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

Modern tracing and performance analysis with [e]BPF

An extension of the well-known Berkeley Packet Filter or BPFeBPF is the extended BPF. (FYI, modern usage of the term is simply to refer to it as BPF, dropping the 'e' prefix). Very briefly, BPF used to provide the supporting infrastructure within the kernel to effectively trace network packets. BPF is a very recent kernel innovation – available only from the Linux 4.0 kernel onward. It extends the BPF notion, allowing you to trace much more than just the network stack. Also, it works for tracing both kernel space as well as userspace apps. In effect, BPF and its frontends are the modern approach to tracing and performance analysis on a Linux system.

To use BPF, you will need a system with the following:

Using the BPF kernel feature directly is very hard, so there are several easier front ends to use. Among them, BCC and bpftrace are regarded as useful. Check out the following link to a picture that opens your eyes to just how many powerful BCC tools are available to help trace different Linux subsystems and hardware: https://github.com/iovisor/bcc/blob/master/images/bcc_tracing_tools_2019.png.

Important: You can install the BCC tools for your regular host Linux distro by reading the installation instructions here: https://github.com/iovisor/bcc/blob/master/INSTALL.md. Why not on our guest Linux VM? You can, when running a distro kernel (such as an Ubuntu- or Fedora-supplied kernel). The reason: the installation of the BCC toolset includes (and depends upon) the installation of the linux-headers-$(uname -r) package; this linux-headers package exists only for distro kernels (and not for our custom 5.4 kernel that we shall often be running on the guest).

The main site for BCC can be found at https://github.com/iovisor/bcc.