It's sort of frustrating that none of this information was in the commit
message.
"This code is not ready to be merged into the arch/risc/ directory
because the RISC-V Foundation has not certified the hardware spec yet.
However, the following chips have implemented it ABC12345, ABC6789 and
they've already shipping to thousands of customers since blah blah blah
so we should support it."
I honestly thought it was an issue with the code or the userspace API.