we're about to operate on, try to load one. Don't complain if the
load fails, and always press on regardless (there may not be a module
suitable or required).
With the renaming of the PCI ethernet driver modules and the addition
of appropriate miibus dependancies on those modules that need it, it is
now no longer necessary to compile many ethernet drivers into the kernel;
they will be loaded on demand the first time they are ifconfig'ed.
Inspiration from: mount
Reviewed by: obrien
4d16916f80