Book Image

Linux Kernel Programming

By : Kaiwan N. Billimoria
Book Image

Linux Kernel Programming

By: Kaiwan N. Billimoria

Overview of this book

Linux Kernel Programming is a comprehensive introduction for those new to Linux kernel and module development. This easy-to-follow guide will have you up and running with writing kernel code in next-to-no time. This book uses the latest 5.4 Long-Term Support (LTS) Linux kernel, which will be maintained from November 2019 through to December 2025. By working with the 5.4 LTS kernel throughout the book, you can be confident that your knowledge will continue to be valid for years to come. You’ll start the journey by learning how to build the kernel from the source. Next, you’ll write your first kernel module using the powerful Loadable Kernel Module (LKM) framework. The following chapters will cover key kernel internals topics including Linux kernel architecture, memory management, and CPU scheduling. During the course of this book, you’ll delve into the fairly complex topic of concurrency within the kernel, understand the issues it can cause, and learn how they can be addressed with various locking technologies (mutexes, spinlocks, atomic, and refcount operators). You’ll also benefit from more advanced material on cache effects, a primer on lock-free techniques within the kernel, deadlock avoidance (with lockdep), and kernel lock debugging techniques. By the end of this kernel book, you’ll have a detailed understanding of the fundamentals of writing Linux kernel module code for real-world projects and products.
Table of Contents (19 chapters)
1
Section 1: The Basics
6
Writing Your First Kernel Module - LKMs Part 2
7
Section 2: Understanding and Working with the Kernel
10
Kernel Memory Allocation for Module Authors - Part 1
11
Kernel Memory Allocation for Module Authors - Part 2
14
Section 3: Delving Deeper
17
About Packt

Visualizing the flow via alternate (CLI) approaches

There are, of course, alternate ways to visualize what's running on each processor; we mention a couple here and have saved one other interesting one (LTTng) for Chapter 11, The CPU Scheduler – Part 2, under the Visualization with LTTng and Trace Compass section):

  • With perf(1), again, run the sudo perf sched record command; this records activity. Stop by terminating it with the ^C signal, followed by sudo perf sched map to see a (CLI) map of execution on the processor(s).
  • Some simple Bash scripting can show what's executing on a given core (a simple wrapper over ps(1)). In the following snippet, we show sample Bash functions; for example, the following c0() function shows what is currently executing on CPU core #0, while c1() does the same for core #1:
# Show thread(s) running on cpu core 'n' - func c'n'
function c0()
{
ps -eLF | awk '{ if($5==0) print...