block: fix use-after-free in seq file
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / lib / Kconfig.debug
CommitLineData
1da177e4
LT
1
2config PRINTK_TIME
3 bool "Show timing information on printks"
d3b8b6e5 4 depends on PRINTK
1da177e4 5 help
649e6ee3
KS
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
5af5bcb8
MSB
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
de488443
JG
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
cebc04ba
AM
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
35bb5b1e
AK
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
1da177e4
LT
55config MAGIC_SYSRQ
56 bool "Magic SysRq key"
f346f4b3 57 depends on !UML
1da177e4
LT
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
99657c78
RD
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
1873e870
AK
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
f71d20e9
AV
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
bf4735a4
DM
102config DEBUG_FS
103 bool "Debug Filesystem"
bf4735a4
DM
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
ff543332
RD
109 For detailed documentation on the debugfs API, see
110 Documentation/DocBook/filesystems.
111
bf4735a4
DM
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
91341d4b
SR
128config DEBUG_SECTION_MISMATCH
129 bool "Enable full Section mismatch analysis"
91341d4b
SR
130 help
131 The section mismatch analysis checks if there are illegal
132 references from one section to another section.
e809ab01
MW
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.
e809ab01 136 In the code, functions and variables are annotated with
6ae14171 137 __init, __cpuinit, etc. (see the full list in include/linux/init.h),
d6fbfa4f 138 which results in the code/data being placed in specific sections.
e809ab01
MW
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.
e809ab01
MW
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
91341d4b
SR
151 introduced.
152 Running the analysis for each module/built-in.o file
e809ab01
MW
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
f346f4b3
AB
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
a304e1b8
DW
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
58687acb
DZ
174config LOCKUP_DETECTOR
175 bool "Detect Hard and Soft Lockups"
dea20a3f 176 depends on DEBUG_KERNEL && !S390
8446f1d3 177 help
58687acb
DZ
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
58687acb
DZ
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
58687acb
DZ
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
5f329089
FLVC
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
8f1f66ed
JB
199 def_bool y
200 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
201 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
8446f1d3 202
fef2c9bc
DZ
203config BOOTPARAM_HARDLOCKUP_PANIC
204 bool "Panic (Reboot) On Hard Lockups"
8f1f66ed 205 depends on HARDLOCKUP_DETECTOR
fef2c9bc
DZ
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
5f329089
FLVC
209 mode with interrupts disabled for more than 10 seconds (configurable
210 using the watchdog_thresh sysctl).
fef2c9bc
DZ
211
212 Say N if unsure.
213
214config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
215 int
8f1f66ed 216 depends on HARDLOCKUP_DETECTOR
fef2c9bc
DZ
217 range 0 1
218 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
219 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
220
9c44bc03
IM
221config BOOTPARAM_SOFTLOCKUP_PANIC
222 bool "Panic (Reboot) On Soft Lockups"
89d7ce2a 223 depends on LOCKUP_DETECTOR
9c44bc03
IM
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
5f329089
FLVC
227 mode for more than 20 seconds (configurable using the watchdog_thresh
228 sysctl), without giving other tasks a chance to run.
9c44bc03
IM
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
9c44bc03
IM
241 range 0 1
242 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
243 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
244
2a01bb38 245config PANIC_ON_OOPS
76e84026 246 bool "Panic on Oops"
2a01bb38
KM
247 help
248 Say Y here to enable the kernel to panic when it oopses. This
249 has the same effect as setting oops=panic on the kernel command
250 line.
251
252 This feature is useful to ensure that the kernel does not do
253 anything erroneous after an oops which could result in data
254 corruption or other issues.
255
256 Say N if unsure.
257
258config PANIC_ON_OOPS_VALUE
259 int
260 range 0 1
261 default 0 if !PANIC_ON_OOPS
262 default 1 if PANIC_ON_OOPS
263
e162b39a
MSB
264config DETECT_HUNG_TASK
265 bool "Detect Hung Tasks"
266 depends on DEBUG_KERNEL
8edbb83e 267 default LOCKUP_DETECTOR
e162b39a
MSB
268 help
269 Say Y here to enable the kernel to detect "hung tasks",
270 which are bugs that cause the task to be stuck in
271 uninterruptible "D" state indefinitiley.
272
273 When a hung task is detected, the kernel will print the
274 current stack trace (which you should report), but the
275 task will stay in uninterruptible state. If lockdep is
276 enabled then all held locks will also be reported. This
277 feature has negligible overhead.
278
e11feaa1
JM
279config DEFAULT_HUNG_TASK_TIMEOUT
280 int "Default timeout for hung task detection (in seconds)"
281 depends on DETECT_HUNG_TASK
282 default 120
283 help
284 This option controls the default timeout (in seconds) used
285 to determine when a task has become non-responsive and should
286 be considered hung.
287
c51eaacc
JZ
288 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
289 sysctl or by writing a value to
290 /proc/sys/kernel/hung_task_timeout_secs.
e11feaa1
JM
291
292 A timeout of 0 disables the check. The default is two minutes.
293 Keeping the default should be fine in most cases.
294
e162b39a
MSB
295config BOOTPARAM_HUNG_TASK_PANIC
296 bool "Panic (Reboot) On Hung Tasks"
297 depends on DETECT_HUNG_TASK
298 help
299 Say Y here to enable the kernel to panic on "hung tasks",
300 which are bugs that cause the kernel to leave a task stuck
301 in uninterruptible "D" state.
302
303 The panic can be used in combination with panic_timeout,
304 to cause the system to reboot automatically after a
305 hung task has been detected. This feature is useful for
306 high-availability systems that have uptime guarantees and
307 where a hung tasks must be resolved ASAP.
308
309 Say N if unsure.
310
311config BOOTPARAM_HUNG_TASK_PANIC_VALUE
312 int
313 depends on DETECT_HUNG_TASK
314 range 0 1
315 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
316 default 1 if BOOTPARAM_HUNG_TASK_PANIC
317
b642b6d3
IM
318config SCHED_DEBUG
319 bool "Collect scheduler debugging info"
320 depends on DEBUG_KERNEL && PROC_FS
321 default y
322 help
323 If you say Y here, the /proc/sched_debug file will be provided
324 that can help debug the scheduler. The runtime overhead of this
325 option is minimal.
326
1da177e4
LT
327config SCHEDSTATS
328 bool "Collect scheduler statistics"
329 depends on DEBUG_KERNEL && PROC_FS
330 help
331 If you say Y here, additional code will be inserted into the
332 scheduler and related routines to collect statistics about
333 scheduler behavior and provide them in /proc/schedstat. These
334 stats may be useful for both tuning and debugging the scheduler
335 If you aren't debugging the scheduler or trying to tune a specific
336 application, you can say N to avoid the very slight overhead
337 this adds.
