lib/Kconfig.debug

   1
   2 config PRINTK_TIME
   3         bool "Show timing information on printks"
   4         depends on PRINTK
   5         help
   6           Selecting this option causes time stamps of the printk()
   7           messages to be added to the output of the syslog() system
   8           call and at the console.
   9
  10           The timestamp is always recorded internally, and exported
  11           to /dev/kmsg. This flag just specifies if the timestamp should
  12           be included, not that the timestamp is recorded.
  13
  14           The behavior is also controlled by the kernel command line
  15           parameter printk.time=1. See Documentation/kernel-parameters.txt
  16
  17 config DEFAULT_MESSAGE_LOGLEVEL
  18         int "Default message log level (1-7)"
  19         range 1 7
  20         default "4"
  21         help
  22           Default log level for printk statements with no specified priority.
  23
  24           This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
  25           that are auditing their logs closely may want to set it to a lower
  26           priority.
  27
  28 config ENABLE_WARN_DEPRECATED
  29         bool "Enable __deprecated logic"
  30         default y
  31         help
  32           Enable the __deprecated logic in the kernel build.
  33           Disable this to suppress the "warning: 'foo' is deprecated
  34           (declared at kernel/power/somefile.c:1234)" messages.
  35
  36 config ENABLE_MUST_CHECK
  37         bool "Enable __must_check logic"
  38         default y
  39         help
  40           Enable the __must_check logic in the kernel build.  Disable this to
  41           suppress the "warning: ignoring return value of 'foo', declared with
  42           attribute warn_unused_result" messages.
  43
  44 config FRAME_WARN
  45         int "Warn for stack frames larger than (needs gcc 4.4)"
  46         range 0 8192
  47         default 1024 if !64BIT
  48         default 2048 if 64BIT
  49         help
  50           Tell gcc to warn at build time for stack frames larger than this.
  51           Setting this too low will cause a lot of warnings.
  52           Setting it to 0 disables the warning.
  53           Requires gcc 4.4
  54
  55 config MAGIC_SYSRQ
  56         bool "Magic SysRq key"
  57         depends on !UML
  58         help
  59           If you say Y here, you will have some control over the system even
  60           if the system crashes for example during kernel debugging (e.g., you
  61           will be able to flush the buffer cache to disk, reboot the system
  62           immediately or dump some status information). This is accomplished
  63           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  64           also works on a serial console (on PC hardware at least), if you
  65           send a BREAK and then within 5 seconds a command keypress. The
  66           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  67           unless you really know what this hack does.
  68
  69 config STRIP_ASM_SYMS
  70         bool "Strip assembler-generated symbols during link"
  71         default n
  72         help
  73           Strip internal assembler-generated symbols during a link (symbols
  74           that look like '.Lxxx') so they don't pollute the output of
  75           get_wchan() and suchlike.
  76
  77 config READABLE_ASM
  78         bool "Generate readable assembler code"
  79         depends on DEBUG_KERNEL
  80         help
  81           Disable some compiler optimizations that tend to generate human unreadable
  82           assembler output. This may make the kernel slightly slower, but it helps
  83           to keep kernel developers who have to stare a lot at assembler listings
  84           sane.
  85
  86 config UNUSED_SYMBOLS
  87         bool "Enable unused/obsolete exported symbols"
  88         default y if X86
  89         help
  90           Unused but exported symbols make the kernel needlessly bigger.  For
  91           that reason most of these unused exports will soon be removed.  This
  92           option is provided temporarily to provide a transition period in case
  93           some external kernel module needs one of these symbols anyway. If you
  94           encounter such a case in your module, consider if you are actually
  95           using the right API.  (rationale: since nobody in the kernel is using
  96           this in a module, there is a pretty good chance it's actually the
  97           wrong interface to use).  If you really need the symbol, please send a
  98           mail to the linux kernel mailing list mentioning the symbol and why
  99           you really need it, and what the merge plan to the mainline kernel for
 100           your module is.
 101
 102 config DEBUG_FS
 103         bool "Debug Filesystem"
 104         help
 105           debugfs is a virtual file system that kernel developers use to put
 106           debugging files into.  Enable this option to be able to read and
 107           write to these files.
 108
 109           For detailed documentation on the debugfs API, see
 110           Documentation/DocBook/filesystems.
 111
 112           If unsure, say N.
 113
 114 config HEADERS_CHECK
 115         bool "Run 'make headers_check' when building vmlinux"
 116         depends on !UML
 117         help
 118           This option will extract the user-visible kernel headers whenever
 119           building the kernel, and will run basic sanity checks on them to
 120           ensure that exported files do not attempt to include files which
 121           were not exported, etc.
 122
 123           If you're making modifications to header files which are
 124           relevant for userspace, say 'Y', and check the headers
 125           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 126           your build tree), to make sure they're suitable.
 127
 128 config DEBUG_SECTION_MISMATCH
 129         bool "Enable full Section mismatch analysis"
 130         help
 131           The section mismatch analysis checks if there are illegal
 132           references from one section to another section.
 133           During linktime or runtime, some sections are dropped;
 134           any use of code/data previously in these sections would
 135           most likely result in an oops.
 136           In the code, functions and variables are annotated with
 137           __init, __devinit, etc. (see the full list in include/linux/init.h),
 138           which results in the code/data being placed in specific sections.
 139           The section mismatch analysis is always performed after a full
 140           kernel build, and enabling this option causes the following
 141           additional steps to occur:
 142           - Add the option -fno-inline-functions-called-once to gcc commands.
 143             When inlining a function annotated with __init in a non-init
 144             function, we would lose the section information and thus
 145             the analysis would not catch the illegal reference.
