]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blame - lib/Kconfig.debug
lib/parser.c: avoid overflow in match_number()
[mirror_ubuntu-bionic-kernel.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
MW
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.
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
4a7863cc 199 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
d314d74c 200 !HAVE_NMI_WATCHDOG
8446f1d3 201
fef2c9bc
DZ
202config BOOTPARAM_HARDLOCKUP_PANIC
203 bool "Panic (Reboot) On Hard Lockups"
204 depends on LOCKUP_DETECTOR
205 help
206 Say Y here to enable the kernel to panic on "hard lockups",
207 which are bugs that cause the kernel to loop in kernel
5f329089
FLVC
208 mode with interrupts disabled for more than 10 seconds (configurable
209 using the watchdog_thresh sysctl).
fef2c9bc
DZ
210
211 Say N if unsure.
212
213config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
214 int
215 depends on LOCKUP_DETECTOR
216 range 0 1
217 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
218 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
219
9c44bc03
IM
220config BOOTPARAM_SOFTLOCKUP_PANIC
221 bool "Panic (Reboot) On Soft Lockups"
89d7ce2a 222 depends on LOCKUP_DETECTOR
9c44bc03
IM
223 help
224 Say Y here to enable the kernel to panic on "soft lockups",
225 which are bugs that cause the kernel to loop in kernel
5f329089
FLVC
226 mode for more than 20 seconds (configurable using the watchdog_thresh
227 sysctl), without giving other tasks a chance to run.
9c44bc03
IM
228
229 The panic can be used in combination with panic_timeout,
230 to cause the system to reboot automatically after a
231 lockup has been detected. This feature is useful for
232 high-availability systems that have uptime guarantees and
233 where a lockup must be resolved ASAP.
234
235 Say N if unsure.
236
237config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
238 int
e16bb1d7 239 depends on LOCKUP_DETECTOR
9c44bc03
IM
240 range 0 1
241 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
242 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
243
2a01bb38
KM
244config PANIC_ON_OOPS
245 bool "Panic on Oops" if EXPERT
246 default n
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
3bba00d7
CM
452config DEBUG_KMEMLEAK
453 bool "Kernel memory leak detector"
029aeff5 454 depends on DEBUG_KERNEL && EXPERIMENTAL && \
8c2c3df3
CM
455 (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || \
456 MICROBLAZE || TILE || ARM64)
dfcc3e6a 457
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
632ee200
PM
607config PROVE_RCU
608 bool "RCU debugging: prove RCU correctness"
609 depends on PROVE_LOCKING
610 default n
611 help
612 This feature enables lockdep extensions that check for correct
613 use of RCU APIs. This is currently under development. Say Y
614 if you want to debug RCU usage or help work on the PROVE_RCU
615 feature.
616
617 Say N if you are unsure.
618
2b3fc35f
LJ
619config PROVE_RCU_REPEATEDLY
620 bool "RCU debugging: don't disable PROVE_RCU on first splat"
621 depends on PROVE_RCU
622 default n
623 help
624 By itself, PROVE_RCU will disable checking upon issuing the
625 first warning (or "splat"). This feature prevents such
626 disabling, allowing multiple RCU-lockdep warnings to be printed
627 on a single reboot.
628
2dfbf4df
PM
629 Say Y to allow multiple RCU-lockdep warnings per boot.
630
631 Say N if you are unsure.
632
e3ebfb96
PM
633config PROVE_RCU_DELAY
634 bool "RCU debugging: preemptible RCU race provocation"
635 depends on DEBUG_KERNEL && PREEMPT_RCU
636 default n
637 help
638 There is a class of races that involve an unlikely preemption
639 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
640 been set to INT_MIN. This feature inserts a delay at that
641 point to increase the probability of these races.
642
643 Say Y to increase probability of preemption of __rcu_read_unlock().
644
645 Say N if you are unsure.
646
ca5ecddf
PM
647config SPARSE_RCU_POINTER
648 bool "RCU debugging: sparse-based checks for pointer usage"
649 default n
650 help
651 This feature enables the __rcu sparse annotation for
652 RCU-protected pointers. This annotation will cause sparse
653 to flag any non-RCU used of annotated pointers. This can be
654 helpful when debugging RCU usage. Please note that this feature
655 is not intended to enforce code cleanliness; it is instead merely
656 a debugging aid.
