make-kpkg --- error in 2.4.18 in char.o undefined reference to 'register_serial'

["Dale Welch" <mlist@babbler.org>]

I got the source for 2.4.18.
Used make-kpkg
after trying to answer many many questions :-) ...
i got the following error:
   drivers/char/char.o(.text+0x142d5): undefined reference to
'register_serial'

this is defined in a couple different forms of serial.c

Any idea what is wrong... do i just add somewhere for it to link serial.o or
is it in one of the other serial*.c files?

thanks,

dale welch