DRI on dual-head: what's needed?

[Nemosoft Unv.]

Hello,

On Friday 11 May 2007 06:38, Leoncio Juan Ernesto López (Cholo) wrote:
> On 5/10/07, Nemosoft Unv. <nemosoft at smcc.demon.nl> wrote:
> > Hello,
> >
> > I've got myself a dual-head setup here with a card based on a Radeon 9200
> > SE, XOrg 7.2 (the release, not the latest code), which works fine.
> > However, when starting up X, I get this message in the log:
>
> What kind of dual-head config "variety" are you using? Xinerama?

No, nothing of the kind. No Xinerama, no MergedFB: just two indepedant 
displays. This is the key section from xorg.conf:

Section "ServerLayout"
        Identifier      "Dual"
        Screen          0 "small" RightOf "large"
        Screen          1 "large" 0 0

> Forgive my ignorance, but I think MergedFB is the only way to have DRI
> working in both heads.

Well, I would also be happy to have DRI working on one (configurable) display. 
But first I would like to know why it's simply disabled at all. 

> > But, I specifically DON'T want MergedFB since I want a dual display (i.e.
> > a :0.0 and :0.1 X display). I looked at the code, and there's no specifi
> > reason listed why it doesn't work. So my question to you is: what is
> > needed to get this working? Or rather, where is the problem? Is it the
> > DRI kernel module, the X architecture, hardware issue?
>
> Is it *reeealy* necessary to have both displays? (not criticizing, just
> curious)

Yes. First, the screens differ in resolution, so a buffer like MergedFB has a 
large space that will not be used; it also tends to confuse programs. Second, 
and that is the main reason: because the displays are independant, I can have 
one display set up with mail, a webcam, IRC, or Google searches while on the 
other I can program, debug, watch TV and basicly switch desktops any way I 
like, while the other screen remains stationary. This is simply impossible 
with MergedFB.

 - Nemosoft