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

[Marek Olšák]

On Mon, Sep 4, 2017 at 3:56 PM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
> 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.

I can confirm with 100% certainty that PCIe 3.0 atomics aren't
required if you don't need them. In the majority cases, you don't need
them.

Marek