The set of RISC-V processors is going to be far more diverse than you are expecting. There's already dozens of open cores, both 32-bit and 64-bit, with varying

The set of RISC-V processors is going to be far more diverse than you are expecting. There's already dozens of open cores, both 32-bit and 64-bit, with varying support of standard extensions. Assume RVG64GBCV, do we skip P, T, Q? What about J (extensions for dynamic language runtimes)? Do we just ignore those capabilities and leave applications to not get the best out of the machine? If we stick to current status quo, of having #ifdef __FEATURE__ scattered through our code, we would want a source based distribution like Gentoo to make sure we get the most out of our machines, so we can check which features are present and set all the required compiler flags. Otherwise, we could have runtime checks for features, but this will require changing the way applications are commonly written, because we don't want to be checking for the presence of features everywhere in code. We only want to check once on application startup.