[libvirt] [Qemu-devel] libvirt<->QEMU interfaces for CPU models

[Eduardo Habkost]

On Fri, Mar 01, 2013 at 07:31:46PM +0100, Andreas Färber wrote:
> Am 01.03.2013 14:12, schrieb Jiri Denemark:
> > On Thu, Feb 21, 2013 at 11:58:18 -0300, Eduardo Habkost wrote:
> >> = Listing CPU models =
> >>
> >> Requirement: libvirt needs to know which CPU models are available to be used
> >> with the "-cpu" option.
> >>
> >> Current problem: libvirt relies on help output parsing for that.
> 
> query-cpu-definitions is the QMP command to retrieve values compatible
> with -cpu.
> 
> And if libvirt is not using it, I really don't understand why the work
> of maintaining this crappy interface has been pushed onto us in the
> first place? There is no reuse between -cpu ? and QMP implementations so
> it's just extra work, there is no communicated or implemented way to
> extend the arch_query_cpu_definitions() implementation to become more
> usable for command line output implementation (e.g., associating a PVR
> value with the model name for ppc) and, while we're at it, it uses
> global functions plus a stub rather than a CPUState hook with a no-op
> default implementation in qom/cpu.c...

I have the same questions you have.  :-)

But my main complaint about query-cpu-definitions is not about the
implementation: it's that the interface was introduced without taking
into account the requirements of libvirt regarding CPU features. It was
found to be not appropriate for what libvirt needs[1], but somehow it
got applied anyway.

[1] http://article.gmane.org/gmane.comp.emulators.qemu/164772

-- 
Eduardo