Root/lib/Kconfig.debug

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.
11
12config ENABLE_WARN_DEPRECATED
13    bool "Enable __deprecated logic"
14    default y
15    help
16      Enable the __deprecated logic in the kernel build.
17      Disable this to suppress the "warning: 'foo' is deprecated
18      (declared at kernel/power/somefile.c:1234)" messages.
19
20config ENABLE_MUST_CHECK
21    bool "Enable __must_check logic"
22    default y
23    help
24      Enable the __must_check logic in the kernel build. Disable this to
25      suppress the "warning: ignoring return value of 'foo', declared with
26      attribute warn_unused_result" messages.
27
28config FRAME_WARN
29    int "Warn for stack frames larger than (needs gcc 4.4)"
30    range 0 8192
31    default 1024 if !64BIT
32    default 2048 if 64BIT
33    help
34      Tell gcc to warn at build time for stack frames larger than this.
35      Setting this too low will cause a lot of warnings.
36      Setting it to 0 disables the warning.
37      Requires gcc 4.4
38
39config MAGIC_SYSRQ
40    bool "Magic SysRq key"
41    depends on !UML
42    help
43      If you say Y here, you will have some control over the system even
44      if the system crashes for example during kernel debugging (e.g., you
45      will be able to flush the buffer cache to disk, reboot the system
46      immediately or dump some status information). This is accomplished
47      by pressing various keys while holding SysRq (Alt+PrintScreen). It
48      also works on a serial console (on PC hardware at least), if you
49      send a BREAK and then within 5 seconds a command keypress. The
50      keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
51      unless you really know what this hack does.
52
53config STRIP_ASM_SYMS
54    bool "Strip assembler-generated symbols during link"
55    default n
56    help
57      Strip internal assembler-generated symbols during a link (symbols
58      that look like '.Lxxx') so they don't pollute the output of
59      get_wchan() and suchlike.
60
61config UNUSED_SYMBOLS
62    bool "Enable unused/obsolete exported symbols"
63    default y if X86
64    help
65      Unused but exported symbols make the kernel needlessly bigger. For
66      that reason most of these unused exports will soon be removed. This
67      option is provided temporarily to provide a transition period in case
68      some external kernel module needs one of these symbols anyway. If you
69      encounter such a case in your module, consider if you are actually
70      using the right API. (rationale: since nobody in the kernel is using
71      this in a module, there is a pretty good chance it's actually the
72      wrong interface to use). If you really need the symbol, please send a
73      mail to the linux kernel mailing list mentioning the symbol and why
74      you really need it, and what the merge plan to the mainline kernel for
75      your module is.
76
77config DEBUG_FS
78    bool "Debug Filesystem"
79    depends on SYSFS
80    help
81      debugfs is a virtual file system that kernel developers use to put
82      debugging files into. Enable this option to be able to read and
83      write to these files.
84
85      For detailed documentation on the debugfs API, see
86      Documentation/DocBook/filesystems.
87
88      If unsure, say N.
89
90config HEADERS_CHECK
91    bool "Run 'make headers_check' when building vmlinux"
92    depends on !UML
93    help
94      This option will extract the user-visible kernel headers whenever
95      building the kernel, and will run basic sanity checks on them to
96      ensure that exported files do not attempt to include files which
97      were not exported, etc.
98
99      If you're making modifications to header files which are
100      relevant for userspace, say 'Y', and check the headers
101      exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
102      your build tree), to make sure they're suitable.
103
104config DEBUG_SECTION_MISMATCH
105    bool "Enable full Section mismatch analysis"
106    depends on UNDEFINED || (BLACKFIN)
107    default y
108    # This option is on purpose disabled for now.
109    # It will be enabled when we are down to a reasonable number
110    # of section mismatch warnings (< 10 for an allyesconfig build)
111    help
112      The section mismatch analysis checks if there are illegal
113      references from one section to another section.
114      Linux will during link or during runtime drop some sections
115      and any use of code/data previously in these sections will
116      most likely result in an oops.
117      In the code functions and variables are annotated with
118      __init, __devinit etc. (see full list in include/linux/init.h)
119      which results in the code/data being placed in specific sections.
120      The section mismatch analysis is always done after a full
121      kernel build but enabling this option will in addition
122      do the following:
123      - Add the option -fno-inline-functions-called-once to gcc
124        When inlining a function annotated __init in a non-init
125        function we would lose the section information and thus
126        the analysis would not catch the illegal reference.
127        This option tells gcc to inline less but will also
128        result in a larger kernel.
129      - Run the section mismatch analysis for each module/built-in.o
130        When we run the section mismatch analysis on vmlinux.o we
131        lose valueble information about where the mismatch was
132        introduced.
133        Running the analysis for each module/built-in.o file
134        will tell where the mismatch happens much closer to the
135        source. The drawback is that we will report the same
136        mismatch at least twice.
