[Spice-devel] [RFC PATCH v2 00/20] Monitor ID rework

[Gerd Hoffmann]

On Fri, Aug 24, 2018 at 09:16:09AM -0400, Frediano Ziglio wrote:
> > 
> > On Fri, Aug 24, 2018 at 11:12:43AM +0200, Lukáš Hrázký wrote:
> > > > Yes, we want this for sure.  One channel per display.
> > > 
> > > For sure? This deserves a justification.
> > 
> > That is the way modern display architectures (including wayland) are
> > working.  One framebuffer per display.  Not one huge framebuffer
> > covering all heads, then defining rectangles for each display, like qxl
> > handles multihead on linux (with xorg).
> > 
> > And the qxl way of doing multihead on linux starts to cause problems:
> > https://bugzilla.redhat.com/show_bug.cgi?id=1611141
> > 
> 
> Having a single frame buffer for channel is a current implementation
> limit which can be relaxed.

But I don't think this is possible without changing spice protocol and
qxl device.  Which opens the question whenever this is worth the trouble
or whenever we should just use virtio-gpu instead.

> I agree the main problem of this rework should be vdagent "mapping"
> of the display_id received although honestly as we are changing the
> protocol for different reasons I would remove the ugly formula and
> all its subtle assumptions all the way around.

If we absolutely have to touch the mouse messages anyway, then yes, lets
make this explicit.  But having two mouse message versions comes with
costs in terms of maintainance and backward compatibility, so I'd try to
stick to the existing message.

cheers,
  Gerd