[openib-general] RDMA CM multicast

[Sean Hefty]

> Doesn't this carve a hole in the IPv6 (multicast) address space (group
> ID) ? If so, is that a hole we can carve out ?

I don't think that this causes any issues that weren't previously there.  IPOIB 
maps an IPv6 address into 80-bits, so not every IPv6 address can be mapped into 
an MGID using the ipoib algorithm.

What the rdma_cm needs to determine is whether the sockaddr passed into 
rdma_join_multicast is an IPv6 address that needs to be translated into an MGID, 
or whether the address is itself an MGID.  I guess that it might be able to look 
at the address to see if it matches the SA created MGID format (0xff1?a01b...).

- Sean