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 ENABLE_WARN_DEPRECATED
  13         bool "Enable __deprecated logic"
  14         default y
  15         help
  16           Enable the __deprecated logic in the kernel build.
  17           Disable this to suppress the "warning: 'foo' is deprecated
  18           (declared at kernel/power/somefile.c:1234)" messages.
  19
  20 config ENABLE_MUST_CHECK
  21         bool "Enable __must_check logic"
  22         default y
  23         help
  24           Enable the __must_check logic in the kernel build.  Disable this to
  25           suppress the "warning: ignoring return value of 'foo', declared with
  26           attribute warn_unused_result" messages.
  27
  28 config FRAME_WARN
  29         int "Warn for stack frames larger than (needs gcc 4.4)"
  30         range 0 8192
  31         default 1024 if !64BIT
  32         default 2048 if 64BIT
  33         help
  34           Tell gcc to warn at build time for stack frames larger than this.
  35           Setting this too low will cause a lot of warnings.
  36           Setting it to 0 disables the warning.
  37           Requires gcc 4.4
  38
  39 config MAGIC_SYSRQ
  40         bool "Magic SysRq key"
  41         depends on !UML
  42         help
  43           If you say Y here, you will have some control over the system even
  44           if the system crashes for example during kernel debugging (e.g., you
  45           will be able to flush the buffer cache to disk, reboot the system
  46           immediately or dump some status information). This is accomplished
  47           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  48           also works on a serial console (on PC hardware at least), if you
  49           send a BREAK and then within 5 seconds a command keypress. The
  50           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  51           unless you really know what this hack does.
  52
  53 config STRIP_ASM_SYMS
  54         bool "Strip assembler-generated symbols during link"
  55         default n
  56         help
  57           Strip internal assembler-generated symbols during a link (symbols
  58           that look like '.Lxxx') so they don't pollute the output of
  59           get_wchan() and suchlike.
  60
  61 config UNUSED_SYMBOLS
  62         bool "Enable unused/obsolete exported symbols"
  63         default y if X86
  64         help
  65           Unused but exported symbols make the kernel needlessly bigger.  For
  66           that reason most of these unused exports will soon be removed.  This
  67           option is provided temporarily to provide a transition period in case
  68           some external kernel module needs one of these symbols anyway. If you
  69           encounter such a case in your module, consider if you are actually
  70           using the right API.  (rationale: since nobody in the kernel is using
  71           this in a module, there is a pretty good chance it's actually the
  72           wrong interface to use).  If you really need the symbol, please send a
  73           mail to the linux kernel mailing list mentioning the symbol and why
  74           you really need it, and what the merge plan to the mainline kernel for
  75           your module is.
  76
  77 config DEBUG_FS
  78         bool "Debug Filesystem"
  79         help
  80           debugfs is a virtual file system that kernel developers use to put
  81           debugging files into.  Enable this option to be able to read and
  82           write to these files.
  83
  84           For detailed documentation on the debugfs API, see
  85           Documentation/DocBook/filesystems.
  86
  87           If unsure, say N.
  88
  89 config HEADERS_CHECK
  90         bool "Run 'make headers_check' when building vmlinux"
  91         depends on !UML
  92         help
  93           This option will extract the user-visible kernel headers whenever
  94           building the kernel, and will run basic sanity checks on them to
  95           ensure that exported files do not attempt to include files which
  96           were not exported, etc.
  97
  98           If you're making modifications to header files which are
  99           relevant for userspace, say 'Y', and check the headers
 100           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 101           your build tree), to make sure they're suitable.
 102
 103 config DEBUG_SECTION_MISMATCH
 104         bool "Enable full Section mismatch analysis"
 105         depends on UNDEFINED || (BLACKFIN)
 106         default y
 107         # This option is on purpose disabled for now.
 108         # It will be enabled when we are down to a reasonable number
 109         # of section mismatch warnings (< 10 for an allyesconfig build)
 110         help
 111           The section mismatch analysis checks if there are illegal
 112           references from one section to another section.
 113           Linux will during link or during runtime drop some sections
 114           and any use of code/data previously in these sections will
 115           most likely result in an oops.
 116           In the code functions and variables are annotated with
 117           __init, __devinit etc. (see full list in include/linux/init.h)
 118           which results in the code/data being placed in specific sections.
 119           The section mismatch analysis is always done after a full
 120           kernel build but enabling this option will in addition
 121           do the following:
 122           - Add the option -fno-inline-functions-called-once to gcc
 123             When inlining a function annotated __init in a non-init
 124             function we would lose the section information and thus
 125             the analysis would not catch the illegal reference.
 126             This option tells gcc to inline less but will also
 127             result in a larger kernel.
 128           - Run the section mismatch analysis for each module/built-in.o
 129             When we run the section mismatch analysis on vmlinux.o we
 130             lose valueble information about where the mismatch was
 131             introduced.
 132             Running the analysis for each module/built-in.o file
 133             will tell where the mismatch happens much closer to the
 134             source. The drawback is that we will report the same
 135             mismatch at least twice.
 136           - Enable verbose reporting from modpost to help solving
 137             the section mismatches reported.
 138
 139 config DEBUG_KERNEL
 140         bool "Kernel debugging"
 141         help
 142           Say Y here if you are developing drivers or trying to debug and
 143           identify kernel problems.
 144
 145 config DEBUG_SHIRQ
 146         bool "Debug shared IRQ handlers"
 147         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 148         help
 149           Enable this to generate a spurious interrupt as soon as a shared
 150           interrupt handler is registered, and just before one is deregistered.
 151           Drivers ought to be able to handle interrupts coming in at those
 152           points; some don't and need to be caught.
