Last time I used lkm, it had a real major problem.  modload lets you 
link the module that you are loading against any kernel (-A).  But
if I load modules out of /etc/rc, I have to chose some particular
kernel, usually /netbsd.  So if I happen to boot /netbsd.foo when
/etc/rc goes to modload my lkm (say afs), I die a horrible death.

It seems to me that the first thing to do to improve lkm, is to make
the kernel export a subset of its symbols.  This solves the above
problem and also makes the interface that an lkm uses more controlled,
it is only what the kernel explicitly exports.

Linux worked this way last time I looked at it.