Suspending to RAM with hibernate-script
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In this article we will explain how to accomplish a successful suspension to RAM using hibernate-script.
Different methods of suspending to RAM
There is an application, called
s2ram, which contains a "whitelist" of known laptop models and, according to what has been reported by other owners of these laptops, tries to do the right things for that specific laptop. The whitelisted laptops can therefore use
s2ram to suspend to RAM "out of the box". Non-whitelisted laptops need to try different command line options of
s2ram in order to determine - by trial and error - the appropriate "tricks" needed to make suspend and resume work. Your experience, if reported to the
s2ram developers, will contribute to whitelist your machine in the next release of
s2ram is not the only resource: the hibernate-script, which is commonly used to accomplish Suspend to Disk , supports also suspension to RAM and proposes some further tricks which could convince your machine to suspend to RAM and resume properly. Moreover, the hibernate-script can automatize other useful operations which you could want/need to do before suspension or after resuming from suspension to RAM.
Thus, the first part of this article will be devoted to
s2ram. The second will discuss the use of the hibernate-script in suspension to RAM. In particular, we will see how the hibernate-script can be used to suspend to RAM your system just with the
s2ram, but providing some additional tweakings. Finally, we will mention the possibility to suspend the machine both to RAM and to disk.
The hibernate-script and suspension to RAM
The hibernate-script, developed in the field of the tuxonice project for suspend-to-disk method, can be used also to suspend your machine to RAM. Actually, you can also try to do this directly, performing the required operations before calling the ACPI S3 state. However, the
s2ram seems to be the leading method nowadays and, through the named whitelist, should assure in the future that virtually any laptop can suspend to RAM without too much hassle. So, the actually best way to use the power of the hibernate-script for suspension to RAM is to use it to call
You can edit
/etc/hibernate/hibernate.conf to select
ususpend-ram.conf as the default action called by:
Just put the following as the first uncommented line:
However, may be that you want to use the hibernate-script primarily to suspend to disk. In that case you should resort to the ram-specific configuration file from the command line:
# hibernate -F /etc/hibernate/ususpend-ram.conf
Now you should configure the script. Please note that the options that you put in
/etc/hibernate/common.conf will be used anytime you call hibernate (that is also for suspension to disk). On the contrary, the options in
/etc/hibernate/ususpend-ram.conf will be used only when you suspend to RAM with the
The hibernate-script options are exhaustively described in the man page
First of all, may be that some module is preventing you from accomplishing a proper suspension cycle. In this case, list it in the UnloadModules: it will be unloaded before suspension and reloaded after resuming. Note that the hibernation script already does this for some blacklisted modules, whose list is
If you discover that a module is guilty, you should report this to the firstname.lastname@example.org, so that the bad behaviour of the module can be fixed.
May be also that your display is the guilty and that the tricks provided by
s2ram are not enough. The hibernate-script has some further tricks:
The relevant block of options is the following:
### vbetool #EnableVbetool yes #RestoreVbeStateFrom /var/lib/vbetool/vbestate #VbetoolPost yes # RestoreVCSAData yes
### xhacks #SwitchToTextMode yes #UseDummyXServer yes #DummyXServerConfig xorg-dummy.conf
However, most of these tricks are already attempted by
s2ram and you should not duplicate the effort. Only three tricks in this section are specific to the script. The first is to uncomment both the following two lines:
EnableVbetool yes RestoreVbeStateFrom /var/lib/vbetool/vbestate
Please note that, while
s2ram uses an internal vbetool component, the hibernate-script relies on the vbetool package in the extra repo, so you should install it. Basically, this combination of options do something similar to the
s2ram option, but, instead of restoring the state saved immediately before suspension, it restores a state manually saved by the user in the file /var/lib/vbetool/vbestate (or any other file you have chosen). You can try to save the state in a peculiar safe situation, like immediately after booting, or before any switching from X to console and back. You can save the state with the following command:
# vbetool vbestate save > /var/lib/vbetool/vbestate
The second peculiar trick (very often required!) is to uncomment the following line:
The script will switch from X to console before suspension and back to X after a successful resuming.
Finally, the UseDummyXServer trick uses a second XServer, with a minimal safe configuration only during the suspension cycle, restoring the full fledged X server only after a complete resume. This can be useful with cards with problematic proprietary drivers: the dummy xserver will use the standard vesa driver instead. Anyway, this last trick should be seldom useful nowadays, because also proprietary drivers seem to support suspension without too many problems.
