[ofa-general] More librdmacm stuff

[Doug Ledford]

On Thu, 2007-10-11 at 15:12 -0700, Sean Hefty wrote:
> Doug Ledford wrote:
> > OK, one of the issues I ran into was that in order to call
> > rdma_bind_addr(), you had to have an IP address to bind.  What if you
> > just want to run your RDMA devs without IPoIB?  An rdma_bind_dev() would
> > be useful.  Then, when a listen request comes in, knowing whether or not
> > the other end has an IP addr, whether or not your end has an IP addr,
> > and what they may be is buried inside cm_id->route->addr->src_addr and
> > cm_id->route->addr->dst_addr.  A couple wrappers to get at these in a
> > safe manner, and to possibly check that they are even valid at the same
> > time, would be good I think.  Also, I assume these are persistent
> > structs that won't be free()d out from under us, so I assume I can pass
> > those out to upper layers?
> 
> At the top level, the listen call operates on a 16-bit port value that, 
> for IB, is eventually mapped to a 64-bit service ID.  The connect 
> request targets a listen by IP address / port number.  The IP address is 
> used to identify the correct remote device.  How would the active side 
> locate the correct listener?

I'm more referring to when you call rdma_bind_addr to bind to your
device before you call rdma_connect.  In that instance, your address
isn't for the eventual destination, but just to bind you to your local
rdma device.  For that, an rdma_bind_dev that took an ibv context and a
port number on that device would avoid having to specify an IP address
that you don't really care about.

>   Or, are you only talking about loopback 
> connections on the same device?  (Hmm... maybe we can do something fancy 
> with loopback addresses which would avoid using IPoIB.)
> 
> The src/dst addresses are persistent once set, but I will add creating 
> wrapper functions to return them to my to-do list.
> 
> - Sean
-- 
Doug Ledford <dledford at redhat.com>
              GPG KeyID: CFBFF194
              http://people.redhat.com/dledford

Infiniband specific RPMs available at
              http://people.redhat.com/dledford/Infiniband
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