137      - Enable verbose reporting from modpost to help solving
138        the section mismatches reported.
139
140config DEBUG_KERNEL
141    bool "Kernel debugging"
142    help
143      Say Y here if you are developing drivers or trying to debug and
144      identify kernel problems.
145
146config DEBUG_SHIRQ
147    bool "Debug shared IRQ handlers"
148    depends on DEBUG_KERNEL && GENERIC_HARDIRQS
149    help
150      Enable this to generate a spurious interrupt as soon as a shared
151      interrupt handler is registered, and just before one is deregistered.
152      Drivers ought to be able to handle interrupts coming in at those
153      points; some don't and need to be caught.
154
155config DETECT_SOFTLOCKUP
156    bool "Detect Soft Lockups"
157    depends on DEBUG_KERNEL && !S390
158    default y
159    help
160      Say Y here to enable the kernel to detect "soft lockups",
161      which are bugs that cause the kernel to loop in kernel
162      mode for more than 60 seconds, without giving other tasks a
163      chance to run.
164
165      When a soft-lockup is detected, the kernel will print the
166      current stack trace (which you should report), but the
167      system will stay locked up. This feature has negligible
168      overhead.
169
170      (Note that "hard lockups" are separate type of bugs that
171       can be detected via the NMI-watchdog, on platforms that
172       support it.)
173
174config BOOTPARAM_SOFTLOCKUP_PANIC
175    bool "Panic (Reboot) On Soft Lockups"
176    depends on DETECT_SOFTLOCKUP
177    help
178      Say Y here to enable the kernel to panic on "soft lockups",
179      which are bugs that cause the kernel to loop in kernel
180      mode for more than 60 seconds, without giving other tasks a
181      chance to run.
182
183      The panic can be used in combination with panic_timeout,
184      to cause the system to reboot automatically after a
185      lockup has been detected. This feature is useful for
186      high-availability systems that have uptime guarantees and
187      where a lockup must be resolved ASAP.
188
189      Say N if unsure.
190
191config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
192    int
193    depends on DETECT_SOFTLOCKUP
194    range 0 1
195    default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
196    default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
197
198config DETECT_HUNG_TASK
199    bool "Detect Hung Tasks"
200    depends on DEBUG_KERNEL
201    default DETECT_SOFTLOCKUP
202    help
203      Say Y here to enable the kernel to detect "hung tasks",
204      which are bugs that cause the task to be stuck in
205      uninterruptible "D" state indefinitiley.
206
207      When a hung task is detected, the kernel will print the
208      current stack trace (which you should report), but the
209      task will stay in uninterruptible state. If lockdep is
210      enabled then all held locks will also be reported. This
211      feature has negligible overhead.
212
213config BOOTPARAM_HUNG_TASK_PANIC
214    bool "Panic (Reboot) On Hung Tasks"
215    depends on DETECT_HUNG_TASK
216    help
217      Say Y here to enable the kernel to panic on "hung tasks",
218      which are bugs that cause the kernel to leave a task stuck
219      in uninterruptible "D" state.
220
221      The panic can be used in combination with panic_timeout,
222      to cause the system to reboot automatically after a
223      hung task has been detected. This feature is useful for
224      high-availability systems that have uptime guarantees and
225      where a hung tasks must be resolved ASAP.
226
227      Say N if unsure.
228
229config BOOTPARAM_HUNG_TASK_PANIC_VALUE
230    int
231    depends on DETECT_HUNG_TASK
232    range 0 1
233    default 0 if !BOOTPARAM_HUNG_TASK_PANIC
234    default 1 if BOOTPARAM_HUNG_TASK_PANIC
235
236config SCHED_DEBUG
237    bool "Collect scheduler debugging info"
238    depends on DEBUG_KERNEL && PROC_FS
239    default y
240    help
241      If you say Y here, the /proc/sched_debug file will be provided
242      that can help debug the scheduler. The runtime overhead of this
243      option is minimal.
244
245config SCHEDSTATS
246    bool "Collect scheduler statistics"
247    depends on DEBUG_KERNEL && PROC_FS
248    help
249      If you say Y here, additional code will be inserted into the
250      scheduler and related routines to collect statistics about
251      scheduler behavior and provide them in /proc/schedstat. These
252      stats may be useful for both tuning and debugging the scheduler
253      If you aren't debugging the scheduler or trying to tune a specific
254      application, you can say N to avoid the very slight overhead
255      this adds.
256
257config TIMER_STATS
258    bool "Collect kernel timers statistics"
259    depends on DEBUG_KERNEL && PROC_FS
260    help
261      If you say Y here, additional code will be inserted into the
262      timer routines to collect statistics about kernel timers being
263      reprogrammed. The statistics can be read from /proc/timer_stats.
