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| author | Masahiro Yamada <masahiroy@kernel.org> | 2021-04-25 08:24:07 +0200 |
|---|---|---|
| committer | Masahiro Yamada <masahiroy@kernel.org> | 2021-05-01 17:43:35 +0200 |
| commit | 46b41d5dd8019b264717978c39c43313a524d033 (patch) | |
| tree | 00e792005c14b5ad16f126dbec4e2f2201745505 /kernel/Makefile | |
| parent | .gitignore: ignore only top-level modules.builtin (diff) | |
| download | linux-46b41d5dd8019b264717978c39c43313a524d033.tar.xz linux-46b41d5dd8019b264717978c39c43313a524d033.zip | |
kbuild: update config_data.gz only when the content of .config is changed
If the timestamp of the .config file is updated, config_data.gz is
regenerated, then vmlinux is re-linked. This occurs even if the content
of the .config has not changed at all.
This issue was mitigated by commit 67424f61f813 ("kconfig: do not write
.config if the content is the same"); Kconfig does not update the
.config when it ends up with the identical configuration.
The issue is remaining when the .config is created by *_defconfig with
some config fragment(s) applied on top.
This is typical for powerpc and mips, where several *_defconfig targets
are constructed by using merge_config.sh.
One workaround is to have the copy of the .config. The filechk rule
updates the copy, kernel/config_data, by checking the content instead
of the timestamp.
With this commit, the second run with the same configuration avoids
the needless rebuilds.
$ make ARCH=mips defconfig all
[ snip ]
$ make ARCH=mips defconfig all
*** Default configuration is based on target '32r2el_defconfig'
Using ./arch/mips/configs/generic_defconfig as base
Merging arch/mips/configs/generic/32r2.config
Merging arch/mips/configs/generic/el.config
Merging ./arch/mips/configs/generic/board-boston.config
Merging ./arch/mips/configs/generic/board-ni169445.config
Merging ./arch/mips/configs/generic/board-ocelot.config
Merging ./arch/mips/configs/generic/board-ranchu.config
Merging ./arch/mips/configs/generic/board-sead-3.config
Merging ./arch/mips/configs/generic/board-xilfpga.config
#
# configuration written to .config
#
SYNC include/config/auto.conf
CALL scripts/checksyscalls.sh
CALL scripts/atomic/check-atomics.sh
CHK include/generated/compile.h
CHK include/generated/autoksyms.h
Reported-by: Elliot Berman <eberman@codeaurora.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'kernel/Makefile')
| -rw-r--r-- | kernel/Makefile | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/Makefile b/kernel/Makefile index e8a6715f38dc..4df609be42d0 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -142,10 +142,15 @@ obj-$(CONFIG_SCF_TORTURE_TEST) += scftorture.o $(obj)/configs.o: $(obj)/config_data.gz -targets += config_data.gz -$(obj)/config_data.gz: $(KCONFIG_CONFIG) FORCE +targets += config_data config_data.gz +$(obj)/config_data.gz: $(obj)/config_data FORCE $(call if_changed,gzip) +filechk_cat = cat $< + +$(obj)/config_data: $(KCONFIG_CONFIG) FORCE + $(call filechk,cat) + $(obj)/kheaders.o: $(obj)/kheaders_data.tar.xz quiet_cmd_genikh = CHK $(obj)/kheaders_data.tar.xz |