For the time being use $* for  this usecase.

One should be able to put all arguments passed to a function into a single (string) variable with all_arguments="$@". With grub-script currently, only the first argument will be stored in $all. I assume that this happens because of the way constructs like for arg in "$@" are supported, but it does not match bash semantics. Example script which gives different results in bash and grub-script:

function get_all_arguments {
  all_arguments="$@"
  echo "$all_arguments"
  echo "$@"
}

get_all_arguments "argument one" "argument two"