As some more good news today besides AMD's press oddly talking up their open-source Linux driver is work done by Marek Olšák, the open-source developer that started contributing great amounts of code to the AMD driver as a student and is now employed by the company, for implementing the GL_ARB_buffer_storage extension.
The ARB_buffer_storage extension was one of the big additions to the OpenGL 4.4 core specification. This OpenGL buffer storage extension allows more fine-grained control for developers to request where memory buffer objects are stored when it comes to dealing with APUs/SoCs and other systems with separated discrete video memory, system memory, etc. Having more control over the memory buffer placement and its cache handling can lead to greater performance by games and applications. More details on the ARB_buffer_storage OpenGL extension from the Khronos Group can be found via the official OpenGL.org registry specification.
Marek has implemented this OpenGL extension for all of AMD's Radeon Gallium3D graphics drivers and comes just a day after he posted a big AMD Radeon memory patch-set that can allow for significant performance improvements for systems with limited amounts of video RAM.
The ARB_buffer_storage Radeon hook-up happened with this Git commit after making the necessary changes.