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
 178 config BOOTPARAM_SOFTLOCKUP_PANIC
 179         bool "Panic (Reboot) On Soft Lockups"
 180         depends on LOCKUP_DETECTOR
 181         help
 182           Say Y here to enable the kernel to panic on "soft lockups",
 183           which are bugs that cause the kernel to loop in kernel
 184           mode for more than 60 seconds, without giving other tasks a
 185           chance to run.
 186
 187           The panic can be used in combination with panic_timeout,
 188           to cause the system to reboot automatically after a
 189           lockup has been detected. This feature is useful for
 190           high-availability systems that have uptime guarantees and
 191           where a lockup must be resolved ASAP.
 192
 193           Say N if unsure.
 194
 195 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 196         int
 197         depends on LOCKUP_DETECTOR
 198         range 0 1
 199         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 200         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 201
 202 config DETECT_HUNG_TASK
 203         bool "Detect Hung Tasks"
 204         depends on DEBUG_KERNEL
 205         default DETECT_SOFTLOCKUP
 206         help
 207           Say Y here to enable the kernel to detect "hung tasks",
 208           which are bugs that cause the task to be stuck in
 209           uninterruptible "D" state indefinitiley.
 210
 211           When a hung task is detected, the kernel will print the
 212           current stack trace (which you should report), but the
 213           task will stay in uninterruptible state. If lockdep is
 214           enabled then all held locks will also be reported. This
 215           feature has negligible overhead.
 216
 217 config BOOTPARAM_HUNG_TASK_PANIC
 218         bool "Panic (Reboot) On Hung Tasks"
 219         depends on DETECT_HUNG_TASK
 220         help
 221           Say Y here to enable the kernel to panic on "hung tasks",
 222           which are bugs that cause the kernel to leave a task stuck
 223           in uninterruptible "D" state.
 224
 225           The panic can be used in combination with panic_timeout,
 226           to cause the system to reboot automatically after a
 227           hung task has been detected. This feature is useful for
 228           high-availability systems that have uptime guarantees and
 229           where a hung tasks must be resolved ASAP.
 230
 231           Say N if unsure.
 232
 233 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 234         int
 235         depends on DETECT_HUNG_TASK
 236         range 0 1
 237         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 238         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 239
 240 config SCHED_DEBUG
 241         bool "Collect scheduler debugging info"
 242         depends on DEBUG_KERNEL && PROC_FS
 243         default y
 244         help
 245           If you say Y here, the /proc/sched_debug file will be provided
 246           that can help debug the scheduler. The runtime overhead of this
 247           option is minimal.
 248
 249 config SCHEDSTATS
 250         bool "Collect scheduler statistics"
 251         depends on DEBUG_KERNEL && PROC_FS
 252         help
 253           If you say Y here, additional code will be inserted into the
 254           scheduler and related routines to collect statistics about
 255           scheduler behavior and provide them in /proc/schedstat.  These
 256           stats may be useful for both tuning and debugging the scheduler
 257           If you aren't debugging the scheduler or trying to tune a specific
 258           application, you can say N to avoid the very slight overhead
 259           this adds.
 260
 261 config TIMER_STATS
 262         bool "Collect kernel timers statistics"
 263         depends on DEBUG_KERNEL && PROC_FS
 264         help
 265           If you say Y here, additional code will be inserted into the
 266           timer routines to collect statistics about kernel timers being
 267           reprogrammed. The statistics can be read from /proc/timer_stats.
 268           The statistics collection is started by writing 1 to /proc/timer_stats,
 269           writing 0 stops it. This feature is useful to collect information
 270           about timer usage patterns in kernel and userspace. This feature
 271           is lightweight if enabled in the kernel config but not activated
 272           (it defaults to deactivated on bootup and will only be activated
 273           if some application like powertop activates it explicitly).
 274
 275 config DEBUG_OBJECTS
 276         bool "Debug object operations"
 277         depends on DEBUG_KERNEL
 278         help
 279           If you say Y here, additional code will be inserted into the
 280           kernel to track the life time of various objects and validate
 281           the operations on those objects.
 282
 283 config DEBUG_OBJECTS_SELFTEST
 284         bool "Debug objects selftest"
 285         depends on DEBUG_OBJECTS
 286         help
 287           This enables the selftest of the object debug code.
 288
 289 config DEBUG_OBJECTS_FREE
 290         bool "Debug objects in freed memory"
 291         depends on DEBUG_OBJECTS
 292         help
 293           This enables checks whether a k/v free operation frees an area
 294           which contains an object which has not been deactivated
 295           properly. This can make kmalloc/kfree-intensive workloads
 296           much slower.
