AMD's MultiView On Linux
Introduced in the Catalyst 8.8 Linux driver and further stabilized within Catalyst 8.9 was AMD's MultiView technology. MultiView makes it possible to use multiple GPUs on the same system not for Linux CrossFire but for driving multiple display heads. Using MultiView on Linux you can easily drive four, six, or even eight screens. In fact, up to 32 displays are theoretically supported on a single system (permitting you have enough graphics cards and PCI Express slots). MultiView also allows for OpenGL acceleration across all displays and does not rely upon Xinerama. In this article we are taking a brief look at this multi-GPU multi-monitor feature catered towards AMD's workstation customers.
As described by AMD, MultiView provides "the ability to utilize GPUs from multiple adapters on an independent multi-display desktop. It allows a user to configure, manage and use a MultiView configuration under Linux and allows OpenGL applications run on any displays driven by multiple GPUs." Right now though there are several caveats when it comes to the support. MultiView will only work on systems that contain two identical FireGL graphics cards that belong to the FireGL V3300, V3350, V3400, V3600, V3700, V5200, V5600, V7400, or V7700 series. With that said, no Radeon graphics cards are currently supported by MultiView. Additionally, MultiView is not compatible with Compiz and it will not work if you are using Xinerama with X.Org. Last but not least, the RandR 1.2 support that was added in Catalyst 8.9 is disabled when using multiple ATI graphics cards.
MultiView can be controlled entirely through AMD's Catalyst Control Center Linux Edition (AMDCCCLE) application. In fact, the interface for it isn't that bad at all and is extremely easy to setup. Even if you are adjusting the layout of the monitors, AMDCCCLE has it all handled and is just as easy (if not easier) to setup compared to TwinView and Xinerama with NVIDIA's control panel.
For our testing we had just setup a simple 4-monitor configuration. You can easily setup more than that but this was a good start. Last month we shared a video of an eight-monitor MultiView setup with full OpenGL acceleration running the open-source FlightGear program. With two graphics cards being needed for our four monitor setup but only having one ATI FireGL V8600, we were left to improvise. When studying AMD's Persistent Configuration Store Data-Base (AMDPCSDB), we discovered a way to exploit the MultiView feature so that it is compatible with the Radeon graphics cards.