linux/lib/Kconfig.debug
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   1
   2config PRINTK_TIME
   3        bool "Show timing information on printks"
   4        depends on PRINTK
   5        help
   6          Selecting this option causes time stamps of the printk()
   7          messages to be added to the output of the syslog() system
   8          call and at the console.
   9
  10          The timestamp is always recorded internally, and exported
  11          to /dev/kmsg. This flag just specifies if the timestamp should
  12          be included, not that the timestamp is recorded.
  13
  14          The behavior is also controlled by the kernel command line
  15          parameter printk.time=1. See Documentation/kernel-parameters.txt
  16
  17config DEFAULT_MESSAGE_LOGLEVEL
  18        int "Default message log level (1-7)"
  19        range 1 7
  20        default "4"
  21        help
  22          Default log level for printk statements with no specified priority.
  23
  24          This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
  25          that are auditing their logs closely may want to set it to a lower
  26          priority.
  27
  28config ENABLE_WARN_DEPRECATED
  29        bool "Enable __deprecated logic"
  30        default y
  31        help
  32          Enable the __deprecated logic in the kernel build.
  33          Disable this to suppress the "warning: 'foo' is deprecated
  34          (declared at kernel/power/somefile.c:1234)" messages.
  35
  36config ENABLE_MUST_CHECK
  37        bool "Enable __must_check logic"
  38        default y
  39        help
  40          Enable the __must_check logic in the kernel build.  Disable this to
  41          suppress the "warning: ignoring return value of 'foo', declared with
  42          attribute warn_unused_result" messages.
  43
  44config FRAME_WARN
  45        int "Warn for stack frames larger than (needs gcc 4.4)"
  46        range 0 8192
  47        default 1024 if !64BIT
  48        default 2048 if 64BIT
  49        help
  50          Tell gcc to warn at build time for stack frames larger than this.
  51          Setting this too low will cause a lot of warnings.
  52          Setting it to 0 disables the warning.
  53          Requires gcc 4.4
  54
  55config MAGIC_SYSRQ
  56        bool "Magic SysRq key"
  57        depends on !UML
  58        help
  59          If you say Y here, you will have some control over the system even
  60          if the system crashes for example during kernel debugging (e.g., you
  61          will be able to flush the buffer cache to disk, reboot the system
  62          immediately or dump some status information). This is accomplished
  63          by pressing various keys while holding SysRq (Alt+PrintScreen). It
  64          also works on a serial console (on PC hardware at least), if you
  65          send a BREAK and then within 5 seconds a command keypress. The
  66          keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  67          unless you really know what this hack does.
  68
  69config STRIP_ASM_SYMS
  70        bool "Strip assembler-generated symbols during link"
  71        default n
  72        help
  73          Strip internal assembler-generated symbols during a link (symbols
  74          that look like '.Lxxx') so they don't pollute the output of
  75          get_wchan() and suchlike.
  76
  77config READABLE_ASM
  78        bool "Generate readable assembler code"
  79        depends on DEBUG_KERNEL
  80        help
  81          Disable some compiler optimizations that tend to generate human unreadable
  82          assembler output. This may make the kernel slightly slower, but it helps
  83          to keep kernel developers who have to stare a lot at assembler listings
  84          sane.
  85
  86config UNUSED_SYMBOLS
  87        bool "Enable unused/obsolete exported symbols"
  88        default y if X86
  89        help
  90          Unused but exported symbols make the kernel needlessly bigger.  For
  91          that reason most of these unused exports will soon be removed.  This
  92          option is provided temporarily to provide a transition period in case
  93          some external kernel module needs one of these symbols anyway. If you
  94          encounter such a case in your module, consider if you are actually
  95          using the right API.  (rationale: since nobody in the kernel is using
  96          this in a module, there is a pretty good chance it's actually the
  97          wrong interface to use).  If you really need the symbol, please send a
  98          mail to the linux kernel mailing list mentioning the symbol and why
  99          you really need it, and what the merge plan to the mainline kernel for
 100          your module is.
 101
 102config DEBUG_FS
 103        bool "Debug Filesystem"
 104        help
 105          debugfs is a virtual file system that kernel developers use to put
 106          debugging files into.  Enable this option to be able to read and
 107          write to these files.
 108
 109          For detailed documentation on the debugfs API, see
 110          Documentation/DocBook/filesystems.
 111
 112          If unsure, say N.
 113
 114config HEADERS_CHECK
 115        bool "Run 'make headers_check' when building vmlinux"
 116        depends on !UML
 117        help
 118          This option will extract the user-visible kernel headers whenever
 119          building the kernel, and will run basic sanity checks on them to
 120          ensure that exported files do not attempt to include files which
 121          were not exported, etc.
 122
 123          If you're making modifications to header files which are
 124          relevant for userspace, say 'Y', and check the headers
 125          exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 126          your build tree), to make sure they're suitable.
 127
 128config DEBUG_SECTION_MISMATCH
 129        bool "Enable full Section mismatch analysis"
 130        help
 131          The section mismatch analysis checks if there are illegal
 132          references from one section to another section.
 133          During linktime or runtime, some sections are dropped;
 134          any use of code/data previously in these sections would
 135          most likely result in an oops.
 136          In the code, functions and variables are annotated with
 137          __init, __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
 159config DEBUG_KERNEL
 160        bool "Kernel debugging"
 161        help
 162          Say Y here if you are developing drivers or trying to debug and
 163          identify kernel problems.
 164
 165config DEBUG_SHIRQ
 166        bool "Debug shared IRQ handlers"
 167        depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 168        help
 169          Enable this to generate a spurious interrupt as soon as a shared
 170          interrupt handler is registered, and just before one is deregistered.
 171          Drivers ought to be able to handle interrupts coming in at those
 172          points; some don't and need to be caught.
 173
 174config LOCKUP_DETECTOR
 175        bool "Detect Hard and Soft Lockups"
 176        depends on DEBUG_KERNEL && !S390
 177        help
 178          Say Y here to enable the kernel to act as a watchdog to detect
 179          hard and soft lockups.
 180
 181          Softlockups are bugs that cause the kernel to loop in kernel
 182          mode for more than 20 seconds, without giving other tasks a
 183          chance to run.  The current stack trace is displayed upon
 184          detection and the system will stay locked up.
 185
 186          Hardlockups are bugs that cause the CPU to loop in kernel mode
 187          for more than 10 seconds, without letting other interrupts have a
 188          chance to run.  The current stack trace is displayed upon detection
 189          and the system will stay locked up.
 190
 191          The overhead should be minimal.  A periodic hrtimer runs to
 192          generate interrupts and kick the watchdog task every 4 seconds.
