You're reading from Mastering Embedded Linux Programming Create fast and reliable embedded solutions with Linux 5.4 and the Yocto Project 3.1 (Dunfell)

Product type Paperback

Published in May 2021

Publisher Packt

ISBN-13 9781789530384

Length 758 pages

Edition 3rd Edition

Languages

C++

Tools

Linux

Concepts

Embedded Systems

Authors (2):

Frank Vasquez

Mr. Chris Simmonds

View More author details

Table of Contents (27) Chapters

Preface

1. Section 1: Elements of Embedded Linux

2. Chapter 1: Starting Out FREE CHAPTER

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

Making the root filesystem read-only

You need to make your target device able to survive unexpected events, including file corruption, and still be able to boot and achieve at least a minimum level of functionality. Making the root filesystem read-only is a key part of achieving this ambition because it eliminates accidental overwrites. Making it read-only is easy: replace rw with ro on the kernel command line or use an inherently read-only filesystem such as SquashFS. However, you will find that there are a few files and directories that are traditionally writable:

/etc/resolv.conf: This file is written by network configuration scripts to record the addresses of DNS name servers. The information is volatile, so you simply have to make it a symlink to a temporary directory; for example, /etc/resolv.conf -> /var/run/resolv.conf.
/etc/passwd: This file, along with /etc/group, /etc/shadow, and
/etc/gshadow, stores user and group names and passwords. They need to
be symbolically...