How Do Linux Kernel Drivers Work?

How Do Linux Kernel Drivers Work? - Learning Resource

Рет қаралды 535,795

Күн бұрын

If you want to hack the Kernel, are interested in jailbreaks or just want to understand computers better, Linux Device Drivers is a great book to get you started. I used to learn the basics and in this video I want to share what clicked for me.
LDD Book: lwn.net/Kernel/LDD3/
LDD3 Example Code Updated: github.com/martinezjavier/ldd3
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Пікірлер: 607

@first-thoughtgiver-of-will2456 3 жыл бұрын

I remember my dad, an old school linux military man told me that writing drivers was the "initial task" of many linux programmers. Thank you for sharing your experience.

@wanglin1943 2 жыл бұрын

Most programmers are still writing applications, and a few engineers who write drivers usually work in semiconductor chip manufacturers

@psykjavier Жыл бұрын

@@wanglin1943 for example, an embedded linux engineer who works touching registers of the SOC. and making drivers for a user developer can use it without worry about the details of how to deal with that specific low level procedures.

@mithrandirthegrey7644 10 ай бұрын

It most definitely isn't and shouldn't be. Writing drivers is dangerous if you don't know what you're doing. The idea that some fresh graduate is writing linux drivers for military hardware is down right terrifying. Airplanes would be falling from the sky. No. You should be very comfortable in userspace before you ever venture down to the kernel and start touching hardware.

@crimsomnia1415 9 ай бұрын

@@mithrandirthegrey7644 I'll have to disagree with you there, though I understand where you're coming from. Certainly you shouldn't be trying to make robust computing systems from scratch if you've no idea what you're doing, but the best way to learn is by understanding the core principles first and then build a grasp of understanding more complex systems from there. The deeper you go into the files, systems and hardware, the simpler things become, and at the core of all computing lies nothing else but understanding the concept of "on" and "off". Building system drivers used to be something people with no computing background had to figure out themselves just by the instruction manual (this is how the security firm I work at had to do it when they first started introducing electrical equipment at the company). It's far harder to try and figure out why a projector doesn't work when you have no idea to begin with how it's even *supposed* to work. When you understand the basic principles it's much easier to infer where things might have gone awry.

@mithrandirthegrey7644 9 ай бұрын

@@crimsomnia1415 I don't disagree that writing hardware drivers is a great exercise for tinkerers and an excellent way to learn things like communication stacks and hardware flow. I vehemently disagree that a pimple faced engineer fresh out of college should be writing hardware drivers for military hardware. That sounds scary.

@mrgummage 4 жыл бұрын

Thumbs up for LiveOverflow ASMR where he reads Linux Device Drivers (Third Edition).

@davidalm2148 4 жыл бұрын

Hey @LiveOverflow Regarding 14:30; Python is internally calling the C the standard library's stdio buffered functions (fread/fwrite) which does the buffering which internally makes the syscall specifying the file descriptor, which triggers the char module's read/write function.

@krisavi 4 жыл бұрын

That is true, python is not very efficient code in that sense, but you get the ease of writing code. However for the example he could have done manual flush before closing. To show that you can force the write to disk without waiting for close or buffer to get full. Normally it gets buffer full until write happens to avoid excessive write operations on disk. It is all about optimizing operations and not to cause bunch of writes to take up CPU instructions while there is nothing to write. For such a small example it would have shown it maybe more how things work and even how close is doing the flush automatically doing it in a way more like open -> write -> flush -> write -> close. On windows on the other hand I have noticed that it does not respect flush always (more reliable on linux). There can be few cases where it does not even write to device, even if you call it to do it, I do not know all the specifics. Well nvm... Watched half a minute more and it was there already :D

@michaelandersson6088 4 жыл бұрын

Fun fact: Linux kernel v2.6 has ~8 million lines of code, v5 has ~26 million lines of code :)

@Zooiest 4 жыл бұрын

That’s... A lot... I coded a JS project for ~2 months a few hours per day and it has only 35k lines iirc

@Qizot 4 жыл бұрын

I still don't know how C code can be scaled to this amount

@ehmeth 4 жыл бұрын

Is this where I mention Casey Muratori's "The Thirty-Million Line Problem"?

