Re: Re: More virtio users

[Rusty Russell <rusty@rustcorp.com.au>]

On Mon, 2007-06-11 at 10:16 +0200, Gerd Hoffmann wrote:
> Hi,
> 
> > Framebuffer is an interesting one.  Virtio doesn't assume shared memory,
> > so naively the fb you would just send outbufs describing changed memory.
> > This would work, but describing rectangles is better.  A helper might be
> > the right approach here
> 
> Rectangles work just fine for a framebuffer console.  They stop working 
> once you plan to run any graphical stuff such as an X-Server on top of 
> the framebuffer.  Only way to get notified about changes is page faults, 
> i.e. 4k granularity on the linear framebuffer memory.

Yes, I discussed this with Ben Herrenschmidt a couple of months ago.  It
would be better to provide a fb ioctl which X could use to describe
changed rectangles if available.  In the virtio case we could hand that
information through, and other virtualized framebuffers would be able to
use it similarly.

Cheers,
Rusty.