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 PM_TRACE
  48         bool "Suspend/resume event tracing"
  49         depends on PM_DEBUG && X86 && PM_SLEEP && EXPERIMENTAL
  50         default n
  51         ---help---
  52         This enables some cheesy code to save the last PM event point in the
  53         RTC across reboots, so that you can debug a machine that just hangs
  54         during suspend (or more commonly, during resume).
  55
  56         To use this debugging feature you should attempt to suspend the machine,
  57         then reboot it, then run
  58
  59                 dmesg -s 1000000 | grep 'hash matches'
  60
  61         CAUTION: this option will cause your machine's real-time clock to be
  62         set to an invalid time after a resume.
  63
  64 config PM_SLEEP_SMP
  65         bool
  66         depends on SUSPEND_SMP_POSSIBLE || HIBERNATION_SMP_POSSIBLE
  67         depends on PM_SLEEP
  68         select HOTPLUG_CPU
  69         default y
  70
  71 config PM_SLEEP
  72         bool
  73         depends on SUSPEND || HIBERNATION
  74         default y
  75
  76 config SUSPEND_UP_POSSIBLE
  77         bool
  78         depends on (X86 && !X86_VOYAGER) || PPC || ARM || BLACKFIN || MIPS \
  79                    || SUPERH || FRV
  80         depends on !SMP
  81         default y
  82
  83 config SUSPEND_SMP_POSSIBLE
  84         bool
  85         depends on (X86 && !X86_VOYAGER) \
  86                    || (PPC && (PPC_PSERIES || PPC_PMAC)) || ARM
  87         depends on SMP
  88         default y
  89
  90 config SUSPEND
  91         bool "Suspend to RAM and standby"
  92         depends on PM
  93         depends on SUSPEND_UP_POSSIBLE || SUSPEND_SMP_POSSIBLE
  94         default y
  95         ---help---
  96           Allow the system to enter sleep states in which main memory is
  97           powered and thus its contents are preserved, such as the
  98           suspend-to-RAM state (i.e. the ACPI S3 state).
  99
 100 config HIBERNATION_UP_POSSIBLE
 101         bool
 102         depends on X86 || PPC64_SWSUSP || PPC32
 103         depends on !SMP
 104         default y
 105
 106 config HIBERNATION_SMP_POSSIBLE
 107         bool
 108         depends on (X86 && !X86_VOYAGER) || PPC64_SWSUSP
 109         depends on SMP
 110         default y
 111
 112 config HIBERNATION
 113         bool "Hibernation (aka 'suspend to disk')"
 114         depends on PM && SWAP
 115         depends on HIBERNATION_UP_POSSIBLE || HIBERNATION_SMP_POSSIBLE
 116         ---help---
 117           Enable the suspend to disk (STD) functionality, which is usually
 118           called "hibernation" in user interfaces.  STD checkpoints the
 119           system and powers it off; and restores that checkpoint on reboot.
 120
 121           You can suspend your machine with 'echo disk > /sys/power/state'.
 122           Alternatively, you can use the additional userland tools available
 123           from <http://suspend.sf.net>.
 124
 125           In principle it does not require ACPI or APM, although for example
 126           ACPI will be used for the final steps when it is available.  One
 127           of the reasons to use software suspend is that the firmware hooks
 128           for suspend states like suspend-to-RAM (STR) often don't work very
 129           well with Linux.
 130
 131           It creates an image which is saved in your active swap. Upon the next
 132           boot, pass the 'resume=/dev/swappartition' argument to the kernel to
 133           have it detect the saved image, restore memory state from it, and
 134           continue to run as before. If you do not want the previous state to
 135           be reloaded, then use the 'noresume' kernel command line argument.
 136           Note, however, that fsck will be run on your filesystems and you will
 137           need to run mkswap against the swap partition used for the suspend.
 138
 139           It also works with swap files to a limited extent (for details see
 140           <file:Documentation/power/swsusp-and-swap-files.txt>).
 141
 142           Right now you may boot without resuming and resume later but in the
 143           meantime you cannot use the swap partition(s)/file(s) involved in
 144           suspending.  Also in this case you must not use the filesystems
 145           that were mounted before the suspend.  In particular, you MUST NOT
 146           MOUNT any journaled filesystems mounted before the suspend or they
 147           will get corrupted in a nasty way.
 148
 149           For more information take a look at <file:Documentation/power/swsusp.txt>.
 150
 151 config PM_STD_PARTITION
 152         string "Default resume partition"
 153         depends on HIBERNATION
 154         default ""
 155         ---help---
 156           The default resume partition is the partition that the suspend-
 157           to-disk implementation will look for a suspended disk image.
 158
 159           The partition specified here will be different for almost every user.
 160           It should be a valid swap partition (at least for now) that is turned
 161           on before suspending.
 162
 163           The partition specified can be overridden by specifying:
 164
 165                 resume=/dev/<other device>
 166
 167           which will set the resume partition to the device specified.
 168
 169           Note there is currently not a way to specify which device to save the
 170           suspended image to. It will simply pick the first available swap
 171           device.
 172
 173 config APM_EMULATION
 174         tristate "Advanced Power Management Emulation"
 175         depends on PM && SYS_SUPPORTS_APM_EMULATION
 176         help
 177           APM is a BIOS specification for saving power using several different
 178           techniques. This is mostly useful for battery powered laptops with
 179           APM compliant BIOSes. If you say Y here, the system time will be
 180           reset after a RESUME operation, the /proc/apm device will provide
 181           battery status information, and user-space programs will receive
 182           notification of APM "events" (e.g. battery status change).
 183
 184           In order to use APM, you will need supporting software. For location
 185           and more information, read <file:Documentation/pm.txt> and the
 186           Battery Powered Linux mini-HOWTO, available from
 187           <http://www.tldp.org/docs.html#howto>.
 188
 189           This driver does not spin down disk drives (see the hdparm(8)
 190           manpage ("man 8 hdparm") for that), and it doesn't turn off
 191           VESA-compliant "green" monitors.
 192
 193           Generally, if you don't have a battery in your machine, there isn't
 194           much point in using this driver and you should say N. If you get
 195           random kernel OOPSes or reboots that don't seem to be related to
 196           anything, try disabling/enabling this option (or disabling/enabling
 197           APM in your BIOS).