1What:		/sys/devices/system/cpu/
2Date:		pre-git history
3Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
4Description:
5		A collection of both global and individual CPU attributes
6
7		Individual CPU attributes are contained in subdirectories
8		named by the kernel's logical CPU number, e.g.:
9
10		/sys/devices/system/cpu/cpuX/
11
12What:		/sys/devices/system/cpu/kernel_max
13		/sys/devices/system/cpu/offline
14		/sys/devices/system/cpu/online
15		/sys/devices/system/cpu/possible
16		/sys/devices/system/cpu/present
17Date:		December 2008
18Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
19Description:	CPU topology files that describe kernel limits related to
20		hotplug. Briefly:
21
22		kernel_max: the maximum cpu index allowed by the kernel
23		configuration.
24
25		offline: cpus that are not online because they have been
26		HOTPLUGGED off or exceed the limit of cpus allowed by the
27		kernel configuration (kernel_max above).
28
29		online: cpus that are online and being scheduled.
30
31		possible: cpus that have been allocated resources and can be
32		brought online if they are present.
33
34		present: cpus that have been identified as being present in
35		the system.
36
37		See Documentation/admin-guide/cputopology.rst for more information.
38
39
40What:		/sys/devices/system/cpu/probe
41		/sys/devices/system/cpu/release
42Date:		November 2009
43Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
44Description:	Dynamic addition and removal of CPU's.  This is not hotplug
45		removal, this is meant complete removal/addition of the CPU
46		from the system.
47
48		probe: writes to this file will dynamically add a CPU to the
49		system.  Information written to the file to add CPU's is
50		architecture specific.
51
52		release: writes to this file dynamically remove a CPU from
53		the system.  Information written to the file to remove CPU's
54		is architecture specific.
55
56What:		/sys/devices/system/cpu/cpuX/node
57Date:		October 2009
58Contact:	Linux memory management mailing list <linux-mm@kvack.org>
59Description:	Discover NUMA node a CPU belongs to
60
61		When CONFIG_NUMA is enabled, a symbolic link that points
62		to the corresponding NUMA node directory.
63
64		For example, the following symlink is created for cpu42
65		in NUMA node 2:
66
67		/sys/devices/system/cpu/cpu42/node2 -> ../../node/node2
68
69
70What:		/sys/devices/system/cpu/cpuX/topology/core_id
71		/sys/devices/system/cpu/cpuX/topology/core_siblings
72		/sys/devices/system/cpu/cpuX/topology/core_siblings_list
73		/sys/devices/system/cpu/cpuX/topology/physical_package_id
74		/sys/devices/system/cpu/cpuX/topology/thread_siblings
75		/sys/devices/system/cpu/cpuX/topology/thread_siblings_list
76Date:		December 2008
77Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
78Description:	CPU topology files that describe a logical CPU's relationship
79		to other cores and threads in the same physical package.
80
81		One cpuX directory is created per logical CPU in the system,
82		e.g. /sys/devices/system/cpu/cpu42/.
83
84		Briefly, the files above are:
85
86		core_id: the CPU core ID of cpuX. Typically it is the
87		hardware platform's identifier (rather than the kernel's).
88		The actual value is architecture and platform dependent.
89
90		core_siblings: internal kernel map of cpuX's hardware threads
91		within the same physical_package_id.
92
93		core_siblings_list: human-readable list of the logical CPU
94		numbers within the same physical_package_id as cpuX.
95
96		physical_package_id: physical package id of cpuX. Typically
97		corresponds to a physical socket number, but the actual value
98		is architecture and platform dependent.
99
100		thread_siblings: internal kernel map of cpuX's hardware
101		threads within the same core as cpuX
102
103		thread_siblings_list: human-readable list of cpuX's hardware
104		threads within the same core as cpuX
105
106		See Documentation/admin-guide/cputopology.rst for more information.
107
108
109What:		/sys/devices/system/cpu/cpuidle/available_governors
110		/sys/devices/system/cpu/cpuidle/current_driver
111		/sys/devices/system/cpu/cpuidle/current_governor
112		/sys/devices/system/cpu/cpuidle/current_governer_ro
113Date:		September 2007
114Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
115Description:	Discover cpuidle policy and mechanism
116
117		Various CPUs today support multiple idle levels that are
118		differentiated by varying exit latencies and power
119		consumption during idle.
120
121		Idle policy (governor) is differentiated from idle mechanism
122		(driver).
