[libvirt] CPU Support

[Eduardo Habkost]

CCing the AMD people who worked on this.

On Wed, Jul 18, 2018 at 12:18:45PM +0200, Pavel Hrdina wrote:
> On Wed, Jul 18, 2018 at 10:50:34AM +0100, Daniel P. Berrangé wrote:
> > On Wed, Jul 18, 2018 at 12:41:48PM +0300, Hetz Ben Hamo wrote:
> > > Hi,
> > > 
> > > I've been looking at the CPU list and although I see lots of CPU's, I
> > > cannot find 2 CPU families:
> > > 
> > > * AMD Ryzen
> > > * AMD Threadripper
> > > 
> > > Although EPYC has been added recently.
> > > 
> > > Are there any missing details which preventing adding those CPU's to the
> > > list?
> > 
> > Libvirt adds CPU models based on what QEMU supports. So from libvirt side the
> > answer is simply that QEMU doesn't expose any models for Ryzen/Threadripper,
> > but I'm not clear why it doesn't...
> > 
> > For a while I thought Ryzen/Threadripper would have same feature set as
> > EPYC, but I've seen bugs recently suggesting that is not in fact the
> > case. So it does look like having those models exposed by QEMU might
> > be useful.
> > 
> > Copy'ing QEMU devel & the CPU model maintainers for opinions.
> 
> I think that QEMU should figure out some pattern for naming CPU models
> because it's one big mess.  EPYC and Ryzen are bad names for QEMU as
> Core/Xeon would be for Intel CPUs.  It's the name of a model families
> and it will probably remain the same but with different
> microarchitecture.
> 
> Better name would be similarly like for the latest Inter CPUs,
> Skylake-Client and Skylake-Server.  Currently AMD has already two
> microarchitectures, Zen and Zen+ and there is third one Zen 2 planned.
> 
> Zen has AMD Ryzen, AMD Ryzen Threadripper and AMD Epyc.
> Zen+ has AMD Ryzen, AMD Ryzen Threadripper
> 
> And I bet that Zen 2 will follow the same model families.
> 
> We probably cannot rename EPYC now, but before we introduce Ryzen and
> Threadripper let's thing about it and come up with better names, for
> example Zen-Client/Zen-Server Zen+-Client or something like that.
> 
> Pavel

-- 
Eduardo