Preface In the spring semester of 1997, we taught a course on operating systems based on Linux 2.0. The idea was to encourage students to read the source code. To achieve this, we assigned term projects consisting of making changes to the kernel and performing tests on the modified version. We also wrote course notes for our students about a few critical features of Linux liketask switching and task scheduling.We continued along this line in the spring semester of 1998, but we moved on to the Linux2.1 development version. Our course notes were becoming larger and larger. In July, 1998 we contacted O'Reilly & Associates, suggesting they publish a whole book on the Linux kernel. The real work started in the fall of 1998 and lasted about a year and a half. We read thousands of lines of code, trying to make sense of them. After all this work, we can say that it was worth the effort. We...