1What: /sys/power/ 2Date: August 2006 3Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 4Description: 5 The /sys/power directory will contain files that will 6 provide a unified interface to the power management 7 subsystem. 8 9What: /sys/power/state 10Date: November 2016 11Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 12Description: 13 The /sys/power/state file controls system sleep states. 14 Reading from this file returns the available sleep state 15 labels, which may be "mem" (suspend), "standby" (power-on 16 suspend), "freeze" (suspend-to-idle) and "disk" (hibernation). 17 18 Writing one of the above strings to this file causes the system 19 to transition into the corresponding state, if available. 20 21 See Documentation/admin-guide/pm/sleep-states.rst for more 22 information. 23 24What: /sys/power/mem_sleep 25Date: November 2016 26Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 27Description: 28 The /sys/power/mem_sleep file controls the operating mode of 29 system suspend. Reading from it returns the available modes 30 as "s2idle" (always present), "shallow" and "deep" (present if 31 supported). The mode that will be used on subsequent attempts 32 to suspend the system (by writing "mem" to the /sys/power/state 33 file described above) is enclosed in square brackets. 34 35 Writing one of the above strings to this file causes the mode 36 represented by it to be used on subsequent attempts to suspend 37 the system. 38 39 See Documentation/admin-guide/pm/sleep-states.rst for more 40 information. 41 42What: /sys/power/disk 43Date: September 2006 44Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 45Description: 46 The /sys/power/disk file controls the operating mode of the 47 suspend-to-disk mechanism. Reading from this file returns 48 the name of the method by which the system will be put to 49 sleep on the next suspend. There are four methods supported: 50 51 'firmware' - means that the memory image will be saved to disk 52 by some firmware, in which case we also assume that the 53 firmware will handle the system suspend. 54 55 'platform' - the memory image will be saved by the kernel and 56 the system will be put to sleep by the platform driver (e.g. 57 ACPI or other PM registers). 58 59 'shutdown' - the memory image will be saved by the kernel and 60 the system will be powered off. 61 62 'reboot' - the memory image will be saved by the kernel and 63 the system will be rebooted. 64 65 Additionally, /sys/power/disk can be used to turn on one of the 66 two testing modes of the suspend-to-disk mechanism: 'testproc' 67 or 'test'. If the suspend-to-disk mechanism is in the 68 'testproc' mode, writing 'disk' to /sys/power/state will cause 69 the kernel to disable nonboot CPUs and freeze tasks, wait for 5 70 seconds, unfreeze tasks and enable nonboot CPUs. If it is in 71 the 'test' mode, writing 'disk' to /sys/power/state will cause 72 the kernel to disable nonboot CPUs and freeze tasks, shrink 73 memory, suspend devices, wait for 5 seconds, resume devices, 74 unfreeze tasks and enable nonboot CPUs. Then, we are able to 75 look in the log messages and work out, for example, which code 76 is being slow and which device drivers are misbehaving. 77 78 The suspend-to-disk method may be chosen by writing to this 79 file one of the accepted strings: 80 81 - 'firmware' 82 - 'platform' 83 - 'shutdown' 84 - 'reboot' 85 - 'testproc' 86 - 'test' 87 88 It will only change to 'firmware' or 'platform' if the system 89 supports that. 90 91What: /sys/power/image_size 92Date: August 2006 93Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 94Description: 95 The /sys/power/image_size file controls the size of the image 96 created by the suspend-to-disk mechanism. It can be written a 97 string representing a non-negative integer that will be used 98 as an upper limit of the image size, in bytes. The kernel's 99 suspend-to-disk code will do its best to ensure the image size 100 will not exceed this number. However, if it turns out to be 101 impossible, the kernel will try to suspend anyway using the 102 smallest image possible. In particular, if "0" is written to 103 this file, the suspend image will be as small as possible. 104 105 Reading from this file will display the current image size 106 limit, which is set to around 2/5 of available RAM by default. 