David Airlie Moves Toward Upstreaming Soft FP64 Support In Mesa

There's been work going on for years of "soft" FP64 support to allow emulated support for the double-precision floating-point data types for GPUs not otherwise inherently supporting this capability. The soft support would allow for some older GPUs to then advertise OpenGL 4.0+ support now that ARB_gpu_shader_fp64 support could be enabled. That day looks like it's finally coming for mainline Mesa...