Re: Generic battery interface

Marek Wawrzyczny
2006-08-02T07:46:36Z

On Wednesday 02 August 2006 17:18, Jean Delvare wrote:
> Hi Pavel,
>
> > > frequently it can read from the chip. And no hardware monitoring chip I
> > > know of can tell when the monitored value has changed - you have to
> > > read the chip registers to know.
> >
> > ACPI battery can tell when values change in significant way. (Like
> > battery becoming critical).
>
> Ah, good to know. But is there a practical use for this? I'd suspect
> that the user wants to know the battery charge% all the time anyway,
> critical or not.

Yes, the user may want to know the battery state all the time, but will not
notice the difference between the system reporting battery changes every 100
microseconds or every 10 seconds, unless the hardware eats its battery
sources for breakfast?

The system cares though, very much so in fact:

If the battery becomes critical the system should either shut down or suspend
to disk (if this is supported).
This obviously would be triggered by some sort of daemon (powersaved comes to
mind).
Ideally the suspend to disk or shutdown event triggers another event that
allows any desktop to save it's state or possibly unmount shares that could
otherwise be corrupted.

This scenario is quite different to an application reading the battery level.

Marek Wawrzyczny