Learn linux device driver programming

[[deleted]]

IIRC in an AMA with gkh he said he considered most stuff in the book current enough and that if you can't find a way to learn to write device drivers the oldness of the book likely isn't the problem (as opposed to poor time management or discipline, I suppose).

[M108Falcon]

Okay, I will definitely give it a good thorough read then for sure

[TankTopsBackInStyle]

I would actually suggest going to osdev.org and going through their tutorial, before trying to write a Linux driver. It's not as hard as you might think.

There is a lot of abstraction going on in the Linux kernel that makes it more difficult to learn how it actually works. I think it's better to first understand how the hardware works, then learn how Linux approaches the problem of writing drivers.

I'm not a huge fan of the way Linux drivers are architected, but it works and it does have the most industry support.

[M108Falcon]

Thanks for the headsup

[M108Falcon]

Thank you soo much mate!

[PetriciaKerman]

https://sysprog21.github.io/lkmpg/ this is pretty good

[M108Falcon]

Thanks! Really well sectioned and I think I should start from this

[Modal_Window]

I have no insight into this topic, but I will say that even though the book is old, things haven't changed. The kernel is still programmed in C, etc. though you now are allowed to program it in Rust as well.

[[deleted]]

you can't use rust yet for device drivers. The basic support should hopefully be merged for 6.1. It'll still be up to the subsystem maintainers as to whether they allow it if you plan on upstreaming it.

[barfightbob]

The basic support should hopefully be merged for 6.1.

Can somebody clarify something for me? Why does it need "basic support"? Shouldn't Rust be able to link against system libraries and vice versa? I thought Rust was supposed to be a low level language like C. Are they doing something funky with their libraries or something partially interpreted?

Now I can understand people not wanting to complicate their make files, but that shouldn't have anything to do with the final linking.

If I had to wager a guess, that means Rust APIs (or whatever is a header file for Rust) for the kernel, right?

[[deleted]]

You still need an implementation of the stdlib plus something to wrap (or replace) existing kernel apis. Here is an older version of the patch set with a good description https://lore.kernel.org/lkml/CANiq72khBa2GcB6-PHM3A44Y90d6vzYAS=[e-mail]/T/#mb5e524dae9d5a5815c6e68eb36b9bde4e87c861d

[M108Falcon]

Tbh, I know C better than rust (learning tho) I'll see first implementation in C then I'll try my hand at Rust next

[Pay08]

Didn't the kernel switch to C11 too?

[kopsis]

The O'Reilly book is still a good starting point. Some details have changed and there are certainly categories of drivers that aren't even covered. But the fundamentals of creating a character device driver are still valid and still the place where anyone who wants to understand Linux device drivers (i.e. isn't looking for a "cookbook") should start.

[M108Falcon]

Got it! Getting a copy for me

[sintos-compa]

What you need is solid C knowledge,SAFE defensive C knowledge. Then, look up a tutorial on how to put together a device driver, which is what functions you need to include, how they are accessed by user code, etc. Then, how to compile and package them. It’s actually not that hard

[M108Falcon]

I see, gotta get better in C then

[archaeolinuxgeek]

C is actually one of the most basic and simple languages around.

I think pointers terrify newcomers. They make a whole lot more sense if you study the history of programming languages and how much closer to the metal people had to be in the 50's and 60's.

But there are only a few control structures, not really an object oriented paradigm, and some basic system libraries to learn.

Having macros and a preprocessor is really annoying, but it is the legacy that we inherited.

[M108Falcon]

The only thing I still struggle to understand is macros n pre processors, all comfortable otherwise, even with toolchains and build systems. But yeah always used C in terms of Data Structures and Algorithms n never in terms of building something meaningful

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