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Date:      Thu, 10 Jun 1999 17:34:32 +1000
From:      Phil Homewood <philh@mincom.com>
To:        freebsd-current@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG
Subject:   Re: ENABLE_SERIAL_BREAK_KEY...or something?
Message-ID:  <19990610173432.K29796@mincom.com>
In-Reply-To: <Pine.LNX.4.05.9906100216360.10213-100000@jason.argos.org>; from Mike Nowlin on Thu, Jun 10, 1999 at 02:27:30AM -0400
References:  <19990610154124.F22693@mincom.com> <Pine.LNX.4.05.9906100216360.10213-100000@jason.argos.org>

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Mike Nowlin wrote:
> Agreed, but this may be quite a project...  doing a "cd ~bob" would be
> fun.  :)  You would pretty much have to implement some timing
> requirements, but I imagine that it could bulk up that section of the
> kernel pretty easily.

Yep. I started to hack something like this into sio.c in the days
of 2.1, then the need disappeared for a while and I never completed
it.

> One thing that might help (assuming you CAN
> generate a break) is to watch DCD (or some other control line(s)).

Yes. (DSR also jumps to mind.)

> Generally, when a break is sent intentionally, the DCD line is active --
> when the kernel detects a break, wait until after it's finished, then
> check DCD.  If it's high, drop to debugger.  If it's low, somebody either
> turned the terminal off or dropped outta kermit.

Excellent idea.

> (I have the displeasure of maintaining an AIX box that does something
> similar to this.  Before the upgrade that fixed this problem, turning off
> the serial console brought the whole machine down.)

Suns tend to do it too. Great fun when patch-monkeys disturb the
cable to the console... :-)
-- 
Phil Homewood             DNRC          email: philh@mincom.com
Postmaster and BOFH
Mincom Pty Ltd                          phone:  +61-7-3303-3524 
Brisbane, QLD Australia                 fax:    +61-7-3303-3269


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