ACPI Events

Duane Morin dmorin at lear.morinfamily.com
Tue Nov 11 13:16:34 EST 2003


How do ACPI events work?  If I write a simple 
loop that cats out /proc/acpi/button/lid/LID/state over and over, then
open and close the lid of my laptop, it says open/closed as I would
expect.  Interestingly, if I just loop tightly it does not -- but if I 
throw a sleep in there, it does.

I see events in /var/log/acpid, but can't make them happen.  For instance
there is a LID event at 11:01:17 today.  It is now 12:54.  Hang on 
while I close the lid for a few seconds...

...it's 2 minutes later.  No entry in the log.

Will it show up later?  Did I not leave the lid closed long enough?  I 
have no idea.  Whatever I was running at 11:01 I'm running now, so I dont 
think it's a failure to run acpid properly or something.  And I can se 
ethat the state changes immediately so I dont know why the event wouldn't 
happen with at least a few seconds turnaround time.

What is the relationship to acpid and events?  Does it monitor /proc/acpi 
and then generate the events?  Or does it merely listen to events being 
generated and then attach actions to them?

Duane





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