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  From: Craig Markwardt <craigm@pcasun3.gsfc.nasa.gov>
  To  : Chris Worley <cworley@symbionsys.com>
  Date: Tue, 18 Jul 2000 20:47:13 -0400 (EDT)

Re: Using power switch to go into standby mode

Chris Worley writes:
 > Jont Allen wrote:
 > > Chris Worley wrote:
 > > >
 > > >
 > > > I looked at apmd_proxy, but I don't see how to specify: "if power off
 > > > then standby instead".
 > > 
 > > The response you got from Craig Markwardt is the definative answer.
 > > He said that "power off" is not supported by the apm kernel module.
 > 
 > It must be supported in the APM kernel module.  If I compile the kernel
 > without APM support, then the power switch has no effect (I have to pull
 > the plug).  Likewise, if I panic a kernel with APM support, the power
 > switch no longer works.

What I said was that the power switch was not programmable under the
APM specification.  Therefore there's nothing for the kernel module to
implement.

The BIOS may pass some power management messages to the kernel when
the button is pressed, like, "I'm about to power down!" or "Now
entering standby mode!" but those actions are determined by the BIOS,
not Linux.  The hardware is there, everything probably works, but
there's just no way for the APM BIOS to communicate these kinds of
events.  As David Brownell mentions, you may be able to configure it
from the BIOS menu.

The APM BIOS specification does allow the OS to turn off the machine,
and I believe that this is accomplished in combination with a newer
version of "shutdown".  I think some people connect control-alt-del or
sysrq to this shutdown function.  In principle I think you could
change this to "apm -s" or whatever.  Again, this doesn't solve the
problem of programming the power button.

The ACPI specification, however, provides lots of ways to program and
manage special hardware buttons and switches.  Here, it's built right
into the specification, so there needn't be any monkeying around in
the BIOS.  Of course, as I mentioned, the Linux ACPI support is still
rather embryonic.

It is likely that the QNX operating system (which originally ran on
your machine, yes?), was specially modified for the hardware.  Lots of
laptop manufacturers provide special software or Windows drivers that
access this manufacturer specific hardware.  If you can figure this
out, more power to you. :-)

Craig