2 bool "Power Management support"
3 depends on !IA64_HP_SIM
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.
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>.
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.
23 bool "Power Management Debug Support"
26 This option enables various debugging support in the Power Management
27 code. This is helpful when debugging and reporting PM bugs, like
31 bool "Verbose Power Management debugging"
35 This option enables verbose messages from the Power Management code.
39 depends on PM_DEBUG && PM_SLEEP && EXPERIMENTAL
44 This enables code to save the last PM event point across
45 reboot. The architecture needs to support this, x86 for
46 example does by saving things in the RTC, see below.
48 The architecture specific code must provide the extern
49 functions from <linux/resume-trace.h> as well as the
50 <asm/resume-trace.h> header with a TRACE_RESUME() macro.
52 The way the information is presented is architecture-
53 dependent, x86 will print the information during a
57 bool "Suspend/resume event tracing"
58 depends on CAN_PM_TRACE
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).
67 To use this debugging feature you should attempt to suspend the
68 machine, reboot it and then run
70 dmesg -s 1000000 | grep 'hash matches'
72 CAUTION: this option will cause your machine's real-time clock to be
73 set to an invalid time after a resume.
78 depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE
85 depends on SUSPEND || HIBERNATION || XEN_SAVE_RESTORE
89 bool "Suspend to RAM and standby"
90 depends on PM && ARCH_SUSPEND_POSSIBLE
93 Allow the system to enter sleep states in which main memory is
94 powered and thus its contents are preserved, such as the
95 suspend-to-RAM state (e.g. the ACPI S3 state).
97 config PM_TEST_SUSPEND
98 bool "Test suspend/resume and wakealarm during bootup"
99 depends on SUSPEND && PM_DEBUG && RTC_CLASS=y
101 This option will let you suspend your machine during bootup, and
102 make it wake up a few seconds later using an RTC wakeup alarm.
103 Enable this with a kernel parameter like "test_suspend=mem".
105 You probably want to have your system's RTC driver statically
106 linked, ensuring that it's available when this test runs.
108 config SUSPEND_FREEZER
109 bool "Enable freezer for suspend to RAM/standby" \
110 if ARCH_WANTS_FREEZER_CONTROL || BROKEN
114 This allows you to turn off the freezer for suspend. If this is
115 done, no tasks are frozen for suspend to RAM/standby.
117 Turning OFF this setting is NOT recommended! If in doubt, say Y.
119 config HIBERNATION_NVS
125 config HAS_EARLYSUSPEND
130 depends on PM && RTC_CLASS
134 Enable wakelocks. When user space request a sleep state the
135 sleep request will be delayed until no wake locks are held.
138 bool "Wake lock stats"
142 Report wake lock stats in /proc/wakelocks
145 bool "Userspace wake locks"
149 User-space wake lock api. Write "lockname" or "lockname timeout"
150 to /sys/power/wake_lock lock and if needed create a wake lock.
151 Write "lockname" to /sys/power/wake_unlock to unlock a user wake
158 select HAS_EARLYSUSPEND
160 Call early suspend handlers when the user requested sleep state
164 prompt "User-space screen access"
165 default CONSOLE_EARLYSUSPEND
166 depends on HAS_EARLYSUSPEND
168 config NO_USER_SPACE_SCREEN_ACCESS_CONTROL
171 config CONSOLE_EARLYSUSPEND
172 bool "Console switch on early-suspend"
173 depends on HAS_EARLYSUSPEND && VT
175 Register early suspend handler to perform a console switch to
176 when user-space should stop drawing to the screen and a switch
177 back when it should resume.
181 bool "Hibernation (aka 'suspend to disk')"
182 depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
183 select HIBERNATION_NVS if HAS_IOMEM
185 Enable the suspend to disk (STD) functionality, which is usually
186 called "hibernation" in user interfaces. STD checkpoints the
187 system and powers it off; and restores that checkpoint on reboot.
189 You can suspend your machine with 'echo disk > /sys/power/state'
190 after placing resume=/dev/swappartition on the kernel command line
191 in your bootloader's configuration file.
193 Alternatively, you can use the additional userland tools available
194 from <http://suspend.sf.net>.
196 In principle it does not require ACPI or APM, although for example
197 ACPI will be used for the final steps when it is available. One
198 of the reasons to use software suspend is that the firmware hooks
199 for suspend states like suspend-to-RAM (STR) often don't work very
202 It creates an image which is saved in your active swap. Upon the next
203 boot, pass the 'resume=/dev/swappartition' argument to the kernel to
204 have it detect the saved image, restore memory state from it, and
205 continue to run as before. If you do not want the previous state to
206 be reloaded, then use the 'noresume' kernel command line argument.
207 Note, however, that fsck will be run on your filesystems and you will
208 need to run mkswap against the swap partition used for the suspend.
210 It also works with swap files to a limited extent (for details see
211 <file:Documentation/power/swsusp-and-swap-files.txt>).
213 Right now you may boot without resuming and resume later but in the
214 meantime you cannot use the swap partition(s)/file(s) involved in
215 suspending. Also in this case you must not use the filesystems
216 that were mounted before the suspend. In particular, you MUST NOT
217 MOUNT any journaled filesystems mounted before the suspend or they
218 will get corrupted in a nasty way.
220 For more information take a look at <file:Documentation/power/swsusp.txt>.
222 config PM_STD_PARTITION
223 string "Default resume partition"
224 depends on HIBERNATION
227 The default resume partition is the partition that the suspend-
228 to-disk implementation will look for a suspended disk image.
230 The partition specified here will be different for almost every user.
231 It should be a valid swap partition (at least for now) that is turned
232 on before suspending.
234 The partition specified can be overridden by specifying:
236 resume=/dev/<other device>
238 which will set the resume partition to the device specified.
240 Note there is currently not a way to specify which device to save the
241 suspended image to. It will simply pick the first available swap
245 tristate "Advanced Power Management Emulation"
246 depends on PM && SYS_SUPPORTS_APM_EMULATION
248 APM is a BIOS specification for saving power using several different
249 techniques. This is mostly useful for battery powered laptops with
250 APM compliant BIOSes. If you say Y here, the system time will be
251 reset after a RESUME operation, the /proc/apm device will provide
252 battery status information, and user-space programs will receive
253 notification of APM "events" (e.g. battery status change).
255 In order to use APM, you will need supporting software. For location
256 and more information, read <file:Documentation/power/pm.txt> and the
257 Battery Powered Linux mini-HOWTO, available from
258 <http://www.tldp.org/docs.html#howto>.
260 This driver does not spin down disk drives (see the hdparm(8)
261 manpage ("man 8 hdparm") for that), and it doesn't turn off
262 VESA-compliant "green" monitors.
264 Generally, if you don't have a battery in your machine, there isn't
265 much point in using this driver and you should say N. If you get
266 random kernel OOPSes or reboots that don't seem to be related to
267 anything, try disabling/enabling this option (or disabling/enabling
271 bool "Run-time PM core functionality"
274 Enable functionality allowing I/O devices to be put into energy-saving
275 (low power) states at run time (or autosuspended) after a specified
276 period of inactivity and woken up in response to a hardware-generated
277 wake-up event or a driver's request.
279 Hardware support is generally required for this functionality to work
280 and the bus type drivers of the buses the devices are on are
281 responsible for the actual handling of the autosuspend requests and