wifi interface on Beagle Board xm not detected


I am trying to run ubuntu 11.04 (kernel built from git) on Beagle board xm.

When i put any wifi usb dongle( like netgear, belkin). Driver gets loaded verified by lsusb command on Beagle Board xm.

But i am not able to see any interface like wlan0. (iwconfig - no interface available)

So please let me know what is solution above case so that i can able to see wifi interface (wlan0)?
(Can i do any module insertion or any changes in wifi interface file ?)

Chetan Bidap