6.x acpi powerbutton

Ian Smith smithi at nimnet.asn.au
Fri Apr 17 19:21:49 UTC 2009

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?

cheers, Ian

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