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1da177e4
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1
2config PRINTK_TIME
3 bool "Show timing information on printks"
d3b8b6e5 4 depends on PRINTK
1da177e4 5 help
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6 Selecting this option causes time stamps of the printk()
7 messages to be added to the output of the syslog() system
8 call and at the console.
9
10 The timestamp is always recorded internally, and exported
11 to /dev/kmsg. This flag just specifies if the timestamp should
12 be included, not that the timestamp is recorded.
13
14 The behavior is also controlled by the kernel command line
15 parameter printk.time=1. See Documentation/kernel-parameters.txt
1da177e4 16
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17config DEFAULT_MESSAGE_LOGLEVEL
18 int "Default message log level (1-7)"
19 range 1 7
20 default "4"
21 help
22 Default log level for printk statements with no specified priority.
23
24 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
25 that are auditing their logs closely may want to set it to a lower
26 priority.
27
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28config ENABLE_WARN_DEPRECATED
29 bool "Enable __deprecated logic"
30 default y
31 help
32 Enable the __deprecated logic in the kernel build.
33 Disable this to suppress the "warning: 'foo' is deprecated
34 (declared at kernel/power/somefile.c:1234)" messages.
35
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36config ENABLE_MUST_CHECK
37 bool "Enable __must_check logic"
38 default y
39 help
40 Enable the __must_check logic in the kernel build. Disable this to
41 suppress the "warning: ignoring return value of 'foo', declared with
42 attribute warn_unused_result" messages.
1da177e4 43
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44config FRAME_WARN
45 int "Warn for stack frames larger than (needs gcc 4.4)"
46 range 0 8192
47 default 1024 if !64BIT
48 default 2048 if 64BIT
49 help
50 Tell gcc to warn at build time for stack frames larger than this.
51 Setting this too low will cause a lot of warnings.
52 Setting it to 0 disables the warning.
53 Requires gcc 4.4
54
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55config MAGIC_SYSRQ
56 bool "Magic SysRq key"
f346f4b3 57 depends on !UML
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58 help
59 If you say Y here, you will have some control over the system even
60 if the system crashes for example during kernel debugging (e.g., you
61 will be able to flush the buffer cache to disk, reboot the system
62 immediately or dump some status information). This is accomplished
63 by pressing various keys while holding SysRq (Alt+PrintScreen). It
64 also works on a serial console (on PC hardware at least), if you
65 send a BREAK and then within 5 seconds a command keypress. The
66 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
67 unless you really know what this hack does.
68
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69config STRIP_ASM_SYMS
70 bool "Strip assembler-generated symbols during link"
71 default n
72 help
73 Strip internal assembler-generated symbols during a link (symbols
74 that look like '.Lxxx') so they don't pollute the output of
75 get_wchan() and suchlike.
76
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77config READABLE_ASM
78 bool "Generate readable assembler code"
79 depends on DEBUG_KERNEL
80 help
81 Disable some compiler optimizations that tend to generate human unreadable
82 assembler output. This may make the kernel slightly slower, but it helps
83 to keep kernel developers who have to stare a lot at assembler listings
84 sane.
85
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86config UNUSED_SYMBOLS
87 bool "Enable unused/obsolete exported symbols"
88 default y if X86
89 help
90 Unused but exported symbols make the kernel needlessly bigger. For
91 that reason most of these unused exports will soon be removed. This
92 option is provided temporarily to provide a transition period in case
93 some external kernel module needs one of these symbols anyway. If you
94 encounter such a case in your module, consider if you are actually
95 using the right API. (rationale: since nobody in the kernel is using
96 this in a module, there is a pretty good chance it's actually the
97 wrong interface to use). If you really need the symbol, please send a
98 mail to the linux kernel mailing list mentioning the symbol and why
99 you really need it, and what the merge plan to the mainline kernel for
100 your module is.
101
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102config DEBUG_FS
103 bool "Debug Filesystem"
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104 help
105 debugfs is a virtual file system that kernel developers use to put
106 debugging files into. Enable this option to be able to read and
107 write to these files.
108
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109 For detailed documentation on the debugfs API, see
110 Documentation/DocBook/filesystems.
111
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112 If unsure, say N.
113
114config HEADERS_CHECK
115 bool "Run 'make headers_check' when building vmlinux"
116 depends on !UML
117 help
118 This option will extract the user-visible kernel headers whenever
119 building the kernel, and will run basic sanity checks on them to
120 ensure that exported files do not attempt to include files which
121 were not exported, etc.
122
123 If you're making modifications to header files which are
124 relevant for userspace, say 'Y', and check the headers
125 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
126 your build tree), to make sure they're suitable.
127
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128config DEBUG_SECTION_MISMATCH
129 bool "Enable full Section mismatch analysis"
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130 help
131 The section mismatch analysis checks if there are illegal
132 references from one section to another section.
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133 During linktime or runtime, some sections are dropped;
134 any use of code/data previously in these sections would
91341d4b 135 most likely result in an oops.
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136 In the code, functions and variables are annotated with
137 __init, __devinit, etc. (see the full list in include/linux/init.h),
d6fbfa4f 138 which results in the code/data being placed in specific sections.
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139 The section mismatch analysis is always performed after a full
140 kernel build, and enabling this option causes the following
141 additional steps to occur:
142 - Add the option -fno-inline-functions-called-once to gcc commands.
143 When inlining a function annotated with __init in a non-init
144 function, we would lose the section information and thus
91341d4b 145 the analysis would not catch the illegal reference.
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146 This option tells gcc to inline less (but it does result in
147 a larger kernel).
148 - Run the section mismatch analysis for each module/built-in.o file.
149 When we run the section mismatch analysis on vmlinux.o, we
d6fbfa4f 150 lose valueble information about where the mismatch was
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151 introduced.
152 Running the analysis for each module/built-in.o file
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153 tells where the mismatch happens much closer to the
154 source. The drawback is that the same mismatch is
155 reported at least twice.
156 - Enable verbose reporting from modpost in order to help resolve
157 the section mismatches that are reported.
91341d4b 158
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159config DEBUG_KERNEL
160 bool "Kernel debugging"
161 help
162 Say Y here if you are developing drivers or trying to debug and
163 identify kernel problems.
164
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165config DEBUG_SHIRQ
166 bool "Debug shared IRQ handlers"
167 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
168 help
169 Enable this to generate a spurious interrupt as soon as a shared
170 interrupt handler is registered, and just before one is deregistered.
171 Drivers ought to be able to handle interrupts coming in at those
172 points; some don't and need to be caught.
173
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174config LOCKUP_DETECTOR
175 bool "Detect Hard and Soft Lockups"
dea20a3f 176 depends on DEBUG_KERNEL && !S390
8446f1d3 177 help
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178 Say Y here to enable the kernel to act as a watchdog to detect
179 hard and soft lockups.
180
181 Softlockups are bugs that cause the kernel to loop in kernel
5f329089 182 mode for more than 20 seconds, without giving other tasks a
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183 chance to run. The current stack trace is displayed upon
184 detection and the system will stay locked up.
