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

Kernel debugging – why there are different approaches to it

When the kernel has an error, a bug, no matter how trivial or non-trivial, the entire system is considered to be in a bad, unrecoverable state and a kernel panic typically ensues – a fatal condition wherein the system generates a brief diagnostic and then simply halts (or, it can be configured to reboot after a timeout). Debugging these scenarios is inherently hard, as, at least on the surface, it appears as though there is no diagnostic information to work with, and even if there were, the system is unresponsive, essentially dead. So how do you retrieve diagnostic information in order to analyze it?

What you will soon realize is that even though there are several techniques, tools, and approaches to kernel debugging, not all of them are suitable for any and all scenarios – the tools or techniques you use are often dictated by the particular scenario you find yourself in.

So what are these scenarios...