 146             This option tells gcc to inline less (but it does result in
 147             a larger kernel).
 148           - Run the section mismatch analysis for each module/built-in.o file.
 149             When we run the section mismatch analysis on vmlinux.o, we
 150             lose valueble information about where the mismatch was
 151             introduced.
 152             Running the analysis for each module/built-in.o file
 153             tells where the mismatch happens much closer to the
 154             source. The drawback is that the same mismatch is
 155             reported at least twice.
 156           - Enable verbose reporting from modpost in order to help resolve
 157             the section mismatches that are reported.
 158
 159 config DEBUG_KERNEL
 160         bool "Kernel debugging"
 161         help
 162           Say Y here if you are developing drivers or trying to debug and
 163           identify kernel problems.
 164
 165 config DEBUG_SHIRQ
 166         bool "Debug shared IRQ handlers"
 167         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 168         help
 169           Enable this to generate a spurious interrupt as soon as a shared
 170           interrupt handler is registered, and just before one is deregistered.
 171           Drivers ought to be able to handle interrupts coming in at those
 172           points; some don't and need to be caught.
 173
 174 config LOCKUP_DETECTOR
 175         bool "Detect Hard and Soft Lockups"
 176         depends on DEBUG_KERNEL && !S390
 177         help
 178           Say Y here to enable the kernel to act as a watchdog to detect
 179           hard and soft lockups.
 180
 181           Softlockups are bugs that cause the kernel to loop in kernel
 182           mode for more than 20 seconds, without giving other tasks a
 183           chance to run.  The current stack trace is displayed upon
 184           detection and the system will stay locked up.
 185
 186           Hardlockups are bugs that cause the CPU to loop in kernel mode
 187           for more than 10 seconds, without letting other interrupts have a
 188           chance to run.  The current stack trace is displayed upon detection
 189           and the system will stay locked up.
 190
 191           The overhead should be minimal.  A periodic hrtimer runs to
 192           generate interrupts and kick the watchdog task every 4 seconds.
 193           An NMI is generated every 10 seconds or so to check for hardlockups.
 194
 195           The frequency of hrtimer and NMI events and the soft and hard lockup
 196           thresholds can be controlled through the sysctl watchdog_thresh.
 197
 198 config HARDLOCKUP_DETECTOR
 199         def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
 200                  !HAVE_NMI_WATCHDOG
 201
 202 config 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
 213 config 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
 220 config 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
 237 config 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
 244 config 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
 258 config 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
 264 config 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
 279 config 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
 295 config 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
 311 config 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
 318 config 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
 327 config 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
 339 config 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
 353 config 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
 361 config 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
 367 config 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
 376 config 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
 384 config 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
 392 config 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
 398 config 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
 406 config 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
 414 config 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
 422 config DEBUG_SLAB_LEAK
 423         bool "Memory leak debugging"
 424         depends on DEBUG_SLAB
 425
 426 config 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
 439 config 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
 452 config DEBUG_KMEMLEAK
 453         bool "Kernel memory leak detector"
 454         depends on DEBUG_KERNEL && EXPERIMENTAL && \
 455                 (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || \
 456                  MICROBLAZE || TILE || ARM64)
 457
 458         select DEBUG_FS
 459         select STACKTRACE if STACKTRACE_SUPPORT
 460         select KALLSYMS
 461         select CRC32
 462         help
 463           Say Y here if you want to enable the memory leak
 464           detector. The memory allocation/freeing is traced in a way
 465           similar to the Boehm's conservative garbage collector, the
 466           difference being that the orphan objects are not freed but
 467           only shown in /sys/kernel/debug/kmemleak. Enabling this
 468           feature will introduce an overhead to memory
 469           allocations. See Documentation/kmemleak.txt for more
 470           details.
 471
 472           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 473           of finding leaks due to the slab objects poisoning.
 474
 475           In order to access the kmemleak file, debugfs needs to be
 476           mounted (usually at /sys/kernel/debug).
 477
 478 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 479         int "Maximum kmemleak early log entries"
 480         depends on DEBUG_KMEMLEAK
 481         range 200 40000
 482         default 400
 483         help
 484           Kmemleak must track all the memory allocations to avoid
 485           reporting false positives. Since memory may be allocated or
 486           freed before kmemleak is initialised, an early log buffer is
 487           used to store these actions. If kmemleak reports "early log
 488           buffer exceeded", please increase this value.
 489
 490 config DEBUG_KMEMLEAK_TEST
 491         tristate "Simple test for the kernel memory leak detector"
 492         depends on DEBUG_KMEMLEAK && m
 493         help
 494           This option enables a module that explicitly leaks memory.
 495
 496           If unsure, say N.
 497
 498 config DEBUG_KMEMLEAK_DEFAULT_OFF
 499         bool "Default kmemleak to off"
 500         depends on DEBUG_KMEMLEAK
 501         help
 502           Say Y here to disable kmemleak by default. It can then be enabled
 503           on the command line via kmemleak=on.
 504
 505 config DEBUG_PREEMPT
 506         bool "Debug preemptible kernel"
 507         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 508         default y
 509         help
 510           If you say Y here then the kernel will use a debug variant of the
 511           commonly used smp_processor_id() function and will print warnings
 512           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 513           will detect preemption count underflows.
 514
 515 config DEBUG_RT_MUTEXES
 516         bool "RT Mutex debugging, deadlock detection"
 517         depends on DEBUG_KERNEL && RT_MUTEXES
 518         help
 519          This allows rt mutex semantics violations and rt mutex related
 520          deadlocks (lockups) to be detected and reported automatically.
