Book Image

Linux Kernel Debugging

By : Kaiwan N. Billimoria
Book Image

Linux Kernel Debugging

By: Kaiwan N. Billimoria

Overview of this book

The Linux kernel is at the very core of arguably the world’s best production-quality OS. Debugging it, though, can be a complex endeavor. Linux Kernel Debugging is a comprehensive guide to learning all about advanced kernel debugging. This book covers many areas in-depth, such as instrumentation-based debugging techniques (printk and the dynamic debug framework), and shows you how to use Kprobes. Memory-related bugs tend to be a nightmare – two chapters are packed with tools and techniques devoted to debugging them. When the kernel gifts you an Oops, how exactly do you interpret it to be able to debug the underlying issue? We’ve got you covered. Concurrency tends to be an inherently complex topic, so a chapter on lock debugging will help you to learn precisely what data races are, including using KCSAN to detect them. Some thorny issues, both debug- and performance-wise, require detailed kernel-level tracing; you’ll learn to wield the impressive power of Ftrace and its frontends. You’ll also discover how to handle kernel lockups, hangs, and the dreaded kernel panic, as well as leverage the venerable GDB tool within the kernel (KGDB), along with much more. By the end of this book, you will have at your disposal a wide range of powerful kernel debugging tools and techniques, along with a keen sense of when to use which.
Table of Contents (17 chapters)
1
Part 1: A General Introduction and Approaches to Kernel Debugging
4
Part 2: Kernel and Driver Debugging Tools and Techniques
11
Part 3: Additional Kernel Debugging Tools and Techniques

Summary

Firstly, congratulations on completing this, our first chapter. Getting started is half the battle! You began by learning a bit about how the word debug came to be – equal parts myth, legend, and truth...

A key section was the brief description of some complex real-world cases of software gone wrong (several of them very unfortunate tragedies), where a software bug (or bugs) proved to be a key factor behind the disaster.

You understood that we're using the latest (at the time of this writing) 5.10 LTS kernel and how to set up the workspace (on x86_64, using either a native Linux system or Linux running as a guest OS). We covered the configuring and building of two custom kernels – a production and a debug one, with the production kernel geared toward high performance and security whereas the debug one was configured with several (most) kernel debug features turned on, in order to help catch bugs. I will assume you've done this for yourself, as future chapters will depend on it.

Finally, and I think very importantly, a few debugging tips and a small checklist wrapped up this chapter. I urge you to read through the tips and checklist often.

In the next chapter, you will learn that there can be, and are indeed, various approaches to debugging the Linux kernel (and its modules); you'll learn about them and which to use.