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, __cpuinit, etc. (see the full list in include/linux/init.h),
 138           which results in the code/data being placed in specific sections.
 139           The section mismatch analysis is always performed after a full
 140           kernel build, and enabling this option causes the following
 141           additional steps to occur:
 142           - Add the option -fno-inline-functions-called-once to gcc commands.
 143             When inlining a function annotated with __init in a non-init
 144             function, we would lose the section information and thus
 145             the analysis would not catch the illegal reference.
 146             This option tells gcc to inline less (but it does result in
 147             a larger kernel).
 148           - Run the section mismatch analysis for each module/built-in.o file.
 149             When we run the section mismatch analysis on vmlinux.o, we
 150             lose valueble information about where the mismatch was
 151             introduced.
 152             Running the analysis for each module/built-in.o file
 153             tells where the mismatch happens much closer to the
 154             source. The drawback is that the same mismatch is
 155             reported at least twice.
 156           - Enable verbose reporting from modpost in order to help resolve
 157             the section mismatches that are reported.
 158
 159 config DEBUG_KERNEL
 160         bool "Kernel debugging"
 161         help
 162           Say Y here if you are developing drivers or trying to debug and
 163           identify kernel problems.
 164
 165 config DEBUG_SHIRQ
 166         bool "Debug shared IRQ handlers"
 167         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 168         help
 169           Enable this to generate a spurious interrupt as soon as a shared
 170           interrupt handler is registered, and just before one is deregistered.
 171           Drivers ought to be able to handle interrupts coming in at those
 172           points; some don't and need to be caught.
 173
 174 config LOCKUP_DETECTOR
 175         bool "Detect Hard and Soft Lockups"
 176         depends on DEBUG_KERNEL && !S390
 177         help
 178           Say Y here to enable the kernel to act as a watchdog to detect
 179           hard and soft lockups.
 180
 181           Softlockups are bugs that cause the kernel to loop in kernel
 182           mode for more than 20 seconds, without giving other tasks a
 183           chance to run.  The current stack trace is displayed upon
 184           detection and the system will stay locked up.
 185
 186           Hardlockups are bugs that cause the CPU to loop in kernel mode
 187           for more than 10 seconds, without letting other interrupts have a
 188           chance to run.  The current stack trace is displayed upon detection
 189           and the system will stay locked up.
 190
 191           The overhead should be minimal.  A periodic hrtimer runs to
 192           generate interrupts and kick the watchdog task every 4 seconds.
 193           An NMI is generated every 10 seconds or so to check for hardlockups.
 194
 195           The frequency of hrtimer and NMI events and the soft and hard lockup
 196           thresholds can be controlled through the sysctl watchdog_thresh.
 197
 198 config HARDLOCKUP_DETECTOR
 199         def_bool y
 200         depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
 201         depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
 202
 203 config BOOTPARAM_HARDLOCKUP_PANIC
 204         bool "Panic (Reboot) On Hard Lockups"
 205         depends on HARDLOCKUP_DETECTOR
 206         help
 207           Say Y here to enable the kernel to panic on "hard lockups",
 208           which are bugs that cause the kernel to loop in kernel
 209           mode with interrupts disabled for more than 10 seconds (configurable
 210           using the watchdog_thresh sysctl).
 211
 212           Say N if unsure.
 213
 214 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
 215         int
 216         depends on HARDLOCKUP_DETECTOR
 217         range 0 1
 218         default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
 219         default 1 if BOOTPARAM_HARDLOCKUP_PANIC
 220
 221 config BOOTPARAM_SOFTLOCKUP_PANIC
 222         bool "Panic (Reboot) On Soft Lockups"
 223         depends on LOCKUP_DETECTOR
 224         help
 225           Say Y here to enable the kernel to panic on "soft lockups",
 226           which are bugs that cause the kernel to loop in kernel
 227           mode for more than 20 seconds (configurable using the watchdog_thresh
 228           sysctl), without giving other tasks a chance to run.
 229
 230           The panic can be used in combination with panic_timeout,
 231           to cause the system to reboot automatically after a
 232           lockup has been detected. This feature is useful for
 233           high-availability systems that have uptime guarantees and
 234           where a lockup must be resolved ASAP.
 235
 236           Say N if unsure.
 237
 238 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 239         int
 240         depends on LOCKUP_DETECTOR
 241         range 0 1
 242         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 243         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 244
 245 config PANIC_ON_OOPS
 246         bool "Panic on Oops" if EXPERT
 247         default n
 248         help
 249           Say Y here to enable the kernel to panic when it oopses. This
 250           has the same effect as setting oops=panic on the kernel command
 251           line.
 252
 253           This feature is useful to ensure that the kernel does not do
 254           anything erroneous after an oops which could result in data
 255           corruption or other issues.
 256
 257           Say N if unsure.
 258
 259 config PANIC_ON_OOPS_VALUE
 260         int
 261         range 0 1
 262         default 0 if !PANIC_ON_OOPS
 263         default 1 if PANIC_ON_OOPS
 264
 265 config DETECT_HUNG_TASK
 266         bool "Detect Hung Tasks"
 267         depends on DEBUG_KERNEL
 268         default LOCKUP_DETECTOR
 269         help
 270           Say Y here to enable the kernel to detect "hung tasks",
 271           which are bugs that cause the task to be stuck in
 272           uninterruptible "D" state indefinitiley.
 273
 274           When a hung task is detected, the kernel will print the
 275           current stack trace (which you should report), but the
 276           task will stay in uninterruptible state. If lockdep is
 277           enabled then all held locks will also be reported. This
 278           feature has negligible overhead.
 279
 280 config DEFAULT_HUNG_TASK_TIMEOUT
 281         int "Default timeout for hung task detection (in seconds)"
 282         depends on DETECT_HUNG_TASK
 283         default 120
 284         help
 285           This option controls the default timeout (in seconds) used
 286           to determine when a task has become non-responsive and should
 287           be considered hung.
 288
 289           It can be adjusted at runtime via the kernel.hung_task_timeout_secs
 290           sysctl or by writing a value to
 291           /proc/sys/kernel/hung_task_timeout_secs.
