Gallium 0.4 on llvmpipe (LLVM 3.4, 128 bits) , 3.0 Mesa 10.2.8 - the last one that could use Firefox in Windows XP
how to install:
https://download.qt.io/development_releases/prebuilt/llvmpipe/windows/ file opengl32sw-32.7z (25-Sep-2014 14:30)
rename opengl32sw.dll in opengl32.dll
move file opengl32.dll in browser folder, example C:\Program Files\Mozilla Firefox the browser will automatically see this file and use it as an OpenGL driver file
example, For Webrender, Firefox immediately tries to use opengl32.dll
In order for the browser to use opengl32.dll for WebGL, you need to toggle these options
webgl.disable-angle — true
webgl.force-enabled — true
gfx.prefer-mesa-llvmpipe — true