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
92 bool "Suspend to RAM and standby"
93 depends on PM && ARCH_SUSPEND_POSSIBLE
96 Allow the system to enter sleep states in which main memory is
97 powered and thus its contents are preserved, such as the
98 suspend-to-RAM state (e.g. the ACPI S3 state).
100 config PM_TEST_SUSPEND
101 bool "Test suspend/resume and wakealarm during bootup"
102 depends on SUSPEND && PM_DEBUG && RTC_LIB=y
104 This option will let you suspend your machine during bootup, and
105 make it wake up a few seconds later using an RTC wakeup alarm.
106 Enable this with a kernel parameter like "test_suspend=mem".
108 You probably want to have your system's RTC driver statically
109 linked, ensuring that it's available when this test runs.
111 config SUSPEND_FREEZER
112 bool "Enable freezer for suspend to RAM/standby" \
113 if ARCH_WANTS_FREEZER_CONTROL || BROKEN
117 This allows you to turn off the freezer for suspend. If this is
118 done, no tasks are frozen for suspend to RAM/standby.
120 Turning OFF this setting is NOT recommended! If in doubt, say Y.
123 bool "Hibernation (aka 'suspend to disk')"
124 depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE
126 Enable the suspend to disk (STD) functionality, which is usually
127 called "hibernation" in user interfaces. STD checkpoints the
128 system and powers it off; and restores that checkpoint on reboot.
130 You can suspend your machine with 'echo disk > /sys/power/state'
131 after placing resume=/dev/swappartition on the kernel command line
132 in your bootloader's configuration file.
134 Alternatively, you can use the additional userland tools available
135 from <http://suspend.sf.net>.
137 In principle it does not require ACPI or APM, although for example
138 ACPI will be used for the final steps when it is available. One
139 of the reasons to use software suspend is that the firmware hooks
140 for suspend states like suspend-to-RAM (STR) often don't work very
143 It creates an image which is saved in your active swap. Upon the next
144 boot, pass the 'resume=/dev/swappartition' argument to the kernel to
145 have it detect the saved image, restore memory state from it, and
146 continue to run as before. If you do not want the previous state to
147 be reloaded, then use the 'noresume' kernel command line argument.
148 Note, however, that fsck will be run on your filesystems and you will
149 need to run mkswap against the swap partition used for the suspend.
151 It also works with swap files to a limited extent (for details see
152 <file:Documentation/power/swsusp-and-swap-files.txt>).
154 Right now you may boot without resuming and resume later but in the
155 meantime you cannot use the swap partition(s)/file(s) involved in
156 suspending. Also in this case you must not use the filesystems
157 that were mounted before the suspend. In particular, you MUST NOT
158 MOUNT any journaled filesystems mounted before the suspend or they
159 will get corrupted in a nasty way.
161 For more information take a look at <file:Documentation/power/swsusp.txt>.
163 config PM_STD_PARTITION
164 string "Default resume partition"
165 depends on HIBERNATION
168 The default resume partition is the partition that the suspend-
169 to-disk implementation will look for a suspended disk image.
171 The partition specified here will be different for almost every user.
172 It should be a valid swap partition (at least for now) that is turned
173 on before suspending.
175 The partition specified can be overridden by specifying:
177 resume=/dev/<other device>
179 which will set the resume partition to the device specified.
181 Note there is currently not a way to specify which device to save the
182 suspended image to. It will simply pick the first available swap
186 tristate "Advanced Power Management Emulation"
187 depends on PM && SYS_SUPPORTS_APM_EMULATION
189 APM is a BIOS specification for saving power using several different
190 techniques. This is mostly useful for battery powered laptops with
191 APM compliant BIOSes. If you say Y here, the system time will be
192 reset after a RESUME operation, the /proc/apm device will provide
193 battery status information, and user-space programs will receive
194 notification of APM "events" (e.g. battery status change).
196 In order to use APM, you will need supporting software. For location
197 and more information, read <file:Documentation/power/pm.txt> and the
198 Battery Powered Linux mini-HOWTO, available from
199 <http://www.tldp.org/docs.html#howto>.
201 This driver does not spin down disk drives (see the hdparm(8)
202 manpage ("man 8 hdparm") for that), and it doesn't turn off
203 VESA-compliant "green" monitors.
205 Generally, if you don't have a battery in your machine, there isn't
206 much point in using this driver and you should say N. If you get
207 random kernel OOPSes or reboots that don't seem to be related to
208 anything, try disabling/enabling this option (or disabling/enabling