8446f1d3 185
58687acb 186 Hardlockups are bugs that cause the CPU to loop in kernel mode
5f329089 187 for more than 10 seconds, without letting other interrupts have a
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188 chance to run. The current stack trace is displayed upon detection
189 and the system will stay locked up.
8446f1d3 190
58687acb 191 The overhead should be minimal. A periodic hrtimer runs to
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192 generate interrupts and kick the watchdog task every 4 seconds.
193 An NMI is generated every 10 seconds or so to check for hardlockups.
194
195 The frequency of hrtimer and NMI events and the soft and hard lockup
196 thresholds can be controlled through the sysctl watchdog_thresh.
8446f1d3 197
23637d47 198config HARDLOCKUP_DETECTOR
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199 def_bool y
200 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
201 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
8446f1d3 202
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203config BOOTPARAM_HARDLOCKUP_PANIC
204 bool "Panic (Reboot) On Hard Lockups"
8f1f66ed 205 depends on HARDLOCKUP_DETECTOR
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206 help
207 Say Y here to enable the kernel to panic on "hard lockups",
208 which are bugs that cause the kernel to loop in kernel
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209 mode with interrupts disabled for more than 10 seconds (configurable
210 using the watchdog_thresh sysctl).
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211
212 Say N if unsure.
213
214config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
215 int
8f1f66ed 216 depends on HARDLOCKUP_DETECTOR
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217 range 0 1
218 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
219 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
220
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221config BOOTPARAM_SOFTLOCKUP_PANIC
222 bool "Panic (Reboot) On Soft Lockups"
89d7ce2a 223 depends on LOCKUP_DETECTOR
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224 help
225 Say Y here to enable the kernel to panic on "soft lockups",
226 which are bugs that cause the kernel to loop in kernel
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227 mode for more than 20 seconds (configurable using the watchdog_thresh
228 sysctl), without giving other tasks a chance to run.
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229
230 The panic can be used in combination with panic_timeout,
231 to cause the system to reboot automatically after a
232 lockup has been detected. This feature is useful for
233 high-availability systems that have uptime guarantees and
234 where a lockup must be resolved ASAP.
235
236 Say N if unsure.
237
238config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
239 int
e16bb1d7 240 depends on LOCKUP_DETECTOR
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241 range 0 1
242 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
243 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
244
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245config PANIC_ON_OOPS
246 bool "Panic on Oops" if EXPERT
247 default n
248 help
249 Say Y here to enable the kernel to panic when it oopses. This
250 has the same effect as setting oops=panic on the kernel command
251 line.
252
253 This feature is useful to ensure that the kernel does not do
254 anything erroneous after an oops which could result in data
255 corruption or other issues.
256
257 Say N if unsure.
258
259config PANIC_ON_OOPS_VALUE
260 int
261 range 0 1
262 default 0 if !PANIC_ON_OOPS
263 default 1 if PANIC_ON_OOPS
264
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265config DETECT_HUNG_TASK
266 bool "Detect Hung Tasks"
267 depends on DEBUG_KERNEL
8edbb83e 268 default LOCKUP_DETECTOR
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269 help
270 Say Y here to enable the kernel to detect "hung tasks",
271 which are bugs that cause the task to be stuck in
272 uninterruptible "D" state indefinitiley.
273
274 When a hung task is detected, the kernel will print the
275 current stack trace (which you should report), but the
276 task will stay in uninterruptible state. If lockdep is
277 enabled then all held locks will also be reported. This
278 feature has negligible overhead.
279
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280config DEFAULT_HUNG_TASK_TIMEOUT
281 int "Default timeout for hung task detection (in seconds)"
282 depends on DETECT_HUNG_TASK
283 default 120
284 help
285 This option controls the default timeout (in seconds) used
286 to determine when a task has become non-responsive and should
287 be considered hung.
288
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289 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
290 sysctl or by writing a value to
291 /proc/sys/kernel/hung_task_timeout_secs.
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292
293 A timeout of 0 disables the check. The default is two minutes.
294 Keeping the default should be fine in most cases.
295
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296config BOOTPARAM_HUNG_TASK_PANIC
297 bool "Panic (Reboot) On Hung Tasks"
298 depends on DETECT_HUNG_TASK
299 help
300 Say Y here to enable the kernel to panic on "hung tasks",
301 which are bugs that cause the kernel to leave a task stuck
302 in uninterruptible "D" state.
303
304 The panic can be used in combination with panic_timeout,
305 to cause the system to reboot automatically after a
306 hung task has been detected. This feature is useful for
307 high-availability systems that have uptime guarantees and
308 where a hung tasks must be resolved ASAP.
309
310 Say N if unsure.
311
312config BOOTPARAM_HUNG_TASK_PANIC_VALUE
313 int
314 depends on DETECT_HUNG_TASK
315 range 0 1
316 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
317 default 1 if BOOTPARAM_HUNG_TASK_PANIC
318
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319config SCHED_DEBUG
320 bool "Collect scheduler debugging info"
321 depends on DEBUG_KERNEL && PROC_FS
322 default y
323 help
324 If you say Y here, the /proc/sched_debug file will be provided
325 that can help debug the scheduler. The runtime overhead of this
326 option is minimal.
327
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328config SCHEDSTATS
329 bool "Collect scheduler statistics"
330 depends on DEBUG_KERNEL && PROC_FS
331 help
332 If you say Y here, additional code will be inserted into the
333 scheduler and related routines to collect statistics about
334 scheduler behavior and provide them in /proc/schedstat. These
335 stats may be useful for both tuning and debugging the scheduler
336 If you aren't debugging the scheduler or trying to tune a specific
337 application, you can say N to avoid the very slight overhead
338 this adds.
339
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340config TIMER_STATS
341 bool "Collect kernel timers statistics"
342 depends on DEBUG_KERNEL && PROC_FS
343 help
344 If you say Y here, additional code will be inserted into the
345 timer routines to collect statistics about kernel timers being
346 reprogrammed. The statistics can be read from /proc/timer_stats.
347 The statistics collection is started by writing 1 to /proc/timer_stats,
348 writing 0 stops it. This feature is useful to collect information
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349 about timer usage patterns in kernel and userspace. This feature
350 is lightweight if enabled in the kernel config but not activated
351 (it defaults to deactivated on bootup and will only be activated
352 if some application like powertop activates it explicitly).
82f67cd9 353
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354config DEBUG_OBJECTS
355 bool "Debug object operations"
356 depends on DEBUG_KERNEL
357 help
358 If you say Y here, additional code will be inserted into the
359 kernel to track the life time of various objects and validate
360 the operations on those objects.
361
362config DEBUG_OBJECTS_SELFTEST
363 bool "Debug objects selftest"
364 depends on DEBUG_OBJECTS
365 help
366 This enables the selftest of the object debug code.
367
368config DEBUG_OBJECTS_FREE
369 bool "Debug objects in freed memory"
370 depends on DEBUG_OBJECTS
371 help
372 This enables checks whether a k/v free operation frees an area
373 which contains an object which has not been deactivated
374 properly. This can make kmalloc/kfree-intensive workloads
375 much slower.
