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_ADVANCED_DEBUG
  31         bool "Extra PM attributes in sysfs for low-level debugging/testing"
  32         depends on PM_DEBUG
  33         default n
  34         ---help---
  35         Add extra sysfs attributes allowing one to access some Power Management
  36         fields of device objects from user space.  If you are not a kernel
  37         developer interested in debugging/testing Power Management, say "no".
  38
  39 config PM_VERBOSE
  40         bool "Verbose Power Management debugging"
  41         depends on PM_DEBUG
  42         default n
  43         ---help---
  44         This option enables verbose messages from the Power Management code.
  45
  46 config CAN_PM_TRACE
  47         def_bool y
  48         depends on PM_DEBUG && PM_SLEEP && EXPERIMENTAL
  49
  50 config PM_TRACE
  51         bool
  52         help
  53           This enables code to save the last PM event point across
  54           reboot. The architecture needs to support this, x86 for
  55           example does by saving things in the RTC, see below.
  56
  57           The architecture specific code must provide the extern
  58           functions from <linux/resume-trace.h> as well as the
  59           <asm/resume-trace.h> header with a TRACE_RESUME() macro.
  60
  61           The way the information is presented is architecture-
  62           dependent, x86 will print the information during a
  63           late_initcall.
  64
  65 config PM_TRACE_RTC
  66         bool "Suspend/resume event tracing"
  67         depends on CAN_PM_TRACE
  68         depends on X86
  69         select PM_TRACE
  70         default n
  71         ---help---
  72         This enables some cheesy code to save the last PM event point in the
  73         RTC across reboots, so that you can debug a machine that just hangs
  74         during suspend (or more commonly, during resume).
  75
  76         To use this debugging feature you should attempt to suspend the
  77         machine, reboot it and then run
  78
  79                 dmesg -s 1000000 | grep 'hash matches'
  80
  81         CAUTION: this option will cause your machine's real-time clock to be
  82         set to an invalid time after a resume.
  83
  84 config PM_SLEEP_SMP
  85         bool
  86         depends on SMP
  87         depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE
  88         depends on PM_SLEEP
  89         select HOTPLUG
  90         select HOTPLUG_CPU
  91         default y
  92
  93 config PM_SLEEP
  94         bool
  95         depends on SUSPEND || HIBERNATION || XEN_SAVE_RESTORE
  96         default y
  97
  98 config PM_SLEEP_ADVANCED_DEBUG
  99         bool
 100         depends on PM_ADVANCED_DEBUG
 101         default n
 102
 103 config SUSPEND
 104         bool "Suspend to RAM and standby"
 105         depends on PM && ARCH_SUSPEND_POSSIBLE
 106         default y
 107         ---help---
 108           Allow the system to enter sleep states in which main memory is
 109           powered and thus its contents are preserved, such as the
 110           suspend-to-RAM state (e.g. the ACPI S3 state).
 111
 112 config PM_TEST_SUSPEND
 113         bool "Test suspend/resume and wakealarm during bootup"
 114         depends on SUSPEND && PM_DEBUG && RTC_CLASS=y
 115         ---help---
 116         This option will let you suspend your machine during bootup, and
 117         make it wake up a few seconds later using an RTC wakeup alarm.
 118         Enable this with a kernel parameter like "test_suspend=mem".
 119
 120         You probably want to have your system's RTC driver statically
 121         linked, ensuring that it's available when this test runs.
 122
 123 config SUSPEND_FREEZER
 124         bool "Enable freezer for suspend to RAM/standby" \
 125                 if ARCH_WANTS_FREEZER_CONTROL || BROKEN
 126         depends on SUSPEND
 127         default y
 128         help
 129           This allows you to turn off the freezer for suspend. If this is
 130           done, no tasks are frozen for suspend to RAM/standby.
 131
 132           Turning OFF this setting is NOT recommended! If in doubt, say Y.
 133
 134 config HIBERNATION
 135         bool "Hibernation (aka 'suspend to disk')"
 136         depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
 137         select LZO_COMPRESS
 138         select LZO_DECOMPRESS
 139         ---help---
 140           Enable the suspend to disk (STD) functionality, which is usually
 141           called "hibernation" in user interfaces.  STD checkpoints the
 142           system and powers it off; and restores that checkpoint on reboot.
 143
 144           You can suspend your machine with 'echo disk > /sys/power/state'
 145           after placing resume=/dev/swappartition on the kernel command line
 146           in your bootloader's configuration file.
 147
 148           Alternatively, you can use the additional userland tools available
 149           from <http://suspend.sf.net>.
