Chapter 4. The Linux KernelA Different Perspective

In this chapter

• Background page 66

• Linux Kernel Construction page 70

• Kernel Build System page 79

• Obtaining a Linux Kernel page 96

• Chapter Summary page 97

If you want to learn about kernel internals, many good books are available on kernel design and operation. Several are presented in Section 4.5.1, "Suggestions for Additional Reading," in this and other chapters throughout the book. However, very little has been written about how the kernel is organized and structured from a project perspective. What if you're looking for the right place to add some custom support for your new embedded project? How do you know which files are important for your architecture?

At first glance, it might seem an almost impossible task to understand the Linux kernel and how to configure it for a specific platform or application. In a recent Linux kernel snapshot, the Linux kernel source tree consists of more than 20,000 files that contain more than six million linesand that's just the beginning. You still need tools, a root file system, and many Linux applications to make a usable system.

This chapter introduces the Linux kernel and covers how the kernel is organized and how the source tree is structured. We then examine the components that make up the kernel image and discuss the kernel source tree layout. Following this, we present the details of the kernel build system and the files that drive the kernel configuration and build system. This chapter concludes by examining what is required for a complete embedded Linux system.