Subject: Re: reboot due to critical battery level
To: Jared D. McNeill <>
From: Steven M. Bellovin <>
List: tech-kern
Date: 12/20/2007 14:17:28
On Thu, 20 Dec 2007 14:10:08 -0500
"Jared D. McNeill" <> wrote:

> On 20-Dec-07, at 1:34 PM, Steven M. Bellovin wrote:
> > You need *some* power for suspend.  It's also why I do a sync in
> > the suspend process, though I believe the current ACPI code does
> > that automatically.  The problem that shutdown loses application
> > data.  If I'm editing a file, I want time to save it.  In other
> > words, while clean shutdowns of file systems are important, clean
> > shutdowns of applications are important, too.  (The shutdown command
> > in powerd/scripts/sensor_battery *really* needs to do a 'shutdown
> > +5' instead of a 'shutdown now'.  However, it probably needs an &
> > after it, since it appears from other interactions -- I haven't
> > checked this thoroughly -- that powerd blocks waiting for scripts
> > to finish.  There also needs to be an easy way to cancel the
> > shutdown.  Often, for example, I'm working in a comfortable chair
> > and don't want to bother dragging out the power adapter.  When I
> > get the "your battery is really, really low" warning, I either
> > suspend and move to my office or I do go to the trouble of finding
> > the power cord...    Either way, I need to cancel the shutdown.)
> Again, I suggest you actually look at powerd and pmf. You get ample
> warning before we force a shutdown, plenty of time to notify yourself
> before it reaches critical state.

I have looked at powerd and parts of pmf.
> If you're cooking in the kitchen, and you feel heat, do you move your
> hand away when it feels warm or when it is on fire?
There are times when I tolerate -- or risk -- more heat.  It depends on
the situation.

		--Steve Bellovin,