repro.nix

{ pkgs ? import <nixpkgs> {}}:
let inherit (pkgs) stdenv utillnux;
in
stdenv.mkDerivation {
  name = "efi";
  nativeBuildInputs = [
    utillinux
  ];
  buildCommand = ''
reserved=4096
espSize=14944
rootSize=71176
veritySize=576
fullSize=$(($reserved + $espSize + $rootSize + $veritySize))
echo $fullSize
truncate --size $(( $fullSize * 512 )) out.img

sfdisk out.img <<EOF
label: gpt
size=$espSize
size=$rootSize
size=$veritySize
EOF
cp out.img $out

  '';
}