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config PM
bool "Power Management support"
depends on !IA64_HP_SIM
"Power Management" means that parts of your computer are shut
off or put into a power conserving "sleep" mode if they are not
being used. There are two competing standards for doing this: APM
and ACPI. If you want to use either one, say Y here and then also
to the requisite support below.
Power Management is most important for battery powered laptop
computers; if you have a laptop, check out the Linux Laptop home
page on the WWW at <> or
Tuxmobil - Linux on Mobile Computers at <>
and the Battery Powered Linux mini-HOWTO, available from
Note that, even if you say N here, Linux on the x86 architecture
will issue the hlt instruction if nothing is to be done, thereby
sending the processor to sleep and saving power.
config PM_LEGACY
bool "Legacy Power Management API (DEPRECATED)"
depends on PM
default n
Support for pm_register() and friends. This old API is obsoleted
by the driver model.
If unsure, say N.
config PM_DEBUG
bool "Power Management Debug Support"
depends on PM
This option enables verbose debugging support in the Power Management
code. This is helpful when debugging and reporting various PM bugs,
like suspend support.
bool "Keep console(s) enabled during suspend/resume (DANGEROUS)"
depends on PM && PM_DEBUG
default n
This option turns off the console suspend mechanism that prevents
debug messages from reaching the console during the suspend/resume
operations. This may be helpful when debugging device drivers'
suspend/resume routines, but may itself lead to problems, for example
if netconsole is used.
config PM_TRACE
bool "Suspend/resume event tracing"
depends on PM && PM_DEBUG && X86_32 && EXPERIMENTAL
default n
This enables some cheesy code to save the last PM event point in the
RTC across reboots, so that you can debug a machine that just hangs
during suspend (or more commonly, during resume).
To use this debugging feature you should attempt to suspend the machine,
then reboot it, then run
dmesg -s 1000000 | grep 'hash matches'
CAUTION: this option will cause your machine's real-time clock to be
set to an invalid time after a resume.
bool "Driver model /sys/devices/.../power/state files (DEPRECATED)"
depends on PM && SYSFS
default n
The driver model started out with a sysfs file intended to provide
a userspace hook for device power management. This feature has never
worked very well, except for limited testing purposes, and so it will
be removed. It's not clear that a generic mechanism could really
handle the wide variability of device power states; any replacements
are likely to be bus or driver specific.
bool "Software Suspend"
depends on PM && SWAP && ((X86 && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP))
Enable the possibility of suspending the machine.
It doesn't need ACPI or APM.
You may suspend your machine by 'swsusp' or 'shutdown -z <time>'
(patch for sysvinit needed).
It creates an image which is saved in your active swap. Upon next
boot, pass the 'resume=/dev/swappartition' argument to the kernel to
have it detect the saved image, restore memory state from it, and
continue to run as before. If you do not want the previous state to
be reloaded, then use the 'noresume' kernel argument. However, note
that your partitions will be fsck'd and you must re-mkswap your swap
partitions. It does not work with swap files.
Right now you may boot without resuming and then later resume but
in meantime you cannot use those swap partitions/files which were
involved in suspending. Also in this case there is a risk that buffers
on disk won't match with saved ones.
For more information take a look at <file:Documentation/power/swsusp.txt>.
(For now, swsusp is incompatible with PAE aka HIGHMEM_64G on i386.
we need identity mapping for resume to work, and that is trivial
to get with 4MB pages, but less than trivial on PAE).
string "Default resume partition"
default ""
The default resume partition is the partition that the suspend-
to-disk implementation will look for a suspended disk image.
The partition specified here will be different for almost every user.
It should be a valid swap partition (at least for now) that is turned
on before suspending.
The partition specified can be overridden by specifying:
resume=/dev/<other device>
which will set the resume partition to the device specified.
Note there is currently not a way to specify which device to save the
suspended image to. It will simply pick the first available swap
depends on HOTPLUG_CPU && X86 && PM
default y