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

Jason Gunthorpe
2009-10-08T00:54:25Z

On Wed, Oct 07, 2009 at 05:38:27PM -0700, Sean Hefty wrote:
> >When used over IB, the IP address is little more than a qualifier contained
> >within the IB CM REQ private data.
>
> If we added support for AF_GID/AF_IB to the kernel, the rdma_cm
> could leave all of the private data carried in the IB CM REQ
> entirely up to the user. If the user happens to format that data to
> look like the CMA header, so be it. I believe this would allow for
> a 'clean' implementation of rdma_resolve_addr, preserve the ABI, and
> still allow a library to provide backwards compatibility.

Yep, not sure how you handle the listening side without port
conflicts?? But that doesn't seem to be a huge problem. TBH - since
ACM is kinda its own little world, it could just use a seperate
service ID space from RDMA CM?

> The following information should be known after calling
> rdma_resolve_addr: sgid, dgid, pkey, source port/sid, destination
> port/sid. The address structure for AF_IB should be defined to
> capture this information. (The port / service ID needs to be worked
> out.)

Yes, that seems great..

What API would you use to pass the PR data?

What do you think of a 'rdma_get_addr_info' that could be where libacm
hooks?

> Would this approach combined with the ability to set the route work for
> everyone?

'set the route' ?

You mean the 'ip route get' thingy?

Jason