123
124		available_governors: (RO) displays a space separated list of
125		available governors.
126
127		current_driver: (RO) displays current idle mechanism.
128
129		current_governor: (RW) displays current idle policy. Users can
130		switch the governor at runtime by writing to this file.
131
132		current_governor_ro: (RO) displays current idle policy.
133
134		See Documentation/admin-guide/pm/cpuidle.rst and
135		Documentation/driver-api/pm/cpuidle.rst for more information.
136
137
138What:		/sys/devices/system/cpu/cpuX/cpuidle/state<N>/name
139		/sys/devices/system/cpu/cpuX/cpuidle/stateN/latency
140		/sys/devices/system/cpu/cpuX/cpuidle/stateN/power
141		/sys/devices/system/cpu/cpuX/cpuidle/stateN/time
142		/sys/devices/system/cpu/cpuX/cpuidle/stateN/usage
143		/sys/devices/system/cpu/cpuX/cpuidle/stateN/above
144		/sys/devices/system/cpu/cpuX/cpuidle/stateN/below
145Date:		September 2007
146KernelVersion:	v2.6.24
147Contact:	Linux power management list <linux-pm@vger.kernel.org>
148Description:
149		The directory /sys/devices/system/cpu/cpuX/cpuidle contains per
150		logical CPU specific cpuidle information for each online cpu X.
151		The processor idle states which are available for use have the
152		following attributes:
153
154		======== ==== =================================================
155		name:	 (RO) Name of the idle state (string).
156
157		latency: (RO) The latency to exit out of this idle state (in
158			      microseconds).
159
160		power:   (RO) The power consumed while in this idle state (in
161			      milliwatts).
162
163		time:    (RO) The total time spent in this idle state
164			      (in microseconds).
165
166		usage:	 (RO) Number of times this state was entered (a count).
167
168		above:	 (RO) Number of times this state was entered, but the
169			      observed CPU idle duration was too short for it
170			      (a count).
171
172		below:	 (RO) Number of times this state was entered, but the
173			      observed CPU idle duration was too long for it
174			      (a count).
175		======== ==== =================================================
176
177What:		/sys/devices/system/cpu/cpuX/cpuidle/state<N>/desc
178Date:		February 2008
179KernelVersion:	v2.6.25
180Contact:	Linux power management list <linux-pm@vger.kernel.org>
181Description:
182		(RO) A small description about the idle state (string).
183
184
185What:		/sys/devices/system/cpu/cpuX/cpuidle/state<N>/disable
186Date:		March 2012
187KernelVersion:	v3.10
188Contact:	Linux power management list <linux-pm@vger.kernel.org>
189Description:
190		(RW) Option to disable this idle state (bool). The behavior and
191		the effect of the disable variable depends on the implementation
192		of a particular governor. In the ladder governor, for example,
193		it is not coherent, i.e. if one is disabling a light state, then
194		all deeper states are disabled as well, but the disable variable
195		does not reflect it. Likewise, if one enables a deep state but a
196		lighter state still is disabled, then this has no effect.
197
198What:		/sys/devices/system/cpu/cpuX/cpuidle/state<N>/default_status
199Date:		December 2019
200KernelVersion:	v5.6
201Contact:	Linux power management list <linux-pm@vger.kernel.org>
202Description:
203		(RO) The default status of this state, "enabled" or "disabled".
204
205What:		/sys/devices/system/cpu/cpuX/cpuidle/state<N>/residency
206Date:		March 2014
207KernelVersion:	v3.15
208Contact:	Linux power management list <linux-pm@vger.kernel.org>
209Description:
210		(RO) Display the target residency i.e. the minimum amount of
211		time (in microseconds) this cpu should spend in this idle state
212		to make the transition worth the effort.
213
214What:		/sys/devices/system/cpu/cpuX/cpuidle/state<N>/s2idle/
215Date:		March 2018
216KernelVersion:	v4.17
217Contact:	Linux power management list <linux-pm@vger.kernel.org>
218Description:
219		Idle state usage statistics related to suspend-to-idle.
220
221		This attribute group is only present for states that can be
222		used in suspend-to-idle with suspended timekeeping.
223
224What:		/sys/devices/system/cpu/cpuX/cpuidle/state<N>/s2idle/time
225Date:		March 2018
226KernelVersion:	v4.17
227Contact:	Linux power management list <linux-pm@vger.kernel.org>
228Description:
229		Total time spent by the CPU in suspend-to-idle (with scheduler
230		tick suspended) after requesting this state.
