Re: [Qemu-devel] [PATCH v6 05/11] vhost-user: add vhost_user_gpu_set_socket()

[Gerd Hoffmann]

  Hi,

> > > +Wire format
> > > +===========
> > > +
> > > +Unless specified differently, numbers are in the machine native byte
> > > +order.
> > > +
> > > +A vhost-user-gpu request consists of 2 header fields and a payload.
> > > +
> > > ++---------+------+---------+
> > > +| request | size | payload |
> > > ++---------+------+---------+
> > > +
> > > +Header
> > > +------
> > > +
> > > +:request: ``u32``, type of the request
> > > +
> > > +:size: ``u32``, size of the payload
> > > +
> > > +A reply consists only of a payload, whose content depends on the request.
> >
> > I'd suggest to use the same format for replies, only with "request"
> > meaning "status" in replies.  Allows for OK/ERROR status in replies,
> > and having a size field in replies too should make things more robust.
> > Also allows for an empty reply (status=ok,size=0).
> 
> 
> That brings more questions and ambiguity imho.

What questions for example?

> Can we leave that for future protocol extensions negotiated with
> GET/SET_PROTOCOL_FEATURES ?

I don't think negotiating such a basic protocol change is a good idea.

cheers,
  Gerd