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You're reading from Linux Kernel Programming

Product type Book

Published in Mar 2021

Publisher Packt

ISBN-13 9781789953435

Pages 754 pages

Edition 1st Edition

Languages

Concepts

System Administration

Author (1):

Kaiwan N. Billimoria

Table of Contents (19) Chapters

Preface

1. Section 1: The Basics

2. Kernel Workspace Setup

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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Trying it out – the user segment

Now, let's go back to our ch7/show_kernel_seg LKM demo program. We have provided a kernel module parameter named show_uservas(defaulting to the value 0); when set to 1, some details regarding the process context's user space are displayed as well. Here's the definition of the module parameter:

static int show_uservas;
module_param(show_uservas, int, 0660);
MODULE_PARM_DESC(show_uservas,
"Show some user space VAS details; 0 = no (default), 1 = show");

Right, on the same device (our Raspberry Pi 3 B+), let's again run our show_kernel_seg kernel module, this time requesting it to display user space details as well (via the aforementioned parameter). The following screenshot shows the complete output:

Figure 7.16 – Screenshot of our show_kernel_seg.ko LKM's output showing both kernel and user VAS details when running on a Raspberry Pi 3B+ with the stock Raspberry Pi 32-bit Linux OS

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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.

See other products by Kaiwan N. Billimoria