 153
 154 config LOCKUP_DETECTOR
 155         bool "Detect Hard and Soft Lockups"
 156         depends on DEBUG_KERNEL && !S390
 157         help
 158           Say Y here to enable the kernel to act as a watchdog to detect
 159           hard and soft lockups.
 160
 161           Softlockups are bugs that cause the kernel to loop in kernel
 162           mode for more than 60 seconds, without giving other tasks a
 163           chance to run.  The current stack trace is displayed upon
 164           detection and the system will stay locked up.
 165
 166           Hardlockups are bugs that cause the CPU to loop in kernel mode
 167           for more than 60 seconds, without letting other interrupts have a
 168           chance to run.  The current stack trace is displayed upon detection
 169           and the system will stay locked up.
 170
 171           The overhead should be minimal.  A periodic hrtimer runs to
 172           generate interrupts and kick the watchdog task every 10-12 seconds.
 173           An NMI is generated every 60 seconds or so to check for hardlockups.
 174
 175 config HARDLOCKUP_DETECTOR
 176         def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
 177                  !ARCH_HAS_NMI_WATCHDOG
 178
 179 config BOOTPARAM_SOFTLOCKUP_PANIC
 180         bool "Panic (Reboot) On Soft Lockups"
 181         depends on LOCKUP_DETECTOR
 182         help
 183           Say Y here to enable the kernel to panic on "soft lockups",
 184           which are bugs that cause the kernel to loop in kernel
 185           mode for more than 60 seconds, without giving other tasks a
 186           chance to run.
 187
 188           The panic can be used in combination with panic_timeout,
 189           to cause the system to reboot automatically after a
 190           lockup has been detected. This feature is useful for
 191           high-availability systems that have uptime guarantees and
 192           where a lockup must be resolved ASAP.
 193
 194           Say N if unsure.
 195
 196 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 197         int
 198         depends on LOCKUP_DETECTOR
 199         range 0 1
 200         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 201         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 202
 203 config DETECT_HUNG_TASK
 204         bool "Detect Hung Tasks"
 205         depends on DEBUG_KERNEL
 206         default DETECT_SOFTLOCKUP
 207         help
 208           Say Y here to enable the kernel to detect "hung tasks",
 209           which are bugs that cause the task to be stuck in
 210           uninterruptible "D" state indefinitiley.
 211
 212           When a hung task is detected, the kernel will print the
 213           current stack trace (which you should report), but the
 214           task will stay in uninterruptible state. If lockdep is
 215           enabled then all held locks will also be reported. This
 216           feature has negligible overhead.
 217
 218 config BOOTPARAM_HUNG_TASK_PANIC
 219         bool "Panic (Reboot) On Hung Tasks"
 220         depends on DETECT_HUNG_TASK
 221         help
 222           Say Y here to enable the kernel to panic on "hung tasks",
 223           which are bugs that cause the kernel to leave a task stuck
 224           in uninterruptible "D" state.
 225
 226           The panic can be used in combination with panic_timeout,
 227           to cause the system to reboot automatically after a
 228           hung task has been detected. This feature is useful for
 229           high-availability systems that have uptime guarantees and
 230           where a hung tasks must be resolved ASAP.
 231
 232           Say N if unsure.
 233
 234 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 235         int
 236         depends on DETECT_HUNG_TASK
 237         range 0 1
 238         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 239         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 240
 241 config SCHED_DEBUG
 242         bool "Collect scheduler debugging info"
 243         depends on DEBUG_KERNEL && PROC_FS
 244         default y
 245         help
 246           If you say Y here, the /proc/sched_debug file will be provided
 247           that can help debug the scheduler. The runtime overhead of this
 248           option is minimal.
 249
 250 config SCHEDSTATS
 251         bool "Collect scheduler statistics"
 252         depends on DEBUG_KERNEL && PROC_FS
 253         help
 254           If you say Y here, additional code will be inserted into the
 255           scheduler and related routines to collect statistics about
 256           scheduler behavior and provide them in /proc/schedstat.  These
 257           stats may be useful for both tuning and debugging the scheduler
 258           If you aren't debugging the scheduler or trying to tune a specific
 259           application, you can say N to avoid the very slight overhead
 260           this adds.
 261
 262 config TIMER_STATS
 263         bool "Collect kernel timers statistics"
 264         depends on DEBUG_KERNEL && PROC_FS
 265         help
 266           If you say Y here, additional code will be inserted into the
 267           timer routines to collect statistics about kernel timers being
 268           reprogrammed. The statistics can be read from /proc/timer_stats.
 269           The statistics collection is started by writing 1 to /proc/timer_stats,
 270           writing 0 stops it. This feature is useful to collect information
 271           about timer usage patterns in kernel and userspace. This feature
 272           is lightweight if enabled in the kernel config but not activated
 273           (it defaults to deactivated on bootup and will only be activated
 274           if some application like powertop activates it explicitly).
 275
 276 config DEBUG_OBJECTS
 277         bool "Debug object operations"
 278         depends on DEBUG_KERNEL
 279         help
 280           If you say Y here, additional code will be inserted into the
 281           kernel to track the life time of various objects and validate
 282           the operations on those objects.
 283
 284 config DEBUG_OBJECTS_SELFTEST
 285         bool "Debug objects selftest"
 286         depends on DEBUG_OBJECTS
 287         help
 288           This enables the selftest of the object debug code.
 289
 290 config DEBUG_OBJECTS_FREE
 291         bool "Debug objects in freed memory"
 292         depends on DEBUG_OBJECTS
 293         help
 294           This enables checks whether a k/v free operation frees an area
 295           which contains an object which has not been deactivated
 296           properly. This can make kmalloc/kfree-intensive workloads
 297           much slower.