657
658 Say Y to make sparse flag questionable use of RCU-protected pointers
659
2b3fc35f
LJ
660 Say N if you are unsure.
661
4d9f34ad
IM
662config LOCKDEP
663 bool
517e7aa5 664 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad 665 select STACKTRACE
79aac889 666 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
4d9f34ad
IM
667 select KALLSYMS
668 select KALLSYMS_ALL
669
f20786ff 670config LOCK_STAT
fdfb870f 671 bool "Lock usage statistics"
f20786ff
PZ
672 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
673 select LOCKDEP
674 select DEBUG_SPINLOCK
675 select DEBUG_MUTEXES
676 select DEBUG_LOCK_ALLOC
677 default n
678 help
679 This feature enables tracking lock contention points
680
a560aa48
PZ
681 For more details, see Documentation/lockstat.txt
682
dd8b1cf6
FW
683 This also enables lock events required by "perf lock",
684 subcommand of perf.
685 If you want to use "perf lock", you also need to turn on
686 CONFIG_EVENT_TRACING.
84c6f88f
HM
687
688 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
dd8b1cf6 689 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
84c6f88f 690
4d9f34ad
IM
691config DEBUG_LOCKDEP
692 bool "Lock dependency engine debugging"
517e7aa5 693 depends on DEBUG_KERNEL && LOCKDEP
4d9f34ad
IM
694 help
695 If you say Y here, the lock dependency engine will do
696 additional runtime checks to debug itself, at the price
697 of more runtime overhead.
698
699config TRACE_IRQFLAGS
700 bool
46b93b74
SR
701 help
702 Enables hooks to interrupt enabling and disabling for
703 either tracing or lock debugging.
4d9f34ad 704
d902db1e
FW
705config DEBUG_ATOMIC_SLEEP
706 bool "Sleep inside atomic section checking"
e8f7c70f 707 select PREEMPT_COUNT
1da177e4
LT
708 depends on DEBUG_KERNEL
709 help
710 If you say Y here, various routines which may sleep will become very
d902db1e
FW
711 noisy if they are called inside atomic sections: when a spinlock is
712 held, inside an rcu read side critical section, inside preempt disabled
713 sections, inside an interrupt, etc...
1da177e4 714
cae2ed9a
IM
715config DEBUG_LOCKING_API_SELFTESTS
716 bool "Locking API boot-time self-tests"
717 depends on DEBUG_KERNEL
718 help
719 Say Y here if you want the kernel to run a short self-test during
720 bootup. The self-test checks whether common types of locking bugs
721 are detected by debugging mechanisms or not. (if you disable
722 lock debugging then those bugs wont be detected of course.)
723 The following locking APIs are covered: spinlocks, rwlocks,
724 mutexes and rwsems.
725
8637c099
IM
726config STACKTRACE
727 bool
728 depends on STACKTRACE_SUPPORT
729
5ca43f6c
SB
730config DEBUG_STACK_USAGE
731 bool "Stack utilization instrumentation"
e9c31b32 732 depends on DEBUG_KERNEL && !IA64 && !PARISC
5ca43f6c
SB
733 help
734 Enables the display of the minimum amount of free stack which each
735 task has ever had available in the sysrq-T and sysrq-P debug output.
736
737 This option will slow down process creation somewhat.
738
1da177e4
LT
739config DEBUG_KOBJECT
740 bool "kobject debugging"
741 depends on DEBUG_KERNEL
742 help
743 If you say Y here, some extra kobject debugging messages will be sent
744 to the syslog.
745
746config DEBUG_HIGHMEM
747 bool "Highmem debugging"
748 depends on DEBUG_KERNEL && HIGHMEM
749 help
750 This options enables addition error checking for high memory systems.
751 Disable for production systems.
752
753config DEBUG_BUGVERBOSE
6a108a14 754 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
c8538a7a 755 depends on BUG
b920de1b 756 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
8c2c3df3
CM
757 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || \
758 TILE || ARM64
8420e7ef 759 default y
1da177e4
LT
760 help
761 Say Y here to make BUG() panics output the file name and line number
762 of the BUG call as well as the EIP and oops trace. This aids
763 debugging but costs about 70-100K of memory.
