Once the splitting of the SceneOpenGL (https://git.reviewboard.kde.org/r/106357/) is merged into master, the SceneOpenGL2 can disable itself for specific drivers (supported method). For that the GLPlatform should recommend one of the versions specific for the given hardware/driver combination. E.g. if the driver does not support OpenGL 2 it's better to use the OpenGL 1 code path even if the shader extensions are supported (see BUG #300901).
commit e1d7bfa55663e3fb017bd088c9292e134327d9ce Author: Martin Gräßlin <mgraesslin@kde.org> Date: Fri Oct 5 18:00:49 2012 +0200 GLPlatform can recommend the compositor to use During detecting the OpenGL capabilities also a recommended compositor can be set. This recommendation is honoured by the OpenGL based compositors. That is the SceneOpenGL2 requires a recommendation for at least OpenGL2 and the SceneOpenGL1 requires at least a recommendation for OpenGL1. If the driver recommends XRender compositing the SceneOpenGL performs the existing fallback to XRender. With this recommendation the hacks in the Scene are removed, e.g. it is no longer checked whether the driver is software emulation as that is provided through the recommendation. To overrule the recommendation the environment variable KWIN_COMPOSE is extended by the values O1 and O2 to enforce either OpenGL 1 or OpenGL 2. This overwrites all other checks. As a side-effect this allows now to run KWin on the llvmpipe: LIBGL_ALWAYS_SOFTWARE=1 KWIN_COMPOSE=O2 kwin --replace & But not that I would recommend to use it :-) REVIEW: 106741