RE: [RFC] CPUID usage for interaction between Hypervisors and Linux.

[Nakajima, Jun]

On 10/3/2008 5:35:39 PM, H. Peter Anvin wrote:
> Nakajima, Jun wrote:
> >
> > What's the significance of supporting multiple interfaces to the
> > same guest simultaneously, i.e. _runtime_? We don't want the guests
> > to run on such a literarily Frankenstein machine. And practically,
> > such testing/debugging would be good only for Halloween :-).
> >
>
> By that notion, EVERY CPU currently shipped is a "Frankenstein" CPU,
> since at very least they export Intel-derived and AMD-derived interfaces.
>  This is in other words, a ridiculous claim.

The big difference here is that you could create a VM at runtime (by combining the existing interfaces) that did not exist before (or was not tested before). For example, a hypervisor could show hyper-v, osx-v (if any), linux-v, etc., and a guest could create a VM with hyper-v MMU, osx-v interrupt handling, Linux-v timer, etc. And such combinations/variations can grow exponentially.

Or are you suggesting that multiple interfaces be _available_ to guests at runtime but the guest chooses one of them?

>         -hpa
>
             .
Jun Nakajima | Intel Open Source Technology Center
èº{.nÇ+‰·Ÿ®‰­†+%ŠËlzwm…ébëæìr¸›zX§»®w¥Š{ayºÊÚë,j­¢f£¢·hš‹àz¹®w¥¢¸¢·¦j:+v‰¨ŠwèjØm¶Ÿÿ¾«‘êçzZ+ƒùšŽŠÝj"ú!¶iO•æ¬z·švØ^¶m§ÿðÃnÆàþY&—