338
82f67cd9
IM
339config TIMER_STATS
340 bool "Collect kernel timers statistics"
341 depends on DEBUG_KERNEL && PROC_FS
342 help
343 If you say Y here, additional code will be inserted into the
344 timer routines to collect statistics about kernel timers being
345 reprogrammed. The statistics can be read from /proc/timer_stats.
346 The statistics collection is started by writing 1 to /proc/timer_stats,
347 writing 0 stops it. This feature is useful to collect information
c1a834dc
IM
348 about timer usage patterns in kernel and userspace. This feature
349 is lightweight if enabled in the kernel config but not activated
350 (it defaults to deactivated on bootup and will only be activated
351 if some application like powertop activates it explicitly).
82f67cd9 352
3ac7fe5a
TG
353config DEBUG_OBJECTS
354 bool "Debug object operations"
355 depends on DEBUG_KERNEL
356 help
357 If you say Y here, additional code will be inserted into the
358 kernel to track the life time of various objects and validate
359 the operations on those objects.
360
361config DEBUG_OBJECTS_SELFTEST
362 bool "Debug objects selftest"
363 depends on DEBUG_OBJECTS
364 help
365 This enables the selftest of the object debug code.
366
367config DEBUG_OBJECTS_FREE
368 bool "Debug objects in freed memory"
369 depends on DEBUG_OBJECTS
370 help
371 This enables checks whether a k/v free operation frees an area
372 which contains an object which has not been deactivated
373 properly. This can make kmalloc/kfree-intensive workloads
374 much slower.
375
c6f3a97f
TG
376config DEBUG_OBJECTS_TIMERS
377 bool "Debug timer objects"
378 depends on DEBUG_OBJECTS
379 help
380 If you say Y here, additional code will be inserted into the
381 timer routines to track the life time of timer objects and
382 validate the timer operations.
383
dc186ad7
TG
384config DEBUG_OBJECTS_WORK
385 bool "Debug work objects"
386 depends on DEBUG_OBJECTS
387 help
388 If you say Y here, additional code will be inserted into the
389 work queue routines to track the life time of work objects and
390 validate the work operations.
391
551d55a9
MD
392config DEBUG_OBJECTS_RCU_HEAD
393 bool "Debug RCU callbacks objects"
fc2ecf7e 394 depends on DEBUG_OBJECTS
551d55a9
MD
395 help
396 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
397
e2852ae8
TH
398config DEBUG_OBJECTS_PERCPU_COUNTER
399 bool "Debug percpu counter objects"
400 depends on DEBUG_OBJECTS
401 help
402 If you say Y here, additional code will be inserted into the
403 percpu counter routines to track the life time of percpu counter
404 objects and validate the percpu counter operations.
405
3ae70205
IM
406config DEBUG_OBJECTS_ENABLE_DEFAULT
407 int "debug_objects bootup default value (0-1)"
408 range 0 1
409 default "1"
410 depends on DEBUG_OBJECTS
411 help
412 Debug objects boot parameter default value
413
1da177e4 414config DEBUG_SLAB
4a2f0acf 415 bool "Debug slab memory allocations"
7d46d9e6 416 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
1da177e4
LT
417 help
418 Say Y here to have the kernel do limited verification on memory
419 allocation as well as poisoning memory on free to catch use of freed
420 memory. This can make kmalloc/kfree-intensive workloads much slower.
421
871751e2
AV
422config DEBUG_SLAB_LEAK
423 bool "Memory leak debugging"
424 depends on DEBUG_SLAB
425
f0630fff
CL
426config SLUB_DEBUG_ON
427 bool "SLUB debugging on by default"
7d46d9e6 428 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
f0630fff
CL
429 default n
430 help
431 Boot with debugging on by default. SLUB boots by default with
432 the runtime debug capabilities switched off. Enabling this is
433 equivalent to specifying the "slub_debug" parameter on boot.
434 There is no support for more fine grained debug control like
435 possible with slub_debug=xxx. SLUB debugging may be switched
436 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
437 "slub_debug=-".
438
8ff12cfc
CL
439config SLUB_STATS
440 default n
441 bool "Enable SLUB performance statistics"
ab4d5ed5 442 depends on SLUB && SYSFS
8ff12cfc
CL
443 help
444 SLUB statistics are useful to debug SLUBs allocation behavior in
445 order find ways to optimize the allocator. This should never be
446 enabled for production use since keeping statistics slows down
447 the allocator by a few percentage points. The slabinfo command
448 supports the determination of the most active slabs to figure
449 out which slabs are relevant to a particular load.
450 Try running: slabinfo -DA
451
b69ec42b
CM
452config HAVE_DEBUG_KMEMLEAK
453 bool
454
3bba00d7
CM
455config DEBUG_KMEMLEAK
456 bool "Kernel memory leak detector"
525c1f92 457 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
79e0d9bd 458 select DEBUG_FS
3bba00d7
CM
459 select STACKTRACE if STACKTRACE_SUPPORT
460 select KALLSYMS
b60e26a2 461 select CRC32
3bba00d7
CM
462 help
463 Say Y here if you want to enable the memory leak
464 detector. The memory allocation/freeing is traced in a way
465 similar to the Boehm's conservative garbage collector, the
466 difference being that the orphan objects are not freed but
467 only shown in /sys/kernel/debug/kmemleak. Enabling this
468 feature will introduce an overhead to memory
469 allocations. See Documentation/kmemleak.txt for more
470 details.
471
bf96d1e3
CM
472 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
473 of finding leaks due to the slab objects poisoning.
474
3bba00d7
CM
475 In order to access the kmemleak file, debugfs needs to be
476 mounted (usually at /sys/kernel/debug).
477
a9d9058a
CM
478config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
479 int "Maximum kmemleak early log entries"
480 depends on DEBUG_KMEMLEAK
dfcc3e6a 481 range 200 40000
a9d9058a
CM
482 default 400
483 help
484 Kmemleak must track all the memory allocations to avoid
485 reporting false positives. Since memory may be allocated or
486 freed before kmemleak is initialised, an early log buffer is
487 used to store these actions. If kmemleak reports "early log
488 buffer exceeded", please increase this value.
489
0822ee4a
CM
490config DEBUG_KMEMLEAK_TEST
491 tristate "Simple test for the kernel memory leak detector"
9718269a 492 depends on DEBUG_KMEMLEAK && m
0822ee4a 493 help
9718269a 494 This option enables a module that explicitly leaks memory.