376
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377config DEBUG_OBJECTS_TIMERS
378 bool "Debug timer objects"
379 depends on DEBUG_OBJECTS
380 help
381 If you say Y here, additional code will be inserted into the
382 timer routines to track the life time of timer objects and
383 validate the timer operations.
384
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385config DEBUG_OBJECTS_WORK
386 bool "Debug work objects"
387 depends on DEBUG_OBJECTS
388 help
389 If you say Y here, additional code will be inserted into the
390 work queue routines to track the life time of work objects and
391 validate the work operations.
392
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393config DEBUG_OBJECTS_RCU_HEAD
394 bool "Debug RCU callbacks objects"
fc2ecf7e 395 depends on DEBUG_OBJECTS
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396 help
397 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
398
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399config DEBUG_OBJECTS_PERCPU_COUNTER
400 bool "Debug percpu counter objects"
401 depends on DEBUG_OBJECTS
402 help
403 If you say Y here, additional code will be inserted into the
404 percpu counter routines to track the life time of percpu counter
405 objects and validate the percpu counter operations.
406
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407config DEBUG_OBJECTS_ENABLE_DEFAULT
408 int "debug_objects bootup default value (0-1)"
409 range 0 1
410 default "1"
411 depends on DEBUG_OBJECTS
412 help
413 Debug objects boot parameter default value
414
1da177e4 415config DEBUG_SLAB
4a2f0acf 416 bool "Debug slab memory allocations"
7d46d9e6 417 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
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418 help
419 Say Y here to have the kernel do limited verification on memory
420 allocation as well as poisoning memory on free to catch use of freed
421 memory. This can make kmalloc/kfree-intensive workloads much slower.
422
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423config DEBUG_SLAB_LEAK
424 bool "Memory leak debugging"
425 depends on DEBUG_SLAB
426
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427config SLUB_DEBUG_ON
428 bool "SLUB debugging on by default"
7d46d9e6 429 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
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430 default n
431 help
432 Boot with debugging on by default. SLUB boots by default with
433 the runtime debug capabilities switched off. Enabling this is
434 equivalent to specifying the "slub_debug" parameter on boot.
435 There is no support for more fine grained debug control like
436 possible with slub_debug=xxx. SLUB debugging may be switched
437 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
438 "slub_debug=-".
439
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440config SLUB_STATS
441 default n
442 bool "Enable SLUB performance statistics"
ab4d5ed5 443 depends on SLUB && SYSFS
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444 help
445 SLUB statistics are useful to debug SLUBs allocation behavior in
446 order find ways to optimize the allocator. This should never be
447 enabled for production use since keeping statistics slows down
448 the allocator by a few percentage points. The slabinfo command
449 supports the determination of the most active slabs to figure
450 out which slabs are relevant to a particular load.
451 Try running: slabinfo -DA
452
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453config HAVE_DEBUG_KMEMLEAK
454 bool
455
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456config DEBUG_KMEMLEAK
457 bool "Kernel memory leak detector"
b69ec42b 458 depends on DEBUG_KERNEL && EXPERIMENTAL && HAVE_DEBUG_KMEMLEAK
79e0d9bd 459 select DEBUG_FS
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460 select STACKTRACE if STACKTRACE_SUPPORT
461 select KALLSYMS
b60e26a2 462 select CRC32
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463 help
464 Say Y here if you want to enable the memory leak
465 detector. The memory allocation/freeing is traced in a way
466 similar to the Boehm's conservative garbage collector, the
467 difference being that the orphan objects are not freed but
468 only shown in /sys/kernel/debug/kmemleak. Enabling this
469 feature will introduce an overhead to memory
470 allocations. See Documentation/kmemleak.txt for more
471 details.
472
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473 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
474 of finding leaks due to the slab objects poisoning.
475
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476 In order to access the kmemleak file, debugfs needs to be
477 mounted (usually at /sys/kernel/debug).
478
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479config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
480 int "Maximum kmemleak early log entries"
481 depends on DEBUG_KMEMLEAK
dfcc3e6a 482 range 200 40000
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483 default 400
484 help
485 Kmemleak must track all the memory allocations to avoid
486 reporting false positives. Since memory may be allocated or
487 freed before kmemleak is initialised, an early log buffer is
488 used to store these actions. If kmemleak reports "early log
489 buffer exceeded", please increase this value.
490
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491config DEBUG_KMEMLEAK_TEST
492 tristate "Simple test for the kernel memory leak detector"
9718269a 493 depends on DEBUG_KMEMLEAK && m
0822ee4a 494 help
9718269a 495 This option enables a module that explicitly leaks memory.
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496
497 If unsure, say N.
498
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499config DEBUG_KMEMLEAK_DEFAULT_OFF
500 bool "Default kmemleak to off"
501 depends on DEBUG_KMEMLEAK
502 help
503 Say Y here to disable kmemleak by default. It can then be enabled
504 on the command line via kmemleak=on.
505
1da177e4
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506config DEBUG_PREEMPT
507 bool "Debug preemptible kernel"
01deab98 508 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
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509 default y
510 help
511 If you say Y here then the kernel will use a debug variant of the
512 commonly used smp_processor_id() function and will print warnings
513 if kernel code uses it in a preemption-unsafe way. Also, the kernel
514 will detect preemption count underflows.
515
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516config DEBUG_RT_MUTEXES
517 bool "RT Mutex debugging, deadlock detection"
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518 depends on DEBUG_KERNEL && RT_MUTEXES
519 help
520 This allows rt mutex semantics violations and rt mutex related
521 deadlocks (lockups) to be detected and reported automatically.
522
523config DEBUG_PI_LIST
524 bool
525 default y
526 depends on DEBUG_RT_MUTEXES
527
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528config RT_MUTEX_TESTER
529 bool "Built-in scriptable tester for rt-mutexes"
a1583d3e 530 depends on DEBUG_KERNEL && RT_MUTEXES
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531 help
532 This option enables a rt-mutex tester.
533
1da177e4 534config DEBUG_SPINLOCK
4d9f34ad 535 bool "Spinlock and rw-lock debugging: basic checks"
1da177e4 536 depends on DEBUG_KERNEL
e335e3eb 537 select UNINLINE_SPIN_UNLOCK
1da177e4
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538 help
539 Say Y here and build SMP to catch missing spinlock initialization
540 and certain other kinds of spinlock errors commonly made. This is
541 best used in conjunction with the NMI watchdog so that spinlock
542 deadlocks are also debuggable.
543
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544config DEBUG_MUTEXES
545 bool "Mutex debugging: basic checks"
546 depends on DEBUG_KERNEL
547 help
548 This feature allows mutex semantics violations to be detected and
549 reported.
