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-rw-r--r--Documentation/power/states.txt13
1 files changed, 7 insertions, 6 deletions
diff --git a/Documentation/power/states.txt b/Documentation/power/states.txt
index 0931a330d362..34800cc521bf 100644
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@@ -62,17 +62,18 @@ setup via another operating system for it to use. Despite the
62inconvenience, this method requires minimal work by the kernel, since 62inconvenience, this method requires minimal work by the kernel, since
63the firmware will also handle restoring memory contents on resume. 63the firmware will also handle restoring memory contents on resume.
64 64
65If the kernel is responsible for persistently saving state, a mechanism 65For suspend-to-disk, a mechanism called swsusp called 'swsusp' (Swap
66called 'swsusp' (Swap Suspend) is used to write memory contents to 66Suspend) is used to write memory contents to free swap space.
67free swap space. swsusp has some restrictive requirements, but should 67swsusp has some restrictive requirements, but should work in most
68work in most cases. Some, albeit outdated, documentation can be found 68cases. Some, albeit outdated, documentation can be found in
69in Documentation/power/swsusp.txt. 69Documentation/power/swsusp.txt. Alternatively, userspace can do most
70of the actual suspend to disk work, see userland-swsusp.txt.
70 71
71Once memory state is written to disk, the system may either enter a 72Once memory state is written to disk, the system may either enter a
72low-power state (like ACPI S4), or it may simply power down. Powering 73low-power state (like ACPI S4), or it may simply power down. Powering
73down offers greater savings, and allows this mechanism to work on any 74down offers greater savings, and allows this mechanism to work on any
74system. However, entering a real low-power state allows the user to 75system. However, entering a real low-power state allows the user to
75trigger wake up events (e.g. pressing a key or opening a laptop lid). 76trigger wake up events (e.g. pressing a key or opening a laptop lid).
76 77
77A transition from Suspend-to-Disk to the On state should take about 30 78A transition from Suspend-to-Disk to the On state should take about 30
78seconds, though it's typically a bit more with the current 79seconds, though it's typically a bit more with the current