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
About the Author
About the Reviewers

Process or thread?

Many embedded developers who are familiar with real-time operating systems (RTOS) consider the Unix process model to be cumbersome. On the other hand, they see a similarity between an RTOS task and a Linux thread and they have a tendency to transfer an existing design using a one-to-one mapping of RTOS tasks to threads. I have, on several occasions, seen designs in which the entire application is implemented with one process containing 40 or more threads. I want to spend some time considering if this is a good idea or not. Let's begin with some definitions.

A process is a memory address space and a thread of execution, as shown in the following diagram. The address space is private to the process and so threads running in different processes. cannot access it. This memory separation is created by the memory management subsystem in the kernel, which keeps a memory page mapping for each process and re-programs the memory management unit on each context switch. I will describe...