compiler-team VS Rust-for-Linux

> Also, why aren't we size-sorting fields already?

We are for struct/enum fields. https://camlorn.net/posts/April%202017/rust-struct-field-reo...

There's even an unstable flag to help catch incorrect assumptions about struct layout. https://github.com/rust-lang/compiler-team/issues/457

Are you talking about https://github.com/rust-lang/compiler-team/issues/688 ? I think that issue provides a lot of interesting context for this specific improvement.

And mips64, which rustc recently dumped support for after their attempt to extort funding/resources from Loongson failed:

https://github.com/rust-lang/compiler-team/issues/648

This is the biggest problem with the LLVM mentality: they use architecture support as a means to extract support (i.e. salaried dev positions) from hardware companies.

GNU may have annoyingly-higher standards for merging changes, but once it's in there and supported they will keep it for the long haul.

See https://github.com/rust-lang/compiler-team/issues/688

The work has been going on for some time now and it seems we are quite close to it being enabled as a default for nightly builds, I am super thrilled upwards of 20% faster clean builds and possibly more are on the horizon. Hope everything works out without triggering some unseen ICE. https://github.com/rust-lang/compiler-team/issues/681 Edit: If you want to discuss this feature reach out on Zulip

I'd recommend reading the MCP[1] they linked regarding the decision as well as their target tier policy [2].

They are dropping tier 1 support for Win 7 and Win 8. That means they are no longer going to guarantee that the project builds on those platforms and passes all tests via CI.

As long as it is feasible they will probably keep CI runs for those platforms and if interested parties step up and provide sufficient maintenance support, it will remain tier 2. i.e a guarantee that it builds on those platforms via CI but not necessarily that all features are supported and guaranteed via passing tests.

If interested parties can provide sufficient maintenance that all tests continue passing, it will be tier 1 in all but name. However the rest of the development community won't waste their time with issues like Win 7 and 8's partial support for UTF-8.

And once CI stops being feasible for the compiler team to host, it'll drop down to tier 3. If there's sufficient interest from the community towards maintaining these targets, in practice you should see comparable support to with tiers 1 or 2 however now any CI will be managed externally by the community and the compiler team will stop worrying about changes that could break compilation on those targets.

TLDR: They aren't saying "it'll no longer work" but rather "if you want it to stay maintained for these targets, you have to pitch in dev hours to maintain it and eventually support the infrastructure to do this because we don't see a reason to continue doing this". So if you care for these targets, you'll have to contribute to keep it maintained.

[1]: https://github.com/rust-lang/compiler-team/issues/651

(The already broken) XP support was removed almost 3 years ago: https://github.com/rust-lang/compiler-team/issues/378

Rust is backwards compatible when you stick to stable features, but the kernel uses unstable features that can and do incur breaking changes.

https://github.com/Rust-for-Linux/linux/issues/2

> How would this work?

Don't know exactly what you're asking.

> And why would it be a better idea?

Poorly written device drivers are a significant attack vector. It's one of the reasons Linux is now exploring using Rust for its own device drivers.[0] You may be asking -- why Rust and not some other language? Rust has many of the performance and interoperability advantages of C and C++, but as noted, makes certain classes of memory safety issues impossible. Rust also has significant mindshare among systems programming communities.

[0]: https://rust-for-linux.com

Ctrl-F "rust"

https://rust-for-linux.com/ links to LWN articles at https://lwn.net/Kernel/Index/#Development_tools-Rust that suggest that only basic modules are yet possible with the rust support in Linux kernels 6.2 and 6.3.

Rust-for-linux links to the Android binder module though:

> Android Binder Driver: This project is an effort to rewrite Android's Binder kernel driver in Rust.

> Motivation: Binder is one of the most security and performance critical components of Android. Android isolates apps from each other and the system by assigning each app a unique user ID (UID). This is called "application sandboxing", and is a fundamental tenet of the Android Platform Security Model.

> The majority of inter-process communication (IPC) on Android goes through Binder. Thus, memory unsafety vulnerabilities are especially critical when they happen in the Binder driver

... "Rust in the Linux kernel" (2021) https://security.googleblog.com/2021/04/rust-in-linux-kernel... :

> [...] We also need designs that allow code in the two languages to interact with each other: we're particularly interested in safe, zero-cost abstractions that allow Rust code to use kernel functionality written in C, and how to implement functionality in idiomatic Rust that can be called seamlessly from the C portions of the kernel.

> Since Rust is a new language for the kernel, we also have the opportunity to enforce best practices in terms of documentation and uniformity. For example, we have specific machine-checked requirements around the usage of unsafe code: for every unsafe function, the developer must document the requirements that need to be satisfied by callers to ensure that its usage is safe; additionally, for every call to unsafe functions (or usage of unsafe constructs like dereferencing a raw pointer), the developer must document the justification for why it is safe to do so.

> We'll now show how such a driver would be implemented in Rust, contrasting it with a C implementation. [...]

This guide with unsafe rust that calls into the C, and then with next gen much safer rust right next to it would be a helpful resource too.

What of the post-docker container support (with userspaces also written in go) should be cloned to rust first?

Rust-for-Linux issue tracker

Yes, I definitely agree that it's a problem that pr_info implicitly wraps its arguments in unsafe {}. I wrote my own Pull Request with a trival fix.

Note that this template won't work with Linux 6.1, which has very minimal Rust support. You'll want the RustForLinux tree, or maybe Linux 6.2.

You can join Rust for Linux zulip chat by requesting invite using the link in https://github.com/Rust-for-Linux/linux 's README.