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| author | Masahiro Yamada <masahiroy@kernel.org> | 2021-04-25 15:24:07 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-05-11 14:04:16 +0200 |
| commit | 79c95130a52adcf999ba5c62b638666266d43385 (patch) | |
| tree | f0accb898ea0530295a5438a7c4b023da7b6aa9b | |
| parent | 19c8c34a8b80a555b4226681f2e4bca8628e4822 (diff) | |
| download | linux-stable-79c95130a52adcf999ba5c62b638666266d43385.tar.gz linux-stable-79c95130a52adcf999ba5c62b638666266d43385.tar.bz2 linux-stable-79c95130a52adcf999ba5c62b638666266d43385.zip | |
kbuild: update config_data.gz only when the content of .config is changed
commit 46b41d5dd8019b264717978c39c43313a524d033 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/.gitignore | 1 | ||||
| -rw-r--r-- | kernel/Makefile | 9 |
2 files changed, 8 insertions, 2 deletions
diff --git a/kernel/.gitignore b/kernel/.gitignore index 34d1e77ee9df..0f0dba6c1eed 100644 --- a/kernel/.gitignore +++ b/kernel/.gitignore @@ -1,4 +1,5 @@ # +/config_data # Generated files # kheaders.md5 diff --git a/kernel/Makefile b/kernel/Makefile index 6aef13053a5c..d038b0de886e 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -122,10 +122,15 @@ KCOV_INSTRUMENT_stackleak.o := n $(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 |