[Solved] WebGL stops working randomly in Chromium and Firefox

Question

Hi
I'm using a Thinkpad x220 with an Intel GMA 3000 chipset, using the xf86-video-intel 2.99.912-2 driver for X11 and mesa 10.2.4-1 for OpenGL.
OpenGL is detected and working fine locally, glxinfo lists it, glxgears runs as do OpenGL-based games.
Yesterday, I updated my graphics drivers and now WebGL is not working most of the time.
When I open http://doesmybrowsersupportwebgl.com/ right after starting X11, it shows 'Yay' and lists the details of the WebGL capabilities of the browser. However, when I refresh the page a few times and/or restart the browser, it stops working and shows 'Nay'.
I will try downgrading the packages to see if this is actually related to the update (I never consciously used WebGL before so the issue may have been there for a while). I also tried fiddling with WebGL/GPU-related settings
chrome://flags
(Chrome) and
about:config
(Firefox) but that had no influence whatsoever and since it works sometimes I don't think it's a browser isseu.
What could be the cause of this and where should I look for clues? If the GPU crashed, X11 would crash as well, wouldn't it? Can I make error messages emitted by the graphics driver appear in the Xorg log files? Did anyone here have a similar issue with the same chipset or not have the issue with a different setup?
Thanks very much for any responses!
> glxinfo | grep "OpenGL version"
OpenGL version string: 3.0 Mesa 10.2.4
> uname -a
Linux hermes 3.15.5-2-ARCH #1 SMP PREEMPT Fri Jul 11 07:56:02 CEST 2014 x86_64 GNU/Linux
> chromium --version
Chromium 36.0.1985.125
> cat /etc/X11/xorg.conf.d/10-intel-font.conf
Section "Device"
Identifier "Intel"
Driver "intel"
# Option "AccelMethod" "uxa" # made no difference
# Option "AccelMethod" "sna" # default
# Option "AccelMethod" "glamor" # X11 won't start
# Option "DebugWait" "true" # made no difference
EndSection
Last edited by kba (2014-07-25 14:25:44)

Answer 1

For all the folks who might run into the same issue: The problem was that the environment variable
LIBGL_ALWAYS_INDIRECT=1
is being set by compiz, my window manager (see https://bugs.launchpad.net/ubuntu/+sour … comments/4. Now, when I start any program, such as a terminal or a browser, from compiz using key bindings, direct rendering to the graphics card is disabled and so is WebGL.
The fix was to disable 'Indirect Rendering' using either Compiz Fusion Icon or by setting the env var before compiz starts.