kernel/power/Kconfig

   1 config PM
   2         bool "Power Management support"
   3         depends on !IA64_HP_SIM
   4         ---help---
   5           "Power Management" means that parts of your computer are shut
   6           off or put into a power conserving "sleep" mode if they are not
   7           being used.  There are two competing standards for doing this: APM
   8           and ACPI.  If you want to use either one, say Y here and then also
   9           to the requisite support below.
  10
  11           Power Management is most important for battery powered laptop
  12           computers; if you have a laptop, check out the Linux Laptop home
  13           page on the WWW at <http://www.linux-on-laptops.com/> or
  14           Tuxmobil - Linux on Mobile Computers at <http://www.tuxmobil.org/>
  15           and the Battery Powered Linux mini-HOWTO, available from
  16           <http://www.tldp.org/docs.html#howto>.
  17
  18           Note that, even if you say N here, Linux on the x86 architecture
  19           will issue the hlt instruction if nothing is to be done, thereby
  20           sending the processor to sleep and saving power.
  21
  22 config PM_LEGACY
  23         bool "Legacy Power Management API (DEPRECATED)"
  24         depends on PM
  25         default n
  26         ---help---
  27            Support for pm_register() and friends.  This old API is obsoleted
  28            by the driver model.
  29
  30            If unsure, say N.
  31
  32 config PM_DEBUG
  33         bool "Power Management Debug Support"
  34         depends on PM
  35         ---help---
  36         This option enables various debugging support in the Power Management
  37         code. This is helpful when debugging and reporting PM bugs, like
  38         suspend support.
  39
  40 config PM_VERBOSE
  41         bool "Verbose Power Management debugging"
  42         depends on PM_DEBUG
  43         default n
  44         ---help---
  45         This option enables verbose messages from the Power Management code.
  46
  47 config CAN_PM_TRACE
  48         def_bool y
  49         depends on PM_DEBUG && PM_SLEEP && EXPERIMENTAL
  50
  51 config PM_TRACE
  52         bool
  53         help
  54           This enables code to save the last PM event point across
  55           reboot. The architecture needs to support this, x86 for
  56           example does by saving things in the RTC, see below.
  57
  58           The architecture specific code must provide the extern
  59           functions from <linux/resume-trace.h> as well as the
  60           <asm/resume-trace.h> header with a TRACE_RESUME() macro.
  61
  62           The way the information is presented is architecture-
  63           dependent, x86 will print the information during a
  64           late_initcall.
  65
  66 config PM_TRACE_RTC
  67         bool "Suspend/resume event tracing"
  68         depends on CAN_PM_TRACE
  69         depends on X86
  70         select PM_TRACE
  71         default n
  72         ---help---
  73         This enables some cheesy code to save the last PM event point in the
  74         RTC across reboots, so that you can debug a machine that just hangs
  75         during suspend (or more commonly, during resume).
  76
  77         To use this debugging feature you should attempt to suspend the machine,
  78         then reboot it, then run
  79
  80                 dmesg -s 1000000 | grep 'hash matches'
  81
  82         CAUTION: this option will cause your machine's real-time clock to be
  83         set to an invalid time after a resume.
  84
  85 config PM_SLEEP_SMP
  86         bool
  87         depends on SMP
  88         depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE
  89         depends on PM_SLEEP
  90         select HOTPLUG_CPU
  91         default y
  92
  93 config PM_SLEEP
  94         bool
  95         depends on SUSPEND || HIBERNATION
  96         default y
  97
  98 config SUSPEND
  99         bool "Suspend to RAM and standby"
 100         depends on PM && ARCH_SUSPEND_POSSIBLE
 101         default y
 102         ---help---
 103           Allow the system to enter sleep states in which main memory is
 104           powered and thus its contents are preserved, such as the
 105           suspend-to-RAM state (e.g. the ACPI S3 state).
 106
 107 config SUSPEND_FREEZER
 108         bool "Enable freezer for suspend to RAM/standby" \
 109                 if ARCH_WANTS_FREEZER_CONTROL || BROKEN
 110         depends on SUSPEND
 111         default y
 112         help
 113           This allows you to turn off the freezer for suspend. If this is
 114           done, no tasks are frozen for suspend to RAM/standby.
