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 || XEN_SAVE_RESTORE
  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 PM_TEST_SUSPEND
  98         bool "Test suspend/resume and wakealarm during bootup"
  99         depends on SUSPEND && PM_DEBUG && RTC_LIB=y
 100         ---help---
 101         This option will let you suspend your machine during bootup, and
 102         make it wake up a few seconds later using an RTC wakeup alarm.
 103         Enable this with a kernel parameter like "test_suspend=mem".
 104
 105         You probably want to have your system's RTC driver statically
 106         linked, ensuring that it's available when this test runs.
 107
 108 config SUSPEND_FREEZER
 109         bool "Enable freezer for suspend to RAM/standby" \
 110                 if ARCH_WANTS_FREEZER_CONTROL || BROKEN
 111         depends on SUSPEND
 112         default y
 113         help
 114           This allows you to turn off the freezer for suspend. If this is
 115           done, no tasks are frozen for suspend to RAM/standby.
 116
 117           Turning OFF this setting is NOT recommended! If in doubt, say Y.
 118
 119 config HIBERNATION
 120         bool "Hibernation (aka 'suspend to disk')"
 121         depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
 122         ---help---
 123           Enable the suspend to disk (STD) functionality, which is usually
 124           called "hibernation" in user interfaces.  STD checkpoints the
 125           system and powers it off; and restores that checkpoint on reboot.
 126
 127           You can suspend your machine with 'echo disk > /sys/power/state'
 128           after placing resume=/dev/swappartition on the kernel command line
 129           in your bootloader's configuration file.
 130
 131           Alternatively, you can use the additional userland tools available
 132           from <http://suspend.sf.net>.
 133
 134           In principle it does not require ACPI or APM, although for example
 135           ACPI will be used for the final steps when it is available.  One
 136           of the reasons to use software suspend is that the firmware hooks
 137           for suspend states like suspend-to-RAM (STR) often don't work very
 138           well with Linux.
 139
 140           It creates an image which is saved in your active swap. Upon the next
 141           boot, pass the 'resume=/dev/swappartition' argument to the kernel to
 142           have it detect the saved image, restore memory state from it, and
 143           continue to run as before. If you do not want the previous state to
 144           be reloaded, then use the 'noresume' kernel command line argument.
 145           Note, however, that fsck will be run on your filesystems and you will
 146           need to run mkswap against the swap partition used for the suspend.
 147
 148           It also works with swap files to a limited extent (for details see
 149           <file:Documentation/power/swsusp-and-swap-files.txt>).
 150
 151           Right now you may boot without resuming and resume later but in the
 152           meantime you cannot use the swap partition(s)/file(s) involved in
 153           suspending.  Also in this case you must not use the filesystems
 154           that were mounted before the suspend.  In particular, you MUST NOT
 155           MOUNT any journaled filesystems mounted before the suspend or they
 156           will get corrupted in a nasty way.
 157
 158           For more information take a look at <file:Documentation/power/swsusp.txt>.
 159
 160 config PM_STD_PARTITION
 161         string "Default resume partition"
 162         depends on HIBERNATION
 163         default ""
 164         ---help---
 165           The default resume partition is the partition that the suspend-
 166           to-disk implementation will look for a suspended disk image.
 167
 168           The partition specified here will be different for almost every user.
 169           It should be a valid swap partition (at least for now) that is turned
 170           on before suspending.
 171
 172           The partition specified can be overridden by specifying:
 173
 174                 resume=/dev/<other device>
 175
 176           which will set the resume partition to the device specified.
 177
 178           Note there is currently not a way to specify which device to save the
 179           suspended image to. It will simply pick the first available swap
 180           device.
 181
 182 config APM_EMULATION
 183         tristate "Advanced Power Management Emulation"
 184         depends on PM && SYS_SUPPORTS_APM_EMULATION
 185         help
 186           APM is a BIOS specification for saving power using several different
 187           techniques. This is mostly useful for battery powered laptops with
 188           APM compliant BIOSes. If you say Y here, the system time will be
 189           reset after a RESUME operation, the /proc/apm device will provide
 190           battery status information, and user-space programs will receive
 191           notification of APM "events" (e.g. battery status change).
 192
 193           In order to use APM, you will need supporting software. For location
 194           and more information, read <file:Documentation/power/pm.txt> and the
 195           Battery Powered Linux mini-HOWTO, available from
 196           <http://www.tldp.org/docs.html#howto>.
 197
 198           This driver does not spin down disk drives (see the hdparm(8)
 199           manpage ("man 8 hdparm") for that), and it doesn't turn off
 200           VESA-compliant "green" monitors.
 201
 202           Generally, if you don't have a battery in your machine, there isn't
 203           much point in using this driver and you should say N. If you get
 204           random kernel OOPSes or reboots that don't seem to be related to
 205           anything, try disabling/enabling this option (or disabling/enabling
 206           APM in your BIOS).