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

[Steve Wise]

Or Gerlitz wrote:
> Steve Wise wrote:
>> Sort of.  It is not exactly a dma_mr.  dma_mrs allow remote IO.  The 
>> zero-stag is an iWARP verbs concept.  zero-stag can be used by kernel 
>> users as the lkey in any SGE that requires only local access rights.  
>> If the lkey is zero, then the rnic interprets the addr field in the 
>> SGE as a bus address.
>>
>>
> I see.
>
> Assuming we want to narrow the differences between RDMA transports 
> from the ULP point of view and that IB does not support this verb - 
> I'd like to see if its possible to have zero stags implemented as dma 
> mrs.
>
> How about enhancing the iWARP HW drivers implementation of get_dma_mr 
> to switch on the access flags provided by the caller, and if no remote 
> access it needed, just return zero stag for mr.lkey without doing any 
> registration.
>
I think that sounds reasonable.  I can add that for chelsio.

Steve.