Root/lib/Kconfig.debug

Source at commit b386be689295730688885552666ea40b2e639b14 created 8 years 11 months ago.
By Maarten ter Huurne, Revert "MIPS: JZ4740: reset: Initialize hibernate wakeup counters."
1
2config PRINTK_TIME
3    bool "Show timing information on printks"
4    depends on PRINTK
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. Or add printk.time=1 at boot-time.
11      See Documentation/kernel-parameters.txt
12
13config DEFAULT_MESSAGE_LOGLEVEL
14    int "Default message log level (1-7)"
15    range 1 7
16    default "4"
17    help
18      Default log level for printk statements with no specified priority.
19
20      This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
21      that are auditing their logs closely may want to set it to a lower
22      priority.
23
24config ENABLE_WARN_DEPRECATED
25    bool "Enable __deprecated logic"
26    default y
27    help
28      Enable the __deprecated logic in the kernel build.
29      Disable this to suppress the "warning: 'foo' is deprecated
30      (declared at kernel/power/somefile.c:1234)" messages.
31
32config ENABLE_MUST_CHECK
33    bool "Enable __must_check logic"
34    default y
35    help
36      Enable the __must_check logic in the kernel build. Disable this to
37      suppress the "warning: ignoring return value of 'foo', declared with
38      attribute warn_unused_result" messages.
39
40config FRAME_WARN
41    int "Warn for stack frames larger than (needs gcc 4.4)"
42    range 0 8192
43    default 1024 if !64BIT
44    default 2048 if 64BIT
45    help
46      Tell gcc to warn at build time for stack frames larger than this.
47      Setting this too low will cause a lot of warnings.
48      Setting it to 0 disables the warning.
49      Requires gcc 4.4
50
51config MAGIC_SYSRQ
52    bool "Magic SysRq key"
53    depends on !UML
54    help
55      If you say Y here, you will have some control over the system even
56      if the system crashes for example during kernel debugging (e.g., you
57      will be able to flush the buffer cache to disk, reboot the system
58      immediately or dump some status information). This is accomplished
59      by pressing various keys while holding SysRq (Alt+PrintScreen). It
60      also works on a serial console (on PC hardware at least), if you
61      send a BREAK and then within 5 seconds a command keypress. The
62      keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
63      unless you really know what this hack does.
64
65config STRIP_ASM_SYMS
66    bool "Strip assembler-generated symbols during link"
67    default n
68    help
69      Strip internal assembler-generated symbols during a link (symbols
70      that look like '.Lxxx') so they don't pollute the output of
71      get_wchan() and suchlike.
72
73config UNUSED_SYMBOLS
74    bool "Enable unused/obsolete exported symbols"
75    default y if X86
76    help
77      Unused but exported symbols make the kernel needlessly bigger. For
78      that reason most of these unused exports will soon be removed. This
79      option is provided temporarily to provide a transition period in case
80      some external kernel module needs one of these symbols anyway. If you
81      encounter such a case in your module, consider if you are actually
82      using the right API. (rationale: since nobody in the kernel is using
83      this in a module, there is a pretty good chance it's actually the
84      wrong interface to use). If you really need the symbol, please send a
85      mail to the linux kernel mailing list mentioning the symbol and why
86      you really need it, and what the merge plan to the mainline kernel for
87      your module is.
88
89config DEBUG_FS
90    bool "Debug Filesystem"
91    help
92      debugfs is a virtual file system that kernel developers use to put
93      debugging files into. Enable this option to be able to read and
94      write to these files.
95
96      For detailed documentation on the debugfs API, see
97      Documentation/DocBook/filesystems.
98
99      If unsure, say N.
100
101config HEADERS_CHECK
102    bool "Run 'make headers_check' when building vmlinux"
103    depends on !UML
104    help
105      This option will extract the user-visible kernel headers whenever
106      building the kernel, and will run basic sanity checks on them to
107      ensure that exported files do not attempt to include files which
108      were not exported, etc.
109
110      If you're making modifications to header files which are
111      relevant for userspace, say 'Y', and check the headers
112      exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
113      your build tree), to make sure they're suitable.
114
115config DEBUG_SECTION_MISMATCH
116    bool "Enable full Section mismatch analysis"
117    help
118      The section mismatch analysis checks if there are illegal
119      references from one section to another section.
120      During linktime or runtime, some sections are dropped;
121      any use of code/data previously in these sections would
122      most likely result in an oops.
123      In the code, functions and variables are annotated with
124      __init, __devinit, etc. (see the full list in include/linux/init.h),
125      which results in the code/data being placed in specific sections.
126      The section mismatch analysis is always performed after a full
127      kernel build, and enabling this option causes the following
128      additional steps to occur:
129      - Add the option -fno-inline-functions-called-once to gcc commands.
130        When inlining a function annotated with __init in a non-init
131        function, we would lose the section information and thus
132        the analysis would not catch the illegal reference.
133        This option tells gcc to inline less (but it does result in
134        a larger kernel).
135      - Run the section mismatch analysis for each module/built-in.o file.
136        When we run the section mismatch analysis on vmlinux.o, we
137        lose valueble information about where the mismatch was
138        introduced.
139        Running the analysis for each module/built-in.o file
140        tells where the mismatch happens much closer to the
141        source. The drawback is that the same mismatch is
142        reported at least twice.
143      - Enable verbose reporting from modpost in order to help resolve
144        the section mismatches that are reported.
145
146config DEBUG_KERNEL
147    bool "Kernel debugging"
148    help
149      Say Y here if you are developing drivers or trying to debug and
150      identify kernel problems.
151
152config DEBUG_SHIRQ
153    bool "Debug shared IRQ handlers"
154    depends on DEBUG_KERNEL && GENERIC_HARDIRQS
155    help
156      Enable this to generate a spurious interrupt as soon as a shared
157      interrupt handler is registered, and just before one is deregistered.
