xref: /openbmc/linux/kernel/power/Kconfig (revision 9d56dd3b083a3bec56e9da35ce07baca81030b03)
1config 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
22config PM_DEBUG
23	bool "Power Management Debug Support"
24	depends on PM
25	---help---
26	This option enables various debugging support in the Power Management
27	code. This is helpful when debugging and reporting PM bugs, like
28	suspend support.
29
30config PM_VERBOSE
31	bool "Verbose Power Management debugging"
32	depends on PM_DEBUG
33	default n
34	---help---
35	This option enables verbose messages from the Power Management code.
36
37config CAN_PM_TRACE
38	def_bool y
39	depends on PM_DEBUG && PM_SLEEP && EXPERIMENTAL
40
41config PM_TRACE
42	bool
43	help
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.
47
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.
51
52	  The way the information is presented is architecture-
53	  dependent, x86 will print the information during a
54	  late_initcall.
55
56config PM_TRACE_RTC
57	bool "Suspend/resume event tracing"
58	depends on CAN_PM_TRACE
59	depends on X86
60	select PM_TRACE
61	default n
62	---help---
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).
66
67	To use this debugging feature you should attempt to suspend the
68	machine, reboot it and then run
69
70		dmesg -s 1000000 | grep 'hash matches'
71
72	CAUTION: this option will cause your machine's real-time clock to be
73	set to an invalid time after a resume.
74
75config PM_SLEEP_SMP
76	bool
77	depends on SMP
78	depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE
79	depends on PM_SLEEP
80	select HOTPLUG_CPU
81	default y
82
83config PM_SLEEP
84	bool
85	depends on SUSPEND || HIBERNATION || XEN_SAVE_RESTORE
86	default y
87
88config SUSPEND
89	bool "Suspend to RAM and standby"
90	depends on PM && ARCH_SUSPEND_POSSIBLE
91	default y
92	---help---
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).
96
97config PM_TEST_SUSPEND
98	bool "Test suspend/resume and wakealarm during bootup"
99	depends on SUSPEND && PM_DEBUG && RTC_CLASS=y
100	---help---
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".
104
105	You probably want to have your system's RTC driver statically
106	linked, ensuring that it's available when this test runs.
107
108config SUSPEND_FREEZER
109	bool "Enable freezer for suspend to RAM/standby" \
110		if ARCH_WANTS_FREEZER_CONTROL || BROKEN
111	depends on SUSPEND
112	default y
113	help
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.
116
117	  Turning OFF this setting is NOT recommended! If in doubt, say Y.
118
119config HIBERNATION_NVS
120	bool
121
122config HIBERNATION
123	bool "Hibernation (aka 'suspend to disk')"
124	depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
125	select HIBERNATION_NVS if HAS_IOMEM
126	---help---
127	  Enable the suspend to disk (STD) functionality, which is usually
128	  called "hibernation" in user interfaces.  STD checkpoints the
129	  system and powers it off; and restores that checkpoint on reboot.
130
131	  You can suspend your machine with 'echo disk > /sys/power/state'
132	  after placing resume=/dev/swappartition on the kernel command line
133	  in your bootloader's configuration file.
134
135	  Alternatively, you can use the additional userland tools available
136	  from <http://suspend.sf.net>.
137
138	  In principle it does not require ACPI or APM, although for example
139	  ACPI will be used for the final steps when it is available.  One
140	  of the reasons to use software suspend is that the firmware hooks
141	  for suspend states like suspend-to-RAM (STR) often don't work very
142	  well with Linux.
143
144	  It creates an image which is saved in your active swap. Upon the next
145	  boot, pass the 'resume=/dev/swappartition' argument to the kernel to
146	  have it detect the saved image, restore memory state from it, and
147	  continue to run as before. If you do not want the previous state to
148	  be reloaded, then use the 'noresume' kernel command line argument.
149	  Note, however, that fsck will be run on your filesystems and you will
150	  need to run mkswap against the swap partition used for the suspend.
151
152	  It also works with swap files to a limited extent (for details see
153	  <file:Documentation/power/swsusp-and-swap-files.txt>).
154
155	  Right now you may boot without resuming and resume later but in the
156	  meantime you cannot use the swap partition(s)/file(s) involved in
157	  suspending.  Also in this case you must not use the filesystems
158	  that were mounted before the suspend.  In particular, you MUST NOT
159	  MOUNT any journaled filesystems mounted before the suspend or they
160	  will get corrupted in a nasty way.
161
162	  For more information take a look at <file:Documentation/power/swsusp.txt>.
163
164config PM_STD_PARTITION
165	string "Default resume partition"
166	depends on HIBERNATION
167	default ""
168	---help---
169	  The default resume partition is the partition that the suspend-
170	  to-disk implementation will look for a suspended disk image.
171
172	  The partition specified here will be different for almost every user.
173	  It should be a valid swap partition (at least for now) that is turned
174	  on before suspending.
175
176	  The partition specified can be overridden by specifying:
177
178		resume=/dev/<other device>
179
180	  which will set the resume partition to the device specified.
181
182	  Note there is currently not a way to specify which device to save the
183	  suspended image to. It will simply pick the first available swap
184	  device.
185
186config APM_EMULATION
187	tristate "Advanced Power Management Emulation"
188	depends on PM && SYS_SUPPORTS_APM_EMULATION
189	help
190	  APM is a BIOS specification for saving power using several different
191	  techniques. This is mostly useful for battery powered laptops with
192	  APM compliant BIOSes. If you say Y here, the system time will be
193	  reset after a RESUME operation, the /proc/apm device will provide
194	  battery status information, and user-space programs will receive
195	  notification of APM "events" (e.g. battery status change).
196
197	  In order to use APM, you will need supporting software. For location
198	  and more information, read <file:Documentation/power/pm.txt> and the
199	  Battery Powered Linux mini-HOWTO, available from
200	  <http://www.tldp.org/docs.html#howto>.
201
202	  This driver does not spin down disk drives (see the hdparm(8)
203	  manpage ("man 8 hdparm") for that), and it doesn't turn off
204	  VESA-compliant "green" monitors.
205
206	  Generally, if you don't have a battery in your machine, there isn't
207	  much point in using this driver and you should say N. If you get
208	  random kernel OOPSes or reboots that don't seem to be related to
209	  anything, try disabling/enabling this option (or disabling/enabling
210	  APM in your BIOS).
211
212config PM_RUNTIME
213	bool "Run-time PM core functionality"
214	depends on PM
215	---help---
216	  Enable functionality allowing I/O devices to be put into energy-saving
217	  (low power) states at run time (or autosuspended) after a specified
218	  period of inactivity and woken up in response to a hardware-generated
219	  wake-up event or a driver's request.
220
221	  Hardware support is generally required for this functionality to work
222	  and the bus type drivers of the buses the devices are on are
223	  responsible for the actual handling of the autosuspend requests and
224	  wake-up events.
225