2c1cf879a0
This allows to perform `dd if= of=$img` after the image is built which is handy to add e.g. uBoot SPL to the built image. Instructions for some ARM boards sometimes contain this step that needs to be performed manually, with this patch it can be part of the nix file used to built the image.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at https://nixos.org/nixos and in the manual in doc/manual.