[ofa-general] [PATCH RFC] rds: add iwarp support

[Steve Wise]

Just for the record, there are a few coding todos remaining once we get 
the main merged IB/IW transport:

1) Make use of the local_dma_lkey if the device supports it.  This lkey 
can be used in the SGL entries for SEND, RECV, and the source of a WRITE.

2) Get rid of the dma_mr usage for the sink of an RDMA READ.  For iWARP, 
the sink of a read requires REMOTE_WRITE access, and we do not want to 
expose all of memory for remote I/O.  The transport will have to use a 
fastreg mr for these.  This is potentially iwarp-only logic since IB 
allows an lkey for the sink of a READ.

Implementing both of these will allow the iwarp logic to not depend on 
dma mrs at all.  This is desirable for the cxgb3 device which has 
limitations on dma mrs.


Steve.