Re: [Qemu-devel] [PATCH v4 7/8] qmp: Support abstract classes on device-list-properties

[Eduardo Habkost]

On Fri, Nov 11, 2016 at 01:17:44PM +0100, Jiri Denemark wrote:
> On Tue, Nov 08, 2016 at 08:29:41 +0100, Markus Armbruster wrote:
> > Eduardo Habkost <address@hidden> writes:
> > > libvirt wants to know if the QEMU binary supports a given -cpu
> > > option (normally CPU features that can be enabled/disabled using
> > > "+foo"/"-foo").
> > 
> > The obvious way to check whether a specific CPU supports it is to
> > introspect that CPU.
> > 
> > The obvious way to check whether all CPUs of interest support it
> > (assuming that is a productive question) is to introspect all CPUs of
> > interest.  Works regardless of whether the option is inherited, which is
> > really an implementation detail.
> 
> As Eduardo said, libvirt wants to know whether it can use a given CPU
> feature with current QEMU binary. In -cpu help, we can see a list of
> models and features QEMU understands, but we need to get similar info
> via QMP. CPU models are easy, but how do we get the list of CPU
> features? If introspection is the way to get it, I'm fine with that,
> just beware that we don't actually know the name of the CPU object
> (Westmere-x86_64-cpu), we only know the name of the CPU model
> (Westmere). So if the object name is needed, we need to query the
> mapping from CPU model names to CPU object names.

I have patches to add the QOM type name to query-cpu-definitions.
I don't remember if I submitted them to qemu-devel already. I
will check.

-- 
Eduardo