 193          An NMI is generated every 10 seconds or so to check for hardlockups.
 194
 195          The frequency of hrtimer and NMI events and the soft and hard lockup
 196          thresholds can be controlled through the sysctl watchdog_thresh.
 197
 198config HARDLOCKUP_DETECTOR
 199        def_bool y
 200        depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
 201        depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
 202
 203config 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
 214config 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
 221config 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
 238config 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
 245config PANIC_ON_OOPS
 246        bool "Panic on Oops"
 247        help
 248          Say Y here to enable the kernel to panic when it oopses. This
 249          has the same effect as setting oops=panic on the kernel command
 250          line.
 251
 252          This feature is useful to ensure that the kernel does not do
 253          anything erroneous after an oops which could result in data
 254          corruption or other issues.
 255
 256          Say N if unsure.
 257
 258config PANIC_ON_OOPS_VALUE
 259        int
 260        range 0 1
 261        default 0 if !PANIC_ON_OOPS
 262        default 1 if PANIC_ON_OOPS
 263
 264config DETECT_HUNG_TASK
 265        bool "Detect Hung Tasks"
 266        depends on DEBUG_KERNEL
 267        default LOCKUP_DETECTOR
 268        help
 269          Say Y here to enable the kernel to detect "hung tasks",
 270          which are bugs that cause the task to be stuck in
 271          uninterruptible "D" state indefinitiley.
 272
 273          When a hung task is detected, the kernel will print the
 274          current stack trace (which you should report), but the
 275          task will stay in uninterruptible state. If lockdep is
 276          enabled then all held locks will also be reported. This
 277          feature has negligible overhead.
 278
 279config DEFAULT_HUNG_TASK_TIMEOUT
 280        int "Default timeout for hung task detection (in seconds)"
 281        depends on DETECT_HUNG_TASK
 282        default 120
 283        help
 284          This option controls the default timeout (in seconds) used
 285          to determine when a task has become non-responsive and should
 286          be considered hung.
 287
 288          It can be adjusted at runtime via the kernel.hung_task_timeout_secs
 289          sysctl or by writing a value to
 290          /proc/sys/kernel/hung_task_timeout_secs.
 291
 292          A timeout of 0 disables the check.  The default is two minutes.
 293          Keeping the default should be fine in most cases.
 294
 295config BOOTPARAM_HUNG_TASK_PANIC
 296        bool "Panic (Reboot) On Hung Tasks"
 297        depends on DETECT_HUNG_TASK
 298        help
 299          Say Y here to enable the kernel to panic on "hung tasks",
 300          which are bugs that cause the kernel to leave a task stuck
 301          in uninterruptible "D" state.
 302
 303          The panic can be used in combination with panic_timeout,
 304          to cause the system to reboot automatically after a
 305          hung task has been detected. This feature is useful for
 306          high-availability systems that have uptime guarantees and
 307          where a hung tasks must be resolved ASAP.
 308
 309          Say N if unsure.
 310
 311config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 312        int
 313        depends on DETECT_HUNG_TASK
 314        range 0 1
 315        default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 316        default 1 if BOOTPARAM_HUNG_TASK_PANIC
 317
 318config SCHED_DEBUG
 319        bool "Collect scheduler debugging info"
 320        depends on DEBUG_KERNEL && PROC_FS
 321        default y
 322        help
 323          If you say Y here, the /proc/sched_debug file will be provided
 324          that can help debug the scheduler. The runtime overhead of this
 325          option is minimal.
 326
 327config SCHEDSTATS
 328        bool "Collect scheduler statistics"
 329        depends on DEBUG_KERNEL && PROC_FS
 330        help
 331          If you say Y here, additional code will be inserted into the
 332          scheduler and related routines to collect statistics about
 333          scheduler behavior and provide them in /proc/schedstat.  These
 334          stats may be useful for both tuning and debugging the scheduler
 335          If you aren't debugging the scheduler or trying to tune a specific
 336          application, you can say N to avoid the very slight overhead
 337          this adds.
 338
 339config TIMER_STATS
 340        bool "Collect kernel timers statistics"
 341        depends on DEBUG_KERNEL && PROC_FS
 342        help
 343          If you say Y here, additional code will be inserted into the
 344          timer routines to collect statistics about kernel timers being
 345          reprogrammed. The statistics can be read from /proc/timer_stats.
 346          The statistics collection is started by writing 1 to /proc/timer_stats,
 347          writing 0 stops it. This feature is useful to collect information
 348          about timer usage patterns in kernel and userspace. This feature
 349          is lightweight if enabled in the kernel config but not activated
 350          (it defaults to deactivated on bootup and will only be activated
 351          if some application like powertop activates it explicitly).
 352
 353config DEBUG_OBJECTS
 354        bool "Debug object operations"
 355        depends on DEBUG_KERNEL
 356        help
 357          If you say Y here, additional code will be inserted into the
 358          kernel to track the life time of various objects and validate
 359          the operations on those objects.
 360
 361config DEBUG_OBJECTS_SELFTEST
 362        bool "Debug objects selftest"
 363        depends on DEBUG_OBJECTS
 364        help
 365          This enables the selftest of the object debug code.
 366
 367config DEBUG_OBJECTS_FREE
 368        bool "Debug objects in freed memory"
 369        depends on DEBUG_OBJECTS
 370        help
 371          This enables checks whether a k/v free operation frees an area
 372          which contains an object which has not been deactivated
 373          properly. This can make kmalloc/kfree-intensive workloads
 374          much slower.
 375
 376config DEBUG_OBJECTS_TIMERS
 377        bool "Debug timer objects"
 378        depends on DEBUG_OBJECTS
 379        help
 380          If you say Y here, additional code will be inserted into the
 381          timer routines to track the life time of timer objects and
 382          validate the timer operations.
 383
 384config DEBUG_OBJECTS_WORK
 385        bool "Debug work objects"
 386        depends on DEBUG_OBJECTS
 387        help
 388          If you say Y here, additional code will be inserted into the
 389          work queue routines to track the life time of work objects and
 390          validate the work operations.
 391
 392config DEBUG_OBJECTS_RCU_HEAD
 393        bool "Debug RCU callbacks objects"
 394        depends on DEBUG_OBJECTS
 395        help
 396          Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 397
 398config DEBUG_OBJECTS_PERCPU_COUNTER
 399        bool "Debug percpu counter objects"
 400        depends on DEBUG_OBJECTS
 401        help
 402          If you say Y here, additional code will be inserted into the
 403          percpu counter routines to track the life time of percpu counter
 404          objects and validate the percpu counter operations.
