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           If NMIs are not available on the platform, every 12 seconds the
 195           hrtimer interrupt on one cpu will be used to check for hardlockups
 196           on the next cpu.
 197
 198           The frequency of hrtimer and NMI events and the soft and hard lockup
 199           thresholds can be controlled through the sysctl watchdog_thresh.
 200
 201 config HARDLOCKUP_DETECTOR_NMI
 202         def_bool y
 203         depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
 204         depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
 205
 206 config HARDLOCKUP_DETECTOR_OTHER_CPU
 207         def_bool y
 208         depends on LOCKUP_DETECTOR && SMP
 209         depends on !HARDLOCKUP_DETECTOR_NMI && !HAVE_NMI_WATCHDOG
 210
 211 config HARDLOCKUP_DETECTOR
 212         def_bool y
 213         depends on HARDLOCKUP_DETECTOR_NMI || HARDLOCKUP_DETECTOR_OTHER_CPU
 214
 215 config BOOTPARAM_HARDLOCKUP_PANIC
 216         bool "Panic (Reboot) On Hard Lockups"
 217         depends on HARDLOCKUP_DETECTOR
 218         help
 219           Say Y here to enable the kernel to panic on "hard lockups",
 220           which are bugs that cause the kernel to loop in kernel
 221           mode with interrupts disabled for more than 10 seconds (configurable
 222           using the watchdog_thresh sysctl).
 223
 224           Say N if unsure.
 225
 226 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
 227         int
 228         depends on HARDLOCKUP_DETECTOR
 229         range 0 1
 230         default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
 231         default 1 if BOOTPARAM_HARDLOCKUP_PANIC
 232
 233 config BOOTPARAM_SOFTLOCKUP_PANIC
 234         bool "Panic (Reboot) On Soft Lockups"
 235         depends on LOCKUP_DETECTOR
 236         help
 237           Say Y here to enable the kernel to panic on "soft lockups",
 238           which are bugs that cause the kernel to loop in kernel
 239           mode for more than 20 seconds (configurable using the watchdog_thresh
 240           sysctl), without giving other tasks a chance to run.
 241
 242           The panic can be used in combination with panic_timeout,
 243           to cause the system to reboot automatically after a
 244           lockup has been detected. This feature is useful for
 245           high-availability systems that have uptime guarantees and
 246           where a lockup must be resolved ASAP.
 247
 248           Say N if unsure.
 249
 250 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 251         int
 252         depends on LOCKUP_DETECTOR
 253         range 0 1
 254         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 255         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 256
 257 config PANIC_ON_OOPS
 258         bool "Panic on Oops"
 259         help
 260           Say Y here to enable the kernel to panic when it oopses. This
 261           has the same effect as setting oops=panic on the kernel command
 262           line.
 263
 264           This feature is useful to ensure that the kernel does not do
 265           anything erroneous after an oops which could result in data
 266           corruption or other issues.
 267
 268           Say N if unsure.
 269
 270 config PANIC_ON_OOPS_VALUE
 271         int
 272         range 0 1
 273         default 0 if !PANIC_ON_OOPS
 274         default 1 if PANIC_ON_OOPS
 275
 276 config DETECT_HUNG_TASK
 277         bool "Detect Hung Tasks"
 278         depends on DEBUG_KERNEL
 279         default LOCKUP_DETECTOR
 280         help
 281           Say Y here to enable the kernel to detect "hung tasks",
 282           which are bugs that cause the task to be stuck in
 283           uninterruptible "D" state indefinitiley.
 284
 285           When a hung task is detected, the kernel will print the
 286           current stack trace (which you should report), but the
 287           task will stay in uninterruptible state. If lockdep is
 288           enabled then all held locks will also be reported. This
 289           feature has negligible overhead.
 290
 291 config DEFAULT_HUNG_TASK_TIMEOUT
 292         int "Default timeout for hung task detection (in seconds)"
 293         depends on DETECT_HUNG_TASK
 294         default 120
 295         help
 296           This option controls the default timeout (in seconds) used
 297           to determine when a task has become non-responsive and should
 298           be considered hung.
 299
 300           It can be adjusted at runtime via the kernel.hung_task_timeout_secs
 301           sysctl or by writing a value to
 302           /proc/sys/kernel/hung_task_timeout_secs.
 303
 304           A timeout of 0 disables the check.  The default is two minutes.
 305           Keeping the default should be fine in most cases.
 306
 307 config BOOTPARAM_HUNG_TASK_PANIC
 308         bool "Panic (Reboot) On Hung Tasks"
 309         depends on DETECT_HUNG_TASK
 310         help
 311           Say Y here to enable the kernel to panic on "hung tasks",
 312           which are bugs that cause the kernel to leave a task stuck
 313           in uninterruptible "D" state.
 314
 315           The panic can be used in combination with panic_timeout,
 316           to cause the system to reboot automatically after a
 317           hung task has been detected. This feature is useful for
 318           high-availability systems that have uptime guarantees and
 319           where a hung tasks must be resolved ASAP.
 320
 321           Say N if unsure.
 322
 323 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 324         int
 325         depends on DETECT_HUNG_TASK
 326         range 0 1
 327         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 328         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 329
 330 config SCHED_DEBUG
 331         bool "Collect scheduler debugging info"
 332         depends on DEBUG_KERNEL && PROC_FS
 333         default y
 334         help
 335           If you say Y here, the /proc/sched_debug file will be provided
 336           that can help debug the scheduler. The runtime overhead of this
 337           option is minimal.
 338
 339 config SCHEDSTATS
 340         bool "Collect scheduler statistics"
 341         depends on DEBUG_KERNEL && PROC_FS
 342         help
 343           If you say Y here, additional code will be inserted into the
 344           scheduler and related routines to collect statistics about
 345           scheduler behavior and provide them in /proc/schedstat.  These
 346           stats may be useful for both tuning and debugging the scheduler
 347           If you aren't debugging the scheduler or trying to tune a specific
 348           application, you can say N to avoid the very slight overhead
 349           this adds.
