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Based on kernel version 3.13. Page generated on 2014-01-20 22:04 EST.

1	Documentation for /proc/sys/kernel/*	kernel version 2.2.10
2		(c) 1998, 1999,  Rik van Riel <riel@nl.linux.org>
3		(c) 2009,        Shen Feng<shen@cn.fujitsu.com>
4	
5	For general info and legal blurb, please look in README.
6	
7	==============================================================
8	
9	This file contains documentation for the sysctl files in
10	/proc/sys/kernel/ and is valid for Linux kernel version 2.2.
11	
12	The files in this directory can be used to tune and monitor
13	miscellaneous and general things in the operation of the Linux
14	kernel. Since some of the files _can_ be used to screw up your
15	system, it is advisable to read both documentation and source
16	before actually making adjustments.
17	
18	Currently, these files might (depending on your configuration)
19	show up in /proc/sys/kernel:
20	
21	- acct
22	- acpi_video_flags
23	- auto_msgmni
24	- bootloader_type	     [ X86 only ]
25	- bootloader_version	     [ X86 only ]
26	- callhome		     [ S390 only ]
27	- cap_last_cap
28	- core_pattern
29	- core_pipe_limit
30	- core_uses_pid
31	- ctrl-alt-del
32	- dmesg_restrict
33	- domainname
34	- hostname
35	- hotplug
36	- kptr_restrict
37	- kstack_depth_to_print       [ X86 only ]
38	- l2cr                        [ PPC only ]
39	- modprobe                    ==> Documentation/debugging-modules.txt
40	- modules_disabled
41	- msg_next_id		      [ sysv ipc ]
42	- msgmax
43	- msgmnb
44	- msgmni
45	- nmi_watchdog
46	- osrelease
47	- ostype
48	- overflowgid
49	- overflowuid
50	- panic
51	- panic_on_oops
52	- panic_on_unrecovered_nmi
53	- panic_on_stackoverflow
54	- pid_max
55	- powersave-nap               [ PPC only ]
56	- printk
57	- printk_delay
58	- printk_ratelimit
59	- printk_ratelimit_burst
60	- randomize_va_space
61	- real-root-dev               ==> Documentation/initrd.txt
62	- reboot-cmd                  [ SPARC only ]
63	- rtsig-max
64	- rtsig-nr
65	- sem
66	- sem_next_id		      [ sysv ipc ]
67	- sg-big-buff                 [ generic SCSI device (sg) ]
68	- shm_next_id		      [ sysv ipc ]
69	- shm_rmid_forced
70	- shmall
71	- shmmax                      [ sysv ipc ]
72	- shmmni
73	- stop-a                      [ SPARC only ]
74	- sysrq                       ==> Documentation/sysrq.txt
75	- tainted
76	- threads-max
77	- unknown_nmi_panic
78	- watchdog_thresh
79	- version
80	
81	==============================================================
82	
83	acct:
84	
85	highwater lowwater frequency
86	
87	If BSD-style process accounting is enabled these values control
88	its behaviour. If free space on filesystem where the log lives
89	goes below <lowwater>% accounting suspends. If free space gets
90	above <highwater>% accounting resumes. <Frequency> determines
91	how often do we check the amount of free space (value is in
92	seconds). Default:
93	4 2 30
94	That is, suspend accounting if there left <= 2% free; resume it
95	if we got >=4%; consider information about amount of free space
96	valid for 30 seconds.
97	
98	==============================================================
99	
100	acpi_video_flags:
101	
102	flags
103	
104	See Doc*/kernel/power/video.txt, it allows mode of video boot to be
105	set during run time.
106	
107	==============================================================
108	
109	auto_msgmni:
110	
111	Enables/Disables automatic recomputing of msgmni upon memory add/remove
112	or upon ipc namespace creation/removal (see the msgmni description
113	above). Echoing "1" into this file enables msgmni automatic recomputing.
