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

[Aaron Watry]

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.

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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