Re: [PATCH 1/1] virtio-gpu: CONTEXT_INIT feature

[Gerd Hoffmann <kraxel@redhat.com>]

  Hi,

> > This needs a config option, simliar to the other features.  It is a
> > guest-visible change so we must be able to turn it off for live
> > migration compatibility reasons.  We also need a compat property to
> > turn it off by default for 6.1 + older machine types.
> 
> Could you give me a hint on how to add this compat property?

No need to do that for now, see below.  But "git log" or "git blame"
should find the patches doing the same for the other features).

> > > +    if (cc.context_init) {
> > > +        virgl_renderer_context_create_with_flags(cc.hdr.ctx_id,
> > > +                                                 cc.context_init,
> > > +                                                 cc.nlen,
> > > +                                                 cc.debug_name);
> > 
> > This requires a minimum virglrenderer version I guess?
> 
> Definitely, that is going to be >= 0.9.0

... because we can hardly enable that by default if it isn't even
released.  We'll need #ifdefs so qemu continues to build with older
virglrenderer versions for a while.  It also must stay disabled by
default so you don't get different qemu behavior depending on the
version compiled against.

Then, in 1-2 years, when distributions have picked up the new version,
we can consider to raise the minimal required version to 0.9.0 and flip
the default to enabled.

> > > --- a/include/standard-headers/linux/virtio_gpu.h
> > > +++ b/include/standard-headers/linux/virtio_gpu.h
> > 
> > Separate patch please.
> > Also use scripts/update-linux-headers.sh for this.
> Well, then I believe we will need to wait for this patch series:
> 
> https://www.mail-archive.com/dri-devel@lists.freedesktop.org/msg367531.html

Ah, right.  Too much stuff on my todo list :(

take care,
  Gerd