Beginning next month with the Catalyst 9.4 release, support for the R300/400/500 generations of graphics processors will be dropped from AMD's mainline ATI driver. In a move they hope will allow them to focus their efforts on newer and upcoming graphics processors, the mainline Catalyst driver on both Linux and Windows will stop supporting cards older than the Radeon HD 2000 series. Linux customers affected will be encouraged to use their open-source driver stack (xf86-video-ati or xf86-video-radeonhd and Mesa) or stay with the Catalyst 9.3 driver.
Catalyst 9.3 is due out later this month and it will be the last unified release that supports the all Radeon GPUs going back to the R300 series. After that point, only the Catalyst driver that is updated monthly will only support the R600/700 series (and future ASICs). This move is beneficial to AMD by having their Catalyst developers focus primarily on their newer products and by stripping out the support for older cards so there is less code to maintain and hopefully better quality code as a result. Ideally we will see speedier and more reliable adoption of graphics processors to be released in the future. To the customer, this is a good move, permitting you are an owner of a Radeon HD 2000 graphics card or later (or an RS690/RS740 IGP, but the RS780 will remain supported). With developers being able to just focus on the newer hardware, you should see new features faster and greater reliability. If you are bound to R500 hardware or older, well, you have vintage hardware and hopefully the current Catalyst driver is good enough or you can use ATI's open-source stack. This move is similar to what happened to the R200 series support back with the fglrx 8.28.8 driver, but at that time the hardware was three generations old and the R600 series was nearing its introduction.
NVIDIA has been using a similar approach where their once very unified driver architecture now spans three legacy drivers. NVIDIA's three legacy Linux drivers plus their main Linux driver are all updated regularly with fixes and support for newer kernel / X Server releases, while new features are generally bound to their newest driver that supports the GeForce 6 series and later. AMD will be moving the R300/400/500 support to just a single legacy driver, but this branch will not be maintained. In fact, do not really look for legacy driver updates after April, as AMD does not intend to add support for newer kernel / X.Org server releases to this driver. What NVIDIA doesn't have though, is any real open-source strategy. NVIDIA's only open-source driver is xf86-video-nv, which is widely known as being obfuscated and only contains basic 2D acceleration support.
Will this move generate greater benefits within the open-source ATI stack? It does not appear AMD will be ramping up on their open-source efforts. In fact, just this week the RadeonHD driver took a serious blow as one of the three Novell developers that were responsible for its development was laid off. The remaining developers are also facing shorter work hours. When it comes to documentation, AMD has now released specifications that cover up through the latest RV770 GPUs, including what is needed for OpenGL acceleration. AMD also released DRM code for the R600/700 series that is needed as the first step in open-source 3D acceleration. At this time, the only benefits for the end-user is the ability to render a basic triangle, 2D EXA acceleration, and basic X-Video support. There is not yet any usable Mesa support for the R600/700 series, which will provide basic OpenGL support, while full-blown OpenGL support will likely not arrive until the Gallium3D infrastructure is in place. This though should all stabilize within the few years before AMD would likely drop R600/700 support from its Catalyst software.