linux/lib/Kconfig.debug
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   1
   2config PRINTK_TIME
   3        bool "Show timing information on printks"
   4        depends on PRINTK
   5        help
   6          Selecting this option causes time stamps of the printk()
   7          messages to be added to the output of the syslog() system
   8          call and at the console.
   9
  10          The timestamp is always recorded internally, and exported
  11          to /dev/kmsg. This flag just specifies if the timestamp should
  12          be included, not that the timestamp is recorded.
  13
  14          The behavior is also controlled by the kernel command line
  15          parameter printk.time=1. See Documentation/kernel-parameters.txt
  16
  17config DEFAULT_MESSAGE_LOGLEVEL
  18        int "Default message log level (1-7)"
  19        range 1 7
  20        default "4"
  21        help
  22          Default log level for printk statements with no specified priority.
  23
  24          This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
  25          that are auditing their logs closely may want to set it to a lower
  26          priority.
  27
  28config ENABLE_WARN_DEPRECATED
  29        bool "Enable __deprecated logic"
  30        default y
  31        help
  32          Enable the __deprecated logic in the kernel build.
  33          Disable this to suppress the "warning: 'foo' is deprecated
  34          (declared at kernel/power/somefile.c:1234)" messages.
  35
  36config ENABLE_MUST_CHECK
  37        bool "Enable __must_check logic"
  38        default y
  39        help
  40          Enable the __must_check logic in the kernel build.  Disable this to
  41          suppress the "warning: ignoring return value of 'foo', declared with
  42          attribute warn_unused_result" messages.
  43
  44config FRAME_WARN
  45        int "Warn for stack frames larger than (needs gcc 4.4)"
  46        range 0 8192
  47        default 1024 if !64BIT
  48        default 2048 if 64BIT
  49        help
  50          Tell gcc to warn at build time for stack frames larger than this.
  51          Setting this too low will cause a lot of warnings.
  52          Setting it to 0 disables the warning.
  53          Requires gcc 4.4
  54
  55config MAGIC_SYSRQ
  56        bool "Magic SysRq key"
  57        depends on !UML
  58        help
  59          If you say Y here, you will have some control over the system even
  60          if the system crashes for example during kernel debugging (e.g., you
  61          will be able to flush the buffer cache to disk, reboot the system
  62          immediately or dump some status information). This is accomplished
  63          by pressing various keys while holding SysRq (Alt+PrintScreen). It
  64          also works on a serial console (on PC hardware at least), if you
  65          send a BREAK and then within 5 seconds a command keypress. The
  66          keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  67          unless you really know what this hack does.
  68
  69config STRIP_ASM_SYMS
  70        bool "Strip assembler-generated symbols during link"
  71        default n
  72        help
  73          Strip internal assembler-generated symbols during a link (symbols
  74          that look like '.Lxxx') so they don't pollute the output of
  75          get_wchan() and suchlike.
  76
  77config READABLE_ASM
  78        bool "Generate readable assembler code"
  79        depends on DEBUG_KERNEL
  80        help
  81          Disable some compiler optimizations that tend to generate human unreadable
  82          assembler output. This may make the kernel slightly slower, but it helps
  83          to keep kernel developers who have to stare a lot at assembler listings
  84          sane.
  85
  86config UNUSED_SYMBOLS
  87        bool "Enable unused/obsolete exported symbols"
  88        default y if X86
  89        help
  90          Unused but exported symbols make the kernel needlessly bigger.  For
  91          that reason most of these unused exports will soon be removed.  This
  92          option is provided temporarily to provide a transition period in case
  93          some external kernel module needs one of these symbols anyway. If you
  94          encounter such a case in your module, consider if you are actually
  95          using the right API.  (rationale: since nobody in the kernel is using
  96          this in a module, there is a pretty good chance it's actually the
  97          wrong interface to use).  If you really need the symbol, please send a
  98          mail to the linux kernel mailing list mentioning the symbol and why
  99          you really need it, and what the merge plan to the mainline kernel for
 100          your module is.
 101
 102config DEBUG_FS
 103        bool "Debug Filesystem"
 104        help
 105          debugfs is a virtual file system that kernel developers use to put
 106          debugging files into.  Enable this option to be able to read and
 107          write to these files.
 108
 109          For detailed documentation on the debugfs API, see
 110          Documentation/DocBook/filesystems.
 111
 112          If unsure, say N.
 113
 114config HEADERS_CHECK
 115        bool "Run 'make headers_check' when building vmlinux"
 116        depends on !UML
 117        help
 118          This option will extract the user-visible kernel headers whenever
 119          building the kernel, and will run basic sanity checks on them to
 120          ensure that exported files do not attempt to include files which
 121          were not exported, etc.
 122
 123          If you're making modifications to header files which are
 124          relevant for userspace, say 'Y', and check the headers
 125          exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 126          your build tree), to make sure they're suitable.
 127
 128config DEBUG_SECTION_MISMATCH
 129        bool "Enable full Section mismatch analysis"
 130        help
 131          The section mismatch analysis checks if there are illegal
 132          references from one section to another section.
 133          During linktime or runtime, some sections are dropped;
 134          any use of code/data previously in these sections would
 135          most likely result in an oops.
 136          In the code, functions and variables are annotated with
 137          __init, __devinit, etc. (see the full list in include/linux/init.h),
 138          which results in the code/data being placed in specific sections.
 139          The section mismatch analysis is always performed after a full
 140          kernel build, and enabling this option causes the following
 141          additional steps to occur:
 142          - Add the option -fno-inline-functions-called-once to gcc commands.
 143            When inlining a function annotated with __init in a non-init
 144            function, we would lose the section information and thus
 145            the analysis would not catch the illegal reference.
 146            This option tells gcc to inline less (but it does result in
 147            a larger kernel).
 148          - Run the section mismatch analysis for each module/built-in.o file.
 149            When we run the section mismatch analysis on vmlinux.o, we
 150            lose valueble information about where the mismatch was
 151            introduced.
 152            Running the analysis for each module/built-in.o file
 153            tells where the mismatch happens much closer to the
 154            source. The drawback is that the same mismatch is
 155            reported at least twice.
 156          - Enable verbose reporting from modpost in order to help resolve
 157            the section mismatches that are reported.
 158
 159config DEBUG_KERNEL
 160        bool "Kernel debugging"
 161        help
 162          Say Y here if you are developing drivers or trying to debug and
 163          identify kernel problems.
 164
 165config DEBUG_SHIRQ
 166        bool "Debug shared IRQ handlers"
 167        depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 168        help
 169          Enable this to generate a spurious interrupt as soon as a shared
 170          interrupt handler is registered, and just before one is deregistered.
 171          Drivers ought to be able to handle interrupts coming in at those
 172          points; some don't and need to be caught.