264      The statistics collection is started by writing 1 to /proc/timer_stats,
265      writing 0 stops it. This feature is useful to collect information
266      about timer usage patterns in kernel and userspace. This feature
267      is lightweight if enabled in the kernel config but not activated
268      (it defaults to deactivated on bootup and will only be activated
269      if some application like powertop activates it explicitly).
270
271config DEBUG_OBJECTS
272    bool "Debug object operations"
273    depends on DEBUG_KERNEL
274    help
275      If you say Y here, additional code will be inserted into the
276      kernel to track the life time of various objects and validate
277      the operations on those objects.
278
279config DEBUG_OBJECTS_SELFTEST
280    bool "Debug objects selftest"
281    depends on DEBUG_OBJECTS
282    help
283      This enables the selftest of the object debug code.
284
285config DEBUG_OBJECTS_FREE
286    bool "Debug objects in freed memory"
287    depends on DEBUG_OBJECTS
288    help
289      This enables checks whether a k/v free operation frees an area
290      which contains an object which has not been deactivated
291      properly. This can make kmalloc/kfree-intensive workloads
292      much slower.
293
294config DEBUG_OBJECTS_TIMERS
295    bool "Debug timer objects"
296    depends on DEBUG_OBJECTS
297    help
298      If you say Y here, additional code will be inserted into the
299      timer routines to track the life time of timer objects and
300      validate the timer operations.
301
302config DEBUG_OBJECTS_WORK
303    bool "Debug work objects"
304    depends on DEBUG_OBJECTS
305    help
306      If you say Y here, additional code will be inserted into the
307      work queue routines to track the life time of work objects and
308      validate the work operations.
309
310config DEBUG_OBJECTS_ENABLE_DEFAULT
311    int "debug_objects bootup default value (0-1)"
312        range 0 1
313        default "1"
314        depends on DEBUG_OBJECTS
315        help
316          Debug objects boot parameter default value
317
318config DEBUG_SLAB
319    bool "Debug slab memory allocations"
320    depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
321    help
322      Say Y here to have the kernel do limited verification on memory
323      allocation as well as poisoning memory on free to catch use of freed
324      memory. This can make kmalloc/kfree-intensive workloads much slower.
325
326config DEBUG_SLAB_LEAK
327    bool "Memory leak debugging"
328    depends on DEBUG_SLAB
329
330config SLUB_DEBUG_ON
331    bool "SLUB debugging on by default"
332    depends on SLUB && SLUB_DEBUG && !KMEMCHECK
333    default n
334    help
335      Boot with debugging on by default. SLUB boots by default with
336      the runtime debug capabilities switched off. Enabling this is
337      equivalent to specifying the "slub_debug" parameter on boot.
338      There is no support for more fine grained debug control like
339      possible with slub_debug=xxx. SLUB debugging may be switched
340      off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
341      "slub_debug=-".
342
343config SLUB_STATS
344    default n
345    bool "Enable SLUB performance statistics"
346    depends on SLUB && SLUB_DEBUG && SYSFS
347    help
348      SLUB statistics are useful to debug SLUBs allocation behavior in
349      order find ways to optimize the allocator. This should never be
350      enabled for production use since keeping statistics slows down
351      the allocator by a few percentage points. The slabinfo command
352      supports the determination of the most active slabs to figure
353      out which slabs are relevant to a particular load.
354      Try running: slabinfo -DA
355
356config DEBUG_KMEMLEAK
357    bool "Kernel memory leak detector"
358    depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
359        (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE)
360
361    select DEBUG_FS if SYSFS
362    select STACKTRACE if STACKTRACE_SUPPORT
363    select KALLSYMS
364    select CRC32
365    help
366      Say Y here if you want to enable the memory leak
367      detector. The memory allocation/freeing is traced in a way
368      similar to the Boehm's conservative garbage collector, the
369      difference being that the orphan objects are not freed but
370      only shown in /sys/kernel/debug/kmemleak. Enabling this
371      feature will introduce an overhead to memory
372      allocations. See Documentation/kmemleak.txt for more
373      details.
374
375      Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
376      of finding leaks due to the slab objects poisoning.
377
378      In order to access the kmemleak file, debugfs needs to be
379      mounted (usually at /sys/kernel/debug).
380
381config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
382    int "Maximum kmemleak early log entries"
383    depends on DEBUG_KMEMLEAK
384    range 200 40000
385    default 400
386    help
387      Kmemleak must track all the memory allocations to avoid
388      reporting false positives. Since memory may be allocated or
389      freed before kmemleak is initialised, an early log buffer is
390      used to store these actions. If kmemleak reports "early log
391      buffer exceeded", please increase this value.
392
393config DEBUG_KMEMLEAK_TEST
394    tristate "Simple test for the kernel memory leak detector"
395    depends on DEBUG_KMEMLEAK
396    help
397      Say Y or M here to build a test for the kernel memory leak
398      detector. This option enables a module that explicitly leaks
399      memory.
