Book Image

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization

By : Kaiwan N. Billimoria
Book Image

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization

By: Kaiwan N. Billimoria

Overview of this book

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization is an ideal companion guide to the Linux Kernel Programming book. This book provides a comprehensive introduction for those new to Linux device driver development and will have you up and running with writing misc class character device driver code (on the 5.4 LTS Linux kernel) in next to no time. You'll begin by learning how to write a simple and complete misc class character driver before interfacing your driver with user-mode processes via procfs, sysfs, debugfs, netlink sockets, and ioctl. You'll then find out how to work with hardware I/O memory. The book covers working with hardware interrupts in depth and helps you understand interrupt request (IRQ) allocation, threaded IRQ handlers, tasklets, and softirqs. You'll also explore the practical usage of useful kernel mechanisms, setting up delays, timers, kernel threads, and workqueues. Finally, you'll discover how to deal with the complexity of kernel synchronization with locking technologies (mutexes, spinlocks, and atomic/refcount operators), including more advanced topics such as cache effects, a primer on lock-free techniques, deadlock avoidance (with lockdep), and kernel lock debugging techniques. By the end of this Linux kernel book, you'll have learned the fundamentals of writing Linux character device driver code for real-world projects and products.
Table of Contents (11 chapters)
Section 1: Character Device Driver Basics
User-Kernel Communication Pathways
Handling Hardware Interrupts
Working with Kernel Timers, Threads, and Workqueues
Section 2: Delving Deeper

Other tools

The following are a few tools worth mentioning with regard to capturing and analyzing system latencies (and more):

  • You can learn how to set up and use the powerful Linux Tracing Toolkit next generation (LTTng) toolset to record traces of the system in action. I highly recommend using the superb Trace Compass GUI to analyze it. In fact, in the companion guide Linux Kernel Programming - Chapter 1, Kernel Workspace Setup, in the Linux Tracing Toolkit next generation (LTTng) section, we showed an interesting screenshot (Figure 1.9) of the Trace Compass GUI being used to display and analyze IRQ lines 1 and 130 (the interrupt lines for the i8042 and Wi-Fi chipset on my native x86_64 system, respectively).
  • You can also try using the latencytop tool to determine which kernel ops what user space threads are blocking on. You will have to turn on CONFIG_LATENCYTOP in the kernel config to do this.
  • Besides latency...