764
765config DEBUG_INFO
766 bool "Compile the kernel with debug info"
767 depends on DEBUG_KERNEL
768 help
769 If you say Y here the resulting kernel image will include
770 debugging info resulting in a larger kernel image.
b72e53f8
AD
771 This adds debug symbols to the kernel and modules (gcc -g), and
772 is needed if you intend to use kernel crashdump or binary object
773 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
1da177e4
LT
774 Say Y here only if you plan to debug the kernel.
775
776 If unsure, say N.
777
d6f4ceb7
AK
778config DEBUG_INFO_REDUCED
779 bool "Reduce debugging information"
780 depends on DEBUG_INFO
781 help
782 If you say Y here gcc is instructed to generate less debugging
783 information for structure types. This means that tools that
784 need full debugging information (like kgdb or systemtap) won't
785 be happy. But if you merely need debugging information to
786 resolve line numbers there is no loss. Advantage is that
787 build directory object sizes shrink dramatically over a full
788 DEBUG_INFO build and compile times are reduced too.
789 Only works with newer gcc versions.
790
a241ec65
PM
791config DEBUG_VM
792 bool "Debug VM"
793 depends on DEBUG_KERNEL
794 help
13e7444b
NP
795 Enable this to turn on extended checks in the virtual-memory system
796 that may impact performance.
a241ec65
PM
797
798 If unsure, say N.
799
59ea7463
JS
800config DEBUG_VIRTUAL
801 bool "Debug VM translations"
802 depends on DEBUG_KERNEL && X86
803 help
804 Enable some costly sanity checks in virtual to page code. This can
805 catch mistakes with virt_to_page() and friends.
806
807 If unsure, say N.
808
8feae131
DH
809config DEBUG_NOMMU_REGIONS
810 bool "Debug the global anon/private NOMMU mapping region tree"
811 depends on DEBUG_KERNEL && !MMU
812 help
813 This option causes the global tree of anonymous and private mapping
814 regions to be regularly checked for invalid topology.
815
ad775f5a
DH
816config DEBUG_WRITECOUNT
817 bool "Debug filesystem writers count"
818 depends on DEBUG_KERNEL
819 help
820 Enable this to catch wrong use of the writers count in struct
821 vfsmount. This will increase the size of each file struct by
822 32 bits.
823
824 If unsure, say N.
825
6b74ab97 826config DEBUG_MEMORY_INIT
6a108a14
DR
827 bool "Debug memory initialisation" if EXPERT
828 default !EXPERT
6b74ab97
MG
829 help
830 Enable this for additional checks during memory initialisation.
831 The sanity checks verify aspects of the VM such as the memory model
832 and other information provided by the architecture. Verbose
833 information will be printed at KERN_DEBUG loglevel depending
834 on the mminit_loglevel= command-line option.
835
836 If unsure, say Y
837
199a9afc
DJ
838config DEBUG_LIST
839 bool "Debug linked list manipulation"
840 depends on DEBUG_KERNEL
841 help
842 Enable this to turn on extended checks in the linked-list
843 walking routines.
844
845 If unsure, say N.
846
6d411e6c
AB
847config TEST_LIST_SORT
848 bool "Linked list sorting test"
849 depends on DEBUG_KERNEL
850 help
851 Enable this to turn on 'list_sort()' function test. This test is
852 executed only once during system boot, so affects only boot time.
853
854 If unsure, say N.
855
d6ec0842
JA
856config DEBUG_SG
857 bool "Debug SG table operations"
858 depends on DEBUG_KERNEL
859 help
860 Enable this to turn on checks on scatter-gather tables. This can
861 help find problems with drivers that do not properly initialize
862 their sg tables.
863
864 If unsure, say N.
865
1b2439db
AV
866config DEBUG_NOTIFIERS
867 bool "Debug notifier call chains"
868 depends on DEBUG_KERNEL
869 help
870 Enable this to turn on sanity checking for notifier call chains.
871 This is most useful for kernel developers to make sure that
872 modules properly unregister themselves from notifier chains.
873 This is a relatively cheap check but if you care about maximum
874 performance, say N.
875
e0e81739
DH
876config DEBUG_CREDENTIALS
877 bool "Debug credential management"
878 depends on DEBUG_KERNEL
879 help
880 Enable this to turn on some debug checking for credential
881 management. The additional code keeps track of the number of
882 pointers from task_structs to any given cred struct, and checks to
883 see that this number never exceeds the usage count of the cred
884 struct.
885
886 Furthermore, if SELinux is enabled, this also checks that the
887 security pointer in the cred struct is never seen to be invalid.
888
889 If unsure, say N.
890
64dec40d
JM
891#
892# Select this config option from the architecture Kconfig, if it
52288b66 893# is preferred to always offer frame pointers as a config
64dec40d
JM
894# option on the architecture (regardless of KERNEL_DEBUG):
895#
896config ARCH_WANT_FRAME_POINTERS
897 bool
898 help
899
1da177e4
LT
900config FRAME_POINTER
901 bool "Compile the kernel with frame pointers"
b920de1b 902 depends on DEBUG_KERNEL && \
73020415 903 (CRIS || M68K || FRV || UML || \
da4276b8
IM
904 AVR32 || SUPERH || BLACKFIN || MN10300) || \
905 ARCH_WANT_FRAME_POINTERS
906 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
907 help
908 If you say Y here the resulting kernel image will be slightly
909 larger and slower, but it gives very useful debugging information
910 in case of kernel bugs. (precise oopses/stacktraces/warnings)
1da177e4 911
bfe8df3d
RD
912config BOOT_PRINTK_DELAY
913 bool "Delay each boot printk message by N milliseconds"
914 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
915 help
916 This build option allows you to read kernel boot messages
917 by inserting a short delay after each one. The delay is
918 specified in milliseconds on the kernel command line,
919 using "boot_delay=N".
