Embedded Linux Systems with the Yocto Project

Foreword xv

Preface xvii

Acknowledgments xxi

About the Author xxiii



Chapter 1: Linux for Embedded Systems 1

1.1 Why Linux for Embedded Systems? 1

1.2 Embedded Linux Landscape 3

1.3 A Custom Linux Distribution-Why Is It Hard? 8

1.4 A Word about Open Source Licensing 9

1.5 Organizations, Relevant Bodies, and Standards 11

1.6 Summary 13

1.7 References 14



Chapter 2: The Yocto Project 15

2.1 Jumpstarting Your First Yocto Project Build 15

2.2 The Yocto Project Family 26

2.3 A Little Bit of History 28

2.4 Yocto Project Terms 31

2.5 Summary 33

2.6 References 34



Chapter 3: OpenEmbedded Build System 35

3.1 Building Open Source Software Packages 35

3.2 OpenEmbedded Workflow 39

3.3 OpenEmbedded Build System Architecture 45

3.4 Summary 56

3.5 References 57



Chapter 4: BitBake Build Engine 59

4.1 Obtaining and Installing BitBake 59

4.2 Running BitBake 61

4.3 BitBake Metadata 70

4.4 Metadata Syntax 71

4.5 Source Download 86

4.6 HelloWorld-BitBake Style 95

4.7 Dependency Handling 99

4.8 Version Selection 102

4.9 Variants 103

4.10 Default Metadata 103

4.11 Summary 107

4.12 References 108



Chapter 5: Troubleshooting 109

5.1 Logging 110

5.2 Task Execution 116

5.3 Analyzing Metadata 119

5.4 Development Shell 120

5.5 Dependency Graphs 121

5.6 Debugging Layers 122

5.7 Summary 124



Chapter 6: Linux System Architecture 127

6.1 Linux or GNU/Linux? 127

6.2 Anatomy of a Linux System 128

6.3 Bootloader 129

6.4 Kernel 134

6.5 User Space 141

6.6 Summary 143

6.7 References 144



Chapter 7: Building a Custom Linux Distribution 145

7.1 Core Images-Linux Distribution Blueprints 146

7.2 Building Images from Scratch 160

7.3 Image Options 161

7.4 Distribution Configuration 169

7.5 External Layers 181

7.6 Hob 181

7.7 Summary 184



Chapter 8: Software Package Recipes 185

8.1 Recipe Layout and Conventions 185

8.2 Writing a New Recipe 196

8.3 Recipe Examples 212

8.4 Devtool 218

8.5 Summary 224

8.6 References 224



Chapter 9: Kernel Recipes 225

9.1 Kernel Configuration 226

9.2 Kernel Patches 231

9.3 Kernel Recipes 233

9.4 Out-of-Tree Modules 251

9.5 Device Tree 257

9.6 Summary 258

9.7 References 259



Chapter 10: Board Support Packages 261

10.1 Yocto Project BSP Philosophy 261

10.2 Building with a BSP 265

10.3 Inside a Yocto Project BSP 277

10.4 Creating a Yocto Project BSP 282

10.5 Tuning 289

10.6 Creating Bootable Media Images 290

10.7 Summary 299

10.8 References 299



Chapter 11: Application Development 301

11.1 Inside a Yocto Project ADT 302

11.2 Setting Up a Yocto Project ADT 304

11.3 Building Applications 315

11.4 Eclipse Integration 317

11.5 Application Development Using an Emulated Target 331

11.6 Summary 333

11.7 References 334



Chapter 12: Licensing and Compliance 335

12.1 Managing Licenses 335

12.2 Managing Source Code 341

12.3 Summary 343

12.4 References 344



Chapter 13: Advanced Topics 345

13.1 Toaster 345

13.2 Build History 358

13.3 Source Mirrors 366

13.4 Autobuilder 368

13.5 Summary 374

13.6 References 375



Appendix A: Open Source Licenses 377

A.1 MIT License (MIT) 377

A.2 GNU General Public License (GPL) Version 2 378

A.3 GNU General Public License (GPL) Version 3 384

A.4 Apache License Version 2.0 397



Appendix B: Metadata Reference 403





Index 429