 292
 293           A timeout of 0 disables the check.  The default is two minutes.
 294           Keeping the default should be fine in most cases.
 295
 296 config BOOTPARAM_HUNG_TASK_PANIC
 297         bool "Panic (Reboot) On Hung Tasks"
 298         depends on DETECT_HUNG_TASK
 299         help
 300           Say Y here to enable the kernel to panic on "hung tasks",
 301           which are bugs that cause the kernel to leave a task stuck
 302           in uninterruptible "D" state.
 303
 304           The panic can be used in combination with panic_timeout,
 305           to cause the system to reboot automatically after a
 306           hung task has been detected. This feature is useful for
 307           high-availability systems that have uptime guarantees and
 308           where a hung tasks must be resolved ASAP.
 309
 310           Say N if unsure.
 311
 312 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 313         int
 314         depends on DETECT_HUNG_TASK
 315         range 0 1
 316         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 317         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 318
 319 config SCHED_DEBUG
 320         bool "Collect scheduler debugging info"
 321         depends on DEBUG_KERNEL && PROC_FS
 322         default y
 323         help
 324           If you say Y here, the /proc/sched_debug file will be provided
 325           that can help debug the scheduler. The runtime overhead of this
 326           option is minimal.
 327
 328 config SCHEDSTATS
 329         bool "Collect scheduler statistics"
 330         depends on DEBUG_KERNEL && PROC_FS
 331         help
 332           If you say Y here, additional code will be inserted into the
 333           scheduler and related routines to collect statistics about
 334           scheduler behavior and provide them in /proc/schedstat.  These
 335           stats may be useful for both tuning and debugging the scheduler
 336           If you aren't debugging the scheduler or trying to tune a specific
 337           application, you can say N to avoid the very slight overhead
 338           this adds.
 339
 340 config TIMER_STATS
 341         bool "Collect kernel timers statistics"
 342         depends on DEBUG_KERNEL && PROC_FS
 343         help
 344           If you say Y here, additional code will be inserted into the
 345           timer routines to collect statistics about kernel timers being
 346           reprogrammed. The statistics can be read from /proc/timer_stats.
 347           The statistics collection is started by writing 1 to /proc/timer_stats,
 348           writing 0 stops it. This feature is useful to collect information
 349           about timer usage patterns in kernel and userspace. This feature
 350           is lightweight if enabled in the kernel config but not activated
 351           (it defaults to deactivated on bootup and will only be activated
 352           if some application like powertop activates it explicitly).
 353
 354 config DEBUG_OBJECTS
 355         bool "Debug object operations"
 356         depends on DEBUG_KERNEL
 357         help
 358           If you say Y here, additional code will be inserted into the
 359           kernel to track the life time of various objects and validate
 360           the operations on those objects.
 361
 362 config DEBUG_OBJECTS_SELFTEST
 363         bool "Debug objects selftest"
 364         depends on DEBUG_OBJECTS
 365         help
 366           This enables the selftest of the object debug code.
 367
 368 config DEBUG_OBJECTS_FREE
 369         bool "Debug objects in freed memory"
 370         depends on DEBUG_OBJECTS
 371         help
 372           This enables checks whether a k/v free operation frees an area
 373           which contains an object which has not been deactivated
 374           properly. This can make kmalloc/kfree-intensive workloads
 375           much slower.
 376
 377 config DEBUG_OBJECTS_TIMERS
 378         bool "Debug timer objects"
 379         depends on DEBUG_OBJECTS
 380         help
 381           If you say Y here, additional code will be inserted into the
 382           timer routines to track the life time of timer objects and
 383           validate the timer operations.
 384
 385 config DEBUG_OBJECTS_WORK
 386         bool "Debug work objects"
 387         depends on DEBUG_OBJECTS
 388         help
 389           If you say Y here, additional code will be inserted into the
 390           work queue routines to track the life time of work objects and
 391           validate the work operations.
 392
 393 config DEBUG_OBJECTS_RCU_HEAD
 394         bool "Debug RCU callbacks objects"
 395         depends on DEBUG_OBJECTS
 396         help
 397           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 398
 399 config DEBUG_OBJECTS_PERCPU_COUNTER
 400         bool "Debug percpu counter objects"
 401         depends on DEBUG_OBJECTS
 402         help
 403           If you say Y here, additional code will be inserted into the
 404           percpu counter routines to track the life time of percpu counter
 405           objects and validate the percpu counter operations.
 406
 407 config DEBUG_OBJECTS_ENABLE_DEFAULT
 408         int "debug_objects bootup default value (0-1)"
 409         range 0 1
 410         default "1"
 411         depends on DEBUG_OBJECTS
 412         help
 413           Debug objects boot parameter default value
 414
 415 config DEBUG_SLAB
 416         bool "Debug slab memory allocations"
 417         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 418         help
 419           Say Y here to have the kernel do limited verification on memory
 420           allocation as well as poisoning memory on free to catch use of freed
 421           memory. This can make kmalloc/kfree-intensive workloads much slower.
 422
 423 config DEBUG_SLAB_LEAK
 424         bool "Memory leak debugging"
 425         depends on DEBUG_SLAB
 426
 427 config SLUB_DEBUG_ON
 428         bool "SLUB debugging on by default"
 429         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 430         default n
 431         help
 432           Boot with debugging on by default. SLUB boots by default with
 433           the runtime debug capabilities switched off. Enabling this is
 434           equivalent to specifying the "slub_debug" parameter on boot.
 435           There is no support for more fine grained debug control like
 436           possible with slub_debug=xxx. SLUB debugging may be switched
 437           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 438           "slub_debug=-".
 439
 440 config SLUB_STATS
 441         default n
 442         bool "Enable SLUB performance statistics"
 443         depends on SLUB && SYSFS
 444         help
 445           SLUB statistics are useful to debug SLUBs allocation behavior in
 446           order find ways to optimize the allocator. This should never be
 447           enabled for production use since keeping statistics slows down
 448           the allocator by a few percentage points. The slabinfo command
 449           supports the determination of the most active slabs to figure
 450           out which slabs are relevant to a particular load.
