Bluetooth: Fix potential bad memory access with sysfs files
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / lib / Kconfig.debug
CommitLineData
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1
2config PRINTK_TIME
3 bool "Show timing information on printks"
d3b8b6e5 4 depends on PRINTK
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5 help
6 Selecting this option causes timing information to be
7 included in printk output. This allows you to measure
8 the interval between kernel operations, including bootup
9 operations. This is useful for identifying long delays
10 in kernel startup.
11
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12config ENABLE_WARN_DEPRECATED
13 bool "Enable __deprecated logic"
14 default y
15 help
16 Enable the __deprecated logic in the kernel build.
17 Disable this to suppress the "warning: 'foo' is deprecated
18 (declared at kernel/power/somefile.c:1234)" messages.
19
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20config ENABLE_MUST_CHECK
21 bool "Enable __must_check logic"
22 default y
23 help
24 Enable the __must_check logic in the kernel build. Disable this to
25 suppress the "warning: ignoring return value of 'foo', declared with
26 attribute warn_unused_result" messages.
1da177e4 27
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28config FRAME_WARN
29 int "Warn for stack frames larger than (needs gcc 4.4)"
30 range 0 8192
31 default 1024 if !64BIT
32 default 2048 if 64BIT
33 help
34 Tell gcc to warn at build time for stack frames larger than this.
35 Setting this too low will cause a lot of warnings.
36 Setting it to 0 disables the warning.
37 Requires gcc 4.4
38
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39config MAGIC_SYSRQ
40 bool "Magic SysRq key"
f346f4b3 41 depends on !UML
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42 help
43 If you say Y here, you will have some control over the system even
44 if the system crashes for example during kernel debugging (e.g., you
45 will be able to flush the buffer cache to disk, reboot the system
46 immediately or dump some status information). This is accomplished
47 by pressing various keys while holding SysRq (Alt+PrintScreen). It
48 also works on a serial console (on PC hardware at least), if you
49 send a BREAK and then within 5 seconds a command keypress. The
50 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
51 unless you really know what this hack does.
52
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53config STRIP_ASM_SYMS
54 bool "Strip assembler-generated symbols during link"
55 default n
56 help
57 Strip internal assembler-generated symbols during a link (symbols
58 that look like '.Lxxx') so they don't pollute the output of
59 get_wchan() and suchlike.
60
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61config UNUSED_SYMBOLS
62 bool "Enable unused/obsolete exported symbols"
63 default y if X86
64 help
65 Unused but exported symbols make the kernel needlessly bigger. For
66 that reason most of these unused exports will soon be removed. This
67 option is provided temporarily to provide a transition period in case
68 some external kernel module needs one of these symbols anyway. If you
69 encounter such a case in your module, consider if you are actually
70 using the right API. (rationale: since nobody in the kernel is using
71 this in a module, there is a pretty good chance it's actually the
72 wrong interface to use). If you really need the symbol, please send a
73 mail to the linux kernel mailing list mentioning the symbol and why
74 you really need it, and what the merge plan to the mainline kernel for
75 your module is.
76
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77config DEBUG_FS
78 bool "Debug Filesystem"
79 depends on SYSFS
80 help
81 debugfs is a virtual file system that kernel developers use to put
82 debugging files into. Enable this option to be able to read and
83 write to these files.
84
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85 For detailed documentation on the debugfs API, see
86 Documentation/DocBook/filesystems.
87
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88 If unsure, say N.
89
90config HEADERS_CHECK
91 bool "Run 'make headers_check' when building vmlinux"
92 depends on !UML
93 help
94 This option will extract the user-visible kernel headers whenever
95 building the kernel, and will run basic sanity checks on them to
96 ensure that exported files do not attempt to include files which
97 were not exported, etc.
98
99 If you're making modifications to header files which are
100 relevant for userspace, say 'Y', and check the headers
101 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
102 your build tree), to make sure they're suitable.
103
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104config DEBUG_SECTION_MISMATCH
105 bool "Enable full Section mismatch analysis"
e5f95c8b 106 depends on UNDEFINED
fa2144ba 107 # This option is on purpose disabled for now.
af901ca1 108 # It will be enabled when we are down to a reasonable number
fa2144ba 109 # of section mismatch warnings (< 10 for an allyesconfig build)
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110 help
111 The section mismatch analysis checks if there are illegal
112 references from one section to another section.
113 Linux will during link or during runtime drop some sections
114 and any use of code/data previously in these sections will
115 most likely result in an oops.
116 In the code functions and variables are annotated with
117 __init, __devinit etc. (see full list in include/linux/init.h)
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118 which results in the code/data being placed in specific sections.
119 The section mismatch analysis is always done after a full
120 kernel build but enabling this option will in addition
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121 do the following:
122 - Add the option -fno-inline-functions-called-once to gcc
123 When inlining a function annotated __init in a non-init
d6fbfa4f 124 function we would lose the section information and thus
91341d4b 125 the analysis would not catch the illegal reference.
d6fbfa4f 126 This option tells gcc to inline less but will also
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127 result in a larger kernel.
