releases/2.6.27.27/don-t-use-fwrapv-compiler-option-it-s-buggy-in-gcc-4.1.x.patch

   1 From a137802ee839ace40079bebde24cfb416f73208a Mon Sep 17 00:00:00 2001
   2 From: Linus Torvalds <torvalds@linux-foundation.org>
   3 Date: Sun, 12 Jul 2009 11:25:04 -0700
   4 Subject: Don't use '-fwrapv' compiler option: it's buggy in gcc-4.1.x
   5
   6 From: Linus Torvalds <torvalds@linux-foundation.org>
   7
   8 commit a137802ee839ace40079bebde24cfb416f73208a upstream.
   9
  10 This causes kernel images that don't run init to completion with certain
  11 broken gcc versions.
  12
  13 This fixes kernel bugzilla entry:
  14         http://bugzilla.kernel.org/show_bug.cgi?id=13012
  15
  16 I suspect the gcc problem is this:
  17         http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28230
  18
  19 Fix the problem by using the -fno-strict-overflow flag instead, which
  20 not only does not exist in the known-to-be-broken versions of gcc (it
  21 was introduced later than fwrapv), but seems to be much less disturbing
  22 to gcc too: the difference in the generated code by -fno-strict-overflow
  23 are smaller (compared to using neither flag) than when using -fwrapv.
  24
  25 Reported-by: Barry K. Nathan <barryn@pobox.com>
  26 Pushed-by: Frans Pop <elendil@planet.nl>
  27 Cc: Andrew Morton <akpm@linux-foundation.org>
  28 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  30
  31 ---
  32  Makefile |    2 +-
  33  1 file changed, 1 insertion(+), 1 deletion(-)
  34
  35 --- a/Makefile
  36 +++ b/Makefile
  37 @@ -557,7 +557,7 @@ KBUILD_CFLAGS += $(call cc-option,-Wdecl
  38  KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,)
  39
  40  # disable invalid "can't wrap" optimzations for signed / pointers
  41 -KBUILD_CFLAGS  += $(call cc-option,-fwrapv)
  42 +KBUILD_CFLAGS  += $(call cc-option,-fno-strict-overflow)
  43
  44  # Add user supplied CPPFLAGS, AFLAGS and CFLAGS as the last assignments
  45  # But warn user when we do so