wifi on gentoo

This is the wireless HW I have:

gerbaudo@gerbaudo-hp ~ $ /usr/sbin/lspci -v | grep Wireless
10:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG Network Connection (rev 02)

First of all you need to enable the drivers in your .config
(or use the .config you have, or create it automagically).
These are the flags I have

#
# Wireless LAN
#
CONFIG_WLAN_80211=y
CONFIG_IWL3945=m
CONFIG_IWL3945_QOS=y
...
#
# Wireless
#
CONFIG_CFG80211=y
CONFIG_NL80211=y
CONFIG_WIRELESS_EXT=y
CONFIG_MAC80211=y

then build the kernel and try some debugging

ifconfig wlan0 up

then copy your old wpa_supplicant.conf and then

add in /etc/conf.d/net

config_wlan0=("dhcp")
modules=( "wpa_supplicant" )
mode_wlan0="managed"
wpa_supplicant_wlan0="-Dwext"


cd /etc/init.d ; ln -s net.lo net.wlan0


One further thing that I did (but I don't know whether
or not it's necessary) is :

wpa_supplicant -B -Dwext -iwlan0 -c/etc/wpa_supplicant/wpa_supplicant.conf

At the next reboot it tried eth0, timed-out, and connected on wlan0 :-)