On Fri, Aug 7, 2020 at 4:28 PM Alexander Graf <graf@xxxxxxxxxx> wrote:
>
>
>
> On 04.08.20 06:20, Aaron Lewis wrote:
> > + __asm__ __volatile__("rdmsr_start: rdmsr; rdmsr_end:" :
> > + "=a"(a), "=d"(d) : "c"(msr) : "memory");
>
> I personally would find
>
> asm volatile("rdmsr_start:");
> r = rdmsr(msr);
> asm volatile("rdmsr_end:");
>
> more readable. Same for wrmsr.
I don't think the suggested approach is guaranteed to work, because "r
= rdmsr(msr)" isn't always going to be a single instruction. The
compiler may do some register shuffling before and/or after the rdmsr
instruction itself, and I believe Aaron wants the labels immediately
before and after the rdmsr instruction.
