Book Image

Linux Device Drivers Development

By : John Madieu
Book Image

Linux Device Drivers Development

By: John Madieu

Overview of this book

Linux kernel is a complex, portable, modular and widely used piece of software, running on around 80% of servers and embedded systems in more than half of devices throughout the World. Device drivers play a critical role in how well a Linux system performs. As Linux has turned out to be one of the most popular operating systems used, the interest in developing proprietary device drivers is also increasing steadily. This book will initially help you understand the basics of drivers as well as prepare for the long journey through the Linux Kernel. This book then covers drivers development based on various Linux subsystems such as memory management, PWM, RTC, IIO, IRQ management, and so on. The book also offers a practical approach on direct memory access and network device drivers. By the end of this book, you will be comfortable with the concept of device driver development and will be in a position to write any device driver from scratch using the latest kernel version (v4.13 at the time of writing this book).
Table of Contents (23 chapters)
Free Chapter
1
Introduction to Kernel Development

User space and kernel space

The concepts of kernel space and user space are a bit abstract. It is all about memory and access rights. One may consider the kernel to be privileged, whereas the user apps are restricted. It is a feature of a modern CPU, allowing it to operate either in privileged or unprivileged mode. This concept will be clearer to you in Chapter 11, Kernel Memory Management:

User space and kernel space

The preceding diagram introduces the separation between kernel and user space, and highlights the fact that system calls represent the bridge between them (we discuss this later in this chapter). We can describe each space as follows:

  • Kernel space: This is a set of addresses where the kernel is hosted and where it runs. Kernel memory (or kernel space) is a memory range, owned by the kernel, protected by access flags, preventing any user apps from messing with the...