128 - Run the section mismatch analysis for each module/built-in.o
129 When we run the section mismatch analysis on vmlinux.o we
d6fbfa4f 130 lose valueble information about where the mismatch was
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131 introduced.
132 Running the analysis for each module/built-in.o file
133 will tell where the mismatch happens much closer to the
134 source. The drawback is that we will report the same
135 mismatch at least twice.
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136 - Enable verbose reporting from modpost to help solving
137 the section mismatches reported.
91341d4b 138
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139config DEBUG_KERNEL
140 bool "Kernel debugging"
141 help
142 Say Y here if you are developing drivers or trying to debug and
143 identify kernel problems.
144
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145config DEBUG_SHIRQ
146 bool "Debug shared IRQ handlers"
147 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
148 help
149 Enable this to generate a spurious interrupt as soon as a shared
150 interrupt handler is registered, and just before one is deregistered.
151 Drivers ought to be able to handle interrupts coming in at those
152 points; some don't and need to be caught.
153
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154config DETECT_SOFTLOCKUP
155 bool "Detect Soft Lockups"
dea20a3f 156 depends on DEBUG_KERNEL && !S390
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157 default y
158 help
159 Say Y here to enable the kernel to detect "soft lockups",
160 which are bugs that cause the kernel to loop in kernel
9c44bc03 161 mode for more than 60 seconds, without giving other tasks a
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162 chance to run.
163
164 When a soft-lockup is detected, the kernel will print the
165 current stack trace (which you should report), but the
166 system will stay locked up. This feature has negligible
167 overhead.
168
169 (Note that "hard lockups" are separate type of bugs that
170 can be detected via the NMI-watchdog, on platforms that
171 support it.)
172
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173config BOOTPARAM_SOFTLOCKUP_PANIC
174 bool "Panic (Reboot) On Soft Lockups"
175 depends on DETECT_SOFTLOCKUP
176 help
177 Say Y here to enable the kernel to panic on "soft lockups",
178 which are bugs that cause the kernel to loop in kernel
179 mode for more than 60 seconds, without giving other tasks a
180 chance to run.
181
182 The panic can be used in combination with panic_timeout,
183 to cause the system to reboot automatically after a
184 lockup has been detected. This feature is useful for
185 high-availability systems that have uptime guarantees and
186 where a lockup must be resolved ASAP.
187
188 Say N if unsure.
189
190config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
191 int
192 depends on DETECT_SOFTLOCKUP
193 range 0 1
194 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
195 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
196
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197config DETECT_HUNG_TASK
198 bool "Detect Hung Tasks"
199 depends on DEBUG_KERNEL
77d05632 200 default DETECT_SOFTLOCKUP
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201 help
202 Say Y here to enable the kernel to detect "hung tasks",
203 which are bugs that cause the task to be stuck in
204 uninterruptible "D" state indefinitiley.
205
206 When a hung task is detected, the kernel will print the
207 current stack trace (which you should report), but the
208 task will stay in uninterruptible state. If lockdep is
209 enabled then all held locks will also be reported. This
210 feature has negligible overhead.
211
212config BOOTPARAM_HUNG_TASK_PANIC
213 bool "Panic (Reboot) On Hung Tasks"
214 depends on DETECT_HUNG_TASK
215 help
216 Say Y here to enable the kernel to panic on "hung tasks",
217 which are bugs that cause the kernel to leave a task stuck
218 in uninterruptible "D" state.
219
220 The panic can be used in combination with panic_timeout,
221 to cause the system to reboot automatically after a
222 hung task has been detected. This feature is useful for
223 high-availability systems that have uptime guarantees and
224 where a hung tasks must be resolved ASAP.
225
226 Say N if unsure.
227
228config BOOTPARAM_HUNG_TASK_PANIC_VALUE
229 int
230 depends on DETECT_HUNG_TASK
231 range 0 1
232 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
233 default 1 if BOOTPARAM_HUNG_TASK_PANIC
234
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235config SCHED_DEBUG
236 bool "Collect scheduler debugging info"
237 depends on DEBUG_KERNEL && PROC_FS
238 default y
239 help
240 If you say Y here, the /proc/sched_debug file will be provided
241 that can help debug the scheduler. The runtime overhead of this
242 option is minimal.
243
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244config SCHEDSTATS
245 bool "Collect scheduler statistics"
246 depends on DEBUG_KERNEL && PROC_FS
247 help
248 If you say Y here, additional code will be inserted into the
249 scheduler and related routines to collect statistics about
250 scheduler behavior and provide them in /proc/schedstat. These
251 stats may be useful for both tuning and debugging the scheduler
252 If you aren't debugging the scheduler or trying to tune a specific
253 application, you can say N to avoid the very slight overhead
254 this adds.
255
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256config TIMER_STATS
257 bool "Collect kernel timers statistics"
258 depends on DEBUG_KERNEL && PROC_FS
259 help
260 If you say Y here, additional code will be inserted into the
261 timer routines to collect statistics about kernel timers being
262 reprogrammed. The statistics can be read from /proc/timer_stats.
