While the setup process isn't ideal, it should be improved in the coming releases. However, once the CrossFire chain is enabled, computing can go on as normal. There is no need to mess with any environmental variable (like what's needed with SLI) or any other steps in order for CrossFire to work. Instead, the driver detects the name of the OpenGL program being called, and if it's Doom 3, Quake 4, or Enemy Territory: Quake Wars, it will split the workload between the installed Radeon GPUs. If any of those id Software titles have a renamed binary, it will not be detected and therefore no CrossFire. Additionally, renaming other OpenGL programs to etqw.x86 or doom3 will not do any good. We had tried this and it simply resulted in problems.
With Catalyst 8.8 there's also a few in-game problems. These problems mostly came down to segmentation faults with Enemy Territory: Quake Wars. This problem should largely be fixed next month with Catalyst 8.9. Aside from these encounters, the CrossFire Linux experience has been reliable. At this time no information pertaining to CrossFire is displayed within the Catalyst Control Center.
Our test system for benchmarking CrossFire on Linux consisted of an Intel Core 2 Duo E8400 clocked at 4.00GHz, ASUS P5E64 WS Professional (Intel X48) motherboard, 2GB of OCZ DDR3-1333MHz memory, Western Digital 160GB Serial ATA 2.0 hard drive, and an OCZ EliteXStream 800W power supply. The graphics cards we used for testing were two Diamond Radeon HD 4850 512MB and two Sapphire Radeon HD 4870 512MB graphics cards. We will be delivering CrossFire results from a VisionTek Radeon HD 4870 X2 2GB graphics card later this week. On the Linux side of things we were using Ubuntu 8.04.1 32-bit with the Linux 2.6.24 kernel and X Server 1.4.1.
For testing we were using the Phoronix Test Suite 1.2.0 Beta 2. This version officially released this morning contains the latest developments in the Phoronix Test Suite and this includes detection support for ATI CrossFire on Linux as well as reading frequency and thermal information through ATI OverDrive. With the Phoronix Test Suite we had used the Doom 3, Quake 4, and Enemy Territory: Quake Wars test profiles, seeing as those are the only OpenGL programs supported by CrossFire on Linux at this time. In the future we will hopefully see CrossFire support for the Lightsmark and Unigine test profiles. In order to make these Linux-native tests demanding enough upon modern-day graphics processors, we had run Doom 3 at 2560 x 1600 with ultra quality, Quake 4 at 1920 x 1200 with ultra quality, Quake 4 at 2560 x 1600 with ultra quality, Enemy Territory: Quake Wars at 1680 x 1050, Enemy Territory: Quake Wars at 1920 x 1200, and Enemy Territory: Quake Wars at 2560 x 1600. We had run these tests without any antialiasing (AA) or anisotropic filtering (AF), then again with 8x AA, and finally with 8x AA and 16x AF. On the following pages are our results.