这本经典书籍目前已更新至第三版,对于那些希望在Linux操作系统下支持计算机外围设备、运行新硬件,或者仅仅对Linux内核普通编程感兴趣的人来说,它是本必读书籍。《Linux设备驱动程序》揭示了如何给大多数的设备编写驱动程序的信息,这些信息迄今仅通过口头或者隐晦的源代码注释被共享。\r\n 本书的作者是Linux社区的领导者。Jonathan Corbet是个不定期的内核开源项目参与者同时还是评价甚高的LWN.net新闻和信息站点的执行编辑。Alessandro Rubini是Linux代码的一个开源提供者同时也是活跃的意大利Linux社区的中心人物。Greg Kroah-Hartman目前是本书描述的USB、PCI和驱动核心子系统相关的内核代码维护者。\r\n 本书新版根据Linux内核2.6.10彻底更新。内核的这个版本更加合理化并简化了普通工作任务的几个方法,比如即插即用、通过sysfs文件系统和用户空间交互、标准总线上的多设备管理。\r\n 你不必是一个内核高手就可以理解并享受本书,所需要的只是C以及Unix系统调用方面的背景知识。在不需要特殊的硬件设备就能编译和运行的详细示例的指引下,你将学会如何给字符设备、块设备和网络接口编写驱动程序。PCI、USB和tty(终端)子系统都单列一章。本书为那些对操作系统的工作机制好奇的人提供了地址空间、异步事件和I/O等方面的阐述。\r\n 本书的主题包括:\r\n * 字符设备、块设备、tty(终端)和网络驱动程序\r\n * 驱动程序调试\r\n * 中断\r\n * 定时问题\r\n * 内存管理和DMA\r\n * 驱动模型和sysfs\r\n * 热插拔设备\r\n * 通用总线,包括SCSI、PCI、USB和IEEE1394(FireWire)的特殊要求。\r\n\r\n
Preface \r\n1. An Introduction to Device Drivers\r\n The Role of the Device Driver \r\n Splitting the Kernel \r\n Classes of Devices and Modules \r\n Security Issues \r\n Version Numbering \r\n License Terms \r\n Joining the Kernel Development Community \r\n Overview of the Book \r\n2. Building and Running Modules\r\n Setting Up Your Test System \r\n The Hello World Module \r\n Kernel Modules Versus Applications \r\n Compiling and Loading \r\n The Kernel Symbol Table \r\n Preliminaries \r\n Initialization and Shutdown \r\n Module Parameters \r\n Doing It in User Space \r\n Quick Reference \r\n3. Char Drivers \r\n The Design of scull \r\n Major and Minor Numbers \r\n Some Important Data Structures 49Char Device Registration \r\n open and release \r\n scull''s Memory Usage \r\n read and write \r\n Playing with the New Devices \r\n Quick Reference \r\n4. Debugging Techniques\r\n Debugging Support in the Kernel \r\n Debugging by Printing \r\n Debugging by Querying \r\n Debugging by Watching \r\n Debugging System Faults \r\n Debuggers and Related Tools \r\n5. Concurrency and Race Conditions\r\n Pitfalls in scull \r\n Concurrency and Its Management \r\n Semaphores and Mutexes \r\n Completions \r\n Spinlocks \r\n Locking Traps \r\n Alternatives to Locking \r\n Quick Reference \r\n6. Advanced Char Driver Operations\r\n ioctl \r\n Blocking I/O \r\n poll and select\r\n Asynchronous Notification \r\n Seeking a Device\r\n Access Control on a Device File\r\n Quick Reference\r\n7. Time, Delays, and Deferred Work\r\n Measuring Time Lapses\r\n Knowing the Current Time\r\n Delaying Execution\r\n Kernel Timers\r\n Tasklets\r\n Workqueues\r\n Quick Reference\r\n8. Allocating Memory \r\n9. Communicating with Hardware \r\n10. Interrupt Handling\r\n11. Data Types in the Kernel\r\n12. PCI Drivers\r\n13. USB Drivers \r\n14. The Linux Device Model\r\n15. Memory Mapping and DMA\r\n16. Block Drivers \r\n17. Network Drivers\r\n18. TTY Drivers \r\nIndex \r\n
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| This is, on the surface, a book about writing device drivers for the Linux system. That is a worthy goal, of course; the flow of new hardware products is not likely to slow down anytime soon, and somebody is going to have to make all those new gadgets work with Linux. But this book is also about how the Linux kernel works and how to adapt its workings to your needs or interests. Linux is an open system; with this book, we hope, it is more open and accessible to a larger community of developers. |
| This is the third edition of Linux Device Drivers. The kernel has changed greatly since this book was first published, and we have tried to evolve the text to match. This edition covers the 2.6.10 kernel as completely as we are able. We have, this time around, elected to omit the discussion of backward compatibility with previous kernel versions. The changes from 2.4 are simply too large, and the 2.4 interface remains well documented in the (freely available) second edition. |
| This edition contains quite a bit of new material relevant to the 2.6 kernel. The discussion of locking and concurrency has been expanded and moved into its own chapter. The Linux device model, which is new in 2.6, is covered in detail. There are new chapters on the USB bus and the serial driver subsystem; the chapter on PCI has also been enhanced. While the organization of the rest of the book resembles that of the earlier editions, every chapter has been thoroughly updated. |
| We hope you enjoy reading this book as much as we have enjoyed writing it. |