263 The statistics collection is started by writing 1 to /proc/timer_stats,
264 writing 0 stops it. This feature is useful to collect information
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265 about timer usage patterns in kernel and userspace. This feature
266 is lightweight if enabled in the kernel config but not activated
267 (it defaults to deactivated on bootup and will only be activated
268 if some application like powertop activates it explicitly).
82f67cd9 269
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270config DEBUG_OBJECTS
271 bool "Debug object operations"
272 depends on DEBUG_KERNEL
273 help
274 If you say Y here, additional code will be inserted into the
275 kernel to track the life time of various objects and validate
276 the operations on those objects.
277
278config DEBUG_OBJECTS_SELFTEST
279 bool "Debug objects selftest"
280 depends on DEBUG_OBJECTS
281 help
282 This enables the selftest of the object debug code.
283
284config DEBUG_OBJECTS_FREE
285 bool "Debug objects in freed memory"
286 depends on DEBUG_OBJECTS
287 help
288 This enables checks whether a k/v free operation frees an area
289 which contains an object which has not been deactivated
290 properly. This can make kmalloc/kfree-intensive workloads
291 much slower.
292
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293config DEBUG_OBJECTS_TIMERS
294 bool "Debug timer objects"
295 depends on DEBUG_OBJECTS
296 help
297 If you say Y here, additional code will be inserted into the
298 timer routines to track the life time of timer objects and
299 validate the timer operations.
300
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301config DEBUG_OBJECTS_WORK
302 bool "Debug work objects"
303 depends on DEBUG_OBJECTS
304 help
305 If you say Y here, additional code will be inserted into the
306 work queue routines to track the life time of work objects and
307 validate the work operations.
308
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309config DEBUG_OBJECTS_ENABLE_DEFAULT
310 int "debug_objects bootup default value (0-1)"
311 range 0 1
312 default "1"
313 depends on DEBUG_OBJECTS
314 help
315 Debug objects boot parameter default value
316
1da177e4 317config DEBUG_SLAB
4a2f0acf 318 bool "Debug slab memory allocations"
7d46d9e6 319 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
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320 help
321 Say Y here to have the kernel do limited verification on memory
322 allocation as well as poisoning memory on free to catch use of freed
323 memory. This can make kmalloc/kfree-intensive workloads much slower.
324
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325config DEBUG_SLAB_LEAK
326 bool "Memory leak debugging"
327 depends on DEBUG_SLAB
328
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329config SLUB_DEBUG_ON
330 bool "SLUB debugging on by default"
7d46d9e6 331 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
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332 default n
333 help
334 Boot with debugging on by default. SLUB boots by default with
335 the runtime debug capabilities switched off. Enabling this is
336 equivalent to specifying the "slub_debug" parameter on boot.
337 There is no support for more fine grained debug control like
338 possible with slub_debug=xxx. SLUB debugging may be switched
339 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
340 "slub_debug=-".
341
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342config SLUB_STATS
343 default n
344 bool "Enable SLUB performance statistics"
5b06c853 345 depends on SLUB && SLUB_DEBUG && SYSFS
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346 help
347 SLUB statistics are useful to debug SLUBs allocation behavior in
348 order find ways to optimize the allocator. This should never be
349 enabled for production use since keeping statistics slows down
350 the allocator by a few percentage points. The slabinfo command
351 supports the determination of the most active slabs to figure
352 out which slabs are relevant to a particular load.
353 Try running: slabinfo -DA
354
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355config DEBUG_KMEMLEAK
356 bool "Kernel memory leak detector"
dfcc3e6a 357 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
660e2aca 358 (X86 || ARM || PPC || S390 || SUPERH)
dfcc3e6a 359
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360 select DEBUG_FS if SYSFS
361 select STACKTRACE if STACKTRACE_SUPPORT
362 select KALLSYMS
b60e26a2 363 select CRC32
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364 help
365 Say Y here if you want to enable the memory leak
366 detector. The memory allocation/freeing is traced in a way
367 similar to the Boehm's conservative garbage collector, the
368 difference being that the orphan objects are not freed but
369 only shown in /sys/kernel/debug/kmemleak. Enabling this
370 feature will introduce an overhead to memory
371 allocations. See Documentation/kmemleak.txt for more
372 details.
373
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374 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
375 of finding leaks due to the slab objects poisoning.
376
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377 In order to access the kmemleak file, debugfs needs to be
378 mounted (usually at /sys/kernel/debug).
379
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380config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
381 int "Maximum kmemleak early log entries"
382 depends on DEBUG_KMEMLEAK
dfcc3e6a 383 range 200 40000
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384 default 400
385 help
386 Kmemleak must track all the memory allocations to avoid
387 reporting false positives. Since memory may be allocated or
388 freed before kmemleak is initialised, an early log buffer is
389 used to store these actions. If kmemleak reports "early log
390 buffer exceeded", please increase this value.
391
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392config DEBUG_KMEMLEAK_TEST
393 tristate "Simple test for the kernel memory leak detector"
394 depends on DEBUG_KMEMLEAK
395 help
396 Say Y or M here to build a test for the kernel memory leak
397 detector. This option enables a module that explicitly leaks
398 memory.
