Writing Device Drivers

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Do I need improvement? Edit the post to answer the question using facts and citations. Finished over a year ago. I plan to get a good driver because of my experience. Currently, I have a MacBook Pro and Ubuntu laptop running on the MacBook mini X. It was a good read and is very well-known. There's a link in Google MacDevCenter. This will be fun. The software I wrote would give me great pleasure.

Starting with the Linux kernel module

Programming guide and related documentation, as well as some basic knowledge of C and Unix.

I should probably look at the other resources on this wiki about kernel device driver writing. Also, I can follow up with a subset of people that I know would be interested in the subject to get their ideas and opinions about what they wanted to see in such a comprehensive book.

It'll be easy to use such helpful information as an expert user. It'd be very interesting to share my experience with those who are currently writing or plan to write device drivers for Linux or any other operating system for embedded devices.

How much time should I allocate every day (e.g., 2 hours) for studying and preparing? There is always enough time if you set your mind to it.

I'm sure many people would be interested in this series of articles/posts. I should probably get more information on the wiki before starting any new topic. Maybe some other people are doing or planning to do something about this - or maybe not... I'll need to find out...

The book is complete today, but I need to make revisions after a certain time has passed, which I am going to do eventually. It'll take some more time, but probably not too much more.

I will continue studying device drivers and making use of the Embedded Software Engineering - Writing Device Drivers links you've given me, thank you!

I should probably read the book before giving any ideas. Thanks for providing such a comprehensive list of resources! I'm sure they'll be very useful when I need to know something more in-depth about device drivers and embedded devices.

Are you looking for a new device driver

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Building the kernel module

Ok, here's a quick test for you. Your goal is to get the device driver acts working generically on all machines without having to make any changes or customizations - can you get it done in under 15 minutes?

Great work! Takes me about 15-20 minutes with some effort. This book will be great for someone who wants to become an expert user in writing and understanding Linux device drivers.

When I started, I didn't know anything about embedded devices and audio playback device invention and their software in general besides my experience with C and Unix systems. However, that was enough to get started studying and eventually learning how to write good device drivers that worked well on most platforms (some people might say "most common" instead of "most platforms").

For example, if you read the source code of a file that already exists and then edit it to function as a device driver - that is not good enough. You need to understand how your operating system works so you can reach your goal efficiently and quickly.

I'm sure many people would be interested in this series of articles/posts. I should probably get more information on the wiki before starting any new topic. Maybe some other people are doing or planning to do something about this - or maybe not... I'll need to find out...

The book describes how to build and test a Linux kernel module and kernel-mode driver without using the Makefile contained in the sample modules provided with the official Kernel sources (here's another one, written by Keith Owens), and without having to download the entire kernel source tree.

Embedded Linux Primer, which I also recommend every reader check out. If you want to know how it all works, read both books before getting started with your device driver project.

For example, if you need to get information about a certain function used in your code from another source besides its man page or official documentation (e.g., other man pages or text files included in the same package), then there are ways of doing that too. Perhaps someone has already collected all relevant information into one place.

Entering and leaving kernel space

That's fine as long as it works as expected - before making any changes, make sure it does what you want! When writing device drivers for Linux, this is pretty much how things usually go... do something first and then fix it later, which is not bad if we're talking about a single function or a small code snippet.

It's good to be prepared for changes and read through the documentation properly before starting a new project. Make sure the information is correct - it's kind of hard to know what you don't know, but some tools can help with that too!

Using the kernel as a library

I've been following some tutorials on how to create Linux kernel modules from scratch using standard C load and unload functions, which is all fine and makes sense, but I'm afraid it doesn't always explain quite enough... another design issue probably.

Your goal is to get the device driver working without having to make any changes or customization - right? If so then this series of articles/posts might not be the best place to start, but you can learn a lot of stuff about the Linux kernel and how it works by doing that anyway.

Writing device drivers with Linux is not necessarily easy - neither for beginners nor advanced programmers - but once you get there it feels rewarding! This series of articles/posts might not be enough to make it happen though...

For example, if you need to get information about a certain function used in your code from another source besides its man page or official documentation (e.g., other man pages or text files included in the same package), then there are ways of doing that too. Perhaps someone has already collected all relevant information into one place.

Creating a kernel module with no external dependencies

This series of articles/posts might not be enough to make you an expert in that area, but it can still help you learn about Linux device drivers and how they work. I should probably get more information on the wiki before starting any new topic. Perhaps other people are doing or planning to do something about this too?