 173
 174config LOCKUP_DETECTOR
 175        bool "Detect Hard and Soft Lockups"
 176        depends on DEBUG_KERNEL && !S390
 177        help
 178          Say Y here to enable the kernel to act as a watchdog to detect
 179          hard and soft lockups.
 180
 181          Softlockups are bugs that cause the kernel to loop in kernel
 182          mode for more than 20 seconds, without giving other tasks a
 183          chance to run.  The current stack trace is displayed upon
 184          detection and the system will stay locked up.
 185
 186          Hardlockups are bugs that cause the CPU to loop in kernel mode
 187          for more than 10 seconds, without letting other interrupts have a
 188          chance to run.  The current stack trace is displayed upon detection
 189          and the system will stay locked up.
 190
 191          The overhead should be minimal.  A periodic hrtimer runs to
 192          generate interrupts and kick the watchdog task every 4 seconds.
 193          An NMI is generated every 10 seconds or so to check for hardlockups.
 194
 195          The frequency of hrtimer and NMI events and the soft and hard lockup
 196          thresholds can be controlled through the sysctl watchdog_thresh.
 197
 198config HARDLOCKUP_DETECTOR
 199        def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
 200                 !HAVE_NMI_WATCHDOG
 201
 202config BOOTPARAM_HARDLOCKUP_PANIC
 203        bool "Panic (Reboot) On Hard Lockups"
 204        depends on LOCKUP_DETECTOR
 205        help
 206          Say Y here to enable the kernel to panic on "hard lockups",
 207          which are bugs that cause the kernel to loop in kernel
 208          mode with interrupts disabled for more than 10 seconds (configurable
 209          using the watchdog_thresh sysctl).
 210
 211          Say N if unsure.
 212
 213config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
 214        int
 215        depends on LOCKUP_DETECTOR
 216        range 0 1
 217        default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
 218        default 1 if BOOTPARAM_HARDLOCKUP_PANIC
 219
 220config BOOTPARAM_SOFTLOCKUP_PANIC
 221        bool "Panic (Reboot) On Soft Lockups"
 222        depends on LOCKUP_DETECTOR
 223        help
 224          Say Y here to enable the kernel to panic on "soft lockups",
 225          which are bugs that cause the kernel to loop in kernel
 226          mode for more than 20 seconds (configurable using the watchdog_thresh
 227          sysctl), without giving other tasks a chance to run.
 228
 229          The panic can be used in combination with panic_timeout,
 230          to cause the system to reboot automatically after a
 231          lockup has been detected. This feature is useful for
 232          high-availability systems that have uptime guarantees and
 233          where a lockup must be resolved ASAP.
 234
 235          Say N if unsure.
 236
 237config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 238        int
 239        depends on LOCKUP_DETECTOR
 240        range 0 1
 241        default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 242        default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 243
 244config PANIC_ON_OOPS
 245        bool "Panic on Oops" if EXPERT
 246        default n
 247        help
 248          Say Y here to enable the kernel to panic when it oopses. This
 249          has the same effect as setting oops=panic on the kernel command
 250          line.
 251
 252          This feature is useful to ensure that the kernel does not do
 253          anything erroneous after an oops which could result in data
 254          corruption or other issues.
 255
 256          Say N if unsure.
 257
 258config PANIC_ON_OOPS_VALUE
 259        int
 260        range 0 1
 261        default 0 if !PANIC_ON_OOPS
 262        default 1 if PANIC_ON_OOPS
 263
 264config DETECT_HUNG_TASK
 265        bool "Detect Hung Tasks"
 266        depends on DEBUG_KERNEL
 267        default LOCKUP_DETECTOR
 268        help
 269          Say Y here to enable the kernel to detect "hung tasks",
 270          which are bugs that cause the task to be stuck in
 271          uninterruptible "D" state indefinitiley.
 272
 273          When a hung task is detected, the kernel will print the
 274          current stack trace (which you should report), but the
 275          task will stay in uninterruptible state. If lockdep is
 276          enabled then all held locks will also be reported. This
 277          feature has negligible overhead.
 278
 279config DEFAULT_HUNG_TASK_TIMEOUT
 280        int "Default timeout for hung task detection (in seconds)"
 281        depends on DETECT_HUNG_TASK
 282        default 120
 283        help
 284          This option controls the default timeout (in seconds) used
 285          to determine when a task has become non-responsive and should
 286          be considered hung.
 287
 288          It can be adjusted at runtime via the kernel.hung_task_timeout_secs
 289          sysctl or by writing a value to
 290          /proc/sys/kernel/hung_task_timeout_secs.
 291
 292          A timeout of 0 disables the check.  The default is two minutes.
 293          Keeping the default should be fine in most cases.
 294
 295config BOOTPARAM_HUNG_TASK_PANIC
 296        bool "Panic (Reboot) On Hung Tasks"
 297        depends on DETECT_HUNG_TASK
 298        help
 299          Say Y here to enable the kernel to panic on "hung tasks",
 300          which are bugs that cause the kernel to leave a task stuck
 301          in uninterruptible "D" state.
 302
 303          The panic can be used in combination with panic_timeout,
 304          to cause the system to reboot automatically after a
 305          hung task has been detected. This feature is useful for
 306          high-availability systems that have uptime guarantees and
 307          where a hung tasks must be resolved ASAP.
 308
 309          Say N if unsure.
 310
 311config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 312        int
 313        depends on DETECT_HUNG_TASK
 314        range 0 1
 315        default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 316        default 1 if BOOTPARAM_HUNG_TASK_PANIC
 317
 318config SCHED_DEBUG
 319        bool "Collect scheduler debugging info"
 320        depends on DEBUG_KERNEL && PROC_FS
 321        default y
 322        help
 323          If you say Y here, the /proc/sched_debug file will be provided
 324          that can help debug the scheduler. The runtime overhead of this
 325          option is minimal.
 326
 327config SCHEDSTATS
 328        bool "Collect scheduler statistics"
 329        depends on DEBUG_KERNEL && PROC_FS
 330        help
 331          If you say Y here, additional code will be inserted into the
 332          scheduler and related routines to collect statistics about
 333          scheduler behavior and provide them in /proc/schedstat.  These
 334          stats may be useful for both tuning and debugging the scheduler
 335          If you aren't debugging the scheduler or trying to tune a specific
 336          application, you can say N to avoid the very slight overhead
 337          this adds.
 338
 339config TIMER_STATS
 340        bool "Collect kernel timers statistics"
 341        depends on DEBUG_KERNEL && PROC_FS
 342        help
 343          If you say Y here, additional code will be inserted into the
 344          timer routines to collect statistics about kernel timers being
 345          reprogrammed. The statistics can be read from /proc/timer_stats.
