Get Linux sources

Fetch linux source code:

$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

list the available release tags with

$ git tag -l 'v3.*'

list the available release tags with

$ git checkout <the-desired-tag>.

Compile

Assuming your cross compiler is called e.g. arm-linux-gnueabihf-gcc, you can compile by doing:

$ cd linux

$ export ARCH=arm

$ export CROSS_COMPILE=arm-linux-gnueabihf-

$ make imx_v6_v7_defconfig

$ make

$ make uImage

This should create a number of files, including arch/arm/boot/uImage and arch/arm/boot/dts/imx6q-sabresd.dtb.

(refs the rest on the site)