cross-posted from: https://lemmy.world/post/25857381
Hellwig is the maintainer of the DMA subsystem. Hellwig previously blocked rust bindings for DMA code, which in part resulted in Hector Martin from stepping down as a kernel maintainer and eventually Asahi Linux as a whole.
A lot of people commenting on this seem to have gaps in their knowledge of what happened. I highly recommend reading the linked email, as it is both short and has valuable context.
A lot of people commenting on this seem to have gaps in their knowledge of what happened
We’re in a Linus-email-🍿-thread, so that kind of goes without saying doesn’t it? 😂
Is there an easy way of seeing the preceding emails in a threaded format?
I read some posted yesterday that were related but it’s damn confusing whether the conversation has been active in between?
On the bottom of the page you have a tree representation of replies, with clickable links to each message. The layout might not work well on mobile with limited screen width though, but you can just click through them.
Linus ain’t wrong tho
I really appreciated him saying ‘I don’t want yes men, I need people to call me on my bullshit, but I’m calling you out on yours’.
I read through the next few replies, and it seems like the anti-rust maintainer just has an axe to grind and can’t stand people working in a language they don’t understand.
He understands Rust and claims to like it. He simply disagrees with the decision to have a mixed language kernel and is trying to unilaterally stop it from happening.
He is totally correct and it is great to see him finally step in to settle this drama. Hopefully it will reduce the level of noise going forward.
Gee Linus you think you could’ve fucking said something before it got to this point?
Sometimes you gotta let people try to resolve things on their own first.
Yah took him long enough and should have never got to this point. Now we have lost a contributer.
We’ve lost two this week
Internal politics is a bitch 😩
What do you mean? He did step in, understood absolutely no context of the issue, told everyone to shut up, and then left without any real input. Fucking joke
Sometimes when you’re celebrating someone’s judgement, don’t shit on their judgement.
Are we hating on Linus here or agreeing with him? I’m so out of the loop.
Agreeing
Excuse me sir why would You ever disagree with our king linus
People really afraid of Rust out here.
I can relate. I can emphasize with someone who’s learned every nuance of a language, and after 30-40 years suddenly these kids come in with their strange hieroglyphics slowly replacing everything you’ve worked on.
Except that’s literally the reality with computers. Everything evolves and things go obsolete. I’m sure the COBOL and Fortran programmers were pissed when the kids started using C too.
It literally wasn’t about Rust specifically though. Christoph literally said it was about anything that was not C, including assembly, C++, brainfuck, or whatever, entering the kernel. Christoph likes Rust. Christoph (rightfully) does not like mixed language codebases for projects as large and important as Linux
(rightfully) does not like mixed language codebases for projects as large and important as Linux
You make it sound like it’s a matter of taste rather than a technical one (and I suspect it actually might be just about taste in the end)
Its a little of column A, little of column B type situation.
Yes, some of it is his taste, but that taste is coming from a technical place. Primarily long term maintainability of the project.
I realize what Linus came out and said outlines that no code is entering Christoph’s part of the project, but Christoph is playing goalie and needs to make sure that never happens in order to keep everything working correctly for a very long time.
Maybe the DMA module gets rewritten completely in Rust one day, but until then, rust modules interfacing with a C-only component seems to be the best for long-term maintenance.
Not his call, as we can see now
But isn’t this in specific just about bindings?
Yea but if someone uses those bindings then you can’t just not support it.
By the time this code gets into a large scale production system it will be 2029. That is when the bugs will come in if someone leveraged the Rust bindings.
You can ask the big company users at that time to contribute their fixes upstream, but if they get resistance because they have relatively junior Rust devs trying to push up changes that only a handful of maintainers understand, the company will just stop upstreaming their changes.
The primary concern that a major open source project like this will have is that the major contributors will decide that interacting with it is more trouble than it is worth. That is how open source projects move to being passion projects and then die when the passion dies.
Instead of thinking about the bindings as part of the sub-system, think of them as part of the driver. That is what Linus is saying here.
The Rust code will be maintained, by those writing Rust code. By those writing the drivers. These are not junior people.
Except the bindings are written so that they can be used not just by this driver but others as well.
If companies write crappy code that calls into these bindings, that is nothing new. They do that today with C. Like C, the code will not be accepted if crappy and / or there is nobody credible to maintain it.
None of this is a good argument for not letting these bindings in.
It appears so now, yes, but when the drama initially came out it sounded like they were asking for a tiny amount of rust in the kernel to make it work, or if not rust, changing the C to tailor it specifically to the rust. Which I think is a reasonable thing to be concerned about from a maintainability perspective long-term, especially if the rust developers decide to leave randomly (Hector’s abrupt quitting over this very issue is a prime example).
A bunch of people were trying to make that argument to explain Hellwig’s disagreement, but it was never the case. His argument amounted to “you can’t make create unified code to reference mine, you must have each driver maintain its own independent calls to my code”.
Rust is straight up better than C. It’s safer and less prone to errors.
It’s not feasible to convert the entire Linux codebase at once. So your options are to either have a mixed codebase, or stick with effectively Cobol into 2020.
Rust is great, but you are not thinking from a long-term project perspective. Rust is safer, but Linux needs to be maintainable or it dies.
Based on what you’re saying, the only way its going to reasonably be converted to Rust is if someone forks Linux and matches all the changes they’re making in C as they happen but converts it all to Rust. Once its all converted and maintainability has been proven, a merge request would need to be made.
That is not how it will happen, if it ever fully converts at all.
Rust will first be added in a way that allows it to run on top of existing C code. That is what we are seeing here with Rust being used to write drivers.
