Using a locally built libOSMesa to enable WebGL in Firefox?

Question

Well, I wanted to try to check out WebGL on Firefox (v38.0.5 on Linux); and I realized that in about:config, webgl.osmesalib was set to /usr/lib/libOSMesa.so.6, while about:support claimed:

Graphics
--------

Adapter Description: Tungsten Graphics, Inc -- Mesa DRI Intel(R) IGD GEM 20100330 DEVELOPMENT x86/MMX/SSE2
Device ID: Mesa DRI Intel(R) IGD GEM 20100330 DEVELOPMENT x86/MMX/SSE2
Driver Version: 1.4 Mesa 7.10.2
GPU Accelerated Windows: 0/1 Basic Blocked for your graphics card because of unresolved driver issues.
Vendor ID: Tungsten Graphics, Inc
WebGL Renderer: Blocked for your graphics card because of unresolved driver issues.
windowLayerManagerRemote: false
AzureCanvasBackend: cairo
AzureContentBackend: cairo
AzureFallbackCanvasBackend: none
AzureSkiaAccelerated: 0

So, I found Blocklisting/Blocked Graphics Drivers - MozillaWiki, which notes:

Mesa drivers are whitelisted if the Mesa version is at least 7.10.3 (see bug 659560).

Exception: with the Nouveau 3D driver, the Mesa version is required to be at least 8.0 (see bug 729817)

Right, so libOSMesa.so.6 doesn't actually check out with 1.4 Mesa 7.10.2, but I thought I'd rebuild from source anyways.

So I got the source of 7.10.3 (MesaLib-7.10.3.tar.gz, MesaGLUT-7.10.3.tar.gz) and libdrm-2.4.24, unpacked, ran PKG_CONFIG_PATH=/path/to/Mesa-7.10.3/libdrm-2.4.24 ./configure --enable-gl-osmesa and make, and indeed, I do get shared library files built libOSMesa.so -> libOSMesa.so.7 -> libOSMesa.so.7.10.3; and if we doubt the version info in the filename, we could also try this:

$ strings -a lib/libOSMesa.so.7 | grep 'Mesa 7'
%u.%u Mesa 7.10.3
OpenGL ES-CM 1.%d Mesa 7.10.3
OpenGL ES 2.0 Mesa 7.10.3

Nice, so now I thought, I'll just replace this library as webgl.osmesalib:

... and run Firefox with:

LD_LIBRARY_PATH=/path/Mesa-7.10.3/lib LD_PRELOAD=/path/Mesa-7.10.3/lib/libOSMesa.so.7 strace /path/to/firefox -P default -safe-mode -new-instance 2>&1 | grep --color=always 'Mesa.*\.so'

... and strace even tells me the library has been opened:

open("/path/Mesa-7.10.3/lib/libOSMesa.so.7", O_RDONLY) = 4

... and still - I get this in about:support, the same as above:

So, it's still referring to Mesa 7.10.2, regardless - and I have no idea why?

Btw, I just now realized that the config setting webgl.osmesalib may be something hanging in my profile from earlier versions, because if I start firefox with default profile and safe mode, all I get is gfx.blacklist.suggested-driver-version and gfx.prefer-mesa-llvmpipe settings:

So - how can I persuade firefox, to try the newly built Mesa libraries, instead of the old ones?

Answer 1

Ok, I think I understand now: as per Enable OpenGL 2.0 and WebGL for Intel GMA3150 in Ubuntu, what this new Firefox sees as a Graphics driver, is not some specific file version, but that which is reported by glxinfo:

$ glxinfo | grep -i "OpenGL version"
flushing GPU caches before/after each draw call
OpenGL version string: 1.4 Mesa 7.10.2

Then I configured again with a prefix /usr (otherwise the default is /usr/local), which is where Ubuntu Natty wants these stored; and did install:

./configure --enable-gl-osmesa --prefix=/usr
sudo make install

And then, just for a while, glxinfo returned 7.10.3, which is what Firefox would have seen; but for one I ran out of disk space; and for another, now after reboot I get:

$ glxinfo 
name of display: :0.0
Error: couldn't find RGB GLX visual or fbconfig

And this apparently (graphics - Error: couldn't find RGB GLX visual or fbconfig ubuntu 12.04) requires messing with xserver-xorg, so it is a bit more complicated than just replacing the library, it seems...

---

Edit: actually got it: From this Problems with nvidia drivers in 12.2 - glxinfo "couldn't find RGB GLX visual", I learned to do:

$ grep -B2 EE /var/log/Xorg.0.log
...
[    37.353] (II) AIGLX: Trying DRI driver /usr/lib32/dri-alternates/i915_dri.so
[    37.353] (II) AIGLX: dlopen of /usr/lib32/dri-alternates/i915_dri.so failed (/usr/lib32/dri-alternates/i915_dri.so: cannot open shared object file: No such file or directory)
[    37.353] (EE) AIGLX: reverting to software rendering
...

I mentioned that I ran out of disk space; so I did this (after a sudo make install of Mesa):

sudo mv /usr/lib/dri /media/external/_mv/
sudo ln -s /media/external/_mv/dri /usr/lib/
sudo mv /usr/lib/egl /media/external/_mv/
sudo ln -s /media/external/_mv/egl /usr/lib/

Then we actually need to restart x-server, so it can "see" the .so files in the symlink locations upon load, which as per How can I restart x-server from the command line? - Ask Ubuntu, for me was sudo service gdm restart

After that, got this:

$ LIBGL_DEBUG=verbose glxinfo
name of display: :1.0
libGL: OpenDriver: trying /usr/local/lib/dri/i915_dri.so
libGL error: dlopen /usr/local/lib/dri/i915_dri.so failed (/usr/local/lib/dri/i915_dri.so: cannot open shared object file: No such file or directory)
libGL error: unable to load driver: i915_dri.so
libGL error: driver pointer missing
....

... and simply did:

sudo ln -s /media/external/_mv/dri /usr/local/lib/

... and voila:

$ LIBGL_DEBUG=verbose glxinfo
name of display: :1.0
libGL: OpenDriver: trying /usr/local/lib/dri/i915_dri.so
libGL: Can't open configuration file /etc/drirc: No such file or directory.
libGL: Can't open configuration file /etc/drirc: No such file or directory.
flushing GPU caches before/after each draw call
display: :1  screen: 0
direct rendering: Yes
...

... except, not even this is good enough for this Firefox:

Ah, well...