399
400 If unsure, say N.
401
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402config DEBUG_PREEMPT
403 bool "Debug preemptible kernel"
01deab98 404 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
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405 default y
406 help
407 If you say Y here then the kernel will use a debug variant of the
408 commonly used smp_processor_id() function and will print warnings
409 if kernel code uses it in a preemption-unsafe way. Also, the kernel
410 will detect preemption count underflows.
411
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412config DEBUG_RT_MUTEXES
413 bool "RT Mutex debugging, deadlock detection"
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414 depends on DEBUG_KERNEL && RT_MUTEXES
415 help
416 This allows rt mutex semantics violations and rt mutex related
417 deadlocks (lockups) to be detected and reported automatically.
418
419config DEBUG_PI_LIST
420 bool
421 default y
422 depends on DEBUG_RT_MUTEXES
423
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424config RT_MUTEX_TESTER
425 bool "Built-in scriptable tester for rt-mutexes"
a1583d3e 426 depends on DEBUG_KERNEL && RT_MUTEXES
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427 help
428 This option enables a rt-mutex tester.
429
1da177e4 430config DEBUG_SPINLOCK
4d9f34ad 431 bool "Spinlock and rw-lock debugging: basic checks"
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432 depends on DEBUG_KERNEL
433 help
434 Say Y here and build SMP to catch missing spinlock initialization
435 and certain other kinds of spinlock errors commonly made. This is
436 best used in conjunction with the NMI watchdog so that spinlock
437 deadlocks are also debuggable.
438
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439config DEBUG_MUTEXES
440 bool "Mutex debugging: basic checks"
441 depends on DEBUG_KERNEL
442 help
443 This feature allows mutex semantics violations to be detected and
444 reported.
445
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446config DEBUG_LOCK_ALLOC
447 bool "Lock debugging: detect incorrect freeing of live locks"
517e7aa5 448 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
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449 select DEBUG_SPINLOCK
450 select DEBUG_MUTEXES
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451 select LOCKDEP
452 help
453 This feature will check whether any held lock (spinlock, rwlock,
454 mutex or rwsem) is incorrectly freed by the kernel, via any of the
455 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
456 vfree(), etc.), whether a live lock is incorrectly reinitialized via
457 spin_lock_init()/mutex_init()/etc., or whether there is any lock
458 held during task exit.
459
460config PROVE_LOCKING
461 bool "Lock debugging: prove locking correctness"
517e7aa5 462 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
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463 select LOCKDEP
464 select DEBUG_SPINLOCK
465 select DEBUG_MUTEXES
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466 select DEBUG_LOCK_ALLOC
467 default n
468 help
469 This feature enables the kernel to prove that all locking
470 that occurs in the kernel runtime is mathematically
471 correct: that under no circumstance could an arbitrary (and
472 not yet triggered) combination of observed locking
473 sequences (on an arbitrary number of CPUs, running an
474 arbitrary number of tasks and interrupt contexts) cause a
475 deadlock.
476
477 In short, this feature enables the kernel to report locking
478 related deadlocks before they actually occur.
479
480 The proof does not depend on how hard and complex a
481 deadlock scenario would be to trigger: how many
482 participant CPUs, tasks and irq-contexts would be needed
483 for it to trigger. The proof also does not depend on
484 timing: if a race and a resulting deadlock is possible
485 theoretically (no matter how unlikely the race scenario
486 is), it will be proven so and will immediately be
487 reported by the kernel (once the event is observed that
488 makes the deadlock theoretically possible).
489
490 If a deadlock is impossible (i.e. the locking rules, as
491 observed by the kernel, are mathematically correct), the
492 kernel reports nothing.
493
494 NOTE: this feature can also be enabled for rwlocks, mutexes
495 and rwsems - in which case all dependencies between these
496 different locking variants are observed and mapped too, and
497 the proof of observed correctness is also maintained for an
498 arbitrary combination of these separate locking variants.
499
500 For more details, see Documentation/lockdep-design.txt.
501
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502config PROVE_RCU
503 bool "RCU debugging: prove RCU correctness"
504 depends on PROVE_LOCKING
505 default n
506 help
507 This feature enables lockdep extensions that check for correct
508 use of RCU APIs. This is currently under development. Say Y
509 if you want to debug RCU usage or help work on the PROVE_RCU
510 feature.
511
512 Say N if you are unsure.
513
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514config LOCKDEP
515 bool
517e7aa5 516 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
4d9f34ad 517 select STACKTRACE
00540e5d 518 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
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519 select KALLSYMS
520 select KALLSYMS_ALL
521
f20786ff 522config LOCK_STAT
fdfb870f 523 bool "Lock usage statistics"
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524 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
525 select LOCKDEP
526 select DEBUG_SPINLOCK
527 select DEBUG_MUTEXES
528 select DEBUG_LOCK_ALLOC
529 default n
530 help
531 This feature enables tracking lock contention points
532
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533 For more details, see Documentation/lockstat.txt
534
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535 This also enables lock events required by "perf lock",
536 subcommand of perf.