The hibernate-script gives you many other useful possibilities (such as restarting services, unmounting partitions, ejecting pccards, and so on). Read about them in the man pages.
If you do not explicitly restore the volume level, ALSA may have the sound channels muted after resuming. If this happens, you can edit
/etc/suspend.conf by adding
Automatic suspend and wakeup
Once you have suspend to RAM working, you will probably want it to happend automatically e.g., when you close the laptop lid.
There are several ways to do this. The easiest is to use a high-level power management tool such as KDE's PowerDevil. Another is to create your own ACPI event handler scripts.
Automatic suspend, the hard way
ACPI events are managed by configuration files in
/etc/acpi/events/. (The laptop-mode-tools package contains some examples). A default configuration file called 'anything' is provided by the acpid package, which runs
/etc/acpi/handler.sh on every event.
An simple event configuration file to manage the opening and closing of a laptop lid (that could be called
/etc/acpi/events/lid) looks like this:
event=button[ /]lid action=/etc/acpi/actions/lid_handler.sh %e
The first line specifies the names of the events applicable to this file with a regexp. You can get the names of events by enabling event logging in acpid and looking at
The second line specifies an executable to be run when an applicable event occurs. The
%e is a variable containing arguments that the event provides. It's a good idea to provide them to the program.
It's customary to put handling programs in
/etc/acpi/actions/. A possible implementation of
lid_handler.sh in the previous example could be:
#!/bin/sh # check if the lid is open or closed, using the /proc file if grep closed /proc/acpi/button/lid/LID/state >/dev/null ; then # if the lid is now closed, save the network state and suspend to RAM netcfg all-suspend pm-suspend else # if the lid is now open, restore the network state. # (if we are running, a wakeup has already occured!) netcfg all-resume fi
The same example, adapted for wicd instead of netcfg:
#!/bin/sh # check if the lid is open or closed, using the /proc file if grep closed /proc/acpi/button/lid/LID/state >/dev/null ; then # if the lid is now closed, save the network state and suspend to RAM /usr/lib/wicd/suspend.py pm-suspend else # if the lid is now open, restore the network state. # (if we are running, a wakeup has already occured!) /usr/lib/wicd/autoconnect.py fi
Remember to make it executable. With some basic knowledge of shell scripting, you have a lot of possibilities.
The ACPI events that trigger wakeup are controlled through the procfile /proc/acpi/wakeup. An example output is:
root@hex in /proc/acpi $ cat wakeup Device S-state Status Sysfs node LID S3 *enabled PBTN S4 *enabled MBTN S5 enabled PCI0 S3 disabled no-bus:pci0000:00 USB0 S0 disabled pci:0000:00:1d.0 USB1 S0 disabled pci:0000:00:1d.1 USB2 S0 disabled pci:0000:00:1d.2 USB3 S0 disabled pci:0000:00:1d.3 EHCI S0 disabled pci:0000:00:1d.7 AZAL S3 disabled pci:0000:00:1b.0 PCIE S4 disabled pci:0000:00:1e.0 RP01 S4 disabled pci:0000:00:1c.0 RP02 S3 disabled RP03 S3 disabled RP04 S3 disabled pci:0000:00:1c.3 RP05 S3 disabled RP06 S3 disabled
To toggle whether an event will trigger a wakeup, pipe its name into the /proc/acpi/wakeup. (Note that every name in the file must have 4 letters, so if it is shorter e.g. LID, it needs be prepended with spaces). So to prevent opening the laptop lid from triggering a wakeup, you could do:
root@hex in /proc/acpi $ echo " LID" > wakeup root@hex in /proc/acpi $ cat wakeup Device S-state Status Sysfs node LID S3 *disabled PBTN S4 *disabled MBTN S5 disabled PCI0 S3 disabled no-bus:pci0000:00 ...
Another thing to note is that the PBTN and MBTN events were also toggle with the LID event. Sometimes events are linked, so that all of them will be enable and disabled in unison. Checking the 'dmesg' command can confirm this:
root@hex in /proc/acpi $ dmesg ... ACPI: 'PBTN' and 'LID' have the same GPE, can't disable/enable one separately ACPI: 'MBTN' and 'LID' have the same GPE, can't disable/enable one separately
This may not actually affect the other events. On a Dell Inspiron 6400, for example, the power button always triggers a wake up. Your mileage may vary.
None of this will persist between boots, so you might want to add the echo command to
/etc/rc.local so it is executed on every boot:
# disable the laptop lid switch echo " LID" > /proc/acpi/wakeup