I had no idea there was an entire OS written in Rust that was this far along. Is all the bootstrapping from assembly directly into Rust, or do they still have a dependency on C and gcc just to get things going?

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yencabulator a day ago | parent | next [-]

Here, make your own "kernel" in a few lines: https://rust-osdev.github.io/uefi-rs/tutorial/app.html

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steveklabnik an hour ago | parent | prev | next [-]

There are pure rust, no c, embedded RTOSes, like Hubris.

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segbrk 3 days ago | parent | prev [-]

Here you go: https://gitlab.redox-os.org/redox-os/kernel/-/blob/master/sr...

	▲	refulgentis 2 hours ago \| parent [-]
		Thanks for the link! For anyone else clicking through: this is the kernel entry point for x86/x86_64. What it shows is a very thin #[naked] inline assembly trampoline (kstart) that sets up the stack and immediately jumps into unsafe extern "C" fn start(), which is pure Rust. So the bootstrap path here is: a few dozen lines of inline asm to Rust, no C. Though it's worth noting this is one file in one component. The kernel entry being C-free doesn't necessarily tell the whole story. If you peek at that directory listing in the blog post, relibc/ is in recipes/core. reblic is Redox's libc replacement, which is mostly Rust, but has historically needed a C compiler for some POSIX compatibility shims. And the bootloader, firmware handoff, and build system are all separate questions. So the short answer to the original question seems to be: the kernel itself bootstraps from minimal inline asm directly into Rust, no C in the path. The full OS build story is probably more nuanced than any single source file can confirm.