- always reinitialize the rx descriptors, even if the mbuf is kept.
This should fix the hangs on ifconfig that were observed
- on an rx overflow, reinitialize the descriptor so that the interface
will not hang
- correct some bus_dmamap_sync() calls
- correct some debug messages
- some minor nits
in most machines of the Sun Ultra series. This is a port of the NetBSD
driver which I enhanced to make use of the gather functionality and the
configurable RX buffer offset to avoid copying all received/sent packet
(instead, packets will be directly DMAd from mbuf chains and into mbuf
clusters now).