 350
 351 config TIMER_STATS
 352         bool "Collect kernel timers statistics"
 353         depends on DEBUG_KERNEL && PROC_FS
 354         help
 355           If you say Y here, additional code will be inserted into the
 356           timer routines to collect statistics about kernel timers being
 357           reprogrammed. The statistics can be read from /proc/timer_stats.
 358           The statistics collection is started by writing 1 to /proc/timer_stats,
 359           writing 0 stops it. This feature is useful to collect information
 360           about timer usage patterns in kernel and userspace. This feature
 361           is lightweight if enabled in the kernel config but not activated
 362           (it defaults to deactivated on bootup and will only be activated
 363           if some application like powertop activates it explicitly).
 364
 365 config DEBUG_OBJECTS
 366         bool "Debug object operations"
 367         depends on DEBUG_KERNEL
 368         help
 369           If you say Y here, additional code will be inserted into the
 370           kernel to track the life time of various objects and validate
 371           the operations on those objects.
 372
 373 config DEBUG_OBJECTS_SELFTEST
 374         bool "Debug objects selftest"
 375         depends on DEBUG_OBJECTS
 376         help
 377           This enables the selftest of the object debug code.
 378
 379 config DEBUG_OBJECTS_FREE
 380         bool "Debug objects in freed memory"
 381         depends on DEBUG_OBJECTS
 382         help
 383           This enables checks whether a k/v free operation frees an area
 384           which contains an object which has not been deactivated
 385           properly. This can make kmalloc/kfree-intensive workloads
 386           much slower.
 387
 388 config DEBUG_OBJECTS_TIMERS
 389         bool "Debug timer objects"
 390         depends on DEBUG_OBJECTS
 391         help
 392           If you say Y here, additional code will be inserted into the
 393           timer routines to track the life time of timer objects and
 394           validate the timer operations.
 395
 396 config DEBUG_OBJECTS_WORK
 397         bool "Debug work objects"
 398         depends on DEBUG_OBJECTS
 399         help
 400           If you say Y here, additional code will be inserted into the
 401           work queue routines to track the life time of work objects and
 402           validate the work operations.
 403
 404 config DEBUG_OBJECTS_RCU_HEAD
 405         bool "Debug RCU callbacks objects"
 406         depends on DEBUG_OBJECTS
 407         help
 408           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 409
 410 config DEBUG_OBJECTS_PERCPU_COUNTER
 411         bool "Debug percpu counter objects"
 412         depends on DEBUG_OBJECTS
 413         help
 414           If you say Y here, additional code will be inserted into the
 415           percpu counter routines to track the life time of percpu counter
 416           objects and validate the percpu counter operations.
 417
 418 config DEBUG_OBJECTS_ENABLE_DEFAULT
 419         int "debug_objects bootup default value (0-1)"
 420         range 0 1
 421         default "1"
 422         depends on DEBUG_OBJECTS
 423         help
 424           Debug objects boot parameter default value
 425
 426 config DEBUG_SLAB
 427         bool "Debug slab memory allocations"
 428         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 429         help
 430           Say Y here to have the kernel do limited verification on memory
 431           allocation as well as poisoning memory on free to catch use of freed
 432           memory. This can make kmalloc/kfree-intensive workloads much slower.
 433
 434 config DEBUG_SLAB_LEAK
 435         bool "Memory leak debugging"
 436         depends on DEBUG_SLAB
 437
 438 config SLUB_DEBUG_ON
 439         bool "SLUB debugging on by default"
 440         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 441         default n
 442         help
 443           Boot with debugging on by default. SLUB boots by default with
 444           the runtime debug capabilities switched off. Enabling this is
 445           equivalent to specifying the "slub_debug" parameter on boot.
 446           There is no support for more fine grained debug control like
 447           possible with slub_debug=xxx. SLUB debugging may be switched
 448           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 449           "slub_debug=-".
 450
 451 config SLUB_STATS
 452         default n
 453         bool "Enable SLUB performance statistics"
 454         depends on SLUB && SYSFS
 455         help
 456           SLUB statistics are useful to debug SLUBs allocation behavior in
 457           order find ways to optimize the allocator. This should never be
 458           enabled for production use since keeping statistics slows down
 459           the allocator by a few percentage points. The slabinfo command
 460           supports the determination of the most active slabs to figure
 461           out which slabs are relevant to a particular load.
 462           Try running: slabinfo -DA
 463
 464 config HAVE_DEBUG_KMEMLEAK
 465         bool
 466
 467 config DEBUG_KMEMLEAK
 468         bool "Kernel memory leak detector"
 469         depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
 470         select DEBUG_FS
 471         select STACKTRACE if STACKTRACE_SUPPORT
 472         select KALLSYMS
 473         select CRC32
 474         help
 475           Say Y here if you want to enable the memory leak
 476           detector. The memory allocation/freeing is traced in a way
 477           similar to the Boehm's conservative garbage collector, the
 478           difference being that the orphan objects are not freed but
 479           only shown in /sys/kernel/debug/kmemleak. Enabling this
 480           feature will introduce an overhead to memory
 481           allocations. See Documentation/kmemleak.txt for more
 482           details.
 483
 484           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 485           of finding leaks due to the slab objects poisoning.
 486
 487           In order to access the kmemleak file, debugfs needs to be
 488           mounted (usually at /sys/kernel/debug).
 489
 490 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 491         int "Maximum kmemleak early log entries"
 492         depends on DEBUG_KMEMLEAK
 493         range 200 40000
 494         default 400
 495         help
 496           Kmemleak must track all the memory allocations to avoid
 497           reporting false positives. Since memory may be allocated or
 498           freed before kmemleak is initialised, an early log buffer is
 499           used to store these actions. If kmemleak reports "early log
 500           buffer exceeded", please increase this value.
 501
 502 config DEBUG_KMEMLEAK_TEST
 503         tristate "Simple test for the kernel memory leak detector"
 504         depends on DEBUG_KMEMLEAK && m
 505         help
 506           This option enables a module that explicitly leaks memory.
 507
 508           If unsure, say N.
 509
 510 config DEBUG_KMEMLEAK_DEFAULT_OFF
 511         bool "Default kmemleak to off"
 512         depends on DEBUG_KMEMLEAK
 513         help
 514           Say Y here to disable kmemleak by default. It can then be enabled
 515           on the command line via kmemleak=on.