0822ee4a
CM
495
496 If unsure, say N.
497
ab0155a2
JB
498config DEBUG_KMEMLEAK_DEFAULT_OFF
499 bool "Default kmemleak to off"
500 depends on DEBUG_KMEMLEAK
501 help
502 Say Y here to disable kmemleak by default. It can then be enabled
503 on the command line via kmemleak=on.
504
1da177e4
LT
505config DEBUG_PREEMPT
506 bool "Debug preemptible kernel"
01deab98 507 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1da177e4
LT
508 default y
509 help
510 If you say Y here then the kernel will use a debug variant of the
511 commonly used smp_processor_id() function and will print warnings
512 if kernel code uses it in a preemption-unsafe way. Also, the kernel
513 will detect preemption count underflows.
514
e7eebaf6
IM
515config DEBUG_RT_MUTEXES
516 bool "RT Mutex debugging, deadlock detection"
e7eebaf6
IM
517 depends on DEBUG_KERNEL && RT_MUTEXES
518 help
519 This allows rt mutex semantics violations and rt mutex related
520 deadlocks (lockups) to be detected and reported automatically.
521
522config DEBUG_PI_LIST
523 bool
524 default y
525 depends on DEBUG_RT_MUTEXES
526
61a87122
TG
527config RT_MUTEX_TESTER
528 bool "Built-in scriptable tester for rt-mutexes"
a1583d3e 529 depends on DEBUG_KERNEL && RT_MUTEXES
61a87122
TG
530 help
531 This option enables a rt-mutex tester.
532
1da177e4 533config DEBUG_SPINLOCK
4d9f34ad 534 bool "Spinlock and rw-lock debugging: basic checks"
1da177e4 535 depends on DEBUG_KERNEL
e335e3eb 536 select UNINLINE_SPIN_UNLOCK
1da177e4
LT
537 help
538 Say Y here and build SMP to catch missing spinlock initialization
539 and certain other kinds of spinlock errors commonly made. This is
540 best used in conjunction with the NMI watchdog so that spinlock
541 deadlocks are also debuggable.
542
4d9f34ad
IM
543config DEBUG_MUTEXES
544 bool "Mutex debugging: basic checks"
545 depends on DEBUG_KERNEL
546 help
547 This feature allows mutex semantics violations to be detected and
548 reported.
549
4d9f34ad
IM
550config DEBUG_LOCK_ALLOC
551 bool "Lock debugging: detect incorrect freeing of live locks"
517e7aa5 552 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad
IM
553 select DEBUG_SPINLOCK
554 select DEBUG_MUTEXES
4d9f34ad
IM
555 select LOCKDEP
556 help
557 This feature will check whether any held lock (spinlock, rwlock,
558 mutex or rwsem) is incorrectly freed by the kernel, via any of the
559 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
560 vfree(), etc.), whether a live lock is incorrectly reinitialized via
561 spin_lock_init()/mutex_init()/etc., or whether there is any lock
562 held during task exit.
563
564config PROVE_LOCKING
565 bool "Lock debugging: prove locking correctness"
517e7aa5 566 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad
IM
567 select LOCKDEP
568 select DEBUG_SPINLOCK
569 select DEBUG_MUTEXES
4d9f34ad 570 select DEBUG_LOCK_ALLOC
46b93b74 571 select TRACE_IRQFLAGS
4d9f34ad
IM
572 default n
573 help
574 This feature enables the kernel to prove that all locking
575 that occurs in the kernel runtime is mathematically
576 correct: that under no circumstance could an arbitrary (and
577 not yet triggered) combination of observed locking
578 sequences (on an arbitrary number of CPUs, running an
579 arbitrary number of tasks and interrupt contexts) cause a
580 deadlock.
581
582 In short, this feature enables the kernel to report locking
583 related deadlocks before they actually occur.
584
585 The proof does not depend on how hard and complex a
586 deadlock scenario would be to trigger: how many
587 participant CPUs, tasks and irq-contexts would be needed
588 for it to trigger. The proof also does not depend on
589 timing: if a race and a resulting deadlock is possible
590 theoretically (no matter how unlikely the race scenario
591 is), it will be proven so and will immediately be
592 reported by the kernel (once the event is observed that
593 makes the deadlock theoretically possible).
594
595 If a deadlock is impossible (i.e. the locking rules, as
596 observed by the kernel, are mathematically correct), the
597 kernel reports nothing.
598
599 NOTE: this feature can also be enabled for rwlocks, mutexes
600 and rwsems - in which case all dependencies between these
601 different locking variants are observed and mapped too, and
602 the proof of observed correctness is also maintained for an
603 arbitrary combination of these separate locking variants.
604
605 For more details, see Documentation/lockdep-design.txt.
606
607config LOCKDEP
608 bool
517e7aa5 609 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad 610 select STACKTRACE
79aac889 611 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
4d9f34ad
IM
612 select KALLSYMS
613 select KALLSYMS_ALL
614
f20786ff 615config LOCK_STAT
fdfb870f 616 bool "Lock usage statistics"
f20786ff
PZ
617 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
618 select LOCKDEP
619 select DEBUG_SPINLOCK
620 select DEBUG_MUTEXES
621 select DEBUG_LOCK_ALLOC
622 default n
623 help
624 This feature enables tracking lock contention points
625
a560aa48
PZ
626 For more details, see Documentation/lockstat.txt
627
dd8b1cf6
FW
628 This also enables lock events required by "perf lock",
629 subcommand of perf.
630 If you want to use "perf lock", you also need to turn on
631 CONFIG_EVENT_TRACING.
84c6f88f
HM
632
633 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
dd8b1cf6 634 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
84c6f88f 635
4d9f34ad
IM
636config DEBUG_LOCKDEP
637 bool "Lock dependency engine debugging"
517e7aa5 638 depends on DEBUG_KERNEL && LOCKDEP
4d9f34ad
IM
639 help
640 If you say Y here, the lock dependency engine will do
641 additional runtime checks to debug itself, at the price
642 of more runtime overhead.
643
644config TRACE_IRQFLAGS
645 bool
46b93b74
SR
646 help
647 Enables hooks to interrupt enabling and disabling for
648 either tracing or lock debugging.
4d9f34ad 649
d902db1e
FW
650config DEBUG_ATOMIC_SLEEP
651 bool "Sleep inside atomic section checking"
e8f7c70f 652 select PREEMPT_COUNT
1da177e4
LT
653 depends on DEBUG_KERNEL
654 help
655 If you say Y here, various routines which may sleep will become very
d902db1e
FW
656 noisy if they are called inside atomic sections: when a spinlock is
657 held, inside an rcu read side critical section, inside preempt disabled
658 sections, inside an interrupt, etc...
