Re: [Qemu-devel] [PATCH] RFC: powerpc: add PVR compatibility check

[Alexander Graf]

Am 05.11.2013 um 05:00 schrieb Paul Mackerras <address@hidden>:

> On Mon, Nov 04, 2013 at 10:05:58AM +0100, Alexander Graf wrote:
>> 
>> Yeah, we really need to check that guest vpcu == host vcpu for HV KVM.
> 
> In general I agree, but the one difficulty I see is that a check for
> exact equality will interact badly with qemu's habit of picking a
> specific processor version when the user specifies something general
> like "POWER7".  So if the user does -cpu POWER7 on a machine with
> (for example) a POWER7 v2.1 processor, but qemu arbitrarily picks the
> PVR for POWER7 v2.3, then it will fail, which will be completely
> puzzling to the user -- "I asked for POWER7, and it is a POWER7,
> what's the problem??".
> 
> Maybe if the user asks for a non-specific processor type, and the
> host's PVR matches the request, then qemu should take the host's PVR
> rather than just picking some arbitrary processor version.

Yup.

Alex