550
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551config DEBUG_LOCK_ALLOC
552 bool "Lock debugging: detect incorrect freeing of live locks"
517e7aa5 553 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
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554 select DEBUG_SPINLOCK
555 select DEBUG_MUTEXES
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556 select LOCKDEP
557 help
558 This feature will check whether any held lock (spinlock, rwlock,
559 mutex or rwsem) is incorrectly freed by the kernel, via any of the
560 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
561 vfree(), etc.), whether a live lock is incorrectly reinitialized via
562 spin_lock_init()/mutex_init()/etc., or whether there is any lock
563 held during task exit.
564
565config PROVE_LOCKING
566 bool "Lock debugging: prove locking correctness"
517e7aa5 567 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
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568 select LOCKDEP
569 select DEBUG_SPINLOCK
570 select DEBUG_MUTEXES
4d9f34ad 571 select DEBUG_LOCK_ALLOC
46b93b74 572 select TRACE_IRQFLAGS
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573 default n
574 help
575 This feature enables the kernel to prove that all locking
576 that occurs in the kernel runtime is mathematically
577 correct: that under no circumstance could an arbitrary (and
578 not yet triggered) combination of observed locking
579 sequences (on an arbitrary number of CPUs, running an
580 arbitrary number of tasks and interrupt contexts) cause a
581 deadlock.
582
583 In short, this feature enables the kernel to report locking
584 related deadlocks before they actually occur.
585
586 The proof does not depend on how hard and complex a
587 deadlock scenario would be to trigger: how many
588 participant CPUs, tasks and irq-contexts would be needed
589 for it to trigger. The proof also does not depend on
590 timing: if a race and a resulting deadlock is possible
591 theoretically (no matter how unlikely the race scenario
592 is), it will be proven so and will immediately be
593 reported by the kernel (once the event is observed that
594 makes the deadlock theoretically possible).
595
596 If a deadlock is impossible (i.e. the locking rules, as
597 observed by the kernel, are mathematically correct), the
598 kernel reports nothing.
599
600 NOTE: this feature can also be enabled for rwlocks, mutexes
601 and rwsems - in which case all dependencies between these
602 different locking variants are observed and mapped too, and
603 the proof of observed correctness is also maintained for an
604 arbitrary combination of these separate locking variants.
605
606 For more details, see Documentation/lockdep-design.txt.
607
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608config PROVE_RCU
609 bool "RCU debugging: prove RCU correctness"
610 depends on PROVE_LOCKING
611 default n
612 help
613 This feature enables lockdep extensions that check for correct
614 use of RCU APIs. This is currently under development. Say Y
615 if you want to debug RCU usage or help work on the PROVE_RCU
616 feature.
617
618 Say N if you are unsure.
619
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620config PROVE_RCU_REPEATEDLY
621 bool "RCU debugging: don't disable PROVE_RCU on first splat"
622 depends on PROVE_RCU
623 default n
624 help
625 By itself, PROVE_RCU will disable checking upon issuing the
626 first warning (or "splat"). This feature prevents such
627 disabling, allowing multiple RCU-lockdep warnings to be printed
628 on a single reboot.
629
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630 Say Y to allow multiple RCU-lockdep warnings per boot.
631
632 Say N if you are unsure.
633
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634config PROVE_RCU_DELAY
635 bool "RCU debugging: preemptible RCU race provocation"
636 depends on DEBUG_KERNEL && PREEMPT_RCU
637 default n
638 help
639 There is a class of races that involve an unlikely preemption
640 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
641 been set to INT_MIN. This feature inserts a delay at that
642 point to increase the probability of these races.
643
644 Say Y to increase probability of preemption of __rcu_read_unlock().
645
646 Say N if you are unsure.
647
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648config SPARSE_RCU_POINTER
649 bool "RCU debugging: sparse-based checks for pointer usage"
650 default n
651 help
652 This feature enables the __rcu sparse annotation for
653 RCU-protected pointers. This annotation will cause sparse
654 to flag any non-RCU used of annotated pointers. This can be
655 helpful when debugging RCU usage. Please note that this feature
656 is not intended to enforce code cleanliness; it is instead merely
657 a debugging aid.
658
659 Say Y to make sparse flag questionable use of RCU-protected pointers
660
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661 Say N if you are unsure.
662
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663config LOCKDEP
664 bool
517e7aa5 665 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad 666 select STACKTRACE
79aac889 667 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
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668 select KALLSYMS
669 select KALLSYMS_ALL
670
f20786ff 671config LOCK_STAT
fdfb870f 672 bool "Lock usage statistics"
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673 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
674 select LOCKDEP
675 select DEBUG_SPINLOCK
676 select DEBUG_MUTEXES
677 select DEBUG_LOCK_ALLOC
678 default n
679 help
680 This feature enables tracking lock contention points
681
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682 For more details, see Documentation/lockstat.txt
683
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684 This also enables lock events required by "perf lock",
685 subcommand of perf.
686 If you want to use "perf lock", you also need to turn on
687 CONFIG_EVENT_TRACING.
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688
689 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
dd8b1cf6 690 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
84c6f88f 691
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692config DEBUG_LOCKDEP
693 bool "Lock dependency engine debugging"
517e7aa5 694 depends on DEBUG_KERNEL && LOCKDEP
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695 help
696 If you say Y here, the lock dependency engine will do
697 additional runtime checks to debug itself, at the price
698 of more runtime overhead.
699
700config TRACE_IRQFLAGS
701 bool
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702 help
703 Enables hooks to interrupt enabling and disabling for
704 either tracing or lock debugging.
4d9f34ad 705
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706config DEBUG_ATOMIC_SLEEP
707 bool "Sleep inside atomic section checking"
e8f7c70f 708 select PREEMPT_COUNT
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709 depends on DEBUG_KERNEL
710 help
711 If you say Y here, various routines which may sleep will become very
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712 noisy if they are called inside atomic sections: when a spinlock is
713 held, inside an rcu read side critical section, inside preempt disabled
714 sections, inside an interrupt, etc...
1da177e4 715
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716config DEBUG_LOCKING_API_SELFTESTS
717 bool "Locking API boot-time self-tests"
718 depends on DEBUG_KERNEL
719 help
720 Say Y here if you want the kernel to run a short self-test during
721 bootup. The self-test checks whether common types of locking bugs
722 are detected by debugging mechanisms or not. (if you disable
723 lock debugging then those bugs wont be detected of course.)
724 The following locking APIs are covered: spinlocks, rwlocks,
725 mutexes and rwsems.
726
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727config STACKTRACE
728 bool
729 depends on STACKTRACE_SUPPORT
730
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731config DEBUG_STACK_USAGE
732 bool "Stack utilization instrumentation"
e9c31b32 733 depends on DEBUG_KERNEL && !IA64 && !PARISC
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734 help
735 Enables the display of the minimum amount of free stack which each
736 task has ever had available in the sysrq-T and sysrq-P debug output.
737
738 This option will slow down process creation somewhat.
739
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740config DEBUG_KOBJECT
741 bool "kobject debugging"
742 depends on DEBUG_KERNEL
743 help
744 If you say Y here, some extra kobject debugging messages will be sent
745 to the syslog.
