Use tmpfs for /tmp + make ISO building work (?)

ISO/iso.nix

@@ -0,0 +1,8 @@
+{ lib, ... }:
+
+{
+  boot.supportedFilesystems = {
+    f2fs = true;
+    zfs = lib.mkForce false; # Pulled by ISO build for some reason, and it's broken as of writing
+  };
+}

configuration.nix

@@ -12,8 +12,8 @@
   To fix problems sometimes:
   sudo nixos-rebuild switch -I nixos-config=/etc/nixos/configuration.nix
 
-  To make an ISO:
-  sudo nixos-rebuild build-image
+  To make an ISO: (https://nixos.org/manual/nixos/stable/#sec-image-nixos-rebuild-build-image)
+  sudo nixos-rebuild build-image --image-variant iso-installer
 */
 let
   nixtamal = import ./tamal {
@@ -60,6 +60,9 @@ in
       ./modules/ccache.nix
       ./modules/networking.nix
       ./modules/mesa.nix
+
+      # ISO installer building stuff:
+      ./ISO/iso.nix
     ];
   
   home-manager.useUserPackages = true; # Puts user packages in /etc/profiles

modules/bootloader.nix

@@ -1,4 +1,4 @@
-{ pkgs, ... }:
+{ pkgs, lib, ... }:
 
 {
   catppuccin.plymouth.enable = false;
@@ -20,7 +20,7 @@
       # 0 = Hide the OS choice for bootloaders.
       # It would still be possible to open the bootloader list by pressing any key
       # It just would not appear on screen unless a key is pressed
-      timeout = 5;
+      timeout = lib.mkForce 5; # Forced, else it doesn't work when making an ISO
     };
 
     plymouth = {

modules/filesystems.nix

@@ -20,6 +20,10 @@
 
   services.fstrim.enable = true;
 
+  boot.tmp = {
+    useTmpfs = true; # I'll need to disable this or make it bigger if nix builds fail because of it
+  };
+
   # Link to nix-hardware configs in case I get a new laptop some day:
   # https://github.com/NixOS/nixos-hardware
 }