 346          The statistics collection is started by writing 1 to /proc/timer_stats,
 347          writing 0 stops it. This feature is useful to collect information
 348          about timer usage patterns in kernel and userspace. This feature
 349          is lightweight if enabled in the kernel config but not activated
 350          (it defaults to deactivated on bootup and will only be activated
 351          if some application like powertop activates it explicitly).
 352
 353config DEBUG_OBJECTS
 354        bool "Debug object operations"
 355        depends on DEBUG_KERNEL
 356        help
 357          If you say Y here, additional code will be inserted into the
 358          kernel to track the life time of various objects and validate
 359          the operations on those objects.
 360
 361config DEBUG_OBJECTS_SELFTEST
 362        bool "Debug objects selftest"
 363        depends on DEBUG_OBJECTS
 364        help
 365          This enables the selftest of the object debug code.
 366
 367config DEBUG_OBJECTS_FREE
 368        bool "Debug objects in freed memory"
 369        depends on DEBUG_OBJECTS
 370        help
 371          This enables checks whether a k/v free operation frees an area
 372          which contains an object which has not been deactivated
 373          properly. This can make kmalloc/kfree-intensive workloads
 374          much slower.
 375
 376config DEBUG_OBJECTS_TIMERS
 377        bool "Debug timer objects"
 378        depends on DEBUG_OBJECTS
 379        help
 380          If you say Y here, additional code will be inserted into the
 381          timer routines to track the life time of timer objects and
 382          validate the timer operations.
 383
 384config DEBUG_OBJECTS_WORK
 385        bool "Debug work objects"
 386        depends on DEBUG_OBJECTS
 387        help
 388          If you say Y here, additional code will be inserted into the
 389          work queue routines to track the life time of work objects and
 390          validate the work operations.
 391
 392config DEBUG_OBJECTS_RCU_HEAD
 393        bool "Debug RCU callbacks objects"
 394        depends on DEBUG_OBJECTS
 395        help
 396          Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 397
 398config DEBUG_OBJECTS_PERCPU_COUNTER
 399        bool "Debug percpu counter objects"
 400        depends on DEBUG_OBJECTS
 401        help
 402          If you say Y here, additional code will be inserted into the
 403          percpu counter routines to track the life time of percpu counter
 404          objects and validate the percpu counter operations.
 405
 406config DEBUG_OBJECTS_ENABLE_DEFAULT
 407        int "debug_objects bootup default value (0-1)"
 408        range 0 1
 409        default "1"
 410        depends on DEBUG_OBJECTS
 411        help
 412          Debug objects boot parameter default value
 413
 414config DEBUG_SLAB
 415        bool "Debug slab memory allocations"
 416        depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 417        help
 418          Say Y here to have the kernel do limited verification on memory
 419          allocation as well as poisoning memory on free to catch use of freed
 420          memory. This can make kmalloc/kfree-intensive workloads much slower.
 421
 422config DEBUG_SLAB_LEAK
 423        bool "Memory leak debugging"
 424        depends on DEBUG_SLAB
 425
 426config SLUB_DEBUG_ON
 427        bool "SLUB debugging on by default"
 428        depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 429        default n
 430        help
 431          Boot with debugging on by default. SLUB boots by default with
 432          the runtime debug capabilities switched off. Enabling this is
 433          equivalent to specifying the "slub_debug" parameter on boot.
 434          There is no support for more fine grained debug control like
 435          possible with slub_debug=xxx. SLUB debugging may be switched
 436          off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 437          "slub_debug=-".
 438
 439config SLUB_STATS
 440        default n
 441        bool "Enable SLUB performance statistics"
 442        depends on SLUB && SYSFS
 443        help
 444          SLUB statistics are useful to debug SLUBs allocation behavior in
 445          order find ways to optimize the allocator. This should never be
 446          enabled for production use since keeping statistics slows down
 447          the allocator by a few percentage points. The slabinfo command
 448          supports the determination of the most active slabs to figure
 449          out which slabs are relevant to a particular load.
 450          Try running: slabinfo -DA
 451
 452config DEBUG_KMEMLEAK
 453        bool "Kernel memory leak detector"
 454        depends on DEBUG_KERNEL && EXPERIMENTAL && \
 455                (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
 456
 457        select DEBUG_FS
 458        select STACKTRACE if STACKTRACE_SUPPORT
 459        select KALLSYMS
 460        select CRC32
 461        help
 462          Say Y here if you want to enable the memory leak
 463          detector. The memory allocation/freeing is traced in a way
 464          similar to the Boehm's conservative garbage collector, the
 465          difference being that the orphan objects are not freed but
 466          only shown in /sys/kernel/debug/kmemleak. Enabling this
 467          feature will introduce an overhead to memory
 468          allocations. See Documentation/kmemleak.txt for more
 469          details.
 470
 471          Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 472          of finding leaks due to the slab objects poisoning.
 473
 474          In order to access the kmemleak file, debugfs needs to be
 475          mounted (usually at /sys/kernel/debug).
 476
 477config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 478        int "Maximum kmemleak early log entries"
 479        depends on DEBUG_KMEMLEAK
 480        range 200 40000
 481        default 400
 482        help
 483          Kmemleak must track all the memory allocations to avoid
 484          reporting false positives. Since memory may be allocated or
 485          freed before kmemleak is initialised, an early log buffer is
 486          used to store these actions. If kmemleak reports "early log
 487          buffer exceeded", please increase this value.
 488
 489config DEBUG_KMEMLEAK_TEST
 490        tristate "Simple test for the kernel memory leak detector"
 491        depends on DEBUG_KMEMLEAK && m
 492        help
 493          This option enables a module that explicitly leaks memory.
 494
 495          If unsure, say N.
 496
 497config DEBUG_KMEMLEAK_DEFAULT_OFF
 498        bool "Default kmemleak to off"
 499        depends on DEBUG_KMEMLEAK
 500        help
 501          Say Y here to disable kmemleak by default. It can then be enabled
 502          on the command line via kmemleak=on.
 503
 504config DEBUG_PREEMPT
 505        bool "Debug preemptible kernel"
 506        depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 507        default y
 508        help
 509          If you say Y here then the kernel will use a debug variant of the
 510          commonly used smp_processor_id() function and will print warnings
 511          if kernel code uses it in a preemption-unsafe way. Also, the kernel
 512          will detect preemption count underflows.
 513
 514config DEBUG_RT_MUTEXES
 515        bool "RT Mutex debugging, deadlock detection"
 516        depends on DEBUG_KERNEL && RT_MUTEXES
 517        help
 518         This allows rt mutex semantics violations and rt mutex related
 519         deadlocks (lockups) to be detected and reported automatically.