 516
 517 config DEBUG_PREEMPT
 518         bool "Debug preemptible kernel"
 519         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 520         default y
 521         help
 522           If you say Y here then the kernel will use a debug variant of the
 523           commonly used smp_processor_id() function and will print warnings
 524           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 525           will detect preemption count underflows.
 526
 527 config DEBUG_RT_MUTEXES
 528         bool "RT Mutex debugging, deadlock detection"
 529         depends on DEBUG_KERNEL && RT_MUTEXES
 530         help
 531          This allows rt mutex semantics violations and rt mutex related
 532          deadlocks (lockups) to be detected and reported automatically.
 533
 534 config DEBUG_PI_LIST
 535         bool
 536         default y
 537         depends on DEBUG_RT_MUTEXES
 538
 539 config RT_MUTEX_TESTER
 540         bool "Built-in scriptable tester for rt-mutexes"
 541         depends on DEBUG_KERNEL && RT_MUTEXES
 542         help
 543           This option enables a rt-mutex tester.
 544
 545 config DEBUG_SPINLOCK
 546         bool "Spinlock and rw-lock debugging: basic checks"
 547         depends on DEBUG_KERNEL
 548         select UNINLINE_SPIN_UNLOCK
 549         help
 550           Say Y here and build SMP to catch missing spinlock initialization
 551           and certain other kinds of spinlock errors commonly made.  This is
 552           best used in conjunction with the NMI watchdog so that spinlock
 553           deadlocks are also debuggable.
 554
 555 config DEBUG_MUTEXES
 556         bool "Mutex debugging: basic checks"
 557         depends on DEBUG_KERNEL
 558         help
 559          This feature allows mutex semantics violations to be detected and
 560          reported.
 561
 562 config DEBUG_LOCK_ALLOC
 563         bool "Lock debugging: detect incorrect freeing of live locks"
 564         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 565         select DEBUG_SPINLOCK
 566         select DEBUG_MUTEXES
 567         select LOCKDEP
 568         help
 569          This feature will check whether any held lock (spinlock, rwlock,
 570          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 571          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 572          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 573          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 574          held during task exit.
 575
 576 config PROVE_LOCKING
 577         bool "Lock debugging: prove locking correctness"
 578         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 579         select LOCKDEP
 580         select DEBUG_SPINLOCK
 581         select DEBUG_MUTEXES
 582         select DEBUG_LOCK_ALLOC
 583         select TRACE_IRQFLAGS
 584         default n
 585         help
 586          This feature enables the kernel to prove that all locking
 587          that occurs in the kernel runtime is mathematically
 588          correct: that under no circumstance could an arbitrary (and
 589          not yet triggered) combination of observed locking
 590          sequences (on an arbitrary number of CPUs, running an
 591          arbitrary number of tasks and interrupt contexts) cause a
 592          deadlock.
 593
 594          In short, this feature enables the kernel to report locking
 595          related deadlocks before they actually occur.
 596
 597          The proof does not depend on how hard and complex a
 598          deadlock scenario would be to trigger: how many
 599          participant CPUs, tasks and irq-contexts would be needed
 600          for it to trigger. The proof also does not depend on
 601          timing: if a race and a resulting deadlock is possible
 602          theoretically (no matter how unlikely the race scenario
 603          is), it will be proven so and will immediately be
 604          reported by the kernel (once the event is observed that
 605          makes the deadlock theoretically possible).
 606
 607          If a deadlock is impossible (i.e. the locking rules, as
 608          observed by the kernel, are mathematically correct), the
 609          kernel reports nothing.
 610
 611          NOTE: this feature can also be enabled for rwlocks, mutexes
 612          and rwsems - in which case all dependencies between these
 613          different locking variants are observed and mapped too, and
 614          the proof of observed correctness is also maintained for an
 615          arbitrary combination of these separate locking variants.
 616
 617          For more details, see Documentation/lockdep-design.txt.
 618
 619 config LOCKDEP
 620         bool
 621         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 622         select STACKTRACE
 623         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 624         select KALLSYMS
 625         select KALLSYMS_ALL
 626
 627 config LOCK_STAT
 628         bool "Lock usage statistics"
 629         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 630         select LOCKDEP
 631         select DEBUG_SPINLOCK
 632         select DEBUG_MUTEXES
 633         select DEBUG_LOCK_ALLOC
 634         default n
 635         help
 636          This feature enables tracking lock contention points
 637
 638          For more details, see Documentation/lockstat.txt
 639
 640          This also enables lock events required by "perf lock",
 641          subcommand of perf.
 642          If you want to use "perf lock", you also need to turn on
 643          CONFIG_EVENT_TRACING.
 644
 645          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 646          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 647
 648 config DEBUG_LOCKDEP
 649         bool "Lock dependency engine debugging"
 650         depends on DEBUG_KERNEL && LOCKDEP
 651         help
 652           If you say Y here, the lock dependency engine will do
 653           additional runtime checks to debug itself, at the price
 654           of more runtime overhead.
 655
 656 config TRACE_IRQFLAGS
 657         bool
 658         help
 659           Enables hooks to interrupt enabling and disabling for
 660           either tracing or lock debugging.
 661
 662 config DEBUG_ATOMIC_SLEEP
 663         bool "Sleep inside atomic section checking"
 664         select PREEMPT_COUNT
 665         depends on DEBUG_KERNEL
 666         help
 667           If you say Y here, various routines which may sleep will become very
 668           noisy if they are called inside atomic sections: when a spinlock is
 669           held, inside an rcu read side critical section, inside preempt disabled
 670           sections, inside an interrupt, etc...
 671
 672 config DEBUG_LOCKING_API_SELFTESTS
 673         bool "Locking API boot-time self-tests"
 674         depends on DEBUG_KERNEL
 675         help
 676           Say Y here if you want the kernel to run a short self-test during
 677           bootup. The self-test checks whether common types of locking bugs
 678           are detected by debugging mechanisms or not. (if you disable
 679           lock debugging then those bugs wont be detected of course.)
