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

Address translation and MMU

Virtual memory is a concept, an illusion given to a process so it thinks it has large and almost infinite memory, and sometimes more than the system really has. It is up to the CPU to make the conversion from virtual to physical address every time you access a memory location. That mechanism is called address translation, and is performed by the Memory Management Unit (MMU), which is a part of the CPU.

MMU protects memory from unauthorized access. Given a process, any page that needs to be accessed must exist in one of the process VMAs, and thus must live in the process page table (every process has its own).

Memory is organized by chunks of fixed size named pages for virtual memory and frames for physical memory, sized 4 KB in our case. Anyway, you do not need to guess the page size of the system you write the driver for. It is defined and accessible...