537 If you want to use "perf lock", you also need to turn on
538 CONFIG_EVENT_TRACING.
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539
540 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
dd8b1cf6 541 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
84c6f88f 542
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543config DEBUG_LOCKDEP
544 bool "Lock dependency engine debugging"
517e7aa5 545 depends on DEBUG_KERNEL && LOCKDEP
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546 help
547 If you say Y here, the lock dependency engine will do
548 additional runtime checks to debug itself, at the price
549 of more runtime overhead.
550
551config TRACE_IRQFLAGS
517e7aa5 552 depends on DEBUG_KERNEL
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553 bool
554 default y
555 depends on TRACE_IRQFLAGS_SUPPORT
556 depends on PROVE_LOCKING
557
1da177e4 558config DEBUG_SPINLOCK_SLEEP
4d9f34ad 559 bool "Spinlock debugging: sleep-inside-spinlock checking"
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560 depends on DEBUG_KERNEL
561 help
562 If you say Y here, various routines which may sleep will become very
563 noisy if they are called with a spinlock held.
564
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565config DEBUG_LOCKING_API_SELFTESTS
566 bool "Locking API boot-time self-tests"
567 depends on DEBUG_KERNEL
568 help
569 Say Y here if you want the kernel to run a short self-test during
570 bootup. The self-test checks whether common types of locking bugs
571 are detected by debugging mechanisms or not. (if you disable
572 lock debugging then those bugs wont be detected of course.)
573 The following locking APIs are covered: spinlocks, rwlocks,
574 mutexes and rwsems.
575
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576config STACKTRACE
577 bool
578 depends on STACKTRACE_SUPPORT
579
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580config DEBUG_KOBJECT
581 bool "kobject debugging"
582 depends on DEBUG_KERNEL
583 help
584 If you say Y here, some extra kobject debugging messages will be sent
585 to the syslog.
586
587config DEBUG_HIGHMEM
588 bool "Highmem debugging"
589 depends on DEBUG_KERNEL && HIGHMEM
590 help
591 This options enables addition error checking for high memory systems.
592 Disable for production systems.
593
594config DEBUG_BUGVERBOSE
595 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
c8538a7a 596 depends on BUG
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597 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
598 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
8420e7ef 599 default y
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600 help
601 Say Y here to make BUG() panics output the file name and line number
602 of the BUG call as well as the EIP and oops trace. This aids
603 debugging but costs about 70-100K of memory.
604
605config DEBUG_INFO
606 bool "Compile the kernel with debug info"
607 depends on DEBUG_KERNEL
608 help
609 If you say Y here the resulting kernel image will include
610 debugging info resulting in a larger kernel image.
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611 This adds debug symbols to the kernel and modules (gcc -g), and
612 is needed if you intend to use kernel crashdump or binary object
613 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
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614 Say Y here only if you plan to debug the kernel.
615
616 If unsure, say N.
617
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618config DEBUG_VM
619 bool "Debug VM"
620 depends on DEBUG_KERNEL
621 help
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622 Enable this to turn on extended checks in the virtual-memory system
623 that may impact performance.
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624
625 If unsure, say N.
626
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627config DEBUG_VIRTUAL
628 bool "Debug VM translations"
629 depends on DEBUG_KERNEL && X86
630 help
631 Enable some costly sanity checks in virtual to page code. This can
632 catch mistakes with virt_to_page() and friends.
633
634 If unsure, say N.
635
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636config DEBUG_NOMMU_REGIONS
637 bool "Debug the global anon/private NOMMU mapping region tree"
638 depends on DEBUG_KERNEL && !MMU
639 help
640 This option causes the global tree of anonymous and private mapping
641 regions to be regularly checked for invalid topology.
642
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643config DEBUG_WRITECOUNT
644 bool "Debug filesystem writers count"
645 depends on DEBUG_KERNEL
646 help
647 Enable this to catch wrong use of the writers count in struct
648 vfsmount. This will increase the size of each file struct by
649 32 bits.
650
651 If unsure, say N.
652
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653config DEBUG_MEMORY_INIT
654 bool "Debug memory initialisation" if EMBEDDED
655 default !EMBEDDED
656 help
657 Enable this for additional checks during memory initialisation.
658 The sanity checks verify aspects of the VM such as the memory model
659 and other information provided by the architecture. Verbose
660 information will be printed at KERN_DEBUG loglevel depending
661 on the mminit_loglevel= command-line option.
662
663 If unsure, say Y
664
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665config DEBUG_LIST
666 bool "Debug linked list manipulation"
667 depends on DEBUG_KERNEL
668 help
669 Enable this to turn on extended checks in the linked-list
670 walking routines.
671
672 If unsure, say N.
673
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674config DEBUG_SG
675 bool "Debug SG table operations"
676 depends on DEBUG_KERNEL
677 help
678 Enable this to turn on checks on scatter-gather tables. This can
679 help find problems with drivers that do not properly initialize
680 their sg tables.
681
682 If unsure, say N.
683
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684config DEBUG_NOTIFIERS
685 bool "Debug notifier call chains"
686 depends on DEBUG_KERNEL
687 help
688 Enable this to turn on sanity checking for notifier call chains.
689 This is most useful for kernel developers to make sure that
690 modules properly unregister themselves from notifier chains.
