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 PM_SYSFS_DEPRECATED
  69         bool "Driver model /sys/devices/.../power/state files (DEPRECATED)"
  70         depends on PM && SYSFS
  71         default n
  72         help
  73           The driver model started out with a sysfs file intended to provide
  74           a userspace hook for device power management.  This feature has never
  75           worked very well, except for limited testing purposes, and so it will
  76           be removed.   It's not clear that a generic mechanism could really
  77           handle the wide variability of device power states; any replacements
  78           are likely to be bus or driver specific.
  79
  80 config SOFTWARE_SUSPEND
  81         bool "Software Suspend (Hibernation)"
  82         depends on PM && SWAP && (((X86 || PPC64_SWSUSP) && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP))
  83         ---help---
  84           Enable the suspend to disk (STD) functionality, which is usually
  85           called "hibernation" in user interfaces.  STD checkpoints the
  86           system and powers it off; and restores that checkpoint on reboot.
  87
  88           You can suspend your machine with 'echo disk > /sys/power/state'.
  89           Alternatively, you can use the additional userland tools available
  90           from <http://suspend.sf.net>.
  91
  92           In principle it does not require ACPI or APM, although for example
  93           ACPI will be used for the final steps when it is available.  One
  94           of the reasons to use software suspend is that the firmware hooks
  95           for suspend states like suspend-to-RAM (STR) often don't work very
  96           well with Linux.
  97
  98           It creates an image which is saved in your active swap. Upon the next
  99           boot, pass the 'resume=/dev/swappartition' argument to the kernel to
 100           have it detect the saved image, restore memory state from it, and
 101           continue to run as before. If you do not want the previous state to
 102           be reloaded, then use the 'noresume' kernel command line argument.
 103           Note, however, that fsck will be run on your filesystems and you will
 104           need to run mkswap against the swap partition used for the suspend.
 105
 106           It also works with swap files to a limited extent (for details see
 107           <file:Documentation/power/swsusp-and-swap-files.txt>).
 108
 109           Right now you may boot without resuming and resume later but in the
 110           meantime you cannot use the swap partition(s)/file(s) involved in
 111           suspending.  Also in this case you must not use the filesystems
 112           that were mounted before the suspend.  In particular, you MUST NOT
 113           MOUNT any journaled filesystems mounted before the suspend or they
 114           will get corrupted in a nasty way.
 115
 116           For more information take a look at <file:Documentation/power/swsusp.txt>.
 117
 118 config PM_STD_PARTITION
 119         string "Default resume partition"
 120         depends on SOFTWARE_SUSPEND
 121         default ""
 122         ---help---
 123           The default resume partition is the partition that the suspend-
 124           to-disk implementation will look for a suspended disk image.
 125
 126           The partition specified here will be different for almost every user.
 127           It should be a valid swap partition (at least for now) that is turned
 128           on before suspending.
 129
 130           The partition specified can be overridden by specifying:
 131
 132                 resume=/dev/<other device>
 133
 134           which will set the resume partition to the device specified.
 135
 136           Note there is currently not a way to specify which device to save the
 137           suspended image to. It will simply pick the first available swap
 138           device.
 139
 140 config SUSPEND_SMP
 141         bool
 142         depends on HOTPLUG_CPU && (X86 || PPC64) && PM
 143         default y
 144
 145 config APM_EMULATION
 146         tristate "Advanced Power Management Emulation"
 147         depends on PM && SYS_SUPPORTS_APM_EMULATION
 148         help
 149           APM is a BIOS specification for saving power using several different
 150           techniques. This is mostly useful for battery powered laptops with
 151           APM compliant BIOSes. If you say Y here, the system time will be
 152           reset after a RESUME operation, the /proc/apm device will provide
 153           battery status information, and user-space programs will receive
 154           notification of APM "events" (e.g. battery status change).
 155
 156           In order to use APM, you will need supporting software. For location
 157           and more information, read <file:Documentation/pm.txt> and the
 158           Battery Powered Linux mini-HOWTO, available from
 159           <http://www.tldp.org/docs.html#howto>.
 160
 161           This driver does not spin down disk drives (see the hdparm(8)
 162           manpage ("man 8 hdparm") for that), and it doesn't turn off
 163           VESA-compliant "green" monitors.
 164
 165           Generally, if you don't have a battery in your machine, there isn't
 166           much point in using this driver and you should say N. If you get
 167           random kernel OOPSes or reboots that don't seem to be related to
 168           anything, try disabling/enabling this option (or disabling/enabling
 169           APM in your BIOS).