[openib-general] [RFC] [PATCH v2] rdma/ib_cm: fix APM support

[Michael S. Tsirkin]

Quoting Or Gerlitz <ogerlitz at voltaire.com>:
> the CMA API addressing is based on **IP** addresses, so when 
> a client connects it provides the IP address of the server and 
> optionally the its src IP as well.

Once we get the GID that matches the IP, we can locate an extra path and arm it.
Read up on how SDP does this in "A4.5.2 Automatic Path Migration": there are
several strategies there.

> Again, even with the second point being somehow solved, the apm nature 
> makes it a very limited in power feature of IB.

Protocols that rely on RC ACK for reliability guarantees (like SDP), basically
do not make it possible to address the hca failure case: you got an ACK, but
remote hca could have failed without committing data to memory. So APM failover
is a requirement for these. It could be iser does not need APM, fine.

-- 
MST