 520
 521config DEBUG_PI_LIST
 522        bool
 523        default y
 524        depends on DEBUG_RT_MUTEXES
 525
 526config RT_MUTEX_TESTER
 527        bool "Built-in scriptable tester for rt-mutexes"
 528        depends on DEBUG_KERNEL && RT_MUTEXES
 529        help
 530          This option enables a rt-mutex tester.
 531
 532config DEBUG_SPINLOCK
 533        bool "Spinlock and rw-lock debugging: basic checks"
 534        depends on DEBUG_KERNEL
 535        select UNINLINE_SPIN_UNLOCK
 536        help
 537          Say Y here and build SMP to catch missing spinlock initialization
 538          and certain other kinds of spinlock errors commonly made.  This is
 539          best used in conjunction with the NMI watchdog so that spinlock
 540          deadlocks are also debuggable.
 541
 542config DEBUG_MUTEXES
 543        bool "Mutex debugging: basic checks"
 544        depends on DEBUG_KERNEL
 545        help
 546         This feature allows mutex semantics violations to be detected and
 547         reported.
 548
 549config DEBUG_LOCK_ALLOC
 550        bool "Lock debugging: detect incorrect freeing of live locks"
 551        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 552        select DEBUG_SPINLOCK
 553        select DEBUG_MUTEXES
 554        select LOCKDEP
 555        help
 556         This feature will check whether any held lock (spinlock, rwlock,
 557         mutex or rwsem) is incorrectly freed by the kernel, via any of the
 558         memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 559         vfree(), etc.), whether a live lock is incorrectly reinitialized via
 560         spin_lock_init()/mutex_init()/etc., or whether there is any lock
 561         held during task exit.
 562
 563config PROVE_LOCKING
 564        bool "Lock debugging: prove locking correctness"
 565        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 566        select LOCKDEP
 567        select DEBUG_SPINLOCK
 568        select DEBUG_MUTEXES
 569        select DEBUG_LOCK_ALLOC
 570        select TRACE_IRQFLAGS
 571        default n
 572        help
 573         This feature enables the kernel to prove that all locking
 574         that occurs in the kernel runtime is mathematically
 575         correct: that under no circumstance could an arbitrary (and
 576         not yet triggered) combination of observed locking
 577         sequences (on an arbitrary number of CPUs, running an
 578         arbitrary number of tasks and interrupt contexts) cause a
 579         deadlock.
 580
 581         In short, this feature enables the kernel to report locking
 582         related deadlocks before they actually occur.
 583
 584         The proof does not depend on how hard and complex a
 585         deadlock scenario would be to trigger: how many
 586         participant CPUs, tasks and irq-contexts would be needed
 587         for it to trigger. The proof also does not depend on
 588         timing: if a race and a resulting deadlock is possible
 589         theoretically (no matter how unlikely the race scenario
 590         is), it will be proven so and will immediately be
 591         reported by the kernel (once the event is observed that
 592         makes the deadlock theoretically possible).
 593
 594         If a deadlock is impossible (i.e. the locking rules, as
 595         observed by the kernel, are mathematically correct), the
 596         kernel reports nothing.
 597
 598         NOTE: this feature can also be enabled for rwlocks, mutexes
 599         and rwsems - in which case all dependencies between these
 600         different locking variants are observed and mapped too, and
 601         the proof of observed correctness is also maintained for an
 602         arbitrary combination of these separate locking variants.
 603
 604         For more details, see Documentation/lockdep-design.txt.
 605
 606config PROVE_RCU
 607        bool "RCU debugging: prove RCU correctness"
 608        depends on PROVE_LOCKING
 609        default n
 610        help
 611         This feature enables lockdep extensions that check for correct
 612         use of RCU APIs.  This is currently under development.  Say Y
 613         if you want to debug RCU usage or help work on the PROVE_RCU
 614         feature.
 615
 616         Say N if you are unsure.
 617
 618config PROVE_RCU_REPEATEDLY
 619        bool "RCU debugging: don't disable PROVE_RCU on first splat"
 620        depends on PROVE_RCU
 621        default n
 622        help
 623         By itself, PROVE_RCU will disable checking upon issuing the
 624         first warning (or "splat").  This feature prevents such
 625         disabling, allowing multiple RCU-lockdep warnings to be printed
 626         on a single reboot.
 627
 628         Say Y to allow multiple RCU-lockdep warnings per boot.
 629
 630         Say N if you are unsure.
 631
 632config SPARSE_RCU_POINTER
 633        bool "RCU debugging: sparse-based checks for pointer usage"
 634        default n
 635        help
 636         This feature enables the __rcu sparse annotation for
 637         RCU-protected pointers.  This annotation will cause sparse
 638         to flag any non-RCU used of annotated pointers.  This can be
 639         helpful when debugging RCU usage.  Please note that this feature
 640         is not intended to enforce code cleanliness; it is instead merely
 641         a debugging aid.
 642
 643         Say Y to make sparse flag questionable use of RCU-protected pointers
 644
 645         Say N if you are unsure.
 646
 647config LOCKDEP
 648        bool
 649        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 650        select STACKTRACE
 651        select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 652        select KALLSYMS
 653        select KALLSYMS_ALL
 654
 655config LOCK_STAT
 656        bool "Lock usage statistics"
 657        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 658        select LOCKDEP
 659        select DEBUG_SPINLOCK
 660        select DEBUG_MUTEXES
 661        select DEBUG_LOCK_ALLOC
 662        default n
 663        help
 664         This feature enables tracking lock contention points
 665
 666         For more details, see Documentation/lockstat.txt
 667
 668         This also enables lock events required by "perf lock",
 669         subcommand of perf.
 670         If you want to use "perf lock", you also need to turn on
 671         CONFIG_EVENT_TRACING.
 672
 673         CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 674         (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 675
 676config DEBUG_LOCKDEP
 677        bool "Lock dependency engine debugging"
 678        depends on DEBUG_KERNEL && LOCKDEP
 679        help
 680          If you say Y here, the lock dependency engine will do
 681          additional runtime checks to debug itself, at the price
 682          of more runtime overhead.
 683
 684config TRACE_IRQFLAGS
 685        bool
 686        help
 687          Enables hooks to interrupt enabling and disabling for
 688          either tracing or lock debugging.
 689
 690config DEBUG_ATOMIC_SLEEP
 691        bool "Sleep inside atomic section checking"
 692        select PREEMPT_COUNT
 693        depends on DEBUG_KERNEL
 694        help
 695          If you say Y here, various routines which may sleep will become very
 696          noisy if they are called inside atomic sections: when a spinlock is
 697          held, inside an rcu read side critical section, inside preempt disabled
 698          sections, inside an interrupt, etc...
 699
 700config DEBUG_LOCKING_API_SELFTESTS
 701        bool "Locking API boot-time self-tests"
 702        depends on DEBUG_KERNEL
 703        help
 704          Say Y here if you want the kernel to run a short self-test during
 705          bootup. The self-test checks whether common types of locking bugs
 706          are detected by debugging mechanisms or not. (if you disable
 707          lock debugging then those bugs wont be detected of course.)
