1 # SPDX-License-Identifier: GPL-2.0-only
3 bool "Suspend to RAM and standby"
4 depends on ARCH_SUSPEND_POSSIBLE
7 Allow the system to enter sleep states in which main memory is
8 powered and thus its contents are preserved, such as the
9 suspend-to-RAM state (e.g. the ACPI S3 state).
11 config SUSPEND_FREEZER
12 bool "Enable freezer for suspend to RAM/standby" \
13 if ARCH_WANTS_FREEZER_CONTROL || BROKEN
17 This allows you to turn off the freezer for suspend. If this is
18 done, no tasks are frozen for suspend to RAM/standby.
20 Turning OFF this setting is NOT recommended! If in doubt, say Y.
22 config SUSPEND_SKIP_SYNC
23 bool "Skip kernel's sys_sync() on suspend to RAM/standby"
27 Skip the kernel sys_sync() before freezing user processes.
28 Some systems prefer not to pay this cost on every invocation
29 of suspend, or they are content with invoking sync() from
30 user-space before invoking suspend. There's a run-time switch
31 at '/sys/power/sync_on_suspend' to configure this behaviour.
32 This setting changes the default for the run-tim switch. Say Y
33 to change the default to disable the kernel sys_sync().
35 config HIBERNATE_CALLBACKS
39 bool "Hibernation (aka 'suspend to disk')"
40 depends on SWAP && ARCH_HIBERNATION_POSSIBLE
41 select HIBERNATE_CALLBACKS
46 Enable the suspend to disk (STD) functionality, which is usually
47 called "hibernation" in user interfaces. STD checkpoints the
48 system and powers it off; and restores that checkpoint on reboot.
50 You can suspend your machine with 'echo disk > /sys/power/state'
51 after placing resume=/dev/swappartition on the kernel command line
52 in your bootloader's configuration file.
54 Alternatively, you can use the additional userland tools available
55 from <http://suspend.sf.net>.
57 In principle it does not require ACPI or APM, although for example
58 ACPI will be used for the final steps when it is available. One
59 of the reasons to use software suspend is that the firmware hooks
60 for suspend states like suspend-to-RAM (STR) often don't work very
63 It creates an image which is saved in your active swap. Upon the next
64 boot, pass the 'resume=/dev/swappartition' argument to the kernel to
65 have it detect the saved image, restore memory state from it, and
66 continue to run as before. If you do not want the previous state to
67 be reloaded, then use the 'noresume' kernel command line argument.
68 Note, however, that fsck will be run on your filesystems and you will
69 need to run mkswap against the swap partition used for the suspend.
71 It also works with swap files to a limited extent (for details see
72 <file:Documentation/power/swsusp-and-swap-files.rst>).
74 Right now you may boot without resuming and resume later but in the
75 meantime you cannot use the swap partition(s)/file(s) involved in
76 suspending. Also in this case you must not use the filesystems
77 that were mounted before the suspend. In particular, you MUST NOT
78 MOUNT any journaled filesystems mounted before the suspend or they
79 will get corrupted in a nasty way.
81 For more information take a look at <file:Documentation/power/swsusp.rst>.
83 config HIBERNATION_SNAPSHOT_DEV
84 bool "Userspace snapshot device"
85 depends on HIBERNATION
88 Device used by the uswsusp tools.
90 Say N if no snapshotting from userspace is needed, this also
91 reduces the attack surface of the kernel.
95 config PM_STD_PARTITION
96 string "Default resume partition"
97 depends on HIBERNATION
100 The default resume partition is the partition that the suspend-
101 to-disk implementation will look for a suspended disk image.
103 The partition specified here will be different for almost every user.
104 It should be a valid swap partition (at least for now) that is turned
105 on before suspending.
107 The partition specified can be overridden by specifying:
109 resume=/dev/<other device>
111 which will set the resume partition to the device specified.
113 Note there is currently not a way to specify which device to save the
114 suspended image to. It will simply pick the first available swap
119 depends on SUSPEND || HIBERNATE_CALLBACKS
126 depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE
130 config PM_SLEEP_SMP_NONZERO_CPU
132 depends on PM_SLEEP_SMP
133 depends on ARCH_SUSPEND_NONZERO_CPU
135 If an arch can suspend (for suspend, hibernate, kexec, etc) on a
136 non-zero numbered CPU, it may define ARCH_SUSPEND_NONZERO_CPU. This
137 will allow nohz_full mask to include CPU0.
140 bool "Opportunistic sleep"
143 Allow the kernel to trigger a system transition into a global sleep
144 state automatically whenever there are no active wakeup sources.
146 config PM_USERSPACE_AUTOSLEEP
147 bool "Userspace opportunistic sleep"
150 Notify kernel of aggressive userspace autosleep power management policy.
152 This option changes the behavior of various sleep-sensitive code to deal
153 with frequent userspace-initiated transitions into a global sleep state.
155 Saying Y here, disables code paths that most users really should keep
156 enabled. In particular, only enable this if it is very common to be
157 asleep/awake for very short periods of time (<= 2 seconds).
159 Only platforms, such as Android, that implement opportunistic sleep from
160 a userspace power manager service should enable this option; and not
161 other machines. Therefore, you should say N here, unless you are
162 extremely certain that this is what you want. The option otherwise has
163 bad, undesirable effects, and should not be enabled just for fun.
167 bool "User space wakeup sources interface"
170 Allow user space to create, activate and deactivate wakeup source
171 objects with the help of a sysfs-based interface.