 405
 406config DEBUG_OBJECTS_ENABLE_DEFAULT
 407        int "debug_objects bootup default value (0-1)"
 408        range 0 1
 409        default "1"
 410        depends on DEBUG_OBJECTS
 411        help
 412          Debug objects boot parameter default value
 413
 414config DEBUG_SLAB
 415        bool "Debug slab memory allocations"
 416        depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 417        help
 418          Say Y here to have the kernel do limited verification on memory
 419          allocation as well as poisoning memory on free to catch use of freed
 420          memory. This can make kmalloc/kfree-intensive workloads much slower.
 421
 422config DEBUG_SLAB_LEAK
 423        bool "Memory leak debugging"
 424        depends on DEBUG_SLAB
 425
 426config SLUB_DEBUG_ON
 427        bool "SLUB debugging on by default"
 428        depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 429        default n
 430        help
 431          Boot with debugging on by default. SLUB boots by default with
 432          the runtime debug capabilities switched off. Enabling this is
 433          equivalent to specifying the "slub_debug" parameter on boot.
 434          There is no support for more fine grained debug control like
 435          possible with slub_debug=xxx. SLUB debugging may be switched
 436          off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 437          "slub_debug=-".
 438
 439config SLUB_STATS
 440        default n
 441        bool "Enable SLUB performance statistics"
 442        depends on SLUB && SYSFS
 443        help
 444          SLUB statistics are useful to debug SLUBs allocation behavior in
 445          order find ways to optimize the allocator. This should never be
 446          enabled for production use since keeping statistics slows down
 447          the allocator by a few percentage points. The slabinfo command
 448          supports the determination of the most active slabs to figure
 449          out which slabs are relevant to a particular load.
 450          Try running: slabinfo -DA
 451
 452config HAVE_DEBUG_KMEMLEAK
 453        bool
 454
 455config DEBUG_KMEMLEAK
 456        bool "Kernel memory leak detector"
 457        depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
 458        select DEBUG_FS
 459        select STACKTRACE if STACKTRACE_SUPPORT
 460        select KALLSYMS
 461        select CRC32
 462        help
 463          Say Y here if you want to enable the memory leak
 464          detector. The memory allocation/freeing is traced in a way
 465          similar to the Boehm's conservative garbage collector, the
 466          difference being that the orphan objects are not freed but
 467          only shown in /sys/kernel/debug/kmemleak. Enabling this
 468          feature will introduce an overhead to memory
 469          allocations. See Documentation/kmemleak.txt for more
 470          details.
 471
 472          Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 473          of finding leaks due to the slab objects poisoning.
 474
 475          In order to access the kmemleak file, debugfs needs to be
 476          mounted (usually at /sys/kernel/debug).
 477
 478config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 479        int "Maximum kmemleak early log entries"
 480        depends on DEBUG_KMEMLEAK
 481        range 200 40000
 482        default 400
 483        help
 484          Kmemleak must track all the memory allocations to avoid
 485          reporting false positives. Since memory may be allocated or
 486          freed before kmemleak is initialised, an early log buffer is
 487          used to store these actions. If kmemleak reports "early log
 488          buffer exceeded", please increase this value.
 489
 490config DEBUG_KMEMLEAK_TEST
 491        tristate "Simple test for the kernel memory leak detector"
 492        depends on DEBUG_KMEMLEAK && m
 493        help
 494          This option enables a module that explicitly leaks memory.
 495
 496          If unsure, say N.
 497
 498config DEBUG_KMEMLEAK_DEFAULT_OFF
 499        bool "Default kmemleak to off"
 500        depends on DEBUG_KMEMLEAK
 501        help
 502          Say Y here to disable kmemleak by default. It can then be enabled
 503          on the command line via kmemleak=on.
 504
 505config DEBUG_PREEMPT
 506        bool "Debug preemptible kernel"
 507        depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 508        default y
 509        help
 510          If you say Y here then the kernel will use a debug variant of the
 511          commonly used smp_processor_id() function and will print warnings
 512          if kernel code uses it in a preemption-unsafe way. Also, the kernel
 513          will detect preemption count underflows.
 514
 515config DEBUG_RT_MUTEXES
 516        bool "RT Mutex debugging, deadlock detection"
 517        depends on DEBUG_KERNEL && RT_MUTEXES
 518        help
 519         This allows rt mutex semantics violations and rt mutex related
 520         deadlocks (lockups) to be detected and reported automatically.
 521
 522config DEBUG_PI_LIST
 523        bool
 524        default y
 525        depends on DEBUG_RT_MUTEXES
 526
 527config RT_MUTEX_TESTER
 528        bool "Built-in scriptable tester for rt-mutexes"
 529        depends on DEBUG_KERNEL && RT_MUTEXES
 530        help
 531          This option enables a rt-mutex tester.
 532
 533config DEBUG_SPINLOCK
 534        bool "Spinlock and rw-lock debugging: basic checks"
 535        depends on DEBUG_KERNEL
 536        select UNINLINE_SPIN_UNLOCK
 537        help
 538          Say Y here and build SMP to catch missing spinlock initialization
 539          and certain other kinds of spinlock errors commonly made.  This is
 540          best used in conjunction with the NMI watchdog so that spinlock
 541          deadlocks are also debuggable.
 542
 543config DEBUG_MUTEXES
 544        bool "Mutex debugging: basic checks"
 545        depends on DEBUG_KERNEL
 546        help
 547         This feature allows mutex semantics violations to be detected and
 548         reported.
 549
 550config DEBUG_LOCK_ALLOC
 551        bool "Lock debugging: detect incorrect freeing of live locks"
 552        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 553        select DEBUG_SPINLOCK
 554        select DEBUG_MUTEXES
 555        select LOCKDEP
 556        help
 557         This feature will check whether any held lock (spinlock, rwlock,
 558         mutex or rwsem) is incorrectly freed by the kernel, via any of the
 559         memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 560         vfree(), etc.), whether a live lock is incorrectly reinitialized via
 561         spin_lock_init()/mutex_init()/etc., or whether there is any lock
 562         held during task exit.
 563
 564config PROVE_LOCKING
 565        bool "Lock debugging: prove locking correctness"
 566        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 567        select LOCKDEP
 568        select DEBUG_SPINLOCK
 569        select DEBUG_MUTEXES
 570        select DEBUG_LOCK_ALLOC
 571        select TRACE_IRQFLAGS
 572        default n
 573        help
 574         This feature enables the kernel to prove that all locking
 575         that occurs in the kernel runtime is mathematically
 576         correct: that under no circumstance could an arbitrary (and
 577         not yet triggered) combination of observed locking
 578         sequences (on an arbitrary number of CPUs, running an
 579         arbitrary number of tasks and interrupt contexts) cause a
 580         deadlock.
