[ofa-general] Re: [PATCH 3/3 v4] ib/ipoib: blocking multicast loopback ipoib packets

[Roland Dreier]

 > Probably, the least short-term pain (no ABI change) would be to use the last reserved
 > create-qp ABI byte for flags, while defining the flags field in
 > ibv_qp_init_attr as uint32_t (preparing for more than 8 future flags).

Actually there are tricks we could do to get more flag bits in the
kernel ABI... eg set a bit in the reserved part to indicate "flags are
present", and then stick the flags in srq_handle if is_srq is not set,
and in max_recv_sge if it is set.

 > Adding the flags field to the qp_init_attr structure does, however, require incrementing the
 > libibverbs version to 1.2, necessitating an IBVERBS_1.1 compatibility layer.

This actually seems like much more of an issue.  Especially since
librdmacm calls ibv_create_qp.

 - R.