SUMARY:Send Break to the tty ports at sh

Date: Wed Oct 22 1997 - 08:12:52 CDT

Thankx for all who asnwered to my question

Original Question

I'm using a Sun Sparc 4 as console of two servers (without keyboard and
monitor) through the tty ports.
When I need to shutdown this SS4, it sends a Break signal to the tty
ports and the two servers goes into the boot promm.

The simplest solution to avoid this to happen was to disconnect the
serial cable from de SS4 before rebooting it, and then connect it again.

1) Are this Break signal sent at shutdown to the tty ports driving by a

 scripts in /etc/rcx.d or is a hardware signal that is always sent when a

 machine goes down ?

2) There are some way to configure the SS4 for not send the break signal

 to the tty ports at shutdown ?


1) It doesn't actually send a break - the chip is reset, which generates
garbage, which the other side interprets as a break...because a break
signal is a long absence of a signal on the serial port

2) There are three solutions but I have not time for test anyone :

a - to buy keyboards for the other hosts - they
 aren't very expensive, and you can individually control what
 you send each system.

b - to keep the tx line high by wiring up the ports on the servers
 I'm using a cable with local loops in 4-5 and 6-8-20 pines.
 (thus I'm only using Tx, Rx and Grd signals between the console and the
  I tryed to pull-down the Rx line in the servers but the problem stil

c - to make the other systems ignore breaks by
 NOPing out the call to debug_enter() in the zs driver.

Sorry for the delay. Bye

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