 298
 299 config DEBUG_OBJECTS_TIMERS
 300         bool "Debug timer objects"
 301         depends on DEBUG_OBJECTS
 302         help
 303           If you say Y here, additional code will be inserted into the
 304           timer routines to track the life time of timer objects and
 305           validate the timer operations.
 306
 307 config DEBUG_OBJECTS_WORK
 308         bool "Debug work objects"
 309         depends on DEBUG_OBJECTS
 310         help
 311           If you say Y here, additional code will be inserted into the
 312           work queue routines to track the life time of work objects and
 313           validate the work operations.
 314
 315 config DEBUG_OBJECTS_RCU_HEAD
 316         bool "Debug RCU callbacks objects"
 317         depends on DEBUG_OBJECTS && PREEMPT
 318         help
 319           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 320
 321 config DEBUG_OBJECTS_PERCPU_COUNTER
 322         bool "Debug percpu counter objects"
 323         depends on DEBUG_OBJECTS
 324         help
 325           If you say Y here, additional code will be inserted into the
 326           percpu counter routines to track the life time of percpu counter
 327           objects and validate the percpu counter operations.
 328
 329 config DEBUG_OBJECTS_ENABLE_DEFAULT
 330         int "debug_objects bootup default value (0-1)"
 331         range 0 1
 332         default "1"
 333         depends on DEBUG_OBJECTS
 334         help
 335           Debug objects boot parameter default value
 336
 337 config DEBUG_SLAB
 338         bool "Debug slab memory allocations"
 339         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 340         help
 341           Say Y here to have the kernel do limited verification on memory
 342           allocation as well as poisoning memory on free to catch use of freed
 343           memory. This can make kmalloc/kfree-intensive workloads much slower.
 344
 345 config DEBUG_SLAB_LEAK
 346         bool "Memory leak debugging"
 347         depends on DEBUG_SLAB
 348
 349 config SLUB_DEBUG_ON
 350         bool "SLUB debugging on by default"
 351         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 352         default n
 353         help
 354           Boot with debugging on by default. SLUB boots by default with
 355           the runtime debug capabilities switched off. Enabling this is
 356           equivalent to specifying the "slub_debug" parameter on boot.
 357           There is no support for more fine grained debug control like
 358           possible with slub_debug=xxx. SLUB debugging may be switched
 359           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 360           "slub_debug=-".
 361
 362 config SLUB_STATS
 363         default n
 364         bool "Enable SLUB performance statistics"
 365         depends on SLUB && SYSFS
 366         help
 367           SLUB statistics are useful to debug SLUBs allocation behavior in
 368           order find ways to optimize the allocator. This should never be
 369           enabled for production use since keeping statistics slows down
 370           the allocator by a few percentage points. The slabinfo command
 371           supports the determination of the most active slabs to figure
 372           out which slabs are relevant to a particular load.
 373           Try running: slabinfo -DA
 374
 375 config DEBUG_KMEMLEAK
 376         bool "Kernel memory leak detector"
 377         depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
 378                 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
 379
 380         select DEBUG_FS if SYSFS
 381         select STACKTRACE if STACKTRACE_SUPPORT
 382         select KALLSYMS
 383         select CRC32
 384         help
 385           Say Y here if you want to enable the memory leak
 386           detector. The memory allocation/freeing is traced in a way
 387           similar to the Boehm's conservative garbage collector, the
 388           difference being that the orphan objects are not freed but
 389           only shown in /sys/kernel/debug/kmemleak. Enabling this
 390           feature will introduce an overhead to memory
 391           allocations. See Documentation/kmemleak.txt for more
 392           details.
 393
 394           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 395           of finding leaks due to the slab objects poisoning.
 396
 397           In order to access the kmemleak file, debugfs needs to be
 398           mounted (usually at /sys/kernel/debug).
 399
 400 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 401         int "Maximum kmemleak early log entries"
 402         depends on DEBUG_KMEMLEAK
 403         range 200 40000
 404         default 400
 405         help
 406           Kmemleak must track all the memory allocations to avoid
 407           reporting false positives. Since memory may be allocated or
 408           freed before kmemleak is initialised, an early log buffer is
 409           used to store these actions. If kmemleak reports "early log
 410           buffer exceeded", please increase this value.
 411
 412 config DEBUG_KMEMLEAK_TEST
 413         tristate "Simple test for the kernel memory leak detector"
 414         depends on DEBUG_KMEMLEAK
 415         help
 416           Say Y or M here to build a test for the kernel memory leak
 417           detector. This option enables a module that explicitly leaks
 418           memory.
 419
 420           If unsure, say N.
 421
 422 config DEBUG_KMEMLEAK_DEFAULT_OFF
 423         bool "Default kmemleak to off"
 424         depends on DEBUG_KMEMLEAK
 425         help
 426           Say Y here to disable kmemleak by default. It can then be enabled
 427           on the command line via kmemleak=on.
 428
 429 config DEBUG_PREEMPT
 430         bool "Debug preemptible kernel"
 431         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 432         default y
 433         help
 434           If you say Y here then the kernel will use a debug variant of the
 435           commonly used smp_processor_id() function and will print warnings
 436           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 437           will detect preemption count underflows.
 438
 439 config DEBUG_RT_MUTEXES
 440         bool "RT Mutex debugging, deadlock detection"
 441         depends on DEBUG_KERNEL && RT_MUTEXES
 442         help
 443          This allows rt mutex semantics violations and rt mutex related
 444          deadlocks (lockups) to be detected and reported automatically.
