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Date: Tue, 9 Nov 2010 14:48:16 +0100 From: Andi Kleen <andi@...stfloor.org> To: Michael Matz <matz@...e.de> Cc: Dave Korn <dave.korn.cygwin@...il.com>, Andi Kleen <andi@...stfloor.org>, Richard Guenther <richard.guenther@...il.com>, Andreas Schwab <schwab@...ux-m68k.org>, Jim <jim876@...all.nl>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, gcc@....gnu.org Subject: Re: gcc 4.5.1 / as 2.20.51.0.11 miscompiling drivers/char/i8k.c ? > My speculation is, that the asm is not removed but rather that regs.eax > isn't reloaded after the asm because the memory clobber doesn't clobber > automatic variables. Yes that makes sense. I wasn't able to verify it so far though. Maybe the original poster could try the obvious patch instead of the volatile change. i8k: tell gcc that regs gets clobbered Signed-off-by: Andi Kleen <ak@...ux.intel.com> diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c index 3bc0eef..f3bbf73 100644 --- a/drivers/char/i8k.c +++ b/drivers/char/i8k.c @@ -142,7 +142,7 @@ static int i8k_smm(struct smm_regs *regs) "lahf\n\t" "shrl $8,%%eax\n\t" "andl $1,%%eax\n" - :"=a"(rc) + :"=a"(rc), "=m" (*regs) : "a"(regs) : "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory"); #else @@ -167,7 +167,7 @@ static int i8k_smm(struct smm_regs *regs) "movl %%edx,0(%%eax)\n\t" "lahf\n\t" "shrl $8,%%eax\n\t" - "andl $1,%%eax\n":"=a"(rc) + "andl $1,%%eax\n":"=a"(rc), "=m" (*regs) : "a"(regs) : "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory"); #endif -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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