path: root/scripts/Makefile.lib
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authorRasmus Villemoes <linux@rasmusvillemoes.dk>2018-02-28 20:17:37 +0100
committerMasahiro Yamada <yamada.masahiro@socionext.com>2018-03-05 23:48:29 +0900
commit638e69cf2230737655fcb5ee9879c2fab7679187 (patch)
tree09ea3453999ea8693a09aaa28aa0c94bf45f6ae8 /scripts/Makefile.lib
parent5b8ad96d1a4421ffe417e647a65064aad1e84fb4 (diff)
fixdep: do not ignore kconfig.h
kconfig.h was excluded from consideration by fixdep by 6a5be57f0f00 (fixdep: fix extraneous dependencies) to avoid some false positive hits (1) include/config/.h (2) include/config/h.h (3) include/config/foo.h (1) occurred because kconfig.h contains the string CONFIG_ in a comment. However, since dee81e988674 (fixdep: faster CONFIG_ search), we have a check that the part after CONFIG_ is non-empty, so this does not happen anymore (and CONFIG_ appears by itself elsewhere, so that check is worthwhile). (2) comes from the include guard, __LINUX_KCONFIG_H. But with the previous patch, we no longer match that either. That leaves (3), which amounts to one [1] false dependency (aka stat() call done by make), which I think we can live with: We've already had one case [2] where the lack of include/linux/kconfig.h in the .o.cmd file caused a missing rebuild, and while I originally thought we should just put kconfig.h in the dependency list without parsing it for the CONFIG_ pattern, we actually do have some real CONFIG_ symbols mentioned in it, and one can imagine some translation unit that just does '#ifdef __BIG_ENDIAN' but doesn't through some other header actually depend on CONFIG_CPU_BIG_ENDIAN - so changing the target endianness could end up rebuilding the world, minus that small TU. Quoting Linus, ... when missing dependencies cause a missed re-compile, the resulting bugs can be _really_ subtle. [1] well, two, we now also have CONFIG_BOOGER/booger.h - we could change that to FOO if we care [2] https://lkml.org/lkml/2018/2/22/838 Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Diffstat (limited to 'scripts/Makefile.lib')
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