400
401      If unsure, say N.
402
403config DEBUG_PREEMPT
404    bool "Debug preemptible kernel"
405    depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
406    default y
407    help
408      If you say Y here then the kernel will use a debug variant of the
409      commonly used smp_processor_id() function and will print warnings
410      if kernel code uses it in a preemption-unsafe way. Also, the kernel
411      will detect preemption count underflows.
412
413config DEBUG_RT_MUTEXES
414    bool "RT Mutex debugging, deadlock detection"
415    depends on DEBUG_KERNEL && RT_MUTEXES
416    help
417     This allows rt mutex semantics violations and rt mutex related
418     deadlocks (lockups) to be detected and reported automatically.
419
420config DEBUG_PI_LIST
421    bool
422    default y
423    depends on DEBUG_RT_MUTEXES
424
425config RT_MUTEX_TESTER
426    bool "Built-in scriptable tester for rt-mutexes"
427    depends on DEBUG_KERNEL && RT_MUTEXES
428    help
429      This option enables a rt-mutex tester.
430
431config DEBUG_SPINLOCK
432    bool "Spinlock and rw-lock debugging: basic checks"
433    depends on DEBUG_KERNEL
434    help
435      Say Y here and build SMP to catch missing spinlock initialization
436      and certain other kinds of spinlock errors commonly made. This is
437      best used in conjunction with the NMI watchdog so that spinlock
438      deadlocks are also debuggable.
439
440config DEBUG_MUTEXES
441    bool "Mutex debugging: basic checks"
442    depends on DEBUG_KERNEL
443    help
444     This feature allows mutex semantics violations to be detected and
445     reported.
446
447config DEBUG_LOCK_ALLOC
448    bool "Lock debugging: detect incorrect freeing of live locks"
449    depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
450    select DEBUG_SPINLOCK
451    select DEBUG_MUTEXES
452    select LOCKDEP
453    help
454     This feature will check whether any held lock (spinlock, rwlock,
455     mutex or rwsem) is incorrectly freed by the kernel, via any of the
456     memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
457     vfree(), etc.), whether a live lock is incorrectly reinitialized via
458     spin_lock_init()/mutex_init()/etc., or whether there is any lock
459     held during task exit.
460
461config PROVE_LOCKING
462    bool "Lock debugging: prove locking correctness"
463    depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
464    select LOCKDEP
465    select DEBUG_SPINLOCK
466    select DEBUG_MUTEXES
467    select DEBUG_LOCK_ALLOC
468    default n
469    help
470     This feature enables the kernel to prove that all locking
471     that occurs in the kernel runtime is mathematically
472     correct: that under no circumstance could an arbitrary (and
473     not yet triggered) combination of observed locking
474     sequences (on an arbitrary number of CPUs, running an
475     arbitrary number of tasks and interrupt contexts) cause a
476     deadlock.
477
478     In short, this feature enables the kernel to report locking
479     related deadlocks before they actually occur.
480
481     The proof does not depend on how hard and complex a
482     deadlock scenario would be to trigger: how many
483     participant CPUs, tasks and irq-contexts would be needed
484     for it to trigger. The proof also does not depend on
485     timing: if a race and a resulting deadlock is possible
486     theoretically (no matter how unlikely the race scenario
487     is), it will be proven so and will immediately be
488     reported by the kernel (once the event is observed that
489     makes the deadlock theoretically possible).
490
491     If a deadlock is impossible (i.e. the locking rules, as
492     observed by the kernel, are mathematically correct), the
493     kernel reports nothing.
494
495     NOTE: this feature can also be enabled for rwlocks, mutexes
496     and rwsems - in which case all dependencies between these
497     different locking variants are observed and mapped too, and
498     the proof of observed correctness is also maintained for an
499     arbitrary combination of these separate locking variants.
500
501     For more details, see Documentation/lockdep-design.txt.
502
503config PROVE_RCU
504    bool "RCU debugging: prove RCU correctness"
505    depends on PROVE_LOCKING
506    default n
507    help
508     This feature enables lockdep extensions that check for correct
509     use of RCU APIs. This is currently under development. Say Y
510     if you want to debug RCU usage or help work on the PROVE_RCU
511     feature.
512
513     Say N if you are unsure.
514
515config LOCKDEP
516    bool
517    depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
518    select STACKTRACE
519    select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
520    select KALLSYMS
521    select KALLSYMS_ALL
522
523config LOCK_STAT
524    bool "Lock usage statistics"
525    depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
526    select LOCKDEP
527    select DEBUG_SPINLOCK
528    select DEBUG_MUTEXES
529    select DEBUG_LOCK_ALLOC
530    default n
531    help
532     This feature enables tracking lock contention points
533
534     For more details, see Documentation/lockstat.txt
535
536     This also enables lock events required by "perf lock",
537     subcommand of perf.