746
747config DEBUG_HIGHMEM
748 bool "Highmem debugging"
749 depends on DEBUG_KERNEL && HIGHMEM
750 help
751 This options enables addition error checking for high memory systems.
752 Disable for production systems.
753
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754config HAVE_DEBUG_BUGVERBOSE
755 bool
756
1da177e4 757config DEBUG_BUGVERBOSE
6a108a14 758 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
9b2a60c4 759 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
8420e7ef 760 default y
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761 help
762 Say Y here to make BUG() panics output the file name and line number
763 of the BUG call as well as the EIP and oops trace. This aids
764 debugging but costs about 70-100K of memory.
765
766config DEBUG_INFO
767 bool "Compile the kernel with debug info"
768 depends on DEBUG_KERNEL
769 help
770 If you say Y here the resulting kernel image will include
771 debugging info resulting in a larger kernel image.
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772 This adds debug symbols to the kernel and modules (gcc -g), and
773 is needed if you intend to use kernel crashdump or binary object
774 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
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775 Say Y here only if you plan to debug the kernel.
776
777 If unsure, say N.
778
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779config DEBUG_INFO_REDUCED
780 bool "Reduce debugging information"
781 depends on DEBUG_INFO
782 help
783 If you say Y here gcc is instructed to generate less debugging
784 information for structure types. This means that tools that
785 need full debugging information (like kgdb or systemtap) won't
786 be happy. But if you merely need debugging information to
787 resolve line numbers there is no loss. Advantage is that
788 build directory object sizes shrink dramatically over a full
789 DEBUG_INFO build and compile times are reduced too.
790 Only works with newer gcc versions.
791
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792config DEBUG_VM
793 bool "Debug VM"
794 depends on DEBUG_KERNEL
795 help
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796 Enable this to turn on extended checks in the virtual-memory system
797 that may impact performance.
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798
799 If unsure, say N.
800
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801config DEBUG_VM_RB
802 bool "Debug VM red-black trees"
803 depends on DEBUG_VM
804 help
805 Enable this to turn on more extended checks in the virtual-memory
806 system that may impact performance.
807
808 If unsure, say N.
809
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810config DEBUG_VIRTUAL
811 bool "Debug VM translations"
812 depends on DEBUG_KERNEL && X86
813 help
814 Enable some costly sanity checks in virtual to page code. This can
815 catch mistakes with virt_to_page() and friends.
816
817 If unsure, say N.
818
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819config DEBUG_NOMMU_REGIONS
820 bool "Debug the global anon/private NOMMU mapping region tree"
821 depends on DEBUG_KERNEL && !MMU
822 help
823 This option causes the global tree of anonymous and private mapping
824 regions to be regularly checked for invalid topology.
825
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826config DEBUG_WRITECOUNT
827 bool "Debug filesystem writers count"
828 depends on DEBUG_KERNEL
829 help
830 Enable this to catch wrong use of the writers count in struct
831 vfsmount. This will increase the size of each file struct by
832 32 bits.
833
834 If unsure, say N.
835
6b74ab97 836config DEBUG_MEMORY_INIT
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837 bool "Debug memory initialisation" if EXPERT
838 default !EXPERT
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839 help
840 Enable this for additional checks during memory initialisation.
841 The sanity checks verify aspects of the VM such as the memory model
842 and other information provided by the architecture. Verbose
843 information will be printed at KERN_DEBUG loglevel depending
844 on the mminit_loglevel= command-line option.
845
846 If unsure, say Y
847
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848config DEBUG_LIST
849 bool "Debug linked list manipulation"
850 depends on DEBUG_KERNEL
851 help
852 Enable this to turn on extended checks in the linked-list
853 walking routines.
854
855 If unsure, say N.
856
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857config TEST_LIST_SORT
858 bool "Linked list sorting test"
859 depends on DEBUG_KERNEL
860 help
861 Enable this to turn on 'list_sort()' function test. This test is
862 executed only once during system boot, so affects only boot time.
863
864 If unsure, say N.
865
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866config DEBUG_SG
867 bool "Debug SG table operations"
868 depends on DEBUG_KERNEL
869 help
870 Enable this to turn on checks on scatter-gather tables. This can
871 help find problems with drivers that do not properly initialize
872 their sg tables.
873
874 If unsure, say N.
875
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876config DEBUG_NOTIFIERS
877 bool "Debug notifier call chains"
878 depends on DEBUG_KERNEL
879 help
880 Enable this to turn on sanity checking for notifier call chains.
881 This is most useful for kernel developers to make sure that
882 modules properly unregister themselves from notifier chains.
883 This is a relatively cheap check but if you care about maximum
884 performance, say N.
885
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886config DEBUG_CREDENTIALS
887 bool "Debug credential management"
888 depends on DEBUG_KERNEL
889 help
890 Enable this to turn on some debug checking for credential
891 management. The additional code keeps track of the number of
892 pointers from task_structs to any given cred struct, and checks to
893 see that this number never exceeds the usage count of the cred
894 struct.
895
896 Furthermore, if SELinux is enabled, this also checks that the
897 security pointer in the cred struct is never seen to be invalid.
898
899 If unsure, say N.
900
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901#
902# Select this config option from the architecture Kconfig, if it
52288b66 903# is preferred to always offer frame pointers as a config
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904# option on the architecture (regardless of KERNEL_DEBUG):
905#
906config ARCH_WANT_FRAME_POINTERS
907 bool
908 help
909
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LT
910config FRAME_POINTER
911 bool "Compile the kernel with frame pointers"
b920de1b 912 depends on DEBUG_KERNEL && \
73020415 913 (CRIS || M68K || FRV || UML || \
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914 AVR32 || SUPERH || BLACKFIN || MN10300) || \
915 ARCH_WANT_FRAME_POINTERS
916 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
917 help
918 If you say Y here the resulting kernel image will be slightly
919 larger and slower, but it gives very useful debugging information
920 in case of kernel bugs. (precise oopses/stacktraces/warnings)
1da177e4 921
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922config BOOT_PRINTK_DELAY
923 bool "Delay each boot printk message by N milliseconds"
924 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
925 help
926 This build option allows you to read kernel boot messages
927 by inserting a short delay after each one. The delay is
928 specified in milliseconds on the kernel command line,
929 using "boot_delay=N".
930
931 It is likely that you would also need to use "lpj=M" to preset
932 the "loops per jiffie" value.
933 See a previous boot log for the "lpj" value to use for your
934 system, and then set "lpj=M" before setting "boot_delay=N".
935 NOTE: Using this option may adversely affect SMP systems.
936 I.e., processors other than the first one may not boot up.
8edbb83e 937 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
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RD
938 what it believes to be lockup conditions.
939
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940config RCU_TORTURE_TEST
941 tristate "torture tests for RCU"
942 depends on DEBUG_KERNEL
943 default n
944 help
945 This option provides a kernel module that runs torture tests
946 on the RCU infrastructure. The kernel module may be built
947 after the fact on the running kernel to be tested, if desired.
