RE: [PATCH 2/2] rdma/cm: allow user to specify IP to DGID mapping

Sean Hefty
2009-10-20T20:05:15Z

>> I agree. But we can still support AF_IB/PS_TCP by simply assigning
>> the service ID correctly. rdma_bind_addr only needs to fill in a
>> service id if one is not given. This should enable
>
>'one is not given' == 0 service ID?

yes

I'm guessing PS_IB would need to assign from the IB CM assigned range starting
at 0x020::0 to avoid conflicts.

>Is there any reason to ever use AF_IB/PS_TCP on the listening side?

I don't think so. I was thinking of this combination on the active side in
order to get the port number to place in the private data.

>What functional difference are you imagining compared to listening on
>AF_INET/PS_TCP?

I hadn't thought about this, but making stuff up, I guess this could allow using
the rdma_cm without ipoib running...? From IB's perspective, PS_TCP is just a
specific subset of the service ID range.

>> Even once PS_IB is added, we need to make sure that it doesn't collide with
>> PS_TCP at the IB service ID level, or IB will be in the same situation that
>> iWarp is in with space collisions.
>
>I thought there was already a single service ID registration list that was
>shared between RDMA CM and IB CM?

Not really - the rdma cm constructs the service id, and the ib cm checks that
it's usable, but not until listen is called.