538     If you want to use "perf lock", you also need to turn on
539     CONFIG_EVENT_TRACING.
540
541     CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
542     (CONFIG_LOCKDEP defines "acquire" and "release" events.)
543
544config DEBUG_LOCKDEP
545    bool "Lock dependency engine debugging"
546    depends on DEBUG_KERNEL && LOCKDEP
547    help
548      If you say Y here, the lock dependency engine will do
549      additional runtime checks to debug itself, at the price
550      of more runtime overhead.
551
552config TRACE_IRQFLAGS
553    depends on DEBUG_KERNEL
554    bool
555    default y
556    depends on TRACE_IRQFLAGS_SUPPORT
557    depends on PROVE_LOCKING
558
559config DEBUG_SPINLOCK_SLEEP
560    bool "Spinlock debugging: sleep-inside-spinlock checking"
561    depends on DEBUG_KERNEL
562    help
563      If you say Y here, various routines which may sleep will become very
564      noisy if they are called with a spinlock held.
565
566config DEBUG_LOCKING_API_SELFTESTS
567    bool "Locking API boot-time self-tests"
568    depends on DEBUG_KERNEL
569    help
570      Say Y here if you want the kernel to run a short self-test during
571      bootup. The self-test checks whether common types of locking bugs
572      are detected by debugging mechanisms or not. (if you disable
573      lock debugging then those bugs wont be detected of course.)
574      The following locking APIs are covered: spinlocks, rwlocks,
575      mutexes and rwsems.
576
577config STACKTRACE
578    bool
579    depends on STACKTRACE_SUPPORT
580
581config DEBUG_KOBJECT
582    bool "kobject debugging"
583    depends on DEBUG_KERNEL
584    help
585      If you say Y here, some extra kobject debugging messages will be sent
586      to the syslog.
587
588config DEBUG_HIGHMEM
589    bool "Highmem debugging"
590    depends on DEBUG_KERNEL && HIGHMEM
591    help
592      This options enables addition error checking for high memory systems.
593      Disable for production systems.
594
595config DEBUG_BUGVERBOSE
596    bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
597    depends on BUG
598    depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
599           FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
600    default y
601    help
602      Say Y here to make BUG() panics output the file name and line number
603      of the BUG call as well as the EIP and oops trace. This aids
604      debugging but costs about 70-100K of memory.
605
606config DEBUG_INFO
607    bool "Compile the kernel with debug info"
608    depends on DEBUG_KERNEL
609    help
610          If you say Y here the resulting kernel image will include
611      debugging info resulting in a larger kernel image.
612      This adds debug symbols to the kernel and modules (gcc -g), and
613      is needed if you intend to use kernel crashdump or binary object
614      tools like crash, kgdb, LKCD, gdb, etc on the kernel.
615      Say Y here only if you plan to debug the kernel.
616
617      If unsure, say N.
618
619config DEBUG_VM
620    bool "Debug VM"
621    depends on DEBUG_KERNEL
622    help
623      Enable this to turn on extended checks in the virtual-memory system
624          that may impact performance.
625
626      If unsure, say N.
627
628config DEBUG_VIRTUAL
629    bool "Debug VM translations"
630    depends on DEBUG_KERNEL && X86
631    help
632      Enable some costly sanity checks in virtual to page code. This can
633      catch mistakes with virt_to_page() and friends.
634
635      If unsure, say N.
636
637config DEBUG_NOMMU_REGIONS
638    bool "Debug the global anon/private NOMMU mapping region tree"
639    depends on DEBUG_KERNEL && !MMU
640    help
641      This option causes the global tree of anonymous and private mapping
642      regions to be regularly checked for invalid topology.
643
644config DEBUG_WRITECOUNT
645    bool "Debug filesystem writers count"
646    depends on DEBUG_KERNEL
647    help
648      Enable this to catch wrong use of the writers count in struct
649      vfsmount. This will increase the size of each file struct by
650      32 bits.
651
652      If unsure, say N.
653
654config DEBUG_MEMORY_INIT
655    bool "Debug memory initialisation" if EMBEDDED
656    default !EMBEDDED
657    help
658      Enable this for additional checks during memory initialisation.
659      The sanity checks verify aspects of the VM such as the memory model
660      and other information provided by the architecture. Verbose
661      information will be printed at KERN_DEBUG loglevel depending
662      on the mminit_loglevel= command-line option.
663
664      If unsure, say Y
665
666config DEBUG_LIST
667    bool "Debug linked list manipulation"
668    depends on DEBUG_KERNEL
669    help
670      Enable this to turn on extended checks in the linked-list
671      walking routines.
672
673      If unsure, say N.
674
675config DEBUG_SG
676    bool "Debug SG table operations"
677    depends on DEBUG_KERNEL
678    help
679      Enable this to turn on checks on scatter-gather tables. This can
680      help find problems with drivers that do not properly initialize
681      their sg tables.
