Radeon X300, dual head

Kenvor Cothey kenvor at heaven.li
Mon Jul 13 18:25:10 PDT 2009

 > On Fri, Nov 21, 2008 at 5:50 PM, Hans J. Koch <hjk at linutronix.de 
<http://lists.freedesktop.org/mailman/listinfo/xorg>> wrote:
 > > Hi,

> > I used to have a working system with a Radeon X300 (RV370) card and two
> > monitors 1680x1050 each. I used an ancient xorg version (something like
> > 6.8, can't recall) and had a MergedFB+Xinerama configuration. Worked well
> > for me.
> >
> > A few days ago I dist-upgraded my Debian sid which brought me version
> > 7.3 of xserver-xorg. Since that I'm trying to get my dual head setup
> > working again...
> >
> > I understand that MergedFB has been replaced by RandR 1.2 extensions.
> > Sounds like a good concept to me, but unfortunately it doesn't work here.
> >
> > X correctly detects my hardware, but no matter what I do, I always have
> > the same output on DVI-0 and VGA-0. I googled around and found a lot of
> > pages describing how to setup xorg.conf, and I think it's OK.
> >
> > Question: Is this supposed to work or a known problem? What do I have
> > to do to get a working dual head setup again?
> yes it should work.  you may need to add a virtual line to your config
> to reserve enough framebuffer space for your config.  This page gives
> a pretty good overview of how to configure things with xrandr:
> http://wiki.debian.org/XStrikeForce/HowToRandR12
> One problem that comes up from time to time is that the xserver will
> clone the outputs (drive both monitors with the same display
> controller rather than with independent display controllers).  The
> xrandr utility doesn't seem to be smart enough to grab a new crtc when
> you select multi-head, so you sometimes have to specify the crtc.  run
> xrandr --verbose to see how the topology is configured.
> You can use this set of commands to specify a crtc:
> xrandr --output VGA-0 --off
> xrandr --output VGA-0 --crtc1 --mode 1680x1050
> xrandr --output VGA-0 --right-of DVI-0
> Alex

Hi -

I've recently upgraded my desktop distribution from Fedora 10 to Fedora 
11, having worked up from various prior versions of Fedora. I too have 
an X300, which was working magnificently in dual head mode, originally 
in F9, and then, with a minor hack (I had to downgrade the radeon driver 
to the F9 version, 6.8.0-12) in F10. Now I'm at F11, it seems I can no 
longer make dual head work (the downgrade hack doesn't work, presumably 
due to incompatible versions). Having googled around, the description 
above is the best, most recent, fit I can find for the symptoms I'm 

However, the solution that Alex suggests is not solving the problem; I 
am still stuck with both monitors displaying either the left hand side 
or the right hand side of the desktop (which exists, virtually - I can 
drag and drop windows off the side of the display and subsequently 
switch the monitors' - collective - view to see them). Worse, xrandr 
--verbose reports DVI-0 and VGA-0 on different CRTCs. Could the x server 
be cloning upstream of the video hardware?

I am on version of the Xorg server, and 6.12.2 of the radeon 
driver. Any suggestions much appreciated. I'm happy to post appropriate 
logs/dumps/etc if these will be of help (mostly greek to me).


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