[openib-general] RDMA connection and address translation API

[Guy German]

> What do you think about this flow ? 
> 1. resolve device and port from ip address - synchronous operation 
>    (like at.c resolve_ip)
> 2. rdma_create_qp (device+port) - modifies qp to init with 
> default pkey index 
> 3. ib_post_recvs(...); 
> 4. cma_connect -  asynchronous at, modify qp with correct 
> pkey index, cm_connect

Caitlin wrote:
>At least with iWARP a QP is not bound to a specific port, or even
>to an IP Address. It is only bound to the RDMA Device (RNIC) and
>Protection Domain. The same QP can be re-used for a new connection
>with a new IP address. Indeed, that is exactly what would happen
>with application-layer controlled failover (such as iSER).

In ib, in order to post receive the QP need to be in init.
In order to modify qp to init, you need port and pkey_index.
If iWARP can post receive without it, the iwarp implementation
of "rdma_create_qp" can ignore the port attribute.

The other option, that was suggested to solve the sync problem
(need of post receive before connect) is to retrieve the path
synchronically, which will require an unnecessary upcall handling
for iwarp consumers.

Guy