682
683      If unsure, say N.
684
685config DEBUG_NOTIFIERS
686    bool "Debug notifier call chains"
687    depends on DEBUG_KERNEL
688    help
689      Enable this to turn on sanity checking for notifier call chains.
690      This is most useful for kernel developers to make sure that
691      modules properly unregister themselves from notifier chains.
692      This is a relatively cheap check but if you care about maximum
693      performance, say N.
694
695config DEBUG_CREDENTIALS
696    bool "Debug credential management"
697    depends on DEBUG_KERNEL
698    help
699      Enable this to turn on some debug checking for credential
700      management. The additional code keeps track of the number of
701      pointers from task_structs to any given cred struct, and checks to
702      see that this number never exceeds the usage count of the cred
703      struct.
704
705      Furthermore, if SELinux is enabled, this also checks that the
706      security pointer in the cred struct is never seen to be invalid.
707
708      If unsure, say N.
709
710#
711# Select this config option from the architecture Kconfig, if it
712# it is preferred to always offer frame pointers as a config
713# option on the architecture (regardless of KERNEL_DEBUG):
714#
715config ARCH_WANT_FRAME_POINTERS
716    bool
717    help
718
719config FRAME_POINTER
720    bool "Compile the kernel with frame pointers"
721    depends on DEBUG_KERNEL && \
722        (CRIS || M68K || M68KNOMMU || FRV || UML || \
723         AVR32 || SUPERH || BLACKFIN || MN10300) || \
724        ARCH_WANT_FRAME_POINTERS
725    default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
726    help
727      If you say Y here the resulting kernel image will be slightly
728      larger and slower, but it gives very useful debugging information
729      in case of kernel bugs. (precise oopses/stacktraces/warnings)
730
731config BOOT_PRINTK_DELAY
732    bool "Delay each boot printk message by N milliseconds"
733    depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
734    help
735      This build option allows you to read kernel boot messages
736      by inserting a short delay after each one. The delay is
737      specified in milliseconds on the kernel command line,
738      using "boot_delay=N".
739
740      It is likely that you would also need to use "lpj=M" to preset
741      the "loops per jiffie" value.
742      See a previous boot log for the "lpj" value to use for your
743      system, and then set "lpj=M" before setting "boot_delay=N".
744      NOTE: Using this option may adversely affect SMP systems.
745      I.e., processors other than the first one may not boot up.
746      BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
747      what it believes to be lockup conditions.
748
749config RCU_TORTURE_TEST
750    tristate "torture tests for RCU"
751    depends on DEBUG_KERNEL
752    default n
753    help
754      This option provides a kernel module that runs torture tests
755      on the RCU infrastructure. The kernel module may be built
756      after the fact on the running kernel to be tested, if desired.
757
758      Say Y here if you want RCU torture tests to be built into
759      the kernel.
760      Say M if you want the RCU torture tests to build as a module.
761      Say N if you are unsure.
762
763config RCU_TORTURE_TEST_RUNNABLE
764    bool "torture tests for RCU runnable by default"
765    depends on RCU_TORTURE_TEST = y
766    default n
767    help
768      This option provides a way to build the RCU torture tests
769      directly into the kernel without them starting up at boot
770      time. You can use /proc/sys/kernel/rcutorture_runnable
771      to manually override this setting. This /proc file is
772      available only when the RCU torture tests have been built
773      into the kernel.
774
775      Say Y here if you want the RCU torture tests to start during
776      boot (you probably don't).
777      Say N here if you want the RCU torture tests to start only
778      after being manually enabled via /proc.
779
780config RCU_CPU_STALL_DETECTOR
781    bool "Check for stalled CPUs delaying RCU grace periods"
782    depends on TREE_RCU || TREE_PREEMPT_RCU
783    default y
784    help
785      This option causes RCU to printk information on which
786      CPUs are delaying the current grace period, but only when
787      the grace period extends for excessive time periods.
788
789      Say N if you want to disable such checks.
790
791      Say Y if you are unsure.
792
793config RCU_CPU_STALL_VERBOSE
794    bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
795    depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
796    default n
797    help
798      This option causes RCU to printk detailed per-task information
799      for any tasks that are stalling the current RCU grace period.
800
801      Say N if you are unsure.
802
803      Say Y if you want to enable such checks.
804
805config KPROBES_SANITY_TEST
806    bool "Kprobes sanity tests"
807    depends on DEBUG_KERNEL
808    depends on KPROBES
809    default n
810    help
811      This option provides for testing basic kprobes functionality on
812      boot. A sample kprobe, jprobe and kretprobe are inserted and
813      verified for functionality.
814
815      Say N if you are unsure.
816
817config BACKTRACE_SELF_TEST
818    tristate "Self test for the backtrace code"
819    depends on DEBUG_KERNEL
820    default n
821    help
822      This option provides a kernel module that can be used to test
823      the kernel stack backtrace code. This option is not useful
824      for distributions or general kernels, but only for kernel
825      developers working on architecture code.
