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 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 SUSPEND_FREEZER 98 bool "Enable freezer for suspend to RAM/standby" \ 99 if ARCH_WANTS_FREEZER_CONTROL || BROKEN 100 depends on SUSPEND 101 default y 102 help 103 This allows you to turn off the freezer for suspend. If this is 104 done, no tasks are frozen for suspend to RAM/standby. 105 106 Turning OFF this setting is NOT recommended! If in doubt, say Y. 107 108config HIBERNATION 109 bool "Hibernation (aka 'suspend to disk')" 110 depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE 111 ---help--- 112 Enable the suspend to disk (STD) functionality, which is usually 113 called "hibernation" in user interfaces. STD checkpoints the 114 system and powers it off; and restores that checkpoint on reboot. 115 116 You can suspend your machine with 'echo disk > /sys/power/state' 117 after placing resume=/dev/swappartition on the kernel command line 118 in your bootloader's configuration file. 119 120 Alternatively, you can use the additional userland tools available 121 from <http://suspend.sf.net>. 122 123 In principle it does not require ACPI or APM, although for example 124 ACPI will be used for the final steps when it is available. One 125 of the reasons to use software suspend is that the firmware hooks 126 for suspend states like suspend-to-RAM (STR) often don't work very 127 well with Linux. 128 129 It creates an image which is saved in your active swap. Upon the next 130 boot, pass the 'resume=/dev/swappartition' argument to the kernel to 131 have it detect the saved image, restore memory state from it, and 132 continue to run as before. If you do not want the previous state to 133 be reloaded, then use the 'noresume' kernel command line argument. 134 Note, however, that fsck will be run on your filesystems and you will 135 need to run mkswap against the swap partition used for the suspend. 136 137 It also works with swap files to a limited extent (for details see 138 <file:Documentation/power/swsusp-and-swap-files.txt>). 139 140 Right now you may boot without resuming and resume later but in the 141 meantime you cannot use the swap partition(s)/file(s) involved in 142 suspending. Also in this case you must not use the filesystems 143 that were mounted before the suspend. In particular, you MUST NOT 144 MOUNT any journaled filesystems mounted before the suspend or they 145 will get corrupted in a nasty way. 146 147 For more information take a look at <file:Documentation/power/swsusp.txt>. 148 149config PM_STD_PARTITION 150 string "Default resume partition" 151 depends on HIBERNATION 152 default "" 153 ---help--- 154 The default resume partition is the partition that the suspend- 155 to-disk implementation will look for a suspended disk image. 156 157 The partition specified here will be different for almost every user. 158 It should be a valid swap partition (at least for now) that is turned 159 on before suspending. 160 161 The partition specified can be overridden by specifying: 162 163 resume=/dev/<other device> 164 165 which will set the resume partition to the device specified. 166 167 Note there is currently not a way to specify which device to save the 168 suspended image to. It will simply pick the first available swap 169 device. 170 171config APM_EMULATION 172 tristate "Advanced Power Management Emulation" 173 depends on PM && SYS_SUPPORTS_APM_EMULATION 174 help 175 APM is a BIOS specification for saving power using several different 176 techniques. This is mostly useful for battery powered laptops with 177 APM compliant BIOSes. If you say Y here, the system time will be 178 reset after a RESUME operation, the /proc/apm device will provide 179 battery status information, and user-space programs will receive 180 notification of APM "events" (e.g. battery status change). 181 182 In order to use APM, you will need supporting software. For location 183 and more information, read <file:Documentation/power/pm.txt> and the 184 Battery Powered Linux mini-HOWTO, available from 185 <http://www.tldp.org/docs.html#howto>. 186 187 This driver does not spin down disk drives (see the hdparm(8) 188 manpage ("man 8 hdparm") for that), and it doesn't turn off 189 VESA-compliant "green" monitors. 190 191 Generally, if you don't have a battery in your machine, there isn't 192 much point in using this driver and you should say N. If you get 193 random kernel OOPSes or reboots that don't seem to be related to 194 anything, try disabling/enabling this option (or disabling/enabling 195 APM in your BIOS). 196