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Subject[PATCH,v2] Only add '-fwrapv' to gcc CFLAGS for gcc 4.2 and later
On Friday 10 July 2009, Frans Pop wrote:
> The discussion on issue looks to have died, but it has bitten Debian
> stable ("Lenny") [1] as it causes init to die on s390 after a kernel
> update.
> Here's a possible patch. The exact gcc version to check for is still a
> bit open I guess. For the s390 issue I've confirmed that 4.2.4 is OK,
> but for safety and because of Andrew's comment above I've set the test
> for 4.3 in the patch.

Here's an updated patch as I found the gcc version check was incorrect
(0430 should have been 0403; sorry).

I've now changed the check to allow -fwrapv for gcc 4.2 as that has been
shown to work and because of the consideration mentioned in my previous

From: Frans Pop <>
Subject: Only add '-fwrapv' to gcc CFLAGS for gcc 4.2 and later

This flag has been shown to cause init to segfault for kernels
compiled with gcc-4.1. gcc version 4.2.4 has been shown to be OK.

This fixes

Reported-by: Barry K. Nathan <>
Signed-off-by: Frans Pop <>

diff --git a/Makefile b/Makefile
index 0aeec59..2519fde 100644
--- a/Makefile
+++ b/Makefile
@@ -565,7 +565,8 @@ KBUILD_CFLAGS += $(call
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 += $(shell if [ $(call cc-version) -ge 0402 ]; then \
+ echo $(call cc-option,-fwrapv); fi ;)

# revert to pre-gcc-4.4 behaviour of .eh_frame
KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm)

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