 521
 522 config DEBUG_PI_LIST
 523         bool
 524         default y
 525         depends on DEBUG_RT_MUTEXES
 526
 527 config RT_MUTEX_TESTER
 528         bool "Built-in scriptable tester for rt-mutexes"
 529         depends on DEBUG_KERNEL && RT_MUTEXES
 530         help
 531           This option enables a rt-mutex tester.
 532
 533 config DEBUG_SPINLOCK
 534         bool "Spinlock and rw-lock debugging: basic checks"
 535         depends on DEBUG_KERNEL
 536         select UNINLINE_SPIN_UNLOCK
 537         help
 538           Say Y here and build SMP to catch missing spinlock initialization
 539           and certain other kinds of spinlock errors commonly made.  This is
 540           best used in conjunction with the NMI watchdog so that spinlock
 541           deadlocks are also debuggable.
 542
 543 config DEBUG_MUTEXES
 544         bool "Mutex debugging: basic checks"
 545         depends on DEBUG_KERNEL
 546         help
 547          This feature allows mutex semantics violations to be detected and
 548          reported.
 549
 550 config DEBUG_LOCK_ALLOC
 551         bool "Lock debugging: detect incorrect freeing of live locks"
 552         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 553         select DEBUG_SPINLOCK
 554         select DEBUG_MUTEXES
 555         select LOCKDEP
 556         help
 557          This feature will check whether any held lock (spinlock, rwlock,
 558          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 559          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 560          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 561          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 562          held during task exit.
 563
 564 config PROVE_LOCKING
 565         bool "Lock debugging: prove locking correctness"
 566         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 567         select LOCKDEP
 568         select DEBUG_SPINLOCK
 569         select DEBUG_MUTEXES
 570         select DEBUG_LOCK_ALLOC
 571         select TRACE_IRQFLAGS
 572         default n
 573         help
 574          This feature enables the kernel to prove that all locking
 575          that occurs in the kernel runtime is mathematically
 576          correct: that under no circumstance could an arbitrary (and
 577          not yet triggered) combination of observed locking
 578          sequences (on an arbitrary number of CPUs, running an
 579          arbitrary number of tasks and interrupt contexts) cause a
 580          deadlock.
 581
 582          In short, this feature enables the kernel to report locking
 583          related deadlocks before they actually occur.
 584
 585          The proof does not depend on how hard and complex a
 586          deadlock scenario would be to trigger: how many
 587          participant CPUs, tasks and irq-contexts would be needed
 588          for it to trigger. The proof also does not depend on
 589          timing: if a race and a resulting deadlock is possible
 590          theoretically (no matter how unlikely the race scenario
 591          is), it will be proven so and will immediately be
 592          reported by the kernel (once the event is observed that
 593          makes the deadlock theoretically possible).
 594
 595          If a deadlock is impossible (i.e. the locking rules, as
 596          observed by the kernel, are mathematically correct), the
 597          kernel reports nothing.
 598
 599          NOTE: this feature can also be enabled for rwlocks, mutexes
 600          and rwsems - in which case all dependencies between these
 601          different locking variants are observed and mapped too, and
 602          the proof of observed correctness is also maintained for an
 603          arbitrary combination of these separate locking variants.
 604
 605          For more details, see Documentation/lockdep-design.txt.
 606
 607 config PROVE_RCU
 608         bool "RCU debugging: prove RCU correctness"
 609         depends on PROVE_LOCKING
 610         default n
 611         help
 612          This feature enables lockdep extensions that check for correct
 613          use of RCU APIs.  This is currently under development.  Say Y
 614          if you want to debug RCU usage or help work on the PROVE_RCU
 615          feature.
 616
 617          Say N if you are unsure.
 618
 619 config PROVE_RCU_REPEATEDLY
 620         bool "RCU debugging: don't disable PROVE_RCU on first splat"
 621         depends on PROVE_RCU
 622         default n
 623         help
 624          By itself, PROVE_RCU will disable checking upon issuing the
 625          first warning (or "splat").  This feature prevents such
 626          disabling, allowing multiple RCU-lockdep warnings to be printed
 627          on a single reboot.
 628
 629          Say Y to allow multiple RCU-lockdep warnings per boot.
 630
 631          Say N if you are unsure.
 632
 633 config PROVE_RCU_DELAY
 634         bool "RCU debugging: preemptible RCU race provocation"
 635         depends on DEBUG_KERNEL && PREEMPT_RCU
 636         default n
 637         help
 638          There is a class of races that involve an unlikely preemption
 639          of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
 640          been set to INT_MIN.  This feature inserts a delay at that
 641          point to increase the probability of these races.
 642
 643          Say Y to increase probability of preemption of __rcu_read_unlock().
 644
 645          Say N if you are unsure.
 646
 647 config SPARSE_RCU_POINTER
 648         bool "RCU debugging: sparse-based checks for pointer usage"
 649         default n
 650         help
 651          This feature enables the __rcu sparse annotation for
 652          RCU-protected pointers.  This annotation will cause sparse
 653          to flag any non-RCU used of annotated pointers.  This can be
 654          helpful when debugging RCU usage.  Please note that this feature
 655          is not intended to enforce code cleanliness; it is instead merely
 656          a debugging aid.
 657
 658          Say Y to make sparse flag questionable use of RCU-protected pointers
 659
 660          Say N if you are unsure.
 661
 662 config LOCKDEP
 663         bool
 664         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 665         select STACKTRACE
 666         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 667         select KALLSYMS
 668         select KALLSYMS_ALL
 669
 670 config LOCK_STAT
 671         bool "Lock usage statistics"
 672         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 673         select LOCKDEP
 674         select DEBUG_SPINLOCK
 675         select DEBUG_MUTEXES
 676         select DEBUG_LOCK_ALLOC
 677         default n
 678         help
 679          This feature enables tracking lock contention points
 680
 681          For more details, see Documentation/lockstat.txt
 682
 683          This also enables lock events required by "perf lock",
 684          subcommand of perf.
