ACC SHELL

"Smart" selections of parameters for suspend to RAM
===================================================

This release of pm-utils implements a "smart" selection of the best
parameters for suspend to RAM. See http://en.opensuse.org/S2ram for
more information on the possible parameters.

How does it work?
=================
There are several sources of so called "quirk lists", which describe
what special hacks are necessary on a given machine:
- the s2ram whitelist, compiled into the s2ram binary
- HAL's quirk list
- drivers for specific chipsets that know how to bring the video card
  back to life.

When preparing suspend, pm-suspend goes through the following workflow:

1) It checks if the S2RAM_OPTS variable is set in a configuration file
   in /etc/pm/config.d/. If it is, the options in that variable are
   used for suspend.
2) It checks if one of the card specific modules is loaded (right now
   those are i915 (for Intel graphics), nvidia and fglrx (for ATI).
   If it finds one of those, it assumes that they can handle suspend
   and uses no other options.
3) It checks if the machine is in the s2ram whitelist. If the machine
   is known there, the s2ram whitelist is used.
4) It get the options that HAL passed on the pm-suspend command line
   and uses those.
5) If nothing is found yet, suspend will fail.

How can I influence it, in case something goes wrong?
=====================================================
In case one of the card specific modules is loaded, but unable to restore
after suspend, and the machine is known to either HAL or s2ram, you can
select the source of quirks with the variable S2RAM_QUIRKS_SOURCE. Set
it like this:

	S2RAM_QUIRKS_SOURCE="hal"	# for HAL
or
	S2RAM_QUIRKS_SOURCE="s2ram"	# for the s2ram whitelist

Note that the s2ram whitelist is only used if the machine is actually
known by s2ram.

In case the machine is unknown, try to find out the correct options (see
http://en.opensuse.org/S2ram for details) and put them into S2RAM_OPTS.

Where do I put those variables?
===============================
Just create a file in /etc/pm/config.d/, e.g. named "suspend":

/etc/pm/config.d/suspend

and put the variable in there. This config file is sourced by a shell,
so it needs to have valid shell syntax.

Under the hood
==============
Note that the "low level" suspend stuff is still done by the s2ram and
s2disk tools and that pm-utils is usually called by the desktop applets
(like "gnome-power-manager", "powerdevil" (KDE4) or "kpowersave" (KDE3)
via HAL. Keep this in mind when debugging suspend problems ;)

Further reading
===============
Up to date documentation is available at

	http://en.opensuse.org/S2ram
	http://en.opensuse.org/Pm-utils


Have a lot of fun...