diff options
Diffstat (limited to 'Documentation/power/states.txt')
-rw-r--r-- | Documentation/power/states.txt | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/Documentation/power/states.txt b/Documentation/power/states.txt index 0931a330d362..34800cc521bf 100644 --- a/Documentation/power/states.txt +++ b/Documentation/power/states.txt | |||
@@ -62,17 +62,18 @@ setup via another operating system for it to use. Despite the | |||
62 | inconvenience, this method requires minimal work by the kernel, since | 62 | inconvenience, this method requires minimal work by the kernel, since |
63 | the firmware will also handle restoring memory contents on resume. | 63 | the firmware will also handle restoring memory contents on resume. |
64 | 64 | ||
65 | If the kernel is responsible for persistently saving state, a mechanism | 65 | For suspend-to-disk, a mechanism called swsusp called 'swsusp' (Swap |
66 | called 'swsusp' (Swap Suspend) is used to write memory contents to | 66 | Suspend) is used to write memory contents to free swap space. |
67 | free swap space. swsusp has some restrictive requirements, but should | 67 | swsusp has some restrictive requirements, but should work in most |
68 | work in most cases. Some, albeit outdated, documentation can be found | 68 | cases. Some, albeit outdated, documentation can be found in |
69 | in Documentation/power/swsusp.txt. | 69 | Documentation/power/swsusp.txt. Alternatively, userspace can do most |
70 | of the actual suspend to disk work, see userland-swsusp.txt. | ||
70 | 71 | ||
71 | Once memory state is written to disk, the system may either enter a | 72 | Once memory state is written to disk, the system may either enter a |
72 | low-power state (like ACPI S4), or it may simply power down. Powering | 73 | low-power state (like ACPI S4), or it may simply power down. Powering |
73 | down offers greater savings, and allows this mechanism to work on any | 74 | down offers greater savings, and allows this mechanism to work on any |
74 | system. However, entering a real low-power state allows the user to | 75 | system. However, entering a real low-power state allows the user to |
75 | trigger wake up events (e.g. pressing a key or opening a laptop lid). | 76 | trigger wake up events (e.g. pressing a key or opening a laptop lid). |
76 | 77 | ||
77 | A transition from Suspend-to-Disk to the On state should take about 30 | 78 | A transition from Suspend-to-Disk to the On state should take about 30 |
78 | seconds, though it's typically a bit more with the current | 79 | seconds, though it's typically a bit more with the current |