OS X and iOS Kernel Programming

Kernel development can be a daunting task and is very different from programming traditional user applications. The kernel environment is more volatile and complex. Extraordinary care must be taken to ensure that kernel code is free of bugs because any issue may have serious consequences to the stability, security, and performance of the system. This book covers the fundamentals necessary to begin programming in the kernel. We cover kernel development from a theoretical and practical point of view. We cover concepts fundamental to kernel development such as virtual memory and synchronization, as well as more practical knowledge. The book primarily focuses on Mac OS X, however the XNU kernel is also used by iOS, and hence the theoretical material in this book will also apply to it. By far the most common reason for doing development within the kernel’s execution environment is to implement a device driver for controlling internal or external hardware devices. Because of this, much of the focus of this book is centred on the development of device drivers. The primary framework for device driver development in the XNU kernel is I/O Kit, which we cover extensively. As theory becomes boring quickly we have provided working code samples which you can play with to learn more or use as a starting point for your own drivers. We hope you have as much fun reading this book as we have enjoyed writing it.