 451           Try running: slabinfo -DA
 452
 453 config HAVE_DEBUG_KMEMLEAK
 454         bool
 455
 456 config DEBUG_KMEMLEAK
 457         bool "Kernel memory leak detector"
 458         depends on DEBUG_KERNEL && EXPERIMENTAL && HAVE_DEBUG_KMEMLEAK
 459         select DEBUG_FS
 460         select STACKTRACE if STACKTRACE_SUPPORT
 461         select KALLSYMS
 462         select CRC32
 463         help
 464           Say Y here if you want to enable the memory leak
 465           detector. The memory allocation/freeing is traced in a way
 466           similar to the Boehm's conservative garbage collector, the
 467           difference being that the orphan objects are not freed but
 468           only shown in /sys/kernel/debug/kmemleak. Enabling this
 469           feature will introduce an overhead to memory
 470           allocations. See Documentation/kmemleak.txt for more
 471           details.
 472
 473           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 474           of finding leaks due to the slab objects poisoning.
 475
 476           In order to access the kmemleak file, debugfs needs to be
 477           mounted (usually at /sys/kernel/debug).
 478
 479 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 480         int "Maximum kmemleak early log entries"
 481         depends on DEBUG_KMEMLEAK
 482         range 200 40000
 483         default 400
 484         help
 485           Kmemleak must track all the memory allocations to avoid
 486           reporting false positives. Since memory may be allocated or
 487           freed before kmemleak is initialised, an early log buffer is
 488           used to store these actions. If kmemleak reports "early log
 489           buffer exceeded", please increase this value.
 490
 491 config DEBUG_KMEMLEAK_TEST
 492         tristate "Simple test for the kernel memory leak detector"
 493         depends on DEBUG_KMEMLEAK && m
 494         help
 495           This option enables a module that explicitly leaks memory.
 496
 497           If unsure, say N.
 498
 499 config DEBUG_KMEMLEAK_DEFAULT_OFF
 500         bool "Default kmemleak to off"
 501         depends on DEBUG_KMEMLEAK
 502         help
 503           Say Y here to disable kmemleak by default. It can then be enabled
 504           on the command line via kmemleak=on.
 505
 506 config DEBUG_PREEMPT
 507         bool "Debug preemptible kernel"
 508         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 509         default y
 510         help
 511           If you say Y here then the kernel will use a debug variant of the
 512           commonly used smp_processor_id() function and will print warnings
 513           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 514           will detect preemption count underflows.
 515
 516 config DEBUG_RT_MUTEXES
 517         bool "RT Mutex debugging, deadlock detection"
 518         depends on DEBUG_KERNEL && RT_MUTEXES
 519         help
 520          This allows rt mutex semantics violations and rt mutex related
 521          deadlocks (lockups) to be detected and reported automatically.
 522
 523 config DEBUG_PI_LIST
 524         bool
 525         default y
 526         depends on DEBUG_RT_MUTEXES
 527
 528 config RT_MUTEX_TESTER
 529         bool "Built-in scriptable tester for rt-mutexes"
 530         depends on DEBUG_KERNEL && RT_MUTEXES
 531         help
 532           This option enables a rt-mutex tester.
 533
 534 config DEBUG_SPINLOCK
 535         bool "Spinlock and rw-lock debugging: basic checks"
 536         depends on DEBUG_KERNEL
 537         select UNINLINE_SPIN_UNLOCK
 538         help
 539           Say Y here and build SMP to catch missing spinlock initialization
 540           and certain other kinds of spinlock errors commonly made.  This is
 541           best used in conjunction with the NMI watchdog so that spinlock
 542           deadlocks are also debuggable.
 543
 544 config DEBUG_MUTEXES
 545         bool "Mutex debugging: basic checks"
 546         depends on DEBUG_KERNEL
 547         help
 548          This feature allows mutex semantics violations to be detected and
 549          reported.
 550
 551 config DEBUG_LOCK_ALLOC
 552         bool "Lock debugging: detect incorrect freeing of live locks"
 553         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 554         select DEBUG_SPINLOCK
 555         select DEBUG_MUTEXES
 556         select LOCKDEP
 557         help
 558          This feature will check whether any held lock (spinlock, rwlock,
 559          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 560          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 561          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 562          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 563          held during task exit.
 564
 565 config PROVE_LOCKING
 566         bool "Lock debugging: prove locking correctness"
 567         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 568         select LOCKDEP
 569         select DEBUG_SPINLOCK
 570         select DEBUG_MUTEXES
 571         select DEBUG_LOCK_ALLOC
 572         select TRACE_IRQFLAGS
 573         default n
 574         help
 575          This feature enables the kernel to prove that all locking
 576          that occurs in the kernel runtime is mathematically
 577          correct: that under no circumstance could an arbitrary (and
 578          not yet triggered) combination of observed locking
 579          sequences (on an arbitrary number of CPUs, running an
 580          arbitrary number of tasks and interrupt contexts) cause a
 581          deadlock.
 582
 583          In short, this feature enables the kernel to report locking
 584          related deadlocks before they actually occur.
 585
 586          The proof does not depend on how hard and complex a
 587          deadlock scenario would be to trigger: how many
 588          participant CPUs, tasks and irq-contexts would be needed
 589          for it to trigger. The proof also does not depend on
 590          timing: if a race and a resulting deadlock is possible
 591          theoretically (no matter how unlikely the race scenario
 592          is), it will be proven so and will immediately be
 593          reported by the kernel (once the event is observed that
 594          makes the deadlock theoretically possible).
 595
 596          If a deadlock is impossible (i.e. the locking rules, as
 597          observed by the kernel, are mathematically correct), the
 598          kernel reports nothing.
 599
 600          NOTE: this feature can also be enabled for rwlocks, mutexes
 601          and rwsems - in which case all dependencies between these
 602          different locking variants are observed and mapped too, and
 603          the proof of observed correctness is also maintained for an
 604          arbitrary combination of these separate locking variants.
 605
 606          For more details, see Documentation/lockdep-design.txt.
 607
 608 config LOCKDEP
 609         bool
 610         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 611         select STACKTRACE
 612         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 613         select KALLSYMS
 614         select KALLSYMS_ALL
 615
 616 config LOCK_STAT
 617         bool "Lock usage statistics"
 618         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 619         select LOCKDEP
 620         select DEBUG_SPINLOCK
 621         select DEBUG_MUTEXES
 622         select DEBUG_LOCK_ALLOC
 623         default n
 624         help
 625          This feature enables tracking lock contention points
 626
 627          For more details, see Documentation/lockstat.txt
 628
 629          This also enables lock events required by "perf lock",
 630          subcommand of perf.
