xref: /openbmc/linux/kernel/power/Kconfig (revision c21b37f6)
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_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
32config PM_DEBUG
33	bool "Power Management Debug Support"
34	depends on PM
35	---help---
36	This option enables various debugging support in the Power Management
37	code. This is helpful when debugging and reporting PM bugs, like
38	suspend support.
39
40config PM_VERBOSE
41	bool "Verbose Power Management debugging"
42	depends on PM_DEBUG
43	default n
44	---help---
45	This option enables verbose messages from the Power Management code.
46
47config DISABLE_CONSOLE_SUSPEND
48	bool "Keep console(s) enabled during suspend/resume (DANGEROUS)"
49	depends on PM_DEBUG && PM_SLEEP
50	default n
51	---help---
52	This option turns off the console suspend mechanism that prevents
53	debug messages from reaching the console during the suspend/resume
54	operations.  This may be helpful when debugging device drivers'
55	suspend/resume routines, but may itself lead to problems, for example
56	if netconsole is used.
57
58config PM_TRACE
59	bool "Suspend/resume event tracing"
60	depends on PM_DEBUG && X86 && PM_SLEEP && EXPERIMENTAL
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 machine,
68	then reboot it, 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 SUSPEND_SMP_POSSIBLE
76	bool
77	depends on (X86 && !X86_VOYAGER) || (PPC64 && (PPC_PSERIES || PPC_PMAC))
78	depends on SMP
79	default y
80
81config SUSPEND_SMP
82	bool
83	depends on SUSPEND_SMP_POSSIBLE && PM_SLEEP
84	select HOTPLUG_CPU
85	default y
86
87config PM_SLEEP
88	bool
89	depends on SUSPEND || HIBERNATION
90	default y
91
92config SUSPEND
93	bool "Suspend to RAM and standby"
94	depends on PM
95	depends on !SMP || SUSPEND_SMP_POSSIBLE
96	default y
97	---help---
98	  Allow the system to enter sleep states in which main memory is
99	  powered and thus its contents are preserved, such as the
100	  suspend-to-RAM state (i.e. the ACPI S3 state).
101
102config HIBERNATION
103	bool "Hibernation (aka 'suspend to disk')"
104	depends on PM && SWAP
105	depends on ((X86 || PPC64_SWSUSP || FRV || PPC32) && !SMP) || SUSPEND_SMP_POSSIBLE
106	---help---
107	  Enable the suspend to disk (STD) functionality, which is usually
108	  called "hibernation" in user interfaces.  STD checkpoints the
109	  system and powers it off; and restores that checkpoint on reboot.
110
111	  You can suspend your machine with 'echo disk > /sys/power/state'.
112	  Alternatively, you can use the additional userland tools available
113	  from <http://suspend.sf.net>.
114
115	  In principle it does not require ACPI or APM, although for example
116	  ACPI will be used for the final steps when it is available.  One
117	  of the reasons to use software suspend is that the firmware hooks
118	  for suspend states like suspend-to-RAM (STR) often don't work very
119	  well with Linux.
120
121	  It creates an image which is saved in your active swap. Upon the next
122	  boot, pass the 'resume=/dev/swappartition' argument to the kernel to
123	  have it detect the saved image, restore memory state from it, and
124	  continue to run as before. If you do not want the previous state to
125	  be reloaded, then use the 'noresume' kernel command line argument.
126	  Note, however, that fsck will be run on your filesystems and you will
127	  need to run mkswap against the swap partition used for the suspend.
128
129	  It also works with swap files to a limited extent (for details see
130	  <file:Documentation/power/swsusp-and-swap-files.txt>).
131
132	  Right now you may boot without resuming and resume later but in the
133	  meantime you cannot use the swap partition(s)/file(s) involved in
134	  suspending.  Also in this case you must not use the filesystems
135	  that were mounted before the suspend.  In particular, you MUST NOT
136	  MOUNT any journaled filesystems mounted before the suspend or they
137	  will get corrupted in a nasty way.
138
139	  For more information take a look at <file:Documentation/power/swsusp.txt>.
140
141config PM_STD_PARTITION
142	string "Default resume partition"
143	depends on HIBERNATION
144	default ""
145	---help---
146	  The default resume partition is the partition that the suspend-
147	  to-disk implementation will look for a suspended disk image.
148
149	  The partition specified here will be different for almost every user.
150	  It should be a valid swap partition (at least for now) that is turned
151	  on before suspending.
152
153	  The partition specified can be overridden by specifying:
154
155		resume=/dev/<other device>
156
157	  which will set the resume partition to the device specified.
158
159	  Note there is currently not a way to specify which device to save the
160	  suspended image to. It will simply pick the first available swap
161	  device.
162
163config APM_EMULATION
164	tristate "Advanced Power Management Emulation"
165	depends on PM && SYS_SUPPORTS_APM_EMULATION
166	help
167	  APM is a BIOS specification for saving power using several different
168	  techniques. This is mostly useful for battery powered laptops with
169	  APM compliant BIOSes. If you say Y here, the system time will be
170	  reset after a RESUME operation, the /proc/apm device will provide
171	  battery status information, and user-space programs will receive
172	  notification of APM "events" (e.g. battery status change).
173
174	  In order to use APM, you will need supporting software. For location
175	  and more information, read <file:Documentation/pm.txt> and the
176	  Battery Powered Linux mini-HOWTO, available from
177	  <http://www.tldp.org/docs.html#howto>.
178
179	  This driver does not spin down disk drives (see the hdparm(8)
180	  manpage ("man 8 hdparm") for that), and it doesn't turn off
181	  VESA-compliant "green" monitors.
182
183	  Generally, if you don't have a battery in your machine, there isn't
184	  much point in using this driver and you should say N. If you get
185	  random kernel OOPSes or reboots that don't seem to be related to
186	  anything, try disabling/enabling this option (or disabling/enabling
187	  APM in your BIOS).
188