9780131679849

This book brings together indispensable knowledge for building efficient, high-value, Linux-based embedded products: information that has never been assembled in one place before. Drawing on years of experience as an embedded Linux consultant and field application engineer, Christopher Hallinan offers solutions for the specific technical issues you're most likely to face, demonstrates how to build an effective embedded Linux environment, and shows how to use it as productively as possible.

Christopher Hallinan is currently field applications engineer for Monta Vista Software, living and working in Massachusetts. Chris has spent more than 25 years in the networking and communications marketplace mostly in various product development roles, where he developed a strong background in the space where hardware meets software. Prior to joining Monta Vista, Chris spent four years as an independent Linux consultant providing custom Linux board ports, device drivers, and bootloaders. Chris’s introduction to the open source community was through contributions to the popular U-Boot bootloader. When not messing about with Linux, he is often found singing and playing a Taylor or Martin.

Foreword

xix

Preface

xxi

Acknowledgments

xxvii

About the Author

xxix

Introduction

1

(8)

Why Linux?

2

(1)

Embedded Linux Today

3

(1)

Open Source and the GPL

3

(2)

Free Versus Freedom

4

(1)

Standards and Relevant Bodies

5

(2)

Linux Standard Base

5

(1)

Open Source Development Labs

5

(2)

Chapter Summary

7

(2)

Suggestions for Additional Reading

7

(2)

Your First Embedded Experience

9

(28)

Embedded or Not?

10

(2)

BIOS Versus Bootloader

11

(1)

Anatomy of an Embedded System

12

(7)

Typical Embedded Linux Setup

14

(1)

Starting the Target Board

15

(1)

Booting the Kernel

16

(1)

Kernel Initialization: Overview

17

(2)

First User Space Process: init

19

(1)

Storage Considerations

19

(13)

Flash Memory

20

(2)

Nand Flash

22

(1)

Flash Usage

23

(1)

Flash File Systems

24

(1)

Memory Space

25

(1)

Execution Contexts

26

(2)

Process Virtual Memory

28

(2)

Cross-Development Environment

30

(2)

Embedded Linux Distributions

32

(2)

Commercial Linux Distributions

33

(1)

Do-It-Yourself Linux Distributions

34

(1)

Chapter Summary

34

(3)

Suggestions for Additional Reading

35

(2)

Processor Basics

37

(28)

Stand-alone Processors

38

(5)

IBM 970FX

39

(1)

Intel Pentium M

39

(1)

Freescale MPC7448

40

(1)

Companion Chipsets

41

(2)

Integrated Processors: Systems on Chip

43

(18)

PowerPC

44

(1)

AMCC PowerPC

44

(3)

Freescale PowerPC

47

(5)

MIPS

52

(1)

Broadcom MIPS

53

(2)

AMD MIPS

55

(1)

Other MIPS

56

(1)

ARM

56

(1)

TIARM

56

(2)

Freescale ARM

58

(1)

Intel ARM XScale

59

(1)

Other ARM

60

(1)

Other Architectures

60

(1)

Hardware Platforms

61

(1)

CompactPCI

61

(1)

ATCA

61

(1)

Chapter Summary

62

(3)

Suggestions For Additional Reading

63

(2)

The Linux Kernel--A Different Perspective

65

(34)

Background

66

(4)

Kernel Versions

67

(2)

Kernel Source Repositories

69

(1)

Linux Kernel Construction

70

(9)

Top-Level Source Directory

70

(1)

Compiling the Kernel

71

(2)

The Kernel Proper: vmlinux

73

(2)

Kernel Image Components

75

(4)

Subdirectory Layout

79

(1)

Kernel Build System

79

(17)

The Dot-Config

80

(2)

Configuration Editor(s)

82

(3)

Makefile Targets

85

(3)

Kernel Configuration

88

(2)

Custom Configuration Options

90

(4)

Kernel Makefiles

94

(1)

Kernel Documentation

95

(1)

Obtaining a Linux Kernel

96

(1)

What Else Do I Need?

96

(1)

Chapter Summary

97

(2)

Suggestions for Additional Reading

98

(1)

Kernel Initialization

99

(30)

Composite Kernel Image: Piggy and Friends

100

(9)

The Image Object

103

(1)

Architecture Objects

104

(1)

Bootstrap Loader

105

(1)

Boot Messages

106

(3)

Initialization Flow of Control

109

(5)

Kernel Entry Point: head.o

111

(2)

Kernel Startup: main.c

113

(1)

Architecture Setup

114

(1)

Kernel Command Line Processing

114

(7)

The___setup Macro

116

(5)

Subsystem Initialization

121

(2)

The* ___initcall Macros

122

(1)

The init Thread

123

(5)

Initialization via initcalls

125

(1)

Final Boot Steps

126

(2)

Chapter Summary

128

(1)

Suggestions for Additional Reading

128

(1)

System Initialization

129

(28)

Root File System

130

(6)

FHS: File System Hierarchy Standard

131

(1)

File System Layout

131

(1)

Minimal File System

132

(2)

The Root FS Challenge

134

(1)

