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1da177e4 LT |
1 | Documentation for /proc/sys/kernel/* kernel version 2.2.10 |
2 | (c) 1998, 1999, Rik van Riel <riel@nl.linux.org> | |
760df93e | 3 | (c) 2009, Shen Feng<shen@cn.fujitsu.com> |
1da177e4 LT |
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: | |
807094c0 | 20 | |
1da177e4 | 21 | - acct |
807094c0 BP |
22 | - acpi_video_flags |
23 | - auto_msgmni | |
d75757ab PA |
24 | - bootloader_type [ X86 only ] |
25 | - bootloader_version [ X86 only ] | |
c114728a | 26 | - callhome [ S390 only ] |
73efc039 | 27 | - cap_last_cap |
1da177e4 | 28 | - core_pattern |
a293980c | 29 | - core_pipe_limit |
1da177e4 LT |
30 | - core_uses_pid |
31 | - ctrl-alt-del | |
eaf06b24 | 32 | - dmesg_restrict |
1da177e4 LT |
33 | - domainname |
34 | - hostname | |
35 | - hotplug | |
455cd5ab | 36 | - kptr_restrict |
0741f4d2 | 37 | - kstack_depth_to_print [ X86 only ] |
1da177e4 | 38 | - l2cr [ PPC only ] |
ac76cff2 | 39 | - modprobe ==> Documentation/debugging-modules.txt |
3d43321b | 40 | - modules_disabled |
1da177e4 LT |
41 | - msgmax |
42 | - msgmnb | |
43 | - msgmni | |
760df93e | 44 | - nmi_watchdog |
1da177e4 LT |
45 | - osrelease |
46 | - ostype | |
47 | - overflowgid | |
48 | - overflowuid | |
49 | - panic | |
807094c0 BP |
50 | - panic_on_oops |
51 | - panic_on_unrecovered_nmi | |
55af7796 | 52 | - panic_on_stackoverflow |
1da177e4 LT |
53 | - pid_max |
54 | - powersave-nap [ PPC only ] | |
55 | - printk | |
807094c0 BP |
56 | - printk_delay |
57 | - printk_ratelimit | |
58 | - printk_ratelimit_burst | |
1ec7fd50 | 59 | - randomize_va_space |
1da177e4 LT |
60 | - real-root-dev ==> Documentation/initrd.txt |
61 | - reboot-cmd [ SPARC only ] | |
62 | - rtsig-max | |
63 | - rtsig-nr | |
64 | - sem | |
65 | - sg-big-buff [ generic SCSI device (sg) ] | |
b34a6b1d | 66 | - shm_rmid_forced |
1da177e4 LT |
67 | - shmall |
68 | - shmmax [ sysv ipc ] | |
69 | - shmmni | |
807094c0 | 70 | - softlockup_thresh |
1da177e4 LT |
71 | - stop-a [ SPARC only ] |
72 | - sysrq ==> Documentation/sysrq.txt | |
73 | - tainted | |
74 | - threads-max | |
760df93e | 75 | - unknown_nmi_panic |
1da177e4 LT |
76 | - version |
77 | ||
78 | ============================================================== | |
79 | ||
80 | acct: | |
81 | ||
82 | highwater lowwater frequency | |
83 | ||
84 | If BSD-style process accounting is enabled these values control | |
85 | its behaviour. If free space on filesystem where the log lives | |
86 | goes below <lowwater>% accounting suspends. If free space gets | |
87 | above <highwater>% accounting resumes. <Frequency> determines | |
88 | how often do we check the amount of free space (value is in | |
89 | seconds). Default: | |
90 | 4 2 30 | |
91 | That is, suspend accounting if there left <= 2% free; resume it | |
92 | if we got >=4%; consider information about amount of free space | |
93 | valid for 30 seconds. | |
94 | ||
807094c0 BP |
95 | ============================================================== |
96 | ||
97 | acpi_video_flags: | |
98 | ||
99 | flags | |
100 | ||
101 | See Doc*/kernel/power/video.txt, it allows mode of video boot to be | |
102 | set during run time. | |
103 | ||
104 | ============================================================== | |
105 | ||
106 | auto_msgmni: | |
107 | ||
108 | Enables/Disables automatic recomputing of msgmni upon memory add/remove | |
109 | or upon ipc namespace creation/removal (see the msgmni description | |
110 | above). Echoing "1" into this file enables msgmni automatic recomputing. | |
111 | Echoing "0" turns it off. auto_msgmni default value is 1. | |
112 | ||
113 | ||
1da177e4 LT |
114 | ============================================================== |
115 | ||
d75757ab PA |
116 | bootloader_type: |
117 | ||
118 | x86 bootloader identification | |
119 | ||
120 | This gives the bootloader type number as indicated by the bootloader, | |
