Book Image

Mastering Embedded Linux Programming

By : Chris Simmonds
Book Image

Mastering Embedded Linux Programming

By: Chris Simmonds

Overview of this book

Mastering Embedded Linux Programming takes you through the product cycle and gives you an in-depth description of the components and options that are available at each stage. You will begin by learning about toolchains, bootloaders, the Linux kernel, and how to configure a root filesystem to create a basic working device. You will then learn how to use the two most commonly used build systems, Buildroot and Yocto, to speed up and simplify the development process. Building on this solid base, the next section considers how to make best use of raw NAND/NOR flash memory and managed flash eMMC chips, including mechanisms for increasing the lifetime of the devices and to perform reliable in-field updates. Next, you need to consider what techniques are best suited to writing applications for your device. We will then see how functions are split between processes and the usage of POSIX threads, which have a big impact on the responsiveness and performance of the final device The closing sections look at the techniques available to developers for profiling and tracing applications and kernel code using perf and ftrace.
Table of Contents (22 chapters)
Mastering Embedded Linux Programming
Credits
Foreword
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Writing a kernel device driver


Eventually, when you have exhausted all the user-space options above, you will find yourself having to write a device driver to access a piece of hardware attached to your device. While this is not the time or place to delve into details, it is worth considering the options. Character drivers are the most flexible and should cover 90% of all your needs; network devices apply if you are working with a network interface, and block devices are for mass storage. The task of writing a kernel driver is complex and beyond the scope of this book. There are some references at the end that will help you on your way. In this section, I want to outline the options available for interacting with a driver—a topic not normally covered—and show you the basic bones of a driver.

Designing a character device interface

The main character device interface is based on a stream of bytes, as you would have with a serial port. However, many devices don't fit this description: a controller...