 631          If you want to use "perf lock", you also need to turn on
 632          CONFIG_EVENT_TRACING.
 633
 634          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 635          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 636
 637 config DEBUG_LOCKDEP
 638         bool "Lock dependency engine debugging"
 639         depends on DEBUG_KERNEL && LOCKDEP
 640         help
 641           If you say Y here, the lock dependency engine will do
 642           additional runtime checks to debug itself, at the price
 643           of more runtime overhead.
 644
 645 config TRACE_IRQFLAGS
 646         bool
 647         help
 648           Enables hooks to interrupt enabling and disabling for
 649           either tracing or lock debugging.
 650
 651 config DEBUG_ATOMIC_SLEEP
 652         bool "Sleep inside atomic section checking"
 653         select PREEMPT_COUNT
 654         depends on DEBUG_KERNEL
 655         help
 656           If you say Y here, various routines which may sleep will become very
 657           noisy if they are called inside atomic sections: when a spinlock is
 658           held, inside an rcu read side critical section, inside preempt disabled
 659           sections, inside an interrupt, etc...
 660
 661 config DEBUG_LOCKING_API_SELFTESTS
 662         bool "Locking API boot-time self-tests"
 663         depends on DEBUG_KERNEL
 664         help
 665           Say Y here if you want the kernel to run a short self-test during
 666           bootup. The self-test checks whether common types of locking bugs
 667           are detected by debugging mechanisms or not. (if you disable
 668           lock debugging then those bugs wont be detected of course.)
 669           The following locking APIs are covered: spinlocks, rwlocks,
 670           mutexes and rwsems.
 671
 672 config STACKTRACE
 673         bool
 674         depends on STACKTRACE_SUPPORT
 675
 676 config DEBUG_STACK_USAGE
 677         bool "Stack utilization instrumentation"
 678         depends on DEBUG_KERNEL && !IA64 && !PARISC
 679         help
 680           Enables the display of the minimum amount of free stack which each
 681           task has ever had available in the sysrq-T and sysrq-P debug output.
 682
 683           This option will slow down process creation somewhat.
 684
 685 config DEBUG_KOBJECT
 686         bool "kobject debugging"
 687         depends on DEBUG_KERNEL
 688         help
 689           If you say Y here, some extra kobject debugging messages will be sent
 690           to the syslog.
 691
 692 config DEBUG_HIGHMEM
 693         bool "Highmem debugging"
 694         depends on DEBUG_KERNEL && HIGHMEM
 695         help
 696           This options enables addition error checking for high memory systems.
 697           Disable for production systems.
 698
 699 config HAVE_DEBUG_BUGVERBOSE
 700         bool
 701
 702 config DEBUG_BUGVERBOSE
 703         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
 704         depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
 705         default y
 706         help
 707           Say Y here to make BUG() panics output the file name and line number
 708           of the BUG call as well as the EIP and oops trace.  This aids
 709           debugging but costs about 70-100K of memory.
 710
 711 config DEBUG_INFO
 712         bool "Compile the kernel with debug info"
 713         depends on DEBUG_KERNEL
 714         help
 715           If you say Y here the resulting kernel image will include
 716           debugging info resulting in a larger kernel image.
 717           This adds debug symbols to the kernel and modules (gcc -g), and
 718           is needed if you intend to use kernel crashdump or binary object
 719           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 720           Say Y here only if you plan to debug the kernel.
 721
 722           If unsure, say N.
 723
 724 config DEBUG_INFO_REDUCED
 725         bool "Reduce debugging information"
 726         depends on DEBUG_INFO
 727         help
 728           If you say Y here gcc is instructed to generate less debugging
 729           information for structure types. This means that tools that
 730           need full debugging information (like kgdb or systemtap) won't
 731           be happy. But if you merely need debugging information to
 732           resolve line numbers there is no loss. Advantage is that
 733           build directory object sizes shrink dramatically over a full
 734           DEBUG_INFO build and compile times are reduced too.
 735           Only works with newer gcc versions.
 736
 737 config DEBUG_VM
 738         bool "Debug VM"
 739         depends on DEBUG_KERNEL
 740         help
 741           Enable this to turn on extended checks in the virtual-memory system
 742           that may impact performance.
 743
 744           If unsure, say N.
 745
 746 config DEBUG_VM_RB
 747         bool "Debug VM red-black trees"
 748         depends on DEBUG_VM
 749         help
 750           Enable this to turn on more extended checks in the virtual-memory
 751           system that may impact performance.
 752
 753           If unsure, say N.
 754
 755 config DEBUG_VIRTUAL
 756         bool "Debug VM translations"
 757         depends on DEBUG_KERNEL && X86
 758         help
 759           Enable some costly sanity checks in virtual to page code. This can
 760           catch mistakes with virt_to_page() and friends.
 761
 762           If unsure, say N.
 763
 764 config DEBUG_NOMMU_REGIONS
 765         bool "Debug the global anon/private NOMMU mapping region tree"
 766         depends on DEBUG_KERNEL && !MMU
 767         help
 768           This option causes the global tree of anonymous and private mapping
 769           regions to be regularly checked for invalid topology.
 770
 771 config DEBUG_WRITECOUNT
 772         bool "Debug filesystem writers count"
 773         depends on DEBUG_KERNEL
 774         help
 775           Enable this to catch wrong use of the writers count in struct
 776           vfsmount.  This will increase the size of each file struct by
 777           32 bits.
 778
 779           If unsure, say N.
 780
 781 config DEBUG_MEMORY_INIT
 782         bool "Debug memory initialisation" if EXPERT
 783         default !EXPERT
 784         help
 785           Enable this for additional checks during memory initialisation.
 786           The sanity checks verify aspects of the VM such as the memory model
 787           and other information provided by the architecture. Verbose
 788           information will be printed at KERN_DEBUG loglevel depending
 789           on the mminit_loglevel= command-line option.
 790
 791           If unsure, say Y
 792
 793 config DEBUG_LIST
 794         bool "Debug linked list manipulation"
 795         depends on DEBUG_KERNEL
 796         help
 797           Enable this to turn on extended checks in the linked-list
 798           walking routines.