1da177e4 659
cae2ed9a
IM
660config DEBUG_LOCKING_API_SELFTESTS
661 bool "Locking API boot-time self-tests"
662 depends on DEBUG_KERNEL
663 help
664 Say Y here if you want the kernel to run a short self-test during
665 bootup. The self-test checks whether common types of locking bugs
666 are detected by debugging mechanisms or not. (if you disable
667 lock debugging then those bugs wont be detected of course.)
668 The following locking APIs are covered: spinlocks, rwlocks,
669 mutexes and rwsems.
670
8637c099
IM
671config STACKTRACE
672 bool
673 depends on STACKTRACE_SUPPORT
674
5ca43f6c
SB
675config DEBUG_STACK_USAGE
676 bool "Stack utilization instrumentation"
79f83c02 677 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
5ca43f6c
SB
678 help
679 Enables the display of the minimum amount of free stack which each
680 task has ever had available in the sysrq-T and sysrq-P debug output.
681
682 This option will slow down process creation somewhat.
683
1da177e4
LT
684config DEBUG_KOBJECT
685 bool "kobject debugging"
686 depends on DEBUG_KERNEL
687 help
688 If you say Y here, some extra kobject debugging messages will be sent
689 to the syslog.
690
691config DEBUG_HIGHMEM
692 bool "Highmem debugging"
693 depends on DEBUG_KERNEL && HIGHMEM
694 help
695 This options enables addition error checking for high memory systems.
696 Disable for production systems.
697
9b2a60c4
CM
698config HAVE_DEBUG_BUGVERBOSE
699 bool
700
1da177e4 701config DEBUG_BUGVERBOSE
6a108a14 702 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
9b2a60c4 703 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
8420e7ef 704 default y
1da177e4
LT
705 help
706 Say Y here to make BUG() panics output the file name and line number
707 of the BUG call as well as the EIP and oops trace. This aids
708 debugging but costs about 70-100K of memory.
709
710config DEBUG_INFO
711 bool "Compile the kernel with debug info"
712 depends on DEBUG_KERNEL
713 help
714 If you say Y here the resulting kernel image will include
715 debugging info resulting in a larger kernel image.
b72e53f8
AD
716 This adds debug symbols to the kernel and modules (gcc -g), and
717 is needed if you intend to use kernel crashdump or binary object
718 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
1da177e4
LT
719 Say Y here only if you plan to debug the kernel.
720
721 If unsure, say N.
722
d6f4ceb7
AK
723config DEBUG_INFO_REDUCED
724 bool "Reduce debugging information"
725 depends on DEBUG_INFO
726 help
727 If you say Y here gcc is instructed to generate less debugging
728 information for structure types. This means that tools that
729 need full debugging information (like kgdb or systemtap) won't
730 be happy. But if you merely need debugging information to
731 resolve line numbers there is no loss. Advantage is that
732 build directory object sizes shrink dramatically over a full
733 DEBUG_INFO build and compile times are reduced too.
734 Only works with newer gcc versions.
735
a241ec65
PM
736config DEBUG_VM
737 bool "Debug VM"
738 depends on DEBUG_KERNEL
739 help
13e7444b
NP
740 Enable this to turn on extended checks in the virtual-memory system
741 that may impact performance.
a241ec65
PM
742
743 If unsure, say N.
744
ed8ea815
ML
745config DEBUG_VM_RB
746 bool "Debug VM red-black trees"
747 depends on DEBUG_VM
748 help
749 Enable this to turn on more extended checks in the virtual-memory
750 system that may impact performance.
751
752 If unsure, say N.
753
59ea7463
JS
754config DEBUG_VIRTUAL
755 bool "Debug VM translations"
756 depends on DEBUG_KERNEL && X86
757 help
758 Enable some costly sanity checks in virtual to page code. This can
759 catch mistakes with virt_to_page() and friends.
760
761 If unsure, say N.
762
8feae131
DH
763config DEBUG_NOMMU_REGIONS
764 bool "Debug the global anon/private NOMMU mapping region tree"
765 depends on DEBUG_KERNEL && !MMU
766 help
767 This option causes the global tree of anonymous and private mapping
768 regions to be regularly checked for invalid topology.
769
ad775f5a
DH
770config DEBUG_WRITECOUNT
771 bool "Debug filesystem writers count"
772 depends on DEBUG_KERNEL
773 help
774 Enable this to catch wrong use of the writers count in struct
775 vfsmount. This will increase the size of each file struct by
776 32 bits.
777
778 If unsure, say N.
779
6b74ab97 780config DEBUG_MEMORY_INIT
6a108a14
DR
781 bool "Debug memory initialisation" if EXPERT
782 default !EXPERT
6b74ab97
MG
783 help
784 Enable this for additional checks during memory initialisation.
785 The sanity checks verify aspects of the VM such as the memory model
786 and other information provided by the architecture. Verbose
787 information will be printed at KERN_DEBUG loglevel depending
788 on the mminit_loglevel= command-line option.
789
790 If unsure, say Y
791
199a9afc
DJ
792config DEBUG_LIST
793 bool "Debug linked list manipulation"
794 depends on DEBUG_KERNEL
795 help
796 Enable this to turn on extended checks in the linked-list
797 walking routines.
798
799 If unsure, say N.
800
6d411e6c
AB
801config TEST_LIST_SORT
802 bool "Linked list sorting test"
803 depends on DEBUG_KERNEL
804 help
805 Enable this to turn on 'list_sort()' function test. This test is
806 executed only once during system boot, so affects only boot time.
807
808 If unsure, say N.
809
d6ec0842
JA
810config DEBUG_SG
811 bool "Debug SG table operations"
812 depends on DEBUG_KERNEL
813 help
814 Enable this to turn on checks on scatter-gather tables. This can
815 help find problems with drivers that do not properly initialize
816 their sg tables.
817
818 If unsure, say N.
819
1b2439db
AV
820config DEBUG_NOTIFIERS
821 bool "Debug notifier call chains"
822 depends on DEBUG_KERNEL
823 help
824 Enable this to turn on sanity checking for notifier call chains.
825 This is most useful for kernel developers to make sure that
826 modules properly unregister themselves from notifier chains.
827 This is a relatively cheap check but if you care about maximum
828 performance, say N.
829
e0e81739
DH
830config DEBUG_CREDENTIALS
831 bool "Debug credential management"
832 depends on DEBUG_KERNEL
833 help
834 Enable this to turn on some debug checking for credential
835 management. The additional code keeps track of the number of
836 pointers from task_structs to any given cred struct, and checks to
837 see that this number never exceeds the usage count of the cred
838 struct.
839
840 Furthermore, if SELinux is enabled, this also checks that the
841 security pointer in the cred struct is never seen to be invalid.
