KaliPI custom build: how-to cross-compile ARM (Rpi2) on a Kali 2.0 host VM or PC, and gain 256MB RAM on your Rpi2

When I started to build my custom Kali ARM image for the Raspberry PI 2, I spent a lot of time looking for info and failing lengthy builds. So I kept these notes as an exercise to understand the process and speed up further builds.

I like cut-paste recipes for my experiments. By executing every step manually I gain better knowledge and control over what I'm doing, so I can manage over time the evolution of my needs, computing environment, external tools.
Only if and when it will be worthwhile, I will eventually automate the process with a script, however most of the time cut-paste is enough.

The updated version of the how-to and related files are on github: https://github.com/cybersec2k/kalipi-kernel