Booting from the netboot
 media (PXE)
  Advanced users may wish to install NixOS using an existing PXE or
  iPXE setup.
  These instructions assume that you have an existing PXE or iPXE
  infrastructure and simply want to add the NixOS installer as another
  option. To build the necessary files from a recent version of
  nixpkgs, you can run:
nix-build -A netboot nixos/release.nix
  This will create a result directory containing: *
  bzImage – the Linux kernel *
  initrd – the initrd file *
  netboot.ipxe – an example ipxe script
  demonstrating the appropriate kernel command line arguments for this
  image
  If you’re using plain PXE, configure your boot loader to use the
  bzImage and initrd files and
  have it provide the same kernel command line arguments found in
  netboot.ipxe.
  If you’re using iPXE, depending on how your HTTP/FTP/etc. server is
  configured you may be able to use netboot.ipxe
  unmodified, or you may need to update the paths to the files to
  match your server’s directory layout
  In the future we may begin making these files available as build
  products from hydra at which point we will update this documentation
  with instructions on how to obtain them either for placing on a
  dedicated TFTP server or to boot them directly over the internet.