842
843 If unsure, say N.
844
64dec40d
JM
845#
846# Select this config option from the architecture Kconfig, if it
52288b66 847# is preferred to always offer frame pointers as a config
64dec40d
JM
848# option on the architecture (regardless of KERNEL_DEBUG):
849#
850config ARCH_WANT_FRAME_POINTERS
851 bool
852 help
853
1da177e4
LT
854config FRAME_POINTER
855 bool "Compile the kernel with frame pointers"
b920de1b 856 depends on DEBUG_KERNEL && \
73020415 857 (CRIS || M68K || FRV || UML || \
79f83c02 858 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
da4276b8
IM
859 ARCH_WANT_FRAME_POINTERS
860 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
861 help
862 If you say Y here the resulting kernel image will be slightly
863 larger and slower, but it gives very useful debugging information
864 in case of kernel bugs. (precise oopses/stacktraces/warnings)
1da177e4 865
bfe8df3d
RD
866config BOOT_PRINTK_DELAY
867 bool "Delay each boot printk message by N milliseconds"
868 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
869 help
870 This build option allows you to read kernel boot messages
871 by inserting a short delay after each one. The delay is
872 specified in milliseconds on the kernel command line,
873 using "boot_delay=N".
874
875 It is likely that you would also need to use "lpj=M" to preset
876 the "loops per jiffie" value.
877 See a previous boot log for the "lpj" value to use for your
878 system, and then set "lpj=M" before setting "boot_delay=N".
879 NOTE: Using this option may adversely affect SMP systems.
880 I.e., processors other than the first one may not boot up.
8edbb83e 881 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
bfe8df3d
RD
882 what it believes to be lockup conditions.
883
2f03e3ca
DH
884menu "RCU Debugging"
885
886config PROVE_RCU
887 bool "RCU debugging: prove RCU correctness"
888 depends on PROVE_LOCKING
889 default n
890 help
891 This feature enables lockdep extensions that check for correct
892 use of RCU APIs. This is currently under development. Say Y
893 if you want to debug RCU usage or help work on the PROVE_RCU
894 feature.
895
896 Say N if you are unsure.
897
898config PROVE_RCU_REPEATEDLY
899 bool "RCU debugging: don't disable PROVE_RCU on first splat"
900 depends on PROVE_RCU
901 default n
902 help
903 By itself, PROVE_RCU will disable checking upon issuing the
904 first warning (or "splat"). This feature prevents such
905 disabling, allowing multiple RCU-lockdep warnings to be printed
906 on a single reboot.
907
908 Say Y to allow multiple RCU-lockdep warnings per boot.
909
910 Say N if you are unsure.
911
912config PROVE_RCU_DELAY
913 bool "RCU debugging: preemptible RCU race provocation"
914 depends on DEBUG_KERNEL && PREEMPT_RCU
915 default n
916 help
917 There is a class of races that involve an unlikely preemption
918 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
919 been set to INT_MIN. This feature inserts a delay at that
920 point to increase the probability of these races.
921
922 Say Y to increase probability of preemption of __rcu_read_unlock().
923
924 Say N if you are unsure.
925
926config SPARSE_RCU_POINTER
927 bool "RCU debugging: sparse-based checks for pointer usage"
928 default n
929 help
930 This feature enables the __rcu sparse annotation for
931 RCU-protected pointers. This annotation will cause sparse
932 to flag any non-RCU used of annotated pointers. This can be
933 helpful when debugging RCU usage. Please note that this feature
934 is not intended to enforce code cleanliness; it is instead merely
935 a debugging aid.
936
937 Say Y to make sparse flag questionable use of RCU-protected pointers
938
939 Say N if you are unsure.
940
a241ec65
PM
941config RCU_TORTURE_TEST
942 tristate "torture tests for RCU"
943 depends on DEBUG_KERNEL
944 default n
945 help
946 This option provides a kernel module that runs torture tests
947 on the RCU infrastructure. The kernel module may be built
948 after the fact on the running kernel to be tested, if desired.
949
31a72bce
PM
950 Say Y here if you want RCU torture tests to be built into
951 the kernel.
a241ec65
PM
952 Say M if you want the RCU torture tests to build as a module.
953 Say N if you are unsure.
8bb31b9d 954
31a72bce
PM
955config RCU_TORTURE_TEST_RUNNABLE
956 bool "torture tests for RCU runnable by default"
957 depends on RCU_TORTURE_TEST = y
958 default n
959 help
960 This option provides a way to build the RCU torture tests
961 directly into the kernel without them starting up at boot
962 time. You can use /proc/sys/kernel/rcutorture_runnable
963 to manually override this setting. This /proc file is
964 available only when the RCU torture tests have been built
965 into the kernel.
966
967 Say Y here if you want the RCU torture tests to start during
968 boot (you probably don't).
969 Say N here if you want the RCU torture tests to start only
970 after being manually enabled via /proc.
971
b163760e
PM
972config RCU_CPU_STALL_TIMEOUT
973 int "RCU CPU stall timeout in seconds"
6bfc09e2 974 depends on RCU_STALL_COMMON
b163760e 975 range 3 300
c896054f 976 default 21
b163760e
PM
977 help
978 If a given RCU grace period extends more than the specified
979 number of seconds, a CPU stall warning is printed. If the
980 RCU grace period persists, additional CPU stall warnings are
981 printed at more widely spaced intervals.
982
1ed509a2
PM
983config RCU_CPU_STALL_VERBOSE
984 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
a00e0d71 985 depends on TREE_PREEMPT_RCU
55ec936f 986 default y
1ed509a2
PM
987 help
988 This option causes RCU to printk detailed per-task information
989 for any tasks that are stalling the current RCU grace period.
67182ae1
PM
990
991 Say N if you are unsure.
992
1ed509a2
PM
993 Say Y if you want to enable such checks.
994
a858af28
PM
995config RCU_CPU_STALL_INFO
996 bool "Print additional diagnostics on RCU CPU stall"
997 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
998 default n
999 help
1000 For each stalled CPU that is aware of the current RCU grace
1001 period, print out additional per-CPU diagnostic information
1002 regarding scheduling-clock ticks, idle state, and,
1003 for RCU_FAST_NO_HZ kernels, idle-entry state.
1004
1005 Say N if you are unsure.
1006
1007 Say Y if you want to enable such diagnostics.
1008
5c8806a0
PM
1009config RCU_TRACE
1010 bool "Enable tracing for RCU"
1011 depends on DEBUG_KERNEL
52494535 1012 select TRACE_CLOCK
5c8806a0
PM
1013 help
1014 This option provides tracing in RCU which presents stats
1015 in debugfs for debugging RCU implementation.
