mdev.conf写的不对。
加入下面的就可以：
# Move input devices to input directoryevent.* 0:0 0660 @(mkdir -p input&&mv $MDEV input)mice 0:0 0660 @(mkdir -p input&&mv $MDEV input)mouse.* 0:0 0660 @(mkdir -p input&&mv $MDEV input)
# Move input devices to input directory
event.* 0:0 0660 @(mkdir -p input&&mv $MDEV input)
mice 0:0 0660 @(mkdir -p input&&mv $MDEV input)
mouse.* 0:0 0660 @(mkdir -p input&&mv $MDEV input)
http://code.google.com/p/buildroot/source/browse/branches/john-avr32-buildroot/target/device/Atmel/atngw100-expanded/target_skeleton/etc/mdev.conf?r=766