The atu driver crashes on current (kernel + userland snapshot from a few
days ago). I also tried on a 2.1 userland with a current kernel and had the
same results. This problem is easy to reproduce, just plug the device and
ifconfig it. See details below :

atu0 at uhub1 port 1 configuration 1 interface 0
atu0: Atmel BW002 Wireless adapter, rev 1.10/1.00, addr 2
atu0: reattaching after firmware upload
atu0: at uhub1 port 1 (addr 2) disconnected
atu0 detached
atu0 at uhub1 port 1 configuration 1 interface 0
atu0: Atmel BW002 Wireless adapter, rev 1.10/1.00, addr 2
atu0: MAC address 00:00:1c:0b:d8:b5

# ifconfig atu0 inet 10.0.0.1
uvm_fault(0xc0862900, 0xc13cb000, 0, 1) -> 0xe
kernel: supervisor trap page fault, code = 0
Stopped in pid 527.1 (ifconfig) at netbsd:atu_initial_config+0xc0: movzbl
0x990(%ebx,%eax,1),%eax

db> bt
atu_initial_config
atu_init
ether_ioctl
iee80211_ioctl
atu_ioctl
in_infinit
in_control
compat_ifioctl
ifioctl
sys_ioctl
syscall_plain
--- syscall (number 54) ---