Book Image

Mastering Embedded Linux Programming - Third Edition

By : Frank Vasquez, Chris Simmonds
5 (3)
Book Image

Mastering Embedded Linux Programming - Third Edition

5 (3)
By: Frank Vasquez, Chris Simmonds

Overview of this book

If you’re looking for a book that will demystify embedded Linux, then you’ve come to the right place. Mastering Embedded Linux Programming is a fully comprehensive guide that can serve both as means to learn new things or as a handy reference. The first few chapters of this book will break down the fundamental elements that underpin all embedded Linux projects: the toolchain, the bootloader, the kernel, and the root filesystem. After that, you will learn how to create each of these elements from scratch and automate the process using Buildroot and the Yocto Project. As you progress, the book will show you how to implement an effective storage strategy for flash memory chips and install updates to a device remotely once it’s deployed. You’ll also learn about the key aspects of writing code for embedded Linux, such as how to access hardware from apps, the implications of writing multi-threaded code, and techniques to manage memory in an efficient way. The final chapters demonstrate how to debug your code, whether it resides in apps or in the Linux kernel itself. You’ll also cover the different tracers and profilers that are available for Linux so that you can quickly pinpoint any performance bottlenecks in your system. By the end of this Linux book, you’ll be able to create efficient and secure embedded devices using Linux.
Table of Contents (27 chapters)
1
Section 1: Elements of Embedded Linux
10
Section 2: System Architecture and Design Decisions
18
Section 3: Writing Embedded Applications
22
Section 4: Debugging and Optimizing Performance

Chapter 14: Starting with BusyBox runit

In the previous chapter, we looked at the classic System V init and state-of-the-art systemd programs. We also touched on BusyBox's minimal init program. Now, it is time to look at BusyBox's implementation of the runit program. BusyBox runit strikes a sensible balance between the simplicity of System V init and the flexibility of systemd. For this reason, the full version of runit is used in popular modern Linux distributions like Void. While systemd may dominate the cloud, it is usually overkill
for many embedded Linux systems. BusyBox runit offers advanced features such as service supervision and dedicated service logging without the complexity and overhead
of systemd.

In this chapter, I will show you how to divide your system up into separate BusyBox runit services, each with its own directory and run script. Next, we will see how check scripts can be used to force some services to wait for other services to start. Then, we will...