 445
 446 config DEBUG_PI_LIST
 447         bool
 448         default y
 449         depends on DEBUG_RT_MUTEXES
 450
 451 config RT_MUTEX_TESTER
 452         bool "Built-in scriptable tester for rt-mutexes"
 453         depends on DEBUG_KERNEL && RT_MUTEXES
 454         help
 455           This option enables a rt-mutex tester.
 456
 457 config DEBUG_SPINLOCK
 458         bool "Spinlock and rw-lock debugging: basic checks"
 459         depends on DEBUG_KERNEL
 460         help
 461           Say Y here and build SMP to catch missing spinlock initialization
 462           and certain other kinds of spinlock errors commonly made.  This is
 463           best used in conjunction with the NMI watchdog so that spinlock
 464           deadlocks are also debuggable.
 465
 466 config DEBUG_MUTEXES
 467         bool "Mutex debugging: basic checks"
 468         depends on DEBUG_KERNEL
 469         help
 470          This feature allows mutex semantics violations to be detected and
 471          reported.
 472
 473 config DEBUG_LOCK_ALLOC
 474         bool "Lock debugging: detect incorrect freeing of live locks"
 475         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 476         select DEBUG_SPINLOCK
 477         select DEBUG_MUTEXES
 478         select LOCKDEP
 479         help
 480          This feature will check whether any held lock (spinlock, rwlock,
 481          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 482          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 483          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 484          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 485          held during task exit.
 486
 487 config PROVE_LOCKING
 488         bool "Lock debugging: prove locking correctness"
 489         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 490         select LOCKDEP
 491         select DEBUG_SPINLOCK
 492         select DEBUG_MUTEXES
 493         select DEBUG_LOCK_ALLOC
 494         select TRACE_IRQFLAGS
 495         default n
 496         help
 497          This feature enables the kernel to prove that all locking
 498          that occurs in the kernel runtime is mathematically
 499          correct: that under no circumstance could an arbitrary (and
 500          not yet triggered) combination of observed locking
 501          sequences (on an arbitrary number of CPUs, running an
 502          arbitrary number of tasks and interrupt contexts) cause a
 503          deadlock.
 504
 505          In short, this feature enables the kernel to report locking
 506          related deadlocks before they actually occur.
 507
 508          The proof does not depend on how hard and complex a
 509          deadlock scenario would be to trigger: how many
 510          participant CPUs, tasks and irq-contexts would be needed
 511          for it to trigger. The proof also does not depend on
 512          timing: if a race and a resulting deadlock is possible
 513          theoretically (no matter how unlikely the race scenario
 514          is), it will be proven so and will immediately be
 515          reported by the kernel (once the event is observed that
 516          makes the deadlock theoretically possible).
 517
 518          If a deadlock is impossible (i.e. the locking rules, as
 519          observed by the kernel, are mathematically correct), the
 520          kernel reports nothing.
 521
 522          NOTE: this feature can also be enabled for rwlocks, mutexes
 523          and rwsems - in which case all dependencies between these
 524          different locking variants are observed and mapped too, and
 525          the proof of observed correctness is also maintained for an
 526          arbitrary combination of these separate locking variants.
 527
 528          For more details, see Documentation/lockdep-design.txt.
 529
 530 config PROVE_RCU
 531         bool "RCU debugging: prove RCU correctness"
 532         depends on PROVE_LOCKING
 533         default n
 534         help
 535          This feature enables lockdep extensions that check for correct
 536          use of RCU APIs.  This is currently under development.  Say Y
 537          if you want to debug RCU usage or help work on the PROVE_RCU
 538          feature.
 539
 540          Say N if you are unsure.
 541
 542 config PROVE_RCU_REPEATEDLY
 543         bool "RCU debugging: don't disable PROVE_RCU on first splat"
 544         depends on PROVE_RCU
 545         default n
 546         help
 547          By itself, PROVE_RCU will disable checking upon issuing the
 548          first warning (or "splat").  This feature prevents such
 549          disabling, allowing multiple RCU-lockdep warnings to be printed
 550          on a single reboot.
 551
 552          Say Y to allow multiple RCU-lockdep warnings per boot.
 553
 554          Say N if you are unsure.
 555
 556 config SPARSE_RCU_POINTER
 557         bool "RCU debugging: sparse-based checks for pointer usage"
 558         default n
 559         help
 560          This feature enables the __rcu sparse annotation for
 561          RCU-protected pointers.  This annotation will cause sparse
 562          to flag any non-RCU used of annotated pointers.  This can be
 563          helpful when debugging RCU usage.  Please note that this feature
 564          is not intended to enforce code cleanliness; it is instead merely
 565          a debugging aid.
 566
 567          Say Y to make sparse flag questionable use of RCU-protected pointers
 568
 569          Say N if you are unsure.
 570
 571 config LOCKDEP
 572         bool
 573         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 574         select STACKTRACE
 575         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 576         select KALLSYMS
 577         select KALLSYMS_ALL
 578
 579 config LOCK_STAT
 580         bool "Lock usage statistics"
 581         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 582         select LOCKDEP
 583         select DEBUG_SPINLOCK
 584         select DEBUG_MUTEXES
 585         select DEBUG_LOCK_ALLOC
 586         default n
 587         help
 588          This feature enables tracking lock contention points
 589
 590          For more details, see Documentation/lockstat.txt
 591
 592          This also enables lock events required by "perf lock",
 593          subcommand of perf.
 594          If you want to use "perf lock", you also need to turn on
 595          CONFIG_EVENT_TRACING.
 596
 597          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 598          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 599
 600 config DEBUG_LOCKDEP
 601         bool "Lock dependency engine debugging"
 602         depends on DEBUG_KERNEL && LOCKDEP
 603         help
 604           If you say Y here, the lock dependency engine will do
 605           additional runtime checks to debug itself, at the price
 606           of more runtime overhead.