@alexstone691 4 жыл бұрын

@@Qizot Imagine your worst nightmare but worse But for real C code becomes a mess, i understand why people use it but it feel like its a chore to start a project in c

@masonfuller9823 4 жыл бұрын

hol' up

@delqyrus2619 4 жыл бұрын

I actually searched for something like this for quite a while and now i randomly stumble over it just by subscribing your channel! Thank you! That helps me so much with one of my projects!

@ih8tusernam3s 4 жыл бұрын

Thanks for all your help, been interested in reversing for years and have rarely found a more concise and comprehensive resource.

@tollertup 4 жыл бұрын

i Just followed the code example and was blown away. Great work. A lot of people say making a series out of that would be amazing and I can only agree!

@solveit1304 4 жыл бұрын

This is mindblownig as you said! I never knew how that devices works and acting like a file - thanks for that daily videos, I'm learning so much stuff

@tiaanbasson9092 Ай бұрын

Scott Pilgrim talks about Linux kernel drivers. Good video.

@jordanc.m.6735 4 жыл бұрын

Your enthusiasm is contagious

@daumtto 2 жыл бұрын

Wow, really impressed by the explanation you've provided! I'm taking an embedded software course, and I really needed this!

@roseproctor3177 2 жыл бұрын

your passion is great! I'm still a beginner programmer. I've taken one term of python and two terms of C++ in community college, so there is still a lot here that goes over my head, but it was really valuable to find this tutorial and explanation, and I can guarantee Ill probably revisit this video in the future as this is now a jumping off point to asking even better questions to understand what I need.

@SciCynicalInventing 4 жыл бұрын

This is exactly what I was looking for as Im learning how to make my own kernel modules. Maybe you could expand on building makefiles and cross compiling things as is frequently done when working with embedded linux systems. Great video!

@_framedlife 4 жыл бұрын

I now want a 2hr version of this 😂 this was amazing

@DonEdward 4 жыл бұрын

Thanks for making this video explaining this book. I didn't make it very far! Now i get it more! Please consider going through more of this fascinating series!

@homere3931 4 жыл бұрын

how you went into the library to analyze the makefile, realized that you have that directory on your linux and then just executed it and it works was just amazing :D

@GorczakWiktor 4 жыл бұрын

I'm really glad to have found this channel. Extremely interesting, very straight-foward and substantive :)

@joonasfi 4 жыл бұрын

Great video! It is truly fascinating that one can compose these file and block drivers on top of each other so that a simple open+write to a certain file can go through a Samba client to send the write call to another server, have it written to an ext4 filesystem which uses a virtual block device which stacks in transparent encryption and mirroring to two different underlying disks, which are actually just block devices, or even might span multiple disks via again virtual block devices...

@trickster1833 4 жыл бұрын

At the beginning, is that Ben Eater's 8-bit breadboard computer design?

@joris-rietveld 4 жыл бұрын

Haha I also recognized it, I am currently building my CPU logic but I burned some stuff so waiting for a delivery from china :-)

@ukaszMarianszki 4 жыл бұрын

Yeah, he is building it on streams

@shubham.1172 4 жыл бұрын

I built a similar one on Logisim! Do check it out github.com/shubham1172/SRM

@shubham.1172 3 жыл бұрын

@@zack3g aye, thanks! It would be amazing if we design some high level language for it 🤣

@youdonotknowmyname9663 3 жыл бұрын

@@shubham.1172 Logisim is awsome! And discrete computers are awsome!

@talhadeniz8465 4 жыл бұрын

I love watching tutorial videos with more applicable examples like that. Better than useless entertainment videos.

@DipanjanPatra 4 жыл бұрын

This is one of the most awesome videos to get started with kernel programming! Thanks for this one.

@PhoenixClank 4 жыл бұрын

This is easy enough for me to understand, but still amazing enough to blow my mind.

