[Skiboot] [RFC PATCH skiboot] npu2: Add nvlink2 interconnect information

Alexey Kardashevskiy aik at ozlabs.ru
Thu Aug 16 17:08:39 AEST 2018

On 16/08/2018 15:38, Andrew Donnellan wrote:
> On 15/08/18 18:26, Alexey Kardashevskiy wrote:
>> GPUs on Redbud and Sequoia platforms are interconnected between each
>> other in groups of 2 or 3 GPUs. The problem with that is if we decide
>> to pass one of GPUs in a group to the userspace (and potentially a
>> guest),
>> we need to make sure that interconnectd link does not get enabled.
>> The GPU firmware provides a way to disable links on a GPU. However we
>> want to disable only links to other GPUs which are not in the same guest
>> so we need a map of what nvlink is connected to what.
>> This adds an "ibm,nvlinks" property to every GPU in a "GPUn" slot
>> with phandles to peer GPUs and NPU PHB, the index in the property is
>> GPU's
>> link number.
>> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> Would we be able to use a more descriptive name like
> "ibm,nvlink-peer-devices" or something?

"ibm,nvlink-peers" may be (shorter) but yes, good point.


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