 799
 800           If unsure, say N.
 801
 802 config TEST_LIST_SORT
 803         bool "Linked list sorting test"
 804         depends on DEBUG_KERNEL
 805         help
 806           Enable this to turn on 'list_sort()' function test. This test is
 807           executed only once during system boot, so affects only boot time.
 808
 809           If unsure, say N.
 810
 811 config DEBUG_SG
 812         bool "Debug SG table operations"
 813         depends on DEBUG_KERNEL
 814         help
 815           Enable this to turn on checks on scatter-gather tables. This can
 816           help find problems with drivers that do not properly initialize
 817           their sg tables.
 818
 819           If unsure, say N.
 820
 821 config DEBUG_NOTIFIERS
 822         bool "Debug notifier call chains"
 823         depends on DEBUG_KERNEL
 824         help
 825           Enable this to turn on sanity checking for notifier call chains.
 826           This is most useful for kernel developers to make sure that
 827           modules properly unregister themselves from notifier chains.
 828           This is a relatively cheap check but if you care about maximum
 829           performance, say N.
 830
 831 config DEBUG_CREDENTIALS
 832         bool "Debug credential management"
 833         depends on DEBUG_KERNEL
 834         help
 835           Enable this to turn on some debug checking for credential
 836           management.  The additional code keeps track of the number of
 837           pointers from task_structs to any given cred struct, and checks to
 838           see that this number never exceeds the usage count of the cred
 839           struct.
 840
 841           Furthermore, if SELinux is enabled, this also checks that the
 842           security pointer in the cred struct is never seen to be invalid.
 843
 844           If unsure, say N.
 845
 846 #
 847 # Select this config option from the architecture Kconfig, if it
 848 # is preferred to always offer frame pointers as a config
 849 # option on the architecture (regardless of KERNEL_DEBUG):
 850 #
 851 config ARCH_WANT_FRAME_POINTERS
 852         bool
 853         help
 854
 855 config FRAME_POINTER
 856         bool "Compile the kernel with frame pointers"
 857         depends on DEBUG_KERNEL && \
 858                 (CRIS || M68K || FRV || UML || \
 859                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 860                 ARCH_WANT_FRAME_POINTERS
 861         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 862         help
 863           If you say Y here the resulting kernel image will be slightly
 864           larger and slower, but it gives very useful debugging information
 865           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 866
 867 config BOOT_PRINTK_DELAY
 868         bool "Delay each boot printk message by N milliseconds"
 869         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 870         help
 871           This build option allows you to read kernel boot messages
 872           by inserting a short delay after each one.  The delay is
 873           specified in milliseconds on the kernel command line,
 874           using "boot_delay=N".
 875
 876           It is likely that you would also need to use "lpj=M" to preset
 877           the "loops per jiffie" value.
 878           See a previous boot log for the "lpj" value to use for your
 879           system, and then set "lpj=M" before setting "boot_delay=N".
 880           NOTE:  Using this option may adversely affect SMP systems.
 881           I.e., processors other than the first one may not boot up.
 882           BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
 883           what it believes to be lockup conditions.
 884
 885 menu "RCU Debugging"
 886
 887 config PROVE_RCU
 888         bool "RCU debugging: prove RCU correctness"
 889         depends on PROVE_LOCKING
 890         default n
 891         help
 892          This feature enables lockdep extensions that check for correct
 893          use of RCU APIs.  This is currently under development.  Say Y
 894          if you want to debug RCU usage or help work on the PROVE_RCU
 895          feature.
 896
 897          Say N if you are unsure.
 898
 899 config PROVE_RCU_REPEATEDLY
 900         bool "RCU debugging: don't disable PROVE_RCU on first splat"
 901         depends on PROVE_RCU
 902         default n
 903         help
 904          By itself, PROVE_RCU will disable checking upon issuing the
 905          first warning (or "splat").  This feature prevents such
 906          disabling, allowing multiple RCU-lockdep warnings to be printed
 907          on a single reboot.
 908
 909          Say Y to allow multiple RCU-lockdep warnings per boot.
 910
 911          Say N if you are unsure.
 912
 913 config PROVE_RCU_DELAY
 914         bool "RCU debugging: preemptible RCU race provocation"
 915         depends on DEBUG_KERNEL && PREEMPT_RCU
 916         default n
 917         help
 918          There is a class of races that involve an unlikely preemption
 919          of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
 920          been set to INT_MIN.  This feature inserts a delay at that
 921          point to increase the probability of these races.
 922
 923          Say Y to increase probability of preemption of __rcu_read_unlock().
 924
 925          Say N if you are unsure.
 926
 927 config SPARSE_RCU_POINTER
 928         bool "RCU debugging: sparse-based checks for pointer usage"
 929         default n
 930         help
 931          This feature enables the __rcu sparse annotation for
 932          RCU-protected pointers.  This annotation will cause sparse
 933          to flag any non-RCU used of annotated pointers.  This can be
 934          helpful when debugging RCU usage.  Please note that this feature
 935          is not intended to enforce code cleanliness; it is instead merely
 936          a debugging aid.
 937
 938          Say Y to make sparse flag questionable use of RCU-protected pointers
 939
 940          Say N if you are unsure.
 941
 942 config RCU_TORTURE_TEST
 943         tristate "torture tests for RCU"
 944         depends on DEBUG_KERNEL
 945         default n
 946         help
 947           This option provides a kernel module that runs torture tests
 948           on the RCU infrastructure.  The kernel module may be built
 949           after the fact on the running kernel to be tested, if desired.
 950
 951           Say Y here if you want RCU torture tests to be built into
 952           the kernel.
 953           Say M if you want the RCU torture tests to build as a module.
 954           Say N if you are unsure.
 955
 956 config RCU_TORTURE_TEST_RUNNABLE
 957         bool "torture tests for RCU runnable by default"
 958         depends on RCU_TORTURE_TEST = y
 959         default n
 960         help
 961           This option provides a way to build the RCU torture tests
 962           directly into the kernel without them starting up at boot
 963           time.  You can use /proc/sys/kernel/rcutorture_runnable
 964           to manually override this setting.  This /proc file is
 965           available only when the RCU torture tests have been built
 966           into the kernel.
