[libvirt] [PATCH 7/9] qmp: Add runnability information to query-cpu-definitions
Eduardo Habkost
ehabkost at redhat.com
Mon May 9 12:36:30 UTC 2016
On Mon, May 09, 2016 at 02:05:05PM +0200, David Hildenbrand wrote:
> > On Mon, May 09, 2016 at 10:54:53AM +0200, David Hildenbrand wrote:
> > > > Extend query-cpu-definitions schema to allow it to return two new
> > > > optional fields: "runnable" and "unavailable-features".
> > > > "runnable" will tell if the CPU model can be run in the current
> > > > host. "unavailable-features" will contain a list of CPU
> > > > properties that are preventing the CPU model from running in the
> > > > current host.
> > > >
> > > > Cc: David Hildenbrand <dahi at linux.vnet.ibm.com>
> > > > Cc: Michael Mueller <mimu at linux.vnet.ibm.com>
> > > > Cc: Christian Borntraeger <borntraeger at de.ibm.com>
> > > > Cc: Cornelia Huck <cornelia.huck at de.ibm.com>
> > > > Cc: Jiri Denemark <jdenemar at redhat.com>
> > > > Cc: libvir-list at redhat.com
> > > > Signed-off-by: Eduardo Habkost <ehabkost at redhat.com>
> > > > ---
> > > > qapi-schema.json | 10 +++++++++-
> > > > 1 file changed, 9 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/qapi-schema.json b/qapi-schema.json
> > > > index 54634c4..450e6e7 100644
> > > > --- a/qapi-schema.json
> > > > +++ b/qapi-schema.json
> > > > @@ -2948,11 +2948,19 @@
> > > > # Virtual CPU definition.
> > > > #
> > > > # @name: the name of the CPU definition
> > > > +# @runnable: true if the CPU model is runnable using the current
> > > > +# machine and accelerator. Optional. Since 2.6.
> > > > +# @unavailable-features: List of properties that prevent the CPU
> > > > +# model from running in the current host,
> > > > +# if @runnable is false. Optional.
> > > > +# Since 2.6.
> > >
> > > Just FYI, on other architectures (e.g. s390x), other conditions (e.g. cpu
> > > generation) also define if a CPU model is runnable, so the pure availability of
> > > features does not mean that a cpu model is runnable.
> > >
> > > We could have runnable=false and unavailable-features being an empty list.
> >
> > Even on those cases, can't the root cause be mapped to a QOM
> > property name (e.g. "cpu-generation"), even if it's property that
> > can't be changed by the user?
>
> In the current state, no.
But it could be implemented by s390x in the future, if it's
considered useful, right?
>
> So I think for runnable=false:
> a) unavailable-features set -> can be made runnable
> b) unavailable-features not set -> cannot be made runnable
>
> would be enough.
I understand it would be enough, but I would like to at least
define semantics that would make sense for all architectures in
case it gets implemented in the future. Would the proposal below
make sense?
> >
> > We could replace this with something more generic, like:
> >
> > @runnability-blockers: List of attributes that prevent the CPU
> > model from running in the current host.
> >
> > A list of QOM property names that represent CPU model
> > attributes that prevent the CPU from running. If the QOM
> > property is read-only, that means the CPU model can never run
> > in the current host. If the property is read-write, it means
> > that it MAY be possible to run the CPU model in the current
> > host if that property is changed.
> >
> > Management software can use it as hints to suggest or choose an
> > alternative for the user, or just to generate meaningful error
> > messages explaining why the CPU model can't be used.
> >
> > (I am looking for a better name than "runnability-blockers").
> >
>
>
>
> David
>
--
Eduardo
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