948
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949 Say Y here if you want RCU torture tests to be built into
950 the kernel.
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951 Say M if you want the RCU torture tests to build as a module.
952 Say N if you are unsure.
8bb31b9d 953
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954config RCU_TORTURE_TEST_RUNNABLE
955 bool "torture tests for RCU runnable by default"
956 depends on RCU_TORTURE_TEST = y
957 default n
958 help
959 This option provides a way to build the RCU torture tests
960 directly into the kernel without them starting up at boot
961 time. You can use /proc/sys/kernel/rcutorture_runnable
962 to manually override this setting. This /proc file is
963 available only when the RCU torture tests have been built
964 into the kernel.
965
966 Say Y here if you want the RCU torture tests to start during
967 boot (you probably don't).
968 Say N here if you want the RCU torture tests to start only
969 after being manually enabled via /proc.
970
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971config RCU_CPU_STALL_TIMEOUT
972 int "RCU CPU stall timeout in seconds"
a00e0d71 973 depends on TREE_RCU || TREE_PREEMPT_RCU
b163760e 974 range 3 300
c896054f 975 default 21
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976 help
977 If a given RCU grace period extends more than the specified
978 number of seconds, a CPU stall warning is printed. If the
979 RCU grace period persists, additional CPU stall warnings are
980 printed at more widely spaced intervals.
981
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982config RCU_CPU_STALL_VERBOSE
983 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
a00e0d71 984 depends on TREE_PREEMPT_RCU
55ec936f 985 default y
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986 help
987 This option causes RCU to printk detailed per-task information
988 for any tasks that are stalling the current RCU grace period.
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989
990 Say N if you are unsure.
991
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992 Say Y if you want to enable such checks.
993
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994config RCU_CPU_STALL_INFO
995 bool "Print additional diagnostics on RCU CPU stall"
996 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
997 default n
998 help
999 For each stalled CPU that is aware of the current RCU grace
1000 period, print out additional per-CPU diagnostic information
1001 regarding scheduling-clock ticks, idle state, and,
1002 for RCU_FAST_NO_HZ kernels, idle-entry state.
1003
1004 Say N if you are unsure.
1005
1006 Say Y if you want to enable such diagnostics.
1007
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1008config RCU_TRACE
1009 bool "Enable tracing for RCU"
1010 depends on DEBUG_KERNEL
1011 help
1012 This option provides tracing in RCU which presents stats
1013 in debugfs for debugging RCU implementation.
1014
1015 Say Y here if you want to enable RCU tracing
1016 Say N if you are unsure.
1017
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1018config KPROBES_SANITY_TEST
1019 bool "Kprobes sanity tests"
1020 depends on DEBUG_KERNEL
1021 depends on KPROBES
1022 default n
1023 help
1024 This option provides for testing basic kprobes functionality on
1025 boot. A sample kprobe, jprobe and kretprobe are inserted and
1026 verified for functionality.
1027
1028 Say N if you are unsure.
1029
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1030config BACKTRACE_SELF_TEST
1031 tristate "Self test for the backtrace code"
1032 depends on DEBUG_KERNEL
1033 default n
1034 help
1035 This option provides a kernel module that can be used to test
1036 the kernel stack backtrace code. This option is not useful
1037 for distributions or general kernels, but only for kernel
1038 developers working on architecture code.
1039
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1040 Note that if you want to also test saved backtraces, you will
1041 have to enable STACKTRACE as well.
1042
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AV
1043 Say N if you are unsure.
1044
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1045config DEBUG_BLOCK_EXT_DEVT
1046 bool "Force extended block device numbers and spread them"
1047 depends on DEBUG_KERNEL
1048 depends on BLOCK
759f8ca3 1049 default n
870d6656 1050 help
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1051 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1052 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1053 YOU ARE DOING. Distros, please enable this and fix whatever
1054 is broken.
1055
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1056 Conventionally, block device numbers are allocated from
1057 predetermined contiguous area. However, extended block area
1058 may introduce non-contiguous block device numbers. This
1059 option forces most block device numbers to be allocated from
1060 the extended space and spreads them to discover kernel or
1061 userland code paths which assume predetermined contiguous
1062 device number allocation.
1063
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1064 Note that turning on this debug option shuffles all the
1065 device numbers for all IDE and SCSI devices including libata
1066 ones, so root partition specified using device number
1067 directly (via rdev or root=MAJ:MIN) won't work anymore.
1068 Textual device names (root=/dev/sdXn) will continue to work.
1069
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1070 Say N if you are unsure.
1071
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1072config DEBUG_FORCE_WEAK_PER_CPU
1073 bool "Force weak per-cpu definitions"
1074 depends on DEBUG_KERNEL
1075 help
1076 s390 and alpha require percpu variables in modules to be
1077 defined weak to work around addressing range issue which
1078 puts the following two restrictions on percpu variable
1079 definitions.
1080
1081 1. percpu symbols must be unique whether static or not
1082 2. percpu variables can't be defined inside a function
1083
1084 To ensure that generic code follows the above rules, this
1085 option forces all percpu variables to be defined as weak.
1086
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1087config DEBUG_PER_CPU_MAPS
1088 bool "Debug access to per_cpu maps"
1089 depends on DEBUG_KERNEL
1090 depends on SMP
1091 help
1092 Say Y to verify that the per_cpu map being accessed has
1093 been set up. This adds a fair amount of code to kernel memory
1094 and decreases performance.
1095
1096 Say N if unsure.
1097
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1098config LKDTM
1099 tristate "Linux Kernel Dump Test Tool Module"
0347af4e 1100 depends on DEBUG_FS
fddd9cf8 1101 depends on BLOCK
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1102 default n
1103 help
1104 This module enables testing of the different dumping mechanisms by
1105 inducing system failures at predefined crash points.
1106 If you don't need it: say N
1107 Choose M here to compile this code as a module. The module will be
1108 called lkdtm.
1109
1110 Documentation on how to use the module can be found in
0347af4e 1111 Documentation/fault-injection/provoke-crashes.txt
6ff1cb35 1112
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1113config NOTIFIER_ERROR_INJECTION
1114 tristate "Notifier error injection"
1115 depends on DEBUG_KERNEL
1116 select DEBUG_FS
1117 help
e41e85cc 1118 This option provides the ability to inject artificial errors to
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1119 specified notifier chain callbacks. It is useful to test the error
1120 handling of notifier call chain failures.
1121
1122 Say N if unsure.
1123
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1124config CPU_NOTIFIER_ERROR_INJECT
1125 tristate "CPU notifier error injection module"
f5a9f52e 1126 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
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1127 help
1128 This option provides a kernel module that can be used to test
e41e85cc 1129 the error handling of the cpu notifiers by injecting artificial
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1130 errors to CPU notifier chain callbacks. It is controlled through
1131 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1132
1133 If the notifier call chain should be failed with some events
1134 notified, write the error code to "actions/<notifier event>/error".
