Exploring metadata

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

• Configuration (the .conf files)
• Classes (the .bbclass files)
• Recipes (the .bb and .bbappend files)

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, which has a list of settings that describes the hardware.

The classes are used by the whole system and can be inherited by recipes according to their needs, or by default, and are used to define the system's behavior and provide the base methods. For example, kernel.bbclass helps to abstract common tasks related to building and packaging the Linux kernel independently of version or vendor changes.

Note

The recipes and classes are written in a mix of Python and shell scripting code.

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