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

System memory layout - kernel space and user space

Throughout this chapter, terms such as kernel space and user space will refer to their virtual address space. On Linux systems, each process owns a virtual address space. It is a kind of memory sandbox during the life of the process. That address space is 4 GB in size on 32-bit systems (even on a system with physical memory less than 4 GB). For each process, that 4 GB address space is split into two parts:

  • User space virtual addresses
  • Kernel space virtual addresses

The way the split is done depends on a special kernel configuration option, CONFIG_PAGE_OFFSET, which defines where the kernel addresses section starts in a process address space. The common value is 0xC0000000 by default on 32-bit systems, but this may be changed, as is the case for i.MX6 family processors from NXP, which use 0x80000000. In the whole...