So I've been using ubuntu with multi-monitor with mixed results since 6.06, but for over a year now i've had a rig with a 5870 eyefinity6 card driving 6x 1920x1200 displays, and have made it *mostly* usable, with dual screen compositing, compiz, and most eyecandy for the desktop. The worst part has been since 11.04 it's steadily gotten worse and worse because of both gtk3 and unity as all the *features* gtk2 figured out along the way were somehow forgotten it seems. Biggest issue is the 5870 can only do 8192 wide res, so I have to split it into a 3 monitor by 2 framebuffer design, and literally nothing seems to ever assume this config in software. Even nautilus causes weird graphical anomalies now.
My woes mostly surround what seems to be the driver slowly degrading over time. My system seems to show sign of a memory leak, but the fglrx module seems to continue growing in size until screens start flickering, and eventually my glmatrix screensaver causes it to simply hard-lock, requiring manual reset. Anything gl-based, especially compiz, awn/cairo-docks, chrome even with compositing enabled is suspect, and anything that uses it like minecraft can seriously piss it off when it's getting sketchy already.
I've done most things like disabling vsync that helps tremendously (in everything manually, which sucks), set manual 5760x1200 displays in compiz, and tried adjusting things up and down to see what helps and what doesn't. It will always eventually die hard after degrading visually with flickering usually telling me when to expect a reboot.
I'd love to think I'm not the only one crazy enough to do this, and i'd love to know what others' mileages are with something like this. I figured here is probably the best place since I'm putting money that it's either the amd driver (this behavior gets better/worse between driver revisions), and probably gl-based direct-rendering software doing something it shouldn't between. Any advice where to start debugging something like this? Logs have nothing I've found that indicate graphics problems, and ultimately need to find out how to debug fglrx and why it death-spirals eventually with compiz.
I doubt that you can debug fglrx much. 6 monitors are not the normal use case, nvidia is now up to 4 with one card. Maybe they have got a similar 8192x8192 limit. Did you ever try using the oss drivers? If you only play minecraft that should not be so critical. Also you could try kde. Maybe show us a picture of your desktop, must look really cool. I have got more pcs than displays, i can not test it anyway
Well, that's more or less the way I've always looked at it, that the proprietary drivers probably won't include debugging symbols or anything to be effective. Not sure it's enough to put debug packages of xorg in without that. I love proprietary blobs!
I did try the oss drivers at one point out of box with 11.10 on a fresh install, though I couldn't get any compositing to occur, not enough for compiz or any gl-based game. Plus without xinerama, all I got was 1x6 framebuffers that are useless by themselves isolated with most apps being too stupid to run in multiple display exports. This would solve a lot of issues if applications would have a general method of launching into separate processes or render between multiple displays.
I have a picture somewhere of it, though I should probably clean it up a bit and take a nice rockstar pic of it too.