SuspendHowto

Revision 11 as of 2006-06-06 19:42:55

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NOTE: Suspend support is included in the Hoary release. Hoary users should see ["HoaryPM"]

Introduction

Suspend mode is a special low-power mode, often used on laptops, that preserves the contents of RAM while conserving power.

There are two different standards for power management (which handles suspend in Linux), ACPI and APM. ACPI has more advanced features, but is only found on computers made in the last few years. APM is older, and somewhat more mature, but doesn't offer as many features as ACPI. It also isn't available on many new PCs.

Also, there are two main forms of suspend - suspend-to-RAM and suspend-to-disk (also known as "software suspend" or "hibernation"). Suspend-to-RAM uses more power, but is almost instant. Suspend-to-disk, on the other hand, uses no power (the system actually powers off), but takes longer to suspend/resume. This HOWTO will discuss all of these methods.

WARNING: This is not officially supported in Ubuntu Warty, and may cause system problems or data loss. Use with caution.

Suspending to RAM (APM)

To enable APM on a system, edit your /etc/modules file and add apm to the list of modules. Also, edit the #kopt line of your /boot/grub/menu.lst file so that it ends with apm=on, and then run sudo update-grub to update the GRUB configuration. Add the modules shpchp and pciehp to the end of the /etc/hotplug/blacklist file (they don't work w/APM). Finally, reboot the computer. If your system supports APM, everything should be set up. Close the laptop lid (if you have a laptop) or press the Sleep button to suspend to RAM.

Some systems may not work properly with this, and many new systems don't support APM at all. In this case, search for information on suspending your particular laptop in the wiki or elsewhere. Also, if APM doesn't work, try ACPI. Note that APM doesn't support all the power management features of many newer laptops, and also doesn't work with suspend-to-disk using the code in the kernel.

ACPI

To suspend to disk, choose "Hibernate" from the GNOME logout menu. To suspend to RAM, edit

/etc/default/acpi-support

and uncomment the second line by deleting the # character, to read:

{{{ACPI_SLEEP=true }}}

Ubuntu 6.06

Dapper needs another step to enable suspend. Execute gconf-editor, and visit apps/gnome-powermanager and enable "can_suspend". You can enable/disable suspend and/or hibernation from there.

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