In practice, the Linux community is the wild wild west, and sweeping changes are infamously difficult to achieve consensus on, and this is by far the broadest sweeping change ever proposed for the project. Every subsystem is a private fiefdom, subject to the whims of each one of Linux’s 1,700+ maintainers, almost all of whom have a dog in this race. It’s herding cats: introducing Rust effectively is one part coding work and ninety-nine parts political work – and it’s a lot of coding work. Every subsystem has its own unique culture and its own strongly held beliefs and values.
The consequences of these factors is that Rust-for-Linux has become a burnout machine. My heart goes out to the developers who have been burned in this project. It’s not fair. Free software is about putting in the work, it’s a classical do-ocracy… until it isn’t, and people get hurt. In spite of my critiques of the project, I recognize the talent and humanity of everyone involved, and wouldn’t have wished these outcomes on them. I also have sympathy for many of the established Linux developers who didn’t exactly want this on their plate… but that’s neither here nor there for the purpose of this post, and any of those developers and their fiefdoms who went out of their way to make life difficult for the Rust developers above and beyond what was needed to ensure technical excellence are accountable for these shitty outcomes.
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Here’s the pitch: a motivated group of talented Rust OS developers could build a Linux-compatible kernel, from scratch, very quickly, with no need to engage in LKML politics. You would be astonished by how quickly you can make meaningful gains in this kind of environment; I think if the amount of effort being put into Rust-for-Linux were applied to a new Linux-compatible OS we could have something production ready for some use-cases within a few years.
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Having a clear, well-proven goal in mind can also help to attract the same people who want to make an impact in a way that a speculative research project might not. Freeing yourselves of the LKML political battles would probably be a big win for the ambitions of bringing Rust into kernel space. Such an effort would also be a great way to mentor a new generation of kernel hackers who are comfortable with Rust in kernel space and ready to deploy their skillset to the research projects that will build a next-generation OS like Redox. The labor pool of serious OS developers badly needs a project like this to make that happen.
Follow up to: One Of The Rust Linux Kernel Maintainers Steps Down - Cites "Nontechnical Nonsense", On Rust, Linux, developers, maintainers, and Asahi Lina's experience about working on Rust code in the kernel
Drew DeVault recently wrote a simple but functional UNIX kernel in a new systems programming language named Hare in about a month, which suggests that doing something similar in Rust would be equally feasible. One or two motivated individuals could get something up which is semi-useful (runs on a common x86 PC, has a console, a filesystem, functional if not necessarily high-performance scheduling and enough of the POSIX API to compile userspace programs for), upon which, what remained would be a lot of finishing work (device drivers, networking, and such), though not all of it necessary for all users. Doing this and keeping the goal of making it a drop-in replacement for the Linux kernel (as in, you can have both and select the one you boot into in your GRUB menu; eventually the new one will do enough well enough to replace Linux) sounds entirely feasible, and a new kernel codebase, implemented in a more structured, safer language sounds like it could deliver a good value proposition over the incumbent.
There's Redox OS already headed in that general direction.
There's also this tutorial: https://os.phil-opp.com
Drew mentions this and points out that it's a new OS design and will therefore take a long time. He argues that an OS based on the linux design would be much easier.
I'd recommend spending some time reading about it. It's not as hard as he thinks. Applications developed for Linux are quite easy to port to Redox. It supports many of the same system calls and has a compatible libc implementation. The kernel does have abstractions to ease the porting process. And if you're going to make a new kernel today, you should do it right and make a microkernel like Redox. One of the benefits of having a microkernel is that it doesn't matter what language you write drivers in. They're isolated to their own processes. Rust, C, C++, whatever.