Comment by cies
10 months ago
> As a pilot program, R4L should have graduated or ended a long time ago.
Disagree. These things take time. Linus knows that, and as I see it, he's giving it the time it needs. "After years of active development" we've only recently arrived at a point where actual driver development in Rust is possible.
> We all know [Linus'] stance on C++
Yes. And looking back I think that was a good stance. C++ is not for kernels: the language is too big, containing features that don't fit well with kernel development, thereby inviting all kinds of discussion not conductive to kernel development.
Rust is another story. Rust has potential to bring benefits to the kernel. I think Linus knows that.
Off-topic: I'm looking forward to an --largely automated (maybe with use of LLMs)-- port of the kernel in Zig. Just because I think the developer ergonomics of Zig are so much better than C. Not holding my breath: in 10 years or so would be nice.
> C++ is not for kernels
That's a broad generalization to make.
Nintendo's custom OS (Horizon OS, used on Switch and a previous version on 3DS) is almost fully written in C++, including the entire kernel and all drivers.
I agree with you that C++ has plenty of misfeatures. Fortunately, compiler vendors make it fairly easy to dodge the bad parts of the language.
There's C-- (and a few other similar efforts) that are basically C++ with a lot of features forbidden/disabled. I suspect Horizon OS also does this.
I'm not sure if we can still call it C++ in those cases. C++ is more/less a superset of C: we need to know what style of "C++" we're talking about.
3DS HOS was known to be using armcc and Switch HOS is known to be using clang.
Both OSes are huge C++ codebases. Features being disabled or forbidden is a non-userland thing (basically only because resources are constrained. 20KB of exception runtime bload isn't the same thing when you only have 200KB of available RAM vs. when you have 20MB+)
My opinion (and the opinion of people using C++ in such constrained envs.):
* C++ (the language itself along with stuff like <type_traits> and other freestanding headers) is the best thing since sliced bread. So many ways of reducing boilerplate while both writing safe code (RAII) and being mostly in control of produced asm
* most of the other parts of the stdlib are defective
* the committee process sucks, but fortunately compiler vendors allow us to dodge their bad decisions (making #embed available for C++, -fno-exceptions, etc.)