Linus on Rust and the kernel's DMA layer

None of the maintainers are scheming to stop progress. They are working very hard to keep progressing. None of them are "Bullshitters." Linus made a technical decision and communicated it clearly, he didn't "put down the hammer."

However, from what I've seen of Christoph's work over the last few years, a large chunk of what he's been doing appears to have been cleaning up exactly this API mess in C, so I can understand him being touchy.

I do think his reaction was a case of "shoot the messenger", though :-(

Cheers,
Wol

To be fair, while we're calling out over-the-top metaphors, "guerilla warfare" is a bit much.

The dude tried to NACK something outside of his subsystem and was reminded by the person who actually had the authority to NACK anything being pulled into Linus' branch that was not how things work.

He tried to assume a power he never had, and never will have, sure.

If he was in a position to have his NACK have any affect beyond causing a media circus, I'd be more amenable to your metaphorical hyperbole.

But as it stands, this is more of an "old man shakes fist at cloud" situation (and then is reminded by the weather god that he only is in charge of his puddle, that contributes to the humidity levels, sure, but is certainly not in charge of determining what water sources can contribute to cloud formation to _really_ stretch the metaphor), rather than guerilla warfare.

So "a part rewritten in Rust" doesn't count?

Meanwhile, the Linux kernel isn't the only large codebase out there.

(FWIW, I've personally experienced this "rewrite back and forth" on multiple occasions over my career, and it's every bit as awful as Hellwig mentions)

1) You cannot block Rust code that simply calls into your code

2) You can block the inclusion of Rust in the code that you maintain

3) You can mix C and Rust code if everybody agrees on how that will work. It is up to the individual maintainer.

What he does not say is that you can also completely replace a C subsystem with Rust if the powers that be see the Rust implementation as superior. I would expect this to require a better design and not just a re-implementation of the same ideas in a new language. Still, I expect this to happen eventually. Of course, you could completely replace Rust with C as well I would think (again, given the same requirement to be better).

As happens with C code, there will likely be competing implementations at some point that can be optionally compiled in (maybe a Rust scheduler or memory manager). I would think it would be allowed as long as it was possible to build the kernel without it. And, if it is better, the default could change in the future, at which point the kernel could not really be built without it. But that seems a long way away. For one thing, there is not yet a Rust compliler that can target all the platforms that Linux supports.

I know that I've reacted badly to various things in my life and when I've tried to move on to replace that reaction with a better one, I've been really appreciative of people making that easier by putting to one side their own (understandably negative) emotional reactions to mine. The alternative scenario being that the emotional hurt I caused by my immoderate reaction being an impediment to healing and moving onward.

I try (with qualified success!) to live by this. In my experience, the times I give the benefit of the doubt and it turns out to be a mistake are rarer than my instincts expect. Even if the doubt isn't justified, it'll often redirect an unhelpful emotional situation. If the benefit off the doubt isn't justified, and the person you have it to isn't softened by being given it, and continues to be antagonistic, the cost of waiting out another couple of interactions before deciding the problem is not one I can help by being optimistic is really not that much, either.

I often talk of my "Brain Goblins" - those aspects of my thinking/feeling that are immoderate & unwise, and of how "being an adult" means hearing those voices without putting them in charge. It's like when I'm driving and my 4yo says "let's crash the car, it's funny!" and my job is to say "no"[3]. The difference is that the "Brain Goblins" are *internal* and it's easy to forget that they're *still not the ones in charge*!

[1] Generally, and I suspect in this case, this is often fuelled by our quick, strong, but not very moderate/wise emotional reactions.

[2] I.e. one that recognises and acknowledges, but coralles those emotional reactions with the benefit of our wiser and more moderate (but slower and less forceful) *considered* thought process.

[3] True story!