$ cat /boot/loader.conf
zfs_load="YES"
vfs.root.mountfrom="zfs:zdisk"
vfs.root.mountfrom.options="rw"
vfs.zfs.prefetch_disable=0
if_bwn_load="YES"
bwn_v4_lp_ucode_load="YES"
wlan_ccmp_load="YES"
wlan_tkip_load="YES"
$ cat /etc/rc.conf
zfs_enable="YES"
hostname="roadgo.tong.com"
dbus_enable="YES"
hald_enable="YES"
wlans_bwn0="wlan0"
ifconfig_wlan0=" WPA DHCP ssid mytiantang channel 6 mode 11b "
$ pciconf -lv
siba_bwn0@pci0:4:0:0:class=0x028000 card=0x04b514e4 chip=0x431514e4 rev=0x01 hdr=0x00
vendor = 'Broadcom Corporation'
device = 'BCM4312 802.11b/g LP-PHY'
class = network
主要是将11g降为11b,但仍然有错误提示，不影响使用。