hardware-config.nix

{ config, lib, pkgs, ... }:
let
    rootfs = "/dev/disk/by-uuid/7165e542-0995-474c-a228-9592339e0604";
    swapfs = "/dev/disk/by-uuid/baaf824a-bee0-4037-a237-3a69f1db7985";

in
{
  # fs layout:
  # before: /nixos/nix/* /boot/grub/menu.lst
  # after:  /nix/* /old-root/boot/grub/menu.lst
  boot = {
    kernelPackages = pkgs.linuxPackages_latest;
    blacklistedKernelModules = ["coretemp"];
    # use grub 1, don't install
    loader.grub = {
      version = 1;
      enable = true;
      storePath = "/nixos/nix/store";
      extraPerEntryConfig = "root (hd0,0)"; # do we need this?
      mirroredBoots = [{
        path = "/old-root/boot";
        devices = ["nodev"];
      }];
      splashImage = null;
    };
    initrd.availableKernelModules = [ "xen_blkfront" ];
    kernelModules = [ ];
  	extraModulePackages = [ ];
  	kernelParams = ["root=${rootfs}" "boot.shell_on_fail"];
    initrd = {
      supportedFilesystems = [ "ext4" ];
      postDeviceCommands = ''
        mkdir -p /mnt-root/old-root ;
        mount -t ext4 ${rootfs} /mnt-root/old-root ;
      '';
    };
  };
  fileSystems = {
    "/" = {
      device = "/old-root/nixos";
      fsType = "none";
      options = [ "bind" ];
    };
    "/old-root" = {
      device = rootfs;
      fsType = "ext4";
    };
  };
  swapDevices = [ { device = swapfs; } ];
}