Book Image

Linux: Embedded Development

By : Alexandru Vaduva, Alex Gonzalez, Chris Simmonds
Book Image

Linux: Embedded Development

By: Alexandru Vaduva, Alex Gonzalez, Chris Simmonds

Overview of this book

Embedded Linux is a complete Linux distribution employed to operate embedded devices such as smartphones, tablets, PDAs, set-top boxes, and many more. An example of an embedded Linux distribution is Android, developed by Google. This learning path starts with the module Learning Embedded Linux Using the Yocto Project. It introduces embedded Linux software and hardware architecture and presents information about the bootloader. You will go through Linux kernel features and source code and get an overview of the Yocto Project components available. The next module Embedded Linux Projects Using Yocto Project Cookbook takes you through the installation of a professional embedded Yocto setup, then advises you on best practices. Finally, it explains how to quickly get hands-on with the Freescale ARM ecosystem and community layer using the affordable and open source Wandboard embedded board. Moving ahead, the final module Mastering Embedded Linux Programming takes you through the product cycle and gives you an in-depth description of the components and options that are available at each stage. You will see how functions are split between processes and the usage of POSIX threads. By the end of this learning path, your capabilities will be enhanced to create robust and versatile embedded projects. This Learning Path combines some of the best that Packt has to offer in one complete, curated package. It includes content from the following Packt products: ? Learning Embedded Linux Using the Yocto Project by Alexandru Vaduva ? Embedded Linux Projects Using Yocto Project Cookbook by Alex González ? Mastering Embedded Linux Programming by Chris Simmonds
Table of Contents (6 chapters)

I looked at how the kernel boots up to the point that it launches the first program, init, in Chapter 4, Porting and Configuring the Kernel and in Chapter 5, Building a Root Filesystem and Chapter 6, Selecting a Build System, I looked at creating root filesystems of varying complexity, all of which contained an init program. Now it is time to look at the init program in more detail and discover why it is so important to the rest of the system.

There are many possible implementations of init. I will describe the three main ones in this chapter: BusyBox init, System V init, and systemd. For each one, I will give an overview of how it works and the types of system it suits best. Part of that is balancing the trade-off between complexity and flexibility.

We saw in Chapter 4, Porting and Configuring the Kernel, how the kernel bootstrap code seeks to find a root filesystem, either initramfs or a filesystem specified...