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SubjectRe: [PATCH] Use correct byte-sized register constraint in __xchg_op()
PIng?

On 04/02/2012 04:15 PM, Jeremy Fitzhardinge wrote:
> x86-64 can access the low half of any register, but i386 can only do
> it with a subset of registers. 'r' causes compilation failures on i386,
> but 'q' expresses the constraint properly.
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
> Reported-by: Leigh Scott <leigh123linux@googlemail.com>
> Tested-by: Thomas Reitmayr <treitmayr@devbase.at>
>
> diff --git a/arch/x86/include/asm/cmpxchg.h b/arch/x86/include/asm/cmpxchg.h
> index b3b7332..bc18d0e 100644
> --- a/arch/x86/include/asm/cmpxchg.h
> +++ b/arch/x86/include/asm/cmpxchg.h
> @@ -43,7 +43,7 @@ extern void __add_wrong_size(void)
> switch (sizeof(*(ptr))) { \
> case __X86_CASE_B: \
> asm volatile (lock #op "b %b0, %1\n" \
> - : "+r" (__ret), "+m" (*(ptr)) \
> + : "+q" (__ret), "+m" (*(ptr)) \
> : : "memory", "cc"); \
> break; \
> case __X86_CASE_W: \
>
>
> --
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