Linus Torvalds told iTWire in response to queries that Rust support was "not there yet", adding that things were "getting to the point where maybe it might be mergeable for 5.14 or something like that".
Release candidate six of the 5.12 kernel branch came out in the first week of April. Each point release normally has eight weekly releases, with a further fortnight taken before the final release. That means it would take some time for 5.14 to emerge.
The Google post, from Wedson Almeida Filho of its Android team, pointed out that Android now supported Rust for developing the operating system itself.
{loadpisiton sam08}"Related to this, we are also participating in the effort to evaluate the use of Rust as a supported language for developing the Linux kernel. In this post, we discuss some technical aspects of this work using a few simple examples," he wrote. Android uses a modified Linux kernel.
The man trying to bring Rust to Linux, Miguel Ojeda, wrote in a post dated 14 April: "Some of you have noticed the past few weeks and months that a serious attempt to bring a second language to the kernel was being forged. We are finally here, with an RFC that adds support for Rust to the Linux kernel."
He outlined the goals behind the project as follows:
- "By using Rust in the Linux kernel, our hope is that:
- "New code written in Rust has a reduced risk of memory safety bugs, data races and logic bugs overall, thanks to the language properties mentioned below;
- "Maintainers are more confident in refactoring and accepting patches for modules, thanks to the safe subset of Rust;
- "New drivers and modules become easier to write, thanks to abstractions that are easier to reason about, based on modern language features, as well as backed by detailed documentation;
- "More people get involved overall in developing the kernel, thanks to the usage of a modern language; and
- "By taking advantage of Rust tooling, we keep enforcing the documentation guidelines we have established so far in the project. For instance, we require having all public APIs, safety preconditions, `unsafe` blocks and type invariants documented."
Torvalds said that it was still early days for Rust support, "but at least it's in a 'this kind of works, there's an example, we can build on it'."
Asked about a suggestion by a commenter on the Linux Weekly News website, who said, during a discussion on the Google post, "The solution here is simple: just use C++ instead of Rust", Torvalds could not restrain himself from chortling.
"LOL," was his response. "C++ solves _none_ of the C issues, and only makes things worse. It really is a crap language.
"For people who don't like C, go to a language that actually offers you something worthwhile. Like languages with memory safety and [which] can avoid some of the dangers of C, or languages that have internal GC [garbage collection] support and make memory management easier.
"C++ solves all the wrong problems, and anybody who says 'rewrite the kernel in C++' is too ignorant to even know that."
He said that when one spoke of the dangers of C, one was also speaking about part of what made C so powerful, "and allows you to implement all those low-level things efficiently".
Torvalds added: "While I think GC [garbage collection] is a wonderful thing for programming simplicity, it's generally not necessarily something you can do in a low-level system programming. So I'm not saying 'integrated GC' is good for OS kernels, but it's a very good thing in most other situations."