691 This is a relatively cheap check but if you care about maximum
692 performance, say N.
693
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694config DEBUG_CREDENTIALS
695 bool "Debug credential management"
696 depends on DEBUG_KERNEL
697 help
698 Enable this to turn on some debug checking for credential
699 management. The additional code keeps track of the number of
700 pointers from task_structs to any given cred struct, and checks to
701 see that this number never exceeds the usage count of the cred
702 struct.
703
704 Furthermore, if SELinux is enabled, this also checks that the
705 security pointer in the cred struct is never seen to be invalid.
706
707 If unsure, say N.
708
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709#
710# Select this config option from the architecture Kconfig, if it
711# it is preferred to always offer frame pointers as a config
712# option on the architecture (regardless of KERNEL_DEBUG):
713#
714config ARCH_WANT_FRAME_POINTERS
715 bool
716 help
717
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718config FRAME_POINTER
719 bool "Compile the kernel with frame pointers"
b920de1b 720 depends on DEBUG_KERNEL && \
75ee034a 721 (CRIS || M68K || M68KNOMMU || FRV || UML || \
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722 AVR32 || SUPERH || BLACKFIN || MN10300) || \
723 ARCH_WANT_FRAME_POINTERS
724 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
725 help
726 If you say Y here the resulting kernel image will be slightly
727 larger and slower, but it gives very useful debugging information
728 in case of kernel bugs. (precise oopses/stacktraces/warnings)
1da177e4 729
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730config BOOT_PRINTK_DELAY
731 bool "Delay each boot printk message by N milliseconds"
732 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
733 help
734 This build option allows you to read kernel boot messages
735 by inserting a short delay after each one. The delay is
736 specified in milliseconds on the kernel command line,
737 using "boot_delay=N".
738
739 It is likely that you would also need to use "lpj=M" to preset
740 the "loops per jiffie" value.
741 See a previous boot log for the "lpj" value to use for your
742 system, and then set "lpj=M" before setting "boot_delay=N".
743 NOTE: Using this option may adversely affect SMP systems.
744 I.e., processors other than the first one may not boot up.
745 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
746 what it believes to be lockup conditions.
747
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748config RCU_TORTURE_TEST
749 tristate "torture tests for RCU"
750 depends on DEBUG_KERNEL
751 default n
752 help
753 This option provides a kernel module that runs torture tests
754 on the RCU infrastructure. The kernel module may be built
755 after the fact on the running kernel to be tested, if desired.
756
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757 Say Y here if you want RCU torture tests to be built into
758 the kernel.
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759 Say M if you want the RCU torture tests to build as a module.
760 Say N if you are unsure.
8bb31b9d 761
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762config RCU_TORTURE_TEST_RUNNABLE
763 bool "torture tests for RCU runnable by default"
764 depends on RCU_TORTURE_TEST = y
765 default n
766 help
767 This option provides a way to build the RCU torture tests
768 directly into the kernel without them starting up at boot
769 time. You can use /proc/sys/kernel/rcutorture_runnable
770 to manually override this setting. This /proc file is
771 available only when the RCU torture tests have been built
772 into the kernel.
773
774 Say Y here if you want the RCU torture tests to start during
775 boot (you probably don't).
776 Say N here if you want the RCU torture tests to start only
777 after being manually enabled via /proc.
778
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779config RCU_CPU_STALL_DETECTOR
780 bool "Check for stalled CPUs delaying RCU grace periods"
6b3ef48a 781 depends on TREE_RCU || TREE_PREEMPT_RCU
8bfb2f8e 782 default y
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783 help
784 This option causes RCU to printk information on which
785 CPUs are delaying the current grace period, but only when
786 the grace period extends for excessive time periods.
67182ae1 787
4c54005c 788 Say N if you want to disable such checks.
67182ae1 789
4c54005c 790 Say Y if you are unsure.
67182ae1 791
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792config RCU_CPU_STALL_VERBOSE
793 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
794 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
795 default n
796 help
797 This option causes RCU to printk detailed per-task information
798 for any tasks that are stalling the current RCU grace period.
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799
800 Say N if you are unsure.
801
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802 Say Y if you want to enable such checks.
803
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804config KPROBES_SANITY_TEST
805 bool "Kprobes sanity tests"
806 depends on DEBUG_KERNEL
807 depends on KPROBES
808 default n
809 help
810 This option provides for testing basic kprobes functionality on
811 boot. A sample kprobe, jprobe and kretprobe are inserted and
812 verified for functionality.
813
814 Say N if you are unsure.
815
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816config BACKTRACE_SELF_TEST
817 tristate "Self test for the backtrace code"
818 depends on DEBUG_KERNEL
819 default n
820 help
821 This option provides a kernel module that can be used to test
822 the kernel stack backtrace code. This option is not useful
823 for distributions or general kernels, but only for kernel
824 developers working on architecture code.
825
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826 Note that if you want to also test saved backtraces, you will
827 have to enable STACKTRACE as well.
828
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829 Say N if you are unsure.
