xref: /openbmc/linux/kernel/power/Kconfig (revision 023e4163)
1config SUSPEND
2	bool "Suspend to RAM and standby"
3	depends on ARCH_SUSPEND_POSSIBLE
4	default y
5	---help---
6	  Allow the system to enter sleep states in which main memory is
7	  powered and thus its contents are preserved, such as the
8	  suspend-to-RAM state (e.g. the ACPI S3 state).
9
10config SUSPEND_FREEZER
11	bool "Enable freezer for suspend to RAM/standby" \
12		if ARCH_WANTS_FREEZER_CONTROL || BROKEN
13	depends on SUSPEND
14	default y
15	help
16	  This allows you to turn off the freezer for suspend. If this is
17	  done, no tasks are frozen for suspend to RAM/standby.
18
19	  Turning OFF this setting is NOT recommended! If in doubt, say Y.
20
21config SUSPEND_SKIP_SYNC
22	bool "Skip kernel's sys_sync() on suspend to RAM/standby"
23	depends on SUSPEND
24	depends on EXPERT
25	help
26	  Skip the kernel sys_sync() before freezing user processes.
27	  Some systems prefer not to pay this cost on every invocation
28	  of suspend, or they are content with invoking sync() from
29	  user-space before invoking suspend.  Say Y if that's your case.
30
31config HIBERNATE_CALLBACKS
32	bool
33
34config HIBERNATION
35	bool "Hibernation (aka 'suspend to disk')"
36	depends on SWAP && ARCH_HIBERNATION_POSSIBLE
37	select HIBERNATE_CALLBACKS
38	select LZO_COMPRESS
39	select LZO_DECOMPRESS
40	select CRC32
41	---help---
42	  Enable the suspend to disk (STD) functionality, which is usually
43	  called "hibernation" in user interfaces.  STD checkpoints the
44	  system and powers it off; and restores that checkpoint on reboot.
45
46	  You can suspend your machine with 'echo disk > /sys/power/state'
47	  after placing resume=/dev/swappartition on the kernel command line
48	  in your bootloader's configuration file.
49
50	  Alternatively, you can use the additional userland tools available
51	  from <http://suspend.sf.net>.
52
53	  In principle it does not require ACPI or APM, although for example
54	  ACPI will be used for the final steps when it is available.  One
55	  of the reasons to use software suspend is that the firmware hooks
56	  for suspend states like suspend-to-RAM (STR) often don't work very
57	  well with Linux.
58
59	  It creates an image which is saved in your active swap. Upon the next
60	  boot, pass the 'resume=/dev/swappartition' argument to the kernel to
61	  have it detect the saved image, restore memory state from it, and
62	  continue to run as before. If you do not want the previous state to
63	  be reloaded, then use the 'noresume' kernel command line argument.
64	  Note, however, that fsck will be run on your filesystems and you will
65	  need to run mkswap against the swap partition used for the suspend.
66
67	  It also works with swap files to a limited extent (for details see
68	  <file:Documentation/power/swsusp-and-swap-files.txt>).
69
70	  Right now you may boot without resuming and resume later but in the
71	  meantime you cannot use the swap partition(s)/file(s) involved in
72	  suspending.  Also in this case you must not use the filesystems
73	  that were mounted before the suspend.  In particular, you MUST NOT
74	  MOUNT any journaled filesystems mounted before the suspend or they
75	  will get corrupted in a nasty way.
76
77	  For more information take a look at <file:Documentation/power/swsusp.txt>.
78
79config ARCH_SAVE_PAGE_KEYS
80	bool
81
82config PM_STD_PARTITION
83	string "Default resume partition"
84	depends on HIBERNATION
85	default ""
86	---help---
87	  The default resume partition is the partition that the suspend-
88	  to-disk implementation will look for a suspended disk image.
89
90	  The partition specified here will be different for almost every user.
91	  It should be a valid swap partition (at least for now) that is turned
92	  on before suspending.
