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

Service supervision

Once we have created service directories with run scripts under /etc/sv and ensured that BusyBox init starts runsvdir, BusyBox runit handles all the rest. That includes starting, stopping, monitoring, and restarting all the services under its control. The runsvdir utility starts a runsv process for each service directory and restarts a runsv process if it terminates. Because run scripts run their respective daemons in the foreground, runsv expects run to block so that when run exits, runsv will restart it automatically.

Service auto-restart is desirable during system startup because run scripts can crash. This is especially true under BusyBox runit where services start virtually simultaneously instead of one after the other. For instance, a service may fail to start when a dependent service or essential system resource (such as a GPIO or device driver) is not yet available. In the next section, I will show you how to express dependencies between services so that...