Subject: power management and related concerns
To: None <>
From: Garrett D'Amore <>
List: tech-kern
Date: 06/30/2006 17:28:15
Well, I've made the mistake of looking at what we currently have in
NetBSD.  And comparing it with some real (our) hardware.

There are few quick points for discussion:

1) there doesn't seem a clear way to indicate powerfail for a low
battery condition in sysmon.  Should I just be sending init some signal?

2) No way to indicate overtemp status either

3) Currently it isn't clear whether you should be registering with APM,
sysmon, or something else for things like battery status, etc.  It would
be really, really good if drivers didn't have to do _both_ of these
things.  Can we maybe have a sysmon APM compatibility layer?  (I guess
there are some userland apps that "know" about APM.  Bletch.)

4) We need some userland tools to talk to sysmon in base, I think. 
(E.g. to query batteries, etc.)

5) In many respects, sysmon looks like a good start.  I've coded a quick
power management driver for the Ultrabook IIi (okay, it was mostly a
port from Solaris), and it basically works for things like lid switch,
AC power cord un/plug, and power button.

What do folks think?

Garrett D'Amore, Principal Software Engineer
Tadpole Computer / Computing Technologies Division,
General Dynamics C4 Systems
Phone: 951 325-2134  Fax: 951 325-2191