 297
 298 config DEBUG_OBJECTS_TIMERS
 299         bool "Debug timer objects"
 300         depends on DEBUG_OBJECTS
 301         help
 302           If you say Y here, additional code will be inserted into the
 303           timer routines to track the life time of timer objects and
 304           validate the timer operations.
 305
 306 config DEBUG_OBJECTS_WORK
 307         bool "Debug work objects"
 308         depends on DEBUG_OBJECTS
 309         help
 310           If you say Y here, additional code will be inserted into the
 311           work queue routines to track the life time of work objects and
 312           validate the work operations.
 313
 314 config DEBUG_OBJECTS_RCU_HEAD
 315         bool "Debug RCU callbacks objects"
 316         depends on DEBUG_OBJECTS && PREEMPT
 317         help
 318           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 319
 320 config DEBUG_OBJECTS_ENABLE_DEFAULT
 321         int "debug_objects bootup default value (0-1)"
 322         range 0 1
 323         default "1"
 324         depends on DEBUG_OBJECTS
 325         help
 326           Debug objects boot parameter default value
 327
 328 config DEBUG_SLAB
 329         bool "Debug slab memory allocations"
 330         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 331         help
 332           Say Y here to have the kernel do limited verification on memory
 333           allocation as well as poisoning memory on free to catch use of freed
 334           memory. This can make kmalloc/kfree-intensive workloads much slower.
 335
 336 config DEBUG_SLAB_LEAK
 337         bool "Memory leak debugging"
 338         depends on DEBUG_SLAB
 339
 340 config SLUB_DEBUG_ON
 341         bool "SLUB debugging on by default"
 342         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 343         default n
 344         help
 345           Boot with debugging on by default. SLUB boots by default with
 346           the runtime debug capabilities switched off. Enabling this is
 347           equivalent to specifying the "slub_debug" parameter on boot.
 348           There is no support for more fine grained debug control like
 349           possible with slub_debug=xxx. SLUB debugging may be switched
 350           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 351           "slub_debug=-".
 352
 353 config SLUB_STATS
 354         default n
 355         bool "Enable SLUB performance statistics"
 356         depends on SLUB && SLUB_DEBUG && SYSFS
 357         help
 358           SLUB statistics are useful to debug SLUBs allocation behavior in
 359           order find ways to optimize the allocator. This should never be
 360           enabled for production use since keeping statistics slows down
 361           the allocator by a few percentage points. The slabinfo command
 362           supports the determination of the most active slabs to figure
 363           out which slabs are relevant to a particular load.
 364           Try running: slabinfo -DA
 365
 366 config DEBUG_KMEMLEAK
 367         bool "Kernel memory leak detector"
 368         depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
 369                 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE)
 370
 371         select DEBUG_FS if SYSFS
 372         select STACKTRACE if STACKTRACE_SUPPORT
 373         select KALLSYMS
 374         select CRC32
 375         help
 376           Say Y here if you want to enable the memory leak
 377           detector. The memory allocation/freeing is traced in a way
 378           similar to the Boehm's conservative garbage collector, the
 379           difference being that the orphan objects are not freed but
 380           only shown in /sys/kernel/debug/kmemleak. Enabling this
 381           feature will introduce an overhead to memory
 382           allocations. See Documentation/kmemleak.txt for more
 383           details.
 384
 385           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 386           of finding leaks due to the slab objects poisoning.
 387
 388           In order to access the kmemleak file, debugfs needs to be
 389           mounted (usually at /sys/kernel/debug).
 390
 391 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 392         int "Maximum kmemleak early log entries"
 393         depends on DEBUG_KMEMLEAK
 394         range 200 40000
 395         default 400
 396         help
 397           Kmemleak must track all the memory allocations to avoid
 398           reporting false positives. Since memory may be allocated or
 399           freed before kmemleak is initialised, an early log buffer is
 400           used to store these actions. If kmemleak reports "early log
 401           buffer exceeded", please increase this value.
 402
 403 config DEBUG_KMEMLEAK_TEST
 404         tristate "Simple test for the kernel memory leak detector"
 405         depends on DEBUG_KMEMLEAK
 406         help
 407           Say Y or M here to build a test for the kernel memory leak
 408           detector. This option enables a module that explicitly leaks
 409           memory.