114	Echoing "0" turns it off. auto_msgmni default value is 1.
115	
116	
117	==============================================================
118	
119	bootloader_type:
120	
121	x86 bootloader identification
122	
123	This gives the bootloader type number as indicated by the bootloader,
124	shifted left by 4, and OR'd with the low four bits of the bootloader
125	version.  The reason for this encoding is that this used to match the
126	type_of_loader field in the kernel header; the encoding is kept for
127	backwards compatibility.  That is, if the full bootloader type number
128	is 0x15 and the full version number is 0x234, this file will contain
129	the value 340 = 0x154.
130	
131	See the type_of_loader and ext_loader_type fields in
132	Documentation/x86/boot.txt for additional information.
133	
134	==============================================================
135	
136	bootloader_version:
137	
138	x86 bootloader version
139	
140	The complete bootloader version number.  In the example above, this
141	file will contain the value 564 = 0x234.
142	
143	See the type_of_loader and ext_loader_ver fields in
144	Documentation/x86/boot.txt for additional information.
145	
146	==============================================================
147	
148	callhome:
149	
150	Controls the kernel's callhome behavior in case of a kernel panic.
151	
152	The s390 hardware allows an operating system to send a notification
153	to a service organization (callhome) in case of an operating system panic.
154	
155	When the value in this file is 0 (which is the default behavior)
156	nothing happens in case of a kernel panic. If this value is set to "1"
157	the complete kernel oops message is send to the IBM customer service
158	organization in case the mainframe the Linux operating system is running
159	on has a service contract with IBM.
160	
161	==============================================================
162	
163	cap_last_cap
164	
165	Highest valid capability of the running kernel.  Exports
166	CAP_LAST_CAP from the kernel.
167	
168	==============================================================
169	
170	core_pattern:
171	
172	core_pattern is used to specify a core dumpfile pattern name.
173	. max length 128 characters; default value is "core"
174	. core_pattern is used as a pattern template for the output filename;
175	  certain string patterns (beginning with '%') are substituted with
176	  their actual values.
177	. backward compatibility with core_uses_pid:
178		If core_pattern does not include "%p" (default does not)
179		and core_uses_pid is set, then .PID will be appended to
180		the filename.
181	. corename format specifiers:
182		%<NUL>	'%' is dropped
183		%%	output one '%'
184		%p	pid
185		%P	global pid (init PID namespace)
186		%u	uid
187		%g	gid
188		%d	dump mode, matches PR_SET_DUMPABLE and
189			/proc/sys/fs/suid_dumpable
190		%s	signal number
191		%t	UNIX time of dump
192		%h	hostname
193		%e	executable filename (may be shortened)
194		%E	executable path
195		%<OTHER> both are dropped
196	. If the first character of the pattern is a '|', the kernel will treat
197	  the rest of the pattern as a command to run.  The core dump will be
198	  written to the standard input of that program instead of to a file.
199	
200	==============================================================
201	
202	core_pipe_limit:
203	
204	This sysctl is only applicable when core_pattern is configured to pipe
205	core files to a user space helper (when the first character of
206	core_pattern is a '|', see above).  When collecting cores via a pipe
207	to an application, it is occasionally useful for the collecting
208	application to gather data about the crashing process from its
209	/proc/pid directory.  In order to do this safely, the kernel must wait
210	for the collecting process to exit, so as not to remove the crashing
211	processes proc files prematurely.  This in turn creates the
212	possibility that a misbehaving userspace collecting process can block
213	the reaping of a crashed process simply by never exiting.  This sysctl
214	defends against that.  It defines how many concurrent crashing
215	processes may be piped to user space applications in parallel.  If
216	this value is exceeded, then those crashing processes above that value
217	are noted via the kernel log and their cores are skipped.  0 is a
218	special value, indicating that unlimited processes may be captured in
219	parallel, but that no waiting will take place (i.e. the collecting
220	process is not guaranteed access to /proc/<crashing pid>/).  This
221	value defaults to 0.
222	
223	==============================================================
224	
225	core_uses_pid:
226	
227	The default coredump filename is "core".  By setting
228	core_uses_pid to 1, the coredump filename becomes core.PID.