 685          If you want to use "perf lock", you also need to turn on
 686          CONFIG_EVENT_TRACING.
 687
 688          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 689          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 690
 691 config DEBUG_LOCKDEP
 692         bool "Lock dependency engine debugging"
 693         depends on DEBUG_KERNEL && LOCKDEP
 694         help
 695           If you say Y here, the lock dependency engine will do
 696           additional runtime checks to debug itself, at the price
 697           of more runtime overhead.
 698
 699 config TRACE_IRQFLAGS
 700         bool
 701         help
 702           Enables hooks to interrupt enabling and disabling for
 703           either tracing or lock debugging.
 704
 705 config DEBUG_ATOMIC_SLEEP
 706         bool "Sleep inside atomic section checking"
 707         select PREEMPT_COUNT
 708         depends on DEBUG_KERNEL
 709         help
 710           If you say Y here, various routines which may sleep will become very
 711           noisy if they are called inside atomic sections: when a spinlock is
 712           held, inside an rcu read side critical section, inside preempt disabled
 713           sections, inside an interrupt, etc...
 714
 715 config DEBUG_LOCKING_API_SELFTESTS
 716         bool "Locking API boot-time self-tests"
 717         depends on DEBUG_KERNEL
 718         help
 719           Say Y here if you want the kernel to run a short self-test during
 720           bootup. The self-test checks whether common types of locking bugs
 721           are detected by debugging mechanisms or not. (if you disable
 722           lock debugging then those bugs wont be detected of course.)
 723           The following locking APIs are covered: spinlocks, rwlocks,
 724           mutexes and rwsems.
 725
 726 config STACKTRACE
 727         bool
 728         depends on STACKTRACE_SUPPORT
 729
 730 config DEBUG_STACK_USAGE
 731         bool "Stack utilization instrumentation"
 732         depends on DEBUG_KERNEL && !IA64 && !PARISC
 733         help
 734           Enables the display of the minimum amount of free stack which each
 735           task has ever had available in the sysrq-T and sysrq-P debug output.
 736
 737           This option will slow down process creation somewhat.
 738
 739 config DEBUG_KOBJECT
 740         bool "kobject debugging"
 741         depends on DEBUG_KERNEL
 742         help
 743           If you say Y here, some extra kobject debugging messages will be sent
 744           to the syslog.
 745
 746 config DEBUG_HIGHMEM
 747         bool "Highmem debugging"
 748         depends on DEBUG_KERNEL && HIGHMEM
 749         help
 750           This options enables addition error checking for high memory systems.
 751           Disable for production systems.
 752
 753 config DEBUG_BUGVERBOSE
 754         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
 755         depends on BUG
 756         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 757                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || \
 758                    TILE || ARM64
 759         default y
 760         help
 761           Say Y here to make BUG() panics output the file name and line number
 762           of the BUG call as well as the EIP and oops trace.  This aids
 763           debugging but costs about 70-100K of memory.
 764
 765 config DEBUG_INFO
 766         bool "Compile the kernel with debug info"
 767         depends on DEBUG_KERNEL
 768         help
 769           If you say Y here the resulting kernel image will include
 770           debugging info resulting in a larger kernel image.
 771           This adds debug symbols to the kernel and modules (gcc -g), and
 772           is needed if you intend to use kernel crashdump or binary object
 773           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 774           Say Y here only if you plan to debug the kernel.
 775
 776           If unsure, say N.
 777
 778 config DEBUG_INFO_REDUCED
 779         bool "Reduce debugging information"
 780         depends on DEBUG_INFO
 781         help
 782           If you say Y here gcc is instructed to generate less debugging
 783           information for structure types. This means that tools that
 784           need full debugging information (like kgdb or systemtap) won't
 785           be happy. But if you merely need debugging information to
 786           resolve line numbers there is no loss. Advantage is that
 787           build directory object sizes shrink dramatically over a full
 788           DEBUG_INFO build and compile times are reduced too.
 789           Only works with newer gcc versions.
 790
 791 config DEBUG_VM
 792         bool "Debug VM"
 793         depends on DEBUG_KERNEL
 794         help
 795           Enable this to turn on extended checks in the virtual-memory system
 796           that may impact performance.
 797
 798           If unsure, say N.
 799
 800 config DEBUG_VIRTUAL
 801         bool "Debug VM translations"
 802         depends on DEBUG_KERNEL && X86
 803         help
 804           Enable some costly sanity checks in virtual to page code. This can
 805           catch mistakes with virt_to_page() and friends.
 806
 807           If unsure, say N.
 808
 809 config DEBUG_NOMMU_REGIONS
 810         bool "Debug the global anon/private NOMMU mapping region tree"
 811         depends on DEBUG_KERNEL && !MMU
 812         help
 813           This option causes the global tree of anonymous and private mapping
 814           regions to be regularly checked for invalid topology.
 815
 816 config DEBUG_WRITECOUNT
 817         bool "Debug filesystem writers count"
 818         depends on DEBUG_KERNEL
 819         help
 820           Enable this to catch wrong use of the writers count in struct
 821           vfsmount.  This will increase the size of each file struct by
 822           32 bits.
 823
 824           If unsure, say N.
 825
 826 config DEBUG_MEMORY_INIT
 827         bool "Debug memory initialisation" if EXPERT
 828         default !EXPERT
 829         help
 830           Enable this for additional checks during memory initialisation.
 831           The sanity checks verify aspects of the VM such as the memory model
 832           and other information provided by the architecture. Verbose
 833           information will be printed at KERN_DEBUG loglevel depending
 834           on the mminit_loglevel= command-line option.