 410
 411           If unsure, say N.
 412
 413 config DEBUG_KMEMLEAK_DEFAULT_OFF
 414         bool "Default kmemleak to off"
 415         depends on DEBUG_KMEMLEAK
 416         help
 417           Say Y here to disable kmemleak by default. It can then be enabled
 418           on the command line via kmemleak=on.
 419
 420 config DEBUG_PREEMPT
 421         bool "Debug preemptible kernel"
 422         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 423         default y
 424         help
 425           If you say Y here then the kernel will use a debug variant of the
 426           commonly used smp_processor_id() function and will print warnings
 427           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 428           will detect preemption count underflows.
 429
 430 config DEBUG_RT_MUTEXES
 431         bool "RT Mutex debugging, deadlock detection"
 432         depends on DEBUG_KERNEL && RT_MUTEXES
 433         help
 434          This allows rt mutex semantics violations and rt mutex related
 435          deadlocks (lockups) to be detected and reported automatically.
 436
 437 config DEBUG_PI_LIST
 438         bool
 439         default y
 440         depends on DEBUG_RT_MUTEXES
 441
 442 config RT_MUTEX_TESTER
 443         bool "Built-in scriptable tester for rt-mutexes"
 444         depends on DEBUG_KERNEL && RT_MUTEXES
 445         help
 446           This option enables a rt-mutex tester.
 447
 448 config DEBUG_SPINLOCK
 449         bool "Spinlock and rw-lock debugging: basic checks"
 450         depends on DEBUG_KERNEL
 451         help
 452           Say Y here and build SMP to catch missing spinlock initialization
 453           and certain other kinds of spinlock errors commonly made.  This is
 454           best used in conjunction with the NMI watchdog so that spinlock
 455           deadlocks are also debuggable.
 456
 457 config DEBUG_MUTEXES
 458         bool "Mutex debugging: basic checks"
 459         depends on DEBUG_KERNEL
 460         help
 461          This feature allows mutex semantics violations to be detected and
 462          reported.
 463
 464 config DEBUG_LOCK_ALLOC
 465         bool "Lock debugging: detect incorrect freeing of live locks"
 466         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 467         select DEBUG_SPINLOCK
 468         select DEBUG_MUTEXES
 469         select LOCKDEP
 470         help
 471          This feature will check whether any held lock (spinlock, rwlock,
 472          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 473          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 474          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 475          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 476          held during task exit.
 477
 478 config PROVE_LOCKING
 479         bool "Lock debugging: prove locking correctness"
 480         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 481         select LOCKDEP
 482         select DEBUG_SPINLOCK
 483         select DEBUG_MUTEXES
 484         select DEBUG_LOCK_ALLOC
 485         default n
 486         help
 487          This feature enables the kernel to prove that all locking
 488          that occurs in the kernel runtime is mathematically
 489          correct: that under no circumstance could an arbitrary (and
 490          not yet triggered) combination of observed locking
 491          sequences (on an arbitrary number of CPUs, running an
 492          arbitrary number of tasks and interrupt contexts) cause a
 493          deadlock.
 494
 495          In short, this feature enables the kernel to report locking
 496          related deadlocks before they actually occur.
 497
 498          The proof does not depend on how hard and complex a
 499          deadlock scenario would be to trigger: how many
 500          participant CPUs, tasks and irq-contexts would be needed
 501          for it to trigger. The proof also does not depend on
 502          timing: if a race and a resulting deadlock is possible
 503          theoretically (no matter how unlikely the race scenario
 504          is), it will be proven so and will immediately be
 505          reported by the kernel (once the event is observed that
 506          makes the deadlock theoretically possible).
 507
 508          If a deadlock is impossible (i.e. the locking rules, as
 509          observed by the kernel, are mathematically correct), the
 510          kernel reports nothing.
 511
 512          NOTE: this feature can also be enabled for rwlocks, mutexes
 513          and rwsems - in which case all dependencies between these
 514          different locking variants are observed and mapped too, and
 515          the proof of observed correctness is also maintained for an
 516          arbitrary combination of these separate locking variants.
 517
 518          For more details, see Documentation/lockdep-design.txt.
 519
 520 config PROVE_RCU
 521         bool "RCU debugging: prove RCU correctness"
 522         depends on PROVE_LOCKING
 523         default n
 524         help
 525          This feature enables lockdep extensions that check for correct
 526          use of RCU APIs.  This is currently under development.  Say Y
 527          if you want to debug RCU usage or help work on the PROVE_RCU
 528          feature.