158      Drivers ought to be able to handle interrupts coming in at those
159      points; some don't and need to be caught.
160
161config LOCKUP_DETECTOR
162    bool "Detect Hard and Soft Lockups"
163    depends on DEBUG_KERNEL && !S390
164    help
165      Say Y here to enable the kernel to act as a watchdog to detect
166      hard and soft lockups.
167
168      Softlockups are bugs that cause the kernel to loop in kernel
169      mode for more than 60 seconds, without giving other tasks a
170      chance to run. The current stack trace is displayed upon
171      detection and the system will stay locked up.
172
173      Hardlockups are bugs that cause the CPU to loop in kernel mode
174      for more than 60 seconds, without letting other interrupts have a
175      chance to run. The current stack trace is displayed upon detection
176      and the system will stay locked up.
177
178      The overhead should be minimal. A periodic hrtimer runs to
179      generate interrupts and kick the watchdog task every 10-12 seconds.
180      An NMI is generated every 60 seconds or so to check for hardlockups.
181
182config HARDLOCKUP_DETECTOR
183    def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
184         !ARCH_HAS_NMI_WATCHDOG
185
186config BOOTPARAM_HARDLOCKUP_PANIC
187    bool "Panic (Reboot) On Hard Lockups"
188    depends on LOCKUP_DETECTOR
189    help
190      Say Y here to enable the kernel to panic on "hard lockups",
191      which are bugs that cause the kernel to loop in kernel
192      mode with interrupts disabled for more than 60 seconds.
193
194      Say N if unsure.
195
196config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
197    int
198    depends on LOCKUP_DETECTOR
199    range 0 1
200    default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
201    default 1 if BOOTPARAM_HARDLOCKUP_PANIC
202
203config BOOTPARAM_SOFTLOCKUP_PANIC
204    bool "Panic (Reboot) On Soft Lockups"
205    depends on LOCKUP_DETECTOR
206    help
207      Say Y here to enable the kernel to panic on "soft lockups",
208      which are bugs that cause the kernel to loop in kernel
209      mode for more than 60 seconds, without giving other tasks a
210      chance to run.
211
212      The panic can be used in combination with panic_timeout,
213      to cause the system to reboot automatically after a
214      lockup has been detected. This feature is useful for
215      high-availability systems that have uptime guarantees and
216      where a lockup must be resolved ASAP.
217
218      Say N if unsure.
219
220config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
221    int
222    depends on LOCKUP_DETECTOR
223    range 0 1
224    default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
225    default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
226
227config DETECT_HUNG_TASK
228    bool "Detect Hung Tasks"
229    depends on DEBUG_KERNEL
230    default LOCKUP_DETECTOR
231    help
232      Say Y here to enable the kernel to detect "hung tasks",
233      which are bugs that cause the task to be stuck in
234      uninterruptible "D" state indefinitiley.
235
236      When a hung task is detected, the kernel will print the
237      current stack trace (which you should report), but the
238      task will stay in uninterruptible state. If lockdep is
239      enabled then all held locks will also be reported. This
240      feature has negligible overhead.
241
242config DEFAULT_HUNG_TASK_TIMEOUT
243    int "Default timeout for hung task detection (in seconds)"
244    depends on DETECT_HUNG_TASK
245    default 120
246    help
247      This option controls the default timeout (in seconds) used
248      to determine when a task has become non-responsive and should
249      be considered hung.
250
251      It can be adjusted at runtime via the kernel.hung_task_timeout_secs
252      sysctl or by writing a value to
253      /proc/sys/kernel/hung_task_timeout_secs.
254
255      A timeout of 0 disables the check. The default is two minutes.
256      Keeping the default should be fine in most cases.
257
258config BOOTPARAM_HUNG_TASK_PANIC
259    bool "Panic (Reboot) On Hung Tasks"
260    depends on DETECT_HUNG_TASK
261    help
262      Say Y here to enable the kernel to panic on "hung tasks",
263      which are bugs that cause the kernel to leave a task stuck
264      in uninterruptible "D" state.
265
266      The panic can be used in combination with panic_timeout,
267      to cause the system to reboot automatically after a
268      hung task has been detected. This feature is useful for
269      high-availability systems that have uptime guarantees and
270      where a hung tasks must be resolved ASAP.
271
272      Say N if unsure.
273
274config BOOTPARAM_HUNG_TASK_PANIC_VALUE
275    int
276    depends on DETECT_HUNG_TASK
277    range 0 1
278    default 0 if !BOOTPARAM_HUNG_TASK_PANIC
279    default 1 if BOOTPARAM_HUNG_TASK_PANIC
280
281config SCHED_DEBUG
282    bool "Collect scheduler debugging info"
283    depends on DEBUG_KERNEL && PROC_FS
284    default y
285    help
286      If you say Y here, the /proc/sched_debug file will be provided
287      that can help debug the scheduler. The runtime overhead of this
288      option is minimal.
289
290config SCHEDSTATS
291    bool "Collect scheduler statistics"
292    depends on DEBUG_KERNEL && PROC_FS
293    help
294      If you say Y here, additional code will be inserted into the
295      scheduler and related routines to collect statistics about
296      scheduler behavior and provide them in /proc/schedstat. These
297      stats may be useful for both tuning and debugging the scheduler
298      If you aren't debugging the scheduler or trying to tune a specific
299      application, you can say N to avoid the very slight overhead
300      this adds.
301
302config TIMER_STATS
303    bool "Collect kernel timers statistics"
304    depends on DEBUG_KERNEL && PROC_FS
305    help
306      If you say Y here, additional code will be inserted into the
307      timer routines to collect statistics about kernel timers being
308      reprogrammed. The statistics can be read from /proc/timer_stats.