 967
 968           Say Y here if you want the RCU torture tests to start during
 969           boot (you probably don't).
 970           Say N here if you want the RCU torture tests to start only
 971           after being manually enabled via /proc.
 972
 973 config RCU_CPU_STALL_TIMEOUT
 974         int "RCU CPU stall timeout in seconds"
 975         depends on RCU_STALL_COMMON
 976         range 3 300
 977         default 21
 978         help
 979           If a given RCU grace period extends more than the specified
 980           number of seconds, a CPU stall warning is printed.  If the
 981           RCU grace period persists, additional CPU stall warnings are
 982           printed at more widely spaced intervals.
 983
 984 config RCU_CPU_STALL_VERBOSE
 985         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 986         depends on TREE_PREEMPT_RCU
 987         default y
 988         help
 989           This option causes RCU to printk detailed per-task information
 990           for any tasks that are stalling the current RCU grace period.
 991
 992           Say N if you are unsure.
 993
 994           Say Y if you want to enable such checks.
 995
 996 config RCU_CPU_STALL_INFO
 997         bool "Print additional diagnostics on RCU CPU stall"
 998         depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
 999         default n
1000         help
1001           For each stalled CPU that is aware of the current RCU grace
1002           period, print out additional per-CPU diagnostic information
1003           regarding scheduling-clock ticks, idle state, and,
1004           for RCU_FAST_NO_HZ kernels, idle-entry state.
1005
1006           Say N if you are unsure.
1007
1008           Say Y if you want to enable such diagnostics.
1009
1010 config RCU_TRACE
1011         bool "Enable tracing for RCU"
1012         depends on DEBUG_KERNEL
1013         select TRACE_CLOCK
1014         help
1015           This option provides tracing in RCU which presents stats
1016           in debugfs for debugging RCU implementation.
1017
1018           Say Y here if you want to enable RCU tracing
1019           Say N if you are unsure.
1020
1021 endmenu # "RCU Debugging"
1022
1023 config KPROBES_SANITY_TEST
1024         bool "Kprobes sanity tests"
1025         depends on DEBUG_KERNEL
1026         depends on KPROBES
1027         default n
1028         help
1029           This option provides for testing basic kprobes functionality on
1030           boot. A sample kprobe, jprobe and kretprobe are inserted and
1031           verified for functionality.
1032
1033           Say N if you are unsure.
1034
1035 config BACKTRACE_SELF_TEST
1036         tristate "Self test for the backtrace code"
1037         depends on DEBUG_KERNEL
1038         default n
1039         help
1040           This option provides a kernel module that can be used to test
1041           the kernel stack backtrace code. This option is not useful
1042           for distributions or general kernels, but only for kernel
1043           developers working on architecture code.
1044
1045           Note that if you want to also test saved backtraces, you will
1046           have to enable STACKTRACE as well.
1047
1048           Say N if you are unsure.
1049
1050 config DEBUG_BLOCK_EXT_DEVT
1051         bool "Force extended block device numbers and spread them"
1052         depends on DEBUG_KERNEL
1053         depends on BLOCK
1054         default n
1055         help
1056           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1057           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1058           YOU ARE DOING.  Distros, please enable this and fix whatever
1059           is broken.
1060
1061           Conventionally, block device numbers are allocated from
1062           predetermined contiguous area.  However, extended block area
1063           may introduce non-contiguous block device numbers.  This
1064           option forces most block device numbers to be allocated from
1065           the extended space and spreads them to discover kernel or
1066           userland code paths which assume predetermined contiguous
1067           device number allocation.
1068
1069           Note that turning on this debug option shuffles all the
1070           device numbers for all IDE and SCSI devices including libata
1071           ones, so root partition specified using device number
1072           directly (via rdev or root=MAJ:MIN) won't work anymore.
1073           Textual device names (root=/dev/sdXn) will continue to work.
1074
1075           Say N if you are unsure.
1076
1077 config DEBUG_FORCE_WEAK_PER_CPU
1078         bool "Force weak per-cpu definitions"
1079         depends on DEBUG_KERNEL
1080         help
1081           s390 and alpha require percpu variables in modules to be
1082           defined weak to work around addressing range issue which
1083           puts the following two restrictions on percpu variable
1084           definitions.
1085
1086           1. percpu symbols must be unique whether static or not
1087           2. percpu variables can't be defined inside a function
1088
1089           To ensure that generic code follows the above rules, this
1090           option forces all percpu variables to be defined as weak.
1091
1092 config DEBUG_PER_CPU_MAPS
1093         bool "Debug access to per_cpu maps"
1094         depends on DEBUG_KERNEL
1095         depends on SMP
1096         help
1097           Say Y to verify that the per_cpu map being accessed has
1098           been set up. This adds a fair amount of code to kernel memory
1099           and decreases performance.
1100
1101           Say N if unsure.
1102
1103 config LKDTM
1104         tristate "Linux Kernel Dump Test Tool Module"
1105         depends on DEBUG_FS
1106         depends on BLOCK
1107         default n
1108         help
1109         This module enables testing of the different dumping mechanisms by
1110         inducing system failures at predefined crash points.
1111         If you don't need it: say N
1112         Choose M here to compile this code as a module. The module will be
1113         called lkdtm.
1114
1115         Documentation on how to use the module can be found in
1116         Documentation/fault-injection/provoke-crashes.txt
1117
1118 config NOTIFIER_ERROR_INJECTION
1119         tristate "Notifier error injection"
1120         depends on DEBUG_KERNEL
1121         select DEBUG_FS
1122         help
1123           This option provides the ability to inject artificial errors to
1124           specified notifier chain callbacks. It is useful to test the error
1125           handling of notifier call chain failures.
1126
1127           Say N if unsure.
1128
1129 config CPU_NOTIFIER_ERROR_INJECT
1130         tristate "CPU notifier error injection module"
1131         depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1132         help
1133           This option provides a kernel module that can be used to test
1134           the error handling of the cpu notifiers by injecting artificial
1135           errors to CPU notifier chain callbacks.  It is controlled through
1136           debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1137
1138           If the notifier call chain should be failed with some events
1139           notified, write the error code to "actions/<notifier event>/error".
