On 04/23/2010 10:22 PM, Jeremy Fitzhardinge wrote:
On 04/23/2010 02:34 AM, Avi Kivity wrote:
diff -rup a/time-warp-test.c b/time-warp-test.c
--- a/time-warp-test.c 2010-04-15 16:30:13.955981607 -1000
+++ b/time-warp-test.c 2010-04-15 16:35:37.777982377 -1000
@@ -91,7 +91,7 @@ static inline unsigned long long __rdtsc
{
DECLARE_ARGS(val, low, high);
- asm volatile("cpuid; rdtsc" : EAX_EDX_RET(val, low, high));
+ asm volatile("cpuid; rdtsc" : EAX_EDX_RET(val, low, high) ::
"ebx", "ecx");
Plus, replace cpuid by lfence/mfence. cpuid will trap.
I presume the clobbers are needed for cpuid; if you use [lm]fence then
they shouldn't be needed, right?
Right. But I'm not sure lfence/mfence are sufficient - from what I
understand rdtsc can pass right through them.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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