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

Step 6 – generating the initramfs image and bootloader setup

Firstly, please note that this discussion is highly biased toward the x86[_64] architecture. For the typical x86 desktop or server kernel build procedure, this step is internally divided into two distinct parts:

  • Generating the initramfs (formerly called initrd) image
  • (GRUB) bootloader setup for the new kernel image

The reason it's encapsulated into a single step in this recipe for the kernel build process here is that, on the x86 architecture, convenience scripts perform both tasks, giving the appearance of a single step. 

Wondering what exactly this initramfs (or initrd) image file is? Please see the following Understanding the initramfs framework section for details. We'll get there soon.

For now, let's just go ahead and generate the initramfs (short for initial ram filesystem) image file as well as update the bootloader. Performing this on x86[_64] Ubuntu is easily done in one simple...