diff options
author | Dmitry Torokhov <dtor@insightbb.com> | 2006-12-08 01:07:56 -0500 |
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committer | Dmitry Torokhov <dtor@insightbb.com> | 2006-12-08 01:07:56 -0500 |
commit | bef986502fa398b1785a3979b1aa17cd902d3527 (patch) | |
tree | b59c1afe7b1dfcc001b86e54863f550d7ddc8c34 /Documentation/power/userland-swsusp.txt | |
parent | 4bdbd2807deeccc0793d57fb5120d7a53f2c0b3c (diff) | |
parent | c99767974ebd2a719d849fdeaaa1674456f5283f (diff) |
Merge rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
Conflicts:
drivers/usb/input/hid.h
Diffstat (limited to 'Documentation/power/userland-swsusp.txt')
-rw-r--r-- | Documentation/power/userland-swsusp.txt | 64 |
1 files changed, 51 insertions, 13 deletions
diff --git a/Documentation/power/userland-swsusp.txt b/Documentation/power/userland-swsusp.txt index 64755e9285db..000556c932e9 100644 --- a/Documentation/power/userland-swsusp.txt +++ b/Documentation/power/userland-swsusp.txt | |||
@@ -9,9 +9,8 @@ done it already. | |||
9 | Now, to use the userland interface for software suspend you need special | 9 | Now, to use the userland interface for software suspend you need special |
10 | utilities that will read/write the system memory snapshot from/to the | 10 | utilities that will read/write the system memory snapshot from/to the |
11 | kernel. Such utilities are available, for example, from | 11 | kernel. Such utilities are available, for example, from |
12 | <http://www.sisk.pl/kernel/utilities/suspend>. You may want to have | 12 | <http://suspend.sourceforge.net>. You may want to have a look at them if you |
13 | a look at them if you are going to develop your own suspend/resume | 13 | are going to develop your own suspend/resume utilities. |
14 | utilities. | ||
15 | 14 | ||
16 | The interface consists of a character device providing the open(), | 15 | The interface consists of a character device providing the open(), |
17 | release(), read(), and write() operations as well as several ioctl() | 16 | release(), read(), and write() operations as well as several ioctl() |
@@ -21,9 +20,9 @@ be read from /sys/class/misc/snapshot/dev. | |||
21 | 20 | ||
22 | The device can be open either for reading or for writing. If open for | 21 | The device can be open either for reading or for writing. If open for |
23 | reading, it is considered to be in the suspend mode. Otherwise it is | 22 | reading, it is considered to be in the suspend mode. Otherwise it is |
24 | assumed to be in the resume mode. The device cannot be open for reading | 23 | assumed to be in the resume mode. The device cannot be open for simultaneous |
25 | and writing. It is also impossible to have the device open more than once | 24 | reading and writing. It is also impossible to have the device open more than |
26 | at a time. | 25 | once at a time. |
27 | 26 | ||
28 | The ioctl() commands recognized by the device are: | 27 | The ioctl() commands recognized by the device are: |
29 | 28 | ||
@@ -69,9 +68,46 @@ SNAPSHOT_FREE_SWAP_PAGES - free all swap pages allocated with | |||
69 | SNAPSHOT_SET_SWAP_FILE - set the resume partition (the last ioctl() argument | 68 | SNAPSHOT_SET_SWAP_FILE - set the resume partition (the last ioctl() argument |
70 | should specify the device's major and minor numbers in the old | 69 | should specify the device's major and minor numbers in the old |
71 | two-byte format, as returned by the stat() function in the .st_rdev | 70 | two-byte format, as returned by the stat() function in the .st_rdev |
72 | member of the stat structure); it is recommended to always use this | 71 | member of the stat structure) |
73 | call, because the code to set the resume partition could be removed from | 72 | |
74 | future kernels | 73 | SNAPSHOT_SET_SWAP_AREA - set the resume partition and the offset (in <PAGE_SIZE> |
74 | units) from the beginning of the partition at which the swap header is | ||
75 | located (the last ioctl() argument should point to a struct | ||
76 | resume_swap_area, as defined in kernel/power/power.h, containing the | ||
