Ubuntu Wiki

• Launchpad entry: https://launchpad.net/distros/ubuntu/+spec/power-management-configuration

• Created: Date(2005-04-23T01:36:42Z) by MattZimmermanBR

• Contributors: MatthewGarrett, OliverGrawert, MatthewPaulThomas, ThomMay, ReinhardTartler, RyanLortie, CoreyBurger, MatthiasUrlichs, MartijnVanDeStreek, DanielHolbach

• Drafter: DanielHolbach

• Assignee: RyanLortie

• Packages: gnome-power, gnome-session, gnome-applets

Summary

GNOME Power Preferences should by default only propose controversial options (ie: if we suspend when the lid closes). Other options have sane defaults which we should select for the user and not ask them about. For example, the following events are assumed to behave as follows:

• power button press -> logout dialog

• suspend press (if exists) -> suspend

• ac unplugged -> so what? (do nothing -- but go into laptop mode!)

Rationale

There should be simple, reliable, and understandable methods of:

• shutting down the computer
• putting the computer into a low-power-use state
• going into a low-power-use state after some period of inactivity
• blanking the screen, instead of using a power-sapping screensaver, when running on battery power
• preventing data loss when the battery runs out.

Currently people need to edit text files in /etc to enable suspend to RAM, and to select which services will be restarted. Also, it's currently impossible to configure how the system should behave in various situations, such as on lid close. All of these points should be configurable graphically.

Use Cases

• Michael is a harried Hong Kong businessman who has just installed Ubuntu 6.04 on his home desktop machine. He doesn't care about power management; he wants it to just work and do the right thing.

• Mei-li is flying back to her home in London after a successful business trip to Hong Kong (during which she persuaded Michael to install Ubuntu). She does as much work as she can on her ThinkPad during the flight, with Ubuntu automatically putting the machine into hibernation when the battery reaches a critically low level. Nineteen hours later, Mei-li arrives back at her apartment, plugs in her ThinkPad, opens it up and resumes work from where she left off.

• Candice runs a university computer lab containing 60 iMacs -- a significant use of electricity for a university on a tight budget (they upgraded from Mac OS 9 to Ubuntu partly because it was cheaper than OS X). Candice wants each computer to go to sleep if idle for half an hour, and she does not want students to be able to alter the power management settings.
• Bob runs the IT department at Hydroponical Light Industries. He gives his salespeople laptops with Ubuntu preinstalled, but since they're salespeople and not tech wizards, Bob locks down the power settings so they can't be messed with.
• Courtney shares her Presario with her evil twin sister, Tara. Tara likes playing practical jokes, and tries to set up a cron job to spontaneously shut down or suspend the system if Courtney is logged in. This is unsuccessful.

Design

Panel Icon

There will be exactly one power status icon on the panel (either applet or notification icon), which will show the current battery charge status. The icon will only show "primary" battery status (we make no attempt to deal with wireless mouse batteries, for example). The icon will not have its own preference dialog, but rather, a pulldown menu. The preferences item in this menu will lead to the global power preferences dialog (same dialog that is accessed via the System -> Preferences menu).

+-----------------------------+
|    _Power Preferences...    | -> system power preferences
|(o) No text                  |
|( ) Remaining time           |
|( ) Percentage Charge        |
+-----------------------------+

(NB: RyanLortie is currently working on this patch for battstat-applet)

Power Off Dialog

+-----------------------------------------------+
|                                               |
| [     ]                                       |
| [  ?  ] Are you sure you want to power off?   |
| [     ]                                       |
+-----------------------------------------------+
| (_Restart) (_Sleep)  (_Cancel) ((_Power Off)) |
+-----------------------------------------------+

• Power button -> pop up the power off dialog

• dialog box must be there -very- fast. don't do fading screen effect if we can't do it quickly (NB: gnome logout dialog does it slow but gnome-screensaver can do it quickly. find out why.)
• all options in dialog are accessible with single (no need to hold alt) keypress.
• default is poweroff, accessible by pressing enter
• button order is important here. this is according to the gnome HIG. the only negotiable items are the restart and sleep buttons.

Power Preferences Dialog

If Suspend is supported:

+-----------------Power Preferences-------------------------+
|   When Running on batteries:                                |
|    Dim the displayer after:        +---------||---+         |
|                                              50min          |
|    Turn the display off after:     +---------||---+         |
|                                              50min          |
|    Put computer to sleep after:    +---------||---+         |
|                                              50min          |
|                                                             |
| Options                                                     |
|   [x] Suspend on lid close:                                 |
|   [x] require password when                                 | 
|       waking from sleep/hibernate                           |
|   [x] notify when battery is done charging                  |
|                                                             |
| Battery Low Warning                                         |
|    Issue warning when time left falls to:  +---------||---+ |
|                                         15 min remaining    |
|                                                             |
+-------------------------------------------------------------+ 

• one tab
• if suspend is unsupported then:
  • - hide suspend time slider - hide suspend-on-lid-close option
• time until automatic suspend
• checkbox for suspend on lid close
  • - defaults to on if suspend is whitelisted for laptop
• checkbox for "require password when waking from sleep/hibernate"
  • - defaults to off if user is autologin - essentially, invoke the screensaver just before suspending
• sliders for battery low in TIME (not percentage)
  • - warnings issued for battery low - automatic shutdown for battery critical
    • - automatic shutdown may be disabled by hidden gconf key
• we intentionally don't consider, for example, putting the computer to sleep when on AC.
• the lock-on-sleep option has no effect on the normal behaviour of the screensaver.

Implementation Plan

In its current state, gnome-power-manager is insufficient for our purposes. The primary problem is that it runs as a gnome session daemon. This causes three problems:

• Kubuntu and Xubuntu get no love
• power management doesn't work when at the login screen
• security issues are introduced if any user (logged in or not) can ask the system to immediately suspend (as is the current case with g-p-m).

The plan is to attempt to work with upstream to address these changes. Specifically, we have asked the following:

• We require a system policy daemon running as root.
• Users in group power-config will be able to change power config without password.
• Users not in this group are prevented from modifying the settings.
• Use dbus to talk to system daemon, which will make certain they are in the right group.
• We prefer to have each user able to specify their own settings.
• If each user can set their own settings then there must be a clear way to set defaults (for new users, login screen) possibly only accessible to admin user.
• If each user can set their own settings then the new settings must be activated when the user logs in and the default settings must be restored on user logout.

If upstream is willing to work with us then gnome-power-manager will be shipped. If we can't get gnome-power-manager into an acceptable state on time then we will fall back on the default action of continuing with our current power management scripts with a configuration interface added on.

Outstanding issues

• How do we cater for Bob's use case?
• How do we cater for Courtney's use case?