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 (16 chapters)
15
Index

Summary

The term real-time is meaningless unless you qualify it with a deadline and an acceptable miss rate. When you know that you can determine whether or not Linux is a suitable candidate for the operating system and, if so, begin to tune your system to meet the requirements. Tuning Linux and your application to handle real-time events means making it more deterministic so that it can process data reliably inside deadlines. Determinism usually comes at the price of total throughput so a real-time system is not going to be able to process as much data as a non-real-time system.

It is not possible to provide mathematical proof that a complex operating system like Linux will always meet a given deadline, so the only approach is through extensive testing using tools such as cyclictest and Ftrace, and, more importantly, using your own benchmarks for your own application.

To improve determinism, you need to consider both the application and the kernel. When writing real-time applications, you...