 607
 608 config TRACE_IRQFLAGS
 609         bool
 610         help
 611           Enables hooks to interrupt enabling and disabling for
 612           either tracing or lock debugging.
 613
 614 config DEBUG_SPINLOCK_SLEEP
 615         bool "Spinlock debugging: sleep-inside-spinlock checking"
 616         depends on DEBUG_KERNEL
 617         help
 618           If you say Y here, various routines which may sleep will become very
 619           noisy if they are called with a spinlock held.
 620
 621 config DEBUG_LOCKING_API_SELFTESTS
 622         bool "Locking API boot-time self-tests"
 623         depends on DEBUG_KERNEL
 624         help
 625           Say Y here if you want the kernel to run a short self-test during
 626           bootup. The self-test checks whether common types of locking bugs
 627           are detected by debugging mechanisms or not. (if you disable
 628           lock debugging then those bugs wont be detected of course.)
 629           The following locking APIs are covered: spinlocks, rwlocks,
 630           mutexes and rwsems.
 631
 632 config STACKTRACE
 633         bool
 634         depends on STACKTRACE_SUPPORT
 635
 636 config DEBUG_KOBJECT
 637         bool "kobject debugging"
 638         depends on DEBUG_KERNEL
 639         help
 640           If you say Y here, some extra kobject debugging messages will be sent
 641           to the syslog.
 642
 643 config DEBUG_HIGHMEM
 644         bool "Highmem debugging"
 645         depends on DEBUG_KERNEL && HIGHMEM
 646         help
 647           This options enables addition error checking for high memory systems.
 648           Disable for production systems.
 649
 650 config DEBUG_BUGVERBOSE
 651         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
 652         depends on BUG
 653         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 654                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 655         default y
 656         help
 657           Say Y here to make BUG() panics output the file name and line number
 658           of the BUG call as well as the EIP and oops trace.  This aids
 659           debugging but costs about 70-100K of memory.
 660
 661 config DEBUG_INFO
 662         bool "Compile the kernel with debug info"
 663         depends on DEBUG_KERNEL
 664         help
 665           If you say Y here the resulting kernel image will include
 666           debugging info resulting in a larger kernel image.
 667           This adds debug symbols to the kernel and modules (gcc -g), and
 668           is needed if you intend to use kernel crashdump or binary object
 669           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 670           Say Y here only if you plan to debug the kernel.
 671
 672           If unsure, say N.
 673
 674 config DEBUG_INFO_REDUCED
 675         bool "Reduce debugging information"
 676         depends on DEBUG_INFO
 677         help
 678           If you say Y here gcc is instructed to generate less debugging
 679           information for structure types. This means that tools that
 680           need full debugging information (like kgdb or systemtap) won't
 681           be happy. But if you merely need debugging information to
 682           resolve line numbers there is no loss. Advantage is that
 683           build directory object sizes shrink dramatically over a full
 684           DEBUG_INFO build and compile times are reduced too.
 685           Only works with newer gcc versions.
 686
 687 config DEBUG_VM
 688         bool "Debug VM"
 689         depends on DEBUG_KERNEL
 690         help
 691           Enable this to turn on extended checks in the virtual-memory system
 692           that may impact performance.
 693
 694           If unsure, say N.
 695
 696 config DEBUG_VIRTUAL
 697         bool "Debug VM translations"
 698         depends on DEBUG_KERNEL && X86
 699         help
 700           Enable some costly sanity checks in virtual to page code. This can
 701           catch mistakes with virt_to_page() and friends.
 702
 703           If unsure, say N.
 704
 705 config DEBUG_NOMMU_REGIONS
 706         bool "Debug the global anon/private NOMMU mapping region tree"
 707         depends on DEBUG_KERNEL && !MMU
 708         help
 709           This option causes the global tree of anonymous and private mapping
 710           regions to be regularly checked for invalid topology.
 711
 712 config DEBUG_WRITECOUNT
 713         bool "Debug filesystem writers count"
 714         depends on DEBUG_KERNEL
 715         help
 716           Enable this to catch wrong use of the writers count in struct
 717           vfsmount.  This will increase the size of each file struct by
 718           32 bits.
 719
 720           If unsure, say N.
 721
 722 config DEBUG_MEMORY_INIT
 723         bool "Debug memory initialisation" if EXPERT
 724         default !EXPERT
 725         help
 726           Enable this for additional checks during memory initialisation.
 727           The sanity checks verify aspects of the VM such as the memory model
 728           and other information provided by the architecture. Verbose
 729           information will be printed at KERN_DEBUG loglevel depending
 730           on the mminit_loglevel= command-line option.
 731
 732           If unsure, say Y
 733
 734 config DEBUG_LIST
 735         bool "Debug linked list manipulation"
 736         depends on DEBUG_KERNEL
 737         help
 738           Enable this to turn on extended checks in the linked-list
 739           walking routines.
 740
 741           If unsure, say N.
 742
 743 config TEST_LIST_SORT
 744         bool "Linked list sorting test"
 745         depends on DEBUG_KERNEL
 746         help
 747           Enable this to turn on 'list_sort()' function test. This test is
 748           executed only once during system boot, so affects only boot time.
 749
 750           If unsure, say N.
 751
 752 config DEBUG_SG
 753         bool "Debug SG table operations"
 754         depends on DEBUG_KERNEL
 755         help
 756           Enable this to turn on checks on scatter-gather tables. This can
 757           help find problems with drivers that do not properly initialize
 758           their sg tables.
 759
 760           If unsure, say N.
 761
 762 config DEBUG_NOTIFIERS
 763         bool "Debug notifier call chains"
 764         depends on DEBUG_KERNEL
 765         help
 766           Enable this to turn on sanity checking for notifier call chains.
 767           This is most useful for kernel developers to make sure that
 768           modules properly unregister themselves from notifier chains.