 529
 530          Say N if you are unsure.
 531
 532 config PROVE_RCU_REPEATEDLY
 533         bool "RCU debugging: don't disable PROVE_RCU on first splat"
 534         depends on PROVE_RCU
 535         default n
 536         help
 537          By itself, PROVE_RCU will disable checking upon issuing the
 538          first warning (or "splat").  This feature prevents such
 539          disabling, allowing multiple RCU-lockdep warnings to be printed
 540          on a single reboot.
 541
 542          Say N if you are unsure.
 543
 544 config LOCKDEP
 545         bool
 546         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 547         select STACKTRACE
 548         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 549         select KALLSYMS
 550         select KALLSYMS_ALL
 551
 552 config LOCK_STAT
 553         bool "Lock usage statistics"
 554         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 555         select LOCKDEP
 556         select DEBUG_SPINLOCK
 557         select DEBUG_MUTEXES
 558         select DEBUG_LOCK_ALLOC
 559         default n
 560         help
 561          This feature enables tracking lock contention points
 562
 563          For more details, see Documentation/lockstat.txt
 564
 565          This also enables lock events required by "perf lock",
 566          subcommand of perf.
 567          If you want to use "perf lock", you also need to turn on
 568          CONFIG_EVENT_TRACING.
 569
 570          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 571          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 572
 573 config DEBUG_LOCKDEP
 574         bool "Lock dependency engine debugging"
 575         depends on DEBUG_KERNEL && LOCKDEP
 576         help
 577           If you say Y here, the lock dependency engine will do
 578           additional runtime checks to debug itself, at the price
 579           of more runtime overhead.
 580
 581 config TRACE_IRQFLAGS
 582         depends on DEBUG_KERNEL
 583         bool
 584         default y
 585         depends on TRACE_IRQFLAGS_SUPPORT
 586         depends on PROVE_LOCKING
 587
 588 config DEBUG_SPINLOCK_SLEEP
 589         bool "Spinlock debugging: sleep-inside-spinlock checking"
 590         depends on DEBUG_KERNEL
 591         help
 592           If you say Y here, various routines which may sleep will become very
 593           noisy if they are called with a spinlock held.
 594
 595 config DEBUG_LOCKING_API_SELFTESTS
 596         bool "Locking API boot-time self-tests"
 597         depends on DEBUG_KERNEL
 598         help
 599           Say Y here if you want the kernel to run a short self-test during
 600           bootup. The self-test checks whether common types of locking bugs
 601           are detected by debugging mechanisms or not. (if you disable
 602           lock debugging then those bugs wont be detected of course.)
 603           The following locking APIs are covered: spinlocks, rwlocks,
 604           mutexes and rwsems.
 605
 606 config STACKTRACE
 607         bool
 608         depends on STACKTRACE_SUPPORT
 609
 610 config DEBUG_KOBJECT
 611         bool "kobject debugging"
 612         depends on DEBUG_KERNEL
 613         help
 614           If you say Y here, some extra kobject debugging messages will be sent
 615           to the syslog.
 616
 617 config DEBUG_HIGHMEM
 618         bool "Highmem debugging"
 619         depends on DEBUG_KERNEL && HIGHMEM
 620         help
 621           This options enables addition error checking for high memory systems.
 622           Disable for production systems.
 623
 624 config DEBUG_BUGVERBOSE
 625         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 626         depends on BUG
 627         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 628                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 629         default y
 630         help
 631           Say Y here to make BUG() panics output the file name and line number
 632           of the BUG call as well as the EIP and oops trace.  This aids
 633           debugging but costs about 70-100K of memory.
 634
 635 config DEBUG_INFO
 636         bool "Compile the kernel with debug info"
 637         depends on DEBUG_KERNEL
 638         help
 639           If you say Y here the resulting kernel image will include
 640           debugging info resulting in a larger kernel image.
 641           This adds debug symbols to the kernel and modules (gcc -g), and
 642           is needed if you intend to use kernel crashdump or binary object
 643           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 644           Say Y here only if you plan to debug the kernel.
 645
 646           If unsure, say N.
 647
 648 config DEBUG_INFO_REDUCED
 649         bool "Reduce debugging information"
 650         depends on DEBUG_INFO
 651         help
 652           If you say Y here gcc is instructed to generate less debugging
 653           information for structure types. This means that tools that
 654           need full debugging information (like kgdb or systemtap) won't
 655           be happy. But if you merely need debugging information to
 656           resolve line numbers there is no loss. Advantage is that
 657           build directory object sizes shrink dramatically over a full
 658           DEBUG_INFO build and compile times are reduced too.
 659           Only works with newer gcc versions.
 660
 661 config DEBUG_VM
 662         bool "Debug VM"
 663         depends on DEBUG_KERNEL
 664         help
 665           Enable this to turn on extended checks in the virtual-memory system
 666           that may impact performance.
