Dual screen on ATI 9600 | NV350 AQ using radeon driver - clone only ?

[Alex Deucher]

On 3/16/09, Torbjørn Thorsen - Nextline <torbjorn at nextline.no> wrote:
> I have to identical monitors running at 1280x1024.
>
>  torbjorn at torbjorn-desktop:~$ xrandr | grep connected
>  VGA-0 connected 1280x1024+0+0 (normal left inverted right x axis y axis)
>  338mm x 270mm
>  DVI-0 connected 1280x1024+0+0 (normal left inverted right x axis y axis)
>  338mm x 270mm
>  S-video disconnected (normal left inverted right x axis y axis)
>
>  The first problem was the Virtual size was too small to fit two of both
>  outputs, so that got configured in xorg.conf.
>
>  Screen 0: minimum 320 x 200, current 1280 x 1024, maximum 2560 x 1024
>
>  So now I should be ready for running dual screen ?
>
>  torbjorn at torbjorn-desktop:~$ xrandr --dryrun --output DVI-0 --right-of VGA-0
>  screen 0: 2560x1024 675x270 mm  96.33dpi
>  crtc 0:    1280x1024   60.0 +1280+0 "DVI-0" "VGA-0"
>
>  The result of doing this is that both outputs end up with the same
>  offset, in effect, I can only see the right side of the virtual screen.
>
>  torbjorn at torbjorn-desktop:~$ xrandr | grep connected
>  VGA-0 connected 1280x1024+1280+0 (normal left inverted right x axis y
>  axis) 338mm x 270mm
>  DVI-0 connected 1280x1024+1280+0 (normal left inverted right x axis y
>  axis) 338mm x 270mm
>
>  I have tried lots of different ways to get them to show the whole
>  virtual screen, including using --pos, but I can't get them to split.
>  The outputs always see the same area of the virtual screen.
>
>  If anybody could point me in the right direction, I would be very grateful.

Both outputs are probably ending up on the same crtc by default (use
xrandr --verbose to verify).  So you probably want something like:
xrandr --output DVI-0 --crtc 1 --mode 1280x1024 --right-of VGA-0

This page has a lot of good information about configuration using xrandr:
http://wiki.debian.org/XStrikeForce/HowToRandR12

Alex