Linux Kernel in a Nutshell is now Creative Commons: free pdf download
Written by a leading developer and maintainer of the Linux kernel, Linux Kernel in a Nutshell is a comprehensive overview of kernel configuration and building, a critical task for Linux users and administrators.The book is available for download in either PDF or DocBook format for the entire book, or by the individual chapter.
To quote of the book’s author:
If you want to know how to build, configure, and install a custom Linux kernel on your machine, buy this book. It is written by someone who spends every day building, configuring, and installing custom kernels as part of the development process of this fun, collaborative project called Linux. I’m especially proud of the chapter on how to figure out how to configure a custom kernel based on the hardware running on your machine. This is an essential task for anyone wanting to wring out the best possible speed and control of your hardware.