Airlie Is Looking At Tournier's Soft FP64 Work For R600-Rats

Written by Michael Larabel in Mesa on 27 May 2017 at 10:23 AM EDT. 7 Comments
A few days ago I wrote about David Airlie's work on a new "r600-rats" branch where he's working on bringing up OpenGL 4.2 support to more Radeon HD 5000/6000 series hardware on R600g that's currently limited to OpenGL 3.3. Some questions arose about the FP64 support.

The lack of native FP64 support for most hardware in R600g (with the exception being just the HD 5800/6900 series on R600g right now) is what's left the driver at exposing just OpenGL 3.3 support. Airlie has been working on getting this hardware to OpenGL 4.2 in part by having soft/fake FP64 support. In the earlier article some Phoronix readers were wondering whether Airlie was making use of Elie Tournier's "soft FP64" code to handle it in just GLSL.

Elie Tournier is the former GSoC student developer now working for Collabora who was working on soft FP64 support to help older hardware in Mesa and has made progress although none of the work is presently in mainline Mesa Git.

This week on the Mesa mailing list, Airlie started a discussion about soft FP64 on Evergreen (Radeon HD 5000 series). In there he mentions of looking at Elie's soft FP64 work but was inquiring regarding some issues that were noticed in the debug build.

Hopefully this r600-rats work will get into shape soon. I do intend to eventually run some r600-rats benchmarks on older HD 5000/6000 series hardware once the support is more into shape and less hackish -- perhaps around the time of Phoronix's 13th birthday benchmarking.

Those wanting to try out the code in its present state can clone from r600-rats.
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Michael Larabel

Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

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