Chapter 6. The xnu Kernel

We saw in previous chapters that the Mac OS X kernel environment consists of Mach and BSD derivatives, the I/O Kit driver framework, in-kernel libraries, loadable I/O Kit drivers, and other loadable extensions. Although the Darwin xnu package contains only about half the code that potentially runs in the kernel environment, we will consider xnu to be the kernel. In this chapter, we will look at several abstractions and mechanisms in xnu, while deferring subsystem-specific details to later chapters.