93
94	  The partition specified can be overridden by specifying:
95
96		resume=/dev/<other device>
97
98	  which will set the resume partition to the device specified.
99
100	  Note there is currently not a way to specify which device to save the
101	  suspended image to. It will simply pick the first available swap
102	  device.
103
104config PM_SLEEP
105	def_bool y
106	depends on SUSPEND || HIBERNATE_CALLBACKS
107	select PM
108	select SRCU
109
110config PM_SLEEP_SMP
111	def_bool y
112	depends on SMP
113	depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE
114	depends on PM_SLEEP
115	select HOTPLUG_CPU
116
117config PM_AUTOSLEEP
118	bool "Opportunistic sleep"
119	depends on PM_SLEEP
120	default n
121	---help---
122	Allow the kernel to trigger a system transition into a global sleep
123	state automatically whenever there are no active wakeup sources.
124
125config PM_WAKELOCKS
126	bool "User space wakeup sources interface"
127	depends on PM_SLEEP
128	default n
129	---help---
130	Allow user space to create, activate and deactivate wakeup source
131	objects with the help of a sysfs-based interface.
132
133config PM_WAKELOCKS_LIMIT
134	int "Maximum number of user space wakeup sources (0 = no limit)"
135	range 0 100000
136	default 100
137	depends on PM_WAKELOCKS
138
139config PM_WAKELOCKS_GC
140	bool "Garbage collector for user space wakeup sources"
141	depends on PM_WAKELOCKS
142	default y
143
144config PM
145	bool "Device power management core functionality"
146	---help---
147	  Enable functionality allowing I/O devices to be put into energy-saving
148	  (low power) states, for example after a specified period of inactivity
149	  (autosuspended), and woken up in response to a hardware-generated
150	  wake-up event or a driver's request.
151
152	  Hardware support is generally required for this functionality to work
153	  and the bus type drivers of the buses the devices are on are
154	  responsible for the actual handling of device suspend requests and
155	  wake-up events.
156
157config PM_DEBUG
158	bool "Power Management Debug Support"
159	depends on PM
160	---help---
161	This option enables various debugging support in the Power Management
162	code. This is helpful when debugging and reporting PM bugs, like
163	suspend support.
164
165config PM_ADVANCED_DEBUG
166	bool "Extra PM attributes in sysfs for low-level debugging/testing"
167	depends on PM_DEBUG
168	---help---
169	Add extra sysfs attributes allowing one to access some Power Management
170	fields of device objects from user space.  If you are not a kernel
171	developer interested in debugging/testing Power Management, say "no".
172
173config PM_TEST_SUSPEND
174	bool "Test suspend/resume and wakealarm during bootup"
175	depends on SUSPEND && PM_DEBUG && RTC_CLASS=y
176	---help---
177	This option will let you suspend your machine during bootup, and
178	make it wake up a few seconds later using an RTC wakeup alarm.
179	Enable this with a kernel parameter like "test_suspend=mem".
180
181	You probably want to have your system's RTC driver statically
182	linked, ensuring that it's available when this test runs.
183
184config PM_SLEEP_DEBUG
185	def_bool y
186	depends on PM_DEBUG && PM_SLEEP
187
188config DPM_WATCHDOG
189	bool "Device suspend/resume watchdog"
190	depends on PM_DEBUG && PSTORE && EXPERT
191	---help---
192	  Sets up a watchdog timer to capture drivers that are
193	  locked up attempting to suspend/resume a device.
194	  A detected lockup causes system panic with message
195	  captured in pstore device for inspection in subsequent
196	  boot session.
197
198config DPM_WATCHDOG_TIMEOUT
199	int "Watchdog timeout in seconds"
200	range 1 120
201	default 120
202	depends on DPM_WATCHDOG
203
204config PM_TRACE
205	bool
206	help
207	  This enables code to save the last PM event point across
208	  reboot. The architecture needs to support this, x86 for
209	  example does by saving things in the RTC, see below.