 581
 582         In short, this feature enables the kernel to report locking
 583         related deadlocks before they actually occur.
 584
 585         The proof does not depend on how hard and complex a
 586         deadlock scenario would be to trigger: how many
 587         participant CPUs, tasks and irq-contexts would be needed
 588         for it to trigger. The proof also does not depend on
 589         timing: if a race and a resulting deadlock is possible
 590         theoretically (no matter how unlikely the race scenario
 591         is), it will be proven so and will immediately be
 592         reported by the kernel (once the event is observed that
 593         makes the deadlock theoretically possible).
 594
 595         If a deadlock is impossible (i.e. the locking rules, as
 596         observed by the kernel, are mathematically correct), the
 597         kernel reports nothing.
 598
 599         NOTE: this feature can also be enabled for rwlocks, mutexes
 600         and rwsems - in which case all dependencies between these
 601         different locking variants are observed and mapped too, and
 602         the proof of observed correctness is also maintained for an
 603         arbitrary combination of these separate locking variants.
 604
 605         For more details, see Documentation/lockdep-design.txt.
 606
 607config LOCKDEP
 608        bool
 609        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 610        select STACKTRACE
 611        select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 612        select KALLSYMS
 613        select KALLSYMS_ALL
 614
 615config LOCK_STAT
 616        bool "Lock usage statistics"
 617        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 618        select LOCKDEP
 619        select DEBUG_SPINLOCK
 620        select DEBUG_MUTEXES
 621        select DEBUG_LOCK_ALLOC
 622        default n
 623        help
 624         This feature enables tracking lock contention points
 625
 626         For more details, see Documentation/lockstat.txt
 627
 628         This also enables lock events required by "perf lock",
 629         subcommand of perf.
 630         If you want to use "perf lock", you also need to turn on
 631         CONFIG_EVENT_TRACING.
 632
 633         CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 634         (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 635
 636config DEBUG_LOCKDEP
 637        bool "Lock dependency engine debugging"
 638        depends on DEBUG_KERNEL && LOCKDEP
 639        help
 640          If you say Y here, the lock dependency engine will do
 641          additional runtime checks to debug itself, at the price
 642          of more runtime overhead.
 643
 644config TRACE_IRQFLAGS
 645        bool
 646        help
 647          Enables hooks to interrupt enabling and disabling for
 648          either tracing or lock debugging.
 649
 650config DEBUG_ATOMIC_SLEEP
 651        bool "Sleep inside atomic section checking"
 652        select PREEMPT_COUNT
 653        depends on DEBUG_KERNEL
 654        help
 655          If you say Y here, various routines which may sleep will become very
 656          noisy if they are called inside atomic sections: when a spinlock is
 657          held, inside an rcu read side critical section, inside preempt disabled
 658          sections, inside an interrupt, etc...
 659
 660config DEBUG_LOCKING_API_SELFTESTS
 661        bool "Locking API boot-time self-tests"
 662        depends on DEBUG_KERNEL
 663        help
 664          Say Y here if you want the kernel to run a short self-test during
 665          bootup. The self-test checks whether common types of locking bugs
 666          are detected by debugging mechanisms or not. (if you disable
 667          lock debugging then those bugs wont be detected of course.)
 668          The following locking APIs are covered: spinlocks, rwlocks,
 669          mutexes and rwsems.
 670
 671config STACKTRACE
 672        bool
 673        depends on STACKTRACE_SUPPORT
 674
 675config DEBUG_STACK_USAGE
 676        bool "Stack utilization instrumentation"
 677        depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
 678        help
 679          Enables the display of the minimum amount of free stack which each
 680          task has ever had available in the sysrq-T and sysrq-P debug output.
 681
 682          This option will slow down process creation somewhat.
 683
 684config DEBUG_KOBJECT
 685        bool "kobject debugging"
 686        depends on DEBUG_KERNEL
 687        help
 688          If you say Y here, some extra kobject debugging messages will be sent
 689          to the syslog. 
 690
 691config DEBUG_HIGHMEM
 692        bool "Highmem debugging"
 693        depends on DEBUG_KERNEL && HIGHMEM
 694        help
 695          This options enables addition error checking for high memory systems.
 696          Disable for production systems.
 697
 698config HAVE_DEBUG_BUGVERBOSE
 699        bool
 700
 701config DEBUG_BUGVERBOSE
 702        bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
 703        depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
 704        default y
 705        help
 706          Say Y here to make BUG() panics output the file name and line number
 707          of the BUG call as well as the EIP and oops trace.  This aids
 708          debugging but costs about 70-100K of memory.
 709
 710config DEBUG_INFO
 711        bool "Compile the kernel with debug info"
 712        depends on DEBUG_KERNEL
 713        help
 714          If you say Y here the resulting kernel image will include
 715          debugging info resulting in a larger kernel image.
 716          This adds debug symbols to the kernel and modules (gcc -g), and
 717          is needed if you intend to use kernel crashdump or binary object
 718          tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 719          Say Y here only if you plan to debug the kernel.
 720
 721          If unsure, say N.
 722
 723config DEBUG_INFO_REDUCED
 724        bool "Reduce debugging information"
 725        depends on DEBUG_INFO
 726        help
 727          If you say Y here gcc is instructed to generate less debugging
 728          information for structure types. This means that tools that
 729          need full debugging information (like kgdb or systemtap) won't
 730          be happy. But if you merely need debugging information to
 731          resolve line numbers there is no loss. Advantage is that
 732          build directory object sizes shrink dramatically over a full
 733          DEBUG_INFO build and compile times are reduced too.
 734          Only works with newer gcc versions.
 735
 736config DEBUG_VM
 737        bool "Debug VM"
 738        depends on DEBUG_KERNEL
 739        help
 740          Enable this to turn on extended checks in the virtual-memory system
 741          that may impact performance.
 742
 743          If unsure, say N.
 744
 745config DEBUG_VM_RB
 746        bool "Debug VM red-black trees"
 747        depends on DEBUG_VM
 748        help
 749          Enable this to turn on more extended checks in the virtual-memory
 750          system that may impact performance.
 751
 752          If unsure, say N.
 753
 754config DEBUG_VIRTUAL
 755        bool "Debug VM translations"
 756        depends on DEBUG_KERNEL && X86
 757        help
 758          Enable some costly sanity checks in virtual to page code. This can
 759          catch mistakes with virt_to_page() and friends.
