path: root/Makefile
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authorMasahiro Yamada <>2021-04-25 15:24:07 +0900
committerMasahiro Yamada <>2021-05-02 00:43:35 +0900
commit46b41d5dd8019b264717978c39c43313a524d033 (patch)
tree00e792005c14b5ad16f126dbec4e2f2201745505 /Makefile
parent40cb020305f40bafc2a13c7e879a33dbbd607507 (diff)
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 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/ CALL scripts/atomic/ CHK include/generated/compile.h CHK include/generated/autoksyms.h Reported-by: Elliot Berman <> Signed-off-by: Masahiro Yamada <>
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