| The publication of this edition coincides with my twelth year of working with Linux and, shockingly, my twenty-fifth year in the computing field. Computing seemed like a fast-moving field back in 1980, but things have sped up a lot since then. Keeping Linux Device Drivers up to date is increasingly a challenge; the Linux kernel hackers continue to improve their code, and they have little patience for documentation that fails to keep up. |
| Linux continues to succeed in the market and, more importantly, inthe hearts and minds of developers worldwide. The success of Linux is clearly a testament to its technical quality and to the numerous benefits of free software in general. But the true key to its success, in my opinion, lies in the fact that it has brought the fun back to computing. With Linux, anybody can get their hands into the system and play in a sandbox where contributions from any direction are welcome, but where technical excellence is valued above all else. Linux not only provides us with a top-quality operating system; it gives us the opportunity to be part of its future development and to have fun while we're at it. |
| In my 25 years in the field, I have had many interesting opportunities, from programming the first Cray computers (in Fortran, on punch cards) to seeing the minicomputer and Unix workstation waves, through to the current, microprocessordominated era. Never, though, have I seen the field more full of life, opportunity, and fun. Never have we had such control over our own tools and their evolution. Linux, and free software in general, is clearly the driving force behind those changes. |
| My hope is that this edition helps to bring that fun and opportunity to a new set of Linux developers. Whether your interests are in the kernel or in user space, I hope you find this book to be a useful and interesting guide to just how the kernel works with the hardware. I hope it helps and inspires you to fire up your editor and to make our shared, free operating system even better. Linux has come a long way, but it is also just beginning; it will be more than interesting to watch--and participate in--what happens from here. |
| Alessandro's Introduction |
| I've always enjoyed computers because they can talk to external hardware. So, after soldering my devices for the Apple II and the ZX Spectrum, backed with the Unix and free software expertise the university gave me, I could escape the DOS trap by installing GNU/Linux on a fresh new 386 and by turning on the soldering iron once again. |
| Back then, the community was a small one, and there wasn't much documentation about writing drivers around, so I started writing for Linux Journal. That's how things started: when I later discovered I didn't like writing papers, I left the univeristy and found myself with an O'Reilly contract in my hands. That was in 1996. Ages ago. |
| The computing world is different now: free software looks like a viable solution, both technically and politically, but there's a lot of work to do in both realms. I hope this book furthers two aims: spreading technical knowledge and raising awareness about the need to spread knowledge. That's why, after the first edition proved interesting to the public, the two authors of the second edition switched to a free license, supported by our editor and our publisher. I'm betting this is the right approach tc information, and it's great to team up with other people sharing this vision. |
| I'm excited by what I witness in the embedded arena, and I hope this text helps by doing more; but ideas are moving fast these days, and it's already time to plan for the burth edition, and look for a fourth author to help. |
| It seems like a long time ago that I picked up the first edition of this Linux Device Drivers book in order to figure out how to write a real Linux driver. That first edition was a great guide to helping me understand the internals of this operating system that I had already been using for a number of years but whose kernel had never taken the time to look into. With the knowledge gained from that book, and by read hag other programmers' code already present in the kernel, my first horribly buggy, broken, and very SMP-unsafe driver was accepted by the kernel community into the main kernel tree. Despite receiving my first bug report five minutes later, I was hooked on wanting to do as much as I could to make this operating system the best it could possibly be. |
