diff options
author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2018-02-28 20:17:37 +0100 |
---|---|---|
committer | Masahiro Yamada <yamada.masahiro@socionext.com> | 2018-03-05 15:48:29 +0100 |
commit | 638e69cf2230737655fcb5ee9879c2fab7679187 (patch) | |
tree | 09ea3453999ea8693a09aaa28aa0c94bf45f6ae8 /scripts/kconfig/Makefile | |
parent | fixdep: remove some false CONFIG_ matches (diff) | |
download | linux-638e69cf2230737655fcb5ee9879c2fab7679187.tar.xz linux-638e69cf2230737655fcb5ee9879c2fab7679187.zip |
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/kconfig/Makefile')
0 files changed, 0 insertions, 0 deletions