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 verbose debugging support in the Power Management
  37         code. This is helpful when debugging and reporting various PM bugs,
  38         like suspend support.
  39
  40 config DISABLE_CONSOLE_SUSPEND
  41         bool "Keep console(s) enabled during suspend/resume (DANGEROUS)"
  42         depends on PM && PM_DEBUG
  43         default n
  44         ---help---
  45         This option turns off the console suspend mechanism that prevents
  46         debug messages from reaching the console during the suspend/resume
  47         operations.  This may be helpful when debugging device drivers'
  48         suspend/resume routines, but may itself lead to problems, for example
  49         if netconsole is used.
  50
  51 config PM_TRACE
  52         bool "Suspend/resume event tracing"
  53         depends on PM && PM_DEBUG && X86_32 && EXPERIMENTAL
  54         default n
  55         ---help---
  56         This enables some cheesy code to save the last PM event point in the
  57         RTC across reboots, so that you can debug a machine that just hangs
  58         during suspend (or more commonly, during resume).
  59
  60         To use this debugging feature you should attempt to suspend the machine,
  61         then reboot it, then run
  62
  63                 dmesg -s 1000000 | grep 'hash matches'
  64
  65         CAUTION: this option will cause your machine's real-time clock to be
  66         set to an invalid time after a resume.
  67
  68 config SOFTWARE_SUSPEND
  69         bool "Software Suspend (Hibernation)"
  70         depends on PM && SWAP && (((X86 || PPC64_SWSUSP) && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP))
  71         ---help---
  72           Enable the suspend to disk (STD) functionality, which is usually
  73           called "hibernation" in user interfaces.  STD checkpoints the
  74           system and powers it off; and restores that checkpoint on reboot.
  75
  76           You can suspend your machine with 'echo disk > /sys/power/state'.
  77           Alternatively, you can use the additional userland tools available
  78           from <http://suspend.sf.net>.
  79
  80           In principle it does not require ACPI or APM, although for example
  81           ACPI will be used for the final steps when it is available.  One
  82           of the reasons to use software suspend is that the firmware hooks
  83           for suspend states like suspend-to-RAM (STR) often don't work very
  84           well with Linux.
  85
  86           It creates an image which is saved in your active swap. Upon the next
  87           boot, pass the 'resume=/dev/swappartition' argument to the kernel to
  88           have it detect the saved image, restore memory state from it, and
  89           continue to run as before. If you do not want the previous state to
  90           be reloaded, then use the 'noresume' kernel command line argument.
  91           Note, however, that fsck will be run on your filesystems and you will
  92           need to run mkswap against the swap partition used for the suspend.
  93
  94           It also works with swap files to a limited extent (for details see
  95           <file:Documentation/power/swsusp-and-swap-files.txt>).
  96
  97           Right now you may boot without resuming and resume later but in the
  98           meantime you cannot use the swap partition(s)/file(s) involved in
  99           suspending.  Also in this case you must not use the filesystems
 100           that were mounted before the suspend.  In particular, you MUST NOT
 101           MOUNT any journaled filesystems mounted before the suspend or they
 102           will get corrupted in a nasty way.
 103
 104           For more information take a look at <file:Documentation/power/swsusp.txt>.
 105
 106 config PM_STD_PARTITION
 107         string "Default resume partition"
 108         depends on SOFTWARE_SUSPEND
 109         default ""
 110         ---help---
 111           The default resume partition is the partition that the suspend-
 112           to-disk implementation will look for a suspended disk image.
 113
 114           The partition specified here will be different for almost every user.
 115           It should be a valid swap partition (at least for now) that is turned
 116           on before suspending.
 117
 118           The partition specified can be overridden by specifying:
 119
 120                 resume=/dev/<other device>
 121
 122           which will set the resume partition to the device specified.
 123
 124           Note there is currently not a way to specify which device to save the
 125           suspended image to. It will simply pick the first available swap
 126           device.
 127
 128 config SUSPEND_SMP
 129         bool
 130         depends on HOTPLUG_CPU && (X86 || PPC64) && PM
 131         default y
 132
 133 config APM_EMULATION
 134         tristate "Advanced Power Management Emulation"
 135         depends on PM && SYS_SUPPORTS_APM_EMULATION
 136         help
 137           APM is a BIOS specification for saving power using several different
 138           techniques. This is mostly useful for battery powered laptops with
 139           APM compliant BIOSes. If you say Y here, the system time will be
 140           reset after a RESUME operation, the /proc/apm device will provide
 141           battery status information, and user-space programs will receive
 142           notification of APM "events" (e.g. battery status change).
 143
 144           In order to use APM, you will need supporting software. For location
 145           and more information, read <file:Documentation/pm.txt> and the
 146           Battery Powered Linux mini-HOWTO, available from
 147           <http://www.tldp.org/docs.html#howto>.
 148
 149           This driver does not spin down disk drives (see the hdparm(8)
 150           manpage ("man 8 hdparm") for that), and it doesn't turn off
 151           VESA-compliant "green" monitors.
 152
 153           Generally, if you don't have a battery in your machine, there isn't
 154           much point in using this driver and you should say N. If you get
 155           random kernel OOPSes or reboots that don't seem to be related to
 156           anything, try disabling/enabling this option (or disabling/enabling
 157           APM in your BIOS).