enforce-arch.nix

{ stdenv, makeSetupHook }:

let
  target = if builtins.trace "system is ${stdenv.system}" stdenv.system == "armv6l-linux" then "Tag_CPU_arch: v6" else
    (if stdenv.system == "armv7l-linux" then "Tag_CPU_arch: v7" else "NOP");
in
if target == "NOP" then
    makeSetupHook {} ./nop.sh
else
    makeSetupHook { substitutions = { inherit target; NIX_DEBUG="1"; }; } ./enforce-arch.sh

enforce-arch.sh

function enforceArch() {
  echo checking target arches
  for x in $out/lib/*.so; do
    echo checking $x
    readelf -A $x | grep "@target@"
  done
}
postInstallHooks+=(enforceArch)