 708          The following locking APIs are covered: spinlocks, rwlocks,
 709          mutexes and rwsems.
 710
 711config STACKTRACE
 712        bool
 713        depends on STACKTRACE_SUPPORT
 714
 715config DEBUG_STACK_USAGE
 716        bool "Stack utilization instrumentation"
 717        depends on DEBUG_KERNEL && !IA64 && !PARISC
 718        help
 719          Enables the display of the minimum amount of free stack which each
 720          task has ever had available in the sysrq-T and sysrq-P debug output.
 721
 722          This option will slow down process creation somewhat.
 723
 724config DEBUG_KOBJECT
 725        bool "kobject debugging"
 726        depends on DEBUG_KERNEL
 727        help
 728          If you say Y here, some extra kobject debugging messages will be sent
 729          to the syslog. 
 730
 731config DEBUG_HIGHMEM
 732        bool "Highmem debugging"
 733        depends on DEBUG_KERNEL && HIGHMEM
 734        help
 735          This options enables addition error checking for high memory systems.
 736          Disable for production systems.
 737
 738config DEBUG_BUGVERBOSE
 739        bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
 740        depends on BUG
 741        depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 742                   FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || TILE
 743        default y
 744        help
 745          Say Y here to make BUG() panics output the file name and line number
 746          of the BUG call as well as the EIP and oops trace.  This aids
 747          debugging but costs about 70-100K of memory.
 748
 749config DEBUG_INFO
 750        bool "Compile the kernel with debug info"
 751        depends on DEBUG_KERNEL
 752        help
 753          If you say Y here the resulting kernel image will include
 754          debugging info resulting in a larger kernel image.
 755          This adds debug symbols to the kernel and modules (gcc -g), and
 756          is needed if you intend to use kernel crashdump or binary object
 757          tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 758          Say Y here only if you plan to debug the kernel.
 759
 760          If unsure, say N.
 761
 762config DEBUG_INFO_REDUCED
 763        bool "Reduce debugging information"
 764        depends on DEBUG_INFO
 765        help
 766          If you say Y here gcc is instructed to generate less debugging
 767          information for structure types. This means that tools that
 768          need full debugging information (like kgdb or systemtap) won't
 769          be happy. But if you merely need debugging information to
 770          resolve line numbers there is no loss. Advantage is that
 771          build directory object sizes shrink dramatically over a full
 772          DEBUG_INFO build and compile times are reduced too.
 773          Only works with newer gcc versions.
 774
 775config DEBUG_VM
 776        bool "Debug VM"
 777        depends on DEBUG_KERNEL
 778        help
 779          Enable this to turn on extended checks in the virtual-memory system
 780          that may impact performance.
 781
 782          If unsure, say N.
 783
 784config DEBUG_VIRTUAL
 785        bool "Debug VM translations"
 786        depends on DEBUG_KERNEL && X86
 787        help
 788          Enable some costly sanity checks in virtual to page code. This can
 789          catch mistakes with virt_to_page() and friends.
 790
 791          If unsure, say N.
 792
 793config DEBUG_NOMMU_REGIONS
 794        bool "Debug the global anon/private NOMMU mapping region tree"
 795        depends on DEBUG_KERNEL && !MMU
 796        help
 797          This option causes the global tree of anonymous and private mapping
 798          regions to be regularly checked for invalid topology.
 799
 800config DEBUG_WRITECOUNT
 801        bool "Debug filesystem writers count"
 802        depends on DEBUG_KERNEL
 803        help
 804          Enable this to catch wrong use of the writers count in struct
 805          vfsmount.  This will increase the size of each file struct by
 806          32 bits.
 807
 808          If unsure, say N.
 809
 810config DEBUG_MEMORY_INIT
 811        bool "Debug memory initialisation" if EXPERT
 812        default !EXPERT
 813        help
 814          Enable this for additional checks during memory initialisation.
 815          The sanity checks verify aspects of the VM such as the memory model
 816          and other information provided by the architecture. Verbose
 817          information will be printed at KERN_DEBUG loglevel depending
 818          on the mminit_loglevel= command-line option.
 819
 820          If unsure, say Y
 821
 822config DEBUG_LIST
 823        bool "Debug linked list manipulation"
 824        depends on DEBUG_KERNEL
 825        help
 826          Enable this to turn on extended checks in the linked-list
 827          walking routines.
 828
 829          If unsure, say N.
 830
 831config TEST_LIST_SORT
 832        bool "Linked list sorting test"
 833        depends on DEBUG_KERNEL
 834        help
 835          Enable this to turn on 'list_sort()' function test. This test is
 836          executed only once during system boot, so affects only boot time.
 837
 838          If unsure, say N.
 839
 840config DEBUG_SG
 841        bool "Debug SG table operations"
 842        depends on DEBUG_KERNEL
 843        help
 844          Enable this to turn on checks on scatter-gather tables. This can
 845          help find problems with drivers that do not properly initialize
 846          their sg tables.
 847
 848          If unsure, say N.
 849
 850config DEBUG_NOTIFIERS
 851        bool "Debug notifier call chains"
 852        depends on DEBUG_KERNEL
 853        help
 854          Enable this to turn on sanity checking for notifier call chains.
 855          This is most useful for kernel developers to make sure that
 856          modules properly unregister themselves from notifier chains.
 857          This is a relatively cheap check but if you care about maximum
 858          performance, say N.
 859
 860config DEBUG_CREDENTIALS
 861        bool "Debug credential management"
 862        depends on DEBUG_KERNEL
 863        help
 864          Enable this to turn on some debug checking for credential
 865          management.  The additional code keeps track of the number of
 866          pointers from task_structs to any given cred struct, and checks to
 867          see that this number never exceeds the usage count of the cred
 868          struct.
 869
 870          Furthermore, if SELinux is enabled, this also checks that the
 871          security pointer in the cred struct is never seen to be invalid.
 872
 873          If unsure, say N.
 874
 875#
 876# Select this config option from the architecture Kconfig, if it
 877# is preferred to always offer frame pointers as a config
 878# option on the architecture (regardless of KERNEL_DEBUG):
 879#
 880config ARCH_WANT_FRAME_POINTERS
 881        bool
 882        help
 883
 884config FRAME_POINTER
 885        bool "Compile the kernel with frame pointers"
 886        depends on DEBUG_KERNEL && \
 887                (CRIS || M68K || FRV || UML || \
 888                 AVR32 || SUPERH || BLACKFIN || MN10300) || \
 889                ARCH_WANT_FRAME_POINTERS
 890        default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 891        help
 892          If you say Y here the resulting kernel image will be slightly
 893          larger and slower, but it gives very useful debugging information
 894          in case of kernel bugs. (precise oopses/stacktraces/warnings)
 895
 896config BOOT_PRINTK_DELAY
 897        bool "Delay each boot printk message by N milliseconds"
 898        depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 899        help
 900          This build option allows you to read kernel boot messages
 901          by inserting a short delay after each one.  The delay is
 902          specified in milliseconds on the kernel command line,
 903          using "boot_delay=N".