1135
1136 Example: Inject CPU offline error (-1 == -EPERM)
1137
1138 # cd /sys/kernel/debug/notifier-error-inject/cpu
1139 # echo -1 > actions/CPU_DOWN_PREPARE/error
1140 # echo 0 > /sys/devices/system/cpu/cpu1/online
1141 bash: echo: write error: Operation not permitted
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1142
1143 To compile this code as a module, choose M here: the module will
1144 be called cpu-notifier-error-inject.
1145
1146 If unsure, say N.
1147
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1148config PM_NOTIFIER_ERROR_INJECT
1149 tristate "PM notifier error injection module"
1150 depends on PM && NOTIFIER_ERROR_INJECTION
1151 default m if PM_DEBUG
1152 help
e41e85cc 1153 This option provides the ability to inject artificial errors to
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AM
1154 PM notifier chain callbacks. It is controlled through debugfs
1155 interface /sys/kernel/debug/notifier-error-inject/pm
1156
1157 If the notifier call chain should be failed with some events
1158 notified, write the error code to "actions/<notifier event>/error".
1159
1160 Example: Inject PM suspend error (-12 = -ENOMEM)
1161
1162 # cd /sys/kernel/debug/notifier-error-inject/pm/
1163 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1164 # echo mem > /sys/power/state
1165 bash: echo: write error: Cannot allocate memory
1166
1167 To compile this code as a module, choose M here: the module will
1168 be called pm-notifier-error-inject.
1169
1170 If unsure, say N.
1171
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1172config MEMORY_NOTIFIER_ERROR_INJECT
1173 tristate "Memory hotplug notifier error injection module"
1174 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1175 help
e41e85cc 1176 This option provides the ability to inject artificial errors to
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1177 memory hotplug notifier chain callbacks. It is controlled through
1178 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
1179
1180 If the notifier call chain should be failed with some events
1181 notified, write the error code to "actions/<notifier event>/error".
1182
1183 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
1184
1185 # cd /sys/kernel/debug/notifier-error-inject/memory
1186 # echo -12 > actions/MEM_GOING_OFFLINE/error
1187 # echo offline > /sys/devices/system/memory/memoryXXX/state
1188 bash: echo: write error: Cannot allocate memory
1189
1190 To compile this code as a module, choose M here: the module will
1191 be called pSeries-reconfig-notifier-error-inject.
1192
1193 If unsure, say N.
1194
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1195config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1196 tristate "OF reconfig notifier error injection module"
1197 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
08dfb4dd 1198 help
e41e85cc 1199 This option provides the ability to inject artificial errors to
d526e85f 1200 OF reconfig notifier chain callbacks. It is controlled
08dfb4dd 1201 through debugfs interface under
d526e85f 1202 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
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1203
1204 If the notifier call chain should be failed with some events
1205 notified, write the error code to "actions/<notifier event>/error".
1206
1207 To compile this code as a module, choose M here: the module will
1208 be called memory-notifier-error-inject.
1209
1210 If unsure, say N.
1211
6ff1cb35 1212config FAULT_INJECTION
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1213 bool "Fault-injection framework"
1214 depends on DEBUG_KERNEL
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1215 help
1216 Provide fault-injection framework.
1217 For more details, see Documentation/fault-injection/.
6ff1cb35 1218
8a8b6502 1219config FAILSLAB
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1220 bool "Fault-injection capability for kmalloc"
1221 depends on FAULT_INJECTION
773ff60e 1222 depends on SLAB || SLUB
8a8b6502 1223 help
1ab8509a 1224 Provide fault-injection capability for kmalloc.
8a8b6502 1225
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1226config FAIL_PAGE_ALLOC
1227 bool "Fault-injection capabilitiy for alloc_pages()"
1ab8509a 1228 depends on FAULT_INJECTION
933e312e 1229 help
1ab8509a 1230 Provide fault-injection capability for alloc_pages().
933e312e 1231
c17bb495 1232config FAIL_MAKE_REQUEST
86327d19 1233 bool "Fault-injection capability for disk IO"
581d4e28 1234 depends on FAULT_INJECTION && BLOCK
c17bb495 1235 help
1ab8509a 1236 Provide fault-injection capability for disk IO.
c17bb495 1237
581d4e28 1238config FAIL_IO_TIMEOUT
f4d01439 1239 bool "Fault-injection capability for faking disk interrupts"
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JA
1240 depends on FAULT_INJECTION && BLOCK
1241 help
1242 Provide fault-injection capability on end IO handling. This
1243 will make the block layer "forget" an interrupt as configured,
1244 thus exercising the error handling.
1245
1246 Only works with drivers that use the generic timeout handling,
1247 for others it wont do anything.
1248
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1249config FAIL_MMC_REQUEST
1250 bool "Fault-injection capability for MMC IO"
1251 select DEBUG_FS
1252 depends on FAULT_INJECTION && MMC
1253 help
1254 Provide fault-injection capability for MMC IO.
1255 This will make the mmc core return data errors. This is
1256 useful to test the error handling in the mmc block device
1257 and to test how the mmc host driver handles retries from
1258 the block device.
1259
6ff1cb35
AM
1260config FAULT_INJECTION_DEBUG_FS
1261 bool "Debugfs entries for fault-injection capabilities"
1ab8509a 1262 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
6ff1cb35 1263 help
1ab8509a 1264 Enable configuration of fault-injection capabilities via debugfs.
1df49008
AM
1265
1266config FAULT_INJECTION_STACKTRACE_FILTER
1267 bool "stacktrace filter for fault-injection capabilities"
1268 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
6d690dca 1269 depends on !X86_64
1df49008 1270 select STACKTRACE
89bace65 1271 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1df49008
AM
1272 help
1273 Provide stacktrace filter for fault-injection capabilities
267c4025 1274
9745512c
AV
1275config LATENCYTOP
1276 bool "Latency measuring infrastructure"
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RD
1277 depends on HAVE_LATENCYTOP_SUPPORT
1278 depends on DEBUG_KERNEL
1279 depends on STACKTRACE_SUPPORT
1280 depends on PROC_FS
89bace65 1281 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
9745512c
AV
1282 select KALLSYMS
1283 select KALLSYMS_ALL
1284 select STACKTRACE
1285 select SCHEDSTATS
1286 select SCHED_DEBUG
9745512c
AV
1287 help
1288 Enable this option if you want to use the LatencyTOP tool
1289 to find out which userspace is blocking on what kernel operations.
1290
6a11f75b 1291source mm/Kconfig.debug
16444a8a
ACM
1292source kernel/trace/Kconfig
1293
910a742d
ML
1294config RBTREE_TEST
1295 tristate "Red-Black tree test"
1296 depends on m && DEBUG_KERNEL
1297 help
1298 A benchmark measuring the performance of the rbtree library.
1299 Also includes rbtree invariant checks.
1300
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ML
1301config INTERVAL_TREE_TEST
1302 tristate "Interval tree test"
1303 depends on m && DEBUG_KERNEL
1304 help
1305 A benchmark measuring the performance of the interval tree library
1306
f212ec4b 1307config PROVIDE_OHCI1394_DMA_INIT
080de8c2 1308 bool "Remote debugging over FireWire early on boot"
f212ec4b
BK
1309 depends on PCI && X86
1310 help
1311 If you want to debug problems which hang or crash the kernel early
1312 on boot and the crashing machine has a FireWire port, you can use
1313 this feature to remotely access the memory of the crashed machine
1314 over FireWire. This employs remote DMA as part of the OHCI1394
1315 specification which is now the standard for FireWire controllers.
