[openib-general] [PATCH][RFC] CMA automatic port number assignment

[Sean Hefty]

James Lentini wrote:
> When the CMA automatically generates a port number, does it
>  1) coordinate with the native transport (TCP/UDP/SCTP) stack? or

No - the CMA port spaces are separate from the TCP/UDP/SCTP port spaces for IB. 
  This is why it doesn't bother generating a local port number.  Doing so isn't 
really needed.

>  2) coordinate across RDMA transports (IB and iWARP)? or

Not really, because iWarp will have true IP port spaces, whereas, IB only 
pretends to have them.  There is a sort of coordination across all transports 
for listening requests.

> For IB, the CMA can guarantee #3 relatively easily. If this is going 
> to be an issue for iWARP, it is acceptable for the CMA to only 
> guarantee #4.
> 
> Do you agree Sean?

The real issue is that the CMA port spaces are not IP port spaces for IB.  On 
the active side of the connection, we can use any number that's convenient.  If 
we want to assign different port numbers to different connections, then the QPN 
should work fine.

What the underlying issue that you're trying to solve?

- Sean