile > $outfile + +echo "$config_md5" > $outfile.md5 +echo "$this_file_md5" >> $outfile.md5 +echo "$(md5sum $outfile | cut -d ' ' -f1)" >> $outfile.md5 -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
