6.x acpi powerbutton

Stephen Clark sclark46 at earthlink.net
Sat Apr 18 03:11:43 UTC 2009

Nate Lawson wrote:
> Ian Smith wrote:
>> On Fri, 10 Apr 2009, Nate Lawson wrote:
>>  > Andriy Gapon wrote:
>>  > > on 09/04/2009 23:24 Stephen Clark said the following:
>>  > >> Is there a reason it doesn't send and event like Linux that can be acted
>>  > >> upon by user space other
>>  > >> than signaling init? I like to have a message written in
>>  > >> /var/log/messages that someone pressed
>>  > >> the powerbutton.
>>  > > 
>>  > > I think that for all suspend states except S5 userland is notified via
>>  > > devd mechanism and potentially can veto the suspend. S5 (soft-off) is
>>  > > coded to start shutdown immediately. You can try to hack on
>>  > > acpi_ReqSleepState in sys/dev/acpica/acpi.c.
>>  > > 
>>  > > I am not sure what is the reason for this special behavior of S5. But I
>>  > > like it, because it sometimes allows me to perform semi-clean shutdown
>>  > > when X goes crazy. But I also see when it could be useful to have S5
>>  > > request go through userland. So this could be configurable.
>>  > 
>>  > The reason for userland getting into the loop in the first place was to
>>  > run programs to shut down devices and reinit them after resume. This
>>  > isn't necessary in the shutdown case because init already sends a
>>  > signal, as you mention.
>>  > 
>>  > There's already a mechanism for timing out if userland is not
>>  > responding, so a suspend will ultimately happen whether or not it
>>  > answers. However, that waits for a while (1 minute?) and devd used to be
>>  > optional, so I thought it best to keep the existing S5 behavior
>>  > (immediate shutdown).
>>  > 
>>  > It may be ok to enable this for S5 but I don't think it's very useful.
>> Perhaps a silly question, but is it too late at this stage of the game 
>> to try logging S5 events to syslog before dying?  I agree with Stephen, 
>> logging 'shutdown by powerbutton' surely beats what might otherwise 
>> resemble a spontaneous reboot?  Or is something already logged here?
> I'm not resisting this, but I'm having trouble seeing the importance.
> What happens differently than if someone hits CTRL-ALT-DEL on a virtual
> console?
Hi Nate,

We have over 500 units in the field that are used as firewall/vpn/routers. They 
have no console, but they do have a powerbutton. We have had customers say the 
machine turned itself off. It would be nice to know that someone pressed the 
power button.



"They that give up essential liberty to obtain temporary safety,
deserve neither liberty nor safety."  (Ben Franklin)

"The course of history shows that as a government grows, liberty
decreases."  (Thomas Jefferson)

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