[Mesa-dev] OpenCL Support on older AMD GPUs

Jan Vesely jan.vesely at rutgers.edu
Thu Aug 23 21:44:51 UTC 2018

On Thu, 2018-08-23 at 18:11 +0300, Benson Muite wrote:
> Hi,
> Is there likely to be support for OpenCL on older AMD GPUs? I have tried 
> running an OpenCL benchmark 
> (https://github.com/mpicbg-scicomp/gearshifft) on an AMD A6-6420K APU 
> running Fedora 28. The code seems to partially run, but gives incorrect 
> results.
The righland APU uses VLIW4 architecture and afaik, no one with such
card has worked on clover, so bugs are expected.

was there any error during compilation or did all kernels compile OK?

> Would it be challenging to add full OpenCL 1.1 support? The GPU 
> of particular interest to me is Radeon HD 8470, caicos, which appears to 
> have WIP:
> https://www.x.org/wiki/RadeonFeature
> How can one help move this forward?

One immediate thing to try is to run with more up to date libclc[0].
It has seen quite a lot of activity earlier this year, and last time I
checked Fedora has not picked that up.

If that does not help, then the LLVM generates wrong code.
identifying the wrong parts and sendinng an LLVM patch (or even
reporting bug) would help there.

Contributions to LLVM would need some level of understanding the ISA
(see documents that Alex pointed to [1,2])


[0] https://git.llvm.org/git/libclc
[1] http://developer.amd.com/wordpress/media/2012/10/AMD_Evergreen-Fam
[2] http://developer.amd.com/wordpress/media/2012/10/AMD_HD_6900_Serie

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Jan Vesely <jan.vesely at rutgers.edu>
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