Being able to communicate on the serial interface of the arduino with an unprivileged user.

LESS extends CSS with dynamic behavior such as variables, mixins, operations and functions.
LESS runs on both the server-side (with Node.js and Rhino) or client-side (modern browsers only).

A guide describing how linux kernel work

There is really black magic !
also see that: http://www.agner.org/optimize/microarchitecture.pdf