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You're reading from Linux Kernel Programming A comprehensive guide to kernel internals, writing kernel modules, and kernel synchronization

Product type Paperback

Published in Mar 2021

Publisher Packt

ISBN-13 9781789953435

Length 754 pages

Edition 1st Edition

Languages

Tools

Linux

Concepts

System Administration

Author (1):

Kaiwan N. Billimoria

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Table of Contents (19) Chapters

Preface

1. Section 1: The Basics

2. Kernel Workspace Setup FREE CHAPTER

3. Building the 5.x Linux Kernel from Source - Part 1

4. Building the 5.x Linux Kernel from Source - Part 2

5. Writing Your First Kernel Module - LKMs Part 1

6. Writing Your First Kernel Module - LKMs Part 2

7. Section 2: Understanding and Working with the Kernel

8. Kernel Internals Essentials - Processes and Threads

9. Memory Management Internals - Essentials

10. Kernel Memory Allocation for Module Authors - Part 1

11. Kernel Memory Allocation for Module Authors - Part 2

12. The CPU Scheduler - Part 1

13. The CPU Scheduler - Part 2

14. Section 3: Delving Deeper

15. Kernel Synchronization - Part 1

16. Kernel Synchronization - Part 2

17. About Packt

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18. Other Books You May Enjoy

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Deploying our lowlevel_mem_lkm kernel module

Okay, time to see our kernel module in action! Let's build and deploy it on both a Raspberry Pi 4 (running the default Raspberry Pi OS) and on an x86_64 VM (running Fedora 31).

On the Raspberry Pi 4 Model B (here running Raspberry Pi kernel version 5.4.79-v7l+), we build and then insmod(8) our lowlevel_mem_lkm kernel module. The following screenshot shows the output:

Figure 8.5 – The lowlevel_mem_lkm kernel module's output on a Raspberry Pi 4 Model B

Check it out! In step 0 of the output in Figure 8.6 our show_phy_pages() library routine clearly shows that KVA 0xc000 0000 has PA 0x0, KVA 0xc000 1000 has pa 0x1000, and so on, for five pages (along with the PFN on the right); you can literally see the 1:1 identity mapping of physical RAM page frames to kernel virtual pages (in the lowmem region of the kernel segment)!

Next, the initial memory allocation with the ...

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Authors (1)

Kaiwan N. Billimoria

Kaiwan N. Billimoria taught himself BASIC programming on his dad's IBM PC back in 1983. He was programming in C and Assembly on DOS until he discovered the joys of Unix, and by around 1997, Linux! Kaiwan has worked on many aspects of the Linux system programming stack, including Bash scripting, system programming in C, kernel internals, device drivers, and embedded Linux work. He has actively worked on several commercial/FOSS projects. His contributions include drivers to the mainline Linux OS and many smaller projects hosted on GitHub. His Linux passion feeds well into his passion for teaching these topics to engineers, which he has done for well over two decades now. He's also the author of Hands-On System Programming with Linux, Linux Kernel Programming (and its Part 2 book) and Linux Kernel Debugging. It doesn't hurt that he is a recreational ultrarunner too.

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