[openib-general][RFC]: CMA IB implementation

[Sean Hefty]

Guy German wrote:
> I believe that ib_at is still a valuable module even if ATS reverse ARP 
> is broken, and I think we should discuss this.

Here's my thinking on this.  ATS is broken as you mentioned for reverse lookups. 
  However, if we want to keep ATS, I think that ATS registration/deregistration 
should be integrated with IPoIB.  To keep it separate, we will need to patch 
net_device to provide an rdma_ptr as suggested by Roland.

For ARP, we can extract ARP code from ib_at and use it with the CMA.  The CMA 
can then use the "ib_arp" module to map network addresses to GIDs, then issue 
path record queries using ib_sa.

Any caching should be done in other places.  For example, ARP already does its 
own caching, and I believe that a generic SA caching module should be a part of 
ib_sa or exist separately.

This seems the best approach to getting a higher level RDMA connection interface 
into the kernel.

- Sean