Stephen Borrill said;

> A quick hacky work around is to duplicate the console/buffer logic from
aprint_normal
> to printf as below. If you want it completely silent, comment out the
lines in subr_autoconf.c
> that print "Detecting hardware", "done" and stick a return in twiddle()
(don't just force
> config_do_twiddle to 0 as this is logically mixed up with AB_QUIET mode in
config_attach()).
>
> ... twiddling flags bits in kernel printf() ...

I'm one of aprintf hater and I think this is far better.  It's a plain
mistake to
force every device driver changed to fit mis-designed feature.

Console message by kernel printf is sometimes rumbling for embed product
purpose.
I think it'd be fine to toggle the flags bit in runtime as will via
sysctl(3) interface,
not by boothowto variable which can be set once only at bootime.  I used to
practice
an MD cnputc() hack to suppress messages on demand.

Toru Nishimura/ALKYL Technology