Airlie Moves Ahead With His Plan For Soft FP64 For Mesa, OpenGL 4.3 For Evergreen GPUs

Written by Michael Larabel in Mesa on 13 March 2018 at 05:47 AM EDT. 8 Comments
Yesterday we wrote about David Airlie working on a fresh push to get "soft FP64" support in Mesa for allowing some older graphics cards on the R600g driver to then have OpenGL 4 support thanks to this double-precision floating-point support being their last blocker. That code is moving forward.

The soft FP64 support within GLSL shaders is the work originally done by former GSoC contributor Elie Tournier. Airlie is preparing to merge that code along with various changes he has made since then, including the option for Gallium3D drivers to individually decide about opting in or not to this emulated FP64 support.

With this he's hoping to enable OpenGL 4.3 support for all GPUs on R600g back to Evergreen (Radeon HD 5000 series) where as now they are mostly at OpenGL 3.3 except for the HD 5800/6900 series having native FP64 support. Airlie commented on the 50 patches, "I'm not really interested in bikeshedding the nitty gritty details of the fp64 emulation, the main goal for this code is to provide the fp64 bit so we can enable GL4.3 on evergreen GPUs, I don't think anyone is going to use it that often in practice, and if we can get it to the level that passes conformance (still WIP) then I'll be happy. I think optimising it to reduce CPU usage at compile time is way more important than optimising it to reduce GPU usage."
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