swsusp (Software Suspend) is a suspend-to-disk implementation in the 2.6 series Linux kernel. It is the Linux equivalent of Windows hibernate functionality. To enable swsusp, the following should be selected during kernel configuration :

Power management options ? <*>Power management support (CONFIG_PM) 
Power management options ? <*>Software Suspend (CONFIG_SOFTWARE_SUSPEND) 
Power management options ? [/dev/resume_partition]Default resume partition (CONFIG_PM_STD_PARTITION) 

The /dev/resume_partition needs to be replaced by the actual swap partition that is to be used for suspending. Otherwise resume=/dev/resume_partition can be given as a parameter during system bootup. The actual suspend is done by :

echo shutdown > /sys/power/disk; echo disk > /sys/power/state

swsusp lacks some features, such as compression and graphical progress indication. You can still get them, 2.6.18+ kernels allow suspend to be controlled from userspace.

See also

• TuxOnIce
• muswsusp userspace software for suspending to ram and/or disk