121 | shifted left by 4, and OR'd with the low four bits of the bootloader | |
122 | version. The reason for this encoding is that this used to match the | |
123 | type_of_loader field in the kernel header; the encoding is kept for | |
124 | backwards compatibility. That is, if the full bootloader type number | |
125 | is 0x15 and the full version number is 0x234, this file will contain | |
126 | the value 340 = 0x154. | |
127 | ||
128 | See the type_of_loader and ext_loader_type fields in | |
129 | Documentation/x86/boot.txt for additional information. | |
130 | ||
131 | ============================================================== | |
132 | ||
133 | bootloader_version: | |
134 | ||
135 | x86 bootloader version | |
136 | ||
137 | The complete bootloader version number. In the example above, this | |
138 | file will contain the value 564 = 0x234. | |
139 | ||
140 | See the type_of_loader and ext_loader_ver fields in | |
141 | Documentation/x86/boot.txt for additional information. | |
142 | ||
143 | ============================================================== | |
144 | ||
c114728a HJP |
145 | callhome: |
146 | ||
147 | Controls the kernel's callhome behavior in case of a kernel panic. | |
148 | ||
149 | The s390 hardware allows an operating system to send a notification | |
150 | to a service organization (callhome) in case of an operating system panic. | |
151 | ||
152 | When the value in this file is 0 (which is the default behavior) | |
153 | nothing happens in case of a kernel panic. If this value is set to "1" | |
154 | the complete kernel oops message is send to the IBM customer service | |
155 | organization in case the mainframe the Linux operating system is running | |
156 | on has a service contract with IBM. | |
157 | ||
158 | ============================================================== | |
159 | ||
73efc039 DB |
160 | cap_last_cap |
161 | ||
162 | Highest valid capability of the running kernel. Exports | |
163 | CAP_LAST_CAP from the kernel. | |
164 | ||
165 | ============================================================== | |
166 | ||
1da177e4 LT |
167 | core_pattern: |
168 | ||
169 | core_pattern is used to specify a core dumpfile pattern name. | |
cd081041 | 170 | . max length 128 characters; default value is "core" |
1da177e4 LT |
171 | . core_pattern is used as a pattern template for the output filename; |
172 | certain string patterns (beginning with '%') are substituted with | |
173 | their actual values. | |
174 | . backward compatibility with core_uses_pid: | |
175 | If core_pattern does not include "%p" (default does not) | |
176 | and core_uses_pid is set, then .PID will be appended to | |
177 | the filename. | |
178 | . corename format specifiers: | |
179 | %<NUL> '%' is dropped | |
180 | %% output one '%' | |
181 | %p pid | |
182 | %u uid | |
183 | %g gid | |
12a2b4b2 ON |
184 | %d dump mode, matches PR_SET_DUMPABLE and |
185 | /proc/sys/fs/suid_dumpable | |
1da177e4 LT |
186 | %s signal number |
187 | %t UNIX time of dump | |
188 | %h hostname | |
57cc083a JS |
189 | %e executable filename (may be shortened) |
190 | %E executable path | |
1da177e4 | 191 | %<OTHER> both are dropped |
cd081041 MU |
192 | . If the first character of the pattern is a '|', the kernel will treat |
193 | the rest of the pattern as a command to run. The core dump will be | |
194 | written to the standard input of that program instead of to a file. | |
1da177e4 LT |
195 | |
196 | ============================================================== | |
197 | ||
a293980c NH |
198 | core_pipe_limit: |
199 | ||
807094c0 BP |
200 | This sysctl is only applicable when core_pattern is configured to pipe |
201 | core files to a user space helper (when the first character of | |
202 | core_pattern is a '|', see above). When collecting cores via a pipe | |
203 | to an application, it is occasionally useful for the collecting | |
