Book Image

Mastering Linux Device Driver Development

By : John Madieu
Book Image

Mastering Linux Device Driver Development

By: John Madieu

Overview of this book

Linux is one of the fastest-growing operating systems around the world, and in the last few years, the Linux kernel has evolved significantly to support a wide variety of embedded devices with its improved subsystems and a range of new features. With this book, you’ll find out how you can enhance your skills to write custom device drivers for your Linux operating system. Mastering Linux Device Driver Development provides complete coverage of kernel topics, including video and audio frameworks, that usually go unaddressed. You’ll work with some of the most complex and impactful Linux kernel frameworks, such as PCI, ALSA for SoC, and Video4Linux2, and discover expert tips and best practices along the way. In addition to this, you’ll understand how to make the most of frameworks such as NVMEM and Watchdog. Once you’ve got to grips with Linux kernel helpers, you’ll advance to working with special device types such as Multi-Function Devices (MFD) followed by video and audio device drivers. By the end of this book, you’ll be able to write feature-rich device drivers and integrate them with some of the most complex Linux kernel frameworks, including V4L2 and ALSA for SoC.
Table of Contents (19 chapters)
1
Section 1:Kernel Core Frameworks for Embedded Device Driver Development
6
Section 2: Multimedia and Power Saving in Embedded Linux Systems
13
Section 3: Staying Up to Date with Other Linux Kernel Subsystems

Linux kernel tracing and performance analysis

Though debugging by printing covers most of the debugging needs, there are situations where we need to monitor the Linux kernel at runtime to track strange behavior, including latencies, CPU hogging, scheduling issues, and so on. In the Linux world, the most useful tool for achieving this is part of the kernel itself. The most important is ftrace, which is a Linux kernel internal tracing tool, and is the main topic of this section.

Using Ftrace to instrument the code

Function Trace, in short Ftrace, does much more than what its name says. For example, it can be used to measure the time it takes to process interrupts, to track time-consuming functions, calculate the time to activate high-priority tasks, to track context switches, and much more.

Developed by Steven Rostedt, Ftrace has been included in the kernel since version 2.6.27 in 2008. This is the framework that provides a debugging ring buffer for recording data. This data...