309      The statistics collection is started by writing 1 to /proc/timer_stats,
310      writing 0 stops it. This feature is useful to collect information
311      about timer usage patterns in kernel and userspace. This feature
312      is lightweight if enabled in the kernel config but not activated
313      (it defaults to deactivated on bootup and will only be activated
314      if some application like powertop activates it explicitly).
315
316config DEBUG_OBJECTS
317    bool "Debug object operations"
318    depends on DEBUG_KERNEL
319    help
320      If you say Y here, additional code will be inserted into the
321      kernel to track the life time of various objects and validate
322      the operations on those objects.
323
324config DEBUG_OBJECTS_SELFTEST
325    bool "Debug objects selftest"
326    depends on DEBUG_OBJECTS
327    help
328      This enables the selftest of the object debug code.
329
330config DEBUG_OBJECTS_FREE
331    bool "Debug objects in freed memory"
332    depends on DEBUG_OBJECTS
333    help
334      This enables checks whether a k/v free operation frees an area
335      which contains an object which has not been deactivated
336      properly. This can make kmalloc/kfree-intensive workloads
337      much slower.
338
339config DEBUG_OBJECTS_TIMERS
340    bool "Debug timer objects"
341    depends on DEBUG_OBJECTS
342    help
343      If you say Y here, additional code will be inserted into the
344      timer routines to track the life time of timer objects and
345      validate the timer operations.
346
347config DEBUG_OBJECTS_WORK
348    bool "Debug work objects"
349    depends on DEBUG_OBJECTS
350    help
351      If you say Y here, additional code will be inserted into the
352      work queue routines to track the life time of work objects and
353      validate the work operations.
354
355config DEBUG_OBJECTS_RCU_HEAD
356    bool "Debug RCU callbacks objects"
357    depends on DEBUG_OBJECTS
358    help
359      Enable this to turn on debugging of RCU list heads (call_rcu() usage).
360
361config DEBUG_OBJECTS_PERCPU_COUNTER
362    bool "Debug percpu counter objects"
363    depends on DEBUG_OBJECTS
364    help
365      If you say Y here, additional code will be inserted into the
366      percpu counter routines to track the life time of percpu counter
367      objects and validate the percpu counter operations.
368
369config DEBUG_OBJECTS_ENABLE_DEFAULT
370    int "debug_objects bootup default value (0-1)"
371        range 0 1
372        default "1"
373        depends on DEBUG_OBJECTS
374        help
375          Debug objects boot parameter default value
376
377config DEBUG_SLAB
378    bool "Debug slab memory allocations"
379    depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
380    help
381      Say Y here to have the kernel do limited verification on memory
382      allocation as well as poisoning memory on free to catch use of freed
383      memory. This can make kmalloc/kfree-intensive workloads much slower.
384
385config DEBUG_SLAB_LEAK
386    bool "Memory leak debugging"
387    depends on DEBUG_SLAB
388
389config SLUB_DEBUG_ON
390    bool "SLUB debugging on by default"
391    depends on SLUB && SLUB_DEBUG && !KMEMCHECK
392    default n
393    help
394      Boot with debugging on by default. SLUB boots by default with
395      the runtime debug capabilities switched off. Enabling this is
396      equivalent to specifying the "slub_debug" parameter on boot.
397      There is no support for more fine grained debug control like
398      possible with slub_debug=xxx. SLUB debugging may be switched
399      off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
400      "slub_debug=-".
401
402config SLUB_STATS
403    default n
404    bool "Enable SLUB performance statistics"
405    depends on SLUB && SYSFS
406    help
407      SLUB statistics are useful to debug SLUBs allocation behavior in
408      order find ways to optimize the allocator. This should never be
409      enabled for production use since keeping statistics slows down
410      the allocator by a few percentage points. The slabinfo command
411      supports the determination of the most active slabs to figure
412      out which slabs are relevant to a particular load.
413      Try running: slabinfo -DA
414
415config DEBUG_KMEMLEAK
416    bool "Kernel memory leak detector"
417    depends on DEBUG_KERNEL && EXPERIMENTAL && \
418        (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
419
420    select DEBUG_FS
421    select STACKTRACE if STACKTRACE_SUPPORT
422    select KALLSYMS
423    select CRC32
424    help
425      Say Y here if you want to enable the memory leak
426      detector. The memory allocation/freeing is traced in a way
427      similar to the Boehm's conservative garbage collector, the
428      difference being that the orphan objects are not freed but
429      only shown in /sys/kernel/debug/kmemleak. Enabling this
430      feature will introduce an overhead to memory
431      allocations. See Documentation/kmemleak.txt for more
432      details.
433
434      Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
435      of finding leaks due to the slab objects poisoning.
436
437      In order to access the kmemleak file, debugfs needs to be
438      mounted (usually at /sys/kernel/debug).
439
440config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
441    int "Maximum kmemleak early log entries"
442    depends on DEBUG_KMEMLEAK
443    range 200 40000
444    default 400
445    help
446      Kmemleak must track all the memory allocations to avoid
447      reporting false positives. Since memory may be allocated or
448      freed before kmemleak is initialised, an early log buffer is
449      used to store these actions. If kmemleak reports "early log
450      buffer exceeded", please increase this value.
451
452config DEBUG_KMEMLEAK_TEST
453    tristate "Simple test for the kernel memory leak detector"
454    depends on DEBUG_KMEMLEAK && m
455    help
456      This option enables a module that explicitly leaks memory.
457
458      If unsure, say N.
459
460config DEBUG_KMEMLEAK_DEFAULT_OFF
461    bool "Default kmemleak to off"
462    depends on DEBUG_KMEMLEAK
463    help
464      Say Y here to disable kmemleak by default. It can then be enabled
465      on the command line via kmemleak=on.