204 | application to gather data about the crashing process from its | |
205 | /proc/pid directory. In order to do this safely, the kernel must wait | |
206 | for the collecting process to exit, so as not to remove the crashing | |
207 | processes proc files prematurely. This in turn creates the | |
208 | possibility that a misbehaving userspace collecting process can block | |
209 | the reaping of a crashed process simply by never exiting. This sysctl | |
210 | defends against that. It defines how many concurrent crashing | |
211 | processes may be piped to user space applications in parallel. If | |
212 | this value is exceeded, then those crashing processes above that value | |
213 | are noted via the kernel log and their cores are skipped. 0 is a | |
214 | special value, indicating that unlimited processes may be captured in | |
215 | parallel, but that no waiting will take place (i.e. the collecting | |
216 | process is not guaranteed access to /proc/<crashing pid>/). This | |
217 | value defaults to 0. | |
a293980c NH |
218 | |
219 | ============================================================== | |
220 | ||
1da177e4 LT |
221 | core_uses_pid: |
222 | ||
223 | The default coredump filename is "core". By setting | |
224 | core_uses_pid to 1, the coredump filename becomes core.PID. | |
225 | If core_pattern does not include "%p" (default does not) | |
226 | and core_uses_pid is set, then .PID will be appended to | |
227 | the filename. | |
228 | ||
229 | ============================================================== | |
230 | ||
231 | ctrl-alt-del: | |
232 | ||
233 | When the value in this file is 0, ctrl-alt-del is trapped and | |
234 | sent to the init(1) program to handle a graceful restart. | |
235 | When, however, the value is > 0, Linux's reaction to a Vulcan | |
236 | Nerve Pinch (tm) will be an immediate reboot, without even | |
237 | syncing its dirty buffers. | |
238 | ||
239 | Note: when a program (like dosemu) has the keyboard in 'raw' | |
240 | mode, the ctrl-alt-del is intercepted by the program before it | |
241 | ever reaches the kernel tty layer, and it's up to the program | |
242 | to decide what to do with it. | |
243 | ||
244 | ============================================================== | |
245 | ||
eaf06b24 DR |
246 | dmesg_restrict: |
247 | ||
807094c0 BP |
248 | This toggle indicates whether unprivileged users are prevented |
249 | from using dmesg(8) to view messages from the kernel's log buffer. | |
250 | When dmesg_restrict is set to (0) there are no restrictions. When | |
38ef4c2e | 251 | dmesg_restrict is set set to (1), users must have CAP_SYSLOG to use |
eaf06b24 DR |
252 | dmesg(8). |
253 | ||
807094c0 BP |
254 | The kernel config option CONFIG_SECURITY_DMESG_RESTRICT sets the |
255 | default value of dmesg_restrict. | |
eaf06b24 DR |
256 | |
257 | ============================================================== | |
258 | ||
1da177e4 LT |
259 | domainname & hostname: |
260 | ||
261 | These files can be used to set the NIS/YP domainname and the | |
262 | hostname of your box in exactly the same way as the commands | |
263 | domainname and hostname, i.e.: | |
264 | # echo "darkstar" > /proc/sys/kernel/hostname | |
265 | # echo "mydomain" > /proc/sys/kernel/domainname | |
266 | has the same effect as | |
267 | # hostname "darkstar" | |
268 | # domainname "mydomain" | |
269 | ||
270 | Note, however, that the classic darkstar.frop.org has the | |
271 | hostname "darkstar" and DNS (Internet Domain Name Server) | |
272 | domainname "frop.org", not to be confused with the NIS (Network | |
273 | Information Service) or YP (Yellow Pages) domainname. These two | |
274 | domain names are in general different. For a detailed discussion | |
275 | see the hostname(1) man page. | |
276 | ||
277 | ============================================================== | |
278 | ||
279 | hotplug: | |
280 | ||
281 | Path for the hotplug policy agent. | |