 904
 905          It is likely that you would also need to use "lpj=M" to preset
 906          the "loops per jiffie" value.
 907          See a previous boot log for the "lpj" value to use for your
 908          system, and then set "lpj=M" before setting "boot_delay=N".
 909          NOTE:  Using this option may adversely affect SMP systems.
 910          I.e., processors other than the first one may not boot up.
 911          BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
 912          what it believes to be lockup conditions.
 913
 914config RCU_TORTURE_TEST
 915        tristate "torture tests for RCU"
 916        depends on DEBUG_KERNEL
 917        default n
 918        help
 919          This option provides a kernel module that runs torture tests
 920          on the RCU infrastructure.  The kernel module may be built
 921          after the fact on the running kernel to be tested, if desired.
 922
 923          Say Y here if you want RCU torture tests to be built into
 924          the kernel.
 925          Say M if you want the RCU torture tests to build as a module.
 926          Say N if you are unsure.
 927
 928config RCU_TORTURE_TEST_RUNNABLE
 929        bool "torture tests for RCU runnable by default"
 930        depends on RCU_TORTURE_TEST = y
 931        default n
 932        help
 933          This option provides a way to build the RCU torture tests
 934          directly into the kernel without them starting up at boot
 935          time.  You can use /proc/sys/kernel/rcutorture_runnable
 936          to manually override this setting.  This /proc file is
 937          available only when the RCU torture tests have been built
 938          into the kernel.
 939
 940          Say Y here if you want the RCU torture tests to start during
 941          boot (you probably don't).
 942          Say N here if you want the RCU torture tests to start only
 943          after being manually enabled via /proc.
 944
 945config RCU_CPU_STALL_TIMEOUT
 946        int "RCU CPU stall timeout in seconds"
 947        depends on TREE_RCU || TREE_PREEMPT_RCU
 948        range 3 300
 949        default 60
 950        help
 951          If a given RCU grace period extends more than the specified
 952          number of seconds, a CPU stall warning is printed.  If the
 953          RCU grace period persists, additional CPU stall warnings are
 954          printed at more widely spaced intervals.
 955
 956config RCU_CPU_STALL_VERBOSE
 957        bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 958        depends on TREE_PREEMPT_RCU
 959        default y
 960        help
 961          This option causes RCU to printk detailed per-task information
 962          for any tasks that are stalling the current RCU grace period.
 963
 964          Say N if you are unsure.
 965
 966          Say Y if you want to enable such checks.
 967
 968config RCU_CPU_STALL_INFO
 969        bool "Print additional diagnostics on RCU CPU stall"
 970        depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
 971        default n
 972        help
 973          For each stalled CPU that is aware of the current RCU grace
 974          period, print out additional per-CPU diagnostic information
 975          regarding scheduling-clock ticks, idle state, and,
 976          for RCU_FAST_NO_HZ kernels, idle-entry state.
 977
 978          Say N if you are unsure.
 979
 980          Say Y if you want to enable such diagnostics.
 981
 982config RCU_TRACE
 983        bool "Enable tracing for RCU"
 984        depends on DEBUG_KERNEL
 985        help
 986          This option provides tracing in RCU which presents stats
 987          in debugfs for debugging RCU implementation.
 988
 989          Say Y here if you want to enable RCU tracing
 990          Say N if you are unsure.
 991
 992config KPROBES_SANITY_TEST
 993        bool "Kprobes sanity tests"
 994        depends on DEBUG_KERNEL
 995        depends on KPROBES
 996        default n
 997        help
 998          This option provides for testing basic kprobes functionality on
 999          boot. A sample kprobe, jprobe and kretprobe are inserted and
1000          verified for functionality.
1001
1002          Say N if you are unsure.
1003
1004config BACKTRACE_SELF_TEST
1005        tristate "Self test for the backtrace code"
1006        depends on DEBUG_KERNEL
1007        default n
1008        help
1009          This option provides a kernel module that can be used to test
1010          the kernel stack backtrace code. This option is not useful
1011          for distributions or general kernels, but only for kernel
1012          developers working on architecture code.
1013
1014          Note that if you want to also test saved backtraces, you will
1015          have to enable STACKTRACE as well.
1016
1017          Say N if you are unsure.
1018
1019config DEBUG_BLOCK_EXT_DEVT
1020        bool "Force extended block device numbers and spread them"
1021        depends on DEBUG_KERNEL
1022        depends on BLOCK
1023        default n
1024        help
1025          BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1026          SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1027          YOU ARE DOING.  Distros, please enable this and fix whatever
1028          is broken.
1029
1030          Conventionally, block device numbers are allocated from
1031          predetermined contiguous area.  However, extended block area
1032          may introduce non-contiguous block device numbers.  This
1033          option forces most block device numbers to be allocated from
1034          the extended space and spreads them to discover kernel or
1035          userland code paths which assume predetermined contiguous
1036          device number allocation.
1037
1038          Note that turning on this debug option shuffles all the
1039          device numbers for all IDE and SCSI devices including libata
1040          ones, so root partition specified using device number
1041          directly (via rdev or root=MAJ:MIN) won't work anymore.
1042          Textual device names (root=/dev/sdXn) will continue to work.
1043
1044          Say N if you are unsure.
1045
1046config DEBUG_FORCE_WEAK_PER_CPU
1047        bool "Force weak per-cpu definitions"
1048        depends on DEBUG_KERNEL
1049        help
1050          s390 and alpha require percpu variables in modules to be
1051          defined weak to work around addressing range issue which
1052          puts the following two restrictions on percpu variable
1053          definitions.
1054
1055          1. percpu symbols must be unique whether static or not
1056          2. percpu variables can't be defined inside a function
1057
1058          To ensure that generic code follows the above rules, this
1059          option forces all percpu variables to be defined as weak.
1060
1061config DEBUG_PER_CPU_MAPS
1062        bool "Debug access to per_cpu maps"
1063        depends on DEBUG_KERNEL
1064        depends on SMP
1065        help
1066          Say Y to verify that the per_cpu map being accessed has
1067          been set up. This adds a fair amount of code to kernel memory
1068          and decreases performance.
1069
1070          Say N if unsure.
1071
1072config LKDTM
1073        tristate "Linux Kernel Dump Test Tool Module"
1074        depends on DEBUG_FS
1075        depends on BLOCK
1076        default n
1077        help
1078        This module enables testing of the different dumping mechanisms by
1079        inducing system failures at predefined crash points.
