[ofa-general] Re: does the mlx4 low level driver support working with multicast groups from user level?

[Roland Dreier]

 > When i executed ibv_devinfo and checked the multicast props of the
 > device i got the following values:
 > 
 > sw180:~ # ibv_devinfo -v | grep cast
 >    This will severely limit memory registrations.
 >        max_mcast_grp:                  8192
 >        max_mcast_qp_attach:            0
 >        max_total_mcast_qp_attach:      0
 > 
 > It seems that the IB low level driver (drivers/infiniband/hw/mlx4)
 > doesn't fill the attribute max_mcast_qp_attach.

Yes, that code is missing.

 > When i tried to use multicast groups from user level i got weird failures.
 > 
 > Does the low level driver support working with multicast groups from
 > user level?

There's nothing special to do to handle userspace multicast groups.
The multicast groups work well enough for IPoIB to work for me, but I
haven't done any real testing.

It should work but there's probably a silly bug somewhere.  I just
fixed one such bug but without knowing what your weird failures are,
it's hard to say whether it would affect your tests.

 - R.