830
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831config DEBUG_BLOCK_EXT_DEVT
832 bool "Force extended block device numbers and spread them"
833 depends on DEBUG_KERNEL
834 depends on BLOCK
759f8ca3 835 default n
870d6656 836 help
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837 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
838 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
839 YOU ARE DOING. Distros, please enable this and fix whatever
840 is broken.
841
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842 Conventionally, block device numbers are allocated from
843 predetermined contiguous area. However, extended block area
844 may introduce non-contiguous block device numbers. This
845 option forces most block device numbers to be allocated from
846 the extended space and spreads them to discover kernel or
847 userland code paths which assume predetermined contiguous
848 device number allocation.
849
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850 Note that turning on this debug option shuffles all the
851 device numbers for all IDE and SCSI devices including libata
852 ones, so root partition specified using device number
853 directly (via rdev or root=MAJ:MIN) won't work anymore.
854 Textual device names (root=/dev/sdXn) will continue to work.
855
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856 Say N if you are unsure.
857
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858config DEBUG_FORCE_WEAK_PER_CPU
859 bool "Force weak per-cpu definitions"
860 depends on DEBUG_KERNEL
861 help
862 s390 and alpha require percpu variables in modules to be
863 defined weak to work around addressing range issue which
864 puts the following two restrictions on percpu variable
865 definitions.
866
867 1. percpu symbols must be unique whether static or not
868 2. percpu variables can't be defined inside a function
869
870 To ensure that generic code follows the above rules, this
871 option forces all percpu variables to be defined as weak.
872
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873config LKDTM
874 tristate "Linux Kernel Dump Test Tool Module"
0347af4e 875 depends on DEBUG_FS
fddd9cf8 876 depends on BLOCK
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877 default n
878 help
879 This module enables testing of the different dumping mechanisms by
880 inducing system failures at predefined crash points.
881 If you don't need it: say N
882 Choose M here to compile this code as a module. The module will be
883 called lkdtm.
884
885 Documentation on how to use the module can be found in
0347af4e 886 Documentation/fault-injection/provoke-crashes.txt
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887
888config FAULT_INJECTION
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889 bool "Fault-injection framework"
890 depends on DEBUG_KERNEL
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891 help
892 Provide fault-injection framework.
893 For more details, see Documentation/fault-injection/.
6ff1cb35 894
8a8b6502 895config FAILSLAB
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896 bool "Fault-injection capability for kmalloc"
897 depends on FAULT_INJECTION
773ff60e 898 depends on SLAB || SLUB
8a8b6502 899 help
1ab8509a 900 Provide fault-injection capability for kmalloc.
8a8b6502 901
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902config FAIL_PAGE_ALLOC
903 bool "Fault-injection capabilitiy for alloc_pages()"
1ab8509a 904 depends on FAULT_INJECTION
933e312e 905 help
1ab8509a 906 Provide fault-injection capability for alloc_pages().
933e312e 907
c17bb495 908config FAIL_MAKE_REQUEST
86327d19 909 bool "Fault-injection capability for disk IO"
581d4e28 910 depends on FAULT_INJECTION && BLOCK
c17bb495 911 help
1ab8509a 912 Provide fault-injection capability for disk IO.
c17bb495 913
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JA
914config FAIL_IO_TIMEOUT
915 bool "Faul-injection capability for faking disk interrupts"
916 depends on FAULT_INJECTION && BLOCK
917 help
918 Provide fault-injection capability on end IO handling. This
919 will make the block layer "forget" an interrupt as configured,
920 thus exercising the error handling.
921
922 Only works with drivers that use the generic timeout handling,
923 for others it wont do anything.
924
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925config FAULT_INJECTION_DEBUG_FS
926 bool "Debugfs entries for fault-injection capabilities"
1ab8509a 927 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
6ff1cb35 928 help
1ab8509a 929 Enable configuration of fault-injection capabilities via debugfs.
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930
931config FAULT_INJECTION_STACKTRACE_FILTER
932 bool "stacktrace filter for fault-injection capabilities"
933 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
6d690dca 934 depends on !X86_64
1df49008 935 select STACKTRACE
75ee034a 936 select FRAME_POINTER if !PPC && !S390
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937 help
938 Provide stacktrace filter for fault-injection capabilities
267c4025 939
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AV
940config LATENCYTOP
941 bool "Latency measuring infrastructure"
75ee034a 942 select FRAME_POINTER if !MIPS && !PPC && !S390
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AV
943 select KALLSYMS
944 select KALLSYMS_ALL
945 select STACKTRACE
946 select SCHEDSTATS
947 select SCHED_DEBUG
aa7d9350 948 depends on HAVE_LATENCYTOP_SUPPORT
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AV
949 help
950 Enable this option if you want to use the LatencyTOP tool
951 to find out which userspace is blocking on what kernel operations.
952
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953config SYSCTL_SYSCALL_CHECK
954 bool "Sysctl checks"
83ac201b 955 depends on SYSCTL
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956 ---help---
957 sys_sysctl uses binary paths that have been found challenging
958 to properly maintain and use. This enables checks that help
959 you to keep things correct.
