Comment 82 for bug 477169

Here's what my grub-mkimage looks like (without the preamble)

prefix=
test_only=false

for option in "$@"; do
    case "$option" in
    --prefix=*)
        prefix=`echo "$option" | sed 's/--prefix=//'` ;;
    --test)
 test_only=: ;;
    esac
done

GRUB_DEVICE="`grub-probe --target=device /boot`"
case ${GRUB_DEVICE} in
  /dev/loop/*|/dev/loop[0-9])
    loop_file=`losetup ${GRUB_DEVICE} | sed -e "s/^[^(]*(\([^)]\+\)).*/\1/"`
  ;;
esac

# Is the root loop-mounted from a file on another filesystem?
if [ "x${loop_file}" = x ] || [ ! -f "${loop_file}" ]; then
  exit 1
fi

mtpt="${loop_file%/*}"
while [ -n "$mtpt" ]; do
    while read DEV MTPT FSTYPE OPTS REST; do
        if [ "$MTPT" = "$mtpt" ]; then
            loop_file=${loop_file#$MTPT}
            host_mountpoint=$MTPT
            break
        fi
    done < /proc/mounts
    mtpt="${mtpt%/*}"
    [ -z "$host_mountpoint" ] || break
done

if [ "x${host_mountpoint}" = x ]; then
    exit 1
fi

target="${host_mountpoint}/wubildr"

if [ ! -f "$target" ]; then
    exit 1
fi

if $test_only; then
    exit 0
fi

# TODO You might want to have this as a proper file somewhere in /usr/share
lupin_embedded_cfg=$(tempfile)
cat << EOF >> $lupin_embedded_cfg
set show_panic_message=true
if search -s -f -n $loop_file; then
    if loopback loop0 $loop_file; then
        set root=(loop0)
        if [ -e /grub/grub.cfg ]; then
            if configfile /grub/grub.cfg; then
                set show_panic_message=false
            fi
        fi
    fi
fi
if [ \${show_panic_message} = true ]; then
    echo "It is not possible to boot from the Ubuntu image."
    echo "The Windows partition might be corrupted."
    echo "Please reboot into Windows and run: chkdsk /r"
    echo "Then try again."
fi
EOF

# Watch the modules order!
modules=" \
    loadenv biosdisk part_msdos part_gpt fat ntfs ext2 ntfscomp iso9660 loopback \
    search linux boot minicmd cat cpuid chain halt help ls reboot \
    echo test configfile sh sleep"

grub-mkimage ${prefix:+--prefix="$prefix"} -c $lupin_embedded_cfg $modules | cat /usr/lib/grub/i386-pc/lnxboot.img - > "$target"
rm $lupin_embedded_cfg || true