config PM
bool "Power Management support"
depends on !IA64_HP_SIM
---help---
"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 <http://www.linux-on-laptops.com/> or
Tuxmobil - Linux on Mobile Computers at <http://www.tuxmobil.org/>
and the Battery Powered Linux mini-HOWTO, available from
<http://www.tldp.org/docs.html#howto>.
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
---help---
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
---help---
This option enables various debugging support in the Power Management
code. This is helpful when debugging and reporting PM bugs, like
suspend support.
config PM_VERBOSE
bool "Verbose Power Management debugging"
depends on PM_DEBUG
default n
---help---
This option enables verbose messages from the Power Management code.
config CAN_PM_TRACE
def_bool y
depends on PM_DEBUG && PM_SLEEP && EXPERIMENTAL
config PM_TRACE
bool
help
This enables code to save the last PM event point across
reboot. The architecture needs to support this, x86 for
example does by saving things in the RTC, see below.
The architecture specific code must provide the extern
functions from <linux/resume-trace.h> as well as the
<asm/resume-trace.h> header with a TRACE_RESUME() macro.
The way the information is presented is architecture-
dependent, x86 will print the information during a
late_initcall.
config PM_TRACE_RTC
bool "Suspend/resume event tracing"
depends on CAN_PM_TRACE
depends on X86
select PM_TRACE
default n
---help---
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, reboot it and 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.
config PM_SLEEP_SMP
bool
depends on SMP
depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE
depends on PM_SLEEP
select HOTPLUG_CPU
default y
config PM_SLEEP
bool
depends on SUSPEND || HIBERNATION
default y
config SUSPEND
bool "Suspend to RAM and standby"
depends on PM && ARCH_SUSPEND_POSSIBLE
default y
---help---
Allow the system to enter sleep states in which main memory is
powered and thus its contents are preserved, such as the
suspend-to-RAM state (e.g. the ACPI S3 state).
config SUSPEND_FREEZER
bool "Enable freezer for suspend to RAM/standby" \
if ARCH_WANTS_FREEZER_CONTROL || BROKEN
depends on SUSPEND
default y
help
This allows you to turn off the freezer for suspend. If this is
done, no tasks are frozen for suspend to RAM/standby.
Turning OFF this setting is NOT recommended! If in doubt, say Y.
config HIBERNATION
bool "Hibernation (aka 'suspend to disk')"
depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
---help---
Enable the suspend to disk (STD) functionality, which is usually
called "hibernation" in user interfaces. STD checkpoints the
system and powers it off; and restores that checkpoint on reboot.
You can suspend your machine with 'echo disk > /sys/power/state'
after placing resume=/dev/swappartition on the kernel command line
in your bootloader's configuration file.
Alternatively, you can use the additional userland tools available
from <http://suspend.sf.net>.
In principle it does not require ACPI or APM, although for example
ACPI will be used for the final steps when it is available. One
of the reasons to use software suspend is that the firmware hooks
for suspend states like suspend-to-RAM (STR) often don't work very
well with Linux.
It creates an image which is saved in your active swap. Upon the 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 command line argument.
Note, however, that fsck will be run on your filesystems and you will
need to run mkswap against the swap partition used for the suspend.
It also works with swap files to a limited extent (for details see
<file:Documentation/power/swsusp-and-swap-files.txt>).
Right now you may boot without resuming and resume later but in the
meantime you cannot use the swap partition(s)/file(s) involved in
suspending. Also in this case you must not use the filesystems
that were mounted before the suspend. In particular, you MUST NOT
MOUNT any journaled filesystems mounted before the suspend or they
will get corrupted in a nasty way.
For more information take a look at <file:Documentation/power/swsusp.txt>.
config PM_STD_PARTITION
string "Default resume partition"
depends on HIBERNATION
default ""
---help---
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
device.
config APM_EMULATION
tristate "Advanced Power Management Emulation"
depends on PM && SYS_SUPPORTS_APM_EMULATION
help
APM is a BIOS specification for saving power using several different
techniques. This is mostly useful for battery powered laptops with
APM compliant BIOSes. If you say Y here, the system time will be
reset after a RESUME operation, the /proc/apm device will provide
battery status information, and user-space programs will receive
notification of APM "events" (e.g. battery status change).
In order to use APM, you will need supporting software. For location
and more information, read <file:Documentation/power/pm.txt> and the
Battery Powered Linux mini-HOWTO, available from
<http://www.tldp.org/docs.html#howto>.
This driver does not spin down disk drives (see the hdparm(8)
manpage ("man 8 hdparm") for that), and it doesn't turn off
VESA-compliant "green" monitors.
Generally, if you don't have a battery in your machine, there isn't
much point in using this driver and you should say N. If you get
random kernel OOPSes or reboots that don't seem to be related to
anything, try disabling/enabling this option (or disabling/enabling
APM in your BIOS).
