[openib-general] Re: [PATCH] CMA and iWARP

[Caitlin Bestler]

Steve Wise wrote:
>> A direct link from the net device to 0 or 1 rdma device would be
>> better, but if doing it by search then the "mac address"
>> for iWARP should be the IP address -- not the Ethernet address.
> 
> Why?

Because an iWARP device can encompass multiple Ethernet ports
with the same mac address. If they do not have a different IP
address then there is no reason for the consumer to understand
that they are distinct physical ports.

The starting point here is the socket model, where the consumer
is not even aware of which Ethernet NIC they are using by
default. We are disturbing that model by saying that you
have to know which RDMA device so that memory can be registered.

We should not go more fine-grained than that.

Doing so is complicating the programming model, and interferes
with existing port-failover solutions already deployed in the
Ethernet space.