Is there any way to rescan or probe for devices after booting?

In particular I want to be able to show the bootverbose output for
bktr(4) without having to reboot again.

It seems like there must be a way -- or do the developers have to reboot
each time to check each code change?

Any documentation on this?

Thanks,

   Jeremy C. Reed
   http://bsd.reedmedia.net/