920
921 It is likely that you would also need to use "lpj=M" to preset
922 the "loops per jiffie" value.
923 See a previous boot log for the "lpj" value to use for your
924 system, and then set "lpj=M" before setting "boot_delay=N".
925 NOTE: Using this option may adversely affect SMP systems.
926 I.e., processors other than the first one may not boot up.
8edbb83e 927 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
bfe8df3d
RD
928 what it believes to be lockup conditions.
929
a241ec65
PM
930config RCU_TORTURE_TEST
931 tristate "torture tests for RCU"
932 depends on DEBUG_KERNEL
933 default n
934 help
935 This option provides a kernel module that runs torture tests
936 on the RCU infrastructure. The kernel module may be built
937 after the fact on the running kernel to be tested, if desired.
938
31a72bce
PM
939 Say Y here if you want RCU torture tests to be built into
940 the kernel.
a241ec65
PM
941 Say M if you want the RCU torture tests to build as a module.
942 Say N if you are unsure.
8bb31b9d 943
31a72bce
PM
944config RCU_TORTURE_TEST_RUNNABLE
945 bool "torture tests for RCU runnable by default"
946 depends on RCU_TORTURE_TEST = y
947 default n
948 help
949 This option provides a way to build the RCU torture tests
950 directly into the kernel without them starting up at boot
951 time. You can use /proc/sys/kernel/rcutorture_runnable
952 to manually override this setting. This /proc file is
953 available only when the RCU torture tests have been built
954 into the kernel.
955
956 Say Y here if you want the RCU torture tests to start during
957 boot (you probably don't).
958 Say N here if you want the RCU torture tests to start only
959 after being manually enabled via /proc.
960
b163760e
PM
961config RCU_CPU_STALL_TIMEOUT
962 int "RCU CPU stall timeout in seconds"
a00e0d71 963 depends on TREE_RCU || TREE_PREEMPT_RCU
b163760e
PM
964 range 3 300
965 default 60
966 help
967 If a given RCU grace period extends more than the specified
968 number of seconds, a CPU stall warning is printed. If the
969 RCU grace period persists, additional CPU stall warnings are
970 printed at more widely spaced intervals.
971
1ed509a2
PM
972config RCU_CPU_STALL_VERBOSE
973 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
a00e0d71 974 depends on TREE_PREEMPT_RCU
55ec936f 975 default y
1ed509a2
PM
976 help
977 This option causes RCU to printk detailed per-task information
978 for any tasks that are stalling the current RCU grace period.
67182ae1
PM
979
980 Say N if you are unsure.
981
1ed509a2
PM
982 Say Y if you want to enable such checks.
983
a858af28
PM
984config RCU_CPU_STALL_INFO
985 bool "Print additional diagnostics on RCU CPU stall"
986 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
987 default n
988 help
989 For each stalled CPU that is aware of the current RCU grace
990 period, print out additional per-CPU diagnostic information
991 regarding scheduling-clock ticks, idle state, and,
992 for RCU_FAST_NO_HZ kernels, idle-entry state.
993
994 Say N if you are unsure.
995
996 Say Y if you want to enable such diagnostics.
997
5c8806a0
PM
998config RCU_TRACE
999 bool "Enable tracing for RCU"
1000 depends on DEBUG_KERNEL
1001 help
1002 This option provides tracing in RCU which presents stats
1003 in debugfs for debugging RCU implementation.
1004
1005 Say Y here if you want to enable RCU tracing
1006 Say N if you are unsure.
1007
8c1c9356
AM
1008config KPROBES_SANITY_TEST
1009 bool "Kprobes sanity tests"
1010 depends on DEBUG_KERNEL
1011 depends on KPROBES
1012 default n
1013 help
1014 This option provides for testing basic kprobes functionality on
1015 boot. A sample kprobe, jprobe and kretprobe are inserted and
1016 verified for functionality.
