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