AMD open-source developer Michel Dänzer removed the limitation today that limited GLAMOR to being used for just R600 and newer GPUs. GLAMOR is a means of having 2D acceleration over OpenGL in a GPU/driver agnostic manner rather than driver-specific hard-coded 2D acceleration paths. For anyone having issues with EXA or just wanting to toy around with GLAMOR, it can now be enabled for hardware going back to the R300 class by setting the AccelMethod to GLAMOR within the xorg.conf configuration file of the system. EXA is still used by default in the xf86-video-ati X.Org driver except for the Radeon HD 7000 series and newer where only GLAMOR is supported with EXA being abandoned.
The change enabling the older GLAMOR support can be found by this commit. GLAMOR may work for R500 (Radeon X1000 series) hardware but when enabling GLAMOR for older R300 GPUs there will be a Xorg.0.log warning about potentially bad 2D support. Developers are currently working on major GLAMOR performance improvements but for now the Radeon GLAMOR performance is actually quite bad.