1017
1018 Say N if you are unsure.
1019
6dab2778
AV
1020config BACKTRACE_SELF_TEST
1021 tristate "Self test for the backtrace code"
1022 depends on DEBUG_KERNEL
1023 default n
1024 help
1025 This option provides a kernel module that can be used to test
1026 the kernel stack backtrace code. This option is not useful
1027 for distributions or general kernels, but only for kernel
1028 developers working on architecture code.
1029
ad118c54
VN
1030 Note that if you want to also test saved backtraces, you will
1031 have to enable STACKTRACE as well.
1032
6dab2778
AV
1033 Say N if you are unsure.
1034
870d6656
TH
1035config DEBUG_BLOCK_EXT_DEVT
1036 bool "Force extended block device numbers and spread them"
1037 depends on DEBUG_KERNEL
1038 depends on BLOCK
759f8ca3 1039 default n
870d6656 1040 help
0e11e342
TH
1041 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1042 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1043 YOU ARE DOING. Distros, please enable this and fix whatever
1044 is broken.
1045
870d6656
TH
1046 Conventionally, block device numbers are allocated from
1047 predetermined contiguous area. However, extended block area
1048 may introduce non-contiguous block device numbers. This
1049 option forces most block device numbers to be allocated from
1050 the extended space and spreads them to discover kernel or
1051 userland code paths which assume predetermined contiguous
1052 device number allocation.
1053
55dc7db7
TH
1054 Note that turning on this debug option shuffles all the
1055 device numbers for all IDE and SCSI devices including libata
1056 ones, so root partition specified using device number
1057 directly (via rdev or root=MAJ:MIN) won't work anymore.
1058 Textual device names (root=/dev/sdXn) will continue to work.
1059
870d6656
TH
1060 Say N if you are unsure.
1061
7c756e6e
TH
1062config DEBUG_FORCE_WEAK_PER_CPU
1063 bool "Force weak per-cpu definitions"
1064 depends on DEBUG_KERNEL
1065 help
1066 s390 and alpha require percpu variables in modules to be
1067 defined weak to work around addressing range issue which
1068 puts the following two restrictions on percpu variable
1069 definitions.
1070
1071 1. percpu symbols must be unique whether static or not
1072 2. percpu variables can't be defined inside a function
1073
1074 To ensure that generic code follows the above rules, this
1075 option forces all percpu variables to be defined as weak.
1076
44ec7abe
SB
1077config DEBUG_PER_CPU_MAPS
1078 bool "Debug access to per_cpu maps"
1079 depends on DEBUG_KERNEL
1080 depends on SMP
1081 help
1082 Say Y to verify that the per_cpu map being accessed has
1083 been set up. This adds a fair amount of code to kernel memory
1084 and decreases performance.
1085
1086 Say N if unsure.
1087
8bb31b9d
AG
1088config LKDTM
1089 tristate "Linux Kernel Dump Test Tool Module"
0347af4e 1090 depends on DEBUG_FS
fddd9cf8 1091 depends on BLOCK
8bb31b9d
AG
1092 default n
1093 help
1094 This module enables testing of the different dumping mechanisms by
1095 inducing system failures at predefined crash points.
1096 If you don't need it: say N
1097 Choose M here to compile this code as a module. The module will be
1098 called lkdtm.
1099
1100 Documentation on how to use the module can be found in
0347af4e 1101 Documentation/fault-injection/provoke-crashes.txt
6ff1cb35 1102
8d438288
AM
1103config NOTIFIER_ERROR_INJECTION
1104 tristate "Notifier error injection"
1105 depends on DEBUG_KERNEL
1106 select DEBUG_FS
1107 help
1108 This option provides the ability to inject artifical errors to
1109 specified notifier chain callbacks. It is useful to test the error
1110 handling of notifier call chain failures.
1111
1112 Say N if unsure.
1113
c9d221f8
AM
1114config CPU_NOTIFIER_ERROR_INJECT
1115 tristate "CPU notifier error injection module"
f5a9f52e 1116 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
c9d221f8
AM
1117 help
1118 This option provides a kernel module that can be used to test
f5a9f52e
AM
1119 the error handling of the cpu notifiers by injecting artifical
1120 errors to CPU notifier chain callbacks. It is controlled through
1121 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1122
1123 If the notifier call chain should be failed with some events
1124 notified, write the error code to "actions/<notifier event>/error".
1125
1126 Example: Inject CPU offline error (-1 == -EPERM)
1127
1128 # cd /sys/kernel/debug/notifier-error-inject/cpu
1129 # echo -1 > actions/CPU_DOWN_PREPARE/error
1130 # echo 0 > /sys/devices/system/cpu/cpu1/online
1131 bash: echo: write error: Operation not permitted
c9d221f8
AM
1132
1133 To compile this code as a module, choose M here: the module will
1134 be called cpu-notifier-error-inject.
