i386/100831: sio ignores BIOS information about serial ports - bounty offered

[Bruce Evans]

On Wed, 2 Aug 2006, Jo Rhett wrote:

> The following reply was made to PR i386/100831; it has been noted by GNATS.
>
> From: Jo Rhett <jrhett at svcolo.com>
> To: Bruce Evans <bde at zeta.org.au>
> Cc: freebsd-gnats-submit at freebsd.org, freebsd-i386 at freebsd.org,
>        njl at freebsd.org
> Subject: Re: i386/100831: sio ignores BIOS information about serial ports - bounty offered
> Date: Wed, 2 Aug 2006 14:47:01 -0700
>
> > >4. There should be no ill effect from doing this.  Console will never break
> > >and go to the wrong port.
> > >
> > >#4 is crucial to us.  Many of these machines are completely unavailable to
> > >me for an emergency.  This console is our "last chance access"
>
> On Thu, Aug 03, 2006 at 03:25:28AM +1000, Bruce Evans wrote:
> > Yes, "should be".  The wiring should be fairly deterministic once you
> > get it to work.  I think it will continue to work even if someone fixes
> > (?) ACPI to prefer the hints order to the ACPI order.  However, it would
> > break if someone fixes (?) ACPI to prefer the BIOS order to both the hints
> > order and the ACPI order (I think ACPI is using its own order and doesn't
> > know that you've swapped the order in the BIOS).
>
> Actually, it doesn't work right now.  I just tested it.
> /boot/device.hints: hint.sio.1.flags="0x90"
>
> If you change the flags in device hints, the low-level (boot loader 2?)
> console gets moved to wherever you put the flags.
>
> So now I have the exact reverse behavior.  The initialization part of the
> console goes to the wrong port, and then halfway through booting I
> suddently get console on the right port.

Everything is working as expected if you only changed the flags hint.
I said that the port hint must be changed too.

> I think I have to agree with Marcel on this -- device hints aren't used
> consistently, and having two different processes read it with two
> completely different interpretations of it is nonsense.  I can't fix one
> without breaking the other.

Just avoid inconsistencies by making all the hints match the unit number
assignments that you get although these are not the unit number assignments
that you want.

Bruce