List extensions and profiles on a RV processor

[lelegard]

Hi,

Just learning RISC-V architecture, with nothing else in hand than Qemu, I tried to find a very synthetic list of ISA extensions and how to characterize them on a given CPU.

I found no such list, except opening many different PDF files and searching into each of them. Therefore, I wrote some simple Python script to do that. You may be interested in reviewing it. Available here: https://github.com/lelegard/riscv-info

I synthesized the list of most extensions and profiles in one single YAML file (the missing list I was looking for). It is probably incomplete. Feel free to supplement it if necessary. If that kind of simple list already exists, I couldn't find it and would be interested in locating it.

There are some obvious limitations. The script works on Linux only and uses the information that the kernel exposes through /proc. If the kernel misses some information, it won't be seen. I should probably write some kernel module to directly peek into the system registers. I have already done that on Arm. This is obviously off-topic here but it demonstrates it can be done.