 760
 761          If unsure, say N.
 762
 763config DEBUG_NOMMU_REGIONS
 764        bool "Debug the global anon/private NOMMU mapping region tree"
 765        depends on DEBUG_KERNEL && !MMU
 766        help
 767          This option causes the global tree of anonymous and private mapping
 768          regions to be regularly checked for invalid topology.
 769
 770config DEBUG_WRITECOUNT
 771        bool "Debug filesystem writers count"
 772        depends on DEBUG_KERNEL
 773        help
 774          Enable this to catch wrong use of the writers count in struct
 775          vfsmount.  This will increase the size of each file struct by
 776          32 bits.
 777
 778          If unsure, say N.
 779
 780config DEBUG_MEMORY_INIT
 781        bool "Debug memory initialisation" if EXPERT
 782        default !EXPERT
 783        help
 784          Enable this for additional checks during memory initialisation.
 785          The sanity checks verify aspects of the VM such as the memory model
 786          and other information provided by the architecture. Verbose
 787          information will be printed at KERN_DEBUG loglevel depending
 788          on the mminit_loglevel= command-line option.
 789
 790          If unsure, say Y
 791
 792config DEBUG_LIST
 793        bool "Debug linked list manipulation"
 794        depends on DEBUG_KERNEL
 795        help
 796          Enable this to turn on extended checks in the linked-list
 797          walking routines.
 798
 799          If unsure, say N.
 800
 801config TEST_LIST_SORT
 802        bool "Linked list sorting test"
 803        depends on DEBUG_KERNEL
 804        help
 805          Enable this to turn on 'list_sort()' function test. This test is
 806          executed only once during system boot, so affects only boot time.
 807
 808          If unsure, say N.
 809
 810config DEBUG_SG
 811        bool "Debug SG table operations"
 812        depends on DEBUG_KERNEL
 813        help
 814          Enable this to turn on checks on scatter-gather tables. This can
 815          help find problems with drivers that do not properly initialize
 816          their sg tables.
 817
 818          If unsure, say N.
 819
 820config DEBUG_NOTIFIERS
 821        bool "Debug notifier call chains"
 822        depends on DEBUG_KERNEL
 823        help
 824          Enable this to turn on sanity checking for notifier call chains.
 825          This is most useful for kernel developers to make sure that
 826          modules properly unregister themselves from notifier chains.
 827          This is a relatively cheap check but if you care about maximum
 828          performance, say N.
 829
 830config DEBUG_CREDENTIALS
 831        bool "Debug credential management"
 832        depends on DEBUG_KERNEL
 833        help
 834          Enable this to turn on some debug checking for credential
 835          management.  The additional code keeps track of the number of
 836          pointers from task_structs to any given cred struct, and checks to
 837          see that this number never exceeds the usage count of the cred
 838          struct.
 839
 840          Furthermore, if SELinux is enabled, this also checks that the
 841          security pointer in the cred struct is never seen to be invalid.
 842
 843          If unsure, say N.
 844
 845#
 846# Select this config option from the architecture Kconfig, if it
 847# is preferred to always offer frame pointers as a config
 848# option on the architecture (regardless of KERNEL_DEBUG):
 849#
 850config ARCH_WANT_FRAME_POINTERS
 851        bool
 852        help
 853
 854config FRAME_POINTER
 855        bool "Compile the kernel with frame pointers"
 856        depends on DEBUG_KERNEL && \
 857                (CRIS || M68K || FRV || UML || \
 858                 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
 859                ARCH_WANT_FRAME_POINTERS
 860        default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 861        help
 862          If you say Y here the resulting kernel image will be slightly
 863          larger and slower, but it gives very useful debugging information
 864          in case of kernel bugs. (precise oopses/stacktraces/warnings)
 865
 866config BOOT_PRINTK_DELAY
 867        bool "Delay each boot printk message by N milliseconds"
 868        depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 869        help
 870          This build option allows you to read kernel boot messages
 871          by inserting a short delay after each one.  The delay is
 872          specified in milliseconds on the kernel command line,
 873          using "boot_delay=N".
 874
 875          It is likely that you would also need to use "lpj=M" to preset
 876          the "loops per jiffie" value.
 877          See a previous boot log for the "lpj" value to use for your
 878          system, and then set "lpj=M" before setting "boot_delay=N".
 879          NOTE:  Using this option may adversely affect SMP systems.
 880          I.e., processors other than the first one may not boot up.
 881          BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
 882          what it believes to be lockup conditions.
 883
 884menu "RCU Debugging"
 885
 886config PROVE_RCU
 887        bool "RCU debugging: prove RCU correctness"
 888        depends on PROVE_LOCKING
 889        default n
 890        help
 891         This feature enables lockdep extensions that check for correct
 892         use of RCU APIs.  This is currently under development.  Say Y
 893         if you want to debug RCU usage or help work on the PROVE_RCU
 894         feature.
 895
 896         Say N if you are unsure.
 897
 898config PROVE_RCU_REPEATEDLY
 899        bool "RCU debugging: don't disable PROVE_RCU on first splat"
 900        depends on PROVE_RCU
 901        default n
 902        help
 903         By itself, PROVE_RCU will disable checking upon issuing the
 904         first warning (or "splat").  This feature prevents such
 905         disabling, allowing multiple RCU-lockdep warnings to be printed
 906         on a single reboot.
 907
 908         Say Y to allow multiple RCU-lockdep warnings per boot.
 909
 910         Say N if you are unsure.
 911
 912config PROVE_RCU_DELAY
 913        bool "RCU debugging: preemptible RCU race provocation"
 914        depends on DEBUG_KERNEL && PREEMPT_RCU
 915        default n
 916        help
 917         There is a class of races that involve an unlikely preemption
 918         of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
 919         been set to INT_MIN.  This feature inserts a delay at that
 920         point to increase the probability of these races.
 921
 922         Say Y to increase probability of preemption of __rcu_read_unlock().
 923
 924         Say N if you are unsure.
 925
 926config SPARSE_RCU_POINTER
 927        bool "RCU debugging: sparse-based checks for pointer usage"
 928        default n
 929        help
 930         This feature enables the __rcu sparse annotation for
 931         RCU-protected pointers.  This annotation will cause sparse
 932         to flag any non-RCU used of annotated pointers.  This can be
 933         helpful when debugging RCU usage.  Please note that this feature
 934         is not intended to enforce code cleanliness; it is instead merely
 935         a debugging aid.
 936
 937         Say Y to make sparse flag questionable use of RCU-protected pointers
 938
 939         Say N if you are unsure.
 940
 941config RCU_TORTURE_TEST
 942        tristate "torture tests for RCU"
 943        depends on DEBUG_KERNEL
 944        default n
 945        help
 946          This option provides a kernel module that runs torture tests
 947          on the RCU infrastructure.  The kernel module may be built
 948          after the fact on the running kernel to be tested, if desired.
 949
 950          Say Y here if you want RCU torture tests to be built into
 951          the kernel.
 952          Say M if you want the RCU torture tests to build as a module.
 953          Say N if you are unsure.
 954
 955config RCU_TORTURE_TEST_RUNNABLE
 956        bool "torture tests for RCU runnable by default"
 957        depends on RCU_TORTURE_TEST = y
 958        default n
 959        help
 960          This option provides a way to build the RCU torture tests
 961          directly into the kernel without them starting up at boot
 962          time.  You can use /proc/sys/kernel/rcutorture_runnable
 963          to manually override this setting.  This /proc file is
 964          available only when the RCU torture tests have been built
 965          into the kernel.
 966
 967          Say Y here if you want the RCU torture tests to start during
 968          boot (you probably don't).
 969          Say N here if you want the RCU torture tests to start only
 970          after being manually enabled via /proc.
 971
 972config RCU_CPU_STALL_TIMEOUT
 973        int "RCU CPU stall timeout in seconds"
 974        depends on RCU_STALL_COMMON
 975        range 3 300
 976        default 21
 977        help
 978          If a given RCU grace period extends more than the specified
 979          number of seconds, a CPU stall warning is printed.  If the
 980          RCU grace period persists, additional CPU stall warnings are
 981          printed at more widely spaced intervals.
 982
 983config RCU_CPU_STALL_VERBOSE
 984        bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 985        depends on TREE_PREEMPT_RCU
 986        default y
 987        help
 988          This option causes RCU to printk detailed per-task information
 989          for any tasks that are stalling the current RCU grace period.
 990
 991          Say N if you are unsure.
 992
 993          Say Y if you want to enable such checks.
 994
 995config RCU_CPU_STALL_INFO
 996        bool "Print additional diagnostics on RCU CPU stall"
 997        depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
 998        default n
 999        help
1000          For each stalled CPU that is aware of the current RCU grace
1001          period, print out additional per-CPU diagnostic information
1002          regarding scheduling-clock ticks, idle state, and,
1003          for RCU_FAST_NO_HZ kernels, idle-entry state.
1004
1005          Say N if you are unsure.
1006
1007          Say Y if you want to enable such diagnostics.
1008
1009config RCU_TRACE
1010        bool "Enable tracing for RCU"
1011        depends on DEBUG_KERNEL
1012        select TRACE_CLOCK
1013        help
1014          This option provides tracing in RCU which presents stats
1015          in debugfs for debugging RCU implementation.
1016
1017          Say Y here if you want to enable RCU tracing
1018          Say N if you are unsure.
1019
1020endmenu # "RCU Debugging"
1021
1022config KPROBES_SANITY_TEST
1023        bool "Kprobes sanity tests"
1024        depends on DEBUG_KERNEL
1025        depends on KPROBES
1026        default n
1027        help
1028          This option provides for testing basic kprobes functionality on
1029          boot. A sample kprobe, jprobe and kretprobe are inserted and
1030          verified for functionality.
1031
1032          Say N if you are unsure.
1033
1034config BACKTRACE_SELF_TEST
1035        tristate "Self test for the backtrace code"
1036        depends on DEBUG_KERNEL
1037        default n
1038        help
1039          This option provides a kernel module that can be used to test
1040          the kernel stack backtrace code. This option is not useful
1041          for distributions or general kernels, but only for kernel
1042          developers working on architecture code.
1043
1044          Note that if you want to also test saved backtraces, you will
1045          have to enable STACKTRACE as well.
1046
1047          Say N if you are unsure.
1048
1049config DEBUG_BLOCK_EXT_DEVT
1050        bool "Force extended block device numbers and spread them"
1051        depends on DEBUG_KERNEL
1052        depends on BLOCK
1053        default n
1054        help
1055          BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1056          SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1057          YOU ARE DOING.  Distros, please enable this and fix whatever
1058          is broken.
1059
1060          Conventionally, block device numbers are allocated from
1061          predetermined contiguous area.  However, extended block area
1062          may introduce non-contiguous block device numbers.  This
1063          option forces most block device numbers to be allocated from
1064          the extended space and spreads them to discover kernel or
1065          userland code paths which assume predetermined contiguous
1066          device number allocation.
1067
1068          Note that turning on this debug option shuffles all the
1069          device numbers for all IDE and SCSI devices including libata
1070          ones, so root partition specified using device number
1071          directly (via rdev or root=MAJ:MIN) won't work anymore.
1072          Textual device names (root=/dev/sdXn) will continue to work.
1073
1074          Say N if you are unsure.
1075
1076config DEBUG_FORCE_WEAK_PER_CPU
1077        bool "Force weak per-cpu definitions"
1078        depends on DEBUG_KERNEL
1079        help
1080          s390 and alpha require percpu variables in modules to be
1081          defined weak to work around addressing range issue which
1082          puts the following two restrictions on percpu variable
1083          definitions.
1084
1085          1. percpu symbols must be unique whether static or not
1086          2. percpu variables can't be defined inside a function
1087
1088          To ensure that generic code follows the above rules, this
1089          option forces all percpu variables to be defined as weak.
1090
1091config DEBUG_PER_CPU_MAPS
1092        bool "Debug access to per_cpu maps"
1093        depends on DEBUG_KERNEL
1094        depends on SMP
1095        help
1096          Say Y to verify that the per_cpu map being accessed has
1097          been set up. This adds a fair amount of code to kernel memory
1098          and decreases performance.
1099
1100          Say N if unsure.
1101
1102config LKDTM
1103        tristate "Linux Kernel Dump Test Tool Module"
1104        depends on DEBUG_FS
1105        depends on BLOCK
1106        default n
1107        help
1108        This module enables testing of the different dumping mechanisms by
1109        inducing system failures at predefined crash points.
1110        If you don't need it: say N
1111        Choose M here to compile this code as a module. The module will be
1112        called lkdtm.
1113
1114        Documentation on how to use the module can be found in
1115        Documentation/fault-injection/provoke-crashes.txt
1116
1117config NOTIFIER_ERROR_INJECTION
1118        tristate "Notifier error injection"
1119        depends on DEBUG_KERNEL
1120        select DEBUG_FS
1121        help
1122          This option provides the ability to inject artificial errors to
1123          specified notifier chain callbacks. It is useful to test the error
1124          handling of notifier call chain failures.
