Link: https://linuxiac.com/systemd-officially-adds-rust-support-for-new-components/

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The systemd project has officially introduced support for developing programs in Rust, following the merger of a pull request submitted by Linux kernel developer Christian Brauner. The change, merged into the project’s main branch, establishes a new development option for systemd while keeping its existing C-based architecture intact.

And before anyone assumes systemd is preparing a complete rewrite in Rust, that’s not the case. The maintainers agreed on a deliberately limited approach: Rust may be used only for new, standalone components that other parts of systemd do not depend on. Existing C code will remain untouched.

Another important decision concerns the build process. Rather than introducing Cargo, Rust’s standard package manager and build tool, systemd continues to use Meson for all builds. This keeps Rust development integrated into the project’s existing build infrastructure.

The implementation also places strict limits on dependencies. Rust programs use the no_std approach, meaning they do not rely on Rust’s standard library or external third-party crates. Instead, they interact with systemd’s existing C libraries through generated bindings.

For memory management, systemd provides its own Rust implementations of common container types, with allocation failures handled explicitly rather than causing the program to abort. The new infrastructure also includes wrappers for logging, command-line argument handling, event processing, and error management, allowing Rust utilities to behave consistently with their C counterparts.

Rust support is optional and automatically detected during configuration. Developers wishing to enable it need Rust 1.85 or later, bindgen 0.71.1 or later, and Meson 1.4 or later. Systems without the required toolchain can continue building systemd without Rust support.

Interestingly, initial tests show that a stripped Rust command-line utility occupies about 32 KB, compared to 20 KB for its C equivalent built with link-time optimization. This gives an early indication of the additional overhead, though the comparison involves only a small test program.

The first planned real-world application of this infrastructure is systemd-keyring-setup, a new utility intended to help manage certificates in Linux kernel keyrings. Its implementation is being developed separately, alongside additional Rust wrappers for systemd’s shared libraries.

For Linux distributions, the change introduces packaging considerations. Builds that enable all available features will need the appropriate Rust compiler and bindgen dependencies or must disable Rust support to avoid build failures.

Whether Rust becomes widely used within systemd will depend on future development, but the necessary groundwork is now in place.

At this point, I think Rust should be installed and available on most distributions. Its just part of Linux now, like C and Python. Maybe this will be, once GCC can compile Rust too.

Those are some wild restrictions. You're using the syntax and presumably compiler (rustc), but almost nothing else from Rust...

Only if it is packaged like python on arch.

I never had so many problems with anything else on linux but pip, npm, and cargo.

I don't think that a package manager and cargo should be included by default, if Rust compiler and the standard library was installed. One can use the compiler rustc without Cargo. Also there are works to create a new independent compiler for the GCC framework, but that takes forever it seems.

That would off course mean that many projects cannot be compiled without a package manager and all their dependencies. But it would make it like Python (and C compilers) be possible to compile individual files. That could make it to a standard way of distributing simple projects which does not require any external libraries at all. This could encourage such projects too, which isn't a bad thing at all to me.

And it just occurred to me that probably some Rust libraries could be installed as a separate Archlinux package too, so you don't need external package manager. Haskell in example does that, and off course Python packages.

Uh, why is Systemd stuff dependent on any specific language, except for (C) kernel calls?

Firefox and Python's cryptography toolchain have a build dependency on Rust, which are two packages that virtually all Linux distributions have packaged. So, some version of the Rust compiler is going to be available on virtually all Linux distributions.

There's no real reason to have the Rust compiler installed on non-dev systems, as you don't need it for running Rust programs (although I kind of assume you know this).
But yeah, it seems to be possible to dynamically link the standard library into Rust programs, so Linux distros could try to share that between them, and then it would effectively be installed by default.

This is about the official systemd repository. They use a mono-repo-approach, where all the official components are in one repository and use the same build system, so adding a second language into that is a bigger hurdle.

If you develop a third-party tool that somehow hooks into systemd, then you can use whatever language you want.

Ah, makes sense, thanks!

While i don't think that a monorepo with no scope guard rails is a good idea.

You don't need to be a developer in order to compile little programs. Like in C it is totally normal to do so, without being a programmer. Just use a make command on a Github project and install it manually. I would put Rust at the same level as C, so yes, most people wouldn't have it installed or need it. But the compile rustc should be packaged by all distributions and it should be part of a meta package for basic development tools (also used by non developers).

In a way that any program could assume everyone on Linux is able to compile with a basic Makefile, like we do this with C in example (if compiler tools are installed). I didn't even think about dynamically linked standard library.

