Mastering Embedded Linux Programming: Unleash the full potential of Embedded Linux with Linux 4.9 and Yocto Project 2.2 (Morty) Updates, 2nd Edition

468 Pages·2017·5.143 MB·English

by  Chris Simmonds

Mastering Embedded Linux Programming
Second Edition
Unleash the full potential of Embedded Linux
Chris Simmonds
BIRMINGHAM - MUMBAI
Mastering Embedded Linux Programming
Second Edition
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First published: December 2015
Second edition: June 2017
Production reference: 1280617
Published by Packt Publishing Ltd.
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ISBN 978-1-78728-328-2
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Credits
Author Copy Editors
Chris Simmonds Madhusudan Uchil
Stuti Shrivastava
Reviewers Project Coordinator
Daiane Angolini Virginia Dias
Otavio Salvador
Alex Tereschenko
Commissioning Editor Proofreader
Kartikey Pandey Safis Editing
Acquisition Editor Indexer
Prateek Bharadwaj Rekha Nair
Content Development Editor Graphics
Sharon Raj Kirk D'Penha
Technical Editor Production Coordinator
Vishal Kamal Mewada Melwyn Dsa
About the Author
Chris Simmonds is a software consultant and trainer living in southern England. He has
almost two decades of experience in designing and building open-source embedded
systems. He is the founder and chief consultant at 2net Ltd, which provides professional
training and mentoring services in embedded Linux, Linux device drivers, and Android
platform development. He has trained engineers at many of the biggest companies in the
embedded world, including ARM, Qualcomm, Intel, Ericsson, and General Dynamics. He is
a frequent presenter at open source and embedded conferences, including the Embedded
Linux Conference and Embedded World. You can see some of his work on the Inner
Penguin blog at www.2net.co.uk.
I would like to thank Shirley Simmonds for being so supportive during the long hours that
I was shut in my home office researching and writing this book. I would also like to thank
all the people who have helped me with the research of the technical aspects of this book,
whether they realized that is what they were doing or not. In particular, I would like to
mention Klaas van Gend, Thomas Petazzoni, and Ralph Nguyen for their help and advice.
Lastly, I would like to thank Sharon Raj, Vishal Mewada, and the team at Packt Publishing
for keeping me on track and bringing the book to fruition.
About the Reviewers
Daiane Angolini has been working with embedded Linux since 2008. She has been working
as an application engineer at NXP, acting on internal development, porting custom
applications from Android, and on-customer support for i.MX architectures in areas such as
Linux kernel, u-boot, Android, Yocto Project, and user-space applications. However, it was
on the Yocto Project that she found her place. She has coauthored the books Embedded Linux
Development with Yocto Project and Heading for the Yocto Project, and learned a lot in the
process.
Otavio Salvador loves technology and started his free software activities in 1999. In 2002, he
founded O.S. Systems, a company focused on embedded system development services and
consultancy worldwide, creating and maintaining customized BSPs, and helping companies
with their product's development challenges. This resulted in him joining the
OpenEmbedded community in 2008, when he became an active contributor to the
OpenEmbedded project. He has coauthored the books Embedded Linux Development with
Yocto Project and Heading for the Yocto Project.
Alex Tereschenko is an embedded systems engineer by day, and an avid maker by night,
who is convinced that computers can do a lot of good for people when they are interfaced
with real-world objects, as opposed to just crunching data in a dusty corner. That's what's
driving him in his projects, and this is why embedded systems and the Internet of Things
are the topics he enjoys the most.
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Table of Contents
Preface
1
Chapter 1: Starting Out
8
Selecting the right operating system 9
The players 10
Project life cycle 12
The four elements of embedded Linux 12
Open source 13
Licenses 13
Hardware for embedded Linux 15
Hardware used in this book 16
The BeagleBone Black 16
QEMU 17
Software used in this book 18
Summary 19
Chapter 2: Learning About Toolchains
20
Introducing toolchains 21
Types of toolchains 22
CPU architectures 23
Choosing the C library 25
Finding a toolchain 26
Building a toolchain using crosstool-NG 28
Installing crosstool-NG 28
Building a toolchain for BeagleBone Black 28
Building a toolchain for QEMU 30
Anatomy of a toolchain 31
Finding out about your cross compiler 31
The sysroot, library, and header files 34
Other tools in the toolchain 34
Looking at the components of the C library 35
Linking with libraries – static and dynamic linking 36
Static libraries 37
Shared libraries 38
Understanding shared library version numbers 39
The art of cross compiling 40
Simple makefiles 40
Autotools 41
An example: SQLite 43
Package configuration 44
Problems with cross compiling 45
Summary 46
Chapter 3: All About Bootloaders
47
What does a bootloader do? 48
The boot sequence 48
Phase 1 – ROM code 49
Phase 2 – secondary program loader 50
Phase 3 – TPL 51
Booting with UEFI firmware 52
Moving from bootloader to kernel 53
Introducing device trees 54
Device tree basics 55
The reg property 56
Labels and interrupts 57
Device tree include files 58
Compiling a device tree 60
Choosing a bootloader 60
U-Boot 61
Building U-Boot 61
Installing U-Boot 63
Using U-Boot 65
Environment variables 66
Boot image format 66
Loading images 67
Booting Linux 69
Automating the boot with U-Boot scripts 69
Porting U-Boot to a new board 70
Board-specific files 71
Configuring header files 73
Building and testing 73
Falcon mode 75
Barebox 75
Getting barebox 75
Building barebox 76
Using barebox 77
Summary 78
[ ii ]