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From: chap@art-sy.detroit.mi.us (j chapman flack)
Newsgroups: comp.unix.sysv386,comp.unix.wizards,comp.unix.internals
Subject: Re: SIGPWR signal in system v
Message-ID: <9105130940.aa03108@art-sy.detroit.mi.us>
Date: 13 May 91 13:40:28 GMT
References: <1991May6.112253.5344@cs.tcd.ie>
Sender: chap@art-sy.detroit.mi.us (j chapman flack)
Reply-To: chap@art-sy.detroit.mi.us (j chapman flack)
Organization: Appropriate Roles for Technology
Lines: 36

In article <1991May6.112253.5344@cs.tcd.ie> ohurley@cs.tcd.ie (Oisin Hurley) writes:
>
>Does anybody out there have information on the SYS V SIGPWR signal? The man
>says that this signal occurs if there's a power failure. I have a couple of
>questioned which I haven't been able to answer myself:

I, too, would like information on this facility.

>2. How far ... 3. How long ... 4. ... generated on mboard or line from the psu?

I assume the answers to those questions are very system-dependent.  Somewhere
there has to be hardware that detects a power drop and asserts an IRQ, and I
suppose somewhere there has to be a driver that handles that IRQ and causes
signals to be sent.

I have SCO SysV/386, and have been looking seriously at the ITT PowerMate,
which is several minutes' worth of battery on a card (internal) which will
assert an IRQ when it senses main power dropping and goes to batteries.
I assume I'll need to write a driver with an interrupt handler for that,
and that the driver should call some kernel routine that causes SIGPWRs to
be sent.  Can anyone offer details?

... My man page for `init' says that if init receives a SIGPWR, it will
fire up anything in /etc/inittab with type 'powerfail' or 'powerwait'.
I experimented with "kill -19 1" to send init a SIGPWR (19) after putting
some 'powerfail' entries in inittab; it didn't do diddley.  Either init
doesn't really support SIGPWR as documented, or "kill -19" doesn't send a
SIGPWR, or I'm missing something else.  Ideas?

I don't have the development system (yet) which is why my experiments are on
such a superficial level so far.
-- 
Chap Flack                         Their tanks will rust.  Our songs will last.
chap@art-sy.detroit.mi.us                                    -MIKHS 0EODWPAKHS

Nothing I say represents Appropriate Roles for Technology unless I say it does.