I would suggest reading "Device Drivers" by Jonathan Corbet, Alessandro Rubini, Greg Kroah-Hartman, but there's also a new book from Karim Yaghmour called " Building Embedded Systems ", which is worth checking out as well. You'll need some time to think things through and experiment with different ideas until you've found what works best for your needs...

Linus Torvalds decided to create a new operating system kernel back in 1991, but he also combined different existing libraries and other code snippets from the GNU project. He started by writing everything from scratch, which can be time-consuming, but proved fruitful in the end because it allowed him to add needed features later on without having to re-invent the wheel.

He made use of existing technologies whenever possible while trying to also avoid unnecessary overheads. In addition, he chose C as his programming language, which is often criticized because it's easy to make mistakes and hard for compilers and human beings alike... debugging C programs doesn't always feel rewarding either...

Linux is not the only kernel of its kind, but it's certainly one of the most popular. It doesn't have any licensing fees or limitations, which has helped it become so widespread since 1991. Some people even say that Linux is on course to become the number one operating system...

Linux was first released as version 0.02 on March 14, 1991... Interesting fact: Linus Torvalds started the Linux device driver development off by making a diff of his Minix code and sending it out on December 5th, 1990!

A few days ago I saw this video for the first time on Twitter, but you might want to watch " The Story Of Linux - A 15-Year-Old OS That Changed The World ".

The Linux kernel still needs a lot of work to become the number one, but it's probably only a matter of time before that happens. Besides, there are also other implementations such as GNU Hurd and FreeBSD for a digital signal processor with character device drivers, which both seem very promising.

I'm not into computer programming myself - I barely know how to use gdb when debugging or Valgrind when profiling programs - but it feels nice knowing you can control your computer and do whatever you want with it... make changes if needed by rewriting source code and recompiling the kernel because it doesn't support what you need out-of-the-box (e.g., drivers for certain hardware).

You could say that about any operating system really, but I guess the main difference with Linux is that it's out in the open and completely free to use. You'll need a license if you want to sell or distribute your own modified version of the kernel, but there are no such limitations...

That doesn't mean Linux developers wouldn't appreciate any help, but they're also more likely to be able to fix bugs by themselves since the source code is available and easy to read through. They might even thank you for reporting errors or making suggestions - although I'm not sure how much time and effort they will invest in something that does not affect them directly anyway. After all, everyone has their interests and favorite projects...

It's always great fun reading about other people's opinions on different aspects of life! Whether it's software or hardware, I'm eager to learn more and can often be found trying to figure out why things work the way they do. And since Linux is open source you're guaranteed to have lots of different sources from which you can draw information as needed...

If you belong to a company that might need somebody with your skills, then I suggest looking through various job offers available online - bit by bit if necessary... only apply for those you feel comfortable about!

In any case, whether you go ahead and pursue a career in computer programming now or later on doesn't matter. As long as you continue learning new things and setting high goals for yourself - including becoming a good problem solver - you will be able to handle anything that's thrown your way!

It might not always be easy or even possible to find a good job out there, but if you're passionate and dedicated about anything I'm sure you will eventually succeed and enjoy your work as well. Just don't limit yourself...

Writing device drivers for embedded systems can be one of those types of study that have huge potential in the long run. It's also pretty interesting from my perspective since it allows me to learn more about writing device driver software resides- both manually as well as using scripting languages such as Python. The latter option especially helps when working with various devices that require time-consuming tasks to be completed automatically.

The first book I read on the subject was " Linux Device Drivers " by O'Reilly, which was recently given to me by a friend. It's not bad at all, but I honestly can't remember how much it costs since I don't use Amazon that often - if you're located in Europe then you could try looking for it at various local bookstores instead...

By the way, if anyone knows of any good books on this topic written in German, please recommend one in the comments section! That would be great :)

Anyway, back to embedded hardware programming... As far as I understand it can be argued whether or not writing device drivers is easier when working with Linux than other OSs such as Windows or OS X. For example, take the Windows Driver Kit (WDK) which - according to Wikipedia - seems like an extremely powerful tool. It seems to have several components for different purposes, which makes it easier for developers on that platform to create drivers without too many problems.

