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

[Dor Laor]

On 12/22/2009 12:51 AM, john cooper wrote:
> Dor Laor wrote:
>
> > Qemu will check the required cpuid of the cpu model on the host and
> > refuse to load otherwise. When moving to this model, migration can be
> > simplified too since there are fewer combination, and one can choose
> > performance over migration flexibility and wise versa.
> > Due to the above check, the destination qemu won't load if the host
> > does not support its cpu model.
>
> If you're referring to the check in my patch, that's
> currently advisory only.
>
> The existing cpu model encoding of CPUID tosses flags
> in to the soup on speculation they may be available
> on the host. If not it assumes they will be quietly
> disabled on their way to the guest along with whatever

why not shout loudly and abort? Do you want windows to reactivate itself?

> flags were enabled via +<flag> on the command line.
> This mixed treatment for model implied vs. user
> specified flags could be partly an artifact of trying
> to adapt the legacy qemu64 model to whatever host
> silicon it finds itself upon.
>
> -john