107 108What: /sys/power/pm_trace 109Date: August 2006 110Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 111Description: 112 The /sys/power/pm_trace file controls the code which saves the 113 last PM event point in the RTC across reboots, so that you can 114 debug a machine that just hangs during suspend (or more 115 commonly, during resume). Namely, the RTC is only used to save 116 the last PM event point if this file contains '1'. Initially 117 it contains '0' which may be changed to '1' by writing a 118 string representing a nonzero integer into it. 119 120 To use this debugging feature you should attempt to suspend 121 the machine, then reboot it and run:: 122 123 dmesg -s 1000000 | grep 'hash matches' 124 125 If you do not get any matches (or they appear to be false 126 positives), it is possible that the last PM event point 127 referred to a device created by a loadable kernel module. In 128 this case cat /sys/power/pm_trace_dev_match (see below) after 129 your system is started up and the kernel modules are loaded. 130 131 CAUTION: Using it will cause your machine's real-time (CMOS) 132 clock to be set to a random invalid time after a resume. 133 134What; /sys/power/pm_trace_dev_match 135Date: October 2010 136Contact: James Hogan <jhogan@kernel.org> 137Description: 138 The /sys/power/pm_trace_dev_match file contains the name of the 139 device associated with the last PM event point saved in the RTC 140 across reboots when pm_trace has been used. More precisely it 141 contains the list of current devices (including those 142 registered by loadable kernel modules since boot) which match 143 the device hash in the RTC at boot, with a newline after each 144 one. 145 146 The advantage of this file over the hash matches printed to the 147 kernel log (see /sys/power/pm_trace), is that it includes 148 devices created after boot by loadable kernel modules. 149 150 Due to the small hash size necessary to fit in the RTC, it is 151 possible that more than one device matches the hash, in which 152 case further investigation is required to determine which 153 device is causing the problem. Note that genuine RTC clock 154 values (such as when pm_trace has not been used), can still 155 match a device and output its name here. 156 157What: /sys/power/pm_async 158Date: January 2009 159Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 160Description: 161 The /sys/power/pm_async file controls the switch allowing the 162 user space to enable or disable asynchronous suspend and resume 163 of devices. If enabled, this feature will cause some device 164 drivers' suspend and resume callbacks to be executed in parallel 165 with each other and with the main suspend thread. It is enabled 166 if this file contains "1", which is the default. It may be 167 disabled by writing "0" to this file, in which case all devices 168 will be suspended and resumed synchronously. 169 170What: /sys/power/wakeup_count 171Date: July 2010 172Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 173Description: 174 The /sys/power/wakeup_count file allows user space to put the 175 system into a sleep state while taking into account the 176 concurrent arrival of wakeup events. Reading from it returns 177 the current number of registered wakeup events and it blocks if 178 some wakeup events are being processed at the time the file is 179 read from. Writing to it will only succeed if the current 180 number of wakeup events is equal to the written value and, if 181 successful, will make the kernel abort a subsequent transition 182 to a sleep state if any wakeup events are reported after the 183 write has returned. 184 185What: /sys/power/reserved_size 186Date: May 2011 187Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 188Description: 189 The /sys/power/reserved_size file allows user space to control 190 the amount of memory reserved for allocations made by device 191 drivers during the "device freeze" stage of hibernation. It can 192 be written a string representing a non-negative integer that 193 will be used as the amount of memory to reserve for allocations 194 made by device drivers' "freeze" callbacks, in bytes. 195 196 Reading from this file will display the current value, which is 197 set to 1 MB by default. 