Re: questions about rd{msr|tsc|pmc} instruction with x86-64

From: Jike Song
Date: Thu Oct 16 2008 - 12:31:31 EST


On Thu, Oct 16, 2008 at 2:39 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> Jike Song wrote:
>> {snip}
>
> "A" means rdx:rax on x86-64, not edx:eax. For a 64-bit number, it means,
> literally, "one of rdx or rax"! As you correctly point out, this is not how
> rdmsr works.
>
> -hpa
>

Thanks, Peter! So I misunderstood the gcc constraint 'A' for x86-64,
but seems the comment "while x86_64 returns at rax" still wrong,
should this be fixed?

--
Thanks,
Jike
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