173 config PM_WAKELOCKS_LIMIT
174 int "Maximum number of user space wakeup sources (0 = no limit)"
177 depends on PM_WAKELOCKS
179 config PM_WAKELOCKS_GC
180 bool "Garbage collector for user space wakeup sources"
181 depends on PM_WAKELOCKS
185 bool "Device power management core functionality"
187 Enable functionality allowing I/O devices to be put into energy-saving
188 (low power) states, for example after a specified period of inactivity
189 (autosuspended), and woken up in response to a hardware-generated
190 wake-up event or a driver's request.
192 Hardware support is generally required for this functionality to work
193 and the bus type drivers of the buses the devices are on are
194 responsible for the actual handling of device suspend requests and
198 bool "Power Management Debug Support"
201 This option enables various debugging support in the Power Management
202 code. This is helpful when debugging and reporting PM bugs, like
205 config PM_ADVANCED_DEBUG
206 bool "Extra PM attributes in sysfs for low-level debugging/testing"
209 Add extra sysfs attributes allowing one to access some Power Management
210 fields of device objects from user space. If you are not a kernel
211 developer interested in debugging/testing Power Management, say "no".
213 config PM_TEST_SUSPEND
214 bool "Test suspend/resume and wakealarm during bootup"
215 depends on SUSPEND && PM_DEBUG && RTC_CLASS=y
217 This option will let you suspend your machine during bootup, and
218 make it wake up a few seconds later using an RTC wakeup alarm.
219 Enable this with a kernel parameter like "test_suspend=mem".
221 You probably want to have your system's RTC driver statically
222 linked, ensuring that it's available when this test runs.
224 config PM_SLEEP_DEBUG
226 depends on PM_DEBUG && PM_SLEEP
229 bool "Device suspend/resume watchdog"
230 depends on PM_DEBUG && PSTORE && EXPERT
232 Sets up a watchdog timer to capture drivers that are
233 locked up attempting to suspend/resume a device.
234 A detected lockup causes system panic with message
235 captured in pstore device for inspection in subsequent
238 config DPM_WATCHDOG_TIMEOUT
239 int "Watchdog timeout in seconds"
242 depends on DPM_WATCHDOG
247 This enables code to save the last PM event point across
248 reboot. The architecture needs to support this, x86 for
249 example does by saving things in the RTC, see below.
251 The architecture specific code must provide the extern
252 functions from <linux/resume-trace.h> as well as the
253 <asm/resume-trace.h> header with a TRACE_RESUME() macro.
255 The way the information is presented is architecture-
256 dependent, x86 will print the information during a
260 bool "Suspend/resume event tracing"
261 depends on PM_SLEEP_DEBUG
265 This enables some cheesy code to save the last PM event point in the
266 RTC across reboots, so that you can debug a machine that just hangs
267 during suspend (or more commonly, during resume).
269 To use this debugging feature you should attempt to suspend the
270 machine, reboot it and then run
272 dmesg -s 1000000 | grep 'hash matches'
274 CAUTION: this option will cause your machine's real-time clock to be
275 set to an invalid time after a resume.
278 tristate "Advanced Power Management Emulation"
279 depends on SYS_SUPPORTS_APM_EMULATION
281 APM is a BIOS specification for saving power using several different
282 techniques. This is mostly useful for battery powered laptops with
283 APM compliant BIOSes. If you say Y here, the system time will be
284 reset after a RESUME operation, the /proc/apm device will provide
285 battery status information, and user-space programs will receive
286 notification of APM "events" (e.g. battery status change).
288 In order to use APM, you will need supporting software. For location
289 and more information, read <file:Documentation/power/apm-acpi.rst>
290 and the Battery Powered Linux mini-HOWTO, available from
291 <http://www.tldp.org/docs.html#howto>.
293 This driver does not spin down disk drives (see the hdparm(8)
294 manpage ("man 8 hdparm") for that), and it doesn't turn off
295 VESA-compliant "green" monitors.
297 Generally, if you don't have a battery in your machine, there isn't
298 much point in using this driver and you should say N. If you get
299 random kernel OOPSes or reboots that don't seem to be related to
300 anything, try disabling/enabling this option (or disabling/enabling
305 depends on PM && HAVE_CLK
307 config PM_GENERIC_DOMAINS
311 config WQ_POWER_EFFICIENT_DEFAULT
312 bool "Enable workqueue power-efficient mode by default"
315 Per-cpu workqueues are generally preferred because they show
316 better performance thanks to cache locality; unfortunately,
317 per-cpu workqueues tend to be more power hungry than unbound
320 Enabling workqueue.power_efficient kernel parameter makes the
321 per-cpu workqueues which were observed to contribute
322 significantly to power consumption unbound, leading to measurably
323 lower power usage at the cost of small performance overhead.
325 This config option determines whether workqueue.power_efficient
326 is enabled by default.
330 config PM_GENERIC_DOMAINS_SLEEP
332 depends on PM_SLEEP && PM_GENERIC_DOMAINS
334 config PM_GENERIC_DOMAINS_OF
336 depends on PM_GENERIC_DOMAINS && OF
342 bool "Energy Model for devices with DVFS (CPUs, GPUs, etc)"
346 Several subsystems (thermal and/or the task scheduler for example)
347 can leverage information about the energy consumed by devices to
348 make smarter decisions. This config option enables the framework
349 from which subsystems can access the energy models.
351 The exact usage of the energy model is subsystem-dependent.