[ofa-general] [PATCH RFC] RDMA/cxgb3: Fixes for zero-stag.

[Or Gerlitz]

Steve Wise wrote:
> NFSRDMA was planning on using the zero stag for recvs on iwarp 
> transports.  This boils down to only needing the zero stag + fastreg 
> mrs for NFSRDMA server over T3, avoiding dma_mrs which have limits in 
> the T3 HW.
>> the zero STag breaks the semantics slightly in that there is no 
>> longer any PD attached to the key returned by ib_get_dma_mr 
Steve,

I am fine with the approach of new verb, however, I still want to make 
sure that this can be used under a unified IB/iWARP design of a ULP 
without much pain... the kernel ULPs: rNFS, iSER initiator (Lustre, RDS, 
etc) use the dma mr for recv nd send work-requests.

So how you envision the ULP code in the presence of the new verb - is it 
the ULP to check if the device supports the capability and if yes, use 
dev->local_dma_lkey else call get_dma_mr and use the returned lkey?

in you comment above you say "using the zero stag for recvs on iwarp 
transports" does zero stag applies also to sends? if not, will sends use 
dma-mr?

Or.