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

Good going! You've just completed the first of many techniques for debugging the kernel. Instrumentation, though deceptively simple, almost always proves to be a useful and powerful debugging technique.

In this chapter, you began by learning the basics regarding the ubiquitous kernel printk(), pr_*(), and dev_*() routines and macros. We then went into more detail about the specific use of these routines to help in debug situations and tips and tricks that will prove useful in debugging your (driver) modules... This included leveraging the kernel's ability to rate-limit printks, often a necessity on high-volume code paths.

The kernel's elegant and powerful dynamic debug framework was the highlight of this chapter. Here, you learned about it, and how to leverage it to be able to toggle your (and indeed the kernel's) debug prints even on production systems, with virtually no performance degradation when turned off.

We finished this chapter with a...