This will keep configuration configuring the size of the /boot partition still build, while showing the deprecation warning. In 99.9% of cases I assume ignoring the configuration is better, as the sd-image builder already is pretty opinionated in that matter.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.