1016
1017 Say Y here if you want to enable RCU tracing
1018 Say N if you are unsure.
1019
2f03e3ca
DH
1020endmenu # "RCU Debugging"
1021
8c1c9356
AM
1022config KPROBES_SANITY_TEST
1023 bool "Kprobes sanity tests"
1024 depends on DEBUG_KERNEL
1025 depends on KPROBES
1026 default n
1027 help
1028 This option provides for testing basic kprobes functionality on
1029 boot. A sample kprobe, jprobe and kretprobe are inserted and
1030 verified for functionality.
1031
1032 Say N if you are unsure.
1033
6dab2778
AV
1034config BACKTRACE_SELF_TEST
1035 tristate "Self test for the backtrace code"
1036 depends on DEBUG_KERNEL
1037 default n
1038 help
1039 This option provides a kernel module that can be used to test
1040 the kernel stack backtrace code. This option is not useful
1041 for distributions or general kernels, but only for kernel
1042 developers working on architecture code.
1043
ad118c54
VN
1044 Note that if you want to also test saved backtraces, you will
1045 have to enable STACKTRACE as well.
1046
6dab2778
AV
1047 Say N if you are unsure.
1048
870d6656
TH
1049config DEBUG_BLOCK_EXT_DEVT
1050 bool "Force extended block device numbers and spread them"
1051 depends on DEBUG_KERNEL
1052 depends on BLOCK
759f8ca3 1053 default n
870d6656 1054 help
0e11e342
TH
1055 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1056 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1057 YOU ARE DOING. Distros, please enable this and fix whatever
1058 is broken.
1059
870d6656
TH
1060 Conventionally, block device numbers are allocated from
1061 predetermined contiguous area. However, extended block area
1062 may introduce non-contiguous block device numbers. This
1063 option forces most block device numbers to be allocated from
1064 the extended space and spreads them to discover kernel or
1065 userland code paths which assume predetermined contiguous
1066 device number allocation.
1067
55dc7db7
TH
1068 Note that turning on this debug option shuffles all the
1069 device numbers for all IDE and SCSI devices including libata
1070 ones, so root partition specified using device number
1071 directly (via rdev or root=MAJ:MIN) won't work anymore.
1072 Textual device names (root=/dev/sdXn) will continue to work.
1073
870d6656
TH
1074 Say N if you are unsure.
1075
7c756e6e
TH
1076config DEBUG_FORCE_WEAK_PER_CPU
1077 bool "Force weak per-cpu definitions"
1078 depends on DEBUG_KERNEL
1079 help
1080 s390 and alpha require percpu variables in modules to be
1081 defined weak to work around addressing range issue which
1082 puts the following two restrictions on percpu variable
1083 definitions.
1084
1085 1. percpu symbols must be unique whether static or not
1086 2. percpu variables can't be defined inside a function
1087
1088 To ensure that generic code follows the above rules, this
1089 option forces all percpu variables to be defined as weak.
1090
44ec7abe
SB
1091config DEBUG_PER_CPU_MAPS
1092 bool "Debug access to per_cpu maps"
1093 depends on DEBUG_KERNEL
1094 depends on SMP
1095 help
1096 Say Y to verify that the per_cpu map being accessed has
1097 been set up. This adds a fair amount of code to kernel memory
1098 and decreases performance.
1099
1100 Say N if unsure.
1101
8bb31b9d
AG
1102config LKDTM
1103 tristate "Linux Kernel Dump Test Tool Module"
0347af4e 1104 depends on DEBUG_FS
fddd9cf8 1105 depends on BLOCK
8bb31b9d
AG
1106 default n
1107 help
1108 This module enables testing of the different dumping mechanisms by
1109 inducing system failures at predefined crash points.
1110 If you don't need it: say N
1111 Choose M here to compile this code as a module. The module will be
1112 called lkdtm.
1113
1114 Documentation on how to use the module can be found in
0347af4e 1115 Documentation/fault-injection/provoke-crashes.txt
6ff1cb35 1116
8d438288
AM
1117config NOTIFIER_ERROR_INJECTION
1118 tristate "Notifier error injection"
1119 depends on DEBUG_KERNEL
1120 select DEBUG_FS
1121 help
e41e85cc 1122 This option provides the ability to inject artificial errors to
8d438288
AM
1123 specified notifier chain callbacks. It is useful to test the error
1124 handling of notifier call chain failures.
1125
1126 Say N if unsure.
1127
c9d221f8
AM
1128config CPU_NOTIFIER_ERROR_INJECT
1129 tristate "CPU notifier error injection module"
f5a9f52e 1130 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
c9d221f8
AM
1131 help
1132 This option provides a kernel module that can be used to test
e41e85cc 1133 the error handling of the cpu notifiers by injecting artificial
f5a9f52e
AM
1134 errors to CPU notifier chain callbacks. It is controlled through
1135 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1136
1137 If the notifier call chain should be failed with some events
1138 notified, write the error code to "actions/<notifier event>/error".
1139
1140 Example: Inject CPU offline error (-1 == -EPERM)
1141
1142 # cd /sys/kernel/debug/notifier-error-inject/cpu
1143 # echo -1 > actions/CPU_DOWN_PREPARE/error
1144 # echo 0 > /sys/devices/system/cpu/cpu1/online
1145 bash: echo: write error: Operation not permitted
c9d221f8
AM
1146
1147 To compile this code as a module, choose M here: the module will
1148 be called cpu-notifier-error-inject.
1149
1150 If unsure, say N.
1151
048b9c35
AM
1152config PM_NOTIFIER_ERROR_INJECT
1153 tristate "PM notifier error injection module"
1154 depends on PM && NOTIFIER_ERROR_INJECTION
1155 default m if PM_DEBUG
1156 help
e41e85cc 1157 This option provides the ability to inject artificial errors to
048b9c35
AM
1158 PM notifier chain callbacks. It is controlled through debugfs
1159 interface /sys/kernel/debug/notifier-error-inject/pm
1160
1161 If the notifier call chain should be failed with some events
1162 notified, write the error code to "actions/<notifier event>/error".
1163
1164 Example: Inject PM suspend error (-12 = -ENOMEM)
1165
1166 # cd /sys/kernel/debug/notifier-error-inject/pm/
1167 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1168 # echo mem > /sys/power/state
1169 bash: echo: write error: Cannot allocate memory
1170
1171 To compile this code as a module, choose M here: the module will
1172 be called pm-notifier-error-inject.
1173
1174 If unsure, say N.
1175
9579f5bd
AM
1176config MEMORY_NOTIFIER_ERROR_INJECT
1177 tristate "Memory hotplug notifier error injection module"
1178 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1179 help
e41e85cc 1180 This option provides the ability to inject artificial errors to
9579f5bd
AM
1181 memory hotplug notifier chain callbacks. It is controlled through
1182 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
1183
1184 If the notifier call chain should be failed with some events
1185 notified, write the error code to "actions/<notifier event>/error".
