ixg and SFPs in NetBSD 10_RC1

Hi all,
I recently found a source of cheap second hand ixg(4) cards and so I've
started swapping out some Linux+Emulex/Mellanox for some NetBSD+Intel. 

When I plugged in one of my SFP+ DACs to the ixg I got the message
"Unsupported SFP+ module type was detected". That's a bit unfortunate
because I don't have a lot of SFP+ Fibre and I would much rather use
the DACs for the shorter connections. 

I did notice that the ixg has the device capability "ALLOW_ANY_SFP".
This sounds incompatible with the notion of an unsupported SFP. 

Does anyone have any idea what might be going on or any hints about
debug options I can turn on that won't drown me in cryptic messages? 

FWIW the ixg device is an 82599EB, so I think the card is an X520 of
some kind. The SFP+ DAC is a 1.2 m HP X240 cable. 

Cheers,
Lloyd