231
232What:		/sys/devices/system/cpu/cpuX/cpuidle/state<N>/s2idle/usage
233Date:		March 2018
234KernelVersion:	v4.17
235Contact:	Linux power management list <linux-pm@vger.kernel.org>
236Description:
237		Total number of times this state has been requested by the CPU
238		while entering suspend-to-idle.
239
240What:		/sys/devices/system/cpu/cpuX/cpufreq/*
241Date:		pre-git history
242Contact:	linux-pm@vger.kernel.org
243Description:	Discover and change clock speed of CPUs
244
245		Clock scaling allows you to change the clock speed of the
246		CPUs on the fly. This is a nice method to save battery
247		power, because the lower the clock speed, the less power
248		the CPU consumes.
249
250		There are many knobs to tweak in this directory.
251
252		See files in Documentation/cpu-freq/ for more information.
253
254
255What:		/sys/devices/system/cpu/cpuX/cpufreq/freqdomain_cpus
256Date:		June 2013
257Contact:	linux-pm@vger.kernel.org
258Description:	Discover CPUs in the same CPU frequency coordination domain
259
260		freqdomain_cpus is the list of CPUs (online+offline) that share
261		the same clock/freq domain (possibly at the hardware level).
262		That information may be hidden from the cpufreq core and the
263		value of related_cpus may be different from freqdomain_cpus. This
264		attribute is useful for user space DVFS controllers to get better
265		power/performance results for platforms using acpi-cpufreq.
266
267		This file is only present if the acpi-cpufreq or the cppc-cpufreq
268		drivers are in use.
269
270
271What:		/sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1}
272Date:		August 2008
273KernelVersion:	2.6.27
274Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
275Description:	Disable L3 cache indices
276
277		These files exist in every CPU's cache/index3 directory. Each
278		cache_disable_{0,1} file corresponds to one disable slot which
279		can be used to disable a cache index. Reading from these files
280		on a processor with this functionality will return the currently
281		disabled index for that node. There is one L3 structure per
282		node, or per internal node on MCM machines. Writing a valid
283		index to one of these files will cause the specified cache
284		index to be disabled.
285
286		All AMD processors with L3 caches provide this functionality.
287		For details, see BKDGs at
288                https://www.amd.com/en/support/tech-docs?keyword=bios+kernel
289
290
291What:		/sys/devices/system/cpu/cpufreq/boost
292Date:		August 2012
293Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
294Description:	Processor frequency boosting control
295
296		This switch controls the boost setting for the whole system.
297		Boosting allows the CPU and the firmware to run at a frequency
298		beyond it's nominal limit.
299
300		More details can be found in
301		Documentation/admin-guide/pm/cpufreq.rst
302
303
304What:		/sys/devices/system/cpu/cpuX/crash_notes
305		/sys/devices/system/cpu/cpuX/crash_notes_size
306Date:		April 2013
307Contact:	kexec@lists.infradead.org
308Description:	address and size of the percpu note.
309
310		crash_notes: the physical address of the memory that holds the
311		note of cpuX.
312
313		crash_notes_size: size of the note of cpuX.
314
315
316What:		/sys/devices/system/cpu/intel_pstate/max_perf_pct
317		/sys/devices/system/cpu/intel_pstate/min_perf_pct
318		/sys/devices/system/cpu/intel_pstate/no_turbo
319Date:		February 2013
320Contact:	linux-pm@vger.kernel.org
321Description:	Parameters for the Intel P-state driver
322
323		Logic for selecting the current P-state in Intel
324		Sandybridge+ processors. The three knobs control
325		limits for the P-state that will be requested by the
326		driver.
327
328		max_perf_pct: limits the maximum P state that will be requested by
329		the driver stated as a percentage of the available performance.
330
331		min_perf_pct: limits the minimum P state that will be requested by
332		the driver stated as a percentage of the available performance.
333
334		no_turbo: limits the driver to selecting P states below the turbo
335		frequency range.
