Re: [Qemu-devel] [uq/master PATCH 0/7] x86 CPU subclasses, take 7

[Eduardo Habkost]

On Fri, Jan 31, 2014 at 05:52:57PM +0100, Paolo Bonzini wrote:
> Il 31/01/2014 17:42, Eduardo Habkost ha scritto:
> >>> It looks like only -device would be able to create actual CPU models,
> >>> but for -device to work we need as minimum this series and conversion
> >>> of CPU features to properties in tree. Then I guess we can override
> >>> cannot_instantiate_with_device_add_yet for x86 CPUs.
> >Setting cannot_instantiate_with_device_add_yet=false looks much simpler
> >than implementing UserCreatable. My question is: may we do that, already
> >(once this series gets included), or is there something else holding us
> >from doing it?
> 
> Once you make something creatable with "-object", the API must not
> change anymore.  So we would have to think twice about that.
> 
> Allowing -device may be okay, since in the (very?) long term -device
> can be replaced by -object.  But -object is definitive.

OK, one additional reason to try device_add first.

But then we have one additional problem:

 * We want to allow libvirt to probe for CPU model information when
   running QEMU using "-machine none" (because libvirt already does
   that, and we don't want to require libvirt to run QEMU multiple
   times)
 * "device_add driver=<model>-x86_64-cpu" requires an icc-bus to be present
 * -machine none doesn't have any bus
 * I don't see a way to create an icc-bus through QMP (is there a way?)

-- 
Eduardo