282 | Default value is "/sbin/hotplug". | |
283 | ||
284 | ============================================================== | |
285 | ||
455cd5ab DR |
286 | kptr_restrict: |
287 | ||
288 | This toggle indicates whether restrictions are placed on | |
289 | exposing kernel addresses via /proc and other interfaces. When | |
290 | kptr_restrict is set to (0), there are no restrictions. When | |
291 | kptr_restrict is set to (1), the default, kernel pointers | |
292 | printed using the %pK format specifier will be replaced with 0's | |
293 | unless the user has CAP_SYSLOG. When kptr_restrict is set to | |
294 | (2), kernel pointers printed using %pK will be replaced with 0's | |
295 | regardless of privileges. | |
296 | ||
297 | ============================================================== | |
298 | ||
0741f4d2 CE |
299 | kstack_depth_to_print: (X86 only) |
300 | ||
301 | Controls the number of words to print when dumping the raw | |
302 | kernel stack. | |
303 | ||
304 | ============================================================== | |
305 | ||
807094c0 BP |
306 | l2cr: (PPC only) |
307 | ||
308 | This flag controls the L2 cache of G3 processor boards. If | |
309 | 0, the cache is disabled. Enabled if nonzero. | |
310 | ||
311 | ============================================================== | |
312 | ||
3d43321b KC |
313 | modules_disabled: |
314 | ||
315 | A toggle value indicating if modules are allowed to be loaded | |
316 | in an otherwise modular kernel. This toggle defaults to off | |
317 | (0), but can be set true (1). Once true, modules can be | |
318 | neither loaded nor unloaded, and the toggle cannot be set back | |
319 | to false. | |
320 | ||
321 | ============================================================== | |
322 | ||
807094c0 BP |
323 | nmi_watchdog: |
324 | ||
325 | Enables/Disables the NMI watchdog on x86 systems. When the value is | |
326 | non-zero the NMI watchdog is enabled and will continuously test all | |
327 | online cpus to determine whether or not they are still functioning | |
328 | properly. Currently, passing "nmi_watchdog=" parameter at boot time is | |
329 | required for this function to work. | |
330 | ||
331 | If LAPIC NMI watchdog method is in use (nmi_watchdog=2 kernel | |
332 | parameter), the NMI watchdog shares registers with oprofile. By | |
333 | disabling the NMI watchdog, oprofile may have more registers to | |
334 | utilize. | |
335 | ||
336 | ============================================================== | |
337 | ||
1da177e4 LT |
338 | osrelease, ostype & version: |
339 | ||
340 | # cat osrelease | |
341 | 2.1.88 | |
342 | # cat ostype | |
343 | Linux | |
344 | # cat version | |
345 | #5 Wed Feb 25 21:49:24 MET 1998 | |
346 | ||
347 | The files osrelease and ostype should be clear enough. Version | |
348 | needs a little more clarification however. The '#5' means that | |
349 | this is the fifth kernel built from this source base and the | |
350 | date behind it indicates the time the kernel was built. | |
351 | The only way to tune these values is to rebuild the kernel :-) | |
352 | ||
353 | ============================================================== | |
354 | ||
355 | overflowgid & overflowuid: | |
356 | ||
807094c0 BP |
357 | if your architecture did not always support 32-bit UIDs (i.e. arm, |
358 | i386, m68k, sh, and sparc32), a fixed UID and GID will be returned to | |
359 | applications that use the old 16-bit UID/GID system calls, if the | |
360 | actual UID or GID would exceed 65535. | |
1da177e4 LT |
361 | |
362 | These sysctls allow you to change the value of the fixed UID and GID. | |
363 | The default is 65534. | |
364 | ||
365 | ============================================================== | |
366 | ||
367 | panic: | |
368 | ||
807094c0 BP |
369 | The value in this file represents the number of seconds the kernel |
370 | waits before rebooting on a panic. When you use the software watchdog, | |
371 | the recommended setting is 60. | |
372 | ||
373 | ============================================================== | |
374 | ||
375 | panic_on_unrecovered_nmi: | |
376 | ||
377 | The default Linux behaviour on an NMI of either memory or unknown is | |
378 | to continue operation. For many environments such as scientific | |
379 | computing it is preferable that the box is taken out and the error | |
380 | dealt with than an uncorrected parity/ECC error get propagated. | |
381 | ||
382 | A small number of systems do generate NMI's for bizarre random reasons | |
383 | such as power management so the default is off. That sysctl works like | |
384 | the existing panic controls already in that directory. | |
1da177e4 LT |
385 | |
386 | ============================================================== | |
387 | ||
388 | panic_on_oops: | |
389 | ||
390 | Controls the kernel's behaviour when an oops or BUG is encountered. | |
391 | ||
392 | 0: try to continue operation | |
393 | ||
a982ac06 | 394 | 1: panic immediately. If the `panic' sysctl is also non-zero then the |
8b23d04d | 395 | machine will be rebooted. |
1da177e4 LT |
396 | |
397 | ============================================================== | |
398 | ||
55af7796 MH |
399 | panic_on_stackoverflow: |
400 | ||
401 | Controls the kernel's behavior when detecting the overflows of | |
402 | kernel, IRQ and exception stacks except a user stack. | |
403 | This file shows up if CONFIG_DEBUG_STACKOVERFLOW is enabled. | |
404 | ||
405 | 0: try to continue operation. | |
406 | ||
407 | 1: panic immediately. | |
408 | ||
409 | ============================================================== | |
410 | ||
411 | ||
1da177e4 LT |
412 | pid_max: |
413 | ||
beb7dd86 | 414 | PID allocation wrap value. When the kernel's next PID value |
1da177e4 LT |
415 | reaches this value, it wraps back to a minimum PID value. |
416 | PIDs of value pid_max or larger are not allocated. | |
417 | ||
418 | ============================================================== | |
419 | ||
b8f566b0 PE |
420 | ns_last_pid: |
421 | ||
422 | The last pid allocated in the current (the one task using this sysctl | |
423 | lives in) pid namespace. When selecting a pid for a next task on fork | |
424 | kernel tries to allocate a number starting from this one. | |
425 | ||
426 | ============================================================== | |
427 | ||
1da177e4 LT |
428 | powersave-nap: (PPC only) |
429 | ||
430 | If set, Linux-PPC will use the 'nap' mode of powersaving, | |
431 | otherwise the 'doze' mode will be used. | |
432 | ||
433 | ============================================================== | |
434 | ||
435 | printk: | |
436 | ||
437 | The four values in printk denote: console_loglevel, | |
438 | default_message_loglevel, minimum_console_loglevel and | |
439 | default_console_loglevel respectively. | |
440 | ||
441 | These values influence printk() behavior when printing or | |
442 | logging error messages. See 'man 2 syslog' for more info on | |
443 | the different loglevels. | |
444 | ||
445 | - console_loglevel: messages with a higher priority than | |
446 | this will be printed to the console | |
87889e15 | 447 | - default_message_loglevel: messages without an explicit priority |
1da177e4 LT |
448 | will be printed with this priority |
449 | - minimum_console_loglevel: minimum (highest) value to which | |
450 | console_loglevel can be set | |
451 | - default_console_loglevel: default value for console_loglevel | |
452 | ||
453 | ============================================================== | |
454 | ||
807094c0 BP |
455 | printk_delay: |
456 | ||
457 | Delay each printk message in printk_delay milliseconds | |
458 | ||
459 | Value from 0 - 10000 is allowed. | |
460 | ||
461 | ============================================================== | |
462 | ||
1da177e4 LT |
463 | printk_ratelimit: |
464 | ||