1125
1126          Say N if unsure.
1127
1128config CPU_NOTIFIER_ERROR_INJECT
1129        tristate "CPU notifier error injection module"
1130        depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1131        help
1132          This option provides a kernel module that can be used to test
1133          the error handling of the cpu notifiers by injecting artificial
1134          errors to CPU notifier chain callbacks.  It is controlled through
1135          debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1136
1137          If the notifier call chain should be failed with some events
1138          notified, write the error code to "actions/<notifier event>/error".
1139
1140          Example: Inject CPU offline error (-1 == -EPERM)
1141
1142          # cd /sys/kernel/debug/notifier-error-inject/cpu
1143          # echo -1 > actions/CPU_DOWN_PREPARE/error
1144          # echo 0 > /sys/devices/system/cpu/cpu1/online
1145          bash: echo: write error: Operation not permitted
1146
1147          To compile this code as a module, choose M here: the module will
1148          be called cpu-notifier-error-inject.
1149
1150          If unsure, say N.
1151
1152config PM_NOTIFIER_ERROR_INJECT
1153        tristate "PM notifier error injection module"
1154        depends on PM && NOTIFIER_ERROR_INJECTION
1155        default m if PM_DEBUG
1156        help
1157          This option provides the ability to inject artificial errors to
1158          PM notifier chain callbacks.  It is controlled through debugfs
1159          interface /sys/kernel/debug/notifier-error-inject/pm
1160
1161          If the notifier call chain should be failed with some events
1162          notified, write the error code to "actions/<notifier event>/error".
1163
1164          Example: Inject PM suspend error (-12 = -ENOMEM)
1165
1166          # cd /sys/kernel/debug/notifier-error-inject/pm/
1167          # echo -12 > actions/PM_SUSPEND_PREPARE/error
1168          # echo mem > /sys/power/state
1169          bash: echo: write error: Cannot allocate memory
1170
1171          To compile this code as a module, choose M here: the module will
1172          be called pm-notifier-error-inject.
1173
1174          If unsure, say N.
1175
1176config MEMORY_NOTIFIER_ERROR_INJECT
1177        tristate "Memory hotplug notifier error injection module"
1178        depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1179        help
1180          This option provides the ability to inject artificial errors to
1181          memory hotplug notifier chain callbacks.  It is controlled through
1182          debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
1183
1184          If the notifier call chain should be failed with some events
1185          notified, write the error code to "actions/<notifier event>/error".
1186
1187          Example: Inject memory hotplug offline error (-12 == -ENOMEM)
1188
1189          # cd /sys/kernel/debug/notifier-error-inject/memory
1190          # echo -12 > actions/MEM_GOING_OFFLINE/error
1191          # echo offline > /sys/devices/system/memory/memoryXXX/state
1192          bash: echo: write error: Cannot allocate memory
1193
1194          To compile this code as a module, choose M here: the module will
1195          be called pSeries-reconfig-notifier-error-inject.
1196
1197          If unsure, say N.
1198
1199config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1200        tristate "OF reconfig notifier error injection module"
1201        depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1202        help
1203          This option provides the ability to inject artificial errors to
1204          OF reconfig notifier chain callbacks.  It is controlled
1205          through debugfs interface under
1206          /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1207
1208          If the notifier call chain should be failed with some events
1209          notified, write the error code to "actions/<notifier event>/error".
1210
1211          To compile this code as a module, choose M here: the module will
1212          be called memory-notifier-error-inject.
1213
1214          If unsure, say N.
1215
1216config FAULT_INJECTION
1217        bool "Fault-injection framework"
1218        depends on DEBUG_KERNEL
1219        help
1220          Provide fault-injection framework.
1221          For more details, see Documentation/fault-injection/.
1222
1223config FAILSLAB
1224        bool "Fault-injection capability for kmalloc"
1225        depends on FAULT_INJECTION
1226        depends on SLAB || SLUB
1227        help
1228          Provide fault-injection capability for kmalloc.
1229
1230config FAIL_PAGE_ALLOC
1231        bool "Fault-injection capabilitiy for alloc_pages()"
1232        depends on FAULT_INJECTION
1233        help
1234          Provide fault-injection capability for alloc_pages().
1235
1236config FAIL_MAKE_REQUEST
1237        bool "Fault-injection capability for disk IO"
1238        depends on FAULT_INJECTION && BLOCK
1239        help
1240          Provide fault-injection capability for disk IO.
1241
1242config FAIL_IO_TIMEOUT
1243        bool "Fault-injection capability for faking disk interrupts"
1244        depends on FAULT_INJECTION && BLOCK
1245        help
1246          Provide fault-injection capability on end IO handling. This
1247          will make the block layer "forget" an interrupt as configured,
1248          thus exercising the error handling.
1249
1250          Only works with drivers that use the generic timeout handling,
1251          for others it wont do anything.
1252
1253config FAIL_MMC_REQUEST
1254        bool "Fault-injection capability for MMC IO"
1255        select DEBUG_FS
1256        depends on FAULT_INJECTION && MMC
1257        help
1258          Provide fault-injection capability for MMC IO.
1259          This will make the mmc core return data errors. This is
1260          useful to test the error handling in the mmc block device
1261          and to test how the mmc host driver handles retries from
1262          the block device.
1263
1264config FAULT_INJECTION_DEBUG_FS
1265        bool "Debugfs entries for fault-injection capabilities"
1266        depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1267        help
1268          Enable configuration of fault-injection capabilities via debugfs.
1269
1270config FAULT_INJECTION_STACKTRACE_FILTER
1271        bool "stacktrace filter for fault-injection capabilities"
1272        depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1273        depends on !X86_64
1274        select STACKTRACE
1275        select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1276        help
1277          Provide stacktrace filter for fault-injection capabilities
1278
1279config LATENCYTOP
1280        bool "Latency measuring infrastructure"
1281        depends on HAVE_LATENCYTOP_SUPPORT
1282        depends on DEBUG_KERNEL
1283        depends on STACKTRACE_SUPPORT
1284        depends on PROC_FS
1285        select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1286        select KALLSYMS
1287        select KALLSYMS_ALL
1288        select STACKTRACE
1289        select SCHEDSTATS
1290        select SCHED_DEBUG
1291        help
1292          Enable this option if you want to use the LatencyTOP tool
1293          to find out which userspace is blocking on what kernel operations.