1135
1136 If unsure, say N.
1137
048b9c35
AM
1138config PM_NOTIFIER_ERROR_INJECT
1139 tristate "PM notifier error injection module"
1140 depends on PM && NOTIFIER_ERROR_INJECTION
1141 default m if PM_DEBUG
1142 help
1143 This option provides the ability to inject artifical errors to
1144 PM notifier chain callbacks. It is controlled through debugfs
1145 interface /sys/kernel/debug/notifier-error-inject/pm
1146
1147 If the notifier call chain should be failed with some events
1148 notified, write the error code to "actions/<notifier event>/error".
1149
1150 Example: Inject PM suspend error (-12 = -ENOMEM)
1151
1152 # cd /sys/kernel/debug/notifier-error-inject/pm/
1153 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1154 # echo mem > /sys/power/state
1155 bash: echo: write error: Cannot allocate memory
1156
1157 To compile this code as a module, choose M here: the module will
1158 be called pm-notifier-error-inject.
1159
1160 If unsure, say N.
1161
9579f5bd
AM
1162config MEMORY_NOTIFIER_ERROR_INJECT
1163 tristate "Memory hotplug notifier error injection module"
1164 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1165 help
1166 This option provides the ability to inject artifical errors to
1167 memory hotplug notifier chain callbacks. It is controlled through
1168 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
1169
1170 If the notifier call chain should be failed with some events
1171 notified, write the error code to "actions/<notifier event>/error".
1172
1173 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
1174
1175 # cd /sys/kernel/debug/notifier-error-inject/memory
1176 # echo -12 > actions/MEM_GOING_OFFLINE/error
1177 # echo offline > /sys/devices/system/memory/memoryXXX/state
1178 bash: echo: write error: Cannot allocate memory
1179
1180 To compile this code as a module, choose M here: the module will
1181 be called pSeries-reconfig-notifier-error-inject.
1182
1183 If unsure, say N.
1184
08dfb4dd
AM
1185config PSERIES_RECONFIG_NOTIFIER_ERROR_INJECT
1186 tristate "pSeries reconfig notifier error injection module"
1187 depends on PPC_PSERIES && NOTIFIER_ERROR_INJECTION
1188 help
1189 This option provides the ability to inject artifical errors to
1190 pSeries reconfig notifier chain callbacks. It is controlled
1191 through debugfs interface under
1192 /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/
1193
1194 If the notifier call chain should be failed with some events
1195 notified, write the error code to "actions/<notifier event>/error".
1196
1197 To compile this code as a module, choose M here: the module will
1198 be called memory-notifier-error-inject.
1199
1200 If unsure, say N.
1201
6ff1cb35 1202config FAULT_INJECTION
1ab8509a
AM
1203 bool "Fault-injection framework"
1204 depends on DEBUG_KERNEL
329409ae
AM
1205 help
1206 Provide fault-injection framework.
1207 For more details, see Documentation/fault-injection/.
6ff1cb35 1208
8a8b6502 1209config FAILSLAB
1ab8509a
AM
1210 bool "Fault-injection capability for kmalloc"
1211 depends on FAULT_INJECTION
773ff60e 1212 depends on SLAB || SLUB
8a8b6502 1213 help
1ab8509a 1214 Provide fault-injection capability for kmalloc.
8a8b6502 1215
933e312e
AM
1216config FAIL_PAGE_ALLOC
1217 bool "Fault-injection capabilitiy for alloc_pages()"
1ab8509a 1218 depends on FAULT_INJECTION
933e312e 1219 help
1ab8509a 1220 Provide fault-injection capability for alloc_pages().
933e312e 1221
c17bb495 1222config FAIL_MAKE_REQUEST
86327d19 1223 bool "Fault-injection capability for disk IO"
581d4e28 1224 depends on FAULT_INJECTION && BLOCK
c17bb495 1225 help
1ab8509a 1226 Provide fault-injection capability for disk IO.
c17bb495 1227
581d4e28 1228config FAIL_IO_TIMEOUT
f4d01439 1229 bool "Fault-injection capability for faking disk interrupts"
581d4e28
JA
1230 depends on FAULT_INJECTION && BLOCK
1231 help
1232 Provide fault-injection capability on end IO handling. This
1233 will make the block layer "forget" an interrupt as configured,
1234 thus exercising the error handling.
1235
1236 Only works with drivers that use the generic timeout handling,
1237 for others it wont do anything.
