You're reading from Mastering Embedded Linux Programming - Third Edition

Product type Book

Published in May 2021

Publisher Packt

ISBN-13 9781789530384

Pages 758 pages

Edition 3rd Edition

Languages

Concepts

Embedded Systems

Authors (2):

Frank Vasquez

Chris Simmonds

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Table of Contents (27) Chapters

Preface

1. Section 1: Elements of Embedded Linux

2. Chapter 1: Starting Out

3. Chapter 2: Learning about Toolchains

4. Chapter 3: All about Bootloaders

5. Chapter 4: Configuring and Building the Kernel

6. Chapter 5: Building a Root Filesystem

7. Chapter 6: Selecting a Build System

8. Chapter 7: Developing with Yocto

9. Chapter 8: Yocto Under the Hood

10. Section 2: System Architecture and Design Decisions

11. Chapter 9: Creating a Storage Strategy

12. Chapter 10: Updating Software in the Field

13. Chapter 11: Interfacing with Device Drivers

14. Chapter 12: Prototyping with Breakout Boards

15. Chapter 13: Starting Up – The init Program

16. Chapter 14: Starting with BusyBox runit

17. Chapter 15: Managing Power

18. Section 3: Writing Embedded Applications

19. Chapter 16: Packaging Python

20. Chapter 17: Learning about Processes and Threads

21. Chapter 18: Managing Memory

22. Section 4: Debugging and Optimizing Performance

23. Chapter 19: Debugging with GDB

24. Chapter 20: Profiling and Tracing

25. Chapter 21: Real-Time Programming

26. Other Books You May Enjoy

Accessing flash memory from the bootloader

In Chapter 3, All About Bootloaders, I mentioned the need for the bootloader to load kernel binaries and other images from various flash devices, and to perform system maintenance tasks such as erasing and reprogramming flash memory. It follows that the bootloader must have the drivers and infrastructure needed to support read, erase, and write operations on the type of memory you have, whether it be NOR, NAND, or managed. I will use U-Boot in the following examples; other bootloaders follow a similar pattern.

U-Boot and NOR flash

U-Boot has drivers for NOR CFI chips in drivers/mtd and utilizes various erase commands to erase memory and cp.b to copy data byte by byte, programming the flash cells. Suppose that you have NOR flash memory mapped from 0x40000000 to 0x48000000, of which 4 MiB, starting at 0x40040000, is a kernel image. Here, you would load a new kernel into flash using these U-Boot commands: