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

Types of update mechanism

In this section, I will describe three approaches to applying software updates: symmetric, or A/B, image update; asymmetric image update, also known as recovery mode update; and finally, atomic file update.

Symmetric image update

In this scheme, there are two copies of the operating system, each comprising the Linux kernel, root filesystem, and system applications. They are labeled as A and B in the following diagram:

Figure 10.2 – symmetric image update

Figure 10.2 – symmetric image update

Symmetric image updates work as follows:

  1. The bootloader has a flag that indicates which image it should load. Initially, the flag is set to A, so the bootloader loads OS image A.
  2. To install an update, the updater application, which is part of the operating system, overwrites OS image B.
  3. When complete, the updater changes the boot flag to B and reboots.
  4. Now the bootloader will load the new operating system.
  5. When a further update is installed...