960
6a11f75b 961source mm/Kconfig.debug
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ACM
962source kernel/trace/Kconfig
963
f212ec4b 964config PROVIDE_OHCI1394_DMA_INIT
080de8c2 965 bool "Remote debugging over FireWire early on boot"
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BK
966 depends on PCI && X86
967 help
968 If you want to debug problems which hang or crash the kernel early
969 on boot and the crashing machine has a FireWire port, you can use
970 this feature to remotely access the memory of the crashed machine
971 over FireWire. This employs remote DMA as part of the OHCI1394
972 specification which is now the standard for FireWire controllers.
973
974 With remote DMA, you can monitor the printk buffer remotely using
975 firescope and access all memory below 4GB using fireproxy from gdb.
976 Even controlling a kernel debugger is possible using remote DMA.
977
978 Usage:
979
980 If ohci1394_dma=early is used as boot parameter, it will initialize
981 all OHCI1394 controllers which are found in the PCI config space.
982
983 As all changes to the FireWire bus such as enabling and disabling
984 devices cause a bus reset and thereby disable remote DMA for all
985 devices, be sure to have the cable plugged and FireWire enabled on
986 the debugging host before booting the debug target for debugging.
987
988 This code (~1k) is freed after boot. By then, the firewire stack
989 in charge of the OHCI-1394 controllers should be used instead.
990
991 See Documentation/debugging-via-ohci1394.txt for more information.
9745512c 992
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993config FIREWIRE_OHCI_REMOTE_DMA
994 bool "Remote debugging over FireWire with firewire-ohci"
995 depends on FIREWIRE_OHCI
996 help
997 This option lets you use the FireWire bus for remote debugging
998 with help of the firewire-ohci driver. It enables unfiltered
999 remote DMA in firewire-ohci.
1000 See Documentation/debugging-via-ohci1394.txt for more information.
1001
1002 If unsure, say N.
1003
152de30b 1004config BUILD_DOCSRC
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1005 bool "Build targets in Documentation/ tree"
1006 depends on HEADERS_CHECK
1007 help
1008 This option attempts to build objects from the source files in the
1009 kernel Documentation/ tree.
1010
1011 Say N if you are unsure.
1012
e9d376f0 1013config DYNAMIC_DEBUG
86151fdf 1014 bool "Enable dynamic printk() support"
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1015 default n
1016 depends on PRINTK
86151fdf 1017 depends on DEBUG_FS
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1018 help
1019
1020 Compiles debug level messages into the kernel, which would not
1021 otherwise be available at runtime. These messages can then be
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JB
1022 enabled/disabled based on various levels of scope - per source file,
1023 function, module, format string, and line number. This mechanism
1024 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1025 this compile option is a larger kernel text size of about 2%.
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JB
1026
1027 Usage:
1028
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JB
1029 Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
1030 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1031 filesystem must first be mounted before making use of this feature.
1032 We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
1033 file contains a list of the debug statements that can be enabled. The
1034 format for each line of the file is:
346e15be 1035
86151fdf 1036 filename:lineno [module]function flags format
346e15be 1037
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JB
1038 filename : source file of the debug statement
1039 lineno : line number of the debug statement
1040 module : module that contains the debug statement
1041 function : function that contains the debug statement
1042 flags : 'p' means the line is turned 'on' for printing
1043 format : the format used for the debug statement
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JB
1044
1045 From a live system:
1046
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JB
1047 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
1048 # filename:lineno [module]function flags format
1049 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1050 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1051 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
346e15be 1052
86151fdf 1053 Example usage:
346e15be 1054
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JB
1055 // enable the message at line 1603 of file svcsock.c
1056 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1057 <debugfs>/dynamic_debug/ddebug
346e15be 1058
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JB
1059 // enable all the messages in file svcsock.c
1060 nullarbor:~ # echo -n 'file svcsock.c +p' >
1061 <debugfs>/dynamic_debug/ddebug
346e15be 1062
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JB
1063 // enable all the messages in the NFS server module
1064 nullarbor:~ # echo -n 'module nfsd +p' >
1065 <debugfs>/dynamic_debug/ddebug
346e15be 1066
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1067 // enable all 12 messages in the function svc_process()
1068 nullarbor:~ # echo -n 'func svc_process +p' >
1069 <debugfs>/dynamic_debug/ddebug
346e15be 1070
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1071 // disable all 12 messages in the function svc_process()
1072 nullarbor:~ # echo -n 'func svc_process -p' >
1073 <debugfs>/dynamic_debug/ddebug
346e15be 1074
86151fdf 1075 See Documentation/dynamic-debug-howto.txt for additional information.
346e15be 1076
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1077config DMA_API_DEBUG
1078 bool "Enable debugging of DMA-API usage"
1079 depends on HAVE_DMA_API_DEBUG
1080 help
1081 Enable this option to debug the use of the DMA API by device drivers.
1082 With this option you will be able to detect common bugs in device
1083 drivers like double-freeing of DMA mappings or freeing mappings that
1084 were never allocated.
1085 This option causes a performance degredation. Use only if you want
1086 to debug device drivers. If unsure, say N.
346e15be 1087
267c4025 1088source "samples/Kconfig"
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1089
1090source "lib/Kconfig.kgdb"
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1091
1092source "lib/Kconfig.kmemcheck"