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

Chapter 9. Starting up - the init Program

I looked at how the kernel boots up to the point that it launches the first program, init, in Chapter 4, Porting and Configuring the Kernel and in Chapter 5, Building a Root Filesystem and Chapter 6, Selecting a Build System, I looked at creating root filesystems of varying complexity, all of which contained an init program. Now it is time to look at the init program in more detail and discover why it is so important to the rest of the system.

There are many possible implementations of init. I will describe the three main ones in this chapter: BusyBox init, System V init, and systemd. For each one, I will give an overview of how it works and the types of system it suits best. Part of that is balancing the trade-off between complexity and flexibility.