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

Installing a cross compiler

If you intend to write a C program that is compiled on a certain host system but must execute on another target system, then you need to compile it with what's known as a cross compiler or cross toolchain. For example, in our use case, we want to work on an x86-64 host machine. It could even be an x86-64 guest VM, no issues, but run our code on an ARM-32 target:

  • On Ubuntu, you can install the cross toolchain with the following:
sudo apt install crossbuild-essential-armhf

The preceding command installs an x86_64-to-ARM-32 toolchain appropriate for ARM-32 "hard float" (armhf) systems (such as the Raspberry Pi); this is usually just fine. It results in the arm-linux-gnueabihf-<foo> set of tools being installed; where <foo> represents cross tools such as addr2line, as, g++, gcc, gcov, gprof, ld, nm, objcopy, objdump, readelf, size, strip, and so on. (The cross compiler prefix in this case is arm-linux-gnueabihf-). In addition, though not mandatory, you can install the arm-linux-gnueabi-<foo> cross toolset like this:

sudo apt install gcc-arm-linux-gnueabi binutils-arm-linux-gnueabi
  • On Fedora, you can install the cross toolchain with the following:
sudo dnf install arm-none-eabi-binutils-cs-<ver#> arm-none-eabi-gcc-cs-<ver#>
For Fedora Linux, the same tip as earlier applies – use the Tab key to help auto-complete the command.

Installing and using a cross toolchain might require some reading up for newbie users. You can visit the Further reading section where I have placed a few useful links that will surely be of great help.