Book Image

Mastering Embedded Linux Programming - Third Edition

By : Frank Vasquez, Chris Simmonds
5 (3)
Book Image

Mastering Embedded Linux Programming - Third Edition

5 (3)
By: Frank Vasquez, Chris Simmonds

Overview of this book

If you’re looking for a book that will demystify embedded Linux, then you’ve come to the right place. Mastering Embedded Linux Programming is a fully comprehensive guide that can serve both as means to learn new things or as a handy reference. The first few chapters of this book will break down the fundamental elements that underpin all embedded Linux projects: the toolchain, the bootloader, the kernel, and the root filesystem. After that, you will learn how to create each of these elements from scratch and automate the process using Buildroot and the Yocto Project. As you progress, the book will show you how to implement an effective storage strategy for flash memory chips and install updates to a device remotely once it’s deployed. You’ll also learn about the key aspects of writing code for embedded Linux, such as how to access hardware from apps, the implications of writing multi-threaded code, and techniques to manage memory in an efficient way. The final chapters demonstrate how to debug your code, whether it resides in apps or in the Linux kernel itself. You’ll also cover the different tracers and profilers that are available for Linux so that you can quickly pinpoint any performance bottlenecks in your system. By the end of this Linux book, you’ll be able to create efficient and secure embedded devices using Linux.
Table of Contents (27 chapters)
1
Section 1: Elements of Embedded Linux
10
Section 2: System Architecture and Design Decisions
18
Section 3: Writing Embedded Applications
22
Section 4: Debugging and Optimizing Performance

The boot sequence

In simpler times, some years ago, it was only necessary to place the bootloader in non-volatile memory at the reset vector of the processor. NOR flash memory was common at that time and, since it can be mapped directly into the address space, it was the ideal method of storage. The following diagram shows such a configuration, with the Reset vector at 0xfffffffc at the top end of an area of flash memory. The bootloader is linked so that there is a jump instruction at that location that points to the start of the bootloader code:

Figure 3.1 – NOR flash

Figure 3.1 – NOR flash

From that point on, the bootloader code running in NOR flash memory can initialize the DRAM controller so that the main memory – the DRAM – becomes available and then copies itself into the DRAM. Once fully operational, the bootloader can load the kernel from flash memory into DRAM and transfer control to it.

However, once you move away from a simple linearly addressable...