1186
1187 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
1188
1189 # cd /sys/kernel/debug/notifier-error-inject/memory
1190 # echo -12 > actions/MEM_GOING_OFFLINE/error
1191 # echo offline > /sys/devices/system/memory/memoryXXX/state
1192 bash: echo: write error: Cannot allocate memory
1193
1194 To compile this code as a module, choose M here: the module will
e12a95f4 1195 be called memory-notifier-error-inject.
9579f5bd
AM
1196
1197 If unsure, say N.
1198
d526e85f
BH
1199config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1200 tristate "OF reconfig notifier error injection module"
1201 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
08dfb4dd 1202 help
e41e85cc 1203 This option provides the ability to inject artificial errors to
d526e85f 1204 OF reconfig notifier chain callbacks. It is controlled
08dfb4dd 1205 through debugfs interface under
d526e85f 1206 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
08dfb4dd
AM
1207
1208 If the notifier call chain should be failed with some events
1209 notified, write the error code to "actions/<notifier event>/error".
1210
1211 To compile this code as a module, choose M here: the module will
e12a95f4 1212 be called of-reconfig-notifier-error-inject.
08dfb4dd
AM
1213
1214 If unsure, say N.
1215
6ff1cb35 1216config FAULT_INJECTION
1ab8509a
AM
1217 bool "Fault-injection framework"
1218 depends on DEBUG_KERNEL
329409ae
AM
1219 help
1220 Provide fault-injection framework.
1221 For more details, see Documentation/fault-injection/.
6ff1cb35 1222
8a8b6502 1223config FAILSLAB
1ab8509a
AM
1224 bool "Fault-injection capability for kmalloc"
1225 depends on FAULT_INJECTION
773ff60e 1226 depends on SLAB || SLUB
8a8b6502 1227 help
1ab8509a 1228 Provide fault-injection capability for kmalloc.
8a8b6502 1229
933e312e
AM
1230config FAIL_PAGE_ALLOC
1231 bool "Fault-injection capabilitiy for alloc_pages()"
1ab8509a 1232 depends on FAULT_INJECTION
933e312e 1233 help
1ab8509a 1234 Provide fault-injection capability for alloc_pages().
933e312e 1235
c17bb495 1236config FAIL_MAKE_REQUEST
86327d19 1237 bool "Fault-injection capability for disk IO"
581d4e28 1238 depends on FAULT_INJECTION && BLOCK
c17bb495 1239 help
1ab8509a 1240 Provide fault-injection capability for disk IO.
c17bb495 1241
581d4e28 1242config FAIL_IO_TIMEOUT
f4d01439 1243 bool "Fault-injection capability for faking disk interrupts"
581d4e28
JA
1244 depends on FAULT_INJECTION && BLOCK
1245 help
1246 Provide fault-injection capability on end IO handling. This
1247 will make the block layer "forget" an interrupt as configured,
1248 thus exercising the error handling.
1249
1250 Only works with drivers that use the generic timeout handling,
1251 for others it wont do anything.
1252
1b676f70
PF
1253config FAIL_MMC_REQUEST
1254 bool "Fault-injection capability for MMC IO"
1255 select DEBUG_FS
1256 depends on FAULT_INJECTION && MMC
1257 help
1258 Provide fault-injection capability for MMC IO.
1259 This will make the mmc core return data errors. This is
1260 useful to test the error handling in the mmc block device
1261 and to test how the mmc host driver handles retries from
1262 the block device.
1263
6ff1cb35
AM
1264config FAULT_INJECTION_DEBUG_FS
1265 bool "Debugfs entries for fault-injection capabilities"
1ab8509a 1266 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
6ff1cb35 1267 help
1ab8509a 1268 Enable configuration of fault-injection capabilities via debugfs.
1df49008
AM
1269
1270config FAULT_INJECTION_STACKTRACE_FILTER
1271 bool "stacktrace filter for fault-injection capabilities"
1272 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
6d690dca 1273 depends on !X86_64
1df49008 1274 select STACKTRACE
3c19c4f9 1275 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1df49008
AM
1276 help
1277 Provide stacktrace filter for fault-injection capabilities
267c4025 1278
9745512c
AV
1279config LATENCYTOP
1280 bool "Latency measuring infrastructure"
625fdcaa
RD
1281 depends on HAVE_LATENCYTOP_SUPPORT
1282 depends on DEBUG_KERNEL
1283 depends on STACKTRACE_SUPPORT
1284 depends on PROC_FS
89bace65 1285 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
9745512c
AV
1286 select KALLSYMS
1287 select KALLSYMS_ALL
1288 select STACKTRACE
1289 select SCHEDSTATS
1290 select SCHED_DEBUG
9745512c
AV
1291 help
1292 Enable this option if you want to use the LatencyTOP tool
1293 to find out which userspace is blocking on what kernel operations.
1294
446f24d1
SB
1295config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1296 bool
1297
1298config DEBUG_STRICT_USER_COPY_CHECKS
1299 bool "Strict user copy size checks"
1300 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1301 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1302 help
1303 Enabling this option turns a certain set of sanity checks for user
1304 copy operations into compile time failures.
1305
1306 The copy_from_user() etc checks are there to help test if there
1307 are sufficient security checks on the length argument of
1308 the copy operation, by having gcc prove that the argument is
1309 within bounds.
1310
1311 If unsure, say N.
1312
6a11f75b 1313source mm/Kconfig.debug
16444a8a
ACM
1314source kernel/trace/Kconfig
1315
910a742d
ML
1316config RBTREE_TEST
1317 tristate "Red-Black tree test"
1318 depends on m && DEBUG_KERNEL
1319 help
1320 A benchmark measuring the performance of the rbtree library.
1321 Also includes rbtree invariant checks.
1322
fff3fd8a
ML
1323config INTERVAL_TREE_TEST
1324 tristate "Interval tree test"
1325 depends on m && DEBUG_KERNEL
1326 help
1327 A benchmark measuring the performance of the interval tree library
1328
f212ec4b 1329config PROVIDE_OHCI1394_DMA_INIT
080de8c2 1330 bool "Remote debugging over FireWire early on boot"
f212ec4b
BK
1331 depends on PCI && X86
1332 help
1333 If you want to debug problems which hang or crash the kernel early
1334 on boot and the crashing machine has a FireWire port, you can use
1335 this feature to remotely access the memory of the crashed machine
1336 over FireWire. This employs remote DMA as part of the OHCI1394
1337 specification which is now the standard for FireWire controllers.
1338
1339 With remote DMA, you can monitor the printk buffer remotely using
1340 firescope and access all memory below 4GB using fireproxy from gdb.
