Adding a driver

[Brad Murray <bjm_(_at_)_phreeow_(_dot_)_net>]

I want to add SMC 91Cxxx ISA support to my kernel.  This chipset is
already supported under PCI in the GENERIC kernel config.  ISA drivers
exist in sys/dev/isa though.  Also, the files.isa entry for them
appears correct.  So I added the following line to my kernel config
file:

  sm1     at isa? port 0x340 irq 10

However, when I build the kernel I get the following error rather far
along in the process:

  ld -z -Ttext E0100000 -e start -x -o bsd ${SYSTEM_OBJ} vers.o
  if_sm_isa.o: Undefined symbol `_smc91cxx_idstrs' referenced from text segment
  *** Error code 1

  Stop in /usr/src/sys/arch/i386/compile/SEKRIT (line 481 of Makefile).

Now I note that this symbol is defined in sys/dev/ic/smc91cxxx.c but
that this is never built.

What am I doing wrong and what do I need to read in order to avoid
doing it wrong in the future?  Thanks.
 
-- 
Brad Murray    * Always carry a short length of fibre-optic cable. If
Perl Geek      * you get lost, then you can drop it on the ground, wait
VSCA Founder   * ten minutes, and ask the backhoe operator how to get
Magnet Oper    * back to civilization.                     (Alan Frame)