 115
 116           Turning OFF this setting is NOT recommended! If in doubt, say Y.
 117
 118 config HIBERNATION
 119         bool "Hibernation (aka 'suspend to disk')"
 120         depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
 121         ---help---
 122           Enable the suspend to disk (STD) functionality, which is usually
 123           called "hibernation" in user interfaces.  STD checkpoints the
 124           system and powers it off; and restores that checkpoint on reboot.
 125
 126           You can suspend your machine with 'echo disk > /sys/power/state'.
 127           Alternatively, you can use the additional userland tools available
 128           from <http://suspend.sf.net>.
 129
 130           In principle it does not require ACPI or APM, although for example
 131           ACPI will be used for the final steps when it is available.  One
 132           of the reasons to use software suspend is that the firmware hooks
 133           for suspend states like suspend-to-RAM (STR) often don't work very
 134           well with Linux.
 135
 136           It creates an image which is saved in your active swap. Upon the next
 137           boot, pass the 'resume=/dev/swappartition' argument to the kernel to
 138           have it detect the saved image, restore memory state from it, and
 139           continue to run as before. If you do not want the previous state to
 140           be reloaded, then use the 'noresume' kernel command line argument.
 141           Note, however, that fsck will be run on your filesystems and you will
 142           need to run mkswap against the swap partition used for the suspend.
 143
 144           It also works with swap files to a limited extent (for details see
 145           <file:Documentation/power/swsusp-and-swap-files.txt>).
 146
 147           Right now you may boot without resuming and resume later but in the
 148           meantime you cannot use the swap partition(s)/file(s) involved in
 149           suspending.  Also in this case you must not use the filesystems
 150           that were mounted before the suspend.  In particular, you MUST NOT
 151           MOUNT any journaled filesystems mounted before the suspend or they
 152           will get corrupted in a nasty way.
 153
 154           For more information take a look at <file:Documentation/power/swsusp.txt>.
 155
 156 config PM_STD_PARTITION
 157         string "Default resume partition"
 158         depends on HIBERNATION
 159         default ""
 160         ---help---
 161           The default resume partition is the partition that the suspend-
 162           to-disk implementation will look for a suspended disk image.
 163
 164           The partition specified here will be different for almost every user.
 165           It should be a valid swap partition (at least for now) that is turned
 166           on before suspending.
 167
 168           The partition specified can be overridden by specifying:
 169
 170                 resume=/dev/<other device>
 171
 172           which will set the resume partition to the device specified.
 173
 174           Note there is currently not a way to specify which device to save the
 175           suspended image to. It will simply pick the first available swap
 176           device.
 177
 178 config APM_EMULATION
 179         tristate "Advanced Power Management Emulation"
 180         depends on PM && SYS_SUPPORTS_APM_EMULATION
 181         help
 182           APM is a BIOS specification for saving power using several different
 183           techniques. This is mostly useful for battery powered laptops with
 184           APM compliant BIOSes. If you say Y here, the system time will be
 185           reset after a RESUME operation, the /proc/apm device will provide
 186           battery status information, and user-space programs will receive
 187           notification of APM "events" (e.g. battery status change).
 188
 189           In order to use APM, you will need supporting software. For location
 190           and more information, read <file:Documentation/pm.txt> and the
 191           Battery Powered Linux mini-HOWTO, available from
 192           <http://www.tldp.org/docs.html#howto>.
 193
 194           This driver does not spin down disk drives (see the hdparm(8)
 195           manpage ("man 8 hdparm") for that), and it doesn't turn off
 196           VESA-compliant "green" monitors.
 197
 198           Generally, if you don't have a battery in your machine, there isn't
 199           much point in using this driver and you should say N. If you get
 200           random kernel OOPSes or reboots that don't seem to be related to
 201           anything, try disabling/enabling this option (or disabling/enabling
 202           APM in your BIOS).