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
  78         machine, reboot it and 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           after placing resume=/dev/swappartition on the kernel command line
 128           in your bootloader's configuration file.
 129
 130           Alternatively, you can use the additional userland tools available
 131           from <http://suspend.sf.net>.
 132
 133           In principle it does not require ACPI or APM, although for example
 134           ACPI will be used for the final steps when it is available.  One
 135           of the reasons to use software suspend is that the firmware hooks
 136           for suspend states like suspend-to-RAM (STR) often don't work very
 137           well with Linux.
 138
 139           It creates an image which is saved in your active swap. Upon the next
 140           boot, pass the 'resume=/dev/swappartition' argument to the kernel to
 141           have it detect the saved image, restore memory state from it, and
 142           continue to run as before. If you do not want the previous state to
 143           be reloaded, then use the 'noresume' kernel command line argument.
 144           Note, however, that fsck will be run on your filesystems and you will
 145           need to run mkswap against the swap partition used for the suspend.
 146
 147           It also works with swap files to a limited extent (for details see
 148           <file:Documentation/power/swsusp-and-swap-files.txt>).
 149
 150           Right now you may boot without resuming and resume later but in the
 151           meantime you cannot use the swap partition(s)/file(s) involved in
 152           suspending.  Also in this case you must not use the filesystems
 153           that were mounted before the suspend.  In particular, you MUST NOT
 154           MOUNT any journaled filesystems mounted before the suspend or they
 155           will get corrupted in a nasty way.
 156
 157           For more information take a look at <file:Documentation/power/swsusp.txt>.
 158
 159 config PM_STD_PARTITION
 160         string "Default resume partition"
 161         depends on HIBERNATION
 162         default ""
 163         ---help---
 164           The default resume partition is the partition that the suspend-
 165           to-disk implementation will look for a suspended disk image.
 166
 167           The partition specified here will be different for almost every user.
 168           It should be a valid swap partition (at least for now) that is turned
 169           on before suspending.
 170
 171           The partition specified can be overridden by specifying:
 172
 173                 resume=/dev/<other device>
 174
 175           which will set the resume partition to the device specified.
 176
 177           Note there is currently not a way to specify which device to save the
 178           suspended image to. It will simply pick the first available swap
 179           device.
 180
 181 config APM_EMULATION
 182         tristate "Advanced Power Management Emulation"
 183         depends on PM && SYS_SUPPORTS_APM_EMULATION
 184         help
 185           APM is a BIOS specification for saving power using several different
 186           techniques. This is mostly useful for battery powered laptops with
 187           APM compliant BIOSes. If you say Y here, the system time will be
 188           reset after a RESUME operation, the /proc/apm device will provide
 189           battery status information, and user-space programs will receive
 190           notification of APM "events" (e.g. battery status change).
 191
 192           In order to use APM, you will need supporting software. For location
 193           and more information, read <file:Documentation/pm.txt> and the
 194           Battery Powered Linux mini-HOWTO, available from
 195           <http://www.tldp.org/docs.html#howto>.
 196
 197           This driver does not spin down disk drives (see the hdparm(8)
 198           manpage ("man 8 hdparm") for that), and it doesn't turn off
 199           VESA-compliant "green" monitors.
 200
 201           Generally, if you don't have a battery in your machine, there isn't
 202           much point in using this driver and you should say N. If you get
 203           random kernel OOPSes or reboots that don't seem to be related to
 204           anything, try disabling/enabling this option (or disabling/enabling
 205           APM in your BIOS).