[Skiboot] nvlink2 topology

Reza Arbab arbab at linux.ibm.com
Thu Jul 26 03:53:00 AEST 2018

On Tue, Jul 24, 2018 at 12:12:43AM +1000, Alexey Kardashevskiy wrote:
>But before I try this, the existing tree seems to have a problem at
>(same with another xscom node):
>/sys/firmware/devicetree/base/xscom at 603fc00000000/npu at 5011000
>./link at 4/ibm,slot-label
>                 "GPU2"
>./link at 2/ibm,slot-label
>                 "GPU1"
>./link at 0/ibm,slot-label
>                 "GPU0"
>./link at 5/ibm,slot-label
>                 "GPU2"
>./link at 3/ibm,slot-label
>                 "GPU1"
>./link at 1/ibm,slot-label
>                 "GPU0"
>This comes from hostboot.
>Witherspoon_Design_Workbook_v1.7_19June2018.pdf on page 39 suggests that
>link at 3 and link at 5 should be swapped. Which one is correct?

I would think link at 3 should be "GPU2" and link at 5 should be "GPU1". 

If so, it's a little surprising that this hasn't broken anything. The 
driver has its own way of discovering what connects to what, so maybe 
there really just isn't a consumer of these labels yet.

Reza Arbab

More information about the Skiboot mailing list