I had some interesting hangs until I realised I should try flushing the
DDR FIFO register and lo and behold, hangs stopped occuring.
I've put in a few DDR flushes here and there in case people decide to
reuse some of these functions. It's very very likely they're almost
all superflous.
To test:
* Connect to a network with a _lot_ of broadcast traffic
* Do this:
# while true; do ifconfig arge0 down; ifconfig arge0 up; done
This fixes the mbuf exhaustion that has been reported when the interface
state flaps up/down.
d44d6b85dc