[ On Wednesday, January 5, 2005 at 11:12:25 (+0000), Michael Smith wrote: ]
> Subject: Re: 2.0 on DEC3000 drops to debugger if console is not connected (resend)
>
> Perhaps there are two problems here: faulty hardware in the DEC box
> and a new vulnerable driver for the console device.

If the system gets past starting /sbin/init then it's almost impossible
that it's any device driver related software problem.

The most logical explanation for the behaviour of 1.6 is likely that it
was not functioning correctly.

> > Don't disconnect a serial console during operation!  :-)
> 
> Yes, though where I work we have probably a hundred DS10's running
> Tru64. If you want to work on a machine you plug a flying console
> cable into it, shut it down, start it up, check that it is ok and then
> pull the cable out. Halting at that point would be a bit sub-optimal.

That's a highly unreliable way of doing things.  It's extremely easy to
generate a signal electrically indistinguishable from a BREAK when
connecting and disconnecting almost any kind of cable.

I'm extremely surprised that you have not yet experienced any problems
when moving that cable around.  Perhaps the DS10 has an RMC (I think it
does), and so like all the other Alpha machines with a Remote Management
Console it doesn't ever see any BREAK signals from the extermal serial
port because of the way the RMC serial port interfaces the external
connector to the internal COM1 port.  At least I've never been able to
convince the RMC controller to pass any BREAK signal into the internal
COM1 port so that it's seen on the NetBSD console port.

I'm pretty sure though that the 3000 doesn't have an RMC controller so
its COM1 port will see any generated BREAK signal directly (as it should).

If the DS10's have no RMC then there is a relatively simple circuit that
can be built into a gender changer or adapter plug and used to ensure
that no BREAK signal, noise related or otherwise, is ever seen by the
system, but since you'd need one permanently connected to every system,
I think you'd be much better off to get a cheap used terminal server or
three and hook up all those systems to permanent console ports.  Note
too that permanent console port connections, plus helpful software such
as conserver (in pkgsrc), makes it possible to "remotely" manage all the
machines "simultaneously" without ever having to move any cables around.
Used 30-port or so terminal servers can be had these days on the used
equipment market (e.g. eBay) for a tiny fraction of their original cost.

-- 
						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>