On Mon, Oct 23, 2023 at 11:06:32AM -0400, Will Hawkins wrote: > Can we look to either RISC-V or ARM for prior art in how they worked > different versions and compliance levels? I am happy to amass some > documentation about their processes/procedures if you think that it > would help! I don't know arm to well. x86 is mostly discoverable by bits set in the cpuid leaves, and RISC-V has formal extensions, initially letter and after they noticed that isn't fine grained enough a lot of Z-prefixed ones. I think RISC-V is a good starting point: https://en.wikichip.org/wiki/risc-v/standard_extensions we need to be very careful on what are good scopes for extensions so they are on the one hand useful, but on the other hand not too many of them so that we stop being easily interoperable. As seen in the other branch of this discussion we should also thing a bit of what is supported by existing implementations. I don't think it is a non-startert if they become non-compliant, but we need to weight this very carefully.
