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

Advantages using sockets

Among others, socket technology provides us with several advantages (over other typical user mode IPC mechanisms such as pipes, SysV IPC/POSIX IPC mechanisms (message queues, shared memory, semaphores, and so on)), as follows:

  • Bidirectional simultaneous data transfer (full duplex).
  • Lossless on the internet, with at least with some transport layer protocols, such as TCP, and of course, on the localhost, which is the case here.
  • High-speed data transfer, especially on localhost!
  • Flow control semantics are always in effect.
  • Asynchronous communication; messages can be queued, so the sender does not have to wait for the receiver.
  • Especially with respect to our topic, in other user<->kernel communication paths (such as procfs, sysfs, debugfs, and ioctl), the user space app must initiate the transfer to the kernel space; with netlink sockets, the kernel can initiate a transfer.
  • Also, with all the other mechanisms we have seen so far (procfs, sysfs, and debugfs...