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 DISABLE_CONSOLE_SUSPEND
  48         bool "Keep console(s) enabled during suspend/resume (DANGEROUS)"
  49         depends on PM_DEBUG
  50         default n
  51         ---help---
  52         This option turns off the console suspend mechanism that prevents
  53         debug messages from reaching the console during the suspend/resume
  54         operations.  This may be helpful when debugging device drivers'
  55         suspend/resume routines, but may itself lead to problems, for example
  56         if netconsole is used.
  57
  58 config PM_TRACE
  59         bool "Suspend/resume event tracing"
  60         depends on PM_DEBUG && X86 && EXPERIMENTAL
  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 machine,
  68         then reboot it, 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 HIBERNATION
  76         bool "Hibernation"
  77         depends on PM && SWAP && (((X86 || PPC64_SWSUSP) && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP))
  78         ---help---
  79           Enable the suspend to disk (STD) functionality, which is usually
  80           called "hibernation" in user interfaces.  STD checkpoints the
  81           system and powers it off; and restores that checkpoint on reboot.
  82
  83           You can suspend your machine with 'echo disk > /sys/power/state'.
  84           Alternatively, you can use the additional userland tools available
  85           from <http://suspend.sf.net>.
  86
  87           In principle it does not require ACPI or APM, although for example
  88           ACPI will be used for the final steps when it is available.  One
  89           of the reasons to use software suspend is that the firmware hooks
  90           for suspend states like suspend-to-RAM (STR) often don't work very
  91           well with Linux.
  92
  93           It creates an image which is saved in your active swap. Upon the next
  94           boot, pass the 'resume=/dev/swappartition' argument to the kernel to
  95           have it detect the saved image, restore memory state from it, and
  96           continue to run as before. If you do not want the previous state to
  97           be reloaded, then use the 'noresume' kernel command line argument.
  98           Note, however, that fsck will be run on your filesystems and you will
  99           need to run mkswap against the swap partition used for the suspend.
 100
 101           It also works with swap files to a limited extent (for details see
 102           <file:Documentation/power/swsusp-and-swap-files.txt>).
 103
 104           Right now you may boot without resuming and resume later but in the
 105           meantime you cannot use the swap partition(s)/file(s) involved in
 106           suspending.  Also in this case you must not use the filesystems
 107           that were mounted before the suspend.  In particular, you MUST NOT
 108           MOUNT any journaled filesystems mounted before the suspend or they
 109           will get corrupted in a nasty way.
 110
 111           For more information take a look at <file:Documentation/power/swsusp.txt>.
 112
 113 config PM_STD_PARTITION
 114         string "Default resume partition"
 115         depends on HIBERNATION
 116         default ""
 117         ---help---
 118           The default resume partition is the partition that the suspend-
 119           to-disk implementation will look for a suspended disk image.
 120
 121           The partition specified here will be different for almost every user.
 122           It should be a valid swap partition (at least for now) that is turned
 123           on before suspending.
 124
 125           The partition specified can be overridden by specifying:
 126
 127                 resume=/dev/<other device>
 128
 129           which will set the resume partition to the device specified.
 130
 131           Note there is currently not a way to specify which device to save the
 132           suspended image to. It will simply pick the first available swap
 133           device.
 134
 135 config SUSPEND_SMP
 136         bool
 137         depends on HOTPLUG_CPU && (X86 || PPC64) && PM
 138         default y
 139
 140 config APM_EMULATION
 141         tristate "Advanced Power Management Emulation"
 142         depends on PM && SYS_SUPPORTS_APM_EMULATION
 143         help
 144           APM is a BIOS specification for saving power using several different
 145           techniques. This is mostly useful for battery powered laptops with
 146           APM compliant BIOSes. If you say Y here, the system time will be
 147           reset after a RESUME operation, the /proc/apm device will provide
 148           battery status information, and user-space programs will receive
 149           notification of APM "events" (e.g. battery status change).
 150
 151           In order to use APM, you will need supporting software. For location
 152           and more information, read <file:Documentation/pm.txt> and the
 153           Battery Powered Linux mini-HOWTO, available from
 154           <http://www.tldp.org/docs.html#howto>.
 155
 156           This driver does not spin down disk drives (see the hdparm(8)
 157           manpage ("man 8 hdparm") for that), and it doesn't turn off
 158           VESA-compliant "green" monitors.
 159
 160           Generally, if you don't have a battery in your machine, there isn't
 161           much point in using this driver and you should say N. If you get
 162           random kernel OOPSes or reboots that don't seem to be related to
 163           anything, try disabling/enabling this option (or disabling/enabling
 164           APM in your BIOS).