There is always a certain amount of tension between the goals of those using older, less-popular architectures and the goals of projects targeting more mainstream users and systems. In many ways, our community has been spoiled by the number of architectures supported by GCC, but a lot of new software is not being written in C—and existing software is migrating away from it. The Rust language is often the choice these days for both new and existing code bases, but it is built with LLVM, which supports fewer architectures than GCC supports—and Linux runs on. So the question that arises is how much these older, non-Rusty architectures should be able to hold back future development; the answer, in several places now, has been “not much”.
The latest issue came up on the Gentoo development mailing list; Michał Górny noted that the Python cryptography library has started replacing some of its C code with Rust, which is now required to build the library. Since the Gentoo Portage package manager indirectly depends on cryptography, “we will probably have to entirely drop support for architectures that are not supported by Rust”. He listed five architectures that are not supported by upstream Rust (alpha, hppa, ia64, m68k, and s390) and an additional five that are supported but do not have Gentoo Rust packages (mips, 32-bit ppc, sparc, s390x, and riscv).