77 | resume device specification, as for the SNAPSHOT_SET_SWAP_FILE ioctl(), | ||
78 | and the offset); for swap partitions the offset is always 0, but it is | ||
79 | different to zero for swap files (please see | ||
80 | Documentation/swsusp-and-swap-files.txt for details). | ||
81 | The SNAPSHOT_SET_SWAP_AREA ioctl() is considered as a replacement for | ||
82 | SNAPSHOT_SET_SWAP_FILE which is regarded as obsolete. It is | ||
83 | recommended to always use this call, because the code to set the resume | ||
84 | partition may be removed from future kernels | ||
85 | |||
86 | SNAPSHOT_S2RAM - suspend to RAM; using this call causes the kernel to | ||
87 | immediately enter the suspend-to-RAM state, so this call must always | ||
88 | be preceded by the SNAPSHOT_FREEZE call and it is also necessary | ||
89 | to use the SNAPSHOT_UNFREEZE call after the system wakes up. This call | ||
90 | is needed to implement the suspend-to-both mechanism in which the | ||
91 | suspend image is first created, as though the system had been suspended | ||
92 | to disk, and then the system is suspended to RAM (this makes it possible | ||
93 | to resume the system from RAM if there's enough battery power or restore | ||
94 | its state on the basis of the saved suspend image otherwise) | ||
95 | |||
96 | SNAPSHOT_PMOPS - enable the usage of the pmops->prepare, pmops->enter and | ||
97 | pmops->finish methods (the in-kernel swsusp knows these as the "platform | ||
98 | method") which are needed on many machines to (among others) speed up | ||
99 | the resume by letting the BIOS skip some steps or to let the system | ||
100 | recognise the correct state of the hardware after the resume (in | ||
101 | particular on many machines this ensures that unplugged AC | ||
102 | adapters get correctly detected and that kacpid does not run wild after | ||
103 | the resume). The last ioctl() argument can take one of the three | ||
104 | values, defined in kernel/power/power.h: | ||
105 | PMOPS_PREPARE - make the kernel carry out the | ||
106 | pm_ops->prepare(PM_SUSPEND_DISK) operation | ||
107 | PMOPS_ENTER - make the kernel power off the system by calling | ||
108 | pm_ops->enter(PM_SUSPEND_DISK) | ||
109 | PMOPS_FINISH - make the kernel carry out the | ||
110 | pm_ops->finish(PM_SUSPEND_DISK) operation | ||
75 | 111 | ||
76 | The device's read() operation can be used to transfer the snapshot image from | 112 | The device's read() operation can be used to transfer the snapshot image from |
77 | the kernel. It has the following limitations: | 113 | the kernel. It has the following limitations: |
@@ -91,10 +127,12 @@ unfreeze user space processes frozen by SNAPSHOT_UNFREEZE if they are | |||
91 | still frozen when the device is being closed). | 127 | still frozen when the device is being closed). |
92 | 128 | ||
93 | Currently it is assumed that the userland utilities reading/writing the | 129 | Currently it is assumed that the userland utilities reading/writing the |
94 | snapshot image from/to the kernel will use a swap partition, called the resume | 130 | snapshot image from/to the kernel will use a swap parition, called the resume |
95 | partition, as storage space. However, this is not really required, as they | 131 | partition, or a swap file as storage space (if a swap file is used, the resume |
96 | can use, for example, a special (blank) suspend partition or a file on a partition | 132 | partition is the partition that holds this file). However, this is not really |
97 | that is unmounted before SNAPSHOT_ATOMIC_SNAPSHOT and mounted afterwards. | 133 | required, as they can use, for example, a special (blank) suspend partition or |
134 | a file on a partition that is unmounted before SNAPSHOT_ATOMIC_SNAPSHOT and | ||
135 | mounted afterwards. | ||
98 | 136 | ||
99 | These utilities SHOULD NOT make any assumptions regarding the ordering of | 137 | These utilities SHOULD NOT make any assumptions regarding the ordering of |
100 | data within the snapshot image, except for the image header that MAY be | 138 | data within the snapshot image, except for the image header that MAY be |