add nixos module

base.nix

@@ -1,4 +1,4 @@
-{ config, pkgs, modulesPath, ... }: {
+{ config, pkgs, lib, modulesPath, ... }: {
   fileSystems = {
     "/boot" = {
       device = "/dev/disk/by-label/nixos-boot";
@@ -16,11 +16,50 @@
   system.build.rootFileSystem = pkgs.callPackage (modulesPath + "/../lib/make-ext4-fs.nix") {
     storePaths = with pkgs; [
       config.system.build.toplevel
-      busybox
     ];
     volumeLabel = "nixos-root";
+    populateImageCommands = ''
+      cp ${config.system.build.toplevel}/init ./files/init
+      touch ./files/firstboot
+    '';
   };
 
+  # from https://github.com/NixOS/nixpkgs/blob/e405f30513169feedb64b5c25e7b00242010af58/nixos/modules/installer/sd-card/sd-image.nix#L267
+  boot.postBootCommands = let
+      expandOnBoot = ''
+        # Figure out device names for the boot device and root filesystem.
+        rootPart=$(${pkgs.util-linux}/bin/findmnt -n -o SOURCE /)
+        bootDevice=$(lsblk -npo PKNAME $rootPart)
+        partNum=$(lsblk -npo MAJ:MIN $rootPart | ${pkgs.gawk}/bin/awk -F: '{print $2}')
+
+        # Resize the root partition and the filesystem to fit the disk
+        echo ",+," | sfdisk -N$partNum --no-reread $bootDevice
+        ${pkgs.parted}/bin/partprobe
+        ${pkgs.e2fsprogs}/bin/resize2fs $rootPart
+      '';
+      firstbootFile = "/firstboot";
+    in ''
+      # On the first boot do some maintenance tasks
+      if [ -f ${firstbootFile} ]; then
+        set -euo pipefail
+        set -x
+
+        ${expandOnBoot}
+
+        # TODO what does all this do?
+
+        # Register the contents of the initial Nix store
+        # ${config.nix.package.out}/bin/nix-store --load-db < ${firstbootFile}
+
+        # nixos-rebuild also requires a "system" profile and an /etc/NIXOS tag.
+        # touch /etc/NIXOS
+        # ${config.nix.package.out}/bin/nix-env -p /nix/var/nix/profiles/system --set /run/current-system
+
+        # Prevents this from running on later boots.
+        rm -f ${firstbootFile}
+      fi
+    '';
+
   # system.build.usbImage = pkgs.callPackage ({ stdenvNoCC }: stdenvNoCC.mkDerivation {
   #   name = "nixos-ps4-usbimage";
 

flake.nix

@@ -4,6 +4,11 @@
   };
 
   outputs = { self, nixpkgs }: {
+    nixosModules = rec {
+      ps4 = import ./nixos;
+      default = ps4;
+    };
+  
     nixosConfigurations = {
       "aeolia" = nixpkgs.lib.nixosSystem {
         system = "x86_64-linux";
@@ -15,6 +20,7 @@
             })
           ]; })
           ./aeolia-config.nix
+          ./config.nix
         ];
       };
     };

nixos/default.nix

@@ -0,0 +1,119 @@
+{ lib, config, pkgs, modulesPath, ... }: {
+  options.ps4 = with lib; {
+    enable = mkEnableOption "Build NixOS for Sony PlayStation 4.";
+
+    usbImage = {
+      imageName = mkOption {
+        type = types.str;
+        default = "${config.ps4.usbImage.imageBaseName}-${config.system.nixos.label}.img";
+        description = "Name of the generated image file.";
+      };
+      
+      imageBaseName = mkOption {
+        type = types.str;
+        default = "ps4nixos";
+        description = "Prefix of the name of the generated image file.";
+      };
+    
+      compressImage = mkOption {
+        type = types.bool;
+        default = false;
+        description = "Compress the resulting image with zstd.";
+      };
+
+      bootPartitionSize = mkOption {
+        type = types.int;
+        default = 128;
+        description = "Size of the boot partition, in mebibytes (1024x1024 bytes).";
+      };
+
+      bootPartitionLabel = mkOption {
+        type = types.str;
+        default = "nixos-boot";
+        description = "Label to give the boot partition of the image.";
+      };
+
+      rootPartitionLabel = mkOption {
+        type = types.str;
+        default = "nixos-root";
+        description = "Label to give the root partition of the image.";
+      };
+
+      expandOnBoot = mkOption {
+        type = types.bool;
+        default = true;
+        description = "Whether the image should expand the root partition on first boot.";
+      };
+
+      firstbootFile = mkOption {
+        type = types.str;
+        default = "/firstboot";
+        description = ''
+          Location of the file that allows commands to be run on first boot.
+          If overriding fileSystems."/" then you should to set this to the root mount + /firstboot
+        '';
+      };
+    };
+  };
+
+  config = let cfg = config.ps4; in lib.mkIf cfg.enable {
+    fileSystems = {
+      "/boot" = {
+        device = "/dev/disk/by-label/${cfg.usbImage.bootPartitionLabel}";
+        fsType = "vfat";
+        options = [ "nofail" "noauto" ];
+      };
+      "/" = {
+        device = "/dev/disk/by-label/${cfg.usbImage.rootPartitionLabel}";
+        fsType = "ext4";
+      };
+    };
+
+    boot.loader.grub.enable = lib.mkForce false;
+
+    # from https://github.com/NixOS/nixpkgs/blob/e405f30513169feedb64b5c25e7b00242010af58/nixos/modules/installer/sd-card/sd-image.nix#L267
+    boot.postBootCommands = let
+      expandOnBoot = lib.optionalString cfg.usbImage.expandOnBoot ''
+        # Figure out device names for the boot device and root filesystem.
+        rootPart=$(${pkgs.util-linux}/bin/findmnt -n -o SOURCE /)
+        bootDevice=$(lsblk -npo PKNAME $rootPart)
+        partNum=$(lsblk -npo MAJ:MIN $rootPart | ${pkgs.gawk}/bin/awk -F: '{print $2}')
+
+        # Resize the root partition and the filesystem to fit the disk
+        echo ",+," | sfdisk -N$partNum --no-reread $bootDevice
+        ${pkgs.parted}/bin/partprobe
+        ${pkgs.e2fsprogs}/bin/resize2fs $rootPart
+      '';
+      inherit (cfg.usbImage) firstbootFile;
+    in ''
+      # On the first boot do some maintenance tasks
+      if [ -f ${firstbootFile} ]; then
+        set -euo pipefail
+        set -x
+
+        ${expandOnBoot}
+
+        # TODO what does all this do?
+
+        # Register the contents of the initial Nix store
+        # ${config.nix.package.out}/bin/nix-store --load-db < ${firstbootFile}
+
+        # nixos-rebuild also requires a "system" profile and an /etc/NIXOS tag.
+        # touch /etc/NIXOS
+        ${config.nix.package.out}/bin/nix-env -p /nix/var/nix/profiles/system --set /run/current-system
+
+        # Prevents this from running on later boots.
+        rm -f ${firstbootFile}
+      fi
+    '';
+    
+    system.build.rootFileSystem = pkgs.callPackage (modulesPath + "/../lib/make-ext4-fs.nix") {
+      storePaths = [ config.system.build.toplevel ];
+      volumeLabel = cfg.usbImage.rootPartitionLabel;
+      populateImageCommands = ''
+        cp ${config.system.build.toplevel}/init ./files/init
+        touch ./files/firstboot
+      '';
+    };
+  };
+}