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

Jason Gunthorpe
2009-10-20T19:18:21Z

On Tue, Oct 20, 2009 at 12:13:03PM -0700, Sean Hefty wrote:
> >> rdma_bind_addr fills in the service id according RDMA IP CM service
> >> annex.
> >
> >Hm? If the sockaddr_ib contains the service ID why override it in the
> >kernel?
> >
> >The AF_IB/PS_IB flow in the kernel side must just use straight service
> >IDs.
>
> 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?

Is there any reason to ever use AF_IB/PS_TCP on the listening side?
What functional difference are you imagining compared to listening on
AF_INET/PS_TCP?

> interoperability. I realize that IB doesn't have the concept of a
> service ID for the active side of a connection, but the RDMA IP CM
> Service header carries the source port. And rdma_bind_addr is
> called by rdma_resolve_addr, so it needs to be updated.

Hmm, yes, messy..

> 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?

Jason