New CPUID/MSR driver; virtualization hooks
H. Peter Anvin
hpa at zytor.com
Thu Apr 5 14:59:34 PDT 2007
Jeremy Fitzhardinge wrote:
> Zachary Amsden wrote:
>> Or implement anything useful at all ... perhaps it might be useful to
>> simply wrap them with an -ENOSYS in some cases.
>> Rusty, Jeremy. Chris - any feedback on MSR support?
> I've looked at hpa's patch a bit, but I don't quite get what the point
> is yet. Is it that rdmsr/wrmsr can use multiple random registers, so
> its necessary to haul them all around? And that cpuid might use more
> beyond the current eax-edx?
Yes, pretty much. There are enough evidence that you can't trust CPU
architecture to stay sane. Inside Transmeta it was a constant battle,
and we were a small company.
> Xen will trap and emulate any rd/wrmsr instructions, so I don't think it
> needs anything beyond native support.
If that's true for all hypervisors, then that's obviously the easiest
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