I was pleasantly surprised to see that the fight to get dual screens working properly with the ATI graphics card wasn’t as difficult as it has been in the past. The restricted hardware manager didn’t lock up on me after activating the ATI driver, but I still couldn’t get big desktop to work.
When trying to set up big desktop through aticonfig in the terminal I got Error: Options, e.g. --dtop and --desktop-setup, are not supported when RandR 1.2 is enabled
. I had no idea what that meant but I did a quick google search and found that someone had reported a bug with the same problem. Another person posted something that fixed it for me.
sudo killall gdm.
sudo nano (or gedit, whichever you prefer) /etc/ati/amdpcsdb to edit the file.
[AMDPCSROOT/SYSTEM/DDX]
section and add EnableRandR12=Sfalse
.sudo nano (or gedit) /etc/X11/xorg.conf, to open the xorg.conf file.
Option "EnableRandR12" "false" and Option "DesktopSetup" "horizontal".
xorg.conf file:
Section “ServerLayout”
Identifier “aticonfig Layout”
Screen 0 “Default Screen” 0 0
EndSectionSection “Files”
EndSectionSection “Module”
Load “glx”
EndSectionSection “Monitor”
Identifier “Configured Monitor”
EndSectionSection “Device”
Identifier “Configured Video Device”
Driver “fglrx”
Option “EnableRandR12″ “false”
Option “DesktopSetup” “horizontal”
BusID “PCI:1:0:0″
EndSectionSection “Screen”
Identifier “Default Screen”
Device “Configured Video Device”
Monitor “Configured Monitor”
DefaultDepth 24
EndSection