IF_ADDR_UNLOCK() across network device drivers when accessing the
per-interface multicast address list, if_multiaddrs. This will
allow us to change the locking strategy without affecting our driver
programming interface or binary interface.
For two wireless drivers, remove unnecessary locking, since they
don't actually access the multicast address list.
Approved by: re (kib)
MFC after: 6 weeks
macio's enable-enet word, which apparently does nothing on some machines,
open an OF instance of the ethernet controller. This fixes cold booting
from disk on my Blue & White G3.
MFC after: 3 days
