Introducing device trees
You are almost certainly going to encounter device trees at some point. This section aims to give you a quick overview of what they are and how they work but there are many details that are not discussed.
A device tree is a flexible way to define the hardware components of a computer system. Usually, the device tree is loaded by the bootloader and passed to the kernel, although it is possible to bundle the device tree with the kernel image itself to cater for bootloaders that are not capable of handling them separately.
The format is derived from a Sun Microsystems bootloader known as OpenBoot, which was formalized as the Open Firmware specification, IEEE standard IEEE1275-1994. It was used in PowerPC-based Macintosh computers ...