 680           The following locking APIs are covered: spinlocks, rwlocks,
 681           mutexes and rwsems.
 682
 683 config STACKTRACE
 684         bool "Stacktrace"
 685         depends on STACKTRACE_SUPPORT
 686         default y
 687
 688 config DEBUG_STACK_USAGE
 689         bool "Stack utilization instrumentation"
 690         depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
 691         help
 692           Enables the display of the minimum amount of free stack which each
 693           task has ever had available in the sysrq-T and sysrq-P debug output.
 694
 695           This option will slow down process creation somewhat.
 696
 697 config DEBUG_KOBJECT
 698         bool "kobject debugging"
 699         depends on DEBUG_KERNEL
 700         help
 701           If you say Y here, some extra kobject debugging messages will be sent
 702           to the syslog.
 703
 704 config DEBUG_HIGHMEM
 705         bool "Highmem debugging"
 706         depends on DEBUG_KERNEL && HIGHMEM
 707         help
 708           This options enables addition error checking for high memory systems.
 709           Disable for production systems.
 710
 711 config HAVE_DEBUG_BUGVERBOSE
 712         bool
 713
 714 config DEBUG_BUGVERBOSE
 715         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
 716         depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
 717         default y
 718         help
 719           Say Y here to make BUG() panics output the file name and line number
 720           of the BUG call as well as the EIP and oops trace.  This aids
 721           debugging but costs about 70-100K of memory.
 722
 723 config DEBUG_INFO
 724         bool "Compile the kernel with debug info"
 725         depends on DEBUG_KERNEL
 726         help
 727           If you say Y here the resulting kernel image will include
 728           debugging info resulting in a larger kernel image.
 729           This adds debug symbols to the kernel and modules (gcc -g), and
 730           is needed if you intend to use kernel crashdump or binary object
 731           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 732           Say Y here only if you plan to debug the kernel.
 733
 734           If unsure, say N.
 735
 736 config DEBUG_INFO_REDUCED
 737         bool "Reduce debugging information"
 738         depends on DEBUG_INFO
 739         help
 740           If you say Y here gcc is instructed to generate less debugging
 741           information for structure types. This means that tools that
 742           need full debugging information (like kgdb or systemtap) won't
 743           be happy. But if you merely need debugging information to
 744           resolve line numbers there is no loss. Advantage is that
 745           build directory object sizes shrink dramatically over a full
 746           DEBUG_INFO build and compile times are reduced too.
 747           Only works with newer gcc versions.
 748
 749 config DEBUG_VM
 750         bool "Debug VM"
 751         depends on DEBUG_KERNEL
 752         help
 753           Enable this to turn on extended checks in the virtual-memory system
 754           that may impact performance.
 755
 756           If unsure, say N.
 757
 758 config DEBUG_VM_RB
 759         bool "Debug VM red-black trees"
 760         depends on DEBUG_VM
 761         help
 762           Enable this to turn on more extended checks in the virtual-memory
 763           system that may impact performance.
 764
 765           If unsure, say N.
 766
 767 config DEBUG_VIRTUAL
 768         bool "Debug VM translations"
 769         depends on DEBUG_KERNEL && X86
 770         help
 771           Enable some costly sanity checks in virtual to page code. This can
 772           catch mistakes with virt_to_page() and friends.
 773
 774           If unsure, say N.
 775
 776 config DEBUG_NOMMU_REGIONS
 777         bool "Debug the global anon/private NOMMU mapping region tree"
 778         depends on DEBUG_KERNEL && !MMU
 779         help
 780           This option causes the global tree of anonymous and private mapping
 781           regions to be regularly checked for invalid topology.
 782
 783 config DEBUG_WRITECOUNT
 784         bool "Debug filesystem writers count"
 785         depends on DEBUG_KERNEL
 786         help
 787           Enable this to catch wrong use of the writers count in struct
 788           vfsmount.  This will increase the size of each file struct by
 789           32 bits.
 790
 791           If unsure, say N.
 792
 793 config DEBUG_MEMORY_INIT
 794         bool "Debug memory initialisation" if EXPERT
 795         default !EXPERT
 796         help
 797           Enable this for additional checks during memory initialisation.
 798           The sanity checks verify aspects of the VM such as the memory model
 799           and other information provided by the architecture. Verbose
 800           information will be printed at KERN_DEBUG loglevel depending
 801           on the mminit_loglevel= command-line option.
 802
 803           If unsure, say Y
 804
 805 config DEBUG_LIST
 806         bool "Debug linked list manipulation"
 807         depends on DEBUG_KERNEL
 808         help
 809           Enable this to turn on extended checks in the linked-list
 810           walking routines.
 811
 812           If unsure, say N.
 813
 814 config TEST_LIST_SORT
 815         bool "Linked list sorting test"
 816         depends on DEBUG_KERNEL
 817         help
 818           Enable this to turn on 'list_sort()' function test. This test is
 819           executed only once during system boot, so affects only boot time.
 820
 821           If unsure, say N.
 822
 823 config DEBUG_SG
 824         bool "Debug SG table operations"
 825         depends on DEBUG_KERNEL
 826         help
 827           Enable this to turn on checks on scatter-gather tables. This can
 828           help find problems with drivers that do not properly initialize
 829           their sg tables.
 830
 831           If unsure, say N.
 832
 833 config DEBUG_NOTIFIERS
 834         bool "Debug notifier call chains"
 835         depends on DEBUG_KERNEL
 836         help
 837           Enable this to turn on sanity checking for notifier call chains.
 838           This is most useful for kernel developers to make sure that
 839           modules properly unregister themselves from notifier chains.
 840           This is a relatively cheap check but if you care about maximum
 841           performance, say N.
 842
 843 config DEBUG_CREDENTIALS
 844         bool "Debug credential management"
 845         depends on DEBUG_KERNEL
 846         help
 847           Enable this to turn on some debug checking for credential
 848           management.  The additional code keeps track of the number of
 849           pointers from task_structs to any given cred struct, and checks to
 850           see that this number never exceeds the usage count of the cred
 851           struct.
