end-user support: Battery alarm

end-user support: Battery alarm

[Mirko Hessel-von Molo]

Dear all, 

I have a probably stupid question for which I couldn't find the 
answer anywhere else. 

Is it true that a 'battery' event is raised by the kernel when the 
'current capacity' given in /proc/acpi/battery/BAT0/state goes below 
the limit defined in /proc/acpi/battery/BAT0/alarm?

I'm trying to use the battery alarm to make my system warn the user
and shutdown, if necessary. 

My setup is the following: I'm using a Dell Latitude D800 with BIOS A07,
running under Linux with Kernel 2.6.7 (not the latest one, I know).
As I 'organically evolved' the system from a RedHat 7.3 base install,
I'm reluctant to upgrade to some distro which provides acpi support. 

So far, I got pretty much everything to work, ac_adapter and battery events
are raised when the power supply changes. However, no event is 
raised when the battery capacity goes below the warn level. I can't remember
where I have read this, but somehow I got the idea that this should be the
case.

Does anyone have an idea where my problem could be?

Thanks for any help, 

Mirko

-- 
-------------------------------------------------------------------------------
Dipl.-Math. Mirko Hessel-von Molo                       Room : D3.310
University of Paderborn, Institute for Mathematics      Tel  : +49 5251 60 3774
Applied Mathematics                                     Fax  : +49 5251 60 4216
33095 Paderborn                                         Email: mirkoh-yTMzxJmGYpQ@public.gmane.org



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Re: end-user support: Battery alarm

[Rich Townsend]

Mirko Hessel-von Molo wrote:
> Dear all, 
> 
> I have a probably stupid question for which I couldn't find the 
> answer anywhere else. 
> 
> Is it true that a 'battery' event is raised by the kernel when the 
> 'current capacity' given in /proc/acpi/battery/BAT0/state goes below 
> the limit defined in /proc/acpi/battery/BAT0/alarm?
> 
> I'm trying to use the battery alarm to make my system warn the user
> and shutdown, if necessary. 
> 
> My setup is the following: I'm using a Dell Latitude D800 with BIOS A07,
> running under Linux with Kernel 2.6.7 (not the latest one, I know).
> As I 'organically evolved' the system from a RedHat 7.3 base install,
> I'm reluctant to upgrade to some distro which provides acpi support. 
> 
> So far, I got pretty much everything to work, ac_adapter and battery events
> are raised when the power supply changes. However, no event is 
> raised when the battery capacity goes below the warn level. I can't remember
> where I have read this, but somehow I got the idea that this should be the
> case.
> 
> Does anyone have an idea where my problem could be?
> 

Yes; I've no doubt that this is due to a broken DSDT. Unless Dell has 
put something in the DSDT that causes periodic polling of the battery 
level, there is no way a notification will be sent when the battery 
passes the trip point. There is certainly nothing in the Linux kernel 
that handles the polling.

cheers,

Rich


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