Add qemu and qemu-nc NixOS configurations

configuration.nix

@@ -5,6 +5,10 @@
     "${modulesPath}/profiles/base.nix"
   ];
 
+  nixpkgs.crossSystem = {
+    system = "riscv64-linux";
+  };
+
   networking.hostName = "nixos-riscv";
 
   nixpkgs.overlays = [ (import ./overlay.nix) ];

flake.nix

@@ -12,43 +12,35 @@
     system = "x86_64-linux";
     overlay = import ./overlay.nix;
     pkgs = import nixpkgs { inherit system; };
-    modules = [
-      # For now we only define a config for VM, later we will want to split
-      # this into different configs.
-      ./vm.nix
-
-      ./configuration.nix
-    ];
   in {
     overlay = import ./overlay.nix;
     nixosConfigurations = {
-      # The cross configuration defines a system that runs in the RISC-V
+      # The qemu configuration defines a system that runs in the RISC-V
       # architecture, but is build from an x86 host machine.
-      cross = nixpkgs.lib.nixosSystem {
+      qemu = nixpkgs.lib.nixosSystem {
         system = "${system}";
-        modules = modules ++ [
+        modules = [
-          {
+          ./configuration.nix
-            nixpkgs.crossSystem = {
+          ./vm.nix
-              gcc.arch = "rv64g";
+        ];
-              gcc.tune = "rv64g";
+      };
-              system = "riscv64-linux";
+
-            };
+      # Same, but disable compressed instructions
-          }
+      qemu-nc = nixpkgs.lib.nixosSystem {
+        system = "${system}";
+        modules = [
+          ./configuration.nix
+          ./vm.nix
+          ./no-compressed.nix
         ];
       };
-      # The native configuration defines the same system, but built from an
-      # RISC-V machine. Not needed for now.
-      #native = nixpkgs.lib.nixosSystem {
-      #  system = "riscv64-linux";
-      #  modules = modules;
-      #};
     };
 
     # A development shell with QEMU ready to boot the RISC-V system in an x86
     # machine.
     devShells.x86_64-linux.default =
     let
-      nixosconf = self.nixosConfigurations.cross;
+      nixosconf = self.nixosConfigurations.qemu-nc;
       syspkgs = nixosconf.pkgs;
       toplevel = nixosconf.config.system.build.toplevel;
       #toplevel = "${nixosconf.config.system.build.vm}/system";

no-compressed.nix

@@ -0,0 +1,9 @@
+{ config, lib, pkgs, modulesPath, ... }:
+
+{
+  nixpkgs.crossSystem = {
+    system = "riscv64-linux";
+    gcc.arch = "rv64g";
+    gcc.tune = "rv64g";
+  };
+}