1238
1b676f70
PF
1239config FAIL_MMC_REQUEST
1240 bool "Fault-injection capability for MMC IO"
1241 select DEBUG_FS
1242 depends on FAULT_INJECTION && MMC
1243 help
1244 Provide fault-injection capability for MMC IO.
1245 This will make the mmc core return data errors. This is
1246 useful to test the error handling in the mmc block device
1247 and to test how the mmc host driver handles retries from
1248 the block device.
1249
6ff1cb35
AM
1250config FAULT_INJECTION_DEBUG_FS
1251 bool "Debugfs entries for fault-injection capabilities"
1ab8509a 1252 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
6ff1cb35 1253 help
1ab8509a 1254 Enable configuration of fault-injection capabilities via debugfs.
1df49008
AM
1255
1256config FAULT_INJECTION_STACKTRACE_FILTER
1257 bool "stacktrace filter for fault-injection capabilities"
1258 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
6d690dca 1259 depends on !X86_64
1df49008 1260 select STACKTRACE
89bace65 1261 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1df49008
AM
1262 help
1263 Provide stacktrace filter for fault-injection capabilities
267c4025 1264
9745512c
AV
1265config LATENCYTOP
1266 bool "Latency measuring infrastructure"
625fdcaa
RD
1267 depends on HAVE_LATENCYTOP_SUPPORT
1268 depends on DEBUG_KERNEL
1269 depends on STACKTRACE_SUPPORT
1270 depends on PROC_FS
89bace65 1271 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
9745512c
AV
1272 select KALLSYMS
1273 select KALLSYMS_ALL
1274 select STACKTRACE
1275 select SCHEDSTATS
1276 select SCHED_DEBUG
9745512c
AV
1277 help
1278 Enable this option if you want to use the LatencyTOP tool
1279 to find out which userspace is blocking on what kernel operations.
1280
6a11f75b 1281source mm/Kconfig.debug
16444a8a
ACM
1282source kernel/trace/Kconfig
1283
f212ec4b 1284config PROVIDE_OHCI1394_DMA_INIT
080de8c2 1285 bool "Remote debugging over FireWire early on boot"
f212ec4b
BK
1286 depends on PCI && X86
1287 help
1288 If you want to debug problems which hang or crash the kernel early
1289 on boot and the crashing machine has a FireWire port, you can use
1290 this feature to remotely access the memory of the crashed machine
1291 over FireWire. This employs remote DMA as part of the OHCI1394
1292 specification which is now the standard for FireWire controllers.
1293
1294 With remote DMA, you can monitor the printk buffer remotely using
1295 firescope and access all memory below 4GB using fireproxy from gdb.
1296 Even controlling a kernel debugger is possible using remote DMA.
1297
1298 Usage:
1299
1300 If ohci1394_dma=early is used as boot parameter, it will initialize
1301 all OHCI1394 controllers which are found in the PCI config space.
1302
1303 As all changes to the FireWire bus such as enabling and disabling
1304 devices cause a bus reset and thereby disable remote DMA for all
1305 devices, be sure to have the cable plugged and FireWire enabled on
1306 the debugging host before booting the debug target for debugging.
1307
1308 This code (~1k) is freed after boot. By then, the firewire stack
1309 in charge of the OHCI-1394 controllers should be used instead.
1310
1311 See Documentation/debugging-via-ohci1394.txt for more information.
9745512c 1312
080de8c2
SR
1313config FIREWIRE_OHCI_REMOTE_DMA
1314 bool "Remote debugging over FireWire with firewire-ohci"
1315 depends on FIREWIRE_OHCI
1316 help
1317 This option lets you use the FireWire bus for remote debugging
1318 with help of the firewire-ohci driver. It enables unfiltered
1319 remote DMA in firewire-ohci.
1320 See Documentation/debugging-via-ohci1394.txt for more information.
1321
1322 If unsure, say N.
1323
152de30b 1324config BUILD_DOCSRC
3794f3e8
RD
1325 bool "Build targets in Documentation/ tree"
1326 depends on HEADERS_CHECK
1327 help
1328 This option attempts to build objects from the source files in the
1329 kernel Documentation/ tree.
1330
1331 Say N if you are unsure.
1332
e9d376f0 1333config DYNAMIC_DEBUG
86151fdf 1334 bool "Enable dynamic printk() support"
346e15be
JB
1335 default n
1336 depends on PRINTK
86151fdf 1337 depends on DEBUG_FS
346e15be
JB
1338 help
1339
1340 Compiles debug level messages into the kernel, which would not
1341 otherwise be available at runtime. These messages can then be
86151fdf
JB
1342 enabled/disabled based on various levels of scope - per source file,
1343 function, module, format string, and line number. This mechanism
29e36c9f
JC
1344 implicitly compiles in all pr_debug() and dev_dbg() calls, which
1345 enlarges the kernel text size by about 2%.