 835
 836           If unsure, say Y
 837
 838 config DEBUG_LIST
 839         bool "Debug linked list manipulation"
 840         depends on DEBUG_KERNEL
 841         help
 842           Enable this to turn on extended checks in the linked-list
 843           walking routines.
 844
 845           If unsure, say N.
 846
 847 config TEST_LIST_SORT
 848         bool "Linked list sorting test"
 849         depends on DEBUG_KERNEL
 850         help
 851           Enable this to turn on 'list_sort()' function test. This test is
 852           executed only once during system boot, so affects only boot time.
 853
 854           If unsure, say N.
 855
 856 config DEBUG_SG
 857         bool "Debug SG table operations"
 858         depends on DEBUG_KERNEL
 859         help
 860           Enable this to turn on checks on scatter-gather tables. This can
 861           help find problems with drivers that do not properly initialize
 862           their sg tables.
 863
 864           If unsure, say N.
 865
 866 config DEBUG_NOTIFIERS
 867         bool "Debug notifier call chains"
 868         depends on DEBUG_KERNEL
 869         help
 870           Enable this to turn on sanity checking for notifier call chains.
 871           This is most useful for kernel developers to make sure that
 872           modules properly unregister themselves from notifier chains.
 873           This is a relatively cheap check but if you care about maximum
 874           performance, say N.
 875
 876 config DEBUG_CREDENTIALS
 877         bool "Debug credential management"
 878         depends on DEBUG_KERNEL
 879         help
 880           Enable this to turn on some debug checking for credential
 881           management.  The additional code keeps track of the number of
 882           pointers from task_structs to any given cred struct, and checks to
 883           see that this number never exceeds the usage count of the cred
 884           struct.
 885
 886           Furthermore, if SELinux is enabled, this also checks that the
 887           security pointer in the cred struct is never seen to be invalid.
 888
 889           If unsure, say N.
 890
 891 #
 892 # Select this config option from the architecture Kconfig, if it
 893 # is preferred to always offer frame pointers as a config
 894 # option on the architecture (regardless of KERNEL_DEBUG):
 895 #
 896 config ARCH_WANT_FRAME_POINTERS
 897         bool
 898         help
 899
 900 config FRAME_POINTER
 901         bool "Compile the kernel with frame pointers"
 902         depends on DEBUG_KERNEL && \
 903                 (CRIS || M68K || FRV || UML || \
 904                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 905                 ARCH_WANT_FRAME_POINTERS
 906         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 907         help
 908           If you say Y here the resulting kernel image will be slightly
 909           larger and slower, but it gives very useful debugging information
 910           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 911
 912 config BOOT_PRINTK_DELAY
 913         bool "Delay each boot printk message by N milliseconds"
 914         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 915         help
 916           This build option allows you to read kernel boot messages
 917           by inserting a short delay after each one.  The delay is
 918           specified in milliseconds on the kernel command line,
 919           using "boot_delay=N".
 920
 921           It is likely that you would also need to use "lpj=M" to preset
 922           the "loops per jiffie" value.
 923           See a previous boot log for the "lpj" value to use for your
 924           system, and then set "lpj=M" before setting "boot_delay=N".
 925           NOTE:  Using this option may adversely affect SMP systems.
 926           I.e., processors other than the first one may not boot up.
 927           BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
 928           what it believes to be lockup conditions.
 929
 930 config RCU_TORTURE_TEST
 931         tristate "torture tests for RCU"
 932         depends on DEBUG_KERNEL
 933         default n
 934         help
 935           This option provides a kernel module that runs torture tests
 936           on the RCU infrastructure.  The kernel module may be built
 937           after the fact on the running kernel to be tested, if desired.
 938
 939           Say Y here if you want RCU torture tests to be built into
 940           the kernel.
 941           Say M if you want the RCU torture tests to build as a module.
 942           Say N if you are unsure.
 943
 944 config RCU_TORTURE_TEST_RUNNABLE
 945         bool "torture tests for RCU runnable by default"
 946         depends on RCU_TORTURE_TEST = y
 947         default n
 948         help
 949           This option provides a way to build the RCU torture tests
 950           directly into the kernel without them starting up at boot
 951           time.  You can use /proc/sys/kernel/rcutorture_runnable
 952           to manually override this setting.  This /proc file is
 953           available only when the RCU torture tests have been built
 954           into the kernel.
 955
 956           Say Y here if you want the RCU torture tests to start during
 957           boot (you probably don't).
 958           Say N here if you want the RCU torture tests to start only
 959           after being manually enabled via /proc.
 960
 961 config RCU_CPU_STALL_TIMEOUT
 962         int "RCU CPU stall timeout in seconds"
 963         depends on TREE_RCU || TREE_PREEMPT_RCU
 964         range 3 300
 965         default 60
 966         help
 967           If a given RCU grace period extends more than the specified
 968           number of seconds, a CPU stall warning is printed.  If the
 969           RCU grace period persists, additional CPU stall warnings are
 970           printed at more widely spaced intervals.
 971
 972 config RCU_CPU_STALL_VERBOSE
 973         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 974         depends on TREE_PREEMPT_RCU
 975         default y
 976         help
 977           This option causes RCU to printk detailed per-task information
 978           for any tasks that are stalling the current RCU grace period.
 979
 980           Say N if you are unsure.
 981
 982           Say Y if you want to enable such checks.
 983
 984 config RCU_CPU_STALL_INFO
 985         bool "Print additional diagnostics on RCU CPU stall"
 986         depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
 987         default n
 988         help
 989           For each stalled CPU that is aware of the current RCU grace
 990           period, print out additional per-CPU diagnostic information
 991           regarding scheduling-clock ticks, idle state, and,
 992           for RCU_FAST_NO_HZ kernels, idle-entry state.
