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

Moving from the bootloader to a kernel

When the bootloader passes control to the kernel, it has to pass some basic information, which includes the following:

  • The machine number, which is used on PowerPC and Arm platforms without support for a device tree, to identify the type of the SoC.
  • Basic details of the hardware that's been detected so far, including (at the very least) the size and location of the physical RAM and the CPU's clock speed.
  • The kernel command line.
  • Optionally, the location and size of a device tree binary.
  • Optionally, the location and size of an initial RAM disk, called the initial RAM file system (initramfs).

The kernel command line is a plain ASCII string that controls the behavior of Linux by giving, for example, the name of the device that contains the root filesystem. We will look at the details of this in the next chapter. It is common to provide the root filesystem as a RAM disk, in which case it is the responsibility...