Subject: Re: serial console and spurious breaks
To: Emmanuel Dreyfus <manu@netbsd.org>
From: Greg A. Woods <woods@planix.com>
List: netbsd-users
Date: 07/23/2007 12:33:28
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At Mon, 23 Jul 2007 15:05:27 +0000, Emmanuel Dreyfus wrote:
Subject: Re: serial console and spurious breaks
>=20
> On Mon, Jul 23, 2007 at 10:07:54AM -0400, Steven M. Bellovin wrote:
> > > break is really useful, but unplanned server downtime just because a
> > > serial cable was unplugged is a shame.
> >=20
> > Set ddb.fromconsole=3D0 in sysctl.conf.
>=20
> I'd like to retain the ability to drop into ddb from the console, I just
> want to avound getting there if I unplug the cable.

It is also possible to build a simple circuit to "protect" the signaling
lines of your serial port such that noise or surges won't as likely be
seen as a BREAK signal whenever the port is disconnected.  One could
even argue that the port's line drivers should have such protection
built in!  :-) 

	http://www.cisco.com/warp/public/770/fn-tsbreak.html

	http://mail-index.netbsd.org/port-sparc/2002/05/16/0000.html

--=20
						Greg A. Woods

H:+1 416 218-0098 W:+1 416 489-5852 x122 VE3TCP RoboHack <woods@robohack.ca>
Planix, Inc. <woods@planix.com>       Secrets of the Weird <woods@weird.com>

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