Difference between revisions of "Suspend to RAM"

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m (kernel (swsusp): provide link to better resource)
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[[Category:Power management]]
#REDIRECT [[Suspend and Hibernate]]
{{Article summary start}}
{{Article summary text|Provides general overview of methods for suspending Arch Linux system.}}
{{Article summary heading|Related}}
{{Article summary wiki|Pm-utils}}
{{Article summary wiki|Uswsusp}}
{{Article summary wiki|TuxOnIce}}
{{Article summary wiki|Suspending to RAM with hibernate-script}}
{{Article summary end}}
From [[Wikipedia:Sleep mode]]:
:''Sleep mode can go by many different names, including '''Stand By''', '''Sleep''', and '''Suspend'''. When placed in this sleep mode, aside from the RAM which is required to restore the machine's state, the computer attempts to cut power to all unneeded parts of the machine. Because of the large power savings, most laptops automatically enter this mode when the computer is running on batteries and the lid is closed.''
This article describes generally mechanisms to suspend Arch Linux system to memory. There are multiple low level interfaces (backends) providing basic functionality, and some high level interfaces providing  tweaks to handle problematic hardware drivers/kernel modules (e.g. video card re-initialization).
== Low level interfaces ==
Though these interfaces can be used directly, it is advisable to use some of [[#High level interfaces|high level interfaces]] to suspend/resume. Using low level interfaces directly is significantly faster using any high level interface, since running all the pre- and post-suspend hooks takes time, but hooks can properly set hardware clock, restore wireless etc.
=== kernel (swsusp) ===
The most straightforward approach is to directly inform the in-kernel software suspend code (swsusp) to enter a suspended state; the exact method and state depends on the level of hardware support. On modern kernels, writing appropriate strings to {{ic|/sys/power/state}} is the primary mechanism to trigger this suspend.
See [http://www.mjmwired.net/kernel/Documentation/power/states.txt kernel documentation] for details.
=== uswsusp ===
The uswsusp ('Userspace Software Suspend') provides ''s2ram'', a wrapper around the kernel's suspend-to-RAM mechanism, which performs some graphics adapter manipulations from userspace before suspending and after resuming.
See main article [[Uswsusp]].
=== tuxonice ===
TuxOnIce is a fork of the kernel implementation of suspend/resume that provides kernel patches to improve the default implementation. It requires a custom kernel to achieve this purpose.
See main article [[TuxOnIce]].
== High level interfaces ==
Note that the end goal of these packages is to provide binaries/scripts that can be invoked to perform suspend/resume. Actually hooking them up to power buttons or menu clicks or laptop lid events is left to other mechanisms. To automatically suspend/resume on certain power events, such as laptop lid close or battery depletion percentage, you may want to look into running [[Acpid]].
=== systemd ===
[[systemd]] provides native commands for suspend, hibernate and a hybrid suspend, see [[Power Management#Power management with systemd]] for details.
See [[Power Management#Sleep hooks]] for additional information on configuring suspend/resume hooks. Also see {{ic|man systemctl}}, {{ic|man systemd-sleep}}, and {{ic|man systemd.special}}.
=== pm-utils ===
pm-utils is a set of shell scripts that encapsulate the backend's suspend/resume functionality. It comes with a set of pre- and post-suspend tweaks and various hooks to customize the process.
See main article [[pm-utils]].
== Troubleshooting ==
=== ACPI_OS_NAME ===
You might want to tweak your '''DSDT table''' to make it work. See [[DSDT]] article

Revision as of 20:49, 27 July 2013