826
827      Note that if you want to also test saved backtraces, you will
828      have to enable STACKTRACE as well.
829
830      Say N if you are unsure.
831
832config DEBUG_BLOCK_EXT_DEVT
833        bool "Force extended block device numbers and spread them"
834    depends on DEBUG_KERNEL
835    depends on BLOCK
836    default n
837    help
838      BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
839      SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
840      YOU ARE DOING. Distros, please enable this and fix whatever
841      is broken.
842
843      Conventionally, block device numbers are allocated from
844      predetermined contiguous area. However, extended block area
845      may introduce non-contiguous block device numbers. This
846      option forces most block device numbers to be allocated from
847      the extended space and spreads them to discover kernel or
848      userland code paths which assume predetermined contiguous
849      device number allocation.
850
851      Note that turning on this debug option shuffles all the
852      device numbers for all IDE and SCSI devices including libata
853      ones, so root partition specified using device number
854      directly (via rdev or root=MAJ:MIN) won't work anymore.
855      Textual device names (root=/dev/sdXn) will continue to work.
856
857      Say N if you are unsure.
858
859config DEBUG_FORCE_WEAK_PER_CPU
860    bool "Force weak per-cpu definitions"
861    depends on DEBUG_KERNEL
862    help
863      s390 and alpha require percpu variables in modules to be
864      defined weak to work around addressing range issue which
865      puts the following two restrictions on percpu variable
866      definitions.
867
868      1. percpu symbols must be unique whether static or not
869      2. percpu variables can't be defined inside a function
870
871      To ensure that generic code follows the above rules, this
872      option forces all percpu variables to be defined as weak.
873
874config LKDTM
875    tristate "Linux Kernel Dump Test Tool Module"
876    depends on DEBUG_FS
877    depends on BLOCK
878    default n
879    help
880    This module enables testing of the different dumping mechanisms by
881    inducing system failures at predefined crash points.
882    If you don't need it: say N
883    Choose M here to compile this code as a module. The module will be
884    called lkdtm.
885
886    Documentation on how to use the module can be found in
887    Documentation/fault-injection/provoke-crashes.txt
888
889config FAULT_INJECTION
890    bool "Fault-injection framework"
891    depends on DEBUG_KERNEL
892    help
893      Provide fault-injection framework.
894      For more details, see Documentation/fault-injection/.
895
896config FAILSLAB
897    bool "Fault-injection capability for kmalloc"
898    depends on FAULT_INJECTION
899    depends on SLAB || SLUB
900    help
901      Provide fault-injection capability for kmalloc.
902
903config FAIL_PAGE_ALLOC
904    bool "Fault-injection capabilitiy for alloc_pages()"
905    depends on FAULT_INJECTION
906    help
907      Provide fault-injection capability for alloc_pages().
908
909config FAIL_MAKE_REQUEST
910    bool "Fault-injection capability for disk IO"
911    depends on FAULT_INJECTION && BLOCK
912    help
913      Provide fault-injection capability for disk IO.
914
915config FAIL_IO_TIMEOUT
916    bool "Faul-injection capability for faking disk interrupts"
917    depends on FAULT_INJECTION && BLOCK
918    help
919      Provide fault-injection capability on end IO handling. This
920      will make the block layer "forget" an interrupt as configured,
921      thus exercising the error handling.
922
923      Only works with drivers that use the generic timeout handling,
924      for others it wont do anything.
925
926config FAULT_INJECTION_DEBUG_FS
927    bool "Debugfs entries for fault-injection capabilities"
928    depends on FAULT_INJECTION && SYSFS && DEBUG_FS
929    help
930      Enable configuration of fault-injection capabilities via debugfs.
931
932config FAULT_INJECTION_STACKTRACE_FILTER
933    bool "stacktrace filter for fault-injection capabilities"
934    depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
935    depends on !X86_64
936    select STACKTRACE
937    select FRAME_POINTER if !PPC && !S390
938    help
939      Provide stacktrace filter for fault-injection capabilities
940
941config LATENCYTOP
942    bool "Latency measuring infrastructure"
943    select FRAME_POINTER if !MIPS && !PPC && !S390
944    select KALLSYMS
945    select KALLSYMS_ALL
946    select STACKTRACE
947    select SCHEDSTATS
948    select SCHED_DEBUG
949    depends on HAVE_LATENCYTOP_SUPPORT
950    help
951      Enable this option if you want to use the LatencyTOP tool
952      to find out which userspace is blocking on what kernel operations.
953
954config SYSCTL_SYSCALL_CHECK
955    bool "Sysctl checks"
956    depends on SYSCTL
957    ---help---
958      sys_sysctl uses binary paths that have been found challenging
959      to properly maintain and use. This enables checks that help
960      you to keep things correct.