210
211	  The architecture specific code must provide the extern
212	  functions from <linux/resume-trace.h> as well as the
213	  <asm/resume-trace.h> header with a TRACE_RESUME() macro.
214
215	  The way the information is presented is architecture-
216	  dependent, x86 will print the information during a
217	  late_initcall.
218
219config PM_TRACE_RTC
220	bool "Suspend/resume event tracing"
221	depends on PM_SLEEP_DEBUG
222	depends on X86
223	select PM_TRACE
224	---help---
225	This enables some cheesy code to save the last PM event point in the
226	RTC across reboots, so that you can debug a machine that just hangs
227	during suspend (or more commonly, during resume).
228
229	To use this debugging feature you should attempt to suspend the
230	machine, reboot it and then run
231
232		dmesg -s 1000000 | grep 'hash matches'
233
234	CAUTION: this option will cause your machine's real-time clock to be
235	set to an invalid time after a resume.
236
237config APM_EMULATION
238	tristate "Advanced Power Management Emulation"
239	depends on SYS_SUPPORTS_APM_EMULATION
240	help
241	  APM is a BIOS specification for saving power using several different
242	  techniques. This is mostly useful for battery powered laptops with
243	  APM compliant BIOSes. If you say Y here, the system time will be
244	  reset after a RESUME operation, the /proc/apm device will provide
245	  battery status information, and user-space programs will receive
246	  notification of APM "events" (e.g. battery status change).
247
248	  In order to use APM, you will need supporting software. For location
249	  and more information, read <file:Documentation/power/apm-acpi.txt>
250	  and the Battery Powered Linux mini-HOWTO, available from
251	  <http://www.tldp.org/docs.html#howto>.
252
253	  This driver does not spin down disk drives (see the hdparm(8)
254	  manpage ("man 8 hdparm") for that), and it doesn't turn off
255	  VESA-compliant "green" monitors.
256
257	  Generally, if you don't have a battery in your machine, there isn't
258	  much point in using this driver and you should say N. If you get
259	  random kernel OOPSes or reboots that don't seem to be related to
260	  anything, try disabling/enabling this option (or disabling/enabling
261	  APM in your BIOS).
262
263config PM_CLK
264	def_bool y
265	depends on PM && HAVE_CLK
266
267config PM_GENERIC_DOMAINS
268	bool
269	depends on PM
270
271config WQ_POWER_EFFICIENT_DEFAULT
272	bool "Enable workqueue power-efficient mode by default"
273	depends on PM
274	default n
275	help
276	  Per-cpu workqueues are generally preferred because they show
277	  better performance thanks to cache locality; unfortunately,
278	  per-cpu workqueues tend to be more power hungry than unbound
279	  workqueues.
280
281	  Enabling workqueue.power_efficient kernel parameter makes the
282	  per-cpu workqueues which were observed to contribute
283	  significantly to power consumption unbound, leading to measurably
284	  lower power usage at the cost of small performance overhead.
285
286	  This config option determines whether workqueue.power_efficient
287	  is enabled by default.
288
289	  If in doubt, say N.
290
291config PM_GENERIC_DOMAINS_SLEEP
292	def_bool y
293	depends on PM_SLEEP && PM_GENERIC_DOMAINS
294
295config PM_GENERIC_DOMAINS_OF
296	def_bool y
297	depends on PM_GENERIC_DOMAINS && OF
298
299config CPU_PM
300	bool
301
302config ENERGY_MODEL
303	bool "Energy Model for CPUs"
304	depends on SMP
305	depends on CPU_FREQ
306	default n
307	help
308	  Several subsystems (thermal and/or the task scheduler for example)
309	  can leverage information about the energy consumed by CPUs to make
310	  smarter decisions. This config option enables the framework from
311	  which subsystems can access the energy models.
312
313	  The exact usage of the energy model is subsystem-dependent.
314
315	  If in doubt, say N.
316