If you're building a chip for a server, workstation, laptop, smartphone, then you'll want to adhere to a platform spec profile.

RVA22[0] is the first such profile, and among other important things which go a long way to ease cross-vendor software compatibility, it does require RVA22U and RVA22S, which in turn require a set of extensions.

[0]: https://github.com/riscv/riscv-platform-specs/blob/main/risc...