 852
 853           Furthermore, if SELinux is enabled, this also checks that the
 854           security pointer in the cred struct is never seen to be invalid.
 855
 856           If unsure, say N.
 857
 858 #
 859 # Select this config option from the architecture Kconfig, if it
 860 # is preferred to always offer frame pointers as a config
 861 # option on the architecture (regardless of KERNEL_DEBUG):
 862 #
 863 config ARCH_WANT_FRAME_POINTERS
 864         bool
 865         help
 866
 867 config FRAME_POINTER
 868         bool "Compile the kernel with frame pointers"
 869         depends on DEBUG_KERNEL && \
 870                 (CRIS || M68K || FRV || UML || \
 871                  AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
 872                 ARCH_WANT_FRAME_POINTERS
 873         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 874         help
 875           If you say Y here the resulting kernel image will be slightly
 876           larger and slower, but it gives very useful debugging information
 877           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 878
 879 config BOOT_PRINTK_DELAY
 880         bool "Delay each boot printk message by N milliseconds"
 881         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 882         help
 883           This build option allows you to read kernel boot messages
 884           by inserting a short delay after each one.  The delay is
 885           specified in milliseconds on the kernel command line,
 886           using "boot_delay=N".
 887
 888           It is likely that you would also need to use "lpj=M" to preset
 889           the "loops per jiffie" value.
 890           See a previous boot log for the "lpj" value to use for your
 891           system, and then set "lpj=M" before setting "boot_delay=N".
 892           NOTE:  Using this option may adversely affect SMP systems.
 893           I.e., processors other than the first one may not boot up.
 894           BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
 895           what it believes to be lockup conditions.
 896
 897 menu "RCU Debugging"
 898
 899 config PROVE_RCU
 900         bool "RCU debugging: prove RCU correctness"
 901         depends on PROVE_LOCKING
 902         default n
 903         help
 904          This feature enables lockdep extensions that check for correct
 905          use of RCU APIs.  This is currently under development.  Say Y
 906          if you want to debug RCU usage or help work on the PROVE_RCU
 907          feature.
 908
 909          Say N if you are unsure.
 910
 911 config PROVE_RCU_REPEATEDLY
 912         bool "RCU debugging: don't disable PROVE_RCU on first splat"
 913         depends on PROVE_RCU
 914         default n
 915         help
 916          By itself, PROVE_RCU will disable checking upon issuing the
 917          first warning (or "splat").  This feature prevents such
 918          disabling, allowing multiple RCU-lockdep warnings to be printed
 919          on a single reboot.
 920
 921          Say Y to allow multiple RCU-lockdep warnings per boot.
 922
 923          Say N if you are unsure.
 924
 925 config PROVE_RCU_DELAY
 926         bool "RCU debugging: preemptible RCU race provocation"
 927         depends on DEBUG_KERNEL && PREEMPT_RCU
 928         default n
 929         help
 930          There is a class of races that involve an unlikely preemption
 931          of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
 932          been set to INT_MIN.  This feature inserts a delay at that
 933          point to increase the probability of these races.
 934
 935          Say Y to increase probability of preemption of __rcu_read_unlock().
 936
 937          Say N if you are unsure.
 938
 939 config SPARSE_RCU_POINTER
 940         bool "RCU debugging: sparse-based checks for pointer usage"
 941         default n
 942         help
 943          This feature enables the __rcu sparse annotation for
 944          RCU-protected pointers.  This annotation will cause sparse
 945          to flag any non-RCU used of annotated pointers.  This can be
 946          helpful when debugging RCU usage.  Please note that this feature
 947          is not intended to enforce code cleanliness; it is instead merely
 948          a debugging aid.
 949
 950          Say Y to make sparse flag questionable use of RCU-protected pointers
 951
 952          Say N if you are unsure.
 953
 954 config RCU_TORTURE_TEST
 955         tristate "torture tests for RCU"
 956         depends on DEBUG_KERNEL
 957         default n
 958         help
 959           This option provides a kernel module that runs torture tests
 960           on the RCU infrastructure.  The kernel module may be built
 961           after the fact on the running kernel to be tested, if desired.
 962
 963           Say Y here if you want RCU torture tests to be built into
 964           the kernel.
 965           Say M if you want the RCU torture tests to build as a module.
 966           Say N if you are unsure.
 967
 968 config RCU_TORTURE_TEST_RUNNABLE
 969         bool "torture tests for RCU runnable by default"
 970         depends on RCU_TORTURE_TEST = y
 971         default n
 972         help
 973           This option provides a way to build the RCU torture tests
 974           directly into the kernel without them starting up at boot
 975           time.  You can use /proc/sys/kernel/rcutorture_runnable
 976           to manually override this setting.  This /proc file is
 977           available only when the RCU torture tests have been built
 978           into the kernel.
 979
 980           Say Y here if you want the RCU torture tests to start during
 981           boot (you probably don't).
 982           Say N here if you want the RCU torture tests to start only
 983           after being manually enabled via /proc.
 984
 985 config RCU_CPU_STALL_TIMEOUT
 986         int "RCU CPU stall timeout in seconds"
 987         depends on RCU_STALL_COMMON
 988         range 3 300
 989         default 21
 990         help
 991           If a given RCU grace period extends more than the specified
 992           number of seconds, a CPU stall warning is printed.  If the
 993           RCU grace period persists, additional CPU stall warnings are
 994           printed at more widely spaced intervals.
 995
 996 config RCU_CPU_STALL_VERBOSE
 997         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 998         depends on TREE_PREEMPT_RCU
 999         default y
1000         help
1001           This option causes RCU to printk detailed per-task information
1002           for any tasks that are stalling the current RCU grace period.
