SUMMARY: Strange problem at Boot time/Single user mode

From: Paul Alukal (
Date: Fri Jul 08 1994 - 01:56:43 CDT

My original message:

>Hello Sun-Managers,
>I am experiencing this strange problem when booting or trying to
>become single user mode (or boot -s).
>The system is a Sparc server 4/690, with SunOS 4.1.3. It was working
>fine, till a power outage crashed the system, and caused the main power
>supply on the back of the main cabinet and on the differential SCSI
>disks where the boot disk is located, to go bad (sd4: <SUN2.1G cyl 2733
>alt 2 hd 19 sec 80>).
>We had both power supplies replaced by Sun Hardware support. The
>system came back in multiuser mode, however the following error message
>was detected at boot time.
>At boot time, on the vt220 console, I get all messages clear, except
>when it starts to say ifconfig.
>Example: (reboot)
>messages ----
>swap on ----- (clear up to this point)
> ^From this point, I get strange characters (not the +), and it goes
>to the right end of the screen and stops there, no carriage returns,
>and we can not see anything, till it comes to give the 'login' prompt
>(multiuser mode).
>If I shutdown the system to single user mode, the prompt becomes
>strange characters to read, (and then unable to see what is going on
>after each command). "boot -s" is also comes to same problem.
>In short, any time I boot (or reboot) the system, at the same point
>where it starts 'ifconfig", the characters get mangled, and no carriage
>return till I get the boot prompt.
>I put a command in the /etc/rc.local file to capture all startup
>messages to a log file. However, I would like to clear this problem,
>and also would like to get into single user mode.
>I suspect whether any specific file got corrupted during power
>outage/crash. I have reconfigured kernel, but that did not clear this
>Any help or suggestions to fix this will be appreciated.
>Thank you.
>Paul V. Alukal e-mail:
>GMI Eng. & Mgmt. Institute, Computer Center Telephone: (810) 762-7964
>1700 West Third Avenue, Flint, MI 48504 Facsimile: (810) 762-9819

Thank you very much for this group. The problem is almost solved.
One thing I missed in my post was to say that the cpu board was
also replaced by sun hardware support.

All of the mail messages suggested problem could be about parity, and
suggested to change settings from 8 bit, no parity to 7 bit, even. The
mail from (Ken Weiss) was the most useful. It is
included here.

Unfortunately, SUN Software support could not come up with any
suggestion. Once I got replies from this group, I conveyed it to Sun
Software Support - the person I talked to claim there is nothing
similar this in their database, and as usual try to avoid looking into
this any further!

Thanks to:

Matthew North <> (Glenn Satchell - Uniq Professional Services)
"Reggie Beavers" <vjq09r4@shoes.Bell-Atl.Com> (Russ Poffenberger) (Ken Weiss)
From: (Ken Weiss)

I had a simular problem and had to do 2 things:

:at boot time, on the vt220 console, I get all messages clear, except
:when it starts to say ifconfig.

>From : Sunsolve ----
 Bug Id: 1098303
 Category: kernel
 Subcategory: other
 Release summary: 4.1.2
 Synopsis: garbled screen when booting munix from a tty console -
        stty settings change
 Integrated in releases:
 Patch id:

Booting munix on a 4/6xx machine with a vt100 connected as the console
prevents munix from booting. The problem is with the terminal
characteristics. Normally we set them to 8 data bits, 1 stop bit, no
partity. If the terminal is set up with these characteristics prior to
the boot, the screen will become garbled 1/2 way through the boot
process. And it will be unable to continue until the terminal
characteristics are changed to 7 data, 1 stop and even parity.

The workaround is to change the characteristics to 7 data bits, 1 stop
bit and even partity when the screen becomes garbled. Then continue
with the munix boot.

Also we had to add stty settings in the /etc/rc file as follows:

#! /bin/sh -
# @(#)rc 1.45 90/08/08 SMI; from UCB 4.3
# The rc sh gets the console. All commands are by
# default protected from tty signals (i.e. are not interruptable).
# Interrupts can be enabled by proceeding any command line with "intr".
# Console redirection is no longer needed.
# Make sure PATH is exported or intr won't find what it needs.
stty pass8
HOME=/; export HOME
PATH=/bin:/usr/bin:/usr/etc; export PATH

*****the line***** stty pass8 *****above is the thing to add

This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:09:05 CDT