1346
1347 If a source file is compiled with DEBUG flag set, any
1348 pr_debug() calls in it are enabled by default, but can be
1349 disabled at runtime as below. Note that DEBUG flag is
1350 turned on by many CONFIG_*DEBUG* options.
346e15be
JB
1351
1352 Usage:
1353
2b2f68b5 1354 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
86151fdf
JB
1355 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1356 filesystem must first be mounted before making use of this feature.
2b2f68b5 1357 We refer the control file as: <debugfs>/dynamic_debug/control. This
86151fdf
JB
1358 file contains a list of the debug statements that can be enabled. The
1359 format for each line of the file is:
346e15be 1360
86151fdf 1361 filename:lineno [module]function flags format
346e15be 1362
86151fdf
JB
1363 filename : source file of the debug statement
1364 lineno : line number of the debug statement
1365 module : module that contains the debug statement
1366 function : function that contains the debug statement
29e36c9f 1367 flags : '=p' means the line is turned 'on' for printing
86151fdf 1368 format : the format used for the debug statement
346e15be
JB
1369
1370 From a live system:
1371
2b2f68b5 1372 nullarbor:~ # cat <debugfs>/dynamic_debug/control
86151fdf 1373 # filename:lineno [module]function flags format
29e36c9f
JC
1374 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1375 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1376 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
346e15be 1377
86151fdf 1378 Example usage:
346e15be 1379
86151fdf
JB
1380 // enable the message at line 1603 of file svcsock.c
1381 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
2b2f68b5 1382 <debugfs>/dynamic_debug/control
346e15be 1383
86151fdf
JB
1384 // enable all the messages in file svcsock.c
1385 nullarbor:~ # echo -n 'file svcsock.c +p' >
2b2f68b5 1386 <debugfs>/dynamic_debug/control
346e15be 1387
86151fdf
JB
1388 // enable all the messages in the NFS server module
1389 nullarbor:~ # echo -n 'module nfsd +p' >
2b2f68b5 1390 <debugfs>/dynamic_debug/control
346e15be 1391
86151fdf
JB
1392 // enable all 12 messages in the function svc_process()
1393 nullarbor:~ # echo -n 'func svc_process +p' >
2b2f68b5 1394 <debugfs>/dynamic_debug/control
346e15be 1395
86151fdf
JB
1396 // disable all 12 messages in the function svc_process()
1397 nullarbor:~ # echo -n 'func svc_process -p' >
2b2f68b5 1398 <debugfs>/dynamic_debug/control
346e15be 1399
86151fdf 1400 See Documentation/dynamic-debug-howto.txt for additional information.
346e15be 1401
5ee00bd4
JR
1402config DMA_API_DEBUG
1403 bool "Enable debugging of DMA-API usage"
1404 depends on HAVE_DMA_API_DEBUG
1405 help
1406 Enable this option to debug the use of the DMA API by device drivers.
1407 With this option you will be able to detect common bugs in device
1408 drivers like double-freeing of DMA mappings or freeing mappings that
1409 were never allocated.
1410 This option causes a performance degredation. Use only if you want
1411 to debug device drivers. If unsure, say N.
346e15be 1412
86a89380
LB
1413config ATOMIC64_SELFTEST
1414 bool "Perform an atomic64_t self-test at boot"
1415 help
1416 Enable this option to test the atomic64_t functions at boot.
1417
1418 If unsure, say N.
1419
400fb7f6
DW
1420config ASYNC_RAID6_TEST
1421 tristate "Self test for hardware accelerated raid6 recovery"
1422 depends on ASYNC_RAID6_RECOV
1423 select ASYNC_MEMCPY
1424 ---help---
1425 This is a one-shot self test that permutes through the
1426 recovery of all the possible two disk failure scenarios for a
1427 N-disk array. Recovery is performed with the asynchronous
1428 raid6 recovery routines, and will optionally use an offload
1429 engine if one is available.
1430
1431 If unsure, say N.
1432
267c4025 1433source "samples/Kconfig"
dc7d5527
JW
1434
1435source "lib/Kconfig.kgdb"
0a4af3b0
PE
1436
1437source "lib/Kconfig.kmemcheck"
33ee3b2e
AD
1438
1439config TEST_KSTRTOX
1440 tristate "Test kstrto*() family of functions at runtime"