Re: core dumps on signals

Alan Cox (alan@lxorguk.ukuu.org.uk)
Fri, 26 Feb 1999 15:30:19 +0000 (GMT)


> > PWR n/a exit (normal systems would ignore by default)
>
> I don't think so; SIGPWR sent to init means it should shut down the
> system as soon as possible. If init dies, the system gets uncleanly

Not exactly. SIGPWR is a "Power Restored" in SYS5 unix such as the NCR
tower. This is quite a common confusion.

The way NCR use it for example on the old towers is that the box has
a battery (a big one), when the power goes off it switches to battery
and hibernates. This works well - we've carried machines between floors
without rebooting.

Now when the power comes back on the machine knows the other devices will
have failed, so the SIGPWR causes the I/O coprocessor daemons (hpsiod) to
download firmware again, and it also causes things like vi to refresh the
screen (since the terminals will potentially have lost power).

Its _very_ neat when the power comes back on, and the machine refreshes your
display for you

Alan

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