Re: [RFC 21/21] arm/cpu-features: Document custom vcpu model

[Kashyap Chamarthy <kchamart@redhat.com>]

On Mon, Oct 28, 2024 at 05:29:11PM +0100, Cornelia Huck wrote:
> On Mon, Oct 28 2024, Daniel P. Berrangé <berrange@redhat.com> wrote:

[...]

> >> We could consolidate that to the current "host" model, once we figure
> >> out how to handle the currently already existing properties. Models
> >> based on the different architecture extensions would probably be more
> >> useable in the long run; maybe "custom" has a place for testing.
> >
> > If you can set the features against "host", then any testing could
> > be done with "host" surely, making 'custom' pointless ?
> 
> We might differentiate between "do some consistency checks" and "allow
> a completely weird wolpertinger"; if we agree that we don't need it,
> then we surely could drop it again.

Yeah, FWIW, I agree that it's best to drop "custom" if all the
meaningful tests can be handled by being able to add/remove CPU flags
from `-cpu host`.


Related: I don't see any mention of `-cpu max` here.  Is it not
relevant?  It is currently defined as: "enables all features supported
by the accelerator in the current host".  Does it make sense for `max`
to allow disabling features?  Or is the idea that, why would you choose
`-cpu max` if you want to disable features?  In that case, go with
either:

    -cpu host,feat1=off

Or:

    -cpu some_future_named_model,$feat1=off

?

-- 
/kashyap