RHEL Support

I also see hexagon and xtensa in the tier 3 list of the rustc manual, leaving only 7 architectures with no support at all, which are also the ones with very few users these days:

alpha, parisc and superh are old, with the latest CPU cores dating back to 2005, any work going on here is driven by hobbyists, but m68k shows that this may still happen.

arc, microblaze, and nios2 are still available for new designs but most users have moved on to risc-v here, and I don't expect anyone to put money into a rustc port. Nios2 and microblaze are likely to get phased out from the kernel in the next few years. Openrisc is somewhere between those, as a softcore that is not owned by a single company.