igb and ALTQ in 9.1-rc3

[Adrian Chadd]

The if_transmit versus multiqueue thing is orthogonal.

I'm planning to make net80211 and ath(4) use if_transmit instead of
if_start. It won't be a multi-queue driver; I'm actually going down
the path of if_transmit specifically so I can control the TX queue
serialisation and actively _serialise_ frame TX, instead of
implementing a multi-queue driver.

ALTQ as a concept needs to be glued in a different way. It can't just
override the queue macros like it does. That's just plain ew.

net80211 has some rather quirky behaviour, unfortunately. I won't go
into it here. Suffice to say, I can't just use the IFQ macros, the
if_queue as it stands, nor buf_ring.



Adrian