198 199What: /sys/power/autosleep 200Date: April 2012 201Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 202Description: 203 The /sys/power/autosleep file can be written one of the strings 204 returned by reads from /sys/power/state. If that happens, a 205 work item attempting to trigger a transition of the system to 206 the sleep state represented by that string is queued up. This 207 attempt will only succeed if there are no active wakeup sources 208 in the system at that time. After every execution, regardless 209 of whether or not the attempt to put the system to sleep has 210 succeeded, the work item requeues itself until user space 211 writes "off" to /sys/power/autosleep. 212 213 Reading from this file causes the last string successfully 214 written to it to be returned. 215 216What: /sys/power/wake_lock 217Date: February 2012 218Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 219Description: 220 The /sys/power/wake_lock file allows user space to create 221 wakeup source objects and activate them on demand (if one of 222 those wakeup sources is active, reads from the 223 /sys/power/wakeup_count file block or return false). When a 224 string without white space is written to /sys/power/wake_lock, 225 it will be assumed to represent a wakeup source name. If there 226 is a wakeup source object with that name, it will be activated 227 (unless active already). Otherwise, a new wakeup source object 228 will be registered, assigned the given name and activated. 229 If a string written to /sys/power/wake_lock contains white 230 space, the part of the string preceding the white space will be 231 regarded as a wakeup source name and handled as descrived above. 232 The other part of the string will be regarded as a timeout (in 233 nanoseconds) such that the wakeup source will be automatically 234 deactivated after it has expired. The timeout, if present, is 235 set regardless of the current state of the wakeup source object 236 in question. 237 238 Reads from this file return a string consisting of the names of 239 wakeup sources created with the help of it that are active at 240 the moment, separated with spaces. 241 242 243What: /sys/power/wake_unlock 244Date: February 2012 245Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 246Description: 247 The /sys/power/wake_unlock file allows user space to deactivate 248 wakeup sources created with the help of /sys/power/wake_lock. 249 When a string is written to /sys/power/wake_unlock, it will be 250 assumed to represent the name of a wakeup source to deactivate. 251 252 If a wakeup source object of that name exists and is active at 253 the moment, it will be deactivated. 254 255 Reads from this file return a string consisting of the names of 256 wakeup sources created with the help of /sys/power/wake_lock 257 that are inactive at the moment, separated with spaces. 258 259What: /sys/power/pm_print_times 260Date: May 2012 261Contact: Sameer Nanda <snanda@chromium.org> 262Description: 263 The /sys/power/pm_print_times file allows user space to 264 control whether the time taken by devices to suspend and 265 resume is printed. These prints are useful for hunting down 266 devices that take too long to suspend or resume. 267 268 Writing a "1" enables this printing while writing a "0" 269 disables it. The default value is "0". Reading from this file 270 will display the current value. 271 272What: /sys/power/pm_wakeup_irq 273Date: April 2015 274Contact: Alexandra Yates <alexandra.yates@linux.intel.org> 275Description: 276 The /sys/power/pm_wakeup_irq file reports to user space the IRQ 277 number of the first wakeup interrupt (that is, the first 278 interrupt from an IRQ line armed for system wakeup) seen by the 279 kernel during the most recent system suspend/resume cycle. 280 281 This output is useful for system wakeup diagnostics of spurious 282 wakeup interrupts. 283 284What: /sys/power/pm_debug_messages 285Date: July 2017 286Contact: Rafael J. Wysocki <rjw@rjwysocki.net> 287Description: 288 The /sys/power/pm_debug_messages file controls the printing 289 of debug messages from the system suspend/hiberbation 290 infrastructure to the kernel log. 291 292 Writing a "1" to this file enables the debug messages and 293 writing a "0" (default) to it disables them. Reads from 294 this file return the current value. 295 296What: /sys/power/resume_offset 297Date: April 2018 298Contact: Mario Limonciello <mario.limonciello@outlook.com> 299Description: 300 This file is used for telling the kernel an offset into a disk 301 to use when hibernating the system such as with a swap file. 302 303 Reads from this file will display the current offset 304 the kernel will be using on the next hibernation 305 attempt. 