Good luck to the #CHERI folks at the #RISCV summit this week trying to convince the architecture review board not to mandate a specific capability format in the Y base architecture!
It would be a real shame to standardise a base architecture that is incompatible with accelerators, microcontrollers, or future versions of a Linux-capable system with a richer set of permissions. The Y base should be like the I base: not a stand-alone set of everything you need to build a usable system, but the common subset that every system needs. I hope you can persuade the RISC-V folks that new base architectures should respect the same principles as existing ones.