I was wondering why the build creates a libkern.o (so all the objects
   are included in every kernel) rather than a libkern.a so that only the
   referenced items are included?
   
   My suspicions have to do with ensuring that LKMs have all the functions
   available...

that is right.
   
   OTOH the install kernel will fit if built with a libkern.a ...
   Although cutting down on sysctl would also help.
   
   I also have half a plan to police the size of the small kernels, using
   a script that will report the guilty party when it all stops fitting.

LKM-unaware kernels could use libkern.a i believe...


.mrg