466
467config DEBUG_PREEMPT
468    bool "Debug preemptible kernel"
469    depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
470    default y
471    help
472      If you say Y here then the kernel will use a debug variant of the
473      commonly used smp_processor_id() function and will print warnings
474      if kernel code uses it in a preemption-unsafe way. Also, the kernel
475      will detect preemption count underflows.
476
477config DEBUG_RT_MUTEXES
478    bool "RT Mutex debugging, deadlock detection"
479    depends on DEBUG_KERNEL && RT_MUTEXES
480    help
481     This allows rt mutex semantics violations and rt mutex related
482     deadlocks (lockups) to be detected and reported automatically.
483
484config DEBUG_PI_LIST
485    bool
486    default y
487    depends on DEBUG_RT_MUTEXES
488
489config RT_MUTEX_TESTER
490    bool "Built-in scriptable tester for rt-mutexes"
491    depends on DEBUG_KERNEL && RT_MUTEXES
492    help
493      This option enables a rt-mutex tester.
494
495config DEBUG_SPINLOCK
496    bool "Spinlock and rw-lock debugging: basic checks"
497    depends on DEBUG_KERNEL
498    help
499      Say Y here and build SMP to catch missing spinlock initialization
500      and certain other kinds of spinlock errors commonly made. This is
501      best used in conjunction with the NMI watchdog so that spinlock
502      deadlocks are also debuggable.
503
504config DEBUG_MUTEXES
505    bool "Mutex debugging: basic checks"
506    depends on DEBUG_KERNEL
507    help
508     This feature allows mutex semantics violations to be detected and
509     reported.
510
511config DEBUG_LOCK_ALLOC
512    bool "Lock debugging: detect incorrect freeing of live locks"
513    depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
514    select DEBUG_SPINLOCK
515    select DEBUG_MUTEXES
516    select LOCKDEP
517    help
518     This feature will check whether any held lock (spinlock, rwlock,
519     mutex or rwsem) is incorrectly freed by the kernel, via any of the
520     memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
521     vfree(), etc.), whether a live lock is incorrectly reinitialized via
522     spin_lock_init()/mutex_init()/etc., or whether there is any lock
523     held during task exit.
524
525config PROVE_LOCKING
526    bool "Lock debugging: prove locking correctness"
527    depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
528    select LOCKDEP
529    select DEBUG_SPINLOCK
530    select DEBUG_MUTEXES
531    select DEBUG_LOCK_ALLOC
532    select TRACE_IRQFLAGS
533    default n
534    help
535     This feature enables the kernel to prove that all locking
536     that occurs in the kernel runtime is mathematically
537     correct: that under no circumstance could an arbitrary (and
538     not yet triggered) combination of observed locking
539     sequences (on an arbitrary number of CPUs, running an
540     arbitrary number of tasks and interrupt contexts) cause a
541     deadlock.
542
543     In short, this feature enables the kernel to report locking
544     related deadlocks before they actually occur.
545
546     The proof does not depend on how hard and complex a
547     deadlock scenario would be to trigger: how many
548     participant CPUs, tasks and irq-contexts would be needed
549     for it to trigger. The proof also does not depend on
550     timing: if a race and a resulting deadlock is possible
551     theoretically (no matter how unlikely the race scenario
552     is), it will be proven so and will immediately be
553     reported by the kernel (once the event is observed that
554     makes the deadlock theoretically possible).
555
556     If a deadlock is impossible (i.e. the locking rules, as
557     observed by the kernel, are mathematically correct), the
558     kernel reports nothing.
559
560     NOTE: this feature can also be enabled for rwlocks, mutexes
561     and rwsems - in which case all dependencies between these
562     different locking variants are observed and mapped too, and
563     the proof of observed correctness is also maintained for an
564     arbitrary combination of these separate locking variants.
565
566     For more details, see Documentation/lockdep-design.txt.
567
568config PROVE_RCU
569    bool "RCU debugging: prove RCU correctness"
570    depends on PROVE_LOCKING
571    default n
572    help
573     This feature enables lockdep extensions that check for correct
574     use of RCU APIs. This is currently under development. Say Y
575     if you want to debug RCU usage or help work on the PROVE_RCU
576     feature.
577
578     Say N if you are unsure.
579
580config PROVE_RCU_REPEATEDLY
581    bool "RCU debugging: don't disable PROVE_RCU on first splat"
582    depends on PROVE_RCU
583    default n
584    help
585     By itself, PROVE_RCU will disable checking upon issuing the
586     first warning (or "splat"). This feature prevents such
587     disabling, allowing multiple RCU-lockdep warnings to be printed
588     on a single reboot.
589
590     Say Y to allow multiple RCU-lockdep warnings per boot.
591
592     Say N if you are unsure.
593
594config SPARSE_RCU_POINTER
595    bool "RCU debugging: sparse-based checks for pointer usage"
596    default n
597    help
598     This feature enables the __rcu sparse annotation for
599     RCU-protected pointers. This annotation will cause sparse
600     to flag any non-RCU used of annotated pointers. This can be
601     helpful when debugging RCU usage. Please note that this feature
602     is not intended to enforce code cleanliness; it is instead merely
603     a debugging aid.
604
605     Say Y to make sparse flag questionable use of RCU-protected pointers
606
607     Say N if you are unsure.
608
609config LOCKDEP
610    bool
611    depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
612    select STACKTRACE
613    select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
614    select KALLSYMS
615    select KALLSYMS_ALL
616
617config LOCK_STAT
618    bool "Lock usage statistics"
619    depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
620    select LOCKDEP
621    select DEBUG_SPINLOCK
622    select DEBUG_MUTEXES
623    select DEBUG_LOCK_ALLOC
624    default n
625    help
626     This feature enables tracking lock contention points
627
628     For more details, see Documentation/lockstat.txt
629
630     This also enables lock events required by "perf lock",
631     subcommand of perf.
