All classic OpenGL drivers have been removed from the Mesa codebase and support for the infrastructure for their operation has been discontinued. Maintenance of the old driver code will continue in a separate βAmberβ branch, but these drivers will no longer be included in the main part of Mesa. The classic xlib library has also been removed, and it is recommended to use the gallium-xlib variant instead.
The change affects all drivers remaining in Mesa that did not use the Gallium3D interface, including i915 and i965 drivers for Intel GPUs, r100 and r200 for AMD GPUs, and Nouveau drivers for NVIDIA GPUs. Instead of these drivers, it is recommended to use drivers based on the Gallium3D architecture, such as Iris (Gen 8+) and Crocus (Gen4-Gen7) for Intel GPUs, radeonsi and r600 for AMD cards, nvc0 and nv50 for NVIDIA cards. Removing classic drivers will remove support for some older Intel GPUs (Gen2, Gen3), AMD Radeon R100 and R200, and older NVIDIA cards.
The Gallium3D architecture simplifies the development of Mesa drivers and eliminates the code duplication inherent in classic drivers. In Gallium3D, the tasks of memory management and interaction with the GPU are taken over by separate kernel modules DRM (Direct Rendering Manager) and DRI2 (Direct Rendering Interface), and drivers are provided with a ready-made state tracker with support for a reuse cache of output objects. Classic drivers require maintaining their own backend and state tracker for each hardware platform, but they are not tied to the Linux kernel DRI modules, allowing them to be used in OSes such as Solaris.
Source: opennet.ru