[openib-general] rdma_cm branch

[Michael S. Tsirkin]

Quoting r. Sean Hefty <sean.hefty at intel.com>:
> Subject: Re: rdma_cm branch
> 
> >> The ideal fix for this is to include rdma_conn_param as part of the
> >> rdma_cm_event.
> >
> >BTW, wouldn't it be cleaner to just pass it up in the request event?
> 
> Yes - this is what I meant by including it in the rdma_cm_event structure.
> 
> >> However, this breaks every userspace app that's been coded to
> >> OFED / SVN.
> >> An alternative is to add another call to retrieve the data, but
> >> that's not a very clean alternative for new kernel submission.
> >
> >Another alternative is to version the create ID call.
> 
> Hmm... I need to think about the implementation of this more, but this sounds
> like a possibility.  Can you provide any details on how you're envisioning this
> working?

Well, I have not thought this through yet, but suppose you extend
struct rdma_ucm_create_id, and check the length parameter in
ucma_create_id to figure out which format was used.

If length is small, you know you have userspace with old ABI.

An extra field could be a userspace ABI version number, which you
then carry around and use to figure out how to decode the
resst of the stuff that comes from userspace.


-- 
MST