 769           This is a relatively cheap check but if you care about maximum
 770           performance, say N.
 771
 772 config DEBUG_CREDENTIALS
 773         bool "Debug credential management"
 774         depends on DEBUG_KERNEL
 775         help
 776           Enable this to turn on some debug checking for credential
 777           management.  The additional code keeps track of the number of
 778           pointers from task_structs to any given cred struct, and checks to
 779           see that this number never exceeds the usage count of the cred
 780           struct.
 781
 782           Furthermore, if SELinux is enabled, this also checks that the
 783           security pointer in the cred struct is never seen to be invalid.
 784
 785           If unsure, say N.
 786
 787 #
 788 # Select this config option from the architecture Kconfig, if it
 789 # it is preferred to always offer frame pointers as a config
 790 # option on the architecture (regardless of KERNEL_DEBUG):
 791 #
 792 config ARCH_WANT_FRAME_POINTERS
 793         bool
 794         help
 795
 796 config FRAME_POINTER
 797         bool "Compile the kernel with frame pointers"
 798         depends on DEBUG_KERNEL && \
 799                 (CRIS || M68K || FRV || UML || \
 800                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 801                 ARCH_WANT_FRAME_POINTERS
 802         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 803         help
 804           If you say Y here the resulting kernel image will be slightly
 805           larger and slower, but it gives very useful debugging information
 806           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 807
 808 config BOOT_PRINTK_DELAY
 809         bool "Delay each boot printk message by N milliseconds"
 810         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 811         help
 812           This build option allows you to read kernel boot messages
 813           by inserting a short delay after each one.  The delay is
 814           specified in milliseconds on the kernel command line,
 815           using "boot_delay=N".
 816
 817           It is likely that you would also need to use "lpj=M" to preset
 818           the "loops per jiffie" value.
 819           See a previous boot log for the "lpj" value to use for your
 820           system, and then set "lpj=M" before setting "boot_delay=N".
 821           NOTE:  Using this option may adversely affect SMP systems.
 822           I.e., processors other than the first one may not boot up.
 823           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 824           what it believes to be lockup conditions.
 825
 826 config RCU_TORTURE_TEST
 827         tristate "torture tests for RCU"
 828         depends on DEBUG_KERNEL
 829         default n
 830         help
 831           This option provides a kernel module that runs torture tests
 832           on the RCU infrastructure.  The kernel module may be built
 833           after the fact on the running kernel to be tested, if desired.
 834
 835           Say Y here if you want RCU torture tests to be built into
 836           the kernel.
 837           Say M if you want the RCU torture tests to build as a module.
 838           Say N if you are unsure.
 839
 840 config RCU_TORTURE_TEST_RUNNABLE
 841         bool "torture tests for RCU runnable by default"
 842         depends on RCU_TORTURE_TEST = y
 843         default n
 844         help
 845           This option provides a way to build the RCU torture tests
 846           directly into the kernel without them starting up at boot
 847           time.  You can use /proc/sys/kernel/rcutorture_runnable
 848           to manually override this setting.  This /proc file is
 849           available only when the RCU torture tests have been built
 850           into the kernel.
 851
 852           Say Y here if you want the RCU torture tests to start during
 853           boot (you probably don't).
 854           Say N here if you want the RCU torture tests to start only
 855           after being manually enabled via /proc.
 856
 857 config RCU_CPU_STALL_DETECTOR
 858         bool "Check for stalled CPUs delaying RCU grace periods"
 859         depends on TREE_RCU || TREE_PREEMPT_RCU
 860         default y
 861         help
 862           This option causes RCU to printk information on which
 863           CPUs are delaying the current grace period, but only when
 864           the grace period extends for excessive time periods.
 865
 866           Say N if you want to disable such checks.
 867
 868           Say Y if you are unsure.
 869
 870 config RCU_CPU_STALL_TIMEOUT
 871         int "RCU CPU stall timeout in seconds"
 872         depends on RCU_CPU_STALL_DETECTOR
 873         range 3 300
 874         default 60
 875         help
 876           If a given RCU grace period extends more than the specified
 877           number of seconds, a CPU stall warning is printed.  If the
 878           RCU grace period persists, additional CPU stall warnings are
 879           printed at more widely spaced intervals.
 880
 881 config RCU_CPU_STALL_DETECTOR_RUNNABLE
 882         bool "RCU CPU stall checking starts automatically at boot"
 883         depends on RCU_CPU_STALL_DETECTOR
 884         default y
 885         help
 886           If set, start checking for RCU CPU stalls immediately on
 887           boot.  Otherwise, RCU CPU stall checking must be manually
 888           enabled.
 889
 890           Say Y if you are unsure.
 891
 892           Say N if you wish to suppress RCU CPU stall checking during boot.
 893
 894 config RCU_CPU_STALL_VERBOSE
 895         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 896         depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
 897         default y
 898         help
 899           This option causes RCU to printk detailed per-task information
 900           for any tasks that are stalling the current RCU grace period.
 901
 902           Say N if you are unsure.
 903
 904           Say Y if you want to enable such checks.
 905
 906 config KPROBES_SANITY_TEST
 907         bool "Kprobes sanity tests"
 908         depends on DEBUG_KERNEL
 909         depends on KPROBES
 910         default n
 911         help
 912           This option provides for testing basic kprobes functionality on
 913           boot. A sample kprobe, jprobe and kretprobe are inserted and
 914           verified for functionality.
 915
 916           Say N if you are unsure.
 917
 918 config BACKTRACE_SELF_TEST
 919         tristate "Self test for the backtrace code"
 920         depends on DEBUG_KERNEL
 921         default n
 922         help
 923           This option provides a kernel module that can be used to test
 924           the kernel stack backtrace code. This option is not useful
 925           for distributions or general kernels, but only for kernel
 926           developers working on architecture code.
