Book Image

Mastering Embedded Linux Programming

By : Chris Simmonds
Book Image

Mastering Embedded Linux Programming

By: Chris Simmonds

Overview of this book

Mastering Embedded Linux Programming takes you through the product cycle and gives you an in-depth description of the components and options that are available at each stage. You will begin by learning about toolchains, bootloaders, the Linux kernel, and how to configure a root filesystem to create a basic working device. You will then learn how to use the two most commonly used build systems, Buildroot and Yocto, to speed up and simplify the development process. Building on this solid base, the next section considers how to make best use of raw NAND/NOR flash memory and managed flash eMMC chips, including mechanisms for increasing the lifetime of the devices and to perform reliable in-field updates. Next, you need to consider what techniques are best suited to writing applications for your device. We will then see how functions are split between processes and the usage of POSIX threads, which have a big impact on the responsiveness and performance of the final device The closing sections look at the techniques available to developers for profiling and tracing applications and kernel code using perf and ftrace.
Table of Contents (22 chapters)
Mastering Embedded Linux Programming
Credits
Foreword
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

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 BusyBox init as the default. The Yocto Project allows you to choose between System V init and systemd, with System V init the default.

The following table gives some metrics to compare the three:

 

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 system.

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