Re: [PATCH 1/6] accel: Introduce 'query-accels' QMP command

[Andrew Jones]

On Fri, Mar 12, 2021 at 09:11:45AM +0100, Thomas Huth wrote:
> On 12/03/2021 08.42, Marc-André Lureau wrote:
> > 
> > 
> > On Fri, Mar 12, 2021 at 3:14 AM Philippe Mathieu-Daudé
> > <philmd@redhat.com <mailto:philmd@redhat.com>> wrote:
> > 
> [...]
> >     +##
> >     +# @AcceleratorInfo:
> >     +#
> >     +# Accelerator information.
> >     +#
> >     +# @name: The accelerator name.
> >     +#
> >     +# Since: 6.0
> >     +##
> >     +{ 'union': 'AcceleratorInfo',
> >     +  'base': {'name': 'Accelerator'},
> >     +  'discriminator': 'name',
> >     +  'data': { } }
> > 
> >     +
> > 
> > 
> > Making room for future details, why not.
> 
> I think we definitely need the additional data section here: For KVM on
> POWER, it would be good to know whether it's KVM-HV or KVM-PR, for KVM on
> MIPS it would be good to know whether it's KVM_VM_MIPS_VZ or KVM_VM_MIPS_TE,
> for KVM on x86 whether it's the AMD flavor or Intel, ...

Could also pre-expand all of these and list them individually.

> 
> >     +##
> >     +# @query-accels:
> >     +#
> >     +# Get a list of AcceleratorInfo for all built-in accelerators.
> >     +#
> >     +# Returns: a list of @AcceleratorInfo describing each accelerator.
> >     +#
> >     +# Since: 6.0
> >     +#
> >     +# Example:
> >     +#
> >     +# -> { "execute": "query-accels" }
> >     +# <- { "return": [
> >     +#        {
> >     +#            "type": "qtest"
> >     +#        },
> >     +#        {
> >     +#            "type": "kvm"
> >     +#        }
> >     +#    ] }
> >     +#
> >     +##
> >     +{ 'command': 'query-accels',
> >     +  'returns': ['AcceleratorInfo'] }
> > 
> > 
> > That's nice, but how do you know which accels are actually enabled?
> 
> I guess we need two commands in the end, one for querying which accelerators
> are available, and one for querying the data from the currently active
> accelerator...?
>

If we listed each accelerator individually, then we could use booleans
for them, where only the active one would be true. If we can't come up
with another need for the accelerator-specific info now, then I'd leave
it to be added at a later time when it is needed.

Thanks,
drew