 667
 668           If unsure, say N.
 669
 670 config DEBUG_VIRTUAL
 671         bool "Debug VM translations"
 672         depends on DEBUG_KERNEL && X86
 673         help
 674           Enable some costly sanity checks in virtual to page code. This can
 675           catch mistakes with virt_to_page() and friends.
 676
 677           If unsure, say N.
 678
 679 config DEBUG_NOMMU_REGIONS
 680         bool "Debug the global anon/private NOMMU mapping region tree"
 681         depends on DEBUG_KERNEL && !MMU
 682         help
 683           This option causes the global tree of anonymous and private mapping
 684           regions to be regularly checked for invalid topology.
 685
 686 config DEBUG_WRITECOUNT
 687         bool "Debug filesystem writers count"
 688         depends on DEBUG_KERNEL
 689         help
 690           Enable this to catch wrong use of the writers count in struct
 691           vfsmount.  This will increase the size of each file struct by
 692           32 bits.
 693
 694           If unsure, say N.
 695
 696 config DEBUG_MEMORY_INIT
 697         bool "Debug memory initialisation" if EMBEDDED
 698         default !EMBEDDED
 699         help
 700           Enable this for additional checks during memory initialisation.
 701           The sanity checks verify aspects of the VM such as the memory model
 702           and other information provided by the architecture. Verbose
 703           information will be printed at KERN_DEBUG loglevel depending
 704           on the mminit_loglevel= command-line option.
 705
 706           If unsure, say Y
 707
 708 config DEBUG_LIST
 709         bool "Debug linked list manipulation"
 710         depends on DEBUG_KERNEL
 711         help
 712           Enable this to turn on extended checks in the linked-list
 713           walking routines.
 714
 715           If unsure, say N.
 716
 717 config DEBUG_SG
 718         bool "Debug SG table operations"
 719         depends on DEBUG_KERNEL
 720         help
 721           Enable this to turn on checks on scatter-gather tables. This can
 722           help find problems with drivers that do not properly initialize
 723           their sg tables.
 724
 725           If unsure, say N.
 726
 727 config DEBUG_NOTIFIERS
 728         bool "Debug notifier call chains"
 729         depends on DEBUG_KERNEL
 730         help
 731           Enable this to turn on sanity checking for notifier call chains.
 732           This is most useful for kernel developers to make sure that
 733           modules properly unregister themselves from notifier chains.
 734           This is a relatively cheap check but if you care about maximum
 735           performance, say N.
 736
 737 config DEBUG_CREDENTIALS
 738         bool "Debug credential management"
 739         depends on DEBUG_KERNEL
 740         help
 741           Enable this to turn on some debug checking for credential
 742           management.  The additional code keeps track of the number of
 743           pointers from task_structs to any given cred struct, and checks to
 744           see that this number never exceeds the usage count of the cred
 745           struct.
 746
 747           Furthermore, if SELinux is enabled, this also checks that the
 748           security pointer in the cred struct is never seen to be invalid.
 749
 750           If unsure, say N.
 751
 752 #
 753 # Select this config option from the architecture Kconfig, if it
 754 # it is preferred to always offer frame pointers as a config
 755 # option on the architecture (regardless of KERNEL_DEBUG):
 756 #
 757 config ARCH_WANT_FRAME_POINTERS
 758         bool
 759         help
 760
 761 config FRAME_POINTER
 762         bool "Compile the kernel with frame pointers"
 763         depends on DEBUG_KERNEL && \
 764                 (CRIS || M68K || M68KNOMMU || FRV || UML || \
 765                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 766                 ARCH_WANT_FRAME_POINTERS
 767         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 768         help
 769           If you say Y here the resulting kernel image will be slightly
 770           larger and slower, but it gives very useful debugging information
 771           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 772
 773 config BOOT_PRINTK_DELAY
 774         bool "Delay each boot printk message by N milliseconds"
 775         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 776         help
 777           This build option allows you to read kernel boot messages
 778           by inserting a short delay after each one.  The delay is
 779           specified in milliseconds on the kernel command line,
 780           using "boot_delay=N".
