Messages in this thread Patch in this message | | | Date | Tue, 9 Nov 2010 14:48:16 +0100 | From | Andi Kleen <> | Subject | Re: gcc 4.5.1 / as 2.20.51.0.11 miscompiling drivers/char/i8k.c ? |
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> 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@linux.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
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