[PATCH] cpu_map: Introduce A64FX

[Jiri Denemark]

On Wed, Aug 31, 2022 at 15:11:41 +0100, Daniel P. Berrangé wrote:
> On Wed, Aug 31, 2022 at 02:30:52PM +0200, Jiri Denemark wrote:
> > On Wed, Aug 31, 2022 at 09:22:16 +0000, Liu Yiding wrote:
> > > Add A64FX as a supported cpu model.
> > > 
> > > Signed-off-by: Liu Yiding <liuyd.fnst at fujitsu.com>
> > > ---
> > >  src/cpu_map/arm_A64FX.xml   | 6 ++++++
> > >  src/cpu_map/arm_vendors.xml | 1 +
> > >  src/cpu_map/index.xml       | 3 +++
> > >  src/cpu_map/meson.build     | 1 +
> > >  4 files changed, 11 insertions(+)
> > >  create mode 100644 src/cpu_map/arm_A64FX.xml
> > 
> > CPU detection for ARM is a bit awkward and not very useful in practice.
> > It will (in some cases) report the host CPU in host capabilities, but
> > that's it. The CPU from host capabilities cannot really be used in
> > general for specifying a guest CPU in domain XML and it would not even
> > make a lot of sense as I believe the only really supported CPU for KVM
> > is "host" (mode="host-passthrough" in domain XML).
> 
> This still lets it be used for a guest with TCG, which has no requirement
> to use 'host'.

The host CPU is irrelevant for TCG and libvirt on ARM has always allowed
any CPU model to be used, even those that are not in cpu_map. And since
a lot of the ARM CPUs in cpu_map do not match anything in QEMU anyway,
which is the reason why host CPU detection on ARM is mostly a cosmetic
thing.

> > I'm not saying the patch is wrong, I'm just trying to make sure you
> > don't expect something more from implementing this patch.

Jirka