Makefile in kernel root:

VERSION = 2
PATCHLEVEL = 6
SUBLEVEL = 24
EXTRAVERSION =
NAME = Arr Matey! A Hairy Bilge Rat!

ARCH=arm
CROSS_COMPILE=arm-none-linux-gnueabi-


last two lines are important. you can probably also just export them on commandline:

ARCH=arm
CROSS_COMPILE=arm-none-linux-gnueabi-

export ARCH CROSS_COMPILE