As far as I know, one of the main differences between Windows and Linux is related to how generic devices are handled under each OS. For example, PCI cards (e.g., graphics cards) tend to be treated individually since most people only use one at any given time; they tend not to share resources between them or remove/insert their card when it's not needed (otherwise it will take a lot of time and effort to get the machine back up and running again).

On the contrary, USB devices tend to be treated as generic devices since most people use more than one at any given time. This means that they all share the same resources such as interrupts (IRQs) and DMA channels. If you remove/insert such a device while it's still in use then something is likely to go wrong - at least for some types of devices anyway. Either way, if your hardware uses multiple functional units or subsystems then you might find yourself juggling between numerous drivers. Buses, interruptions, I/O memory... Not an easy task for sure!

The book I'm currently reading goes through both possibilities while focusing on the nitty-gritty of writing device drivers. As far as I know, it's one of the only books that goes into every detail along with examples to make things easier for people who are new to this type of work. Even if you can write code in C, C++, or assembly language already then you should still find it useful since all languages are briefly explained along with other concepts such as linking and debugging your code.

There are plenty of chapters available online through Safari, but the table of contents is unfortunately not complete at the moment. Still, even if you don't have access to either resource then just go ahead and read chapter 1 which covers the basic usage of Linux's PCI subsystem. It will prove useful even when working with USB devices since they tend to behave similarly when it comes down to hardware.

Conclusion

The book is very well-written and highly recommended for anyone interested in writing device drivers under Linux - especially if you want to do so without spending a small fortune on licenses or courses. I'm not exactly sure about the price since this is only the 2nd edition and it was published over 4 years ago, but at least one reader mentioned that it can be bought for $45 + shipping which roughly amounts to €39 (including VAT). That isn't much considering that there's plenty of information inside plus tons of practical examples! If you're still unsure then go ahead and read chapters 1-10 (which cover everything from basic PCI usage to DMA transfers as well as S/PDIF support) - chances are you'll end up buying it :D

All things considered, this book is a must-have if you're going to start working with Linux device drivers. Even though it might be a bit outdated in some areas (e.g., v3.9 of the kernel) then you should still find that most concepts will work just fine in the real world - without requiring too much effort from your side! Just take a look at its table of contents and see for yourself...

Device Driver Basics

Introduction to the main issues involved with writing Linux drivers

- an introduction to the main issues involved with writing Linux drivers Memory Management - how memory is used when loading your driver (and why it matters)

- how memory is used when loading your driver (and why it matters) Initialization and Shutdown - working with in-memory structures, initialization/shutdown routines, registering/unregistering...

- working with in-memory structures, initialization/shutdown routines, registering/unregistering... Char Drivers - everything you need to know about char devices; allocating & freeing memory; registers; ioctls; poll() / select() ...

Block Drivers - everything you need to know about block devices; allocating & freeing memory; registers; ioctls; poll() / select() ...

Network Drivers - everything you need to know about network drivers and sockets (PF_PACKET, struct sk_buff ); ioctls...

ATM Drivers - how to work with Asynchronous Transfer Mode hardware, encapsulation/de-encapsulation layers, cell structures... Using the DMA Engines - working with Direct Memory Access hardware such as Intel 8257 and 82577 chipsets. S/PDIF Support - processing of Sony/Philips Digital Interconnect Format data streams. Writing FireWire Drivers - what you need to know when writing drivers for 1394 or i.LINK devices under Linux Device Power Management - low-level hardware power management under Linux - the gory details PCI Subsystem - everything there is to know about writing device drivers for PCI devices Memory Mapped IO - working with legacy non-PCI peripherals from within your driver

Serial Drivers - how to deal with serial ports at a low level, managing interrupts and port I/O, preparing data for transmission... USB Drivers - what you need to know when writing a USB driver; descriptors, endpoints, pipe policies ... GPIO Support - how to work with General Purpose Input Output devices using sysfs; exporting & unexporting device nodes

Interrupt Handling - working with /proc/interrupts, IRQF_SHARED, SA_SHIRQ, SA_INTERRUPT ...

Timer Support - working with /proc/interrupts, timer IRQs and high-resolution kernel timers...

Machine Check Exception - how the dreaded MCE works and what you can do about it if your chipset supports it...

ACPI Support - using Advanced Configuration & Power Interface to detect & support power management; the infamous "suspend" process Under The Hood - introduction to some internal aspects of Linux like modules, system calls, etc.

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