diff --git a/pr-28.patch b/pr-28.patch
index 0ca9a47..b47b3b3 100644
--- a/pr-28.patch
+++ b/pr-28.patch
@@ -49,29 +49,61 @@ index 331fecd..85fda30 100644
      system.build.extraUtils = extraUtils;
      boot.initrd.availableKernelModules = [ ];
      boot.initrd.kernelModules = [ "tun" "loop" "squashfs" ] ++ (lib.optional config.not-os.nix "overlay");
+diff --git a/stage-2-init.sh b/stage-2-init.sh
+index 6cc08e2..0c854c4 100644
+--- a/stage-2-init.sh
++++ b/stage-2-init.sh
+@@ -19,4 +19,7 @@ mount -t tmpfs tmpfs /dev/shm
+ 
+ $systemConfig/activate
+ 
++# Run any user-specified commands.
++@runtimeShell@ @postBootCommands@
++
+ exec runit
 diff --git a/stage-2.nix b/stage-2.nix
-index c61f9d6..4e30d4b 100644
+index c61f9d6..46cf260 100644
 --- a/stage-2.nix
 +++ b/stage-2.nix
-@@ -21,6 +21,11 @@ with lib;
+@@ -20,6 +20,19 @@ with lib;
+         example = "256m";
          type = types.str;
         };
-     };
++      postBootCommands = mkOption {
++        default = "";
++        example = "rm -f /var/log/messages";
++        type = types.lines;
++        description = lib.mdDoc ''
++          Shell commands to be executed just before runnit is started.
++        '';
++      };
++    };
 +    networking.hostName = mkOption {
 +      default = "";
 +      type = types.strMatching
 +        "^$|^[[:alnum:]]([[:alnum:]_-]{0,61}[[:alnum:]])?$";
-+    };
+     };
    };
    config = {
-     system.build.bootStage2 = pkgs.substituteAll {
+@@ -28,6 +41,9 @@ with lib;
+       isExecutable = true;
+       path = config.system.path;
+       inherit (pkgs) runtimeShell;
++      postBootCommands = pkgs.writeText "local-cmds" ''
++        ${config.boot.postBootCommands}
++      '';
+     };
+   };
+ }
 diff --git a/zynq_image.nix b/zynq_image.nix
-index 3fa23ab..695d876 100644
+index 3fa23ab..06dd1a5 100644
 --- a/zynq_image.nix
 +++ b/zynq_image.nix
-@@ -1,66 +1,63 @@
- { config, pkgs, ... }:
+@@ -1,66 +1,90 @@
+-{ config, pkgs, ... }:
++{ lib, config, pkgs, ... }:
  
++with lib;
  let
 -  # dont use overlays for the qemu, it causes a lot of wasted time on recompiles
 -  x86pkgs = import pkgs.path { system = "x86_64-linux"; };
@@ -154,17 +186,15 @@ index 3fa23ab..695d876 100644
 -    chmod +x qemu-script
 -    patchShebangs qemu-script
 -    ls -ltrh
--  '';
+   '';
 -  system.build.rpi_image_tar = pkgs.runCommand "dist.tar" {} ''
 -    mkdir -p $out/nix-support
 -    tar -cvf $out/dist.tar ${config.system.build.rpi_image}
 -    echo "file binary-dist $out/dist.tar" >> $out/nix-support/hydra-build-products
-   '';
+-  '';
 -  environment.systemPackages = [ pkgs.strace ];
 -  environment.etc."service/getty/run".source = pkgs.writeShellScript "getty" ''
 -    agetty ttyPS0 115200
--  '';
--  environment.etc."pam.d/other".text = "";
 +  environment = {
 +    systemPackages = with pkgs; [ strace inetutils ];
 +    etc = {
@@ -181,4 +211,31 @@ index 3fa23ab..695d876 100644
 +      "security/pam_env.conf".text = "";
 +    };
 +  };
++  boot.postBootCommands = lib.mkIf config.not-os.sd ''
++    # On the first boot do some maintenance tasks
++    if [ -f /nix-path-registration ]; then
++      set -euo pipefail
++      set -x
++      # Figure out device names for the boot device and root filesystem.
++      rootPart=$(${pkgs.utillinux}/bin/findmnt -n -o SOURCE /)
++      bootDevice=$(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
++
++      # Register the contents of the initial Nix store
++      nix-store --load-db < /nix-path-registration
++
++      # nixos-rebuild also requires a "system" profile and an /etc/NIXOS tag.
++      touch /etc/NIXOS
++      nix-env -p /nix/var/nix/profiles/system --set /run/current-system
++
++      # Prevents this from running on later boots.
++      rm -f /nix-path-registration
++    fi
+   '';
+-  environment.etc."pam.d/other".text = "";
  }