Trial-and-Error Method

135

(1)

Automated File System Build Tools

135

(1)

Kernel's Last Boot Steps

136

(3)

First User Space Program

137

(1)

Resolving Dependencies

138

(1)

Customized Initial Process

138

(1)

The Init Process

139

(6)

inittab

142

(2)

Example Web Server Startup Script

144

(1)

Initial RAM Disk

145

(7)

Initial RAM Disk Purpose

146

(1)

Booting with initrd

146

(1)

Bootloader Support for initrd

147

(2)

initrd Magic: linuxrc

149

(1)

The initrd Plumbing

150

(1)

Building an initrd Image

151

(1)

Using initramfs

152

(1)

Shutdown

153

(1)

Chapter Summary

154

(3)

Suggestions for Additional Reading

155

(2)

Bootloaders

157

(32)

Role of a Bootloader

158

(1)

Bootloader Challenges

159

(5)

DRAM Controller

159

(1)

Flash Versus RAM

160

(1)

Image Complexity

160

(3)

Execution Context

163

(1)

A Universal Bootloader: Das U-Boot

164

(8)

System Configuration: U-Boot

164

(3)

U-Boot Command Sets

167

(1)

Network Operations

167

(3)

Storage Subsystems

170

(1)

Booting from Disk: U-Boot

171

(1)

Porting U-Boot

172

(11)

EP405 U-Boot Port

172

(2)

U-Boot Makefile Configuration Target

174

(1)

EP405 Processor Initialization

174

(3)

Board-Specific Initialization

177

(3)

Porting Summary

180

(1)

U-Boot Image Format

181

(2)

Other Bootloaders

183

(3)

Lilo

183

(1)

GRUB

184

(2)

Still More Bootloaders

186

(1)

Chapter Summary

186

(3)

Suggestions for Additional Reading

187

(2)

Device Driver Basics

189

(24)

Device Driver Concepts

190

(9)

Loadable Modules

191

(1)

Device Driver Architecture

192

(1)

Minimal Device Driver Example

192

(1)

Module Build Infrastructure

193

(4)

Installing Your Device Driver

197

(1)

Loading Your Module

198

(1)

Module Utilities

199

(6)

insmod

199

(1)

Module Parameters

199

(2)

Ismod

201

(1)

modprobe

201

(2)

depmod

203

(1)

rmmod

203

(1)

modinfo

204

(1)

Driver Methods

205

(4)

Driver File System Operations

205

(3)

Device Nodes and mknod

208

(1)

Bringing It All Together

209

(2)

Device Drivers and the GPL

211

(1)

Chapter Summary

211

(2)

Suggestions for Additional Reading

212

(1)

File Systems

213

(34)

Linux File System Concepts

214

(2)

Partitions

214

(2)

ext2

216

(5)

Mounting a File System

218

(1)

Checking File System Integrity

219

(2)

ext3

221

(3)

ReiserFS

224

(1)

JFFS2

225

(3)

cramfs

228

(2)

Network File System

230

(4)

Root File System on NFS

232

(2)

Pseudo File Systems

234

(6)

Proc File System

234

(4)

sysfs

238

(2)

Other File Systems

240

(2)

Building a Simple File System

242

(1)

Chapter Summary

243

(4)

Suggestions for Additional Reading

244

(3)

MTD Subsystem

247

(26)

Enabling MTD Services

248

(3)

Building MTD

250

(1)

MTD Basics

251

(2)

Configuring MTD

253

(1)

MTD Partitions

253

(12)

Redboot Partition Table Partitioning

255

(4)

Kernel Command Line Partitioning

259

(1)

Mapping Driver

260

(2)

Flash Chip Drivers

262

(1)

Board-Specific Initialization

263

(2)

MTD Utilities

265

(5)

JFFS2 Root File System

268

(2)

Chapter Summary

270

(3)

Suggestions for Additional Reading

271

(2)

BusyBox

273

(16)

Introduction to BusyBox

274

(1)

BusyBox is Easy

275

(1)

BusyBox Configuration

275

(3)

Cross-Compiling BusyBox

277

(1)

BusyBox Operation

278

(10)

BusyBox Init

281

(2)

Example rcS Initialization Script

283

(1)

BusyBox Target Installation

284

(2)

BusyBox Commands

286

(2)

Chapter Summary

288

(1)

Suggestions for Additional Reading

288

(1)

Embedded Development Environment

289

(20)

Cross-Development Environment

290

(5)

``Hello World''---Embedded

291

(4)

Host System Requirements

295

(1)

Hardware Debug Probe

296

(1)

Hosting Target Boards

296

(10)

TFTP Server

296

(2)

BOOTP/DHCP Server

298

(2)

NFS Server

300

(2)

Target NFS Root Mount

302

(2)

U-Boot NFS Root Mount Example

304

(2)

Chapter Summary

306

(3)

Suggestions for Additional Reading

307

(2)

Development Tools

309

(42)

GNU Debugger (GDB)

310

(7)

Debugging a Core Dump

311

(2)

Invoking GDB

313

(2)

Debug Session in GDB

315

(2)

