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_LIB=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 120 bool "Hibernation (aka 'suspend to disk')" 121 depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE 122 ---help--- 123 Enable the suspend to disk (STD) functionality, which is usually 124 called "hibernation" in user interfaces. STD checkpoints the 125 system and powers it off; and restores that checkpoint on reboot. 126 127 You can suspend your machine with 'echo disk > /sys/power/state' 128 after placing resume=/dev/swappartition on the kernel command line 129 in your bootloader's configuration file. 130 131 Alternatively, you can use the additional userland tools available 132 from <http://suspend.sf.net>. 133 134 In principle it does not require ACPI or APM, although for example 135 ACPI will be used for the final steps when it is available. One 136 of the reasons to use software suspend is that the firmware hooks 137 for suspend states like suspend-to-RAM (STR) often don't work very 138 well with Linux. 139 140 It creates an image which is saved in your active swap. Upon the next 141 boot, pass the 'resume=/dev/swappartition' argument to the kernel to 142 have it detect the saved image, restore memory state from it, and 143 continue to run as before. If you do not want the previous state to 144 be reloaded, then use the 'noresume' kernel command line argument. 145 Note, however, that fsck will be run on your filesystems and you will 146 need to run mkswap against the swap partition used for the suspend. 147 148 It also works with swap files to a limited extent (for details see 149 <file:Documentation/power/swsusp-and-swap-files.txt>). 150 151 Right now you may boot without resuming and resume later but in the 152 meantime you cannot use the swap partition(s)/file(s) involved in 153 suspending. Also in this case you must not use the filesystems 154 that were mounted before the suspend. In particular, you MUST NOT 155 MOUNT any journaled filesystems mounted before the suspend or they 156 will get corrupted in a nasty way. 157 158 For more information take a look at <file:Documentation/power/swsusp.txt>. 159 160config PM_STD_PARTITION 161 string "Default resume partition" 162 depends on HIBERNATION 163 default "" 164 ---help--- 165 The default resume partition is the partition that the suspend- 166 to-disk implementation will look for a suspended disk image. 167 168 The partition specified here will be different for almost every user. 169 It should be a valid swap partition (at least for now) that is turned 170 on before suspending. 171 172 The partition specified can be overridden by specifying: 173 174 resume=/dev/<other device> 175 176 which will set the resume partition to the device specified. 177 178 Note there is currently not a way to specify which device to save the 179 suspended image to. It will simply pick the first available swap 180 device. 181 182config APM_EMULATION 183 tristate "Advanced Power Management Emulation" 184 depends on PM && SYS_SUPPORTS_APM_EMULATION 185 help 186 APM is a BIOS specification for saving power using several different 187 techniques. This is mostly useful for battery powered laptops with 188 APM compliant BIOSes. If you say Y here, the system time will be 189 reset after a RESUME operation, the /proc/apm device will provide 190 battery status information, and user-space programs will receive 191 notification of APM "events" (e.g. battery status change). 192 193 In order to use APM, you will need supporting software. For location 194 and more information, read <file:Documentation/power/pm.txt> and the 195 Battery Powered Linux mini-HOWTO, available from 196 <http://www.tldp.org/docs.html#howto>. 197 198 This driver does not spin down disk drives (see the hdparm(8) 199 manpage ("man 8 hdparm") for that), and it doesn't turn off 200 VESA-compliant "green" monitors. 201 202 Generally, if you don't have a battery in your machine, there isn't 203 much point in using this driver and you should say N. If you get 204 random kernel OOPSes or reboots that don't seem to be related to 205 anything, try disabling/enabling this option (or disabling/enabling 206 APM in your BIOS). 207