if called with --debopt "--arch=i386", grml-debootstrap installs a 32bit
userland with 64bit kernel.

# file root32/bin/bash
root32/bin/bash: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV),
dynamically linked (uses shared libs), for GNU/Linux 2.6.8, stripped

# ls root32/boot/vmlinuz*
root32/boot/vmlinuz-2.6.26-1-amd64

chroot root32
% dpkg --print-architecture
i386