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For more information, please contact: U.S. Corporate and Government Sales (800) 382-3419 [email protected] For sales outside the United States, please contact: International Sales [email protected] Visit us on the Web: informit.com/aw Library of Congress Cataloging-in-Publication Data: Hallinan, Christopher. Embedded Linux primer : a practical real-world approach / Christopher Hallinan. p. cm. ISBN 978-0-13-701783-6 (hardback : alk. paper) 1. Linux. 2. Operating systems (Computers) 3. Embedded computer systems--Programming. I. Title. QA76.76.O63H34462 2011 005.4’32--dc22 2010032891 Copyright © 2011 Pearson Education, Inc. All rights reserved. Printed in the United States of America. This publication is protected by copyright, and permission must be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to: Pearson Education, Inc. Rights and Contracts Department 501 Boylston Street, Suite 900 Boston, MA 02116 Fax (617) 671-3447 ISBN-13: 978-0-137-01783-6 ISBN-10: 0-137-01783-9 Text printed in the United States on recycled paper at Courier in Westford, Massachusetts. First printing September 2010 Editor-in-Chief: Mark L. Taub Executive Acquisitions Editor: Debra Williams Cauley Development Editor: Michael Thurston Managing Editor: Kristy Hart Project Editors: Alexandra Maurer and Jovana San Nicolas-Shirley Copy Editor: Gayle Johnson Indexer: Heather McNeill Proofreader: Sarah Kearns Technical Reviewers: Robert P.J. Day, Kurt Lloyd, Jon Masters, Sandra Terrace, and Mark A. Yoder Publishing Coordinator: Kim Boedigheimer Cover Designer: Alan Clements Compositor: Tricia Bronkella Contents Foreword for the First Edition .......................................................................................xxv Foreword for the Second Edition ..................................................................................xxvi Preface .........................................................................................................................xxvii Acknowledgments for the First Edition ......................................................................xxxiii Acknowledgments for the Second Edition ...................................................................xxxv About the Author .......................................................................................................xxxvi Chapter 1 Introduction............................................................................................1 1.1 Why Linux? .............................................................................................................2 1.2 Embedded Linux Today ..........................................................................................3 1.3 Open Source and the GPL ...................................................................................... 3 1.3.1 Free Versus Freedom ........................................................................................4 1.4 Standards and Relevant Bodies ................................................................................5 1.4.1 Linux Standard Base ........................................................................................ 5 1.4.2 Linux Foundation ............................................................................................6 1.4.3 Carrier-Grade Linux ........................................................................................6 1.4.4 Mobile Linux Initiative: Moblin....................................................................... 7 1.4.5 Service Availability Forum................................................................................ 7 1.5 Summary .................................................................................................................8 1.5.1 Suggestions for Additional Reading ..................................................................8 vii viii Embedded Linux Primer, Second Edition Chapter 2 The Big Picture .......................................................................................9 2.1 Embedded or Not? ................................................................................................10 2.1.1 BIOS Versus Bootloader ................................................................................11 2.2 Anatomy of an Embedded System .........................................................................12 2.2.1 Typical Embedded Linux Setup ..................................................................... 13 2.2.2 Starting the Target Board ............................................................................... 14 2.2.3 Booting the Kernel .........................................................................................16 2.2.4 Kernel Initialization: Overview ...................................................................... 18 2.2.5 First User Space Process: init ....................................................................... 19 2.3 Storage Considerations ..........................................................................................20 2.3.1 Flash Memory ................................................................................................20 2.3.2 NAND Flash .................................................................................................22 2.3.3 Flash Usage ....................................................................................................23 2.3.4 Flash File Systems .......................................................................................... 24 2.3.5 Memory Space ...............................................................................................25 2.3.6 Execution Contexts ........................................................................................26 2.3.7 Process Virtual Memory .................................................................................28 2.3.8 Cross-Development Environment ..................................................................30 2.4 Embedded Linux Distributions .............................................................................32 2.4.1 Commercial Linux Distributions ................................................................... 33 2.4.2 Do-It-Yourself Linux Distributions ................................................................33 2.5 Summary ...............................................................................................................34 2.5.1 Suggestions for Additional Reading ................................................................35 Chapter 3 Processor Basics ....................................................................................37 3.1 Stand-Alone Processors ..........................................................................................38 3.1.1 IBM 970FX ...................................................................................................39 3.1.2 Intel Pentium M ............................................................................................ 39 Contents ix 3.1.3 Intel Atom™ .................................................................................................40 3.1.4 Freescale MPC7448 .......................................................................................40 3.1.5 Companion Chipsets .....................................................................................41 3.2 Integrated Processors: Systems on Chip .................................................................43 3.2.1 Power Architecture .........................................................................................44 3.2.2 Freescale Power Architecture .......................................................................... 44 3.2.3 Freescale PowerQUICC I ...............................................................................45 3.2.4 Freescale PowerQUICC II ............................................................................. 46 3.2.5 PowerQUICC II Pro ......................................................................................47 3.2.6 Freescale PowerQUICC III ............................................................................48 3.2.7 Freescale QorIQ™ ........................................................................................48 3.2.8 AMCC Power Architecture ............................................................................50 3.2.9 MIPS .............................................................................................................53