I have installed Ubuntu 10.04 after a major crach with 9.10 on a machine with 3x 5970 in it. I have the monitor hooked up to the first card, I got 10.4 driver installed which worked fine with Ubuntu 9.10. (10.6 is said to be buggy with OpenCL, so I went back to this last working one)
I got the driver installed correctly, it gives back 6 devices, however when I run aticonfig --adapter=all --initial -f then it makes a xorg.conf file which renders Ubuntu unable to boot. I checked the config file and it seems awfully long. I don`t remember it being so long under Ubuntu 9.10.
Could someone post a proper multi-gpu xorg.conf that is working under 9.10? Or 10.04 would be best if someone could get all devices recognized by OpenCL.
I have tried with driver 10.6, but that either crashed with memory trash on the screen while trying to startx on boot, or it started up fine after the magic aticonfig command (don`t ask me why it works once and not the second time) but it still could not get the cards recognized by CAL FindNumDevices (even with export DISPLAY=:0).
Anyone with ideas or a proper xorg.conf file?
The multi-gpu support on Ubuntu 10.04 is broken since the release of Catalyst 10.5, you can find the details here: http://ati.cchtml.com/show_bug.cgi?id=1828
You have to delete the /dev/vga_arbiter before to start X11 or the Xserver will crash. This fix the problem on my Ubuntu 10.04 + Catalyst 10.6 + 5870 + 5850 installation.
However it looks like 5970 has its own set of problems so I don't know if the above workaround will fix all your problems.