Hibernate (OS feature)

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Hibernate is a feature seen in many operating systems where the contents of RAM is written to non-volatile storage, such as the hard disk (as either a file or on a separate partition) before powering off the system. Hibernating and restoring from hibernate is generally faster than a cold boot and, if necessary, can be done without user interaction (unlike shutting down, which often requires the user to specify if open documents should be saved). To use hibernation the hard disk needs to have at least as much free space as there is RAM on the system.

Hibernation is often used on laptops and can generally be set to happen automatically on a low battery alarm. Early implementations of hibernation did use the BIOS but on modern systems the functionality is usually handled by the operating system. Hibernation is defined as sleeping mode S4 in the ACPI specification.

Contents

1 Operating System support

1.1 Windows
1.2 Mac OS
1.3 Linux

2 See also
3 External links

Operating System support

Windows

Microsoft Windows 2000 and later support hibernation at the operating system level without special drivers from the hardware manufacturer.

Mac OS

Safe Sleep, the Mac equivalent of hibernate, has been available for new Mac models starting with an October 2005 revision of the PowerBook. Subsequently, a crack was made available to enable this feature for much older Mac computers running OS X 10.4. Classical Mac OS once also supported hibernate, but this feature was dropped by Apple.

Linux

In the Linux kernel, Hibernate or suspend-to-disk is implemented by swsusp which is inbuilt into the 2.6 series. An alternative implementation is Suspend2 which is available as patches for the 2.4 and 2.6 kernels. It provides advantages such as support for SMP, 4GB high mem and preemption. Currently work is being done on merging Suspend2 into the mainline kernel.

External links