 781
 782           It is likely that you would also need to use "lpj=M" to preset
 783           the "loops per jiffie" value.
 784           See a previous boot log for the "lpj" value to use for your
 785           system, and then set "lpj=M" before setting "boot_delay=N".
 786           NOTE:  Using this option may adversely affect SMP systems.
 787           I.e., processors other than the first one may not boot up.
 788           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 789           what it believes to be lockup conditions.
 790
 791 config RCU_TORTURE_TEST
 792         tristate "torture tests for RCU"
 793         depends on DEBUG_KERNEL
 794         default n
 795         help
 796           This option provides a kernel module that runs torture tests
 797           on the RCU infrastructure.  The kernel module may be built
 798           after the fact on the running kernel to be tested, if desired.
 799
 800           Say Y here if you want RCU torture tests to be built into
 801           the kernel.
 802           Say M if you want the RCU torture tests to build as a module.
 803           Say N if you are unsure.
 804
 805 config RCU_TORTURE_TEST_RUNNABLE
 806         bool "torture tests for RCU runnable by default"
 807         depends on RCU_TORTURE_TEST = y
 808         default n
 809         help
 810           This option provides a way to build the RCU torture tests
 811           directly into the kernel without them starting up at boot
 812           time.  You can use /proc/sys/kernel/rcutorture_runnable
 813           to manually override this setting.  This /proc file is
 814           available only when the RCU torture tests have been built
 815           into the kernel.
 816
 817           Say Y here if you want the RCU torture tests to start during
 818           boot (you probably don't).
 819           Say N here if you want the RCU torture tests to start only
 820           after being manually enabled via /proc.
 821
 822 config RCU_CPU_STALL_DETECTOR
 823         bool "Check for stalled CPUs delaying RCU grace periods"
 824         depends on TREE_RCU || TREE_PREEMPT_RCU
 825         default y
 826         help
 827           This option causes RCU to printk information on which
 828           CPUs are delaying the current grace period, but only when
 829           the grace period extends for excessive time periods.
 830
 831           Say N if you want to disable such checks.
 832
 833           Say Y if you are unsure.
 834
 835 config RCU_CPU_STALL_VERBOSE
 836         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 837         depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
 838         default y
 839         help
 840           This option causes RCU to printk detailed per-task information
 841           for any tasks that are stalling the current RCU grace period.
 842
 843           Say N if you are unsure.
 844
 845           Say Y if you want to enable such checks.
 846
 847 config KPROBES_SANITY_TEST
 848         bool "Kprobes sanity tests"
 849         depends on DEBUG_KERNEL
 850         depends on KPROBES
 851         default n
 852         help
 853           This option provides for testing basic kprobes functionality on
 854           boot. A sample kprobe, jprobe and kretprobe are inserted and
 855           verified for functionality.
 856
 857           Say N if you are unsure.
 858
 859 config BACKTRACE_SELF_TEST
 860         tristate "Self test for the backtrace code"
 861         depends on DEBUG_KERNEL
 862         default n
 863         help
 864           This option provides a kernel module that can be used to test
 865           the kernel stack backtrace code. This option is not useful
 866           for distributions or general kernels, but only for kernel
 867           developers working on architecture code.
 868
 869           Note that if you want to also test saved backtraces, you will
 870           have to enable STACKTRACE as well.
 871
 872           Say N if you are unsure.
 873
 874 config DEBUG_BLOCK_EXT_DEVT
 875         bool "Force extended block device numbers and spread them"
 876         depends on DEBUG_KERNEL
 877         depends on BLOCK
 878         default n
 879         help
 880           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 881           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 882           YOU ARE DOING.  Distros, please enable this and fix whatever
 883           is broken.
 884
 885           Conventionally, block device numbers are allocated from
 886           predetermined contiguous area.  However, extended block area
 887           may introduce non-contiguous block device numbers.  This
 888           option forces most block device numbers to be allocated from
 889           the extended space and spreads them to discover kernel or
 890           userland code paths which assume predetermined contiguous
 891           device number allocation.
 892
 893           Note that turning on this debug option shuffles all the
 894           device numbers for all IDE and SCSI devices including libata
 895           ones, so root partition specified using device number
 896           directly (via rdev or root=MAJ:MIN) won't work anymore.
