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

Introducing kernel memory allocators

The Linux kernel, like any other OS, requires a sturdy algorithm and implementation to perform a really key task – the allocation and subsequent deallocation of memory or page frames (RAM). The primary (de)allocator engine in the Linux OS is referred to as the PA, or the BSA. Internally, it uses a so-called buddy system algorithm to efficiently organize and parcel out free chunks of system RAM. We will find more on the algorithm in the Understanding and using the kernel page allocator (or BSA) section.

In this chapter and in this book, when we use the notation (de)allocate, please read it as both words: allocate and deallocate.

Of course, being imperfect, the page allocator is not the only or always the best way to obtain and subsequently release system memory. Other technologies exist within the Linux kernel to do so. High on the list of them is the kernel's slab allocator or slab cache system (we use the word...