Understanding the Linux Kernel

Overview of the Book

To make life easier, Chapter 1 presents a general picture of what is inside a Unix kernel and how Linux competes against other well-known Unix systems.

The heart of any Unix kernel is memory management. Chapter 2 explains how Intel 80x86 processors include special circuits to address data in memory and how Linux exploits them.

Processes are a fundamental abstraction offered by Linux and are introduced in Chapter 3. Here we also explain how each process runs either in an unprivileged User Mode or in a privileged Kernel Mode. Transitions between User Mode and Kernel Mode happen only through well-established hardware mechanisms called interrupts and exceptions, which are introduced in Chapter 4. One type of interrupt is crucial for allowing Linux to take care of elapsed time; further details can be found in Chapter 5.

Next we focus again on memory: Chapter 6 describes the sophisticated techniques required to handle the most precious resource in the system (besides the processors, of course), that is, available memory. This resource must be granted both to the Linux kernel and to the user applications. Chapter 7 shows how the kernel copes with the requests for memory issued by greedy application programs.

Chapter 8 explains how a process running in User Mode makes requests to the kernel, while Chapter 9 describes how a process may send synchronization signals to other processes. Chapter 10 explains how Linux executes, in turn, every active process in the system ...