336
337		More details can be found in
338		Documentation/admin-guide/pm/intel_pstate.rst
339
340What:		/sys/devices/system/cpu/cpu*/cache/index*/<set_of_attributes_mentioned_below>
341Date:		July 2014(documented, existed before August 2008)
342Contact:	Sudeep Holla <sudeep.holla@arm.com>
343		Linux kernel mailing list <linux-kernel@vger.kernel.org>
344Description:	Parameters for the CPU cache attributes
345
346		allocation_policy:
347			- WriteAllocate:
348					allocate a memory location to a cache line
349					on a cache miss because of a write
350			- ReadAllocate:
351					allocate a memory location to a cache line
352					on a cache miss because of a read
353			- ReadWriteAllocate:
354					both writeallocate and readallocate
355
356		attributes:
357			    LEGACY used only on IA64 and is same as write_policy
358
359		coherency_line_size:
360				     the minimum amount of data in bytes that gets
361				     transferred from memory to cache
362
363		level:
364			the cache hierarchy in the multi-level cache configuration
365
366		number_of_sets:
367				total number of sets in the cache, a set is a
368				collection of cache lines with the same cache index
369
370		physical_line_partition:
371				number of physical cache line per cache tag
372
373		shared_cpu_list:
374				the list of logical cpus sharing the cache
375
376		shared_cpu_map:
377				logical cpu mask containing the list of cpus sharing
378				the cache
379
380		size:
381			the total cache size in kB
382
383		type:
384			- Instruction: cache that only holds instructions
385			- Data: cache that only caches data
386			- Unified: cache that holds both data and instructions
387
388		ways_of_associativity:
389			degree of freedom in placing a particular block
390			of memory in the cache
391
392		write_policy:
393			- WriteThrough:
394					data is written to both the cache line
395					and to the block in the lower-level memory
396			- WriteBack:
397				     data is written only to the cache line and
398				     the modified cache line is written to main
399				     memory only when it is replaced
400
401
402What:		/sys/devices/system/cpu/cpu*/cache/index*/id
403Date:		September 2016
404Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
405Description:	Cache id
406
407		The id provides a unique number for a specific instance of
408		a cache of a particular type. E.g. there may be a level
409		3 unified cache on each socket in a server and we may
410		assign them ids 0, 1, 2, ...
411
412		Note that id value can be non-contiguous. E.g. level 1
413		caches typically exist per core, but there may not be a
414		power of two cores on a socket, so these caches may be
415		numbered 0, 1, 2, 3, 4, 5, 8, 9, 10, ...
416
417What:		/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats
418		/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/turbo_stat
419		/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/sub_turbo_stat
420		/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/unthrottle
421		/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/powercap
422		/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overtemp
423		/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/supply_fault
424		/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overcurrent
425		/sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/occ_reset
426Date:		March 2016
427Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
428		Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
429Description:	POWERNV CPUFreq driver's frequency throttle stats directory and
430		attributes
431
432		'cpuX/cpufreq/throttle_stats' directory contains the CPU frequency
433		throttle stat attributes for the chip. The throttle stats of a cpu
434		is common across all the cpus belonging to a chip. Below are the
435		throttle attributes exported in the 'throttle_stats' directory:
436
437		- turbo_stat : This file gives the total number of times the max
438		  frequency is throttled to lower frequency in turbo (at and above
439		  nominal frequency) range of frequencies.
440
441		- sub_turbo_stat : This file gives the total number of times the
442		  max frequency is throttled to lower frequency in sub-turbo(below
443		  nominal frequency) range of frequencies.
444
445		- unthrottle : This file gives the total number of times the max
446		  frequency is unthrottled after being throttled.
447
448		- powercap : This file gives the total number of times the max
449		  frequency is throttled due to 'Power Capping'.
450
451		- overtemp : This file gives the total number of times the max
452		  frequency is throttled due to 'CPU Over Temperature'.
453
454		- supply_fault : This file gives the total number of times the
455		  max frequency is throttled due to 'Power Supply Failure'.
456
457		- overcurrent : This file gives the total number of times the
458		  max frequency is throttled due to 'Overcurrent'.
459
460		- occ_reset : This file gives the total number of times the max
461		  frequency is throttled due to 'OCC Reset'.
462
463		The sysfs attributes representing different throttle reasons like
464		powercap, overtemp, supply_fault, overcurrent and occ_reset map to
465		the reasons provided by OCC firmware for throttling the frequency.
