hostapd dual band simultaneous

[Craig Johnson]

I apologize if this is an easy question, but I've been pulling my hair
out trying to figure out how to make this work.

I've got an AR9380 mini-pci card trying to make it work with hostapd
as an access point in both 2.4ghz and 5ghz simultaneously.  I can see
the bands in both 2.4 and 5ghz available, but of course I can only
select hw_mode=g or hw_mode=a.  I know this card can do them
simultaneously; the question is how do I configure it?  Launching
multiple hostapd daemons (one for 2.4, one for 5ghz) only makes them
step on each other.  Running latest hostap from git and a very recent
compat-wireless.

Any assistance would be greatly appreciated - I feel like I'm missing
something simple, but I haven't found a configuration to make this
work.