Phoronix: How To Begin Using OpenCL With Radeon Gallium3D
Earlier this month I wrote about how you can sort of begin using OpenCL acceleration out of the Radeon Gallium3D driver, but in the short time since, the code has continued to advance and now here's a guide for trying out this GPGPU computing technology on the open-source Radeon Linux driver...
I built a copy of this late last week, and got it working on my Radeon 6850 after a few small patches from Tom (clover had been detecting my gpu as a cayman, not Barts).
I've gotten it working with Tom's opencl-example programs (if you're running X as root, you need to run those programs as a root user if you want the device discovery to work correctly). More advanced examples aren't currently running (such as the WebM OpenCL decoder I wrote for my thesis), but it's just a matter of time. I'll have some time this week to triage where my code is failing, and maybe I can provide a few patches to help get things fixed/implemented in clover.
1) You really do need a kernel that's 3.1+. I tried in 3.0.x (Ubuntu 11.10) and dmesg reported errors from rejected CS packets.
2) If you get an error -13 message with PCI ID quote in it when running the example programs, you're probably not running them as root... You're being cryptically told that you've been denied permission to open that device because it's open by another user.
3) Otherwise it wasn't too hard to get up and running. You'll need lots of development packages/headers installed, and it might not hurt to install xorg-edgers if you're running Ubuntu or a derivative, as you'll need some relatively recent libdrm bits.