@DantalionNl 4 жыл бұрын

That is so awesome, I have read tried to read this book in the past but never got far because the examples did not work anymore. Thank you for this video and providing this resource tons of fun writing my own drivers to be had now :)

@akasshjoshhi6926 4 жыл бұрын

My University exams just ended for now. I was wondering what should I learn and bam notification for this video appeared. Thanks for dropping this awesome resource man!

@S1ckB0y 4 жыл бұрын

Thanks for making learning complex stuff enjoyable! Keep it up!

@neetpbg4 4 жыл бұрын

Dude, your enthusiasm is contagious. Nice vid, keep it up!

@soapmcsoaperson 4 жыл бұрын

Hell of a nice coincidence, I had just started reading the first chapter of this book. Thanks for the vid, man

@geodome83 4 жыл бұрын

creepy social media tracking

@alexscarbro796 4 жыл бұрын

This is a very good book and truly insightful. I used it to start writing a driver for a PCIe based FPGA development board.

@adammontgomery7980 4 жыл бұрын

Awesome video, I did the simple hello kernel module a few years ago and was in over my head. I wanted to create a simple way to send commands to an Arduino, ultimately controlling a stepper motor. I thought the best way to do that would be to create a driver and simple "client-side" code to take commands in the terminal, writing to the device "file" to provide a number of steps and direction to the stepper motor. You've re-ignited my interest and I may make another attempt.

@filipsworks 4 жыл бұрын

Knew about linux drivers and fs devs a long before this video but to see an actual example... Exceptional! Thank You!

@cern1999sb 4 жыл бұрын

My 3rd year computer science project for my university course will require me to write Linux device drivers. This looks like a really good place to start. Thanks so much!

@tonyfremont 3 жыл бұрын

I have the first edition of this book, and the "Understanding the Linux Kernel". Those books, starting with Linux in 1994 and reading literally hundreds of Howto documents, and doing a Linux from scratch build, taught me a ton. Too bad that pretty much all of what I learned back then has since been superceded by evolution. Getting X up and running in the 90s was also a major learning experience.

@cBake0 4 жыл бұрын

This was paradigm shifting for me :), been trying to grok device programming for a long time. Though admittedly never focused heavily on the subject, just pieces here and there. Thanks for the video

@burntt999 3 ай бұрын

Omg I’m so pumped up to go back to this book.. you helped me significantly on this!!

@NunoLopes99 4 жыл бұрын

Your passion is contagious!

@wanglin1943 2 жыл бұрын

I have a certain understanding of drivers, and I have worked in semiconductor manufacturers before. This video is a driver getting started video. The reason I like this video is that the English pronunciation of the video owner is clearer and I can understand it better, which helps me practice English well.

@blackmennewstyle 4 жыл бұрын

I really enjoy his extreme enthusiasm

@TheBodgybrothers 4 жыл бұрын

Awesome! Best rundown on kmods ever.

@damnoish 4 жыл бұрын

i wanted to hit the like at least 4 times while watching. would love more of this. thanks.

@sandman0829 2 жыл бұрын

Such a great and extraordinarily helpful video, for less than 20 mins. Thanks :)

@marekunas 4 жыл бұрын

How Linux Works, 2nd Edition: What Every Superuser Should Know by Brian Ward, also a great book regarding an overview of Linux.

@nikhilt3755 4 жыл бұрын

yeah i am reading that from few weeks and about to comment that book in this section GREAT BOOK

@0xssff 4 жыл бұрын

Got any more recommendations?

@nikhilt3755 4 жыл бұрын

@@0xssff Linux bible

@nikhilt3755 4 жыл бұрын

linux programming interface book

@nikhilt3755 4 жыл бұрын

ARCH WIKI this is a website where u can learn a lot

@martipk 4 жыл бұрын

i just finished studying this material this semester, and this was spot on, great video!

@martipk 3 жыл бұрын

@MichaelKingsfordGray what?

