Bug#412069: patch for beryl support

[Michel Dänzer <daenzer@debian.org>]

On Mon, 2007-02-26 at 13:12 +0100, Robert Millan [ackstorm] wrote:
> On Mon, Feb 26, 2007 at 12:39:45PM +0100, Xavier Bestel wrote:
> > On Mon, 2007-02-26 at 11:44 +0100, Robert Millan [ackstorm] wrote:
> > > My intel card can do without either XAANoOffscreenPixmaps or AddARGBGLXVisuals.
> > > No difference can be found on first sight (and I tested most basic stuff: cube,
> > > skydome, etc).
> > > 
> > > nVidia doesn't need AddARGBGLXVisuals, but it needs XAANoOffscreenPixmaps.

The latter is weird, as TTBOMK the nvidia driver doesn't use XAA at all.

> > > I don't know about ATI.  But ATI seems to be so badly screwed wrt Beryl that
> > > we shouldn't care much.
> > 
> > Beryl works quite well on my ATI r300 using XAANoOffscreenPixmaps -
> > well, excepted I can't resize windows and sometimes the whole thing just
> > freezes.
> 
> Yes, but as Brice said before we shouldn't enable these options unless we
> know what the drawbacks are.  Maybe you can investigate about that?

The option is only needed to work around bugs in XAA. Because basically
everything is a pixmap when windows are redirected (i.e. when a
compositing manager is running), it effectively disables most 2D
acceleration in that case and still a large portion of it without a
compositing manager. So this option can't be enabled by default, because
it hurts performance in all cases *except* when running a GLX
compositing manager.

> My point is that if we don't figure that out satisfactorily in time, we could
> just enable the Composite extension, which sounds fairly safe, and seems to be
> enough for Intel cards.  And Intel happens to be the card brand we have the
> best driver support for (compared to a RE'd driver for ATI and nothing for
> nVidia), so focusing on it makes sense to me.

Yes, that should be mostly safe at this point. The only exception that
comes to mind offhand is that fglrx disables the DRI when Composite is
enabled.


-- 
Earthling Michel Dänzer           |          http://tungstengraphics.com
Libre software enthusiast         |          Debian, X and DRI developer