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Date: Mon, 21 Jul 1997 16:34:50 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199707210634.QAA32661@godzilla.zeta.org.au>
To: ahd@kew.com, bde@zeta.org.au
Subject: Re: switching to seral consoles
Cc: current@FreeBSD.ORG
Sender: owner-freebsd-current@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

>> Actually, it is: boot with -hc, then wait for userconfig to start,
>> then type `flags sio0 0x10<return>q<return>' and reboot (switching
>> of consoles in userconfig currently only works for switching between
>> syscons and pcvt).
>
>How do you know when to reboot?  How do you know the machine didn't hang
>before rewriting the configuration out?

Perhaps by watching the disk LEDs.  Anyway, I lied,  Switching of consoles
in userconfig already works (after userconfig exits).

>more complicated sequence.  Why make it harder when the old way works
>properly?  What is the real world advantage of _requiring_ the flag in
>place of merely _supporting_ it?

The old way doesn't work properly.  The advantage of the flags are that
they let the user specify exactly which serial ports can be consoles
(flag 0x10), and which serial ports are consoles (flag 0x20 together with
flag 0x10).  You can have no consoles if you really want that (previously,
sio0 was always the console if syscons or pcvt was configured, provided
at least one sio port was configured, even if sio0 was not configured).
You can specify consoles on all sio ports if you really want that (but
this doesn't work yet).

>I don't have it in every kernel I gen for the same reason I don't put
>every possible device I have access to in the configuration for every
>machine (i.e. the machines have dissimilar hardware) -- I use the
>simplest configuration that works.

That configuration now has 0x10 in the flags for the serial port that
you want to use as the console (if you want to use a console at all).

Bruce