 993
 994           Say N if you are unsure.
 995
 996           Say Y if you want to enable such diagnostics.
 997
 998 config RCU_TRACE
 999         bool "Enable tracing for RCU"
1000         depends on DEBUG_KERNEL
1001         help
1002           This option provides tracing in RCU which presents stats
1003           in debugfs for debugging RCU implementation.
1004
1005           Say Y here if you want to enable RCU tracing
1006           Say N if you are unsure.
1007
1008 config KPROBES_SANITY_TEST
1009         bool "Kprobes sanity tests"
1010         depends on DEBUG_KERNEL
1011         depends on KPROBES
1012         default n
1013         help
1014           This option provides for testing basic kprobes functionality on
1015           boot. A sample kprobe, jprobe and kretprobe are inserted and
1016           verified for functionality.
1017
1018           Say N if you are unsure.
1019
1020 config BACKTRACE_SELF_TEST
1021         tristate "Self test for the backtrace code"
1022         depends on DEBUG_KERNEL
1023         default n
1024         help
1025           This option provides a kernel module that can be used to test
1026           the kernel stack backtrace code. This option is not useful
1027           for distributions or general kernels, but only for kernel
1028           developers working on architecture code.
1029
1030           Note that if you want to also test saved backtraces, you will
1031           have to enable STACKTRACE as well.
1032
1033           Say N if you are unsure.
1034
1035 config DEBUG_BLOCK_EXT_DEVT
1036         bool "Force extended block device numbers and spread them"
1037         depends on DEBUG_KERNEL
1038         depends on BLOCK
1039         default n
1040         help
1041           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1042           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1043           YOU ARE DOING.  Distros, please enable this and fix whatever
1044           is broken.
1045
1046           Conventionally, block device numbers are allocated from
1047           predetermined contiguous area.  However, extended block area
1048           may introduce non-contiguous block device numbers.  This
1049           option forces most block device numbers to be allocated from
1050           the extended space and spreads them to discover kernel or
1051           userland code paths which assume predetermined contiguous
1052           device number allocation.
1053
1054           Note that turning on this debug option shuffles all the
1055           device numbers for all IDE and SCSI devices including libata
1056           ones, so root partition specified using device number
1057           directly (via rdev or root=MAJ:MIN) won't work anymore.
1058           Textual device names (root=/dev/sdXn) will continue to work.
1059
1060           Say N if you are unsure.
1061
1062 config DEBUG_FORCE_WEAK_PER_CPU
1063         bool "Force weak per-cpu definitions"
1064         depends on DEBUG_KERNEL
1065         help
1066           s390 and alpha require percpu variables in modules to be
1067           defined weak to work around addressing range issue which
1068           puts the following two restrictions on percpu variable
1069           definitions.
1070
1071           1. percpu symbols must be unique whether static or not
1072           2. percpu variables can't be defined inside a function
1073
1074           To ensure that generic code follows the above rules, this
1075           option forces all percpu variables to be defined as weak.
1076
1077 config DEBUG_PER_CPU_MAPS
1078         bool "Debug access to per_cpu maps"
1079         depends on DEBUG_KERNEL
1080         depends on SMP
1081         help
1082           Say Y to verify that the per_cpu map being accessed has
1083           been set up. This adds a fair amount of code to kernel memory
1084           and decreases performance.
1085
1086           Say N if unsure.
1087
1088 config LKDTM
1089         tristate "Linux Kernel Dump Test Tool Module"
1090         depends on DEBUG_FS
1091         depends on BLOCK
1092         default n
1093         help
1094         This module enables testing of the different dumping mechanisms by
1095         inducing system failures at predefined crash points.
1096         If you don't need it: say N
1097         Choose M here to compile this code as a module. The module will be
1098         called lkdtm.
1099
1100         Documentation on how to use the module can be found in
1101         Documentation/fault-injection/provoke-crashes.txt
1102
1103 config NOTIFIER_ERROR_INJECTION
1104         tristate "Notifier error injection"
1105         depends on DEBUG_KERNEL
1106         select DEBUG_FS
1107         help
1108           This option provides the ability to inject artifical errors to
1109           specified notifier chain callbacks. It is useful to test the error
1110           handling of notifier call chain failures.
1111
1112           Say N if unsure.
1113
1114 config CPU_NOTIFIER_ERROR_INJECT
1115         tristate "CPU notifier error injection module"
1116         depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1117         help
1118           This option provides a kernel module that can be used to test
1119           the error handling of the cpu notifiers by injecting artifical
1120           errors to CPU notifier chain callbacks.  It is controlled through
1121           debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1122
1123           If the notifier call chain should be failed with some events
1124           notified, write the error code to "actions/<notifier event>/error".
1125
1126           Example: Inject CPU offline error (-1 == -EPERM)
1127
1128           # cd /sys/kernel/debug/notifier-error-inject/cpu
1129           # echo -1 > actions/CPU_DOWN_PREPARE/error
1130           # echo 0 > /sys/devices/system/cpu/cpu1/online
1131           bash: echo: write error: Operation not permitted
1132
1133           To compile this code as a module, choose M here: the module will
1134           be called cpu-notifier-error-inject.
1135
1136           If unsure, say N.
1137
1138 config PM_NOTIFIER_ERROR_INJECT
1139         tristate "PM notifier error injection module"
1140         depends on PM && NOTIFIER_ERROR_INJECTION
1141         default m if PM_DEBUG
1142         help
1143           This option provides the ability to inject artifical errors to
1144           PM notifier chain callbacks.  It is controlled through debugfs
1145           interface /sys/kernel/debug/notifier-error-inject/pm
1146
1147           If the notifier call chain should be failed with some events
1148           notified, write the error code to "actions/<notifier event>/error".