1316
1317 With remote DMA, you can monitor the printk buffer remotely using
1318 firescope and access all memory below 4GB using fireproxy from gdb.
1319 Even controlling a kernel debugger is possible using remote DMA.
1320
1321 Usage:
1322
1323 If ohci1394_dma=early is used as boot parameter, it will initialize
1324 all OHCI1394 controllers which are found in the PCI config space.
1325
1326 As all changes to the FireWire bus such as enabling and disabling
1327 devices cause a bus reset and thereby disable remote DMA for all
1328 devices, be sure to have the cable plugged and FireWire enabled on
1329 the debugging host before booting the debug target for debugging.
1330
1331 This code (~1k) is freed after boot. By then, the firewire stack
1332 in charge of the OHCI-1394 controllers should be used instead.
1333
1334 See Documentation/debugging-via-ohci1394.txt for more information.
9745512c 1335
080de8c2
SR
1336config FIREWIRE_OHCI_REMOTE_DMA
1337 bool "Remote debugging over FireWire with firewire-ohci"
1338 depends on FIREWIRE_OHCI
1339 help
1340 This option lets you use the FireWire bus for remote debugging
1341 with help of the firewire-ohci driver. It enables unfiltered
1342 remote DMA in firewire-ohci.
1343 See Documentation/debugging-via-ohci1394.txt for more information.
1344
1345 If unsure, say N.
1346
152de30b 1347config BUILD_DOCSRC
3794f3e8
RD
1348 bool "Build targets in Documentation/ tree"
1349 depends on HEADERS_CHECK
1350 help
1351 This option attempts to build objects from the source files in the
1352 kernel Documentation/ tree.
1353
1354 Say N if you are unsure.
1355
e9d376f0 1356config DYNAMIC_DEBUG
86151fdf 1357 bool "Enable dynamic printk() support"
346e15be
JB
1358 default n
1359 depends on PRINTK
86151fdf 1360 depends on DEBUG_FS
346e15be
JB
1361 help
1362
1363 Compiles debug level messages into the kernel, which would not
1364 otherwise be available at runtime. These messages can then be
86151fdf
JB
1365 enabled/disabled based on various levels of scope - per source file,
1366 function, module, format string, and line number. This mechanism
29e36c9f
JC
1367 implicitly compiles in all pr_debug() and dev_dbg() calls, which
1368 enlarges the kernel text size by about 2%.
1369
1370 If a source file is compiled with DEBUG flag set, any
1371 pr_debug() calls in it are enabled by default, but can be
1372 disabled at runtime as below. Note that DEBUG flag is
1373 turned on by many CONFIG_*DEBUG* options.
346e15be
JB
1374
1375 Usage:
1376
2b2f68b5 1377 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
86151fdf
JB
1378 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1379 filesystem must first be mounted before making use of this feature.
2b2f68b5 1380 We refer the control file as: <debugfs>/dynamic_debug/control. This
86151fdf
JB
1381 file contains a list of the debug statements that can be enabled. The
1382 format for each line of the file is:
346e15be 1383
86151fdf 1384 filename:lineno [module]function flags format
346e15be 1385
86151fdf
JB
1386 filename : source file of the debug statement
1387 lineno : line number of the debug statement
1388 module : module that contains the debug statement
1389 function : function that contains the debug statement
29e36c9f 1390 flags : '=p' means the line is turned 'on' for printing
86151fdf 1391 format : the format used for the debug statement
346e15be
JB
1392
1393 From a live system:
1394
2b2f68b5 1395 nullarbor:~ # cat <debugfs>/dynamic_debug/control
86151fdf 1396 # filename:lineno [module]function flags format
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JC
1397 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1398 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1399 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
346e15be 1400
86151fdf 1401 Example usage:
346e15be 1402
86151fdf
JB
1403 // enable the message at line 1603 of file svcsock.c
1404 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
2b2f68b5 1405 <debugfs>/dynamic_debug/control
346e15be 1406
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JB
1407 // enable all the messages in file svcsock.c
1408 nullarbor:~ # echo -n 'file svcsock.c +p' >
2b2f68b5 1409 <debugfs>/dynamic_debug/control
346e15be 1410
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JB
1411 // enable all the messages in the NFS server module
1412 nullarbor:~ # echo -n 'module nfsd +p' >
2b2f68b5 1413 <debugfs>/dynamic_debug/control
346e15be 1414
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JB
1415 // enable all 12 messages in the function svc_process()
1416 nullarbor:~ # echo -n 'func svc_process +p' >
2b2f68b5 1417 <debugfs>/dynamic_debug/control
346e15be 1418
86151fdf
JB
1419 // disable all 12 messages in the function svc_process()
1420 nullarbor:~ # echo -n 'func svc_process -p' >
2b2f68b5 1421 <debugfs>/dynamic_debug/control
346e15be 1422
86151fdf 1423 See Documentation/dynamic-debug-howto.txt for additional information.
346e15be 1424
5ee00bd4
JR
1425config DMA_API_DEBUG
1426 bool "Enable debugging of DMA-API usage"
1427 depends on HAVE_DMA_API_DEBUG
1428 help
1429 Enable this option to debug the use of the DMA API by device drivers.
1430 With this option you will be able to detect common bugs in device
1431 drivers like double-freeing of DMA mappings or freeing mappings that
1432 were never allocated.
1433 This option causes a performance degredation. Use only if you want
1434 to debug device drivers. If unsure, say N.
346e15be 1435
86a89380
LB
1436config ATOMIC64_SELFTEST
1437 bool "Perform an atomic64_t self-test at boot"
1438 help
1439 Enable this option to test the atomic64_t functions at boot.
1440
1441 If unsure, say N.
1442
400fb7f6
DW
1443config ASYNC_RAID6_TEST
1444 tristate "Self test for hardware accelerated raid6 recovery"
1445 depends on ASYNC_RAID6_RECOV
1446 select ASYNC_MEMCPY
1447 ---help---
1448 This is a one-shot self test that permutes through the
1449 recovery of all the possible two disk failure scenarios for a
1450 N-disk array. Recovery is performed with the asynchronous
1451 raid6 recovery routines, and will optionally use an offload
1452 engine if one is available.
1453
1454 If unsure, say N.
1455
267c4025 1456source "samples/Kconfig"
dc7d5527
JW
1457
1458source "lib/Kconfig.kgdb"
0a4af3b0
PE
1459
1460source "lib/Kconfig.kmemcheck"
33ee3b2e
AD
1461
1462config TEST_KSTRTOX
1463 tristate "Test kstrto*() family of functions at runtime"