>телепаты традиционно в отпуске.
А жаль :)
>для начала бы хотелось увидеть dmesg после insmod,
insmod serial.o выдаёт:

serial.o: unresolved symbol test_and_clear_bit
serial.o: unresolved symbol strcat
serial.o: unresolved symbol get_free_page
serial.o: unresolved symbol inb
serial.o: unresolved symbol __put_user_X
serial.o: unresolved symbol __get_user_X
serial.o: unresolved symbol run_task_queue
serial.o: unresolved symbol remove_wait_queue
serial.o: unresolved symbol __constant_memcpy
serial.o: unresolved symbol __constant_c_memset
serial.o: unresolved symbol queue_task
serial.o: unresolved symbol down
serial.o: unresolved symbol remove_bh
serial.o: unresolved symbol __memcpy
serial.o: unresolved symbol init_bh
serial.o: unresolved symbol mark_bh
serial.o: unresolved symbol add_wait_queue
serial.o: unresolved symbol signal_pending
serial.o: unresolved symbol up
serial.o: unresolved symbol __constant_c_and_count_memset
serial.o: unresolved symbol __constant_test_bit
serial.o: unresolved symbol capable
serial.o: unresolved symbol set_bit
serial.o: unresolved symbol clear_bit
serial.o: unresolved symbol outb
serial.o: unresolved symbol __test_bit
serial.o: unresolved symbol __memset_generic

>uname -a на таргете

MCBC <имя компа> 2.2.20-MCBC #1 <дата> i686 unknown

> и узнать способ сборки модуля.
Привожу  Makefile:

CC = gcc
MODFLAGS := -Wall -DMODULE -D__KERNEL__ -DLINUX -I/usr/src/linux/include/
serial.o : serial.c /usr/src/linux/include/linux/version.h
    $(CC) $(MODFLAGS) -c serial.c