Understanding the power management

Guylhem Aznar olpc at guylhem.net
Sat Aug 18 21:34:17 EDT 2007


I am trying to figure out more about how power management work on the
OLPC. It's quite different from what I am used (acpi, etc) and the
documentation/scripts doesn't seem up to date

For example, I saw references to respeclaration in the xinitrc while
it's supposed to be unused and replaced

Here is my current understanding, based on the documentation I've read
and some tests. Please correct me if I'm wrong.

 - ohmd performs power management tasks when ordered to do so by the hal on dbus
but killing it does nothing bad (??) so which purpose does it serves?
 - respeclaration has been replaced by the following tools to ask for
pm tasks execution :
    - hald-addon-inpt
    - olpc-hardware-manager
 - how are buttons mapped to pm tasks ? hald-addon-input apparently
does rotation/suspend. I am wondering about the others functions.
 - what is the role of olpc-hardware-manager? Execure ohmd dcon
requests ? Or manage ohmd?
killing it stops screen brightness, does not stop screen rotation
 dbus-daemon --system : is where they are talking
 console-kit-daemon : serves which purpose ??

I'm downloading a FC7 iso ATM to be able to fetch the git tree, (not
git on macports :-/) because the documentation doesn't help a lot.
Reading the code might be much more useful.

Meanwhile, I am still missing 2 things on power management
 - how to turn off display completely on standby (I know how to do a
freeze, now I would like to turn it off)
 - how to turn off wifi (flight mode) so that I can work on the olpc
next week. My day job is in an hospital where wifi is *not* allowed.


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