632     If you want to use "perf lock", you also need to turn on
633     CONFIG_EVENT_TRACING.
634
635     CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
636     (CONFIG_LOCKDEP defines "acquire" and "release" events.)
637
638config DEBUG_LOCKDEP
639    bool "Lock dependency engine debugging"
640    depends on DEBUG_KERNEL && LOCKDEP
641    help
642      If you say Y here, the lock dependency engine will do
643      additional runtime checks to debug itself, at the price
644      of more runtime overhead.
645
646config TRACE_IRQFLAGS
647    bool
648    help
649      Enables hooks to interrupt enabling and disabling for
650      either tracing or lock debugging.
651
652config DEBUG_ATOMIC_SLEEP
653    bool "Sleep inside atomic section checking"
654    select PREEMPT_COUNT
655    depends on DEBUG_KERNEL
656    help
657      If you say Y here, various routines which may sleep will become very
658      noisy if they are called inside atomic sections: when a spinlock is
659      held, inside an rcu read side critical section, inside preempt disabled
660      sections, inside an interrupt, etc...
661
662config DEBUG_LOCKING_API_SELFTESTS
663    bool "Locking API boot-time self-tests"
664    depends on DEBUG_KERNEL
665    help
666      Say Y here if you want the kernel to run a short self-test during
667      bootup. The self-test checks whether common types of locking bugs
668      are detected by debugging mechanisms or not. (if you disable
669      lock debugging then those bugs wont be detected of course.)
670      The following locking APIs are covered: spinlocks, rwlocks,
671      mutexes and rwsems.
672
673config STACKTRACE
674    bool
675    depends on STACKTRACE_SUPPORT
676
677config DEBUG_STACK_USAGE
678    bool "Stack utilization instrumentation"
679    depends on DEBUG_KERNEL
680    help
681      Enables the display of the minimum amount of free stack which each
682      task has ever had available in the sysrq-T and sysrq-P debug output.
683
684      This option will slow down process creation somewhat.
685
686config DEBUG_KOBJECT
687    bool "kobject debugging"
688    depends on DEBUG_KERNEL
689    help
690      If you say Y here, some extra kobject debugging messages will be sent
691      to the syslog.
692
693config DEBUG_HIGHMEM
694    bool "Highmem debugging"
695    depends on DEBUG_KERNEL && HIGHMEM
696    help
697      This options enables addition error checking for high memory systems.
698      Disable for production systems.
699
700config DEBUG_BUGVERBOSE
701    bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
702    depends on BUG
703    depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
704           FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || TILE
705    default y
706    help
707      Say Y here to make BUG() panics output the file name and line number
708      of the BUG call as well as the EIP and oops trace. This aids
709      debugging but costs about 70-100K of memory.
710
711config DEBUG_INFO
712    bool "Compile the kernel with debug info"
713    depends on DEBUG_KERNEL
714    help
715          If you say Y here the resulting kernel image will include
716      debugging info resulting in a larger kernel image.
717      This adds debug symbols to the kernel and modules (gcc -g), and
718      is needed if you intend to use kernel crashdump or binary object
719      tools like crash, kgdb, LKCD, gdb, etc on the kernel.
720      Say Y here only if you plan to debug the kernel.
721
722      If unsure, say N.
723
724config DEBUG_INFO_REDUCED
725    bool "Reduce debugging information"
726    depends on DEBUG_INFO
727    help
728      If you say Y here gcc is instructed to generate less debugging
729      information for structure types. This means that tools that
730      need full debugging information (like kgdb or systemtap) won't
731      be happy. But if you merely need debugging information to
732      resolve line numbers there is no loss. Advantage is that
733      build directory object sizes shrink dramatically over a full
734      DEBUG_INFO build and compile times are reduced too.
735      Only works with newer gcc versions.
736
737config DEBUG_VM
738    bool "Debug VM"
739    depends on DEBUG_KERNEL
740    help
741      Enable this to turn on extended checks in the virtual-memory system
742          that may impact performance.
743
744      If unsure, say N.
745
746config DEBUG_VIRTUAL
747    bool "Debug VM translations"
748    depends on DEBUG_KERNEL && X86
749    help
750      Enable some costly sanity checks in virtual to page code. This can
751      catch mistakes with virt_to_page() and friends.
752
753      If unsure, say N.
754
755config DEBUG_NOMMU_REGIONS
756    bool "Debug the global anon/private NOMMU mapping region tree"
757    depends on DEBUG_KERNEL && !MMU
758    help
759      This option causes the global tree of anonymous and private mapping
760      regions to be regularly checked for invalid topology.
761
762config DEBUG_WRITECOUNT
763    bool "Debug filesystem writers count"
764    depends on DEBUG_KERNEL
765    help
766      Enable this to catch wrong use of the writers count in struct
767      vfsmount. This will increase the size of each file struct by
768      32 bits.
769
770      If unsure, say N.
771
772config DEBUG_MEMORY_INIT
773    bool "Debug memory initialisation" if EXPERT
774    default !EXPERT
775    help
776      Enable this for additional checks during memory initialisation.
777      The sanity checks verify aspects of the VM such as the memory model
778      and other information provided by the architecture. Verbose
779      information will be printed at KERN_DEBUG loglevel depending
780      on the mminit_loglevel= command-line option.
781
782      If unsure, say Y
783
784config DEBUG_LIST
785    bool "Debug linked list manipulation"
786    depends on DEBUG_KERNEL
787    help
788      Enable this to turn on extended checks in the linked-list
789      walking routines.
790
791      If unsure, say N.
792
793config TEST_LIST_SORT
794    bool "Linked list sorting test"
795    depends on DEBUG_KERNEL
796    help
797      Enable this to turn on 'list_sort()' function test. This test is
798      executed only once during system boot, so affects only boot time.