 150
 151           In principle it does not require ACPI or APM, although for example
 152           ACPI will be used for the final steps when it is available.  One
 153           of the reasons to use software suspend is that the firmware hooks
 154           for suspend states like suspend-to-RAM (STR) often don't work very
 155           well with Linux.
 156
 157           It creates an image which is saved in your active swap. Upon the next
 158           boot, pass the 'resume=/dev/swappartition' argument to the kernel to
 159           have it detect the saved image, restore memory state from it, and
 160           continue to run as before. If you do not want the previous state to
 161           be reloaded, then use the 'noresume' kernel command line argument.
 162           Note, however, that fsck will be run on your filesystems and you will
 163           need to run mkswap against the swap partition used for the suspend.
 164
 165           It also works with swap files to a limited extent (for details see
 166           <file:Documentation/power/swsusp-and-swap-files.txt>).
 167
 168           Right now you may boot without resuming and resume later but in the
 169           meantime you cannot use the swap partition(s)/file(s) involved in
 170           suspending.  Also in this case you must not use the filesystems
 171           that were mounted before the suspend.  In particular, you MUST NOT
 172           MOUNT any journaled filesystems mounted before the suspend or they
 173           will get corrupted in a nasty way.
 174
 175           For more information take a look at <file:Documentation/power/swsusp.txt>.
 176
 177 config PM_STD_PARTITION
 178         string "Default resume partition"
 179         depends on HIBERNATION
 180         default ""
 181         ---help---
 182           The default resume partition is the partition that the suspend-
 183           to-disk implementation will look for a suspended disk image.
 184
 185           The partition specified here will be different for almost every user.
 186           It should be a valid swap partition (at least for now) that is turned
 187           on before suspending.
 188
 189           The partition specified can be overridden by specifying:
 190
 191                 resume=/dev/<other device>
 192
 193           which will set the resume partition to the device specified.
 194
 195           Note there is currently not a way to specify which device to save the
 196           suspended image to. It will simply pick the first available swap
 197           device.
 198
 199 config APM_EMULATION
 200         tristate "Advanced Power Management Emulation"
 201         depends on PM && SYS_SUPPORTS_APM_EMULATION
 202         help
 203           APM is a BIOS specification for saving power using several different
 204           techniques. This is mostly useful for battery powered laptops with
 205           APM compliant BIOSes. If you say Y here, the system time will be
 206           reset after a RESUME operation, the /proc/apm device will provide
 207           battery status information, and user-space programs will receive
 208           notification of APM "events" (e.g. battery status change).
 209
 210           In order to use APM, you will need supporting software. For location
 211           and more information, read <file:Documentation/power/pm.txt> and the
 212           Battery Powered Linux mini-HOWTO, available from
 213           <http://www.tldp.org/docs.html#howto>.
 214
 215           This driver does not spin down disk drives (see the hdparm(8)
 216           manpage ("man 8 hdparm") for that), and it doesn't turn off
 217           VESA-compliant "green" monitors.
 218
 219           Generally, if you don't have a battery in your machine, there isn't
 220           much point in using this driver and you should say N. If you get
 221           random kernel OOPSes or reboots that don't seem to be related to
 222           anything, try disabling/enabling this option (or disabling/enabling
 223           APM in your BIOS).
 224
 225 config PM_RUNTIME
 226         bool "Run-time PM core functionality"
 227         depends on PM
 228         ---help---
 229           Enable functionality allowing I/O devices to be put into energy-saving
 230           (low power) states at run time (or autosuspended) after a specified
 231           period of inactivity and woken up in response to a hardware-generated
 232           wake-up event or a driver's request.
 233
 234           Hardware support is generally required for this functionality to work
 235           and the bus type drivers of the buses the devices are on are
 236           responsible for the actual handling of the autosuspend requests and
 237           wake-up events.
 238
 239 config PM_OPS
 240         bool
 241         depends on PM_SLEEP || PM_RUNTIME
 242         default y
 243
 244 config ARCH_HAS_OPP
 245         bool
 246
 247 config PM_OPP
 248         bool "Operating Performance Point (OPP) Layer library"
 249         depends on PM
 250         depends on ARCH_HAS_OPP
 251         ---help---
 252           SOCs have a standard set of tuples consisting of frequency and
 253           voltage pairs that the device will support per voltage domain. This
 254           is called Operating Performance Point or OPP. The actual definitions
 255           of OPP varies over silicon within the same family of devices.
 256
 257           OPP layer organizes the data internally using device pointers
 258           representing individual voltage domains and provides SOC
 259           implementations a ready to use framework to manage OPPs.
 260           For more information, read <file:Documentation/power/opp.txt>