229	If core_pattern does not include "%p" (default does not)
230	and core_uses_pid is set, then .PID will be appended to
231	the filename.
232	
233	==============================================================
234	
235	ctrl-alt-del:
236	
237	When the value in this file is 0, ctrl-alt-del is trapped and
238	sent to the init(1) program to handle a graceful restart.
239	When, however, the value is > 0, Linux's reaction to a Vulcan
240	Nerve Pinch (tm) will be an immediate reboot, without even
241	syncing its dirty buffers.
242	
243	Note: when a program (like dosemu) has the keyboard in 'raw'
244	mode, the ctrl-alt-del is intercepted by the program before it
245	ever reaches the kernel tty layer, and it's up to the program
246	to decide what to do with it.
247	
248	==============================================================
249	
250	dmesg_restrict:
251	
252	This toggle indicates whether unprivileged users are prevented
253	from using dmesg(8) to view messages from the kernel's log buffer.
254	When dmesg_restrict is set to (0) there are no restrictions. When
255	dmesg_restrict is set set to (1), users must have CAP_SYSLOG to use
256	dmesg(8).
257	
258	The kernel config option CONFIG_SECURITY_DMESG_RESTRICT sets the
259	default value of dmesg_restrict.
260	
261	==============================================================
262	
263	domainname & hostname:
264	
265	These files can be used to set the NIS/YP domainname and the
266	hostname of your box in exactly the same way as the commands
267	domainname and hostname, i.e.:
268	# echo "darkstar" > /proc/sys/kernel/hostname
269	# echo "mydomain" > /proc/sys/kernel/domainname
270	has the same effect as
271	# hostname "darkstar"
272	# domainname "mydomain"
273	
274	Note, however, that the classic darkstar.frop.org has the
275	hostname "darkstar" and DNS (Internet Domain Name Server)
276	domainname "frop.org", not to be confused with the NIS (Network
277	Information Service) or YP (Yellow Pages) domainname. These two
278	domain names are in general different. For a detailed discussion
279	see the hostname(1) man page.
280	
281	==============================================================
282	
283	hotplug:
284	
285	Path for the hotplug policy agent.
286	Default value is "/sbin/hotplug".
287	
288	==============================================================
289	
290	kptr_restrict:
291	
292	This toggle indicates whether restrictions are placed on
293	exposing kernel addresses via /proc and other interfaces.
294	
295	When kptr_restrict is set to (0), the default, there are no restrictions.
296	
297	When kptr_restrict is set to (1), kernel pointers printed using the %pK
298	format specifier will be replaced with 0's unless the user has CAP_SYSLOG
299	and effective user and group ids are equal to the real ids. This is
300	because %pK checks are done at read() time rather than open() time, so
301	if permissions are elevated between the open() and the read() (e.g via
302	a setuid binary) then %pK will not leak kernel pointers to unprivileged
303	users. Note, this is a temporary solution only. The correct long-term
304	solution is to do the permission checks at open() time. Consider removing
305	world read permissions from files that use %pK, and using dmesg_restrict
306	to protect against uses of %pK in dmesg(8) if leaking kernel pointer
307	values to unprivileged users is a concern.
308	
309	When kptr_restrict is set to (2), kernel pointers printed using
310	%pK will be replaced with 0's regardless of privileges.
311	
312	==============================================================
313	
314	kstack_depth_to_print: (X86 only)
315	
316	Controls the number of words to print when dumping the raw
317	kernel stack.
318	
319	==============================================================
320	
321	l2cr: (PPC only)
322	
323	This flag controls the L2 cache of G3 processor boards. If
324	0, the cache is disabled. Enabled if nonzero.
325	
326	==============================================================
327	
328	modules_disabled:
329	
330	A toggle value indicating if modules are allowed to be loaded
331	in an otherwise modular kernel.  This toggle defaults to off
332	(0), but can be set true (1).  Once true, modules can be
333	neither loaded nor unloaded, and the toggle cannot be set back
334	to false.
