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 CAN_PM_TRACE 48 def_bool y 49 depends on PM_DEBUG && PM_SLEEP && EXPERIMENTAL 50 51config PM_TRACE 52 bool 53 help 54 This enables code to save the last PM event point across 55 reboot. The architecture needs to support this, x86 for 56 example does by saving things in the RTC, see below. 57 58 The architecture specific code must provide the extern 59 functions from <linux/resume-trace.h> as well as the 60 <asm/resume-trace.h> header with a TRACE_RESUME() macro. 61 62 The way the information is presented is architecture- 63 dependent, x86 will print the information during a 64 late_initcall. 65 66config PM_TRACE_RTC 67 bool "Suspend/resume event tracing" 68 depends on CAN_PM_TRACE 69 depends on X86 70 select PM_TRACE 71 default n 72 ---help--- 73 This enables some cheesy code to save the last PM event point in the 74 RTC across reboots, so that you can debug a machine that just hangs 75 during suspend (or more commonly, during resume). 76 77 To use this debugging feature you should attempt to suspend the 78 machine, reboot it and then run 79 80 dmesg -s 1000000 | grep 'hash matches' 81 82 CAUTION: this option will cause your machine's real-time clock to be 83 set to an invalid time after a resume. 84 85config PM_SLEEP_SMP 86 bool 87 depends on SMP 88 depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE 89 depends on PM_SLEEP 90 select HOTPLUG_CPU 91 default y 92 93config PM_SLEEP 94 bool 95 depends on SUSPEND || HIBERNATION 96 default y 97 98config SUSPEND 99 bool "Suspend to RAM and standby" 100 depends on PM && ARCH_SUSPEND_POSSIBLE 101 default y 102 ---help--- 103 Allow the system to enter sleep states in which main memory is 104 powered and thus its contents are preserved, such as the 105 suspend-to-RAM state (e.g. the ACPI S3 state). 106 107config SUSPEND_FREEZER 108 bool "Enable freezer for suspend to RAM/standby" \ 109 if ARCH_WANTS_FREEZER_CONTROL || BROKEN 110 depends on SUSPEND 111 default y 112 help 113 This allows you to turn off the freezer for suspend. If this is 114 done, no tasks are frozen for suspend to RAM/standby. 115 116 Turning OFF this setting is NOT recommended! If in doubt, say Y. 117 118config HIBERNATION 119 bool "Hibernation (aka 'suspend to disk')" 120 depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE 121 ---help--- 122 Enable the suspend to disk (STD) functionality, which is usually 123 called "hibernation" in user interfaces. STD checkpoints the 124 system and powers it off; and restores that checkpoint on reboot. 125 126 You can suspend your machine with 'echo disk > /sys/power/state' 127 after placing resume=/dev/swappartition on the kernel command line 128 in your bootloader's configuration file. 129 130 Alternatively, you can use the additional userland tools available 131 from <http://suspend.sf.net>. 132 133 In principle it does not require ACPI or APM, although for example 134 ACPI will be used for the final steps when it is available. One 135 of the reasons to use software suspend is that the firmware hooks 136 for suspend states like suspend-to-RAM (STR) often don't work very 137 well with Linux. 138 139 It creates an image which is saved in your active swap. Upon the next 140 boot, pass the 'resume=/dev/swappartition' argument to the kernel to 141 have it detect the saved image, restore memory state from it, and 142 continue to run as before. If you do not want the previous state to 143 be reloaded, then use the 'noresume' kernel command line argument. 144 Note, however, that fsck will be run on your filesystems and you will 145 need to run mkswap against the swap partition used for the suspend. 146 147 It also works with swap files to a limited extent (for details see 148 <file:Documentation/power/swsusp-and-swap-files.txt>). 149 150 Right now you may boot without resuming and resume later but in the 151 meantime you cannot use the swap partition(s)/file(s) involved in 152 suspending. Also in this case you must not use the filesystems 153 that were mounted before the suspend. In particular, you MUST NOT 154 MOUNT any journaled filesystems mounted before the suspend or they 155 will get corrupted in a nasty way. 156 157 For more information take a look at <file:Documentation/power/swsusp.txt>. 158 159config PM_STD_PARTITION 160 string "Default resume partition" 161 depends on HIBERNATION 162 default "" 163 ---help--- 164 The default resume partition is the partition that the suspend- 165 to-disk implementation will look for a suspended disk image. 166 167 The partition specified here will be different for almost every user. 168 It should be a valid swap partition (at least for now) that is turned 169 on before suspending. 170 171 The partition specified can be overridden by specifying: 172 173 resume=/dev/<other device> 174 175 which will set the resume partition to the device specified. 176 177 Note there is currently not a way to specify which device to save the 178 suspended image to. It will simply pick the first available swap 179 device. 180 181config APM_EMULATION 182 tristate "Advanced Power Management Emulation" 183 depends on PM && SYS_SUPPORTS_APM_EMULATION 184 help 185 APM is a BIOS specification for saving power using several different 186 techniques. This is mostly useful for battery powered laptops with 187 APM compliant BIOSes. If you say Y here, the system time will be 188 reset after a RESUME operation, the /proc/apm device will provide 189 battery status information, and user-space programs will receive 190 notification of APM "events" (e.g. battery status change). 191 192 In order to use APM, you will need supporting software. For location 193 and more information, read <file:Documentation/power/pm.txt> and the 194 Battery Powered Linux mini-HOWTO, available from 195 <http://www.tldp.org/docs.html#howto>. 196 197 This driver does not spin down disk drives (see the hdparm(8) 198 manpage ("man 8 hdparm") for that), and it doesn't turn off 199 VESA-compliant "green" monitors. 200 201 Generally, if you don't have a battery in your machine, there isn't 202 much point in using this driver and you should say N. If you get 203 random kernel OOPSes or reboots that don't seem to be related to 204 anything, try disabling/enabling this option (or disabling/enabling 205 APM in your BIOS). 206