Unstable compilers

Posted Sep 25, 2024 17:56 UTC (Wed) by ballombe (subscriber, #9523)
In reply to: Unstable compilers by admalledd
Parent article: Committing to Rust in the kernel

> You could (especially as you approach the modern era) still often *compile* with whatever GCC (and sometimes CLANG) version so long as it was above some horribly old bare minimum, but it was not uncommon to have subtle miscompilations in more esoteric drivers, or flat out some drivers not compiling, etc.

Because all rust compilers are guaranteed to be bug-free ?

to post comments

Unstable compilers

Posted Sep 25, 2024 18:29 UTC (Wed) by admalledd (subscriber, #95347) [Link]

Certainly not, but the stability of `rustc` is often much higher than many give it credit for, and that Rust gives much better ABI(*)/linking guarantees. It is often not plausible to use a different GCC version from what compiled the kernel to compile custom modules for example. Rust can provide much stronger guarantees here by default, though as mentioned in the article there is in-kernel work to be done for the module symbol naming/linking.

Rust in *most* cases will either halt compilation with an Error, and InternalCompilerError, or result in symbols that will fail at linking time instead of (used to be more) commonly "compiling" fine but crashing/failing at runtime or `insmod` time.

* Rust technically has no ABI, but you can expose/use one via various exports/macro things, commonly of course a "c-abi". This is mostly handled by `rust-bindgen` for automation with a dash of human control when required.