335	
336	==============================================================
337	
338	msg_next_id, sem_next_id, and shm_next_id:
339	
340	These three toggles allows to specify desired id for next allocated IPC
341	object: message, semaphore or shared memory respectively.
342	
343	By default they are equal to -1, which means generic allocation logic.
344	Possible values to set are in range {0..INT_MAX}.
345	
346	Notes:
347	1) kernel doesn't guarantee, that new object will have desired id. So,
348	it's up to userspace, how to handle an object with "wrong" id.
349	2) Toggle with non-default value will be set back to -1 by kernel after
350	successful IPC object allocation.
351	
352	==============================================================
353	
354	nmi_watchdog:
355	
356	Enables/Disables the NMI watchdog on x86 systems. When the value is
357	non-zero the NMI watchdog is enabled and will continuously test all
358	online cpus to determine whether or not they are still functioning
359	properly. Currently, passing "nmi_watchdog=" parameter at boot time is
360	required for this function to work.
361	
362	If LAPIC NMI watchdog method is in use (nmi_watchdog=2 kernel
363	parameter), the NMI watchdog shares registers with oprofile. By
364	disabling the NMI watchdog, oprofile may have more registers to
365	utilize.
366	
367	==============================================================
368	
369	numa_balancing
370	
371	Enables/disables automatic page fault based NUMA memory
372	balancing. Memory is moved automatically to nodes
373	that access it often.
374	
375	Enables/disables automatic NUMA memory balancing. On NUMA machines, there
376	is a performance penalty if remote memory is accessed by a CPU. When this
377	feature is enabled the kernel samples what task thread is accessing memory
378	by periodically unmapping pages and later trapping a page fault. At the
379	time of the page fault, it is determined if the data being accessed should
380	be migrated to a local memory node.
381	
382	The unmapping of pages and trapping faults incur additional overhead that
383	ideally is offset by improved memory locality but there is no universal
384	guarantee. If the target workload is already bound to NUMA nodes then this
385	feature should be disabled. Otherwise, if the system overhead from the
386	feature is too high then the rate the kernel samples for NUMA hinting
387	faults may be controlled by the numa_balancing_scan_period_min_ms,
388	numa_balancing_scan_delay_ms, numa_balancing_scan_period_max_ms,
389	numa_balancing_scan_size_mb, numa_balancing_settle_count sysctls and
390	numa_balancing_migrate_deferred.
391	
392	==============================================================
393	
394	numa_balancing_scan_period_min_ms, numa_balancing_scan_delay_ms,
395	numa_balancing_scan_period_max_ms, numa_balancing_scan_size_mb
396	
397	Automatic NUMA balancing scans tasks address space and unmaps pages to
398	detect if pages are properly placed or if the data should be migrated to a
399	memory node local to where the task is running.  Every "scan delay" the task
400	scans the next "scan size" number of pages in its address space. When the
401	end of the address space is reached the scanner restarts from the beginning.
402	
403	In combination, the "scan delay" and "scan size" determine the scan rate.
404	When "scan delay" decreases, the scan rate increases.  The scan delay and
405	hence the scan rate of every task is adaptive and depends on historical
406	behaviour. If pages are properly placed then the scan delay increases,
407	otherwise the scan delay decreases.  The "scan size" is not adaptive but
408	the higher the "scan size", the higher the scan rate.
409	
410	Higher scan rates incur higher system overhead as page faults must be
411	trapped and potentially data must be migrated. However, the higher the scan
412	rate, the more quickly a tasks memory is migrated to a local node if the
413	workload pattern changes and minimises performance impact due to remote
414	memory accesses. These sysctls control the thresholds for scan delays and
415	the number of pages scanned.
416	
417	numa_balancing_scan_period_min_ms is the minimum time in milliseconds to
418	scan a tasks virtual memory. It effectively controls the maximum scanning
419	rate for each task.
420	
421	numa_balancing_scan_delay_ms is the starting "scan delay" used for a task
422	when it initially forks.