1080        If you don't need it: say N
1081        Choose M here to compile this code as a module. The module will be
1082        called lkdtm.
1083
1084        Documentation on how to use the module can be found in
1085        Documentation/fault-injection/provoke-crashes.txt
1086
1087config NOTIFIER_ERROR_INJECTION
1088        tristate "Notifier error injection"
1089        depends on DEBUG_KERNEL
1090        select DEBUG_FS
1091        help
1092          This option provides the ability to inject artifical errors to
1093          specified notifier chain callbacks. It is useful to test the error
1094          handling of notifier call chain failures.
1095
1096          Say N if unsure.
1097
1098config CPU_NOTIFIER_ERROR_INJECT
1099        tristate "CPU notifier error injection module"
1100        depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1101        help
1102          This option provides a kernel module that can be used to test
1103          the error handling of the cpu notifiers by injecting artifical
1104          errors to CPU notifier chain callbacks.  It is controlled through
1105          debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1106
1107          If the notifier call chain should be failed with some events
1108          notified, write the error code to "actions/<notifier event>/error".
1109
1110          Example: Inject CPU offline error (-1 == -EPERM)
1111
1112          # cd /sys/kernel/debug/notifier-error-inject/cpu
1113          # echo -1 > actions/CPU_DOWN_PREPARE/error
1114          # echo 0 > /sys/devices/system/cpu/cpu1/online
1115          bash: echo: write error: Operation not permitted
1116
1117          To compile this code as a module, choose M here: the module will
1118          be called cpu-notifier-error-inject.
1119
1120          If unsure, say N.
1121
1122config PM_NOTIFIER_ERROR_INJECT
1123        tristate "PM notifier error injection module"
1124        depends on PM && NOTIFIER_ERROR_INJECTION
1125        default m if PM_DEBUG
1126        help
1127          This option provides the ability to inject artifical errors to
1128          PM notifier chain callbacks.  It is controlled through debugfs
1129          interface /sys/kernel/debug/notifier-error-inject/pm
1130
1131          If the notifier call chain should be failed with some events
1132          notified, write the error code to "actions/<notifier event>/error".
1133
1134          Example: Inject PM suspend error (-12 = -ENOMEM)
1135
1136          # cd /sys/kernel/debug/notifier-error-inject/pm/
1137          # echo -12 > actions/PM_SUSPEND_PREPARE/error
1138          # echo mem > /sys/power/state
1139          bash: echo: write error: Cannot allocate memory
1140
1141          To compile this code as a module, choose M here: the module will
1142          be called pm-notifier-error-inject.
1143
1144          If unsure, say N.
1145
1146config MEMORY_NOTIFIER_ERROR_INJECT
1147        tristate "Memory hotplug notifier error injection module"
1148        depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1149        help
1150          This option provides the ability to inject artifical errors to
1151          memory hotplug notifier chain callbacks.  It is controlled through
1152          debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
1153
1154          If the notifier call chain should be failed with some events
1155          notified, write the error code to "actions/<notifier event>/error".
1156
1157          Example: Inject memory hotplug offline error (-12 == -ENOMEM)
1158
1159          # cd /sys/kernel/debug/notifier-error-inject/memory
1160          # echo -12 > actions/MEM_GOING_OFFLINE/error
1161          # echo offline > /sys/devices/system/memory/memoryXXX/state
1162          bash: echo: write error: Cannot allocate memory
1163
1164          To compile this code as a module, choose M here: the module will
1165          be called pSeries-reconfig-notifier-error-inject.
1166
1167          If unsure, say N.
1168
1169config PSERIES_RECONFIG_NOTIFIER_ERROR_INJECT
1170        tristate "pSeries reconfig notifier error injection module"
1171        depends on PPC_PSERIES && NOTIFIER_ERROR_INJECTION
1172        help
1173          This option provides the ability to inject artifical errors to
1174          pSeries reconfig notifier chain callbacks.  It is controlled
1175          through debugfs interface under
1176          /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/
1177
1178          If the notifier call chain should be failed with some events
1179          notified, write the error code to "actions/<notifier event>/error".
1180
1181          To compile this code as a module, choose M here: the module will
1182          be called memory-notifier-error-inject.
1183
1184          If unsure, say N.
1185
1186config FAULT_INJECTION
1187        bool "Fault-injection framework"
1188        depends on DEBUG_KERNEL
1189        help
1190          Provide fault-injection framework.
1191          For more details, see Documentation/fault-injection/.
1192
1193config FAILSLAB
1194        bool "Fault-injection capability for kmalloc"
1195        depends on FAULT_INJECTION
1196        depends on SLAB || SLUB
1197        help
1198          Provide fault-injection capability for kmalloc.
1199
1200config FAIL_PAGE_ALLOC
1201        bool "Fault-injection capabilitiy for alloc_pages()"
1202        depends on FAULT_INJECTION
1203        help
1204          Provide fault-injection capability for alloc_pages().
1205
1206config FAIL_MAKE_REQUEST
1207        bool "Fault-injection capability for disk IO"
1208        depends on FAULT_INJECTION && BLOCK
1209        help
1210          Provide fault-injection capability for disk IO.
1211
1212config FAIL_IO_TIMEOUT
1213        bool "Fault-injection capability for faking disk interrupts"
1214        depends on FAULT_INJECTION && BLOCK
1215        help
1216          Provide fault-injection capability on end IO handling. This
1217          will make the block layer "forget" an interrupt as configured,
1218          thus exercising the error handling.
1219
1220          Only works with drivers that use the generic timeout handling,
1221          for others it wont do anything.
1222
1223config FAIL_MMC_REQUEST
1224        bool "Fault-injection capability for MMC IO"
1225        select DEBUG_FS
1226        depends on FAULT_INJECTION && MMC
1227        help
1228          Provide fault-injection capability for MMC IO.
1229          This will make the mmc core return data errors. This is
1230          useful to test the error handling in the mmc block device
1231          and to test how the mmc host driver handles retries from
1232          the block device.
1233
1234config FAULT_INJECTION_DEBUG_FS
1235        bool "Debugfs entries for fault-injection capabilities"
1236        depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1237        help
1238          Enable configuration of fault-injection capabilities via debugfs.
1239
1240config FAULT_INJECTION_STACKTRACE_FILTER
1241        bool "stacktrace filter for fault-injection capabilities"
1242        depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1243        depends on !X86_64
1244        select STACKTRACE
1245        select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1246        help
1247          Provide stacktrace filter for fault-injection capabilities
1248
1249config LATENCYTOP
1250        bool "Latency measuring infrastructure"
1251        depends on HAVE_LATENCYTOP_SUPPORT
1252        depends on DEBUG_KERNEL
1253        depends on STACKTRACE_SUPPORT
1254        depends on PROC_FS
1255        select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1256        select KALLSYMS
1257        select KALLSYMS_ALL
1258        select STACKTRACE
1259        select SCHEDSTATS
1260        select SCHED_DEBUG
1261        help
1262          Enable this option if you want to use the LatencyTOP tool
1263          to find out which userspace is blocking on what kernel operations.