 897           Textual device names (root=/dev/sdXn) will continue to work.
 898
 899           Say N if you are unsure.
 900
 901 config DEBUG_FORCE_WEAK_PER_CPU
 902         bool "Force weak per-cpu definitions"
 903         depends on DEBUG_KERNEL
 904         help
 905           s390 and alpha require percpu variables in modules to be
 906           defined weak to work around addressing range issue which
 907           puts the following two restrictions on percpu variable
 908           definitions.
 909
 910           1. percpu symbols must be unique whether static or not
 911           2. percpu variables can't be defined inside a function
 912
 913           To ensure that generic code follows the above rules, this
 914           option forces all percpu variables to be defined as weak.
 915
 916 config LKDTM
 917         tristate "Linux Kernel Dump Test Tool Module"
 918         depends on DEBUG_FS
 919         depends on BLOCK
 920         default n
 921         help
 922         This module enables testing of the different dumping mechanisms by
 923         inducing system failures at predefined crash points.
 924         If you don't need it: say N
 925         Choose M here to compile this code as a module. The module will be
 926         called lkdtm.
 927
 928         Documentation on how to use the module can be found in
 929         Documentation/fault-injection/provoke-crashes.txt
 930
 931 config CPU_NOTIFIER_ERROR_INJECT
 932         tristate "CPU notifier error injection module"
 933         depends on HOTPLUG_CPU && DEBUG_KERNEL
 934         help
 935           This option provides a kernel module that can be used to test
 936           the error handling of the cpu notifiers
 937
 938           To compile this code as a module, choose M here: the module will
 939           be called cpu-notifier-error-inject.
 940
 941           If unsure, say N.
 942
 943 config FAULT_INJECTION
 944         bool "Fault-injection framework"
 945         depends on DEBUG_KERNEL
 946         help
 947           Provide fault-injection framework.
 948           For more details, see Documentation/fault-injection/.
 949
 950 config FAILSLAB
 951         bool "Fault-injection capability for kmalloc"
 952         depends on FAULT_INJECTION
 953         depends on SLAB || SLUB
 954         help
 955           Provide fault-injection capability for kmalloc.
 956
 957 config FAIL_PAGE_ALLOC
 958         bool "Fault-injection capabilitiy for alloc_pages()"
 959         depends on FAULT_INJECTION
 960         help
 961           Provide fault-injection capability for alloc_pages().
 962
 963 config FAIL_MAKE_REQUEST
 964         bool "Fault-injection capability for disk IO"
 965         depends on FAULT_INJECTION && BLOCK
 966         help
 967           Provide fault-injection capability for disk IO.
 968
 969 config FAIL_IO_TIMEOUT
 970         bool "Fault-injection capability for faking disk interrupts"
 971         depends on FAULT_INJECTION && BLOCK
 972         help
 973           Provide fault-injection capability on end IO handling. This
 974           will make the block layer "forget" an interrupt as configured,
 975           thus exercising the error handling.
 976
 977           Only works with drivers that use the generic timeout handling,
 978           for others it wont do anything.
 979
 980 config FAULT_INJECTION_DEBUG_FS
 981         bool "Debugfs entries for fault-injection capabilities"
 982         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 983         help
 984           Enable configuration of fault-injection capabilities via debugfs.
 985
 986 config FAULT_INJECTION_STACKTRACE_FILTER
 987         bool "stacktrace filter for fault-injection capabilities"
 988         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 989         depends on !X86_64
 990         select STACKTRACE
 991         select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
 992         help
 993           Provide stacktrace filter for fault-injection capabilities
 994
 995 config LATENCYTOP
 996         bool "Latency measuring infrastructure"
 997         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
 998         select KALLSYMS
 999         select KALLSYMS_ALL
1000         select STACKTRACE
1001         select SCHEDSTATS
1002         select SCHED_DEBUG
1003         depends on HAVE_LATENCYTOP_SUPPORT
1004         help
1005           Enable this option if you want to use the LatencyTOP tool
1006           to find out which userspace is blocking on what kernel operations.
1007
1008 config SYSCTL_SYSCALL_CHECK
1009         bool "Sysctl checks"
1010         depends on SYSCTL
1011         ---help---
1012           sys_sysctl uses binary paths that have been found challenging
1013           to properly maintain and use. This enables checks that help
1014           you to keep things correct.
1015
1016 source mm/Kconfig.debug
1017 source kernel/trace/Kconfig
1018
1019 config PROVIDE_OHCI1394_DMA_INIT
1020         bool "Remote debugging over FireWire early on boot"
1021         depends on PCI && X86
1022         help
1023           If you want to debug problems which hang or crash the kernel early
1024           on boot and the crashing machine has a FireWire port, you can use
1025           this feature to remotely access the memory of the crashed machine
1026           over FireWire. This employs remote DMA as part of the OHCI1394
1027           specification which is now the standard for FireWire controllers.
