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