tau: Here is a minimal flake that at least evaluates

{
  inputs = {
    nixpkgs.url = "github:AlexandreTunstall/nixpkgs/ghc-cross";
  };

  outputs = { nixpkgs, ... }:
    {
      nixosConfigurations.riscv64 = nixpkgs.lib.nixosSystem {
        modules = [({lib, pkgs, ...}: {
          nixpkgs.crossSystem.system = "riscv64-linux";
          nixpkgs.localSystem.system = "x86_64-linux";
          environment.systemPackages = [
             pkgs.haskell.compiler.native-bignum.ghc948
          ];
          # Dummy values
          fileSystems."/".device  = lib.mkDefault "/dev/sda1";
          boot.loader.grub.device = lib.mkDefault "/dev/sda";
        })];
      };
    };
}

Maybe you can use that to figure out what is going wrong.

In reply to @hive:the-apothecary.club
i looked through the chat and couldn't find any good binary caches, maybe i missed something, but https://github.com/misuzu/nixos-vf2/blob/master/flake.nix#L3 seems to just give a 404 ? at the very least, when trying it i'm still getting the error with ghc so i'm not sure what's going on here

tau you're in luck because I was planning on writing some instructions in the shared notes (see room description) this evening.

I'll let you know when the instructions are ready.

tau Steven Keuchel fgaz the shared notes now have instructions for how to get a working GHC.

(Disclaimer: It's been a while since I first booted GHC and I haven't yet had time to properly test the instructions.)

Wait until you see how long native GHC takes to build on RISC-V hardware :)

(I doubt you'll be able to build much beyond GHC itself with the cross-compiled GHC.)