Linux Device Drivers, Second Edition

Audience of This Book

On the technical side, this text should offer a hands-on approach to understanding the kernel internals and some of the design choices made by the Linux developers. Although the main, official target of the book is teaching how to write device drivers, the material should give an interesting overview of the kernel implementation as well.

Although real hackers can find all the necessary information in the official kernel sources, usually a written text can be helpful in developing programming skills. The text you are approaching is the result of hours of patient grepping through the kernel sources, and we hope the final result is worth the effort it took.

This book should be an interesting source of information both for people who want to experiment with their computer and for technical programmers who face the need to deal with the inner levels of a Linux box. Note that “a Linux box” is a wider concept than “a PC running Linux,” as many platforms are supported by our operating system, and kernel programming is by no means bound to a specific platform. We hope this book will be useful as a starting point for people who want to become kernel hackers but don’t know where to start.

The Linux enthusiast should find in this book enough food for her mind to start playing with the code base and should be able to join the group of developers that is continuously working on new capabilities and performance enhancements. This book does not cover the Linux kernel in its entirety, of course, but Linux device driver authors need to know how to work with many of the kernel’s subsystems. It thus makes a good introduction to kernel programming in general. Linux is still a work in progress, and there’s always a place for new programmers to jump into the game.

If, on the other hand, you are just trying to write a device driver for your own device, and you don’t want to muck with the kernel internals, the text should be modularized enough to fit your needs as well. If you don’t want to go deep into the details, you can just skip the most technical sections and stick to the standard API used by device drivers to seamlessly integrate with the rest of the kernel.

The main target of this book is writing kernel modules for version 2.4 of the Linux kernel. A module is object code that can be loaded at runtime to add new functionality to a running kernel. Wherever possible, however, our sample code also runs on versions 2.2 and 2.0 of the kernel, and we point out where things have changed along the way.