Changing makeoptions UKBD_DFLT_KEYMAP leads to kernel build fail

Hi,

I am trying to change the default keymap for my keyboard therefore I 
added the following options to my kernel configuration which leads to 
the error bellow.

Added options:

    options KBD_INSTALL_CDEV

    options UKBD_DFLT_KEYMAP

    makeoptions UKBD_DFLT_KEYMAP=de.iso


I tried it with this, too:

    makeoptions UKBD_DFLT_KEYMAP=german.iso


Both leads to the following problem:


    /usr/src/sys/dev/usb/input/ukbd.c:1209:18: error: use of undeclared identifier 'key_map'

             sc->sc_keymap = key_map;

                             ^

    /usr/src/sys/dev/usb/input/ukbd.c:1210:18: error: use of undeclared identifier 'accent_map'

             sc->sc_accmap = accent_map;

                             ^

    2 errors generated.

    *** Error code 1

Is there a dynamic way to change the keyboard layout at boot time to typ 
the zfs passphrase on my default keyboardlayout?

Regards,

Dominik