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 15: Managing Power

For devices operating on battery power, power management is critical: anything we can do to reduce power usage will increase battery life. Even for devices running on mains power, reducing power usage has benefits in reducing the need for cooling and energy costs. In this chapter, I will introduce the four principles of power management:

  • Don't rush if you don't have to.
  • Don't be ashamed of being idle.
  • Turn off things you are not using.
  • Sleep when there is nothing else to do.

Putting these into more technical terms, the principles mean that the power management system should endeavor to reduce the CPU clock frequency. During idle periods, it should choose the deepest sleep state possible; it should reduce the load by powering down unused peripherals and it should be able to put the whole system into a suspended state while ensuring power state transitions are quick.

Linux has features that address each of these...