423	
424	numa_balancing_scan_period_max_ms is the maximum time in milliseconds to
425	scan a tasks virtual memory. It effectively controls the minimum scanning
426	rate for each task.
427	
428	numa_balancing_scan_size_mb is how many megabytes worth of pages are
429	scanned for a given scan.
430	
431	numa_balancing_settle_count is how many scan periods must complete before
432	the schedule balancer stops pushing the task towards a preferred node. This
433	gives the scheduler a chance to place the task on an alternative node if the
434	preferred node is overloaded.
435	
436	numa_balancing_migrate_deferred is how many page migrations get skipped
437	unconditionally, after a page migration is skipped because a page is shared
438	with other tasks. This reduces page migration overhead, and determines
439	how much stronger the "move task near its memory" policy scheduler becomes,
440	versus the "move memory near its task" memory management policy, for workloads
441	with shared memory.
442	
443	==============================================================
444	
445	osrelease, ostype & version:
446	
447	# cat osrelease
448	2.1.88
449	# cat ostype
450	Linux
451	# cat version
452	#5 Wed Feb 25 21:49:24 MET 1998
453	
454	The files osrelease and ostype should be clear enough. Version
455	needs a little more clarification however. The '#5' means that
456	this is the fifth kernel built from this source base and the
457	date behind it indicates the time the kernel was built.
458	The only way to tune these values is to rebuild the kernel :-)
459	
460	==============================================================
461	
462	overflowgid & overflowuid:
463	
464	if your architecture did not always support 32-bit UIDs (i.e. arm,
465	i386, m68k, sh, and sparc32), a fixed UID and GID will be returned to
466	applications that use the old 16-bit UID/GID system calls, if the
467	actual UID or GID would exceed 65535.
468	
469	These sysctls allow you to change the value of the fixed UID and GID.
470	The default is 65534.
471	
472	==============================================================
473	
474	panic:
475	
476	The value in this file represents the number of seconds the kernel
477	waits before rebooting on a panic. When you use the software watchdog,
478	the recommended setting is 60.
479	
480	==============================================================
481	
482	panic_on_unrecovered_nmi:
483	
484	The default Linux behaviour on an NMI of either memory or unknown is
485	to continue operation. For many environments such as scientific
486	computing it is preferable that the box is taken out and the error
487	dealt with than an uncorrected parity/ECC error get propagated.
488	
489	A small number of systems do generate NMI's for bizarre random reasons
490	such as power management so the default is off. That sysctl works like
491	the existing panic controls already in that directory.
492	
493	==============================================================
494	
495	panic_on_oops:
496	
497	Controls the kernel's behaviour when an oops or BUG is encountered.
498	
499	0: try to continue operation
500	
501	1: panic immediately.  If the `panic' sysctl is also non-zero then the
502	   machine will be rebooted.
503	
504	==============================================================
505	
506	panic_on_stackoverflow:
507	
508	Controls the kernel's behavior when detecting the overflows of
509	kernel, IRQ and exception stacks except a user stack.
510	This file shows up if CONFIG_DEBUG_STACKOVERFLOW is enabled.
511	
512	0: try to continue operation.
513	
514	1: panic immediately.
515	
516	==============================================================
517	
518	perf_cpu_time_max_percent:
519	
520	Hints to the kernel how much CPU time it should be allowed to
521	use to handle perf sampling events.  If the perf subsystem
522	is informed that its samples are exceeding this limit, it
523	will drop its sampling frequency to attempt to reduce its CPU
524	usage.
525	
526	Some perf sampling happens in NMIs.  If these samples
527	unexpectedly take too long to execute, the NMIs can become
528	stacked up next to each other so much that nothing else is
529	allowed to execute.
530	
531	0: disable the mechanism.  Do not monitor or correct perf's
532	   sampling rate no matter how CPU time it takes.
533	
534	1-100: attempt to throttle perf's sample rate to this
535	   percentage of CPU.  Note: the kernel calculates an
536	   "expected" length of each sample event.  100 here means
537	   100% of that expected length.  Even if this is set to
538	   100, you may still see sample throttling if this
539	   length is exceeded.  Set to 0 if you truly do not care
540	   how much CPU is consumed.
