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

[Avi Kivity]

On 12/22/2009 06:12 PM, Anthony Liguori wrote:
> I think the only two Fully Correct approachs are to support a very 
> specific CPU (e.g. Xeon-X5270) or provide the ability to individually 
> tweak cpu flags.

Yes.  By a curious coincidence these are what the hardware vendors 
define (unlike compat classes etc.).

> The notion of compatibility classes should probably be left to 
> management tools.  We can make it a lot easier for them though by 
> supporting turning point CPU models.

Agreed.

> For instance, Xeon-X5570 should be a least common denominator for 
> Nehalem processors.  It's probably better for users too.  It's easier 
> for them to answer "do I have anything older than a Xeon-X5570" than 
> to ask "do I have any Woodcrest class processors".
>
> I encounter this confusion a lot.  I usually ask people whether they 
> have a Nehalem processor when debugging something and their response 
> is always, I have a Xeon-XYZ, is that Nehalem?

This is complicated by the fact that processors don't have straight-line 
development, and that marketing names don't correspond to anything.  For 
example Xeon can be any of the Pentium 4, Core, Core 2, and Nehalem (and 
perhaps other) microachitectures.  A newer Xeon is often introduced with 
an older core (usually for larger machines) than previously existing Xeons.

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error compiling committee.c: too many arguments to function