Thats what I mean by "like python on arch"

Well, like with everything now, rust is much more than the compiler, and will need the entire toolchain, so you’d want rustup or pinned toolchain packages so you had access to cargo and the full ecosystem.

Rust has a compiler rustc which does not need the entire toolchain like cargo and eco system. It can be used like Python and C with standard libraries only and adding libraries manually without package manager.

All major distributions ship their own compiled rustc/cargo packages already, and they've done so for years.

And putting rust projects using nightly features aside*, stable rust version updates are much less disruptive than major GCC or clang updates. Breakages are rare, known in advance, and communicated to upstreams before hand (look up "crater" if you want to learn more).

* Not sure if distros package, or need to package any such packages, but I didn't do any surveys on the subject.

That's python's problem. You have no idea how much of a life improvement simply using uv + an older python version (uv natively supports this) is.

You’re using the syntax and presumably compiler (rustc)

but almost nothing else from Rust

waat 😲

Fair enough, I guess.
Personally, I don't really see the point, because there's hardly any projects that can be compiled with just rustc.

I mean, cargo is actually surprisingly useful for normal users, because there's a decent chance you can compile medium-sized Rust projects without having to jump through endless hoops.

But yeah, at that point, you're adding a nontrivial number of megabytes to user installations for something they might not use. I would guess that even just rustc is larger than gcc and clang, since it implements more sophisticated logic...

Personally, I don’t really see the point, because there’s hardly any projects that can be compiled with just rustc.

Because having rustc as a standard tool is not there yet. Off course most don't expect someone to have rustc only on their computer. I love Cargo, don't get me wrong. But I think there could be a rise of non Cargo and library dependency projects in future, if the infrastructure (meaning rustc and the standard library can be expected as standard dependency) is available once.

Just like not every little project of C requires additional dependency trackers. One could download a project from Git and build it with rustc+make and only the dependencies available in your repository. One of the major issues with the public cratesio is, that not everyone wants to depend on it. In example Linux or other projects don't use it (as far as I know). So there might be use cases. Just like we use Python and Haskell without additional libraries, or only install them from our systems repository.

Maybe it shouldn't be installed by default. But having an infastructure with basic system packages to install only "Rust" (rustc+stdlib), no cargo, no rustfmt, no rustup. Maybe this will be available once gcc-rust is ready.

Systemd keeps finding ways to be worse

I think you're clearly clueless and should stop opining on matters you know nothing about.

I think you don't know what you are talking about.

yes, but to manually build packages against libraries yourself would be a nightmare of tooling without cargo.

It's no different than every base-devel and similar package requiring cmake because sure, you could manually run the c/c++ compilers and linkers yourself against every single file, passing in the flags yourself, but that would take an obscene amount of time to manually build and run every compiler command yourself

https://wiki.debian.org/Rust

Debian builds it's own local cargo registry by default. If your distro provides "pinned versions" like I said, you won't need rustup, but you'll still need cargo to do anything beyond a tiny project with no imports, unless you plan on writing async/http/encryption libraries all yourself.

It would be similar to how we build C with make or any other language, using a Makefile in example. In example if the project contains all dependencies in the Git repository already and does not need to download extra dependencies. The Makefile and configuration would handle all of that. Or for projects that do not require dependencies, it would be quite simple compiling.

Debian uses cargo, which is what I would avoid. Cargo is a package manager, that is the exact thing I'm trying to avoid here with the suggestion. I think of dependencies integrated into the system package manager (pacman in example). Debian needs to do this cargo registry, because there is no other infastructure.

Cargo combines the features of a package manager with a build system. You can just used the build system without touching the package manager, which is what Debian and other distros do. But I mean sure, for C there's make cmake automake ninja meson so why not make another for rust

Nobody is talking about making another make tool for Rust.

• You're clueless about how cargo itself wraps/calls rustc. And how other build systems are doing the same, including the one literally mentioned in OP. "Because having rustc as a standard tool is not there yet" is a completely meaningless nonsensical sentence. Neither is rustc lacking in any way, nor is cargo imposes any sort of hard requirement on itself.
• You're clueless about how cargo works. How it natively supports both vendoring (with a single command) and multiple other ways of source replacement.
• You're clueless about the fact that rust statically links std by default, and the fact that the ABI is not stable between major rust versions which is a deliberate choice. And thus, the attempt to draw parallels with "C repo and make" is yet another indicator of your cluelessness.

There is more. But I don't have the time untangle the webs of cluelessness in your comments.