min-sized-rust VS Rust-for-Linux

This is a good guide on building small Rust binaries: https://github.com/johnthagen/min-sized-rust

This talks about going to extreme lengths on making the smallest Rust binary possible, 400 bytes when it was written, https://darkcoding.net/software/a-very-small-rust-binary-ind...

The thing is, you lose a lot of nice features when you do this, like panic unwinding, debug symbols, stdlib… for kernel and some embedded development it’s definitely important, but for most use cases, does it matter?

Oh it was 137, haha. I will link you to this older comment of mine: https://news.ycombinator.com/item?id=29408906

See also https://github.com/johnthagen/min-sized-rust

Are you sure? If so then this is awesome news, but I'm a bit confused; the commit in that min-sized-rust repo adding `build-std` to the README was merged in August 2021: https://github.com/johnthagen/min-sized-rust/pull/30

Are you saying that at that point the feature still hadn't "landed in Rust nightly" until recently? If so then what's the difference between a feature just being available in Rust nightly, vs having "landed"?

Rust binaries are by default nowhere close to 500MB. If they are not small enough for you, you can try https://github.com/johnthagen/min-sized-rust. By avoiding the formatting machinery and using `panic_immediate_abort` you can get about the size of C binaries.

A useful reference: https://github.com/johnthagen/min-sized-rust

That must be without stripping. Also there are ways to reduce binary size. See e.g. [min-sized-rust](https://github.com/johnthagen/min-sized-rust). I've gotten stripped binaries of small cli utils less than 400KiB without doing anything special, less than 150 KiB by customizing profile settings and compressing with upx, and less than 30 KiB by replacing the std with the libc as the link shows. Haven't tried with fltk though...

This is not quite what you're asking, but it does also address the underlying concern: https://github.com/johnthagen/min-sized-rust

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.