541	
542	==============================================================
543	
544	
545	pid_max:
546	
547	PID allocation wrap value.  When the kernel's next PID value
548	reaches this value, it wraps back to a minimum PID value.
549	PIDs of value pid_max or larger are not allocated.
550	
551	==============================================================
552	
553	ns_last_pid:
554	
555	The last pid allocated in the current (the one task using this sysctl
556	lives in) pid namespace. When selecting a pid for a next task on fork
557	kernel tries to allocate a number starting from this one.
558	
559	==============================================================
560	
561	powersave-nap: (PPC only)
562	
563	If set, Linux-PPC will use the 'nap' mode of powersaving,
564	otherwise the 'doze' mode will be used.
565	
566	==============================================================
567	
568	printk:
569	
570	The four values in printk denote: console_loglevel,
571	default_message_loglevel, minimum_console_loglevel and
572	default_console_loglevel respectively.
573	
574	These values influence printk() behavior when printing or
575	logging error messages. See 'man 2 syslog' for more info on
576	the different loglevels.
577	
578	- console_loglevel: messages with a higher priority than
579	  this will be printed to the console
580	- default_message_loglevel: messages without an explicit priority
581	  will be printed with this priority
582	- minimum_console_loglevel: minimum (highest) value to which
583	  console_loglevel can be set
584	- default_console_loglevel: default value for console_loglevel
585	
586	==============================================================
587	
588	printk_delay:
589	
590	Delay each printk message in printk_delay milliseconds
591	
592	Value from 0 - 10000 is allowed.
593	
594	==============================================================
595	
596	printk_ratelimit:
597	
598	Some warning messages are rate limited. printk_ratelimit specifies
599	the minimum length of time between these messages (in jiffies), by
600	default we allow one every 5 seconds.
601	
602	A value of 0 will disable rate limiting.
603	
604	==============================================================
605	
606	printk_ratelimit_burst:
607	
608	While long term we enforce one message per printk_ratelimit
609	seconds, we do allow a burst of messages to pass through.
610	printk_ratelimit_burst specifies the number of messages we can
611	send before ratelimiting kicks in.
612	
613	==============================================================
614	
615	randomize_va_space:
616	
617	This option can be used to select the type of process address
618	space randomization that is used in the system, for architectures
619	that support this feature.
620	
621	0 - Turn the process address space randomization off.  This is the
622	    default for architectures that do not support this feature anyways,
623	    and kernels that are booted with the "norandmaps" parameter.
624	
625	1 - Make the addresses of mmap base, stack and VDSO page randomized.
626	    This, among other things, implies that shared libraries will be
627	    loaded to random addresses.  Also for PIE-linked binaries, the
628	    location of code start is randomized.  This is the default if the
629	    CONFIG_COMPAT_BRK option is enabled.
630	
631	2 - Additionally enable heap randomization.  This is the default if
632	    CONFIG_COMPAT_BRK is disabled.
633	
634	    There are a few legacy applications out there (such as some ancient
635	    versions of libc.so.5 from 1996) that assume that brk area starts
636	    just after the end of the code+bss.  These applications break when
637	    start of the brk area is randomized.  There are however no known
638	    non-legacy applications that would be broken this way, so for most
639	    systems it is safe to choose full randomization.
640	
641	    Systems with ancient and/or broken binaries should be configured
642	    with CONFIG_COMPAT_BRK enabled, which excludes the heap from process
643	    address space randomization.
644	
645	==============================================================
646	
647	reboot-cmd: (Sparc only)
648	
649	??? This seems to be a way to give an argument to the Sparc
650	ROM/Flash boot loader. Maybe to tell it what to do after
651	rebooting. ???
652	
653	==============================================================
654	
655	rtsig-max & rtsig-nr:
656	
657	The file rtsig-max can be used to tune the maximum number
658	of POSIX realtime (queued) signals that can be outstanding
659	in the system.