1003
1004           Say N if you are unsure.
1005
1006           Say Y if you want to enable such checks.
1007
1008 config RCU_CPU_STALL_INFO
1009         bool "Print additional diagnostics on RCU CPU stall"
1010         depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1011         default n
1012         help
1013           For each stalled CPU that is aware of the current RCU grace
1014           period, print out additional per-CPU diagnostic information
1015           regarding scheduling-clock ticks, idle state, and,
1016           for RCU_FAST_NO_HZ kernels, idle-entry state.
1017
1018           Say N if you are unsure.
1019
1020           Say Y if you want to enable such diagnostics.
1021
1022 config RCU_TRACE
1023         bool "Enable tracing for RCU"
1024         depends on DEBUG_KERNEL
1025         select TRACE_CLOCK
1026         help
1027           This option provides tracing in RCU which presents stats
1028           in debugfs for debugging RCU implementation.
1029
1030           Say Y here if you want to enable RCU tracing
1031           Say N if you are unsure.
1032
1033 endmenu # "RCU Debugging"
1034
1035 config KPROBES_SANITY_TEST
1036         bool "Kprobes sanity tests"
1037         depends on DEBUG_KERNEL
1038         depends on KPROBES
1039         default n
1040         help
1041           This option provides for testing basic kprobes functionality on
1042           boot. A sample kprobe, jprobe and kretprobe are inserted and
1043           verified for functionality.
1044
1045           Say N if you are unsure.
1046
1047 config BACKTRACE_SELF_TEST
1048         tristate "Self test for the backtrace code"
1049         depends on DEBUG_KERNEL
1050         default n
1051         help
1052           This option provides a kernel module that can be used to test
1053           the kernel stack backtrace code. This option is not useful
1054           for distributions or general kernels, but only for kernel
1055           developers working on architecture code.
1056
1057           Note that if you want to also test saved backtraces, you will
1058           have to enable STACKTRACE as well.
1059
1060           Say N if you are unsure.
1061
1062 config DEBUG_BLOCK_EXT_DEVT
1063         bool "Force extended block device numbers and spread them"
1064         depends on DEBUG_KERNEL
1065         depends on BLOCK
1066         default n
1067         help
1068           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1069           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1070           YOU ARE DOING.  Distros, please enable this and fix whatever
1071           is broken.
1072
1073           Conventionally, block device numbers are allocated from
1074           predetermined contiguous area.  However, extended block area
1075           may introduce non-contiguous block device numbers.  This
1076           option forces most block device numbers to be allocated from
1077           the extended space and spreads them to discover kernel or
1078           userland code paths which assume predetermined contiguous
1079           device number allocation.
1080
1081           Note that turning on this debug option shuffles all the
1082           device numbers for all IDE and SCSI devices including libata
1083           ones, so root partition specified using device number
1084           directly (via rdev or root=MAJ:MIN) won't work anymore.
1085           Textual device names (root=/dev/sdXn) will continue to work.
1086
1087           Say N if you are unsure.
1088
1089 config DEBUG_FORCE_WEAK_PER_CPU
1090         bool "Force weak per-cpu definitions"
1091         depends on DEBUG_KERNEL
1092         help
1093           s390 and alpha require percpu variables in modules to be
1094           defined weak to work around addressing range issue which
1095           puts the following two restrictions on percpu variable
1096           definitions.
1097
1098           1. percpu symbols must be unique whether static or not
1099           2. percpu variables can't be defined inside a function
1100
1101           To ensure that generic code follows the above rules, this
1102           option forces all percpu variables to be defined as weak.
1103
1104 config DEBUG_PER_CPU_MAPS
1105         bool "Debug access to per_cpu maps"
1106         depends on DEBUG_KERNEL
1107         depends on SMP
1108         help
1109           Say Y to verify that the per_cpu map being accessed has
1110           been set up. This adds a fair amount of code to kernel memory
1111           and decreases performance.
1112
1113           Say N if unsure.
1114
1115 config LKDTM
1116         tristate "Linux Kernel Dump Test Tool Module"
1117         depends on DEBUG_FS
1118         depends on BLOCK
1119         default n
1120         help
1121         This module enables testing of the different dumping mechanisms by
1122         inducing system failures at predefined crash points.
1123         If you don't need it: say N
1124         Choose M here to compile this code as a module. The module will be
1125         called lkdtm.
1126
1127         Documentation on how to use the module can be found in
1128         Documentation/fault-injection/provoke-crashes.txt
1129
1130 config NOTIFIER_ERROR_INJECTION
1131         tristate "Notifier error injection"
1132         depends on DEBUG_KERNEL
1133         select DEBUG_FS
1134         help
1135           This option provides the ability to inject artificial errors to
1136           specified notifier chain callbacks. It is useful to test the error
1137           handling of notifier call chain failures.
1138
1139           Say N if unsure.
1140
1141 config CPU_NOTIFIER_ERROR_INJECT
1142         tristate "CPU notifier error injection module"
1143         depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1144         help
1145           This option provides a kernel module that can be used to test
1146           the error handling of the cpu notifiers by injecting artificial
1147           errors to CPU notifier chain callbacks.  It is controlled through
1148           debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1149
1150           If the notifier call chain should be failed with some events
1151           notified, write the error code to "actions/<notifier event>/error".
1152
1153           Example: Inject CPU offline error (-1 == -EPERM)
1154
1155           # cd /sys/kernel/debug/notifier-error-inject/cpu
1156           # echo -1 > actions/CPU_DOWN_PREPARE/error
1157           # echo 0 > /sys/devices/system/cpu/cpu1/online
1158           bash: echo: write error: Operation not permitted
1159
1160           To compile this code as a module, choose M here: the module will
1161           be called cpu-notifier-error-inject.
1162
1163           If unsure, say N.
1164
1165 config PM_NOTIFIER_ERROR_INJECT
1166         tristate "PM notifier error injection module"
1167         depends on PM && NOTIFIER_ERROR_INJECTION
1168         default m if PM_DEBUG
1169         help
1170           This option provides the ability to inject artificial errors to
1171           PM notifier chain callbacks.  It is controlled through debugfs
1172           interface /sys/kernel/debug/notifier-error-inject/pm
1173
1174           If the notifier call chain should be failed with some events
1175           notified, write the error code to "actions/<notifier event>/error".
