[Spice-devel] [PATCH v2 spice-protocol 2/2] Add unix GL scanout messages

[Marc-André Lureau]

Hi

----- Original Message -----
> On Fr, 2015-12-18 at 03:47 -0500, Marc-André Lureau wrote:
> > Hi
> > 
> > ----- Original Message -----
> > > > 
> > > > If you create a "primary" surface with surface_create, that's
> > > > basically all you need to start displaying. It could quite easily
> > > > learn to take a shm fd while keeping the rest of the Spice
> > > > qxl/2od/canvas semantic.
> > > 
> > > But then you still stream all the qxl commands and image data over the
> > > socket, so you don't save much compared to non-shm case.
> > 
> > I mean you could just share a QXL primary surface, display it and not draw
> > into it.
> 
> Which VGA?  Workflow is quite different on qxl and anything else.
> With qxl we'll go send the guests qxl render commands over to the
> client, and the client renders it.  On the qemu/server side there is no
> rendered primary surface, unless someone asks for it and we kick the
> local renderer on the server side to satisfy the request.  Sharing the
> primary surface doesn't buy us much here IMO.


..Yes (I know), this is all hypotetical, based on discussion from Frediano to extend scanout to shm/canvas. fwiw, the server does all the rendering at some point or another, so imho, it would be still a good idea to simply share the server surface...
 
> With stdvga/cirrus/virtio-vga(in-2d-mode) the guest renders into a
> framebuffer.  qemu creates a primary surface and sends over updates
> (simple image blits), using dirty page tracking on the guest frame
> buffer, pretty much like vnc.  *Those* updates can easily be dropped by
> placing the primary surface into shared memory instead.  And it would be
> very simliar to the opengl mode, qemu would copy from guest memory to
> shared memory then instead of copying from guest memory to (dma-buf
> exported) opengl texture.

again, that's for the people who don't know how this stuff work, I have a fair bit of experience with all that. But thanks anyway ;)