465 | Some warning messages are rate limited. printk_ratelimit specifies | |
466 | the minimum length of time between these messages (in jiffies), by | |
467 | default we allow one every 5 seconds. | |
468 | ||
469 | A value of 0 will disable rate limiting. | |
470 | ||
471 | ============================================================== | |
472 | ||
473 | printk_ratelimit_burst: | |
474 | ||
475 | While long term we enforce one message per printk_ratelimit | |
476 | seconds, we do allow a burst of messages to pass through. | |
477 | printk_ratelimit_burst specifies the number of messages we can | |
478 | send before ratelimiting kicks in. | |
479 | ||
480 | ============================================================== | |
481 | ||
807094c0 | 482 | randomize_va_space: |
1ec7fd50 JK |
483 | |
484 | This option can be used to select the type of process address | |
485 | space randomization that is used in the system, for architectures | |
486 | that support this feature. | |
487 | ||
b7f5ab6f HS |
488 | 0 - Turn the process address space randomization off. This is the |
489 | default for architectures that do not support this feature anyways, | |
490 | and kernels that are booted with the "norandmaps" parameter. | |
1ec7fd50 JK |
491 | |
492 | 1 - Make the addresses of mmap base, stack and VDSO page randomized. | |
493 | This, among other things, implies that shared libraries will be | |
b7f5ab6f HS |
494 | loaded to random addresses. Also for PIE-linked binaries, the |
495 | location of code start is randomized. This is the default if the | |
496 | CONFIG_COMPAT_BRK option is enabled. | |
1ec7fd50 | 497 | |
b7f5ab6f HS |
498 | 2 - Additionally enable heap randomization. This is the default if |
499 | CONFIG_COMPAT_BRK is disabled. | |
500 | ||
501 | There are a few legacy applications out there (such as some ancient | |
1ec7fd50 | 502 | versions of libc.so.5 from 1996) that assume that brk area starts |
b7f5ab6f HS |
503 | just after the end of the code+bss. These applications break when |
504 | start of the brk area is randomized. There are however no known | |
1ec7fd50 | 505 | non-legacy applications that would be broken this way, so for most |
b7f5ab6f HS |
506 | systems it is safe to choose full randomization. |
507 | ||
508 | Systems with ancient and/or broken binaries should be configured | |
509 | with CONFIG_COMPAT_BRK enabled, which excludes the heap from process | |
510 | address space randomization. | |
1ec7fd50 JK |
511 | |
512 | ============================================================== | |
513 | ||
1da177e4 LT |
514 | reboot-cmd: (Sparc only) |
515 | ||
516 | ??? This seems to be a way to give an argument to the Sparc | |
517 | ROM/Flash boot loader. Maybe to tell it what to do after | |
518 | rebooting. ??? | |
519 | ||
520 | ============================================================== | |
521 | ||
522 | rtsig-max & rtsig-nr: | |
523 | ||
524 | The file rtsig-max can be used to tune the maximum number | |
525 | of POSIX realtime (queued) signals that can be outstanding | |
526 | in the system. | |
527 | ||
528 | rtsig-nr shows the number of RT signals currently queued. | |
529 | ||
530 | ============================================================== | |
531 | ||
532 | sg-big-buff: | |
533 | ||
534 | This file shows the size of the generic SCSI (sg) buffer. | |
535 | You can't tune it just yet, but you could change it on | |
536 | compile time by editing include/scsi/sg.h and changing | |
537 | the value of SG_BIG_BUFF. | |
538 | ||
539 | There shouldn't be any reason to change this value. If | |
540 | you can come up with one, you probably know what you | |
541 | are doing anyway :) | |
542 | ||
543 | ============================================================== | |
544 | ||
807094c0 | 545 | shmmax: |
1da177e4 LT |
546 | |
547 | This value can be used to query and set the run time limit | |
548 | on the maximum shared memory segment size that can be created. | |