@pdigit010 3 жыл бұрын

When I saw the cover of the book I thought it looked familiar.. and guess what I actually still have the printed version and had used it over 15 year ago! Happily surprised to see how younger generations and youtubers are enjoying hacking into the kernel avoiding to just use latest frameworks! Thanks for the video (and to the g recommendation system that made me bump into it!) :)

@danihp9238 4 жыл бұрын

Your passion is a font of inspiration for me, hope you can do more content about kernel development

@ArthurStomp 3 жыл бұрын

Nice introduction! I enjoy videos about what happens under the hood on linux, specially when they are done in such smooth way

@richtourist 4 жыл бұрын

Fantastic video, really enjoy your stuff. The joy in your eyes is great to see.

@psp.youtube 4 жыл бұрын

this is soo cool, what an awesome kickstarter for writing LDD's

@marindraganov8765 3 жыл бұрын

I do like your enthusiasm when you saw your code running in the kernel! LOL!

@matiitpl 4 жыл бұрын

why am I just seeing this now?! Amazing video and your enthusiasm :) love it

@rikilshah 4 жыл бұрын

Thanks for the very simple explanation of such a complex topic!

@1314zerosktr 2 жыл бұрын

Really appreciate the book link, been looking for something like this

@1889990 4 жыл бұрын

Video starts. Me: I'm not sure if he can keep up the high quality of his videos with daily uploads. Also Me 3 Minutes later: Oh damn thats so interesting and well put together. Keep up the good work! I never regret watching a video of yours!

@shubhamchidrawar9477 3 жыл бұрын

Really enjoyed the video... It would be great to have a series of videos for all three types of LDD.

@robbingoossens 4 жыл бұрын

Mate, are you reading my search history or something? I've been searching for a good explanation of Linux kernel drivers for a couple of days now xD

@0xssff 4 жыл бұрын

Same lol, it all started with figuring out what the mknod command does...

@looploopertzg3511 4 жыл бұрын

Google youtube algorithm kindof sold your data...to him...but it's okay

@roshe7199 4 жыл бұрын

haha same!!

@BeHappyTo 4 жыл бұрын

reality is not

@HritikV 4 жыл бұрын

@@looploopertzg3511 We trust him !!

@michalsebek2089 4 жыл бұрын

Wow, it's so interesting. I always love getting known about how all the things, which were always magic to me, work and how they're connected with each other. Then, everything (some of the magic) clears out to me. I really like that feeling. Thank you.

@MikaelFangel 4 жыл бұрын

Thanks for sharing! I'm learning a lot when watching your videos.

@mavhunter8753 4 жыл бұрын

I remember reading this book a few years back. It really is great.

@shire7949 4 жыл бұрын

Hey. I enjoyed the video. I didn't really feel it was 17 minutes long. It went by fast. Just wanted to say this might be a very good, and so far unimplemented type of video format: You pick a free-to-the-public book, like this one, and read/work through it chapter by chapter. Except you might do it in like a live-stream format ? (maybe one livestream per chapter) I know the live part is kinda daunting, but I feel that doing this would either way help you: - You get obviously the benefits from reading/working through the book. - I feel this might attract viewers since in a way, you will pretty much look like you are "noob" while learning. It will show the viewer that learning is a sort of tough process ? And that they shouldn't expect to know it all in one sitting. And in a way, since this actually attracts people, you might feel the freedom of messing up, of not editing, of not having to look too damn professional. Just be yourself, learning. - Get the profit from the views. - I don't know if this one counts but: Sometimes (really uncommon times), knowledgeable viewers might get in the livestream, so if you don't know a certain something, or are working through something they know, they might raise helpful ideas or explanations, thus increasing the dialog, making it more engaging to viewers to stay in the stream. I really wish you could do it with ANY book. Of course copyright :/ (I wonder if it's legal that you could buy the book, and then show it here. Or work through it this way) Maybe you could even do patreon requests every time you want a new book; effectively making us pay for it. Since in the end, you would be providing us with useful info. In the end. You might get a nice catalog of playlists of books you've worked through. Viewers from any point in time [who bought / are interested in a book] can follow along with you in the future. You put a bunch of ads in every live-stream, and PROFIT. Maybe it is nice publicity for the book ? and also for you. So that you can tweet or somehow contact the writers about doing copyright books. Maybe some will allow it? I know for instance there's this open book about reverse engineering, that the guy updates constantly, and he releases totally free. So you might work through it ? learn, and PROFIT. All while making the book more known, increasing the dialogue, etc.

