boot0sio working for anyone?

David Wolfskill david at
Sat Feb 9 14:10:42 UTC 2008

On Sat, Feb 09, 2008 at 02:17:06PM +0100, Ulrich Spoerlein wrote:
> On Feb 9, 2008 12:43 PM, Dag-Erling Smørgrav <des at> wrote:
> > Ulrich Spoerlein <uspoerlein at> writes:
> > > So, to recap the question: Is boot0sio working with 9600 or 115200 baud
> > > for anyone on 8-CURRENT (and built with gcc 4.x)?
> >
> > I use the regular boot0, and
> >
> > console="comconsole"
> > comconsole_speed="115200"
> >
> > in /boot/loader.conf
> Can you boot from different disks and slices using this approach?
> Perhaps with this weird syntax?
> 0:ad(0,a)/boot/loader
> Or can the loader be tricked into chain-booting another loader on
> another disk and slice? (Lucky me, I'm only trying to get this to work
> using FreeBSD only ...)

I'm a bit hesitant to chime in, as my approach appears to differ both in
means and ends from yours, but perhaps the ends aren't all that
different after all, and it might help, so:

For my "build machine," which I run headless, I also use the regular
boot0.  However, my /boot/loader.conf is empty.

Rather, I created /boot.config; it contains


and  I have its sio0 connected to one of the serial ports of the
nearest other machine (a SPARCstation 5/170) via a "null MODEM" cable.

I also configured the BIOS to use "serial redirection" (so I have access
to poke at BIOS stuff when I'm physically distant form the machine) --
though that doesn't matter for boot disk/slice selection.

I'm using the FreeBSD boot loader; hitting F[1-5] when the FreeBSD boot
loader prompts does the usual disk & slice selection, though I only use
that ability when I've forgotten to set the next boot slice via

(In my case, I do this because I track each of RELENG_6, RELENG_7, and
HEAD on different slices of the boot disk on the machine.)

David H. Wolfskill				david at
I submit that "conspiracy" would be an appropriate collective noun for cats.

See for my public key.
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