660	
661	rtsig-nr shows the number of RT signals currently queued.
662	
663	==============================================================
664	
665	sg-big-buff:
666	
667	This file shows the size of the generic SCSI (sg) buffer.
668	You can't tune it just yet, but you could change it on
669	compile time by editing include/scsi/sg.h and changing
670	the value of SG_BIG_BUFF.
671	
672	There shouldn't be any reason to change this value. If
673	you can come up with one, you probably know what you
674	are doing anyway :)
675	
676	==============================================================
677	
678	shmall:
679	
680	This parameter sets the total amount of shared memory pages that
681	can be used system wide. Hence, SHMALL should always be at least
682	ceil(shmmax/PAGE_SIZE).
683	
684	If you are not sure what the default PAGE_SIZE is on your Linux
685	system, you can run the following command:
686	
687	# getconf PAGE_SIZE
688	
689	==============================================================
690	
691	shmmax:
692	
693	This value can be used to query and set the run time limit
694	on the maximum shared memory segment size that can be created.
695	Shared memory segments up to 1Gb are now supported in the
696	kernel.  This value defaults to SHMMAX.
697	
698	==============================================================
699	
700	shm_rmid_forced:
701	
702	Linux lets you set resource limits, including how much memory one
703	process can consume, via setrlimit(2).  Unfortunately, shared memory
704	segments are allowed to exist without association with any process, and
705	thus might not be counted against any resource limits.  If enabled,
706	shared memory segments are automatically destroyed when their attach
707	count becomes zero after a detach or a process termination.  It will
708	also destroy segments that were created, but never attached to, on exit
709	from the process.  The only use left for IPC_RMID is to immediately
710	destroy an unattached segment.  Of course, this breaks the way things are
711	defined, so some applications might stop working.  Note that this
712	feature will do you no good unless you also configure your resource
713	limits (in particular, RLIMIT_AS and RLIMIT_NPROC).  Most systems don't
714	need this.
715	
716	Note that if you change this from 0 to 1, already created segments
717	without users and with a dead originative process will be destroyed.
718	
719	==============================================================
720	
721	tainted:
722	
723	Non-zero if the kernel has been tainted.  Numeric values, which
724	can be ORed together:
725	
726	   1 - A module with a non-GPL license has been loaded, this
727	       includes modules with no license.
728	       Set by modutils >= 2.4.9 and module-init-tools.
729	   2 - A module was force loaded by insmod -f.
730	       Set by modutils >= 2.4.9 and module-init-tools.
731	   4 - Unsafe SMP processors: SMP with CPUs not designed for SMP.
732	   8 - A module was forcibly unloaded from the system by rmmod -f.
733	  16 - A hardware machine check error occurred on the system.
734	  32 - A bad page was discovered on the system.
735	  64 - The user has asked that the system be marked "tainted".  This
736	       could be because they are running software that directly modifies
737	       the hardware, or for other reasons.
738	 128 - The system has died.
739	 256 - The ACPI DSDT has been overridden with one supplied by the user
740	        instead of using the one provided by the hardware.
741	 512 - A kernel warning has occurred.
742	1024 - A module from drivers/staging was loaded.
743	2048 - The system is working around a severe firmware bug.
744	4096 - An out-of-tree module has been loaded.
745	
746	==============================================================
747	
748	unknown_nmi_panic:
749	
750	The value in this file affects behavior of handling NMI. When the
751	value is non-zero, unknown NMI is trapped and then panic occurs. At
752	that time, kernel debugging information is displayed on console.
753	
754	NMI switch that most IA32 servers have fires unknown NMI up, for
755	example.  If a system hangs up, try pressing the NMI switch.
756	
757	==============================================================
758	
759	watchdog_thresh:
760	
761	This value can be used to control the frequency of hrtimer and NMI
762	events and the soft and hard lockup thresholds. The default threshold
763	is 10 seconds.
764	
765	The softlockup threshold is (2 * watchdog_thresh). Setting this
766	tunable to zero will disable lockup detection altogether.
767	
768	==============================================================
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