961
962source mm/Kconfig.debug
963source kernel/trace/Kconfig
964
965config PROVIDE_OHCI1394_DMA_INIT
966    bool "Remote debugging over FireWire early on boot"
967    depends on PCI && X86
968    help
969      If you want to debug problems which hang or crash the kernel early
970      on boot and the crashing machine has a FireWire port, you can use
971      this feature to remotely access the memory of the crashed machine
972      over FireWire. This employs remote DMA as part of the OHCI1394
973      specification which is now the standard for FireWire controllers.
974
975      With remote DMA, you can monitor the printk buffer remotely using
976      firescope and access all memory below 4GB using fireproxy from gdb.
977      Even controlling a kernel debugger is possible using remote DMA.
978
979      Usage:
980
981      If ohci1394_dma=early is used as boot parameter, it will initialize
982      all OHCI1394 controllers which are found in the PCI config space.
983
984      As all changes to the FireWire bus such as enabling and disabling
985      devices cause a bus reset and thereby disable remote DMA for all
986      devices, be sure to have the cable plugged and FireWire enabled on
987      the debugging host before booting the debug target for debugging.
988
989      This code (~1k) is freed after boot. By then, the firewire stack
990      in charge of the OHCI-1394 controllers should be used instead.
991
992      See Documentation/debugging-via-ohci1394.txt for more information.
993
994config FIREWIRE_OHCI_REMOTE_DMA
995    bool "Remote debugging over FireWire with firewire-ohci"
996    depends on FIREWIRE_OHCI
997    help
998      This option lets you use the FireWire bus for remote debugging
999      with help of the firewire-ohci driver. It enables unfiltered
1000      remote DMA in firewire-ohci.
1001      See Documentation/debugging-via-ohci1394.txt for more information.
1002
1003      If unsure, say N.
1004
1005config BUILD_DOCSRC
1006    bool "Build targets in Documentation/ tree"
1007    depends on HEADERS_CHECK
1008    help
1009      This option attempts to build objects from the source files in the
1010      kernel Documentation/ tree.
1011
1012      Say N if you are unsure.
1013
1014config DYNAMIC_DEBUG
1015    bool "Enable dynamic printk() support"
1016    default n
1017    depends on PRINTK
1018    depends on DEBUG_FS
1019    help
1020
1021      Compiles debug level messages into the kernel, which would not
1022      otherwise be available at runtime. These messages can then be
1023      enabled/disabled based on various levels of scope - per source file,
1024      function, module, format string, and line number. This mechanism
1025      implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1026      this compile option is a larger kernel text size of about 2%.
1027
1028      Usage:
1029
1030      Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
1031      which is contained in the 'debugfs' filesystem. Thus, the debugfs
1032      filesystem must first be mounted before making use of this feature.
1033      We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
1034      file contains a list of the debug statements that can be enabled. The
1035      format for each line of the file is:
1036
1037        filename:lineno [module]function flags format
1038
1039      filename : source file of the debug statement
1040      lineno : line number of the debug statement
1041      module : module that contains the debug statement
1042      function : function that contains the debug statement
1043          flags : 'p' means the line is turned 'on' for printing
1044          format : the format used for the debug statement
1045
1046      From a live system:
1047
1048        nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
1049        # filename:lineno [module]function flags format
1050        fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1051        fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1052        fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1053
1054      Example usage:
1055
1056        // enable the message at line 1603 of file svcsock.c
1057        nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1058                        <debugfs>/dynamic_debug/ddebug
1059
1060        // enable all the messages in file svcsock.c
1061        nullarbor:~ # echo -n 'file svcsock.c +p' >
1062                        <debugfs>/dynamic_debug/ddebug
1063
1064        // enable all the messages in the NFS server module
1065        nullarbor:~ # echo -n 'module nfsd +p' >
1066                        <debugfs>/dynamic_debug/ddebug
1067
1068        // enable all 12 messages in the function svc_process()
1069        nullarbor:~ # echo -n 'func svc_process +p' >
1070                        <debugfs>/dynamic_debug/ddebug
1071
1072        // disable all 12 messages in the function svc_process()
1073        nullarbor:~ # echo -n 'func svc_process -p' >
1074                        <debugfs>/dynamic_debug/ddebug
1075
1076      See Documentation/dynamic-debug-howto.txt for additional information.
1077
1078config DMA_API_DEBUG
1079    bool "Enable debugging of DMA-API usage"
1080    depends on HAVE_DMA_API_DEBUG
1081    help
1082      Enable this option to debug the use of the DMA API by device drivers.
1083      With this option you will be able to detect common bugs in device
1084      drivers like double-freeing of DMA mappings or freeing mappings that
1085      were never allocated.
1086      This option causes a performance degredation. Use only if you want
1087      to debug device drivers. If unsure, say N.
1088
1089source "samples/Kconfig"
1090
1091source "lib/Kconfig.kgdb"
1092
1093source "lib/Kconfig.kmemcheck"
1094

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