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Hibernation: Rework platform support ioctls (rev. 2)

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Modify the hibernation userland interface by adding two new ioctls to it,
SNAPSHOT_PLATFORM_SUPPORT and SNAPSHOT_POWER_OFF, that can be used,
respectively, to switch the hibernation platform support on/off and to make the
kernel transition the system to the hibernation state (eg. ACPI S4) using the
platform (eg. ACPI) driver.

These ioctls are intended to replace the misdesigned SNAPSHOT_PMOPS ioctl,
which from now is regarded as obsolete and will be removed in the future.

Signed-off-by: Rafael J. Wysocki <[email protected]>
Acked-by: Pavel Machek <[email protected]>
Signed-off-by: Len Brown <[email protected]>
This commit is contained in:
Rafael J. Wysocki 2007-10-26 01:01:10 +02:00 • committed by Len Brown
commit eb57c1cf05
3 changed files with 38 additions and 34 deletions
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24
Documentation/power/userland-swsusp.txt
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@ -85,6 +85,12 @@ SNAPSHOT_SET_SWAP_AREA - set the resume partition and the offset (in <PAGE_SIZE>
recommended to always use this call, because the code to set the resume
partition may be removed from future kernels
SNAPSHOT_PLATFORM_SUPPORT - enable/disable the hibernation platform support,
depending on the argument value (enable, if the argument is nonzero)
SNAPSHOT_POWER_OFF - make the kernel transition the system to the hibernation
state (eg. ACPI S4) using the platform (eg. ACPI) driver
SNAPSHOT_S2RAM - suspend to RAM; using this call causes the kernel to
immediately enter the suspend-to-RAM state, so this call must always
be preceded by the SNAPSHOT_FREEZE call and it is also necessary
@ -95,24 +101,6 @@ SNAPSHOT_S2RAM - suspend to RAM; using this call causes the kernel to
to resume the system from RAM if there's enough battery power or restore
its state on the basis of the saved suspend image otherwise)
SNAPSHOT_PMOPS - enable the usage of the hibernation_ops->prepare,
hibernate_ops->enter and hibernation_ops->finish methods (the in-kernel
swsusp knows these as the "platform method") which are needed on many
machines to (among others) speed up the resume by letting the BIOS skip
some steps or to let the system recognise the correct state of the
hardware after the resume (in particular on many machines this ensures
that unplugged AC adapters get correctly detected and that kacpid does
not run wild after the resume). The last ioctl() argument can take one
of the three values, defined in kernel/power/power.h:
PMOPS_PREPARE - make the kernel carry out the
hibernation_ops->prepare() operation
PMOPS_ENTER - make the kernel power off the system by calling
hibernation_ops->enter()
PMOPS_FINISH - make the kernel carry out the
hibernation_ops->finish() operation
Note that the actual constants are misnamed because they surface
internal kernel implementation details that have changed.
The device's read() operation can be used to transfer the snapshot image from
the kernel. It has the following limitations:
- you cannot read() more than one virtual memory page at a time