1176
1177           Example: Inject PM suspend error (-12 = -ENOMEM)
1178
1179           # cd /sys/kernel/debug/notifier-error-inject/pm/
1180           # echo -12 > actions/PM_SUSPEND_PREPARE/error
1181           # echo mem > /sys/power/state
1182           bash: echo: write error: Cannot allocate memory
1183
1184           To compile this code as a module, choose M here: the module will
1185           be called pm-notifier-error-inject.
1186
1187           If unsure, say N.
1188
1189 config MEMORY_NOTIFIER_ERROR_INJECT
1190         tristate "Memory hotplug notifier error injection module"
1191         depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1192         help
1193           This option provides the ability to inject artificial errors to
1194           memory hotplug notifier chain callbacks.  It is controlled through
1195           debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
1196
1197           If the notifier call chain should be failed with some events
1198           notified, write the error code to "actions/<notifier event>/error".
1199
1200           Example: Inject memory hotplug offline error (-12 == -ENOMEM)
1201
1202           # cd /sys/kernel/debug/notifier-error-inject/memory
1203           # echo -12 > actions/MEM_GOING_OFFLINE/error
1204           # echo offline > /sys/devices/system/memory/memoryXXX/state
1205           bash: echo: write error: Cannot allocate memory
1206
1207           To compile this code as a module, choose M here: the module will
1208           be called memory-notifier-error-inject.
1209
1210           If unsure, say N.
1211
1212 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1213         tristate "OF reconfig notifier error injection module"
1214         depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1215         help
1216           This option provides the ability to inject artificial errors to
1217           OF reconfig notifier chain callbacks.  It is controlled
1218           through debugfs interface under
1219           /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1220
1221           If the notifier call chain should be failed with some events
1222           notified, write the error code to "actions/<notifier event>/error".
1223
1224           To compile this code as a module, choose M here: the module will
1225           be called of-reconfig-notifier-error-inject.
1226
1227           If unsure, say N.
1228
1229 config FAULT_INJECTION
1230         bool "Fault-injection framework"
1231         depends on DEBUG_KERNEL
1232         help
1233           Provide fault-injection framework.
1234           For more details, see Documentation/fault-injection/.
1235
1236 config FAILSLAB
1237         bool "Fault-injection capability for kmalloc"
1238         depends on FAULT_INJECTION
1239         depends on SLAB || SLUB
1240         help
1241           Provide fault-injection capability for kmalloc.
1242
1243 config FAIL_PAGE_ALLOC
1244         bool "Fault-injection capabilitiy for alloc_pages()"
1245         depends on FAULT_INJECTION
1246         help
1247           Provide fault-injection capability for alloc_pages().
1248
1249 config FAIL_MAKE_REQUEST
1250         bool "Fault-injection capability for disk IO"
1251         depends on FAULT_INJECTION && BLOCK
1252         help
1253           Provide fault-injection capability for disk IO.
1254
1255 config FAIL_IO_TIMEOUT
1256         bool "Fault-injection capability for faking disk interrupts"
1257         depends on FAULT_INJECTION && BLOCK
1258         help
1259           Provide fault-injection capability on end IO handling. This
1260           will make the block layer "forget" an interrupt as configured,
1261           thus exercising the error handling.
1262
1263           Only works with drivers that use the generic timeout handling,
1264           for others it wont do anything.
1265
1266 config FAIL_MMC_REQUEST
1267         bool "Fault-injection capability for MMC IO"
1268         select DEBUG_FS
1269         depends on FAULT_INJECTION && MMC
1270         help
1271           Provide fault-injection capability for MMC IO.
1272           This will make the mmc core return data errors. This is
1273           useful to test the error handling in the mmc block device
1274           and to test how the mmc host driver handles retries from
1275           the block device.
1276
1277 config FAULT_INJECTION_DEBUG_FS
1278         bool "Debugfs entries for fault-injection capabilities"
1279         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1280         help
1281           Enable configuration of fault-injection capabilities via debugfs.
1282
1283 config FAULT_INJECTION_STACKTRACE_FILTER
1284         bool "stacktrace filter for fault-injection capabilities"
1285         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1286         depends on !X86_64
1287         select STACKTRACE
1288         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1289         help
1290           Provide stacktrace filter for fault-injection capabilities
1291
1292 config LATENCYTOP
1293         bool "Latency measuring infrastructure"
1294         depends on HAVE_LATENCYTOP_SUPPORT
1295         depends on DEBUG_KERNEL
1296         depends on STACKTRACE_SUPPORT
1297         depends on PROC_FS
1298         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1299         select KALLSYMS
1300         select KALLSYMS_ALL
1301         select STACKTRACE
1302         select SCHEDSTATS
1303         select SCHED_DEBUG
1304         help
1305           Enable this option if you want to use the LatencyTOP tool
1306           to find out which userspace is blocking on what kernel operations.
1307
1308 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1309         bool
1310
1311 config DEBUG_STRICT_USER_COPY_CHECKS
1312         bool "Strict user copy size checks"
1313         depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1314         depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1315         help
1316           Enabling this option turns a certain set of sanity checks for user
1317           copy operations into compile time failures.
1318
1319           The copy_from_user() etc checks are there to help test if there
1320           are sufficient security checks on the length argument of
1321           the copy operation, by having gcc prove that the argument is
1322           within bounds.
1323
1324           If unsure, say N.
1325
1326 source mm/Kconfig.debug
1327 source kernel/trace/Kconfig
1328
1329 config RBTREE_TEST
1330         tristate "Red-Black tree test"
1331         depends on m && DEBUG_KERNEL
1332         help
1333           A benchmark measuring the performance of the rbtree library.
1334           Also includes rbtree invariant checks.
1335
1336 config INTERVAL_TREE_TEST
1337         tristate "Interval tree test"
1338         depends on m && DEBUG_KERNEL
1339         help
1340           A benchmark measuring the performance of the interval tree library
1341
1342 config PROVIDE_OHCI1394_DMA_INIT
1343         bool "Remote debugging over FireWire early on boot"
1344         depends on PCI && X86
1345         help
1346           If you want to debug problems which hang or crash the kernel early
1347           on boot and the crashing machine has a FireWire port, you can use
1348           this feature to remotely access the memory of the crashed machine
1349           over FireWire. This employs remote DMA as part of the OHCI1394
1350           specification which is now the standard for FireWire controllers.
