https://bugs.freedesktop.org/show_bug.cgi?id=70706
--- Comment #8 from Dennis Schridde devurandom@gmx.net --- (In reply to comment #7)
(In reply to comment #5)
To me this issue seems to appear randomly - sometimes KDE starts with working compositing, but most often it does not.
Same, here. When it starts _with_ compositing, then error message appears. _Without _ compositing glxinfo runs OK and GL performance is nearly 25% better!
In the current session I did not get compositing but the mentioned message in ~/.xession-errors: kwin(2492): Failed to get visual from fbconfig kwin(2492) KWin::OpenGLBackend::setFailed: Creating the OpenGL rendering failed: "Could not initialize the buffer" kwin(2492): Failed to initialize compositing, compositing disabled
glxinfo currently does not work, either: Error: couldn't find RGB GLX visual or fbconfig Error: couldn't find RGB GLX visual or fbconfig name of display: :0 [...]
So the current session seems to be a case of "without compositing, with glxinfo error". Which also seems to make sense: Something is preventing GL apps from working, which also affects glxinfo.
A quick test shows that EGL does not seem to be affected: $ eglinfo EGL API version: 1.4 EGL vendor string: Mesa Project EGL version string: 1.4 (Gallium) EGL client APIs: OpenGL OpenGL_ES OpenGL_ES2 [...]
Also the X11 variants of the *gears (egl,es1,es2) programs work: $ eglgears_x11 EGL_VERSION = 1.4 (Gallium)
But the "screen variants do not (though I do not remember ever before testing them, so I cannot tell whether this is a regression): $ eglgears_screen EGL_VERSION = 1.4 (Gallium) EGLUT: failed to choose a config
I can confirm this with KWin (stripped from unrelated output): $ kwin kwin(3945): Failed to get visual from fbconfig kwin(3945) KWin::OpenGLBackend::setFailed: Creating the OpenGL rendering failed: "Could not initialize the buffer" QObject::connect: Cannot connect (null)::resetCompositing() to KWin::Compositor::restart() kwin(3945): Failed to initialize compositing, compositing disabled kwin(3945): Consult http://techbase.kde.org/Projects/KWin/4.0-release-notes#Setting_up
$ kwin_gles OpenGL vendor string: X.Org OpenGL renderer string: Gallium 0.4 on AMD REDWOOD OpenGL version string: OpenGL ES 3.0 Mesa 9.2.4 OpenGL shading language version string: OpenGL ES GLSL ES 3.0 [...]
So is there a possibility, that we can disable compositing on the fly, when GL apps starts?
I think that is a completely unrelated issue that belongs on https://bugs.kde.org/ and should be reported against KWin.