799
800      If unsure, say N.
801
802config DEBUG_SG
803    bool "Debug SG table operations"
804    depends on DEBUG_KERNEL
805    help
806      Enable this to turn on checks on scatter-gather tables. This can
807      help find problems with drivers that do not properly initialize
808      their sg tables.
809
810      If unsure, say N.
811
812config DEBUG_NOTIFIERS
813    bool "Debug notifier call chains"
814    depends on DEBUG_KERNEL
815    help
816      Enable this to turn on sanity checking for notifier call chains.
817      This is most useful for kernel developers to make sure that
818      modules properly unregister themselves from notifier chains.
819      This is a relatively cheap check but if you care about maximum
820      performance, say N.
821
822config DEBUG_CREDENTIALS
823    bool "Debug credential management"
824    depends on DEBUG_KERNEL
825    help
826      Enable this to turn on some debug checking for credential
827      management. The additional code keeps track of the number of
828      pointers from task_structs to any given cred struct, and checks to
829      see that this number never exceeds the usage count of the cred
830      struct.
831
832      Furthermore, if SELinux is enabled, this also checks that the
833      security pointer in the cred struct is never seen to be invalid.
834
835      If unsure, say N.
836
837#
838# Select this config option from the architecture Kconfig, if it
839# is preferred to always offer frame pointers as a config
840# option on the architecture (regardless of KERNEL_DEBUG):
841#
842config ARCH_WANT_FRAME_POINTERS
843    bool
844    help
845
846config FRAME_POINTER
847    bool "Compile the kernel with frame pointers"
848    depends on DEBUG_KERNEL && \
849        (CRIS || M68K || FRV || UML || \
850         AVR32 || SUPERH || BLACKFIN || MN10300) || \
851        ARCH_WANT_FRAME_POINTERS
852    default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
853    help
854      If you say Y here the resulting kernel image will be slightly
855      larger and slower, but it gives very useful debugging information
856      in case of kernel bugs. (precise oopses/stacktraces/warnings)
857
858config BOOT_PRINTK_DELAY
859    bool "Delay each boot printk message by N milliseconds"
860    depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
861    help
862      This build option allows you to read kernel boot messages
863      by inserting a short delay after each one. The delay is
864      specified in milliseconds on the kernel command line,
865      using "boot_delay=N".
866
867      It is likely that you would also need to use "lpj=M" to preset
868      the "loops per jiffie" value.
869      See a previous boot log for the "lpj" value to use for your
870      system, and then set "lpj=M" before setting "boot_delay=N".
871      NOTE: Using this option may adversely affect SMP systems.
872      I.e., processors other than the first one may not boot up.
873      BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
874      what it believes to be lockup conditions.
875
876config RCU_TORTURE_TEST
877    tristate "torture tests for RCU"
878    depends on DEBUG_KERNEL
879    default n
880    help
881      This option provides a kernel module that runs torture tests
882      on the RCU infrastructure. The kernel module may be built
883      after the fact on the running kernel to be tested, if desired.
884
885      Say Y here if you want RCU torture tests to be built into
886      the kernel.
887      Say M if you want the RCU torture tests to build as a module.
888      Say N if you are unsure.
889
890config RCU_TORTURE_TEST_RUNNABLE
891    bool "torture tests for RCU runnable by default"
892    depends on RCU_TORTURE_TEST = y
893    default n
894    help
895      This option provides a way to build the RCU torture tests
896      directly into the kernel without them starting up at boot
897      time. You can use /proc/sys/kernel/rcutorture_runnable
898      to manually override this setting. This /proc file is
899      available only when the RCU torture tests have been built
900      into the kernel.
901
902      Say Y here if you want the RCU torture tests to start during
903      boot (you probably don't).
904      Say N here if you want the RCU torture tests to start only
905      after being manually enabled via /proc.
906
907config RCU_CPU_STALL_TIMEOUT
908    int "RCU CPU stall timeout in seconds"
909    depends on TREE_RCU || TREE_PREEMPT_RCU
910    range 3 300
911    default 60
912    help
913      If a given RCU grace period extends more than the specified
914      number of seconds, a CPU stall warning is printed. If the
915      RCU grace period persists, additional CPU stall warnings are
916      printed at more widely spaced intervals.
917
918config RCU_CPU_STALL_VERBOSE
919    bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
920    depends on TREE_PREEMPT_RCU
921    default y
922    help
923      This option causes RCU to printk detailed per-task information
924      for any tasks that are stalling the current RCU grace period.
925
926      Say N if you are unsure.
927
928      Say Y if you want to enable such checks.
929
930config KPROBES_SANITY_TEST
931    bool "Kprobes sanity tests"
932    depends on DEBUG_KERNEL
933    depends on KPROBES
934    default n
935    help
936      This option provides for testing basic kprobes functionality on
937      boot. A sample kprobe, jprobe and kretprobe are inserted and
938      verified for functionality.
939
940      Say N if you are unsure.
941
942config BACKTRACE_SELF_TEST
943    tristate "Self test for the backtrace code"
944    depends on DEBUG_KERNEL
945    default n
946    help
947      This option provides a kernel module that can be used to test
948      the kernel stack backtrace code. This option is not useful
949      for distributions or general kernels, but only for kernel
950      developers working on architecture code.
951
952      Note that if you want to also test saved backtraces, you will
953      have to enable STACKTRACE as well.
954
955      Say N if you are unsure.
956
957config DEBUG_BLOCK_EXT_DEVT
958        bool "Force extended block device numbers and spread them"
959    depends on DEBUG_KERNEL
960    depends on BLOCK
961    default n
962    help
963      BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
964      SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
965      YOU ARE DOING. Distros, please enable this and fix whatever
966      is broken.
