Re: [Qemu-devel] [PATCH v2 4/6] qmp: Add runnability information to query-cpu-definitions

[Eduardo Habkost]

On Wed, Jun 22, 2016 at 11:00:47AM +0200, Markus Armbruster wrote:
> Eduardo Habkost <address@hidden> writes:
> 
> > 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 <address@hidden>
> > Cc: Michael Mueller <address@hidden>
> > Cc: Christian Borntraeger <address@hidden>
> > Cc: Cornelia Huck <address@hidden>
> > Cc: Jiri Denemark <address@hidden>
> > Cc: address@hidden
> > Signed-off-by: Eduardo Habkost <address@hidden>
> > ---
> > Changes v1 -> v2:
> > * Remove @runnable field, non-empty @unavailable-features is
> >   enough to report CPU model as not runnable.
> > * Documentation updates:
> >   * Changed to "(since 2.7)";
> >   * Add more details about the exact meaning of
> >     unavailable-features, and what it would mean to see
> >     read-only QOM properties in the list, and that
> >     implementations can return "type" if there's
> >     no extra information available;
> > ---
> >  qapi-schema.json | 23 ++++++++++++++++++++++-
> >  1 file changed, 22 insertions(+), 1 deletion(-)
> >
> > diff --git a/qapi-schema.json b/qapi-schema.json
> > index 8483bdf..43478e9 100644
> > --- a/qapi-schema.json
> > +++ b/qapi-schema.json
> > @@ -3005,11 +3005,32 @@
> >  # Virtual CPU definition.
> >  #
> >  # @name: the name of the CPU definition
> > +# @unavailable-features: #optional List of properties that prevent
> > +#                        the CPU model from running in the current
> > +#                        host. (since 2.7)
> > +#
> > +# @unavailable-features is 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 there's no known
> > +# way to make the CPU model run in the current host. If
> > +# absolutely no extra information will be returned to explain why
> 
> Suggest "can be returned".

I believe that "extra information can be returned" will always be
true (we just need an appropriate property name to represent that
information). But people writing architecture-specific code are
free to decide if the extra effort is worth it, or if "type" is
good enough for them.

> 
> > +# the CPU model is not runnable, implementations may simply
> > +# return "type" as the property name.
> > +# 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.
> > +# If @unavailable-features is an empty list, the CPU model is
> > +# runnable using the current host and machine-type.
> > +# If @unavailable-features is not present, runnability
> > +# information for the CPU is not available.
> >  #
> >  # Since: 1.2.0
> >  ##
> >  { 'struct': 'CpuDefinitionInfo',
> > -  'data': { 'name': 'str' } }
> > +  'data': { 'name': 'str',
> > +            '*unavailable-features': [ 'str' ] } }
> >  
> >  ##
> >  # @query-cpu-definitions:
> 
> With the commit message tidied up as per your reply to Jiri:
> Reviewed-by: Markus Armbruster <address@hidden>

Thanks!

-- 
Eduardo