Copyleft is a legal way to use copyright law in order to maximize rights and express freedom. It greatly impacts our day-to-day work to such a large extent that companies must know how to deal with open source and free software licenses, as they have a big impact on their products.

When building a Linux distribution, there are at least two projects being used: the Linux kernel and a compiler. The most commonly used compiler nowadays is the GNU Compiler Collection (GCC).

The Linux kernel is released under the GPLv2 license, and the GCC is released under the GPLv2, GPLv2.1, and GPLv3 licenses, depending on the project used.

However, a Linux-based system can include virtually all projects available throughout the world, in addition to all applications made by the company for its product. How do we know the number of projects and licenses that are included, and how do we fulfill copyleft compliance requirements?

In this chapter, we will look at how the Yocto Project can help us with the most common tasks required for copyleft compliance.