1140
1141           Example: Inject CPU offline error (-1 == -EPERM)
1142
1143           # cd /sys/kernel/debug/notifier-error-inject/cpu
1144           # echo -1 > actions/CPU_DOWN_PREPARE/error
1145           # echo 0 > /sys/devices/system/cpu/cpu1/online
1146           bash: echo: write error: Operation not permitted
1147
1148           To compile this code as a module, choose M here: the module will
1149           be called cpu-notifier-error-inject.
1150
1151           If unsure, say N.
1152
1153 config PM_NOTIFIER_ERROR_INJECT
1154         tristate "PM notifier error injection module"
1155         depends on PM && NOTIFIER_ERROR_INJECTION
1156         default m if PM_DEBUG
1157         help
1158           This option provides the ability to inject artificial errors to
1159           PM notifier chain callbacks.  It is controlled through debugfs
1160           interface /sys/kernel/debug/notifier-error-inject/pm
1161
1162           If the notifier call chain should be failed with some events
1163           notified, write the error code to "actions/<notifier event>/error".
1164
1165           Example: Inject PM suspend error (-12 = -ENOMEM)
1166
1167           # cd /sys/kernel/debug/notifier-error-inject/pm/
1168           # echo -12 > actions/PM_SUSPEND_PREPARE/error
1169           # echo mem > /sys/power/state
1170           bash: echo: write error: Cannot allocate memory
1171
1172           To compile this code as a module, choose M here: the module will
1173           be called pm-notifier-error-inject.
1174
1175           If unsure, say N.
1176
1177 config MEMORY_NOTIFIER_ERROR_INJECT
1178         tristate "Memory hotplug notifier error injection module"
1179         depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1180         help
1181           This option provides the ability to inject artificial errors to
1182           memory hotplug notifier chain callbacks.  It is controlled through
1183           debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
1184
1185           If the notifier call chain should be failed with some events
1186           notified, write the error code to "actions/<notifier event>/error".
1187
1188           Example: Inject memory hotplug offline error (-12 == -ENOMEM)
1189
1190           # cd /sys/kernel/debug/notifier-error-inject/memory
1191           # echo -12 > actions/MEM_GOING_OFFLINE/error
1192           # echo offline > /sys/devices/system/memory/memoryXXX/state
1193           bash: echo: write error: Cannot allocate memory
1194
1195           To compile this code as a module, choose M here: the module will
1196           be called pSeries-reconfig-notifier-error-inject.
1197
1198           If unsure, say N.
1199
1200 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1201         tristate "OF reconfig notifier error injection module"
1202         depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1203         help
1204           This option provides the ability to inject artificial errors to
1205           OF reconfig notifier chain callbacks.  It is controlled
1206           through debugfs interface under
1207           /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1208
1209           If the notifier call chain should be failed with some events
1210           notified, write the error code to "actions/<notifier event>/error".
1211
1212           To compile this code as a module, choose M here: the module will
1213           be called memory-notifier-error-inject.
1214
1215           If unsure, say N.
1216
1217 config FAULT_INJECTION
1218         bool "Fault-injection framework"
1219         depends on DEBUG_KERNEL
1220         help
1221           Provide fault-injection framework.
1222           For more details, see Documentation/fault-injection/.
1223
1224 config FAILSLAB
1225         bool "Fault-injection capability for kmalloc"
1226         depends on FAULT_INJECTION
1227         depends on SLAB || SLUB
1228         help
1229           Provide fault-injection capability for kmalloc.
1230
1231 config FAIL_PAGE_ALLOC
1232         bool "Fault-injection capabilitiy for alloc_pages()"
1233         depends on FAULT_INJECTION
1234         help
1235           Provide fault-injection capability for alloc_pages().
1236
1237 config FAIL_MAKE_REQUEST
1238         bool "Fault-injection capability for disk IO"
1239         depends on FAULT_INJECTION && BLOCK
1240         help
1241           Provide fault-injection capability for disk IO.
1242
1243 config FAIL_IO_TIMEOUT
1244         bool "Fault-injection capability for faking disk interrupts"
1245         depends on FAULT_INJECTION && BLOCK
1246         help
1247           Provide fault-injection capability on end IO handling. This
1248           will make the block layer "forget" an interrupt as configured,
1249           thus exercising the error handling.
1250
1251           Only works with drivers that use the generic timeout handling,
1252           for others it wont do anything.
1253
1254 config FAIL_MMC_REQUEST
1255         bool "Fault-injection capability for MMC IO"
1256         select DEBUG_FS
1257         depends on FAULT_INJECTION && MMC
1258         help
1259           Provide fault-injection capability for MMC IO.
1260           This will make the mmc core return data errors. This is
1261           useful to test the error handling in the mmc block device
1262           and to test how the mmc host driver handles retries from
1263           the block device.
1264
1265 config FAULT_INJECTION_DEBUG_FS
1266         bool "Debugfs entries for fault-injection capabilities"
1267         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1268         help
1269           Enable configuration of fault-injection capabilities via debugfs.
1270
1271 config FAULT_INJECTION_STACKTRACE_FILTER
1272         bool "stacktrace filter for fault-injection capabilities"
1273         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1274         depends on !X86_64
1275         select STACKTRACE
1276         select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1277         help
1278           Provide stacktrace filter for fault-injection capabilities
1279
1280 config LATENCYTOP
1281         bool "Latency measuring infrastructure"
1282         depends on HAVE_LATENCYTOP_SUPPORT
1283         depends on DEBUG_KERNEL
1284         depends on STACKTRACE_SUPPORT
1285         depends on PROC_FS
1286         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1287         select KALLSYMS
1288         select KALLSYMS_ALL
1289         select STACKTRACE
1290         select SCHEDSTATS
1291         select SCHED_DEBUG
1292         help
1293           Enable this option if you want to use the LatencyTOP tool
1294           to find out which userspace is blocking on what kernel operations.
