Building Embedded Linux Systems, 2nd Edition

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Definitions 2
Real Life and Embedded Linux Systems 5
Design and Implementation Methodology 27
2. Basic Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Types of Hosts 33
Types of Host/Target Development Setups 39
Types of Host/Target Debug Setups 41
Generic Architecture of an Embedded Linux System 43
System Startup 47
Types of Boot Configurations 48
System Memory Layout 51
3. Hardware Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Processor Architectures 56
Buses and Interfaces 64
I/O 72
Storage 79
General-Purpose Networking 81
Industrial-Grade Networking 83
System Monitoring 85
4. Development Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
A Practical Project Workspace 89
GNU Cross-Platform Development Toolchain 91
C Library Alternatives 115
Java 129
Perl 131
Python 134

Other Programming Languages 135
Eclipse: An Integrated Development Environment 135
Terminal Emulators 147
5. Kernel Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Selecting a Kernel 156
Configuring the Kernel 161
Compiling the Kernel 165
Installing the Kernel 167
In the Field 169
6. Root Filesystem Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
Basic Root Filesystem Structure 173
Libraries 177
Kernel Modules 183
Kernel Images 183
Device Files 184
Main System Applications 193
Custom Applications 201
System Initialization 201
7. Storage Device Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
MTD-Supported Devices 209
Disk Devices 231
To Swap or Not To Swap 234
8. Root Filesystem Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Filesystem Types for Embedded Devices 235
Writing a Filesystem Image to Flash Using an NFS-Mounted Root Filesystem
254
Placing a Disk Filesystem on a RAM Disk 254
Rootfs and Initramfs 255
Choosing a Filesystem’s Type and Layout 258
Handling Software Upgrades 261
9. Setting Up the Bootloader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Embedded Bootloaders 274
Server Setup for Network Boot 278
Using the U-Boot Bootloader 285
10. Setting Up Networking Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
Network Settings 302