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

Virtual memory basics

To recap, Linux configures the memory management unit (MMU) of the CPU to present a virtual address space to a running program that begins at zero and ends at the highest address, 0xffffffff, on a 32-bit processor. This address space is divided into pages of 4 KiB by default. If 4 KiB pages are too small for your application, then you can configure the kernel to use HugePages, reducing the amount of system resources needed to access page table entries and increasing the Translation Lookaside Buffer (TLB) hit ratio.

Linux divides this virtual address space into an area for applications, called user space, and an area for the kernel, called kernel space. The split between the two is set by a kernel configuration parameter named PAGE_OFFSET. In a typical 32-bit embedded system, PAGE_OFFSET is 0xc0000000, giving the lower 3 gigabytes to user space and the top gigabyte to kernel space. The user address space is allocated per process so that each process runs in...