problems:
1) Add locking for SMP, code provided by Alan Cox
2) While testing Alan's patches, I observed serious problems with
the jumbo buffer allocation code (machine crashed twice), so I gutted
it and rewrote the receive handler to use multiple chained descriptors.
Each RX descriptor gets a single 2K cluster, and the chip will fill in
as many as it needs to hold the complete packet.
User reports that this corrects the data corruption issues previously
observed and discussed on -current.
Note that this driver still needs to be hit with the busdma stick.
I intend to inflict said beating in the near future.
MFC after: 1 week
ad6c618bc7