I can speak about Eyefinity on Linux. With the open drivers in 11.10 Ubuntu, I actually have all three displays working properly (with the Cayman 69xx), and I can rearrange them as I like with the Ubuntu display manager without rebooting each time with Unity 3d. However, the fan/power management with the OSS drivers sucks (really noisy), and there's no OpenGL 3.2+ support.
With the FGLRX drivers, I have quite the headache getting them working. First off, there's no support for Unity 3d with Eyefinity and catalyst. I have to use Unity2d or it will be a wonky experience (or just knock me back to log-in screen). If I disable compositing engine, and turn on the tear-free option, then I don't get any tearing like most other people claim to.
As for setting up Eyefinity with the CCC, it is a royal pain. Using either 11.8 from the repos, or 11.9 from AMD, CCC almost always crashes when I make a monitor change if I don't load it from the terminal with "sudo amdcccle" - WTF? If I launch it from the terminal, then it usually doesn't crash, but moving monitors around in the display config manager is a weird thing. Do not attempt to rearrange them as you would like to, as it will screw something up in your Xorg.conf. Here's how I can manipulate them: click on the down arrow on a monitor, and go to multi-display with multi-monitor with monitors: X & X(something like that), and just click it. When you do that, it will probably rearrange the ordering of the monitors it shows. Just click that over and over changing which monitor you do it from, until eventually you have it configured the way you want. -Geez.
And for some reason, when I try and make a XBMC go full screen, it doesn't use the eyefinity resolution, and instead just changes my config to clone across three screens. But I can just use the windowed version and drag it across multiple monitors (that sucks). Also, no options for bezel correction like in Windows.
Hi, XBMC dont have support for multi display, you can try XVBA API to get the eyefinity support. And as far as i know bezel is not supported for Linux, it is only designed for Windows OS.