# Suspending to RAM with hibernate-script

Related articles

- Suspend to RAM
- Suspending to Disk with hibernate-script
- pm-utils
- Laptop

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`.

However, `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 `s2ram`.

You can edit `/etc/hibernate/hibernate.conf` to select `ususpend-ram.conf` as the default action called by:

    # hibernate

Just put the following as the first uncommented line:

     TryMethod ususpend-ram.conf

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 `s2ram` method.

The hibernate-script options are exhaustively described in the man page `hibernate.conf`.

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 `/etc/hibernate/blacklisted-modules`.

If you discover that a module is guilty, you should report this to the suspend-devel@lists.sourceforge.net, 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 `--vbe_save` `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:

    SwitchToTextMode yes

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.

## Sound

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

    RestartServices alsa

# 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 `/var/log/acpid`.

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.

## Controlling wakeup

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

Category:

- Power management