@paulstelian97 4 жыл бұрын

That's actually a really good idea. Since this book is public, there probably wouldn't be any license issues, plus maybe the original authors could explicitly allow it if there was an issue.

@Xorume. 4 жыл бұрын

This is an awesome idea! I'd love to watch it.

@ara0n 4 жыл бұрын

This is a great idea

@TheNewton 4 жыл бұрын

We'll probably start seeing a format in the coming years for quite a number of reasons on top of the ones Shire Grin wrote about. A current example to observe is web development tutorials that heavily rely on the W3C standards docs as a reference but barely mention small parts of it across multiple videos often on one feature of the web standards specifications and actually reading of the full spec is left as an exercise to the reader but most developers never do to their detriment. Some other future predictions: * Barrier to entry to make long format video gets lower and lower due to proliferation of online video platforms and modern hardware * Higher job dissatisfaction, or outright unemployment, lower hours due to increasing automation for knowledge workers to have more free time, that ironically creates a catch-22 of more educational materials to make more knowledge workers to increase automation. * Streaming as a service/culture maturing as an viable industry for self-employment and socializing * The need for more and more content hours to get captive views * Creating longform content is hard to come up with let alone make; enter wikibooks,published papers, etc. * Rejection fatigue from the oversaturation of online "course" services * Students/learners using streaming socialization as a way to hold themselves accountable to learn something on a schedule in a culture that pushes for constant connection(human and network). And or using the recording as an notesystem. * Publishers are always looking for ways to sell more books so on the copyright side of things getting a teachers edition and a deal for content creators to make a streaming "course" of the book with presales of the book as a requirement of "attendance" or as a way to supplement MooC's which have waned in lieu of "course" platforms.

@hiitsrudd8567 4 жыл бұрын

Shire Grin, you nailed how this vid zoomed by, most YT vids are boring & have nothing to say in the end.

@trakeC 3 жыл бұрын

Dude i was just thinking i should learn more about this and this video popped up. Thnx m8

@kfqfguoqf 4 жыл бұрын

Thank you so much for the channel, I keep learning a lot!

@uthoshantm 4 жыл бұрын

Beautiful overview. Thanks!

@konnosgar 8 ай бұрын

Amazing ! Really enlightening, like you said. Thank you so much!

@VideosfromNH 3 жыл бұрын

Nice. I've been meaning to learn about device drivers. This video and the free book is just what I need to get started.

@burntt999 3 ай бұрын

Holy crap… I tried to read this book years ago but was over my head…you just cleared some shit up for me! Bless you sir

@pushkar260 4 жыл бұрын

Daily liveoverflow videos... cool!

@KupriyanovKirill 3 жыл бұрын

Man, you give me so much inspiration!

@jared9190 4 жыл бұрын

You're a great teacher, keep it up!

@lookback6314 Жыл бұрын

Appreciate your hard work, and love your passion 👍

@Nik__._. 2 жыл бұрын

Well, i'm a bit late to the party but this video gave me exactly the missing link I needed to connect some stuff in may thoughts! :) Thank you! Might as well try writing something now.

@RoiEXLab 4 жыл бұрын

Honestly this is probably one of the most interesting videos I watched from you so far. I mean the hacking videos are great too, but I never felt so enlightened 😱

@esaieledouxnjongssikouam9326 3 жыл бұрын

Ohh... very Nice .... but i have a problem .... My lib/modules/.../build doesn't exist...🤤🤤🤤😭😭😭 So i can't modify, create or unload some modules... Please can you help me...!??

@nikhilchouhan1802 Жыл бұрын

@@esaieledouxnjongssikouam9326 You entered the correct kernel version right?