807094c0 | 549 | Shared memory segments up to 1Gb are now supported in the |
1da177e4 LT |
550 | kernel. This value defaults to SHMMAX. |
551 | ||
552 | ============================================================== | |
553 | ||
b34a6b1d VK |
554 | shm_rmid_forced: |
555 | ||
556 | Linux lets you set resource limits, including how much memory one | |
557 | process can consume, via setrlimit(2). Unfortunately, shared memory | |
558 | segments are allowed to exist without association with any process, and | |
559 | thus might not be counted against any resource limits. If enabled, | |
560 | shared memory segments are automatically destroyed when their attach | |
561 | count becomes zero after a detach or a process termination. It will | |
562 | also destroy segments that were created, but never attached to, on exit | |
563 | from the process. The only use left for IPC_RMID is to immediately | |
564 | destroy an unattached segment. Of course, this breaks the way things are | |
565 | defined, so some applications might stop working. Note that this | |
566 | feature will do you no good unless you also configure your resource | |
567 | limits (in particular, RLIMIT_AS and RLIMIT_NPROC). Most systems don't | |
568 | need this. | |
569 | ||
570 | Note that if you change this from 0 to 1, already created segments | |
571 | without users and with a dead originative process will be destroyed. | |
572 | ||
573 | ============================================================== | |
574 | ||
c4f3b63f RT |
575 | softlockup_thresh: |
576 | ||
b4d19cc8 AM |
577 | This value can be used to lower the softlockup tolerance threshold. The |
578 | default threshold is 60 seconds. If a cpu is locked up for 60 seconds, | |
579 | the kernel complains. Valid values are 1-60 seconds. Setting this | |
580 | tunable to zero will disable the softlockup detection altogether. | |
c4f3b63f RT |
581 | |
582 | ============================================================== | |
583 | ||
807094c0 | 584 | tainted: |
1da177e4 LT |
585 | |
586 | Non-zero if the kernel has been tainted. Numeric values, which | |
587 | can be ORed together: | |
588 | ||
bb20698d GKH |
589 | 1 - A module with a non-GPL license has been loaded, this |
590 | includes modules with no license. | |
591 | Set by modutils >= 2.4.9 and module-init-tools. | |
592 | 2 - A module was force loaded by insmod -f. | |
593 | Set by modutils >= 2.4.9 and module-init-tools. | |
594 | 4 - Unsafe SMP processors: SMP with CPUs not designed for SMP. | |
595 | 8 - A module was forcibly unloaded from the system by rmmod -f. | |
596 | 16 - A hardware machine check error occurred on the system. | |
597 | 32 - A bad page was discovered on the system. | |
598 | 64 - The user has asked that the system be marked "tainted". This | |
599 | could be because they are running software that directly modifies | |
600 | the hardware, or for other reasons. | |
601 | 128 - The system has died. | |
602 | 256 - The ACPI DSDT has been overridden with one supplied by the user | |
603 | instead of using the one provided by the hardware. | |
604 | 512 - A kernel warning has occurred. | |
605 | 1024 - A module from drivers/staging was loaded. | |
f5fe184b LF |
606 | 2048 - The system is working around a severe firmware bug. |
607 | 4096 - An out-of-tree module has been loaded. | |
1da177e4 | 608 | |
760df93e SF |
609 | ============================================================== |
610 | ||
760df93e SF |
611 | unknown_nmi_panic: |
612 | ||
807094c0 BP |
613 | The value in this file affects behavior of handling NMI. When the |
614 | value is non-zero, unknown NMI is trapped and then panic occurs. At | |
615 | that time, kernel debugging information is displayed on console. | |
760df93e | 616 | |
807094c0 BP |
617 | NMI switch that most IA32 servers have fires unknown NMI up, for |
618 | example. If a system hangs up, try pressing the NMI switch. |