 927
 928           Note that if you want to also test saved backtraces, you will
 929           have to enable STACKTRACE as well.
 930
 931           Say N if you are unsure.
 932
 933 config DEBUG_BLOCK_EXT_DEVT
 934         bool "Force extended block device numbers and spread them"
 935         depends on DEBUG_KERNEL
 936         depends on BLOCK
 937         default n
 938         help
 939           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 940           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 941           YOU ARE DOING.  Distros, please enable this and fix whatever
 942           is broken.
 943
 944           Conventionally, block device numbers are allocated from
 945           predetermined contiguous area.  However, extended block area
 946           may introduce non-contiguous block device numbers.  This
 947           option forces most block device numbers to be allocated from
 948           the extended space and spreads them to discover kernel or
 949           userland code paths which assume predetermined contiguous
 950           device number allocation.
 951
 952           Note that turning on this debug option shuffles all the
 953           device numbers for all IDE and SCSI devices including libata
 954           ones, so root partition specified using device number
 955           directly (via rdev or root=MAJ:MIN) won't work anymore.
 956           Textual device names (root=/dev/sdXn) will continue to work.
 957
 958           Say N if you are unsure.
 959
 960 config DEBUG_FORCE_WEAK_PER_CPU
 961         bool "Force weak per-cpu definitions"
 962         depends on DEBUG_KERNEL
 963         help
 964           s390 and alpha require percpu variables in modules to be
 965           defined weak to work around addressing range issue which
 966           puts the following two restrictions on percpu variable
 967           definitions.
 968
 969           1. percpu symbols must be unique whether static or not
 970           2. percpu variables can't be defined inside a function
 971
 972           To ensure that generic code follows the above rules, this
 973           option forces all percpu variables to be defined as weak.
 974
 975 config LKDTM
 976         tristate "Linux Kernel Dump Test Tool Module"
 977         depends on DEBUG_FS
 978         depends on BLOCK
 979         default n
 980         help
 981         This module enables testing of the different dumping mechanisms by
 982         inducing system failures at predefined crash points.
 983         If you don't need it: say N
 984         Choose M here to compile this code as a module. The module will be
 985         called lkdtm.
 986
 987         Documentation on how to use the module can be found in
 988         Documentation/fault-injection/provoke-crashes.txt
 989
 990 config CPU_NOTIFIER_ERROR_INJECT
 991         tristate "CPU notifier error injection module"
 992         depends on HOTPLUG_CPU && DEBUG_KERNEL
 993         help
 994           This option provides a kernel module that can be used to test
 995           the error handling of the cpu notifiers
 996
 997           To compile this code as a module, choose M here: the module will
 998           be called cpu-notifier-error-inject.
 999
1000           If unsure, say N.
1001
1002 config FAULT_INJECTION
1003         bool "Fault-injection framework"
1004         depends on DEBUG_KERNEL
1005         help
1006           Provide fault-injection framework.
1007           For more details, see Documentation/fault-injection/.
1008
1009 config FAILSLAB
1010         bool "Fault-injection capability for kmalloc"
1011         depends on FAULT_INJECTION
1012         depends on SLAB || SLUB
1013         help
1014           Provide fault-injection capability for kmalloc.
1015
1016 config FAIL_PAGE_ALLOC
1017         bool "Fault-injection capabilitiy for alloc_pages()"
1018         depends on FAULT_INJECTION
1019         help
1020           Provide fault-injection capability for alloc_pages().
1021
1022 config FAIL_MAKE_REQUEST
1023         bool "Fault-injection capability for disk IO"
1024         depends on FAULT_INJECTION && BLOCK
1025         help
1026           Provide fault-injection capability for disk IO.
1027
1028 config FAIL_IO_TIMEOUT
1029         bool "Fault-injection capability for faking disk interrupts"
1030         depends on FAULT_INJECTION && BLOCK
1031         help
1032           Provide fault-injection capability on end IO handling. This
1033           will make the block layer "forget" an interrupt as configured,
1034           thus exercising the error handling.
1035
1036           Only works with drivers that use the generic timeout handling,
1037           for others it wont do anything.
1038
1039 config FAULT_INJECTION_DEBUG_FS
1040         bool "Debugfs entries for fault-injection capabilities"
1041         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1042         help
1043           Enable configuration of fault-injection capabilities via debugfs.
1044
1045 config FAULT_INJECTION_STACKTRACE_FILTER
1046         bool "stacktrace filter for fault-injection capabilities"
1047         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1048         depends on !X86_64
1049         select STACKTRACE
1050         select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
1051         help
1052           Provide stacktrace filter for fault-injection capabilities
1053
1054 config LATENCYTOP
1055         bool "Latency measuring infrastructure"
1056         depends on HAVE_LATENCYTOP_SUPPORT
1057         depends on DEBUG_KERNEL
1058         depends on STACKTRACE_SUPPORT
1059         depends on PROC_FS
1060         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
1061         select KALLSYMS
1062         select KALLSYMS_ALL
1063         select STACKTRACE
1064         select SCHEDSTATS
1065         select SCHED_DEBUG
1066         help
1067           Enable this option if you want to use the LatencyTOP tool
1068           to find out which userspace is blocking on what kernel operations.
1069
1070 config SYSCTL_SYSCALL_CHECK
1071         bool "Sysctl checks"
1072         depends on SYSCTL
1073         ---help---
1074           sys_sysctl uses binary paths that have been found challenging
1075           to properly maintain and use. This enables checks that help
1076           you to keep things correct.
