Messages in this thread | | | Date | Wed, 01 Oct 2008 11:36:27 -0700 | From | Jeremy Fitzhardinge <> | Subject | Re: [RFC] CPUID usage for interaction between Hypervisors and Linux. |
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H. Peter Anvin wrote: > With a sufficiently large block, we could use fixed points, e.g. by > having each vendor create interfaces in the 0x40SSSSXX range, where > SSSS is the PCI ID they use for PCI devices.
Sure, you could do that, but you'd still want to have a signature in 0x40SSSS00 to positively identify the chunk. And what if you wanted more than 256 leaves?
> Note that I said "create interfaces". It's important that all about > this is who specified the interface -- for "what hypervisor is this" > just use 0x40000000 and disambiguate based on that.
"What hypervisor is this?" isn't a very interesting question; if you're even asking it then it suggests that something has gone wrong. Its much more useful to ask "what interfaces does this hypervisor support?", and enumerating a smallish range of well-known leaves looking for signatures is the simplest way to do that. (We could use signatures derived from the PCI vendor IDs which would help with managing that namespace.)
J
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