Book Image

Mastering Embedded Linux Programming - Second Edition

By : Chris Simmonds
Book Image

Mastering Embedded Linux Programming - Second Edition

By: Chris Simmonds

Overview of this book

Embedded Linux runs many of the devices we use every day, from smart TVs to WiFi routers, test equipment to industrial controllers - all of them have Linux at their heart. Linux is a core technology in the implementation of the inter-connected world of the Internet of Things. The comprehensive guide shows you the technologies and techniques required to build Linux into embedded systems. You will begin by learning about the fundamental elements that underpin all embedded Linux projects: the toolchain, the bootloader, the kernel, and the root filesystem. You’ll see how to create each of these elements from scratch, and how to automate the process using Buildroot and the Yocto Project. Moving on, you’ll find out how to implement an effective storage strategy for flash memory chips, and how to install updates to the device remotely once it is deployed. You’ll also get to know the key aspects of writing code for embedded Linux, such as how to access hardware from applications, the implications of writing multi-threaded code, and techniques to manage memory in an efficient way. The final chapters show you how to debug your code, both in applications and in the Linux kernel, and how to profile the system so that you can look out for performance bottlenecks. By the end of the book, you will have a complete overview of the steps required to create a successful embedded Linux system.
Table of Contents (17 chapters)

Introducing the init programs

The three init programs that you are most likely to encounter in embedded devices are BusyBox init, System V init, and systemd. Buildroot has options to build all three with the init BusyBox as the default. The Yocto Project allows you to choose between the System V called init and systemd with System V init as the default.

The following table gives some metrics to compare the three:

Metric

BusyBox init

System V init

systemd

Complexity

Low

Medium

High

Boot-up speed

Fast

Slow

Medium

Required shell

ash

ash or bash

None

Number of executables

0

4

50(*)

libc

Any

Any

glibc

Size (MiB)

0

0.1

34(*)

(*) Based on the Buildroot configuration of systemd.

Broadly speaking, there is an increase in flexibility and complexity as you go from BusyBox init to systemd.

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