1149
1150           Example: Inject PM suspend error (-12 = -ENOMEM)
1151
1152           # cd /sys/kernel/debug/notifier-error-inject/pm/
1153           # echo -12 > actions/PM_SUSPEND_PREPARE/error
1154           # echo mem > /sys/power/state
1155           bash: echo: write error: Cannot allocate memory
1156
1157           To compile this code as a module, choose M here: the module will
1158           be called pm-notifier-error-inject.
1159
1160           If unsure, say N.
1161
1162 config MEMORY_NOTIFIER_ERROR_INJECT
1163         tristate "Memory hotplug notifier error injection module"
1164         depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1165         help
1166           This option provides the ability to inject artifical errors to
1167           memory hotplug notifier chain callbacks.  It is controlled through
1168           debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
1169
1170           If the notifier call chain should be failed with some events
1171           notified, write the error code to "actions/<notifier event>/error".
1172
1173           Example: Inject memory hotplug offline error (-12 == -ENOMEM)
1174
1175           # cd /sys/kernel/debug/notifier-error-inject/memory
1176           # echo -12 > actions/MEM_GOING_OFFLINE/error
1177           # echo offline > /sys/devices/system/memory/memoryXXX/state
1178           bash: echo: write error: Cannot allocate memory
1179
1180           To compile this code as a module, choose M here: the module will
1181           be called pSeries-reconfig-notifier-error-inject.
1182
1183           If unsure, say N.
1184
1185 config PSERIES_RECONFIG_NOTIFIER_ERROR_INJECT
1186         tristate "pSeries reconfig notifier error injection module"
1187         depends on PPC_PSERIES && NOTIFIER_ERROR_INJECTION
1188         help
1189           This option provides the ability to inject artifical errors to
1190           pSeries reconfig notifier chain callbacks.  It is controlled
1191           through debugfs interface under
1192           /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/
1193
1194           If the notifier call chain should be failed with some events
1195           notified, write the error code to "actions/<notifier event>/error".
1196
1197           To compile this code as a module, choose M here: the module will
1198           be called memory-notifier-error-inject.
1199
1200           If unsure, say N.
1201
1202 config FAULT_INJECTION
1203         bool "Fault-injection framework"
1204         depends on DEBUG_KERNEL
1205         help
1206           Provide fault-injection framework.
1207           For more details, see Documentation/fault-injection/.
1208
1209 config FAILSLAB
1210         bool "Fault-injection capability for kmalloc"
1211         depends on FAULT_INJECTION
1212         depends on SLAB || SLUB
1213         help
1214           Provide fault-injection capability for kmalloc.
1215
1216 config FAIL_PAGE_ALLOC
1217         bool "Fault-injection capabilitiy for alloc_pages()"
1218         depends on FAULT_INJECTION
1219         help
1220           Provide fault-injection capability for alloc_pages().
1221
1222 config FAIL_MAKE_REQUEST
1223         bool "Fault-injection capability for disk IO"
1224         depends on FAULT_INJECTION && BLOCK
1225         help
1226           Provide fault-injection capability for disk IO.
1227
1228 config FAIL_IO_TIMEOUT
1229         bool "Fault-injection capability for faking disk interrupts"
1230         depends on FAULT_INJECTION && BLOCK
1231         help
1232           Provide fault-injection capability on end IO handling. This
1233           will make the block layer "forget" an interrupt as configured,
1234           thus exercising the error handling.
1235
1236           Only works with drivers that use the generic timeout handling,
1237           for others it wont do anything.
1238
1239 config FAIL_MMC_REQUEST
1240         bool "Fault-injection capability for MMC IO"
1241         select DEBUG_FS
1242         depends on FAULT_INJECTION && MMC
1243         help
1244           Provide fault-injection capability for MMC IO.
1245           This will make the mmc core return data errors. This is
1246           useful to test the error handling in the mmc block device
1247           and to test how the mmc host driver handles retries from
1248           the block device.
1249
1250 config FAULT_INJECTION_DEBUG_FS
1251         bool "Debugfs entries for fault-injection capabilities"
1252         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1253         help
1254           Enable configuration of fault-injection capabilities via debugfs.
1255
1256 config FAULT_INJECTION_STACKTRACE_FILTER
1257         bool "stacktrace filter for fault-injection capabilities"
1258         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1259         depends on !X86_64
1260         select STACKTRACE
1261         select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1262         help
1263           Provide stacktrace filter for fault-injection capabilities
1264
1265 config LATENCYTOP
1266         bool "Latency measuring infrastructure"
1267         depends on HAVE_LATENCYTOP_SUPPORT
1268         depends on DEBUG_KERNEL
1269         depends on STACKTRACE_SUPPORT
1270         depends on PROC_FS
1271         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1272         select KALLSYMS
1273         select KALLSYMS_ALL
1274         select STACKTRACE
1275         select SCHEDSTATS
1276         select SCHED_DEBUG
1277         help
1278           Enable this option if you want to use the LatencyTOP tool
1279           to find out which userspace is blocking on what kernel operations.
1280
1281 source mm/Kconfig.debug
1282 source kernel/trace/Kconfig
1283
1284 config PROVIDE_OHCI1394_DMA_INIT
1285         bool "Remote debugging over FireWire early on boot"
1286         depends on PCI && X86
1287         help
1288           If you want to debug problems which hang or crash the kernel early
1289           on boot and the crashing machine has a FireWire port, you can use
1290           this feature to remotely access the memory of the crashed machine
1291           over FireWire. This employs remote DMA as part of the OHCI1394
1292           specification which is now the standard for FireWire controllers.
