[ewg] bug 1918 - openmpi broken due to rdma-cm changes

[Steve Wise]

Sean Hefty wrote:
>> OpenMPI uses rdma_bind_addr() to figure out which ip addresses are valid
>> for which IB devices.   This logic is now broken.  Regardless of whether
>> OpenMPI should use another method for determining which IP address
>> belong to which interfaces, we should probably rethink whether we're
>> breaking rdma-cm semantics in a bad way on a point release.
>>     
>
> The changes to the rdma_cm have been merged upstream.  These were fixes
> specifically to enable using the loopback address with RDMA devices.
>
> At first thought, we can extend enum ib_device_cap_flags to indicate if a device
> supports loopback capabilities or not.  The rdma_cm could then skip over such
> devices when dealing with a loopback address. 
>
> - Sean
>   

But how can you determine _which_ rdma device should be used if and app 
binds to 127.0.0.1?  I think this is busted...