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

Creating filesystem images with device tables

We saw earlier, in the Creating a boot initramfs section, that the kernel has an option to create initramfs using a device table. Device tables are really useful because they allow a non-root user to create device nodes and to allocate arbitrary UID and GID values to any file or directory. The same concept has been applied to tools that create other filesystem image formats, as shown in this mapping from filesystem format to tool:

  • jffs2: mkfs.jffs2
  • ubifs: mkfs:ubifs
  • ext2: genext2fs

We will look at jffs2 and ubifs in Chapter 9, Creating a Storage Strategy, when we look at filesystems for flash memory. The third, ext2, is a format commonly used for managed flash memory including SD cards. The example that follows uses ext2 to create a disk image that can be copied to an SD card.

To begin with, you need to install the genext2fs tool on your host. On Ubuntu, the package to install is named genext2fs:

$ sudo apt...