1077
1078 source mm/Kconfig.debug
1079 source kernel/trace/Kconfig
1080
1081 config PROVIDE_OHCI1394_DMA_INIT
1082         bool "Remote debugging over FireWire early on boot"
1083         depends on PCI && X86
1084         help
1085           If you want to debug problems which hang or crash the kernel early
1086           on boot and the crashing machine has a FireWire port, you can use
1087           this feature to remotely access the memory of the crashed machine
1088           over FireWire. This employs remote DMA as part of the OHCI1394
1089           specification which is now the standard for FireWire controllers.
1090
1091           With remote DMA, you can monitor the printk buffer remotely using
1092           firescope and access all memory below 4GB using fireproxy from gdb.
1093           Even controlling a kernel debugger is possible using remote DMA.
1094
1095           Usage:
1096
1097           If ohci1394_dma=early is used as boot parameter, it will initialize
1098           all OHCI1394 controllers which are found in the PCI config space.
1099
1100           As all changes to the FireWire bus such as enabling and disabling
1101           devices cause a bus reset and thereby disable remote DMA for all
1102           devices, be sure to have the cable plugged and FireWire enabled on
1103           the debugging host before booting the debug target for debugging.
1104
1105           This code (~1k) is freed after boot. By then, the firewire stack
1106           in charge of the OHCI-1394 controllers should be used instead.
1107
1108           See Documentation/debugging-via-ohci1394.txt for more information.
1109
1110 config FIREWIRE_OHCI_REMOTE_DMA
1111         bool "Remote debugging over FireWire with firewire-ohci"
1112         depends on FIREWIRE_OHCI
1113         help
1114           This option lets you use the FireWire bus for remote debugging
1115           with help of the firewire-ohci driver. It enables unfiltered
1116           remote DMA in firewire-ohci.
1117           See Documentation/debugging-via-ohci1394.txt for more information.
1118
1119           If unsure, say N.
1120
1121 config BUILD_DOCSRC
1122         bool "Build targets in Documentation/ tree"
1123         depends on HEADERS_CHECK
1124         help
1125           This option attempts to build objects from the source files in the
1126           kernel Documentation/ tree.
1127
1128           Say N if you are unsure.
1129
1130 config DYNAMIC_DEBUG
1131         bool "Enable dynamic printk() support"
1132         default n
1133         depends on PRINTK
1134         depends on DEBUG_FS
1135         help
1136
1137           Compiles debug level messages into the kernel, which would not
1138           otherwise be available at runtime. These messages can then be
1139           enabled/disabled based on various levels of scope - per source file,
1140           function, module, format string, and line number. This mechanism
1141           implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1142           this compile option is a larger kernel text size of about 2%.
1143
1144           Usage:
1145
1146           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1147           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1148           filesystem must first be mounted before making use of this feature.
1149           We refer the control file as: <debugfs>/dynamic_debug/control. This
1150           file contains a list of the debug statements that can be enabled. The
1151           format for each line of the file is:
1152
1153                 filename:lineno [module]function flags format
1154
1155           filename : source file of the debug statement
1156           lineno : line number of the debug statement
1157           module : module that contains the debug statement
1158           function : function that contains the debug statement
1159           flags : 'p' means the line is turned 'on' for printing
1160           format : the format used for the debug statement
1161
1162           From a live system:
1163
1164                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1165                 # filename:lineno [module]function flags format
1166                 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1167                 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1168                 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1169
1170           Example usage:
1171
1172                 // enable the message at line 1603 of file svcsock.c
1173                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1174                                                 <debugfs>/dynamic_debug/control
1175
1176                 // enable all the messages in file svcsock.c
1177                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1178                                                 <debugfs>/dynamic_debug/control
1179
1180                 // enable all the messages in the NFS server module
1181                 nullarbor:~ # echo -n 'module nfsd +p' >
1182                                                 <debugfs>/dynamic_debug/control
1183
1184                 // enable all 12 messages in the function svc_process()
1185                 nullarbor:~ # echo -n 'func svc_process +p' >
1186                                                 <debugfs>/dynamic_debug/control
1187
1188                 // disable all 12 messages in the function svc_process()
1189                 nullarbor:~ # echo -n 'func svc_process -p' >
1190                                                 <debugfs>/dynamic_debug/control
1191
1192           See Documentation/dynamic-debug-howto.txt for additional information.
1193
1194 config DMA_API_DEBUG
1195         bool "Enable debugging of DMA-API usage"
1196         depends on HAVE_DMA_API_DEBUG
1197         help
1198           Enable this option to debug the use of the DMA API by device drivers.
1199           With this option you will be able to detect common bugs in device
1200           drivers like double-freeing of DMA mappings or freeing mappings that
1201           were never allocated.
1202           This option causes a performance degredation.  Use only if you want
1203           to debug device drivers. If unsure, say N.
1204
1205 config ATOMIC64_SELFTEST
1206         bool "Perform an atomic64_t self-test at boot"
1207         help
1208           Enable this option to test the atomic64_t functions at boot.
1209
1210           If unsure, say N.
1211
1212 config ASYNC_RAID6_TEST
1213         tristate "Self test for hardware accelerated raid6 recovery"
1214         depends on ASYNC_RAID6_RECOV
1215         select ASYNC_MEMCPY
1216         ---help---
1217           This is a one-shot self test that permutes through the
1218           recovery of all the possible two disk failure scenarios for a
1219           N-disk array.  Recovery is performed with the asynchronous
1220           raid6 recovery routines, and will optionally use an offload
1221           engine if one is available.
1222
1223           If unsure, say N.
1224
1225 source "samples/Kconfig"
1226
1227 source "lib/Kconfig.kgdb"
1228
1229 source "lib/Kconfig.kmemcheck"