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

Introducing device trees


You are almost certainly going to encounter device trees at some point. This section aims to give you a quick overview of what they are and how they work but there are many details that are not discussed.

A device tree is a flexible way to define the hardware components of a computer system. Usually, the device tree is loaded by the bootloader and passed to the kernel, although it is possible to bundle the device tree with the kernel image itself to cater for bootloaders that are not capable of handling them separately.

The format is derived from a Sun Microsystems bootloader known as OpenBoot, which was formalized as the Open Firmware specification, IEEE standard IEEE1275-1994. It was used in PowerPC-based Macintosh computers and so was a logical choice for the PowerPC Linux port. Since then, it has been adapted on a large scale by the many ARM Linux implementations and, to a lesser extent, by MIPS, MicroBlaze, ARC, and other architectures.

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