Yocto Reference Manual

2

Yocto Reference Manual

1.3 Vocabulary

1.3.1 Recipes

Recipes contain information about the software project (author, homepage and license). A recipe is versioned, defines dependencies, contains the URL of the source code, describes how to fetch, configure and compile the sources. It describes how to package the software, e.g. into different .deb packages, which then contain the installation path. Recipes are basically written in Bitbake's own programming language, which has a simple syntax. However, a recipe can contain Python as well as bash code.

1.3.2 Classes

Classes combine functionality used inside recipes into reusable blocks.

1.3.3 Layers

A layer is a collection of recipes, classes and configuration metadata. A layer can depend on other layers and can be included or excluded one by one. It encapsulates a specific functionality and fulfills a specific purpose. Each layer falls into a specific category:

• Base

• Machine (BSP)

• Software

• Distribution

• Miscellaneous

Yocto's versioning scheme is reflected in every layer as version branches. For each Yocto

version, every layer has a named branch in its Git repository. You can add one or many layers of each category in your build.

A collection of OpenEmbedded layers can be found here, the search function is very helpful to see if a software package can be retrieved and integrated easily.

http://layers.openembedded.org/layerindex/branch/master/layers/

1.3.4 Machine

Machines are configuration variables, which describe the aspects of the target hardware.

1.3.5 Distro

A distribution describes the software configuration and comes with a set of software features.

© PHYTEC Messtechnik GmbH 2015 L-813e_2