SUMMARY: Power down Terminal-Server causes BREAK

Date: Thu Jul 31 1997 - 09:13:39 CDT

Hi Sun Managers,

great response to our question! The solution is to turn the front panel key
on the E3000s to the 'locked' position.

>> the original question was:

>We have connected the serial ports of some E3000 Solaris 2.5.1 systems to a
>CHASE IOLAN Terminal-Server and can connect to each CONSOLE via Telnet.
>Everything works fine, until the Terminal-Server is powered down and all
>systems are halted and going to the OK-Prompt.
>We have tried several things like attaching an 4.7k resistor between pins 25
>(24) and 3 on the serial Port, activating hardware-handshake and so on but
>nothing prevents from halting the systems.
>Now we are looking for a way to disable the Break/Stop-A detection on a
>serial Port CONSOLE. SunSolve also mentions that a 'secure' environment
>requires Stop-A to be disabeled, but tells us nowhere how to do this.

>> thanks to everyone who answered:

Casper Dik <casper@holland.Sun.COM>:

Solaris 2.6 has this feature; but in 2.5.1 and before there's no way to
disable break/L1-A (Ron Spillane):

The 'secure' environment sunsolve is talking about is the power key on the
front panel of the E3000, once you boot your system up turn that clockwise to
'lock' position (the last position) and your system should not shutdown when
the console connection is broken.

This works on the E1000 and E4000 we have here. (Niall O Broin):

This really does have to get put in the FAQ. Search the archives, as it's been
answered before. Sun's official way of doing it is with a product called
Z-Consult or somesuch which makes an alternative key sequence from the
terminal drop into monitor mode (the default behaviour is that a break on a
serial console has the same effect as Stop-A on a Sun keyboard, and the
problem arise because many terminals send break signals deliberately on
powerup, and also the crap which can appear on the signal lines during powerup
is likely to be interpreted as a break signal.

Another option is to modify the console driver so as to have it ignore the
BREAK - I believe Kevin Sheehan, a regular on this list, has done this.

Dave Blackman <>:

I think that one of the front panel key positions disables the terminal break.

Gerald Combs - Unicom Communications <>:

Does the terminal server stay down very long? If not, you might try
configuring the greeting message to send the string "ok<return>" to each port on
startup. It's a cheesy solution, but we had a similar situation here, and it
was the only one that worked.

Seth Rothenberg <>:

This is a secret I learned from Qualix,
who sold us qHA High Availability. It applies to SC1000, and possibly other

If you put the key in the LOCK position, unplugging the keyboard or pressing
Stop-A or BREAK will NOT affect the system.

Careful, there is a Diagnostic position on the 1000E and it is not a RUN state. (Brian K. Stolp):

We experienced the same thing with other products as well particularly sparc 5's
what we finally were able to come up with is a change of product to cisco 2500
or 2510's. we don't have that problem anymore. we alos are able to connect
modems to the cisco's forconsole dial-in. great product great results and

Not to sound condescending, but try turning the key on the server to the locked
possition. This will enable you to power of the terminal and not drop to the ok
prompt. And will also prevent the stop-a from working. (Greg Price):

The trick with the resistor only works on the older systems, definitely not the
ultra's. Essentially they removed the +5v power source from pin 25. You may want
to consuslt your field engineer about using an external +5v supply, you should
also talk to Sun about a couple of "consulting specials" which address the
issue. Another alternative is the rebadged and modified Xylogics terminal server
which Sun sells (and is dropping from the pricelist I think). It has been
modified to avoid the side effects you mention. Disabling Stop-A/ Break was
never acceptable to me, but may be ok for you. I don't know what the secure mode
is mentioned in your post, but if you are into patching kernels there are ways
of doing it.

Look for a 4 position keyswitch in the front of box. Turn key fully clockwise to
the SECURE position.

I read your request on sun-managers list. We have similar problems with wyse
consoles being turned off causing systems to go to the boot prompt. You
mentioned attaching a 4.7K ohm resistor from pin 3 to pin 24 of the serial
connector... is there a reference document that you could refer me to regarding
this modification?

---> see SunSolve infodoc 2115 (Kevin Sheehan):

I make the first instruction of "debug_enter" a return instruction, which is the
routine (generally - it can vary by architecture) that is called for break and
L1-A stuff to get to the prom or debugger.

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