967
968      Conventionally, block device numbers are allocated from
969      predetermined contiguous area. However, extended block area
970      may introduce non-contiguous block device numbers. This
971      option forces most block device numbers to be allocated from
972      the extended space and spreads them to discover kernel or
973      userland code paths which assume predetermined contiguous
974      device number allocation.
975
976      Note that turning on this debug option shuffles all the
977      device numbers for all IDE and SCSI devices including libata
978      ones, so root partition specified using device number
979      directly (via rdev or root=MAJ:MIN) won't work anymore.
980      Textual device names (root=/dev/sdXn) will continue to work.
981
982      Say N if you are unsure.
983
984config DEBUG_FORCE_WEAK_PER_CPU
985    bool "Force weak per-cpu definitions"
986    depends on DEBUG_KERNEL
987    help
988      s390 and alpha require percpu variables in modules to be
989      defined weak to work around addressing range issue which
990      puts the following two restrictions on percpu variable
991      definitions.
992
993      1. percpu symbols must be unique whether static or not
994      2. percpu variables can't be defined inside a function
995
996      To ensure that generic code follows the above rules, this
997      option forces all percpu variables to be defined as weak.
998
999config DEBUG_PER_CPU_MAPS
1000    bool "Debug access to per_cpu maps"
1001    depends on DEBUG_KERNEL
1002    depends on SMP
1003    help
1004      Say Y to verify that the per_cpu map being accessed has
1005      been set up. This adds a fair amount of code to kernel memory
1006      and decreases performance.
1007
1008      Say N if unsure.
1009
1010config LKDTM
1011    tristate "Linux Kernel Dump Test Tool Module"
1012    depends on DEBUG_FS
1013    depends on BLOCK
1014    default n
1015    help
1016    This module enables testing of the different dumping mechanisms by
1017    inducing system failures at predefined crash points.
1018    If you don't need it: say N
1019    Choose M here to compile this code as a module. The module will be
1020    called lkdtm.
1021
1022    Documentation on how to use the module can be found in
1023    Documentation/fault-injection/provoke-crashes.txt
1024
1025config CPU_NOTIFIER_ERROR_INJECT
1026    tristate "CPU notifier error injection module"
1027    depends on HOTPLUG_CPU && DEBUG_KERNEL
1028    help
1029      This option provides a kernel module that can be used to test
1030      the error handling of the cpu notifiers
1031
1032      To compile this code as a module, choose M here: the module will
1033      be called cpu-notifier-error-inject.
1034
1035      If unsure, say N.
1036
1037config FAULT_INJECTION
1038    bool "Fault-injection framework"
1039    depends on DEBUG_KERNEL
1040    help
1041      Provide fault-injection framework.
1042      For more details, see Documentation/fault-injection/.
1043
1044config FAILSLAB
1045    bool "Fault-injection capability for kmalloc"
1046    depends on FAULT_INJECTION
1047    depends on SLAB || SLUB
1048    help
1049      Provide fault-injection capability for kmalloc.
1050
1051config FAIL_PAGE_ALLOC
1052    bool "Fault-injection capabilitiy for alloc_pages()"
1053    depends on FAULT_INJECTION
1054    help
1055      Provide fault-injection capability for alloc_pages().
1056
1057config FAIL_MAKE_REQUEST
1058    bool "Fault-injection capability for disk IO"
1059    depends on FAULT_INJECTION && BLOCK
1060    help
1061      Provide fault-injection capability for disk IO.
1062
1063config FAIL_IO_TIMEOUT
1064    bool "Fault-injection capability for faking disk interrupts"
1065    depends on FAULT_INJECTION && BLOCK
1066    help
1067      Provide fault-injection capability on end IO handling. This
1068      will make the block layer "forget" an interrupt as configured,
1069      thus exercising the error handling.
1070
1071      Only works with drivers that use the generic timeout handling,
1072      for others it wont do anything.
1073
1074config FAIL_MMC_REQUEST
1075    bool "Fault-injection capability for MMC IO"
1076    select DEBUG_FS
1077    depends on FAULT_INJECTION && MMC
1078    help
1079      Provide fault-injection capability for MMC IO.
1080      This will make the mmc core return data errors. This is
1081      useful to test the error handling in the mmc block device
1082      and to test how the mmc host driver handles retries from
1083      the block device.
1084
1085config FAULT_INJECTION_DEBUG_FS
1086    bool "Debugfs entries for fault-injection capabilities"
1087    depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1088    help
1089      Enable configuration of fault-injection capabilities via debugfs.
1090
1091config FAULT_INJECTION_STACKTRACE_FILTER
1092    bool "stacktrace filter for fault-injection capabilities"
1093    depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1094    depends on !X86_64
1095    select STACKTRACE
1096    select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1097    help
1098      Provide stacktrace filter for fault-injection capabilities
1099
1100config LATENCYTOP
1101    bool "Latency measuring infrastructure"
1102    depends on HAVE_LATENCYTOP_SUPPORT
1103    depends on DEBUG_KERNEL
1104    depends on STACKTRACE_SUPPORT
1105    depends on PROC_FS
1106    select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1107    select KALLSYMS
1108    select KALLSYMS_ALL
1109    select STACKTRACE
1110    select SCHEDSTATS
1111    select SCHED_DEBUG
1112    help
1113      Enable this option if you want to use the LatencyTOP tool
1114      to find out which userspace is blocking on what kernel operations.
1115
1116config SYSCTL_SYSCALL_CHECK
1117    bool "Sysctl checks"
1118    depends on SYSCTL
1119    ---help---
1120      sys_sysctl uses binary paths that have been found challenging
1121      to properly maintain and use. This enables checks that help
1122      you to keep things correct.
