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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-07-12 11:25:04 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-07-12 11:25:04 -0700 |
| commit | a137802ee839ace40079bebde24cfb416f73208a (patch) | |
| tree | db6e93c3d1c9f5808a2d78fcf91fe96260eb786b | |
| parent | 8b9f2caa02e96bb92327e3b4557adbb3f1203dc7 (diff) | |
| download | lwn-a137802ee839ace40079bebde24cfb416f73208a.tar.gz lwn-a137802ee839ace40079bebde24cfb416f73208a.zip | |
Don't use '-fwrapv' compiler option: it's buggy in gcc-4.1.x
This causes kernel images that don't run init to completion with certain
broken gcc versions.
This fixes kernel bugzilla entry:
http://bugzilla.kernel.org/show_bug.cgi?id=13012
I suspect the gcc problem is this:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28230
Fix the problem by using the -fno-strict-overflow flag instead, which
not only does not exist in the known-to-be-broken versions of gcc (it
was introduced later than fwrapv), but seems to be much less disturbing
to gcc too: the difference in the generated code by -fno-strict-overflow
are smaller (compared to using neither flag) than when using -fwrapv.
Reported-by: Barry K. Nathan <barryn@pobox.com>
Pushed-by: Frans Pop <elendil@planet.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | Makefile | 2 |
1 files changed, 1 insertions, 1 deletions
@@ -565,7 +565,7 @@ KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,) KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,) # disable invalid "can't wrap" optimizations for signed / pointers -KBUILD_CFLAGS += $(call cc-option,-fwrapv) +KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow) # revert to pre-gcc-4.4 behaviour of .eh_frame KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm) |