[Mesa-dev] What is the difference between ROCm and Clover?

[Nicolai Hähnle]

On 04.09.2017 15:38, Aaron Watry wrote:
> On Sun, Sep 3, 2017 at 3:20 PM, David Niklas <doark at mail.com> wrote:
>> Hello,
>> I'm interested in knowing why there are two different OpenCL
>> implementations of OpenCL drivers for AMD cards.
>> Is it because they support different ASICs?
>> One is older and going to be replaced?
> 
> As near as I can tell, ROCm requires PCIe 3.0 Atomic operations for
> both the CPU and GPU.  As such, ROCm will never support the VLIW
> radeons (5000-6000 series) or the earlier generations of GCN (SI, CI,
> possibly VI?). According to the ROCm page, it requires
> Fiji/Polaris/Vega.  It also requires either a Haswell or Ryzen CPU (or
> newer), so anyone with an older CPU will be left out of ROCm support.
> External GPUs via Thunderbolt 1/2 enclosures are also unsupported.

For what it's worth, if you have an "older" system without PCIe 3.0 
atomics, you could still try and see how far you get with ROCm. As long 
as you don't *actually* need atomics between the CPU and GPU in your own 
code, you're probably fine. I've never tried it, though.

Cheers,
Nicolai


> 
> There is a bit of overlap between the two projects, in that
> Clover/libclc supports Polaris cards on various CPUs, but it's safe to
> say that for the moment, if your system is supported by ROCm, it is
> the more complete/well-tested option. Clover/Libclc are both still
> works in progress that work for some use cases, but they are not
> complete, and have never passed a run of the CL 1.2 conformance test
> suite in any configuration, and it's definitely a use at your own risk
> type of thing for now.
> 
> --Aaron
> 
>>
>>
>> Thanks,
>> David
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