466
467What:		/sys/devices/system/cpu/cpufreq/policyX/throttle_stats
468		/sys/devices/system/cpu/cpufreq/policyX/throttle_stats/turbo_stat
469		/sys/devices/system/cpu/cpufreq/policyX/throttle_stats/sub_turbo_stat
470		/sys/devices/system/cpu/cpufreq/policyX/throttle_stats/unthrottle
471		/sys/devices/system/cpu/cpufreq/policyX/throttle_stats/powercap
472		/sys/devices/system/cpu/cpufreq/policyX/throttle_stats/overtemp
473		/sys/devices/system/cpu/cpufreq/policyX/throttle_stats/supply_fault
474		/sys/devices/system/cpu/cpufreq/policyX/throttle_stats/overcurrent
475		/sys/devices/system/cpu/cpufreq/policyX/throttle_stats/occ_reset
476Date:		March 2016
477Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
478		Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
479Description:	POWERNV CPUFreq driver's frequency throttle stats directory and
480		attributes
481
482		'policyX/throttle_stats' directory and all the attributes are same as
483		the /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats directory and
484		attributes which give the frequency throttle information of the chip.
485
486What:		/sys/devices/system/cpu/cpuX/regs/
487		/sys/devices/system/cpu/cpuX/regs/identification/
488		/sys/devices/system/cpu/cpuX/regs/identification/midr_el1
489		/sys/devices/system/cpu/cpuX/regs/identification/revidr_el1
490Date:		June 2016
491Contact:	Linux ARM Kernel Mailing list <linux-arm-kernel@lists.infradead.org>
492Description:	AArch64 CPU registers
493
494		'identification' directory exposes the CPU ID registers for
495		identifying model and revision of the CPU.
496
497What:		/sys/devices/system/cpu/aarch32_el0
498Date:		May 2021
499Contact:	Linux ARM Kernel Mailing list <linux-arm-kernel@lists.infradead.org>
500Description:	Identifies the subset of CPUs in the system that can execute
501		AArch32 (32-bit ARM) applications. If present, the same format as
502		/sys/devices/system/cpu/{offline,online,possible,present} is used.
503		If absent, then all or none of the CPUs can execute AArch32
504		applications and execve() will behave accordingly.
505
506What:		/sys/devices/system/cpu/cpuX/cpu_capacity
507Date:		December 2016
508Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
509Description:	information about CPUs heterogeneity.
510
511		cpu_capacity: capacity of cpuX.
512
513What:		/sys/devices/system/cpu/vulnerabilities
514		/sys/devices/system/cpu/vulnerabilities/meltdown
515		/sys/devices/system/cpu/vulnerabilities/spectre_v1
516		/sys/devices/system/cpu/vulnerabilities/spectre_v2
517		/sys/devices/system/cpu/vulnerabilities/spec_store_bypass
518		/sys/devices/system/cpu/vulnerabilities/l1tf
519		/sys/devices/system/cpu/vulnerabilities/mds
520		/sys/devices/system/cpu/vulnerabilities/srbds
521		/sys/devices/system/cpu/vulnerabilities/tsx_async_abort
522		/sys/devices/system/cpu/vulnerabilities/itlb_multihit
523Date:		January 2018
524Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
525Description:	Information about CPU vulnerabilities
526
527		The files are named after the code names of CPU
528		vulnerabilities. The output of those files reflects the
529		state of the CPUs in the system. Possible output values:
530
531		================  ==============================================
532		"Not affected"	  CPU is not affected by the vulnerability
533		"Vulnerable"	  CPU is affected and no mitigation in effect
534		"Mitigation: $M"  CPU is affected and mitigation $M is in effect
535		================  ==============================================
536
537		See also: Documentation/admin-guide/hw-vuln/index.rst
538
539What:		/sys/devices/system/cpu/smt
540		/sys/devices/system/cpu/smt/active
541		/sys/devices/system/cpu/smt/control
542Date:		June 2018
543Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
544Description:	Control Symmetric Multi Threading (SMT)
545
546		active:  Tells whether SMT is active (enabled and siblings online)
547
548		control: Read/write interface to control SMT. Possible
549			 values:
550
551			 ================ =========================================
552			 "on"		  SMT is enabled
553			 "off"		  SMT is disabled
554			 "forceoff"	  SMT is force disabled. Cannot be changed.
555			 "notsupported"   SMT is not supported by the CPU
556			 "notimplemented" SMT runtime toggling is not
557					  implemented for the architecture
558			 ================ =========================================
559
560			 If control status is "forceoff" or "notsupported" writes
561			 are rejected.
