Nakajima, Jun wrote: > 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? > The guest chooses what it wants to use. We already do this: for example, we use CPUID leaf 0x80000006 preferentially to CPUID leaf 2, simply because it is a better interface. And you're absolutely right that the guest may end up picking and choosing different parts of the interfaces. That's how it is supposed to work. -hpa _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
