trouble building 'ndis' device driver into stripped-down custom kernel.

[Robert Bonomi]

Enviorment is FreeBSD 8.3,  i386

I'm currently running a stipped-down custom kernal with all superfluous 
devices/options removed.

I'm trying to add the 'ndis' device back in, but when I follow the directions
on the ndis(4) manpage, and add:
    options NDISAPI
    device  ndis
and try to re-compile the kernel (config, cd, make depend, make), linking 
fails, with:
    if_ndis.o(.text+0x1104): In function 'ndis_detach':
    : undefined reference to 'ndis_free_amem'
    if_ndis.o(.text+0x1194): In function 'ndis_attach':
    : undefined reference to 'ndis_alloc_amem'

Obviously, the config file is missing 'something'  -- does anybody have
any ideat _what_ that something is?