Re: Creating new RDMA driver for habanalabs

[Jason Gunthorpe <jgg@ziepe.ca>]

On Thu, Jul 07, 2022 at 12:30:03PM +0300, Oded Gabbay wrote:
> > >    These limitations are not relevant to a deployment where all the NICs are
> > >    Gaudi NICs, because we can use a single rkey for all MRs.
> >
> > Er, that is weird, did you mean to say you have only one MR per PD and
> > that it always has a fixed value?

> Not exactly. We have multiple MRs per PD, but the driver assigns the
> same rkey (fixed value) for all created MRs. Our h/w matches the rkey
> with the one that is written in the QP. The rkey is not part of the actual
> MMU translation that is done inside our h/w. The MMU translation is
> done using the PD (we call it ASID - address space ID) and Address.

I don't understand this at all - how can you have multiple MRs if
there is only one ASID per PD? The MR is logically the ASID since the
MR is the verbs model for MMU translation.

So, if you have one ASID per PD and multiple MRs, what are the MRs
supposed to be?

Jason