1264
1265source mm/Kconfig.debug
1266source kernel/trace/Kconfig
1267
1268config PROVIDE_OHCI1394_DMA_INIT
1269        bool "Remote debugging over FireWire early on boot"
1270        depends on PCI && X86
1271        help
1272          If you want to debug problems which hang or crash the kernel early
1273          on boot and the crashing machine has a FireWire port, you can use
1274          this feature to remotely access the memory of the crashed machine
1275          over FireWire. This employs remote DMA as part of the OHCI1394
1276          specification which is now the standard for FireWire controllers.
1277
1278          With remote DMA, you can monitor the printk buffer remotely using
1279          firescope and access all memory below 4GB using fireproxy from gdb.
1280          Even controlling a kernel debugger is possible using remote DMA.
1281
1282          Usage:
1283
1284          If ohci1394_dma=early is used as boot parameter, it will initialize
1285          all OHCI1394 controllers which are found in the PCI config space.
1286
1287          As all changes to the FireWire bus such as enabling and disabling
1288          devices cause a bus reset and thereby disable remote DMA for all
1289          devices, be sure to have the cable plugged and FireWire enabled on
1290          the debugging host before booting the debug target for debugging.
1291
1292          This code (~1k) is freed after boot. By then, the firewire stack
1293          in charge of the OHCI-1394 controllers should be used instead.
1294
1295          See Documentation/debugging-via-ohci1394.txt for more information.
1296
1297config FIREWIRE_OHCI_REMOTE_DMA
1298        bool "Remote debugging over FireWire with firewire-ohci"
1299        depends on FIREWIRE_OHCI
1300        help
1301          This option lets you use the FireWire bus for remote debugging
1302          with help of the firewire-ohci driver. It enables unfiltered
1303          remote DMA in firewire-ohci.
1304          See Documentation/debugging-via-ohci1394.txt for more information.
1305
1306          If unsure, say N.
1307
1308config BUILD_DOCSRC
1309        bool "Build targets in Documentation/ tree"
1310        depends on HEADERS_CHECK
1311        help
1312          This option attempts to build objects from the source files in the
1313          kernel Documentation/ tree.
1314
1315          Say N if you are unsure.
1316
1317config DYNAMIC_DEBUG
1318        bool "Enable dynamic printk() support"
1319        default n
1320        depends on PRINTK
1321        depends on DEBUG_FS
1322        help
1323
1324          Compiles debug level messages into the kernel, which would not
1325          otherwise be available at runtime. These messages can then be
1326          enabled/disabled based on various levels of scope - per source file,
1327          function, module, format string, and line number. This mechanism
1328          implicitly compiles in all pr_debug() and dev_dbg() calls, which
1329          enlarges the kernel text size by about 2%.
1330
1331          If a source file is compiled with DEBUG flag set, any
1332          pr_debug() calls in it are enabled by default, but can be
1333          disabled at runtime as below.  Note that DEBUG flag is
1334          turned on by many CONFIG_*DEBUG* options.
1335
1336          Usage:
1337
1338          Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1339          which is contained in the 'debugfs' filesystem. Thus, the debugfs
1340          filesystem must first be mounted before making use of this feature.
1341          We refer the control file as: <debugfs>/dynamic_debug/control. This
1342          file contains a list of the debug statements that can be enabled. The
1343          format for each line of the file is:
1344
1345                filename:lineno [module]function flags format
1346
1347          filename : source file of the debug statement
1348          lineno : line number of the debug statement
1349          module : module that contains the debug statement
1350          function : function that contains the debug statement
1351          flags : '=p' means the line is turned 'on' for printing
1352          format : the format used for the debug statement
1353
1354          From a live system:
1355
1356                nullarbor:~ # cat <debugfs>/dynamic_debug/control
1357                # filename:lineno [module]function flags format
1358                fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1359                fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1360                fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
1361
1362          Example usage:
1363
1364                // enable the message at line 1603 of file svcsock.c
1365                nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1366                                                <debugfs>/dynamic_debug/control
1367
1368                // enable all the messages in file svcsock.c
1369                nullarbor:~ # echo -n 'file svcsock.c +p' >
1370                                                <debugfs>/dynamic_debug/control
1371
1372                // enable all the messages in the NFS server module
1373                nullarbor:~ # echo -n 'module nfsd +p' >
1374                                                <debugfs>/dynamic_debug/control
1375
1376                // enable all 12 messages in the function svc_process()
1377                nullarbor:~ # echo -n 'func svc_process +p' >
1378                                                <debugfs>/dynamic_debug/control
1379
1380                // disable all 12 messages in the function svc_process()
1381                nullarbor:~ # echo -n 'func svc_process -p' >
1382                                                <debugfs>/dynamic_debug/control
1383
1384          See Documentation/dynamic-debug-howto.txt for additional information.
1385
1386config DMA_API_DEBUG
1387        bool "Enable debugging of DMA-API usage"
1388        depends on HAVE_DMA_API_DEBUG
1389        help
1390          Enable this option to debug the use of the DMA API by device drivers.
1391          With this option you will be able to detect common bugs in device
1392          drivers like double-freeing of DMA mappings or freeing mappings that
1393          were never allocated.
1394          This option causes a performance degredation.  Use only if you want
1395          to debug device drivers. If unsure, say N.
1396
1397config ATOMIC64_SELFTEST
1398        bool "Perform an atomic64_t self-test at boot"
1399        help
1400          Enable this option to test the atomic64_t functions at boot.
1401
1402          If unsure, say N.
1403
1404config ASYNC_RAID6_TEST
1405        tristate "Self test for hardware accelerated raid6 recovery"
1406        depends on ASYNC_RAID6_RECOV
1407        select ASYNC_MEMCPY
1408        ---help---
1409          This is a one-shot self test that permutes through the
1410          recovery of all the possible two disk failure scenarios for a
1411          N-disk array.  Recovery is performed with the asynchronous
1412          raid6 recovery routines, and will optionally use an offload
1413          engine if one is available.
1414
1415          If unsure, say N.
1416
1417source "samples/Kconfig"
1418
1419source "lib/Kconfig.kgdb"
1420
1421source "lib/Kconfig.kmemcheck"
1422
1423config TEST_KSTRTOX
1424        tristate "Test kstrto*() family of functions at runtime"
1425
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