1123
1124source mm/Kconfig.debug
1125source kernel/trace/Kconfig
1126
1127config PROVIDE_OHCI1394_DMA_INIT
1128    bool "Remote debugging over FireWire early on boot"
1129    depends on PCI && X86
1130    help
1131      If you want to debug problems which hang or crash the kernel early
1132      on boot and the crashing machine has a FireWire port, you can use
1133      this feature to remotely access the memory of the crashed machine
1134      over FireWire. This employs remote DMA as part of the OHCI1394
1135      specification which is now the standard for FireWire controllers.
1136
1137      With remote DMA, you can monitor the printk buffer remotely using
1138      firescope and access all memory below 4GB using fireproxy from gdb.
1139      Even controlling a kernel debugger is possible using remote DMA.
1140
1141      Usage:
1142
1143      If ohci1394_dma=early is used as boot parameter, it will initialize
1144      all OHCI1394 controllers which are found in the PCI config space.
1145
1146      As all changes to the FireWire bus such as enabling and disabling
1147      devices cause a bus reset and thereby disable remote DMA for all
1148      devices, be sure to have the cable plugged and FireWire enabled on
1149      the debugging host before booting the debug target for debugging.
1150
1151      This code (~1k) is freed after boot. By then, the firewire stack
1152      in charge of the OHCI-1394 controllers should be used instead.
1153
1154      See Documentation/debugging-via-ohci1394.txt for more information.
1155
1156config FIREWIRE_OHCI_REMOTE_DMA
1157    bool "Remote debugging over FireWire with firewire-ohci"
1158    depends on FIREWIRE_OHCI
1159    help
1160      This option lets you use the FireWire bus for remote debugging
1161      with help of the firewire-ohci driver. It enables unfiltered
1162      remote DMA in firewire-ohci.
1163      See Documentation/debugging-via-ohci1394.txt for more information.
1164
1165      If unsure, say N.
1166
1167config BUILD_DOCSRC
1168    bool "Build targets in Documentation/ tree"
1169    depends on HEADERS_CHECK
1170    help
1171      This option attempts to build objects from the source files in the
1172      kernel Documentation/ tree.
1173
1174      Say N if you are unsure.
1175
1176config DYNAMIC_DEBUG
1177    bool "Enable dynamic printk() support"
1178    default n
1179    depends on PRINTK
1180    depends on DEBUG_FS
1181    help
1182
1183      Compiles debug level messages into the kernel, which would not
1184      otherwise be available at runtime. These messages can then be
1185      enabled/disabled based on various levels of scope - per source file,
1186      function, module, format string, and line number. This mechanism
1187      implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1188      this compile option is a larger kernel text size of about 2%.
1189
1190      Usage:
1191
1192      Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1193      which is contained in the 'debugfs' filesystem. Thus, the debugfs
1194      filesystem must first be mounted before making use of this feature.
1195      We refer the control file as: <debugfs>/dynamic_debug/control. This
1196      file contains a list of the debug statements that can be enabled. The
1197      format for each line of the file is:
1198
1199        filename:lineno [module]function flags format
1200
1201      filename : source file of the debug statement
1202      lineno : line number of the debug statement
1203      module : module that contains the debug statement
1204      function : function that contains the debug statement
1205          flags : 'p' means the line is turned 'on' for printing
1206          format : the format used for the debug statement
1207
1208      From a live system:
1209
1210        nullarbor:~ # cat <debugfs>/dynamic_debug/control
1211        # filename:lineno [module]function flags format
1212        fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1213        fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1214        fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1215
1216      Example usage:
1217
1218        // enable the message at line 1603 of file svcsock.c
1219        nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1220                        <debugfs>/dynamic_debug/control
1221
1222        // enable all the messages in file svcsock.c
1223        nullarbor:~ # echo -n 'file svcsock.c +p' >
1224                        <debugfs>/dynamic_debug/control
1225
1226        // enable all the messages in the NFS server module
1227        nullarbor:~ # echo -n 'module nfsd +p' >
1228                        <debugfs>/dynamic_debug/control
1229
1230        // enable all 12 messages in the function svc_process()
1231        nullarbor:~ # echo -n 'func svc_process +p' >
1232                        <debugfs>/dynamic_debug/control
1233
1234        // disable all 12 messages in the function svc_process()
1235        nullarbor:~ # echo -n 'func svc_process -p' >
1236                        <debugfs>/dynamic_debug/control
1237
1238      See Documentation/dynamic-debug-howto.txt for additional information.
1239
1240config DMA_API_DEBUG
1241    bool "Enable debugging of DMA-API usage"
1242    depends on HAVE_DMA_API_DEBUG
1243    help
1244      Enable this option to debug the use of the DMA API by device drivers.
1245      With this option you will be able to detect common bugs in device
1246      drivers like double-freeing of DMA mappings or freeing mappings that
1247      were never allocated.
1248      This option causes a performance degredation. Use only if you want
1249      to debug device drivers. If unsure, say N.
1250
1251config ATOMIC64_SELFTEST
1252    bool "Perform an atomic64_t self-test at boot"
1253    help
1254      Enable this option to test the atomic64_t functions at boot.
1255
1256      If unsure, say N.
1257
1258config ASYNC_RAID6_TEST
1259    tristate "Self test for hardware accelerated raid6 recovery"
1260    depends on ASYNC_RAID6_RECOV
1261    select ASYNC_MEMCPY
1262    ---help---
1263      This is a one-shot self test that permutes through the
1264      recovery of all the possible two disk failure scenarios for a
1265      N-disk array. Recovery is performed with the asynchronous
1266      raid6 recovery routines, and will optionally use an offload
1267      engine if one is available.
1268
1269      If unsure, say N.
1270
1271source "samples/Kconfig"
1272
1273source "lib/Kconfig.kgdb"
1274
1275source "lib/Kconfig.kmemcheck"
1276
1277config TEST_KSTRTOX
1278    tristate "Test kstrto*() family of functions at runtime"
1279

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