TuxOnIce

General

Software Suspend 2, also called "swsusp2" and "suspend2", is an implementation of suspend-to-disk functionality in the form of a Linux kernel patch and several userspace utilities. It is an alternative to both the BIOS-driven hibernation feature found on most ThinkPad models, and the swsusp "software suspend" functionality built into recent Linux kernels.

Compared to the alternatives, Software Suspend 2 has some unique features:

• The ability to compress the memory image as it is written to disk, thereby reducing suspend and resume times.
• Saving the memory image into the swap partition or a file on a normal filesystem, instead of a dedicated partition
• Cancelling a suspend in progress
• Control over amount of RAM written to disk -- can (optionally) discard cached disk blocks to reduce suspend and resume times
• Textual and graphical UI (optional)
• Improved reliability under some circumstances -- if the alternatives don't work, try this one!

Since it is implemented purely in software, Software Suspend 2 is in principle machine-independent and should work on all modern ThinkPad models. However, in some cases problematic driver need to be unloaded before suspension.

Model-specific Status

• ThinkPad T43: works; requires SATA resume patch and the SATA drivers compiled as built-in or in initrd (see Problems with SATA and Linux)
• ThinkPad T21: works; need to unload the sound module (snd-cs46xx) on suspend. May want to enable UseDummyXServer if running X.
• ThinkPad X41 Tablet: works; requires SATA resume patch and the SATA drivers compiled as built-in or in initrd (see Problems with SATA and Linux) and a hibernate.conf fix (see Installing Fedora Core 4 on a ThinkPad X41 Tablet)
• ThinkPad X22: works (see Installing Ubuntu (Breezy) on a ThinkPad X22)
• ThinkPad G41: works (see Installing Debian on a ThinkPad G41)

Installation Instructions

The project home page has a detailed HOWTO and FAQ. The following are just a few highlights.

Patching mkinitrd

If your systems uses an initrd file (most do), you'll need to patch or replace your initrd-creation script.

• Fedora: in /sbin/mkinitrd, find this line:

echo "echo Mounted /proc filesystem" >> $RCFILE

and add the following immediately afterwards:

echo "echo > /proc/suspend2/do_resume" >>$RCFILE

• Debian: copy swsusp-initrd.sh script to your /etc/mkinitrd/scripts directory before creating initrd image.

Make sure you (re)install your kernel after patching mkinitrd.

Hibernation script

Software Suspend 2 works best with a hibernate script, which takes care of auxiliary tasks needed on many systems (e.g., unloading problematic modules and restoring video modes).

Availability:

• Gentoo: emerge hibernate-script
  
• Fedora: kernel and hibernate RPMs are available at http://mhensler.de/swsusp/
  
• Other: check the home page for packages (deb, i386 rpm, tgz, and source rpm) from http://www.suspend2.net

External links

• Project home page