Re: [Qemu-devel] cpuid problem in upstream qemu with kvm

[Alexander Graf]

On 06.01.2010, at 14:54, Avi Kivity wrote:

> On 01/06/2010 03:49 PM, Anthony Liguori wrote:
>>> 
>>>> 
>>>> I think that's workable but I think there may be some subtle issues 
>>>> especially across qemu versions.  Can you give an example of what you 
>>>> would expect the output to be?
>>> 
>>> -> { command: query-cpu-capabalities }
>>> <- { result: { features: [vm, fpu, lm, sse2, sse3, sssse3, ssssssse3, 
>>> sse3.14 ], cache: { ... }, vendor: { .... }, etc. } }
>>> 
>>> Or something.  We'd need similar queries for the number of PCI slots, for 
>>> example, so the GUI can tell the user when adding hardware is no longer an 
>>> option instead of trying it blindly and returning an error.
>> 
>> 
>> Yeah, the trick with this is that we don't have such a thing as a bare bones 
>> CPU in qemu right now.
>> 
>> So you can't really say -cpu qemu64+vm+fpu+lm....
>> 
>> Because some extra features might sneak in.  What I'm getting at is that we 
>> need a way to make the results of this command translate into a -cpu 
>> invocation that works reliably across multiple versions of qemu.
> 
> Well, we can freeze qemu64 if we wish.  That's still not 100% accurate since 
> kvm can remove features from qemu64.
> 
> -cpu none,+flags,vendor=foo,cache=bar,ad=nauseum?

I'd rather add a "kvm" cpu and leave the qemu64 one to qemu tcg features.

Alex