1341 Even controlling a kernel debugger is possible using remote DMA.
1342
1343 Usage:
1344
1345 If ohci1394_dma=early is used as boot parameter, it will initialize
1346 all OHCI1394 controllers which are found in the PCI config space.
1347
1348 As all changes to the FireWire bus such as enabling and disabling
1349 devices cause a bus reset and thereby disable remote DMA for all
1350 devices, be sure to have the cable plugged and FireWire enabled on
1351 the debugging host before booting the debug target for debugging.
1352
1353 This code (~1k) is freed after boot. By then, the firewire stack
1354 in charge of the OHCI-1394 controllers should be used instead.
1355
1356 See Documentation/debugging-via-ohci1394.txt for more information.
9745512c 1357
080de8c2
SR
1358config FIREWIRE_OHCI_REMOTE_DMA
1359 bool "Remote debugging over FireWire with firewire-ohci"
1360 depends on FIREWIRE_OHCI
1361 help
1362 This option lets you use the FireWire bus for remote debugging
1363 with help of the firewire-ohci driver. It enables unfiltered
1364 remote DMA in firewire-ohci.
1365 See Documentation/debugging-via-ohci1394.txt for more information.
1366
1367 If unsure, say N.
1368
152de30b 1369config BUILD_DOCSRC
3794f3e8
RD
1370 bool "Build targets in Documentation/ tree"
1371 depends on HEADERS_CHECK
1372 help
1373 This option attempts to build objects from the source files in the
1374 kernel Documentation/ tree.
1375
1376 Say N if you are unsure.
1377
e9d376f0 1378config DYNAMIC_DEBUG
86151fdf 1379 bool "Enable dynamic printk() support"
346e15be
JB
1380 default n
1381 depends on PRINTK
86151fdf 1382 depends on DEBUG_FS
346e15be
JB
1383 help
1384
1385 Compiles debug level messages into the kernel, which would not
1386 otherwise be available at runtime. These messages can then be
86151fdf
JB
1387 enabled/disabled based on various levels of scope - per source file,
1388 function, module, format string, and line number. This mechanism
29e36c9f
JC
1389 implicitly compiles in all pr_debug() and dev_dbg() calls, which
1390 enlarges the kernel text size by about 2%.
1391
1392 If a source file is compiled with DEBUG flag set, any
1393 pr_debug() calls in it are enabled by default, but can be
1394 disabled at runtime as below. Note that DEBUG flag is
1395 turned on by many CONFIG_*DEBUG* options.
346e15be
JB
1396
1397 Usage:
1398
2b2f68b5 1399 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
86151fdf
JB
1400 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1401 filesystem must first be mounted before making use of this feature.
2b2f68b5 1402 We refer the control file as: <debugfs>/dynamic_debug/control. This
86151fdf
JB
1403 file contains a list of the debug statements that can be enabled. The
1404 format for each line of the file is:
346e15be 1405
86151fdf 1406 filename:lineno [module]function flags format
346e15be 1407
86151fdf
JB
1408 filename : source file of the debug statement
1409 lineno : line number of the debug statement
1410 module : module that contains the debug statement
1411 function : function that contains the debug statement
29e36c9f 1412 flags : '=p' means the line is turned 'on' for printing
86151fdf 1413 format : the format used for the debug statement
346e15be
JB
1414
1415 From a live system:
1416
2b2f68b5 1417 nullarbor:~ # cat <debugfs>/dynamic_debug/control
86151fdf 1418 # filename:lineno [module]function flags format
29e36c9f
JC
1419 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1420 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1421 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
346e15be 1422
86151fdf 1423 Example usage:
346e15be 1424
86151fdf
JB
1425 // enable the message at line 1603 of file svcsock.c
1426 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
2b2f68b5 1427 <debugfs>/dynamic_debug/control
346e15be 1428
86151fdf
JB
1429 // enable all the messages in file svcsock.c
1430 nullarbor:~ # echo -n 'file svcsock.c +p' >
2b2f68b5 1431 <debugfs>/dynamic_debug/control
346e15be 1432
86151fdf
JB
1433 // enable all the messages in the NFS server module
1434 nullarbor:~ # echo -n 'module nfsd +p' >
2b2f68b5 1435 <debugfs>/dynamic_debug/control
346e15be 1436
86151fdf
JB
1437 // enable all 12 messages in the function svc_process()
1438 nullarbor:~ # echo -n 'func svc_process +p' >
2b2f68b5 1439 <debugfs>/dynamic_debug/control
346e15be 1440
86151fdf
JB
1441 // disable all 12 messages in the function svc_process()
1442 nullarbor:~ # echo -n 'func svc_process -p' >
2b2f68b5 1443 <debugfs>/dynamic_debug/control
346e15be 1444
86151fdf 1445 See Documentation/dynamic-debug-howto.txt for additional information.
346e15be 1446
5ee00bd4
JR
1447config DMA_API_DEBUG
1448 bool "Enable debugging of DMA-API usage"
1449 depends on HAVE_DMA_API_DEBUG
1450 help
1451 Enable this option to debug the use of the DMA API by device drivers.
1452 With this option you will be able to detect common bugs in device
1453 drivers like double-freeing of DMA mappings or freeing mappings that
1454 were never allocated.
1455 This option causes a performance degredation. Use only if you want
1456 to debug device drivers. If unsure, say N.
346e15be 1457
86a89380
LB
1458config ATOMIC64_SELFTEST
1459 bool "Perform an atomic64_t self-test at boot"
1460 help
1461 Enable this option to test the atomic64_t functions at boot.
1462
1463 If unsure, say N.
1464
400fb7f6
DW
1465config ASYNC_RAID6_TEST
1466 tristate "Self test for hardware accelerated raid6 recovery"
1467 depends on ASYNC_RAID6_RECOV
1468 select ASYNC_MEMCPY
1469 ---help---
1470 This is a one-shot self test that permutes through the
1471 recovery of all the possible two disk failure scenarios for a
1472 N-disk array. Recovery is performed with the asynchronous
1473 raid6 recovery routines, and will optionally use an offload
1474 engine if one is available.
1475
1476 If unsure, say N.
1477
267c4025 1478source "samples/Kconfig"
dc7d5527
JW
1479
1480source "lib/Kconfig.kgdb"
0a4af3b0
PE
1481
1482source "lib/Kconfig.kmemcheck"
33ee3b2e 1483
16c7fa05
AS
1484config TEST_STRING_HELPERS
1485 tristate "Test functions located in the string_helpers module at runtime"
1486
33ee3b2e
AD
1487config TEST_KSTRTOX
1488 tristate "Test kstrto*() family of functions at runtime"