1. Downloading kernel source
2. tar xvf source.tar.bz2
3. downloading arm cross compilation tool.
4. tar xvf arm-2010q1-202-arm-none-linux-gnueabi-i686-pc-linux-gnu.tar.bz2
5. setting up path for cross tool export PATH=$PATH:/home/shan/<cross tool folder>/bin/
6. after entering linux source dir make ARCH=arm versatile_defconfig (is this reliable   with raspberry pi)
7. make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi-
8. zImage is generated in /arch/arm/boot

git clone --depth 1 git://github.com/raspberrypi/linux.git

cp arch/arm/configs/bcmrpi_defconfig .config

make ARCH=arm CROSS_COMPILE=/usr/bin/arm-linux-gnueabi- oldconfig

make ARCH=arm CROSS_COMPILE=/usr/bin/arm-linux-gnueabi-

make ARCH=arm modules_install INSTALL_MOD_PATH=/tmp/modules