The metadata used by BitBake can be classified into three major areas:

The configuration files define the global content, which is used to provide information and configure how the recipes will work. One common example of the configuration file is the machine file that has a list of settings, which describes the board hardware.

The classes are used by the whole system and can be inherited by recipes, according to their needs or by default, as in this case with classes used to define the system behavior and provide the base methods. For example, kernel.bbclass helps the process of build, install, and package of the Linux kernel, independent of version and vendor.

The classes and recipes describe the tasks to be run and provide the needed information to allow BitBake to generate the needed task chain...