1295
1296 source mm/Kconfig.debug
1297 source kernel/trace/Kconfig
1298
1299 config RBTREE_TEST
1300         tristate "Red-Black tree test"
1301         depends on m && DEBUG_KERNEL
1302         help
1303           A benchmark measuring the performance of the rbtree library.
1304           Also includes rbtree invariant checks.
1305
1306 config INTERVAL_TREE_TEST
1307         tristate "Interval tree test"
1308         depends on m && DEBUG_KERNEL
1309         help
1310           A benchmark measuring the performance of the interval tree library
1311
1312 config PROVIDE_OHCI1394_DMA_INIT
1313         bool "Remote debugging over FireWire early on boot"
1314         depends on PCI && X86
1315         help
1316           If you want to debug problems which hang or crash the kernel early
1317           on boot and the crashing machine has a FireWire port, you can use
1318           this feature to remotely access the memory of the crashed machine
1319           over FireWire. This employs remote DMA as part of the OHCI1394
1320           specification which is now the standard for FireWire controllers.
1321
1322           With remote DMA, you can monitor the printk buffer remotely using
1323           firescope and access all memory below 4GB using fireproxy from gdb.
1324           Even controlling a kernel debugger is possible using remote DMA.
1325
1326           Usage:
1327
1328           If ohci1394_dma=early is used as boot parameter, it will initialize
1329           all OHCI1394 controllers which are found in the PCI config space.
1330
1331           As all changes to the FireWire bus such as enabling and disabling
1332           devices cause a bus reset and thereby disable remote DMA for all
1333           devices, be sure to have the cable plugged and FireWire enabled on
1334           the debugging host before booting the debug target for debugging.
1335
1336           This code (~1k) is freed after boot. By then, the firewire stack
1337           in charge of the OHCI-1394 controllers should be used instead.
1338
1339           See Documentation/debugging-via-ohci1394.txt for more information.
1340
1341 config FIREWIRE_OHCI_REMOTE_DMA
1342         bool "Remote debugging over FireWire with firewire-ohci"
1343         depends on FIREWIRE_OHCI
1344         help
1345           This option lets you use the FireWire bus for remote debugging
1346           with help of the firewire-ohci driver. It enables unfiltered
1347           remote DMA in firewire-ohci.
1348           See Documentation/debugging-via-ohci1394.txt for more information.
1349
1350           If unsure, say N.
1351
1352 config BUILD_DOCSRC
1353         bool "Build targets in Documentation/ tree"
1354         depends on HEADERS_CHECK
1355         help
1356           This option attempts to build objects from the source files in the
1357           kernel Documentation/ tree.
1358
1359           Say N if you are unsure.
1360
1361 config DYNAMIC_DEBUG
1362         bool "Enable dynamic printk() support"
1363         default n
1364         depends on PRINTK
1365         depends on DEBUG_FS
1366         help
1367
1368           Compiles debug level messages into the kernel, which would not
1369           otherwise be available at runtime. These messages can then be
1370           enabled/disabled based on various levels of scope - per source file,
1371           function, module, format string, and line number. This mechanism
1372           implicitly compiles in all pr_debug() and dev_dbg() calls, which
1373           enlarges the kernel text size by about 2%.
1374
1375           If a source file is compiled with DEBUG flag set, any
1376           pr_debug() calls in it are enabled by default, but can be
1377           disabled at runtime as below.  Note that DEBUG flag is
1378           turned on by many CONFIG_*DEBUG* options.
1379
1380           Usage:
1381
1382           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1383           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1384           filesystem must first be mounted before making use of this feature.
1385           We refer the control file as: <debugfs>/dynamic_debug/control. This
1386           file contains a list of the debug statements that can be enabled. The
1387           format for each line of the file is:
1388
1389                 filename:lineno [module]function flags format
1390
1391           filename : source file of the debug statement
1392           lineno : line number of the debug statement
1393           module : module that contains the debug statement
1394           function : function that contains the debug statement
1395           flags : '=p' means the line is turned 'on' for printing
1396           format : the format used for the debug statement
1397
1398           From a live system:
1399
1400                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1401                 # filename:lineno [module]function flags format
1402                 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1403                 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1404                 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
1405
1406           Example usage:
1407
1408                 // enable the message at line 1603 of file svcsock.c
1409                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1410                                                 <debugfs>/dynamic_debug/control
1411
1412                 // enable all the messages in file svcsock.c
1413                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1414                                                 <debugfs>/dynamic_debug/control
1415
1416                 // enable all the messages in the NFS server module
1417                 nullarbor:~ # echo -n 'module nfsd +p' >
1418                                                 <debugfs>/dynamic_debug/control
1419
1420                 // enable all 12 messages in the function svc_process()
1421                 nullarbor:~ # echo -n 'func svc_process +p' >
1422                                                 <debugfs>/dynamic_debug/control
1423
1424                 // disable all 12 messages in the function svc_process()
1425                 nullarbor:~ # echo -n 'func svc_process -p' >
1426                                                 <debugfs>/dynamic_debug/control
1427
1428           See Documentation/dynamic-debug-howto.txt for additional information.
1429
1430 config DMA_API_DEBUG
1431         bool "Enable debugging of DMA-API usage"
1432         depends on HAVE_DMA_API_DEBUG
1433         help
1434           Enable this option to debug the use of the DMA API by device drivers.
1435           With this option you will be able to detect common bugs in device
1436           drivers like double-freeing of DMA mappings or freeing mappings that
1437           were never allocated.
1438           This option causes a performance degredation.  Use only if you want
1439           to debug device drivers. If unsure, say N.
1440
1441 config ATOMIC64_SELFTEST
1442         bool "Perform an atomic64_t self-test at boot"
1443         help
1444           Enable this option to test the atomic64_t functions at boot.
1445
1446           If unsure, say N.
1447
1448 config ASYNC_RAID6_TEST
1449         tristate "Self test for hardware accelerated raid6 recovery"
1450         depends on ASYNC_RAID6_RECOV
1451         select ASYNC_MEMCPY
1452         ---help---
1453           This is a one-shot self test that permutes through the
1454           recovery of all the possible two disk failure scenarios for a
1455           N-disk array.  Recovery is performed with the asynchronous
1456           raid6 recovery routines, and will optionally use an offload
1457           engine if one is available.
1458
1459           If unsure, say N.
1460
1461 source "samples/Kconfig"
1462
1463 source "lib/Kconfig.kgdb"
1464
1465 source "lib/Kconfig.kmemcheck"
1466
1467 config TEST_KSTRTOX
1468         tristate "Test kstrto*() family of functions at runtime"