Making new build:

1) Make sure you have everything you need:
http://source.android.com/source/initializing.html
2a) At root repo catalogue (for system image):
$ . build/envsetup.sh
$ choosecombo 1 1 full_swift 2
$ make -j2

2b) At root repo catalogue (for kernel):
$ . build/envsetup.sh
$ choosecombo 1 1 generic 1
$ cd kernel
$ make -j2 ARCH=arm CROSS_COMPILE=arm-eabi-

3) And waste your time ...