Data Display Debugger

317

(2)

cbrowser/cscope

319

(2)

Tracing and Profiling Tools

321

(19)

strace

321

(4)

strace Variations

325

(2)

Itrace

327

(1)

ps

328

(2)

top

330

(2)

mtrace

332

(2)

dmalloc

334

(3)

Kernel Oops

337

(3)

Binary Utilities

340

(6)

readelf

340

(2)

Examining Debug Info Using readelf

342

(2)

objdump

344

(1)

objcopy

345

(1)

Miscellaneous Binary Utilities

346

(3)

strip

346

(1)

addr2line

346

(1)

strings

347

(1)

Idd

347

(1)

nm

348

(1)

prelink

349

(1)

Chapter Summary

349

(2)

Suggestions for Additional Reading

350

(1)

Kernel Debugging Techniques

351

(48)

Challenges to Kernel Debugging

352

(1)

Using KGDB for Kernel Debugging

353

(7)

KGDB Kernel Configuration

355

(1)

Target Boot with KGDB Support

355

(3)

Useful Kernel Breakpoints

358

(2)

Debugging the Linux Kernel

360

(25)

gdb Remote Serial Protocol

361

(3)

Debugging Optimized Kernel Code

364

(5)

gdb User-Defined Commands

369

(1)

Useful Kernel gdb Macros

370

(8)

Debugging Loadable Modules

378

(5)

printk Debugging

383

(1)

Magic SysReq Key

384

(1)

Hardware-Assisted Debugging

385

(7)

Programming Flash Using a JTAG Probe

387

(2)

Debugging with a JTAG Probe

389

(3)

When It Doesn't Boot

392

(5)

Early Serial Debug Output

393

(1)

Dumping the printk Log Buffer

394

(2)

KGDB on Panic

396

(1)

Chapter Summary

397

(2)

Suggestions for Additional Reading

398

(1)

Debugging Embedded Linux Applications

399

(22)

Target Debugging

400

(1)

Remote (Cross) Debugging

400

(5)

gdbserver

403

(2)

Debugging with Shared Libraries

405

(6)

Shared Library Events in GDB

407

(4)

Debugging Multiple Tasks

411

(6)

Debugging Multiple Processes

411

(3)

Debugging Multithreaded Applications

414

(3)

Debugging Bootloader/Flash Code

417

(1)

Additional Remote Debug Options

417

(2)

Debugging via Serial Port

418

(1)

Attaching to a Running Process

418

(1)

Chapter Summary

419

(2)

Suggestions for Additional Reading

419

(2)

Porting Linux

421

(24)

Linux Source Organization

422

(2)

The Architecture Branch

422

(2)

Custom Linux for Your Board

424

(7)

Prerequisites and Assumptions

426

(1)

Customizing Kernel Initialization

427

(2)

Static Kernel Command Line

429

(2)

Platform Initialization

431

(8)

Early Variable Access

435

(1)

Board Information Structure

436

(2)

Machine-Dependent Calls

438

(1)

Putting It All Together

439

(3)

Other Architectures

442

(1)

Chapter Summary

442

(3)

Suggestions for Additional Reading

443

(2)

Linux and Real Time

445

(24)

What Is Real Time?

446

(3)

Soft Real Time

446

(1)

Hard Real Time

446

(1)

Linux Scheduling

447

(1)

Latency

447

(2)

Kernel Preemption

449

(4)

Impediments to Preemption

449

(2)

Preemption Models

451

(1)

SMP Kernel

452

(1)

Sources of Preemption Latency

453

(1)

Real-Time Kernel Patch

453

(7)

Real-Time Features

455

(3)

O(1) Scheduler

458

(1)

Creating a Real-Time Process

458

(1)

Critical Section Management

459

(1)

Debugging the Real-Time Kernel

460

(7)

Soft Lockup Detection

460

(1)

Preemption Debugging

461

(1)

Debug Wakeup Timing

461

(1)

Wakeup Latency History

462

(1)

Interrupt Off Timing

462

(1)

Interrupt Off History

462

(2)

Latency Tracing

464

(2)

Debugging Deadlock Conditions

466

(1)

Runtime Control of Locking Mode

467

(1)

Chapter Summary

467

(2)

Suggestions for Additional Reading

467

(2)

Appendix A: GNU Public License

469

(10)

Appendix B: U-Boot Configurable Commands

479

(4)

Appendix C: BusyBox Commands

483

(8)

Appendix D: SDRAM Interface Considerations

491

(10)

SDRAM Basics

492

(2)

SDRAM Refresh

493

(1)

Clocking

494

(1)

SDRAM Setup

495

(5)

Summary

500

(1)

Suggestions for Additional Reading

500

(1)

Appendix E: Open Source Resources

501

(4)

Appendix F: Sample BDI-2000 Configuration File

505

(8)

Index

513

What is included with this book?

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Embedded Linux Primer : A Practical, Real-World Approach

Embedded Linux Primer : A Practical, Real-World Approach

0131679848

Summary

Author Biography

Table of Contents

Supplemental Materials

Excerpts