@esaieledouxnjongssikouam9326 Жыл бұрын

@@nikhilchouhan1802 yeah

@osamazaid25 4 жыл бұрын

What a video 👏🏻 Awesome Job brother

@arnonymous7211 4 жыл бұрын

your current video output is insane while maintaining and improving quality. big up bro

@MidnightAhri 4 жыл бұрын

This actually makes a lot of sense tbh, thx for the video ^~^

@tonysu8860 4 жыл бұрын

A bit different than what I expected based on the video''s title... This really doesn't describe or expand on kernel drivers, But as described in the opening minutes the driver interface provides a way to access, manipulate and even write code that can operate against kernel functions. In other words, the kernel driver isn't the real topic of this video but is a sideshow means to the real topic...accessing the kernel. So, although I felt I was misled, This video is still very interesting, educational, clear and well made. Kudos, I think many people can benefit from this.

@linhorse4405 4 жыл бұрын

I really like your 'File' gesture!

@russelljazzbeck 3 жыл бұрын

What a great video, i love your enthusiasm. Thanks!

@zoomer1468 4 жыл бұрын

Thats gold! Thank you for sharing that resources

@msthalamus2172 3 жыл бұрын

I just spent the last few weeks in WDM hell, but I'd never seen Linux driver code before. It's so amazing how much simpler Linux driver code is than the equivalent in Windows!

@Locost59 3 жыл бұрын

Great little video, thanks.

@ericgorder1 3 жыл бұрын

Awesome, now Linux drivers looks fun! Thanks for posting!

@MB-rc8ie 4 жыл бұрын

Wow, I am just now doing a course about writing device drivers with a project at my university, that may be useful, thanks

@salimibrohimi9813 4 жыл бұрын

I enjoyed this video so much. Thank you!

@Gengingen 6 ай бұрын

Thanks for doing this video!

@MrJackyieman 4 жыл бұрын

awesome vid! very clearly and simple

@entropy79 3 жыл бұрын

Beautiful explanation. Thanks !!

@nztuber 4 жыл бұрын

Great stuff. Very clear, thank you.

@motohisamoriya2136 3 жыл бұрын

I wrote the first Linux kernel device driver for the Linux version 2.4.5, SH -3 (Renesas 7709 and 7727) device drivers. I remember compiling and building many times. In Kernel space, there was no convenient crt0 that called the main function, so it was pretty hard. Before that, I had to fix the device drivers for FreeBSD 2.2, but they were completely different, so I had a hard time. The device driver is basically OK if read, write, ioctrl are implemented. As for interrupts, the handler is not too hard to figure out how the interrupt is occurring, but if you didn't follow kmalloc, kfree in that order, it immediately went out of control.

@edouardmalot51 2 жыл бұрын

Really makes me want to read this book

@memoriasIT 4 жыл бұрын

Funny that I was just reading about this haha Great video, this book is definitely awesome

@Dahaksha 4 жыл бұрын

same xD

@jpierce2l33t 2 жыл бұрын

Very informative like all your videos, plus I got a good laugh when you flailed your arms around while saying 'and then, kernel magic happened' LOL

@peterfiser 4 жыл бұрын

Wonderful video, thank you. Editing was done superbly too. I hope you will have a proper office chair one day. That one looks painful to sit on.

@fakhrealam2008 2 жыл бұрын

Love it, thanks for sharing.

@nashaut7635 4 жыл бұрын

If you like Python programming and file interfaces, you might love Python Fuse ( _pip install fuse-python_ ) : write a virtual file interface in Python, straighter to the goal without compiling kernel modules. Thanks a lot for this tutorial. Love it!

@MusikSony 4 жыл бұрын

Nice video ! I´d love to see doing you a whole driver..

@leowright9554 3 жыл бұрын

Amazing, dude!

@0xssff 4 жыл бұрын

Interesting stuff, thank you! ❤

@ESPPsycho 4 жыл бұрын

Dude this is gold and I love you

@damonzh588 3 жыл бұрын

it's an guide for one want to dive into the kernel. before this i didn't know device driver is a good start point. anyway thank you for introduce this book.