i think it makes sense to have 3 levels:

	- quiet (see pr kern/5155)
	- normal (running about one or two lines per driver instance,
		roughly equivalent to current behavior, 
		and the default default value)
	- verbose (spewing more detail).

with boot flags to select each, and a default value specifiable in
boot blocks and/or kernel config file.

the rationale for "quiet" is simple:

certain embedded applications of netbsd might not want to throttle
kernel initialization based on how quickly they can spew out a 9600
baud serial console; others might not want to baffle users with the
spewage.  

RB_QUIET, RB_VERBOSE, ...

					- Bill