1351
1352           With remote DMA, you can monitor the printk buffer remotely using
1353           firescope and access all memory below 4GB using fireproxy from gdb.
1354           Even controlling a kernel debugger is possible using remote DMA.
1355
1356           Usage:
1357
1358           If ohci1394_dma=early is used as boot parameter, it will initialize
1359           all OHCI1394 controllers which are found in the PCI config space.
1360
1361           As all changes to the FireWire bus such as enabling and disabling
1362           devices cause a bus reset and thereby disable remote DMA for all
1363           devices, be sure to have the cable plugged and FireWire enabled on
1364           the debugging host before booting the debug target for debugging.
1365
1366           This code (~1k) is freed after boot. By then, the firewire stack
1367           in charge of the OHCI-1394 controllers should be used instead.
1368
1369           See Documentation/debugging-via-ohci1394.txt for more information.
1370
1371 config FIREWIRE_OHCI_REMOTE_DMA
1372         bool "Remote debugging over FireWire with firewire-ohci"
1373         depends on FIREWIRE_OHCI
1374         help
1375           This option lets you use the FireWire bus for remote debugging
1376           with help of the firewire-ohci driver. It enables unfiltered
1377           remote DMA in firewire-ohci.
1378           See Documentation/debugging-via-ohci1394.txt for more information.
1379
1380           If unsure, say N.
1381
1382 config BUILD_DOCSRC
1383         bool "Build targets in Documentation/ tree"
1384         depends on HEADERS_CHECK
1385         help
1386           This option attempts to build objects from the source files in the
1387           kernel Documentation/ tree.
1388
1389           Say N if you are unsure.
1390
1391 config DYNAMIC_DEBUG
1392         bool "Enable dynamic printk() support"
1393         default n
1394         depends on PRINTK
1395         depends on DEBUG_FS
1396         help
1397
1398           Compiles debug level messages into the kernel, which would not
1399           otherwise be available at runtime. These messages can then be
1400           enabled/disabled based on various levels of scope - per source file,
1401           function, module, format string, and line number. This mechanism
1402           implicitly compiles in all pr_debug() and dev_dbg() calls, which
1403           enlarges the kernel text size by about 2%.
1404
1405           If a source file is compiled with DEBUG flag set, any
1406           pr_debug() calls in it are enabled by default, but can be
1407           disabled at runtime as below.  Note that DEBUG flag is
1408           turned on by many CONFIG_*DEBUG* options.
1409
1410           Usage:
1411
1412           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1413           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1414           filesystem must first be mounted before making use of this feature.
1415           We refer the control file as: <debugfs>/dynamic_debug/control. This
1416           file contains a list of the debug statements that can be enabled. The
1417           format for each line of the file is:
1418
1419                 filename:lineno [module]function flags format
1420
1421           filename : source file of the debug statement
1422           lineno : line number of the debug statement
1423           module : module that contains the debug statement
1424           function : function that contains the debug statement
1425           flags : '=p' means the line is turned 'on' for printing
1426           format : the format used for the debug statement
1427
1428           From a live system:
1429
1430                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1431                 # filename:lineno [module]function flags format
1432                 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1433                 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1434                 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
1435
1436           Example usage:
1437
1438                 // enable the message at line 1603 of file svcsock.c
1439                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1440                                                 <debugfs>/dynamic_debug/control
1441
1442                 // enable all the messages in file svcsock.c
1443                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1444                                                 <debugfs>/dynamic_debug/control
1445
1446                 // enable all the messages in the NFS server module
1447                 nullarbor:~ # echo -n 'module nfsd +p' >
1448                                                 <debugfs>/dynamic_debug/control
1449
1450                 // enable all 12 messages in the function svc_process()
1451                 nullarbor:~ # echo -n 'func svc_process +p' >
1452                                                 <debugfs>/dynamic_debug/control
1453
1454                 // disable all 12 messages in the function svc_process()
1455                 nullarbor:~ # echo -n 'func svc_process -p' >
1456                                                 <debugfs>/dynamic_debug/control
1457
1458           See Documentation/dynamic-debug-howto.txt for additional information.
1459
1460 config DMA_API_DEBUG
1461         bool "Enable debugging of DMA-API usage"
1462         depends on HAVE_DMA_API_DEBUG
1463         help
1464           Enable this option to debug the use of the DMA API by device drivers.
1465           With this option you will be able to detect common bugs in device
1466           drivers like double-freeing of DMA mappings or freeing mappings that
1467           were never allocated.
1468           This option causes a performance degredation.  Use only if you want
1469           to debug device drivers. If unsure, say N.
1470
1471 config ATOMIC64_SELFTEST
1472         bool "Perform an atomic64_t self-test at boot"
1473         help
1474           Enable this option to test the atomic64_t functions at boot.
1475
1476           If unsure, say N.
1477
1478 config ASYNC_RAID6_TEST
1479         tristate "Self test for hardware accelerated raid6 recovery"
1480         depends on ASYNC_RAID6_RECOV
1481         select ASYNC_MEMCPY
1482         ---help---
1483           This is a one-shot self test that permutes through the
1484           recovery of all the possible two disk failure scenarios for a
1485           N-disk array.  Recovery is performed with the asynchronous
1486           raid6 recovery routines, and will optionally use an offload
1487           engine if one is available.
1488
1489           If unsure, say N.
1490
1491 source "samples/Kconfig"
1492
1493 source "lib/Kconfig.kgdb"
1494
1495 source "lib/Kconfig.kmemcheck"
1496
1497 config TEST_STRING_HELPERS
1498         tristate "Test functions located in the string_helpers module at runtime"
1499
1500 config TEST_KSTRTOX
1501         tristate "Test kstrto*() family of functions at runtime"