They did it. A smallish OpenCL example running on Mesa's r600.

::: {.separator style=”clear: both; text-align: center;”} :::

\ This happened somewhat unexpected while looking again at the state of open OpenCL implementations (so pocl and clover).\ \ Suddenly some hero told me that there is a smallish OpenCL example which actually works with Mesa’s OpenCL implementation (actually this is bound to r600 based devices). So what is awesome if this ain’t?\ \ What you need:\

  • tstellar’s clover-r600-master branch
  • Fedora 16 (okay, it might also work somewhere else), with rawhide clang and llvm
  • and the example code
  • oh - and - important -  an appropriate card e.g. HD6310 (AMD E-350/E-450) or some other evergreen GPU

\ What actually has to be done is - this time - left to the user.\ A few hints:\

  • Look at the comment in line 96 of src/gallium/state_trackers/clover/llvm/invocation.cpp and swap comments (there are r600 patches for LLVM which can be applied to get around this).
  • The implementation expects the opencl libs to reside in /usr/local/lib/opencl - so install or softlink
  • Set LD_LIBRARY_PATH to mesa/lib when building the example
  • You need to provide the OpenCL headers

The present support is currently just basic, but it’s awesome to see this progress.\ \ What you get:\ \

There are 1 platforms.
There are 1 GPU devices.
clCreateContext() succeeded.
notkernel
main
clCreateCommandQueue() succeeded.
clCreateProgramWithSource() suceeded.
build log:
clBuildProgram() suceeded.
clCreateKernel() suceeded.
clCreateBuffer() succeeded.
clSetKernelArg() succeeded.
--------------------------------------------------
[...]
clEnqueueReadBuffer() suceeded.
pi = 3.141590

\ Let’s see when I can build gst-plugins-opencl against mesa. And “they” include zack, steckdenis, and tstellar.\ \ Some more informations using this tool:\

$ make clInfo CFLAGS="-I$PATH_TO_CL_HEADERS" LDFLAGS="-lOpenCL -L$MESAPATH/lib"
$ sudo LD_LIBRARY_PATH="$MESAPATH/lib" ./clInfo
Found 1 platform(s).
platform[(nil)]: profile: FULL_PROFILE
platform[(nil)]: version: OpenCL 1.1 MESA 8.0.0
platform[(nil)]: name: Default
platform[(nil)]: vendor: Mesa
platform[(nil)]: extensions: 
platform[(nil)]: Found 1 device(s).
[...]

::: {#footer} [ March 5th, 2012 5:43pm ]{#timestamp} [clover]{.tag} [mesa]{.tag} [fedora]{.tag} [opencl]{.tag} :::