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

[Anthony Liguori <anthony@codemonkey.ws>]

On 01/06/2010 07:54 AM, 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?

Yeah, I'm not sure I can think of a better way.

Regards,

Anthony Liguori