One of the first things I tried when I got my new PC was to load Ubuntu up on it. The install went fine, but the video driver (ATI Radeon X800 GT, dual head DVI out) wasn’t supported out of the box (or off the CD in this case). I downloaded the Ubuntu 6.10 beta the other day (I couldn’t wait for it to come out properly) and installed that to find the same thing – it installed fine but I was left in text mode.
I did get things working nicely (dual screens, 85Hz refresh rates) by doing the following. This may work in Ubuntu 5.10 or 6.06, I don’t know.
1. sudo apt-get install xserver-xorg-video-ati
2. Edited the file /etc/X11/xorg.conf and changed Driver “ati” to Driver “radeon”
3. Restarted GDM (/etc/init.d/gdm restart)
Much to my surprise, Gnome cranked up. I couldn’t believe it was that easy. My next task was to get dual screens working. This took me about 30 mins to Google around and find the various answers to.
Now, it would appear that the main fear that strikes xorg.conf hackers is that their changes to config files will render their Xwindows system inoperable. I saw one post by some guy who said that after adding a directive to his xorg.conf file he had to reinstall Linux. I can only imagine that he didn’t take a backup of the file and when he tried to undo his changes he undid them in the wrong place. The solution to this of course is to back up your xorg.conf file, i.e. cp /etc/X11/xorg.conf /etc/X11/xorg.conf.bak.
The first useful tip I came across was this tip from henriquemaia:
… instead of restarting gdm, one should first test if the configuration is right. As most newbies wouldn’t know what to do if their X is lost, it’s better to dosudo xinit -- :2
where one can see the result on a new X (ctrl+alt+F9) without losing the first. If something goes wrong, one can easily use the backup configuration under their surviving X (ctrl+alt+F7).
Once you issue that command (from an xterm) you might get a blank hashed background. This is a test to show you that your xorg.conf settings are correct. Once happy that it looks ok, press Ctrl-Alt-Backspace to kill that session.
I then found this article by Peter Van den Wildenbergh that discussed how to set up three screens on a SUSE linux box. Same applied for me, except I only had two screens. Read it carefully, and pay attention to the relationship between a screen, a monitor and a device. A screen is a virtual device which combines a monitor (a physical monitor with various capabilities) and a device (which is your graphics card which will probably be on some BusID like BusID “1:0:0″.
To get the refresh rate of 85Hz I went to this Modeline Tool page where I selected my desired resolution and frequency and it responded with the correct Modeline to insert into my xorg.conf file in each of the Monitor sections.
Before you ask, I don’t know if 3D gfx are supported with this setup, or anything else but what I do know is that I have a dual monitor layout with a good resolution and good refresh rate and a nice open source feel-good vibe
Here is my xorf.conf file with the above settings: xorg.conf