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_DEBUG
  23         bool "Power Management Debug Support"
  24         depends on PM
  25         ---help---
  26         This option enables various debugging support in the Power Management
  27         code. This is helpful when debugging and reporting PM bugs, like
  28         suspend support.
  29
  30 config PM_VERBOSE
  31         bool "Verbose Power Management debugging"
  32         depends on PM_DEBUG
  33         default n
  34         ---help---
  35         This option enables verbose messages from the Power Management code.
  36
  37 config CAN_PM_TRACE
  38         def_bool y
  39         depends on PM_DEBUG && PM_SLEEP && EXPERIMENTAL
  40
  41 config PM_TRACE
  42         bool
  43         help
  44           This enables code to save the last PM event point across
  45           reboot. The architecture needs to support this, x86 for
  46           example does by saving things in the RTC, see below.
  47
  48           The architecture specific code must provide the extern
  49           functions from <linux/resume-trace.h> as well as the
  50           <asm/resume-trace.h> header with a TRACE_RESUME() macro.
  51
  52           The way the information is presented is architecture-
  53           dependent, x86 will print the information during a
  54           late_initcall.
  55
  56 config PM_TRACE_RTC
  57         bool "Suspend/resume event tracing"
  58         depends on CAN_PM_TRACE
  59         depends on X86
  60         select PM_TRACE
  61         default n
  62         ---help---
  63         This enables some cheesy code to save the last PM event point in the
  64         RTC across reboots, so that you can debug a machine that just hangs
  65         during suspend (or more commonly, during resume).
  66
  67         To use this debugging feature you should attempt to suspend the
  68         machine, reboot it and then run
  69
  70                 dmesg -s 1000000 | grep 'hash matches'
  71
  72         CAUTION: this option will cause your machine's real-time clock to be
  73         set to an invalid time after a resume.
  74
  75 config PM_SLEEP_SMP
  76         bool
  77         depends on SMP
  78         depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE
  79         depends on PM_SLEEP
  80         select HOTPLUG_CPU
  81         default y
  82
  83 config PM_SLEEP
  84         bool
  85         depends on SUSPEND || HIBERNATION
  86         default y
  87
  88 config SUSPEND
  89         bool "Suspend to RAM and standby"
  90         depends on PM && ARCH_SUSPEND_POSSIBLE
  91         default y
  92         ---help---
  93           Allow the system to enter sleep states in which main memory is
  94           powered and thus its contents are preserved, such as the
  95           suspend-to-RAM state (e.g. the ACPI S3 state).
  96
  97 config SUSPEND_FREEZER
  98         bool "Enable freezer for suspend to RAM/standby" \
  99                 if ARCH_WANTS_FREEZER_CONTROL || BROKEN
 100         depends on SUSPEND
 101         default y
 102         help
 103           This allows you to turn off the freezer for suspend. If this is
 104           done, no tasks are frozen for suspend to RAM/standby.
 105
 106           Turning OFF this setting is NOT recommended! If in doubt, say Y.
 107
 108 config HIBERNATION
 109         bool "Hibernation (aka 'suspend to disk')"
 110         depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
 111         ---help---
 112           Enable the suspend to disk (STD) functionality, which is usually
 113           called "hibernation" in user interfaces.  STD checkpoints the
 114           system and powers it off; and restores that checkpoint on reboot.
 115
 116           You can suspend your machine with 'echo disk > /sys/power/state'
 117           after placing resume=/dev/swappartition on the kernel command line
 118           in your bootloader's configuration file.
 119
 120           Alternatively, you can use the additional userland tools available
 121           from <http://suspend.sf.net>.
 122
 123           In principle it does not require ACPI or APM, although for example
 124           ACPI will be used for the final steps when it is available.  One
 125           of the reasons to use software suspend is that the firmware hooks
 126           for suspend states like suspend-to-RAM (STR) often don't work very
 127           well with Linux.
 128
 129           It creates an image which is saved in your active swap. Upon the next
 130           boot, pass the 'resume=/dev/swappartition' argument to the kernel to
 131           have it detect the saved image, restore memory state from it, and
 132           continue to run as before. If you do not want the previous state to
 133           be reloaded, then use the 'noresume' kernel command line argument.
 134           Note, however, that fsck will be run on your filesystems and you will
 135           need to run mkswap against the swap partition used for the suspend.
 136
 137           It also works with swap files to a limited extent (for details see
 138           <file:Documentation/power/swsusp-and-swap-files.txt>).
 139
 140           Right now you may boot without resuming and resume later but in the
 141           meantime you cannot use the swap partition(s)/file(s) involved in
 142           suspending.  Also in this case you must not use the filesystems
 143           that were mounted before the suspend.  In particular, you MUST NOT
 144           MOUNT any journaled filesystems mounted before the suspend or they
 145           will get corrupted in a nasty way.
 146
 147           For more information take a look at <file:Documentation/power/swsusp.txt>.
 148
 149 config PM_STD_PARTITION
 150         string "Default resume partition"
 151         depends on HIBERNATION
 152         default ""
 153         ---help---
 154           The default resume partition is the partition that the suspend-
 155           to-disk implementation will look for a suspended disk image.
 156
 157           The partition specified here will be different for almost every user.
 158           It should be a valid swap partition (at least for now) that is turned
 159           on before suspending.
 160
 161           The partition specified can be overridden by specifying:
 162
 163                 resume=/dev/<other device>
 164
 165           which will set the resume partition to the device specified.
 166
 167           Note there is currently not a way to specify which device to save the
 168           suspended image to. It will simply pick the first available swap
 169           device.
 170
 171 config APM_EMULATION
 172         tristate "Advanced Power Management Emulation"
 173         depends on PM && SYS_SUPPORTS_APM_EMULATION
 174         help
 175           APM is a BIOS specification for saving power using several different
 176           techniques. This is mostly useful for battery powered laptops with
 177           APM compliant BIOSes. If you say Y here, the system time will be
 178           reset after a RESUME operation, the /proc/apm device will provide
 179           battery status information, and user-space programs will receive
 180           notification of APM "events" (e.g. battery status change).
 181
 182           In order to use APM, you will need supporting software. For location
 183           and more information, read <file:Documentation/power/pm.txt> and the
 184           Battery Powered Linux mini-HOWTO, available from
 185           <http://www.tldp.org/docs.html#howto>.
 186
 187           This driver does not spin down disk drives (see the hdparm(8)
 188           manpage ("man 8 hdparm") for that), and it doesn't turn off
 189           VESA-compliant "green" monitors.
 190
 191           Generally, if you don't have a battery in your machine, there isn't
 192           much point in using this driver and you should say N. If you get
 193           random kernel OOPSes or reboots that don't seem to be related to
 194           anything, try disabling/enabling this option (or disabling/enabling
 195           APM in your BIOS).