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Linux Kernel Programming

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
Author (1):
Kaiwan N. Billimoria Kaiwan N. Billimoria
Profile icon Kaiwan N. Billimoria
Toc

Table of Contents (19) Chapters close

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 18. Other Books You May Enjoy

Trying out the kernel module to print process context info

We build our current_affair.ko kernel module (we don't show the build output here) and then insert it into kernel space (via insmod(8) as usual). Now let's view the kernel log with dmesg(1), then rmmod(8) it and use dmesg(1) again. The following screenshot shows this:

Figure 6.9 – The output of the current_affairs.ko kernel module

Clearly, as can be seen from the preceding screenshot, the process context – the process (or thread) running the kernel code of current_affairs.ko:current_affairs_init() – is the insmod process (see the output: 'name        : insmod'), and the current_affairs.ko:current_affairs_exit() process context executing the cleanup code is the rmmod process!

Notice how the timestamps in the left column ([sec.usec]) in the preceding figure help us understand...
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