config strictly deactivates the drivers, it doesn't reduce memory
consumption or disk footprint.
WELL...there MIGHT be a small savings in data structures not allocated
for drivers, but that would most likely only be the case if you had such
a device in the machine, but deactivated the driver. (i.e., em(4) (the
driver) might allocate a RAM buffer for each em(4) card in the machine,
but only for the cards in the machine...disable the driver, you don't
allocate the buffers, but you can't use the card).
Since OpenBSD uses a monolithic kernel, it is outside the ability of
config to physically remove the deactivated drivers. That would be a
funky kind of relinking, or a bunch of loadable modules, ala Windows or
Linux, which is why Windows and Linux needs so much less RAM than
OpenBSD. Oh..wait... ;)
Removing drivers for reduced memory is really a "for advanced users
only" task, and you VERY QUICKLY run into diminishing returns. One
problem is you almost certainly need another computer -- if you have
16M RAM, you want to whittle down the kernel a lot...but $DEITY help
you if you need to build that new kernel on that machine, since just
sitting at the shell prompt will have you into swap. HOWEVER, by
the time you get to 32M, I doubt you will appreciate the time and
effort required to build and reboot off a new kernel (even if compiled
on another machine). You just won't be adding much functionality to
the machine -- there won't be something major you will suddenly be
able to do that you couldn't do before.