| I am honored that I've had the ability to contribute to this book. I hope that it enables others to learn the details about the kernel, discover that driver development is not a scary or forbidding place, and possibly encourage others to join in and help in the collective effort of making this operating system work on every computing platform with every type of device available. The development procedure is fun, the community is rewarding, and everyone benefits from the effort involved. |
| Now it's back to making this edition obsolete by fixing current bugs, changing APIs to work better and be simpler to understand for everyone, and adding new features. Come along; we can always use the help. |
| 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 is useful as a starting point for people who want to become kernel hackers but don't know where to start. |
| 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. |
| 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. Therefore, it 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. |
| Organization of the Material |
| The book introduces its topics in ascending order of complexity and is divided into two parts. The first part (Chapters 1-11) begins with the proper setup of kernel modules and goes on to describe the various aspects of programming that you'll need in order to write a full-featured driver for a char-oriented device. Every chapter covers a distinct problem and includes a quick summary at the end, which can be used as a reference during actual development. |
| Throughout the first part of the book, the organization of the material moves roughly from the software-oriented concepts to the hardware-related ones. This organization is meant to allow you to test the software on your own computer as far as possible without the need to plug external hardware into the machine. Every chapter includes source code and points to sample drivers that you can run on any Linux computer. In Chapters 9 and 10, however, we ask you to connect an inch of wire to the parallel port in order to test out hardware handling, but this requirement should be manageable by everyone. |
| The second half of the book (Chapters 12-18) describes block drivers and network interfaces and goes deeper into more advanced topics, such as working with the virtual memory subsystem and with the PCI and USB buses. Many driver authors do not need all of this material, but we encourage you to go on reading anyway. Much of the material found there is interesting as a view into how the Linux kernel works, even if you do not need it for a specific project. |
| In order to be able to use this book, you need to be confident with C programming. Some Unix expertise is needed as well, as we often refer to Unix semantics about system calls, commands, and pipelines. |
| At the hardware level, no previous expertise is required to understand the material in this book, as long as the general concepts are clear in advance. The text isn't based on specific PC hardware, and we provide all the needed information when we do refer to specific hardware. |
| Several free software tools are needed to build the kernel, and you often need specific versions of these tools. Those that are too old can lack needed features, while those that are too new can occasionally generate broken kernels. Usually, the tools provided with any current distribution work just fine. Tool version requirements vary from one kernel to the next; consult Documentation/Changes in the source tree of the kernel you are using for exact requirements. |
| Online Version and License |
| The authors have chosen to make this book freely available under the Creative Commons "Attribution-Share Alike" license, Version 2.0: |
| http://www.oreilly.com/catalog/linuxdrive3 |
| Conventions Used in This Book |
| The following is a list of the typographical conventions used in this book: |
| Used for file and directory names, program and command names, command-line options, URLs, and new terms |
| Used in examples to show the contents of files or the output from commands, and in the text to indicate words that appear in C code or other literal strings |
| Used to indicate text within commands that the user replaces with an actual value |
| Used in examples to show commands or other text that should be typed literally by the user |