How to adding a new platfrom into

I was trying to adding a new platform into lib.system (which haven’t been support yet), the information bellow, and i have a little bit confuse about how to do next [maybe BC I don’t know much about Nix]
[1] /proc/cpuinfo:

what i have done:

  1. base on lib/systems/architectures.feature → check if source [1] provide some kinds of feature → None
  2. I have seen the file lib/systems/platform, but confuse about already-valid platform and further elaborates it with, is it means that this file is a kind of final provider, I should finish its bases support like i
    clarify its kernel support, GCC support and then finally finish this part ? So is it rely on ref 3 in source?

i have seem a likely sthing in example as fnloongminipc but it wasn’t useful
BC there is a new Arch, this company provide a specify gcc to support cross compiling