306 307 Using this sysfs file will override any values that were 308 set using the kernel command line for disk offset. 309 310What: /sys/power/suspend_stats 311Date: July 2019 312Contact: Kalesh Singh <kaleshsingh96@gmail.com> 313Description: 314 The /sys/power/suspend_stats directory contains suspend related 315 statistics. 316 317What: /sys/power/suspend_stats/success 318Date: July 2019 319Contact: Kalesh Singh <kaleshsingh96@gmail.com> 320Description: 321 The /sys/power/suspend_stats/success file contains the number 322 of times entering system sleep state succeeded. 323 324What: /sys/power/suspend_stats/fail 325Date: July 2019 326Contact: Kalesh Singh <kaleshsingh96@gmail.com> 327Description: 328 The /sys/power/suspend_stats/fail file contains the number 329 of times entering system sleep state failed. 330 331What: /sys/power/suspend_stats/failed_freeze 332Date: July 2019 333Contact: Kalesh Singh <kaleshsingh96@gmail.com> 334Description: 335 The /sys/power/suspend_stats/failed_freeze file contains the 336 number of times freezing processes failed. 337 338What: /sys/power/suspend_stats/failed_prepare 339Date: July 2019 340Contact: Kalesh Singh <kaleshsingh96@gmail.com> 341Description: 342 The /sys/power/suspend_stats/failed_prepare file contains the 343 number of times preparing all non-sysdev devices for 344 a system PM transition failed. 345 346What: /sys/power/suspend_stats/failed_resume 347Date: July 2019 348Contact: Kalesh Singh <kaleshsingh96@gmail.com> 349Description: 350 The /sys/power/suspend_stats/failed_resume file contains the 351 number of times executing "resume" callbacks of 352 non-sysdev devices failed. 353 354What: /sys/power/suspend_stats/failed_resume_early 355Date: July 2019 356Contact: Kalesh Singh <kaleshsingh96@gmail.com> 357Description: 358 The /sys/power/suspend_stats/failed_resume_early file contains 359 the number of times executing "early resume" callbacks 360 of devices failed. 361 362What: /sys/power/suspend_stats/failed_resume_noirq 363Date: July 2019 364Contact: Kalesh Singh <kaleshsingh96@gmail.com> 365Description: 366 The /sys/power/suspend_stats/failed_resume_noirq file contains 367 the number of times executing "noirq resume" callbacks 368 of devices failed. 369 370What: /sys/power/suspend_stats/failed_suspend 371Date: July 2019 372Contact: Kalesh Singh <kaleshsingh96@gmail.com> 373Description: 374 The /sys/power/suspend_stats/failed_suspend file contains 375 the number of times executing "suspend" callbacks 376 of all non-sysdev devices failed. 377 378What: /sys/power/suspend_stats/failed_suspend_late 379Date: July 2019 380Contact: Kalesh Singh <kaleshsingh96@gmail.com> 381Description: 382 The /sys/power/suspend_stats/failed_suspend_late file contains 383 the number of times executing "late suspend" callbacks 384 of all devices failed. 385 386What: /sys/power/suspend_stats/failed_suspend_noirq 387Date: July 2019 388Contact: Kalesh Singh <kaleshsingh96@gmail.com> 389Description: 390 The /sys/power/suspend_stats/failed_suspend_noirq file contains 391 the number of times executing "noirq suspend" callbacks 392 of all devices failed. 393 394What: /sys/power/suspend_stats/last_failed_dev 395Date: July 2019 396Contact: Kalesh Singh <kaleshsingh96@gmail.com> 397Description: 398 The /sys/power/suspend_stats/last_failed_dev file contains 399 the last device for which a suspend/resume callback failed. 400 401What: /sys/power/suspend_stats/last_failed_errno 402Date: July 2019 403Contact: Kalesh Singh <kaleshsingh96@gmail.com> 404Description: 405 The /sys/power/suspend_stats/last_failed_errno file contains 406 the errno of the last failed attempt at entering 407 system sleep state. 408 409What: /sys/power/suspend_stats/last_failed_step 410Date: July 2019 411Contact: Kalesh Singh <kaleshsingh96@gmail.com> 412Description: 413 The /sys/power/suspend_stats/last_failed_step file contains 414 the last failed step in the suspend/resume path. 415 416What: /sys/power/sync_on_suspend 417Date: October 2019 418Contact: Jonas Meurer <jonas@freesources.org> 419Description: 420 This file controls whether or not the kernel will sync() 421 filesystems during system suspend (after freezing user space 422 and before suspending devices). 423 424 Writing a "1" to this file enables the sync() and writing a "0" 425 disables it. Reads from the file return the current value. 426 The default is "1" if the build-time "SUSPEND_SKIP_SYNC" config 427 flag is unset, or "0" otherwise. 428