Add custom kernel config to shrink the image size

base.nix

@@ -1,15 +0,0 @@
-{ ... }:
-{
-  imports = [
-    ./modules/filesystems.nix
-    ./modules/generic.nix
-    ./modules/kernel.nix
-    ./modules/minimize.nix
-    ./modules/network.nix
-    ./modules/patagia-agent.nix
-    ./modules/partitions.nix
-    ./modules/system_overrides.nix
-    ./modules/sysupdate.nix
-    ./modules/utils.nix
-  ];
-}

flake.nix

@@ -107,8 +107,16 @@
                   inherit patagia-agent;
                 };
               }
-              ./base.nix
+              ./modules/kernel
+              ./modules/filesystems.nix
+              ./modules/generic.nix
+              ./modules/minimize.nix
+              ./modules/network.nix
               # ./modules/patagia-agent.nix
+              ./modules/partitions.nix
+              ./modules/system_overrides.nix
+              ./modules/sysupdate.nix
+              ./modules/utils.nix
             ];
           };
         };

modules/generic.nix

@@ -11,7 +11,6 @@
     initrd.systemd.enable = true;
     kernelParams = [
       "console=ttyS0"
-      # "quiet"
     ];
     loader.efi.canTouchEfiVariables = true;
     loader.grub.enable = false;
@@ -19,18 +18,7 @@
     uki.name = "patos";
   };
 
-  # Temporary files
-  boot.tmp.useTmpfs = true;
-  systemd.services.nix-daemon = {
-    environment.TMPDIR = "/var/tmp";
-  };
-
-  system.switch = {
-    enable = false;
-    enableNg = true;
-  };
-
-  services.fstrim.enable = true;
+  system.image.version = "0.0.1"; # FIXME: Use epoch version.
 
   system.nixos = {
     codeName = "Finn";
@@ -39,7 +27,7 @@
     release = "2024-09";
   };
 
-  system.image.version = "0.0.1"; # FIXME: Use epoch version.
+  system.switch.enable = false;
 
   # Make the current system version visible in the prompt.
   programs.bash.promptInit = ''
@@ -51,15 +39,21 @@
 
   services.getty.autologinUser = "root";
 
-  # Don't accumulate crap.
+  # Temporary files
   boot.tmp.cleanOnBoot = true;
+  boot.tmp.useTmpfs = true;
+  systemd.services.nix-daemon = {
+    environment.TMPDIR = "/var/tmp";
+  };
+
   services.journald.extraConfig = ''
     SystemMaxUse=10M
   '';
 
+  services.fstrim.enable = true;
+
   # Debugging
   environment.systemPackages = with pkgs; [
-    parted
     (runCommand "systemd-sysupdate" { } ''
       mkdir -p $out/bin
       ln -s ${config.systemd.package}/lib/systemd/systemd-sysupdate $out/bin

modules/kernel.nix

@@ -1,13 +0,0 @@
-{ pkgs, ... }:
-{
-  boot.kernelPackages = pkgs.linuxPackages_6_11;
-  boot.kernelPatches = [
-    {
-      # name = "crashdump-config";
-      patch = null;
-      extraConfig = ''
-        EROFS_FS_ZIP_ZSTD y
-      '';
-    }
-  ];
-}

modules/kernel/default.nix

@@ -0,0 +1,19 @@
+{ lib, pkgs, ... }:
+{
+  boot.kernelPackages =
+    let
+      version = "6.11.2";
+    in
+    pkgs.linuxPackagesFor (
+      pkgs.linuxManualConfig {
+        version = "${version}-patos1";
+        modDirVersion = version;
+        src = pkgs.fetchurl {
+          url = "https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-${version}.tar.xz";
+          hash = "sha256:ec9ef7a0b9cebb55940e1ef87a1f9e1004b10456a119dc386bb3e565b0d39c42";
+        };
+        configfile = ./generic.config;
+        allowImportFromDerivation = true;
+      }
+    );
+}

modules/minimize.nix

@@ -5,12 +5,13 @@
   ];
 
   nix.enable = false;
-
+  system.disableInstallerTools = true;
   system.etc.overlay.enable = true;
+
   systemd.sysusers.enable = true;
 
-  system.disableInstallerTools = true;
   programs.less.lessopen = null;
   programs.command-not-found.enable = false;
+
   environment.defaultPackages = [ ];
 }

modules/partitions.nix

@@ -21,7 +21,7 @@
 
       mkfsOptions = {
         erofs = [
-          "-zzstd,5" # Zstd compression
+          "-zzstd,6" # Zstd compression
           "-T0" # Fixed timestamp for all files
           "-Efragments,dedupe,ztailpacking" # Extended options
         ];
@@ -31,7 +31,6 @@
         "esp" = {
           contents = {
             "/EFI/BOOT/BOOT${lib.toUpper efiArch}.EFI".source = "${pkgs.systemd}/lib/systemd/boot/efi/systemd-boot${efiArch}.efi";
-
             "/EFI/Linux/${config.system.boot.loader.ukiFile}".source = "${config.system.build.uki}/${config.system.boot.loader.ukiFile}";
 
             # systemd-boot configuration
@@ -59,7 +58,6 @@
             Format = "erofs";
             Minimize = "best";
             ReadOnly = "yes";
-
             SizeMinBytes = "1G";
             SizeMaxBytes = "1G";
             SplitName = "store";

overlays/default.nix

@@ -1,4 +1,5 @@
 final: prev: {
+  # Build mkfs.erofs with zstd support
   erofs-utils = prev.erofs-utils.overrideAttrs (old: {
     buildInputs = old.buildInputs ++ [ prev.zstd ];
     configureFlags = old.configureFlags ++ [