Re: Should battery generate events?

[David Bronaugh <dbronaugh-Jp3n8lUXroSX6QiC4yPwbg@public.gmane.org>]

Tim Dijkstra wrote:

>Hi,
>
>Last week my laptop (Acer Travelmate 636Lci) run out of power resulting
>in a unclean shutdown, disk corruption and me spending a few evenings to
>get it to sanely work again.
>
>I would want to avoid this happening again. Ideally I would want my
>laptop to "shutdown -h now" if battery power is to low (well rather have
>it go to S3 or softwaresuspend, but it seems hopeless to get that to
>work :(  
>
>>From some googl'ing I get the impression that ACPI should generate
>battery events on a change of capacity or at least when it's low. My
>idea was to have acpid call some script on battery events. 
>The problem is that there doesn't seem to be such events on my machine. 
>  
>
Whenever polling is required, this is expected to be done in userspace, 
not in kernelspace. There's a long history of people asking "why doesn't 
battery status changes generate events" and a long history of people 
saying "because it would require polling in either acpid or the kernel, 
which is a Bad Thing(tm)".

If you'd like something to watch the battery capacity, perhaps you 
should use something like KLaptop -- you can configure it to run a 
command (like 'echo -n "disk" > /sys/power/state') on low and/or on 
critical battery level warnings. Since it tracks this kind of state, you 
don't have to.

Of course, KLaptop's not the only option -- it's just what I have here.

David Bronaugh


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