562
563What:		/sys/devices/system/cpu/cpuX/power/energy_perf_bias
564Date:		March 2019
565Contact:	linux-pm@vger.kernel.org
566Description:	Intel Energy and Performance Bias Hint (EPB)
567
568		EPB for the given CPU in a sliding scale 0 - 15, where a value
569		of 0 corresponds to a hint preference for highest performance
570		and a value of 15 corresponds to the maximum energy savings.
571
572		In order to change the EPB value for the CPU, write either
573		a number in the 0 - 15 sliding scale above, or one of the
574		strings: "performance", "balance-performance", "normal",
575		"balance-power", "power" (that represent values reflected by
576		their meaning), to this attribute.
577
578		This attribute is present for all online CPUs supporting the
579		Intel EPB feature.
580
581What:		/sys/devices/system/cpu/umwait_control
582		/sys/devices/system/cpu/umwait_control/enable_c02
583		/sys/devices/system/cpu/umwait_control/max_time
584Date:		May 2019
585Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
586Description:	Umwait control
587
588		enable_c02: Read/write interface to control umwait C0.2 state
589			Read returns C0.2 state status:
590				0: C0.2 is disabled
591				1: C0.2 is enabled
592
593			Write 'y' or '1'  or 'on' to enable C0.2 state.
594			Write 'n' or '0'  or 'off' to disable C0.2 state.
595
596			The interface is case insensitive.
597
598		max_time: Read/write interface to control umwait maximum time
599			  in TSC-quanta that the CPU can reside in either C0.1
600			  or C0.2 state. The time is an unsigned 32-bit number.
601			  Note that a value of zero means there is no limit.
602			  Low order two bits must be zero.
603
604What:		/sys/devices/system/cpu/svm
605Date:		August 2019
606Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
607		Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
608Description:	Secure Virtual Machine
609
610		If 1, it means the system is using the Protected Execution
611		Facility in POWER9 and newer processors. i.e., it is a Secure
612		Virtual Machine.
613
614What:		/sys/devices/system/cpu/cpuX/purr
615Date:		Apr 2005
616Contact:	Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
617Description:	PURR ticks for this CPU since the system boot.
618
619		The Processor Utilization Resources Register (PURR) is
620		a 64-bit counter which provides an estimate of the
621		resources used by the CPU thread. The contents of this
622		register increases monotonically. This sysfs interface
623		exposes the number of PURR ticks for cpuX.
624
625What: 		/sys/devices/system/cpu/cpuX/spurr
626Date:		Dec 2006
627Contact:	Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
628Description:	SPURR ticks for this CPU since the system boot.
629
630		The Scaled Processor Utilization Resources Register
631		(SPURR) is a 64-bit counter that provides a frequency
632		invariant estimate of the resources used by the CPU
633		thread. The contents of this register increases
634		monotonically. This sysfs interface exposes the number
635		of SPURR ticks for cpuX.
636
637What: 		/sys/devices/system/cpu/cpuX/idle_purr
638Date:		Apr 2020
639Contact:	Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
640Description:	PURR ticks for cpuX when it was idle.
641
642		This sysfs interface exposes the number of PURR ticks
643		for cpuX when it was idle.
644
645What: 		/sys/devices/system/cpu/cpuX/idle_spurr
646Date:		Apr 2020
647Contact:	Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
648Description:	SPURR ticks for cpuX when it was idle.
649
650		This sysfs interface exposes the number of SPURR ticks
651		for cpuX when it was idle.
652
653What: 		/sys/devices/system/cpu/cpuX/mte_tcf_preferred
654Date:		July 2021
655Contact:	Linux ARM Kernel Mailing list <linux-arm-kernel@lists.infradead.org>
656Description:	Preferred MTE tag checking mode
657
658		When a user program specifies more than one MTE tag checking
659		mode, this sysfs node is used to specify which mode should
660		be preferred when scheduling a task on that CPU. Possible
661		values:
662
663		================  ==============================================
664		"sync"	  	  Prefer synchronous mode
665		"async"	  	  Prefer asynchronous mode
666		================  ==============================================
667
668		See also: Documentation/arm64/memory-tagging-extension.rst
669
670What:		/sys/devices/system/cpu/nohz_full
671Date:		Apr 2015
672Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
673Description:
674		(RO) the list of CPUs that are in nohz_full mode.
675		These CPUs are set by boot parameter "nohz_full=".
676
677What:		/sys/devices/system/cpu/isolated
678Date:		Apr 2015
679Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
680Description:
681		(RO) the list of CPUs that are isolated and don't
682		participate in load balancing. These CPUs are set by
683		boot parameter "isolcpus=".
684