1293
1294           With remote DMA, you can monitor the printk buffer remotely using
1295           firescope and access all memory below 4GB using fireproxy from gdb.
1296           Even controlling a kernel debugger is possible using remote DMA.
1297
1298           Usage:
1299
1300           If ohci1394_dma=early is used as boot parameter, it will initialize
1301           all OHCI1394 controllers which are found in the PCI config space.
1302
1303           As all changes to the FireWire bus such as enabling and disabling
1304           devices cause a bus reset and thereby disable remote DMA for all
1305           devices, be sure to have the cable plugged and FireWire enabled on
1306           the debugging host before booting the debug target for debugging.
1307
1308           This code (~1k) is freed after boot. By then, the firewire stack
1309           in charge of the OHCI-1394 controllers should be used instead.
1310
1311           See Documentation/debugging-via-ohci1394.txt for more information.
1312
1313 config FIREWIRE_OHCI_REMOTE_DMA
1314         bool "Remote debugging over FireWire with firewire-ohci"
1315         depends on FIREWIRE_OHCI
1316         help
1317           This option lets you use the FireWire bus for remote debugging
1318           with help of the firewire-ohci driver. It enables unfiltered
1319           remote DMA in firewire-ohci.
1320           See Documentation/debugging-via-ohci1394.txt for more information.
1321
1322           If unsure, say N.
1323
1324 config BUILD_DOCSRC
1325         bool "Build targets in Documentation/ tree"
1326         depends on HEADERS_CHECK
1327         help
1328           This option attempts to build objects from the source files in the
1329           kernel Documentation/ tree.
1330
1331           Say N if you are unsure.
1332
1333 config DYNAMIC_DEBUG
1334         bool "Enable dynamic printk() support"
1335         default n
1336         depends on PRINTK
1337         depends on DEBUG_FS
1338         help
1339
1340           Compiles debug level messages into the kernel, which would not
1341           otherwise be available at runtime. These messages can then be
1342           enabled/disabled based on various levels of scope - per source file,
1343           function, module, format string, and line number. This mechanism
1344           implicitly compiles in all pr_debug() and dev_dbg() calls, which
1345           enlarges the kernel text size by about 2%.
1346
1347           If a source file is compiled with DEBUG flag set, any
1348           pr_debug() calls in it are enabled by default, but can be
1349           disabled at runtime as below.  Note that DEBUG flag is
1350           turned on by many CONFIG_*DEBUG* options.
1351
1352           Usage:
1353
1354           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1355           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1356           filesystem must first be mounted before making use of this feature.
1357           We refer the control file as: <debugfs>/dynamic_debug/control. This
1358           file contains a list of the debug statements that can be enabled. The
1359           format for each line of the file is:
1360
1361                 filename:lineno [module]function flags format
1362
1363           filename : source file of the debug statement
1364           lineno : line number of the debug statement
1365           module : module that contains the debug statement
1366           function : function that contains the debug statement
1367           flags : '=p' means the line is turned 'on' for printing
1368           format : the format used for the debug statement
1369
1370           From a live system:
1371
1372                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1373                 # filename:lineno [module]function flags format
1374                 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1375                 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1376                 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
1377
1378           Example usage:
1379
1380                 // enable the message at line 1603 of file svcsock.c
1381                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1382                                                 <debugfs>/dynamic_debug/control
1383
1384                 // enable all the messages in file svcsock.c
1385                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1386                                                 <debugfs>/dynamic_debug/control
1387
1388                 // enable all the messages in the NFS server module
1389                 nullarbor:~ # echo -n 'module nfsd +p' >
1390                                                 <debugfs>/dynamic_debug/control
1391
1392                 // enable all 12 messages in the function svc_process()
1393                 nullarbor:~ # echo -n 'func svc_process +p' >
1394                                                 <debugfs>/dynamic_debug/control
1395
1396                 // disable all 12 messages in the function svc_process()
1397                 nullarbor:~ # echo -n 'func svc_process -p' >
1398                                                 <debugfs>/dynamic_debug/control
1399
1400           See Documentation/dynamic-debug-howto.txt for additional information.
1401
1402 config DMA_API_DEBUG
1403         bool "Enable debugging of DMA-API usage"
1404         depends on HAVE_DMA_API_DEBUG
1405         help
1406           Enable this option to debug the use of the DMA API by device drivers.
1407           With this option you will be able to detect common bugs in device
1408           drivers like double-freeing of DMA mappings or freeing mappings that
1409           were never allocated.
1410           This option causes a performance degredation.  Use only if you want
1411           to debug device drivers. If unsure, say N.
1412
1413 config ATOMIC64_SELFTEST
1414         bool "Perform an atomic64_t self-test at boot"
1415         help
1416           Enable this option to test the atomic64_t functions at boot.
1417
1418           If unsure, say N.
1419
1420 config ASYNC_RAID6_TEST
1421         tristate "Self test for hardware accelerated raid6 recovery"
1422         depends on ASYNC_RAID6_RECOV
1423         select ASYNC_MEMCPY
1424         ---help---
1425           This is a one-shot self test that permutes through the
1426           recovery of all the possible two disk failure scenarios for a
1427           N-disk array.  Recovery is performed with the asynchronous
1428           raid6 recovery routines, and will optionally use an offload
1429           engine if one is available.
1430
1431           If unsure, say N.
1432
1433 source "samples/Kconfig"
1434
1435 source "lib/Kconfig.kgdb"
1436
1437 source "lib/Kconfig.kmemcheck"
1438
1439 config TEST_KSTRTOX
1440         tristate "Test kstrto*() family of functions at runtime"