1294
1295source mm/Kconfig.debug
1296source kernel/trace/Kconfig
1297
1298config RBTREE_TEST
1299        tristate "Red-Black tree test"
1300        depends on m && DEBUG_KERNEL
1301        help
1302          A benchmark measuring the performance of the rbtree library.
1303          Also includes rbtree invariant checks.
1304
1305config INTERVAL_TREE_TEST
1306        tristate "Interval tree test"
1307        depends on m && DEBUG_KERNEL
1308        help
1309          A benchmark measuring the performance of the interval tree library
1310
1311config PROVIDE_OHCI1394_DMA_INIT
1312        bool "Remote debugging over FireWire early on boot"
1313        depends on PCI && X86
1314        help
1315          If you want to debug problems which hang or crash the kernel early
1316          on boot and the crashing machine has a FireWire port, you can use
1317          this feature to remotely access the memory of the crashed machine
1318          over FireWire. This employs remote DMA as part of the OHCI1394
1319          specification which is now the standard for FireWire controllers.
1320
1321          With remote DMA, you can monitor the printk buffer remotely using
1322          firescope and access all memory below 4GB using fireproxy from gdb.
1323          Even controlling a kernel debugger is possible using remote DMA.
1324
1325          Usage:
1326
1327          If ohci1394_dma=early is used as boot parameter, it will initialize
1328          all OHCI1394 controllers which are found in the PCI config space.
1329
1330          As all changes to the FireWire bus such as enabling and disabling
1331          devices cause a bus reset and thereby disable remote DMA for all
1332          devices, be sure to have the cable plugged and FireWire enabled on
1333          the debugging host before booting the debug target for debugging.
1334
1335          This code (~1k) is freed after boot. By then, the firewire stack
1336          in charge of the OHCI-1394 controllers should be used instead.
1337
1338          See Documentation/debugging-via-ohci1394.txt for more information.
1339
1340config FIREWIRE_OHCI_REMOTE_DMA
1341        bool "Remote debugging over FireWire with firewire-ohci"
1342        depends on FIREWIRE_OHCI
1343        help
1344          This option lets you use the FireWire bus for remote debugging
1345          with help of the firewire-ohci driver. It enables unfiltered
1346          remote DMA in firewire-ohci.
1347          See Documentation/debugging-via-ohci1394.txt for more information.
1348
1349          If unsure, say N.
1350
1351config BUILD_DOCSRC
1352        bool "Build targets in Documentation/ tree"
1353        depends on HEADERS_CHECK
1354        help
1355          This option attempts to build objects from the source files in the
1356          kernel Documentation/ tree.
1357
1358          Say N if you are unsure.
1359
1360config DYNAMIC_DEBUG
1361        bool "Enable dynamic printk() support"
1362        default n
1363        depends on PRINTK
1364        depends on DEBUG_FS
1365        help
1366
1367          Compiles debug level messages into the kernel, which would not
1368          otherwise be available at runtime. These messages can then be
1369          enabled/disabled based on various levels of scope - per source file,
1370          function, module, format string, and line number. This mechanism
1371          implicitly compiles in all pr_debug() and dev_dbg() calls, which
1372          enlarges the kernel text size by about 2%.
1373
1374          If a source file is compiled with DEBUG flag set, any
1375          pr_debug() calls in it are enabled by default, but can be
1376          disabled at runtime as below.  Note that DEBUG flag is
1377          turned on by many CONFIG_*DEBUG* options.
1378
1379          Usage:
1380
1381          Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1382          which is contained in the 'debugfs' filesystem. Thus, the debugfs
1383          filesystem must first be mounted before making use of this feature.
1384          We refer the control file as: <debugfs>/dynamic_debug/control. This
1385          file contains a list of the debug statements that can be enabled. The
1386          format for each line of the file is:
1387
1388                filename:lineno [module]function flags format
1389
1390          filename : source file of the debug statement
1391          lineno : line number of the debug statement
1392          module : module that contains the debug statement
1393          function : function that contains the debug statement
1394          flags : '=p' means the line is turned 'on' for printing
1395          format : the format used for the debug statement
1396
1397          From a live system:
1398
1399                nullarbor:~ # cat <debugfs>/dynamic_debug/control
1400                # filename:lineno [module]function flags format
1401                fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1402                fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1403                fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
1404
1405          Example usage:
1406
1407                // enable the message at line 1603 of file svcsock.c
1408                nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1409                                                <debugfs>/dynamic_debug/control
1410
1411                // enable all the messages in file svcsock.c
1412                nullarbor:~ # echo -n 'file svcsock.c +p' >
1413                                                <debugfs>/dynamic_debug/control
1414
1415                // enable all the messages in the NFS server module
1416                nullarbor:~ # echo -n 'module nfsd +p' >
1417                                                <debugfs>/dynamic_debug/control
1418
1419                // enable all 12 messages in the function svc_process()
1420                nullarbor:~ # echo -n 'func svc_process +p' >
1421                                                <debugfs>/dynamic_debug/control
1422
1423                // disable all 12 messages in the function svc_process()
1424                nullarbor:~ # echo -n 'func svc_process -p' >
1425                                                <debugfs>/dynamic_debug/control
1426
1427          See Documentation/dynamic-debug-howto.txt for additional information.
1428
1429config DMA_API_DEBUG
1430        bool "Enable debugging of DMA-API usage"
1431        depends on HAVE_DMA_API_DEBUG
1432        help
1433          Enable this option to debug the use of the DMA API by device drivers.
1434          With this option you will be able to detect common bugs in device
1435          drivers like double-freeing of DMA mappings or freeing mappings that
1436          were never allocated.
1437          This option causes a performance degredation.  Use only if you want
1438          to debug device drivers. If unsure, say N.
1439
1440config ATOMIC64_SELFTEST
1441        bool "Perform an atomic64_t self-test at boot"
1442        help
1443          Enable this option to test the atomic64_t functions at boot.
1444
1445          If unsure, say N.
1446
1447config ASYNC_RAID6_TEST
1448        tristate "Self test for hardware accelerated raid6 recovery"
1449        depends on ASYNC_RAID6_RECOV
1450        select ASYNC_MEMCPY
1451        ---help---
1452          This is a one-shot self test that permutes through the
1453          recovery of all the possible two disk failure scenarios for a
1454          N-disk array.  Recovery is performed with the asynchronous
1455          raid6 recovery routines, and will optionally use an offload
1456          engine if one is available.
1457
1458          If unsure, say N.
1459
1460source "samples/Kconfig"
1461
1462source "lib/Kconfig.kgdb"
1463
1464source "lib/Kconfig.kmemcheck"
1465
1466config TEST_KSTRTOX
1467        tristate "Test kstrto*() family of functions at runtime"
1468
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