As sub-systems get overhauled and replaced, sometimes Rust will be chosen as the language to do that. In these cases, a sub-system or module will be written in Rust and both C code and Rust code will use it (call into it).
The above is how the Linux kernel may migrate to Rust (or mostly Rust) over time.
As devs get more comfortable, there may be some areas of the kernel that mix C and Rust. This is likely to be less common and is probably the most difficult to maintain.
Nobody wants to rewrite working, solid kernel modules in Rust though. So, it seems very likely that the kernel will remain mostly C for a long, long time. There are no doubt a few areas though where Rust will really shine
No need for a fork or a rewrite.
Anyone got more context on this I can read through? I haven’t kept up with this other than Linus’s notorious attitude.
It’s mostly in that linked thread. The high level of it is a guy wanted to push Rust code. The maintainer said no it would mean the API for this would be tied to Rust and that is unacceptable. It cause another big contributer to throw a fit and Linus said he can’t be everyone’s mom. They kept fighting for like 2 months apparently? Now Linus stepped in, looked at the code and said the Rust code clearly doesn’t impact the API in the way the maintainer was saying it just breaks itself if the maintainers allow changes to the API.
I kinda dislike the idea that it’s cool for people to contribute code that is so easy to break. I have a feeling after it happens a few times they are going to claim that it is being done intentionally and that the slap fights will carry on.
I do not know why you say it is easy to break.
The Rust team are maintaining their side. I do not expect it to break. And the C code that the Rust code depends on is used by lots of other code. It should be a stable interface. Changing the C code just to break the Rust code would break a lot of C code too and upset a lot of folks.
And the who point is to create a more idiomatic interface on the Rust side. So, even if the c interface does change, it may only be a small amount of Rust code that needs to change in response.
Yea and if the Rust developers don’t show up to the show? Rust is a baby and it has done so little on its own. This isn’t a neat little side project, this is code that a major vendor will want to take up and will demand be maintained. There are implications on a global scale.
This is such a red herring.
The Rust side we are talking about here have been involved for years. They have written amazing code (eg. Apple Silicon GPU drivers). There is an official Fedora spin based on their work.
What makes you think any of that is going to go away?
In fact, this whole incident shows their depth as the project lead quit Linux in disgust and was quickly replaced with another talented, dedicated, and proven developer.
There is a lot more drive-by C code you should worry about.
I can understand Hellwig’s fear, though.
From what I gather as a bystander, it’s apparently common that a refactoring in your module that breaks its API will involve fixing all the call-sites to keep the effort on the person responsible for the change. Now the Rust maintainers say “it’s fine; if it breaks, we’ll deal with it” which is theoretically takes away the cross-language issue for the C-maintainer. Practically I can very well see, that this will still cause friction in the future.
Let’s say such a change happens and at that time there’s a bit of time pressure and the capacity on the rust maintainers is thing for whatever reasons. Will they still happily swallow that change or will they start to discuss if it’s really necessary to do that change? And suddenly, the C-maintainer has a political discussion on top of the technical issue they wanted to solve.
As someone who just wants to get shit done, I would definitely have that fear.
(That doesn’t mean it’s still a bullet not worth swallowing. The change overall can still be worth the friction. I am just saying that I think it’s not totally unwarranted that a maintainer feels affected by this even though current pledges from the other parties promise otherwise; this stance can change or at least be challenged over and over.)
Let’s say such a change happens and at that time there’s a bit of time pressure and the capacity on the rust maintainers is thing for whatever reasons. Will they still happily swallow that change or will they start to discuss if it’s really necessary to do that change? And suddenly, the C-maintainer has a political discussion on top of the technical issue they wanted to solve.
This situation could occur even if the code using the API was written in C.
If an API change breaks other downstream kernel code, and that code can’t be fixed in time then they have a conversation about pushing the changes to the next build.
In the end, Linus has already chosen to accept the extra development overhead in using Rust. I think this situation was more about a maintainer, who happens to disagree with the Rust inclusion, using their position to create unnecessary friction for other maintainers.
Isn’t it just to make the code more idiomatic rust side? If there’s breaking api change c side, it’s just a matter of adjusting the interface, it should not involve any grand work, right? The contributor bringing that change over can just ping anyone familiar with the rust interface and that should be the end of it for them, can’t imagine it’d be very involved to fix
Thanks for the summary, I did a bit of reading myself. It’s interesting the dynamics at play here - you’ve got a long, long term contributor in Hellwig who’s been a maintainer since before Rust even existed, then you’ve got quite a few people championing Rust being introduced into the kernel. I feel like Hellwig’s concerns must have more to do with the long term sustainability of the Rust code - like will there be enough Rust developers 10, 20, 30 years down the line. I mean, even if it stays maintained, having multiple languages in a codebase increases complexity and makes it harder to contribute. Then you have Filho resigning from the Rust for Linux project, which in itself kind of calls into question the long term sustainability of the project. It seems like Rust would have quite a few benefits for the Linux kernel, but the question remains of if it’s still gonna be any good in a few decades. This is juicy stuff!
God damn if these Rust glazers are so offended by this, just go work on Redox
You mean the operating system with a cuckold license? Nothx
I’m personally not a fan of permissible licenses, but you don’t need to bring your fetishes up in every conversation.
deleted by creator
Actual Linux news rather than “which distro should I use for gaming and bit torrents?”
New people don’t realize that Linux is really a soap opera with a small software project attached.
That’s not to say any other OS effort is not also a soap opera. I bet Microsoft has its fair share of drama, too; it’s just that no one sees it because the development effort is proprietary.
Linux news