1028
1029           With remote DMA, you can monitor the printk buffer remotely using
1030           firescope and access all memory below 4GB using fireproxy from gdb.
1031           Even controlling a kernel debugger is possible using remote DMA.
1032
1033           Usage:
1034
1035           If ohci1394_dma=early is used as boot parameter, it will initialize
1036           all OHCI1394 controllers which are found in the PCI config space.
1037
1038           As all changes to the FireWire bus such as enabling and disabling
1039           devices cause a bus reset and thereby disable remote DMA for all
1040           devices, be sure to have the cable plugged and FireWire enabled on
1041           the debugging host before booting the debug target for debugging.
1042
1043           This code (~1k) is freed after boot. By then, the firewire stack
1044           in charge of the OHCI-1394 controllers should be used instead.
1045
1046           See Documentation/debugging-via-ohci1394.txt for more information.
1047
1048 config FIREWIRE_OHCI_REMOTE_DMA
1049         bool "Remote debugging over FireWire with firewire-ohci"
1050         depends on FIREWIRE_OHCI
1051         help
1052           This option lets you use the FireWire bus for remote debugging
1053           with help of the firewire-ohci driver. It enables unfiltered
1054           remote DMA in firewire-ohci.
1055           See Documentation/debugging-via-ohci1394.txt for more information.
1056
1057           If unsure, say N.
1058
1059 config BUILD_DOCSRC
1060         bool "Build targets in Documentation/ tree"
1061         depends on HEADERS_CHECK
1062         help
1063           This option attempts to build objects from the source files in the
1064           kernel Documentation/ tree.
1065
1066           Say N if you are unsure.
1067
1068 config DYNAMIC_DEBUG
1069         bool "Enable dynamic printk() support"
1070         default n
1071         depends on PRINTK
1072         depends on DEBUG_FS
1073         help
1074
1075           Compiles debug level messages into the kernel, which would not
1076           otherwise be available at runtime. These messages can then be
1077           enabled/disabled based on various levels of scope - per source file,
1078           function, module, format string, and line number. This mechanism
1079           implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1080           this compile option is a larger kernel text size of about 2%.
1081
1082           Usage:
1083
1084           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1085           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1086           filesystem must first be mounted before making use of this feature.
1087           We refer the control file as: <debugfs>/dynamic_debug/control. This
1088           file contains a list of the debug statements that can be enabled. The
1089           format for each line of the file is:
1090
1091                 filename:lineno [module]function flags format
1092
1093           filename : source file of the debug statement
1094           lineno : line number of the debug statement
1095           module : module that contains the debug statement
1096           function : function that contains the debug statement
1097           flags : 'p' means the line is turned 'on' for printing
1098           format : the format used for the debug statement
1099
1100           From a live system:
1101
1102                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1103                 # filename:lineno [module]function flags format
1104                 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1105                 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1106                 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1107
1108           Example usage:
1109
1110                 // enable the message at line 1603 of file svcsock.c
1111                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1112                                                 <debugfs>/dynamic_debug/control
1113
1114                 // enable all the messages in file svcsock.c
1115                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1116                                                 <debugfs>/dynamic_debug/control
1117
1118                 // enable all the messages in the NFS server module
1119                 nullarbor:~ # echo -n 'module nfsd +p' >
1120                                                 <debugfs>/dynamic_debug/control
1121
1122                 // enable all 12 messages in the function svc_process()
1123                 nullarbor:~ # echo -n 'func svc_process +p' >
1124                                                 <debugfs>/dynamic_debug/control
1125
1126                 // disable all 12 messages in the function svc_process()
1127                 nullarbor:~ # echo -n 'func svc_process -p' >
1128                                                 <debugfs>/dynamic_debug/control
1129
1130           See Documentation/dynamic-debug-howto.txt for additional information.
1131
1132 config DMA_API_DEBUG
1133         bool "Enable debugging of DMA-API usage"
1134         depends on HAVE_DMA_API_DEBUG
1135         help
1136           Enable this option to debug the use of the DMA API by device drivers.
1137           With this option you will be able to detect common bugs in device
1138           drivers like double-freeing of DMA mappings or freeing mappings that
1139           were never allocated.
1140           This option causes a performance degredation.  Use only if you want
1141           to debug device drivers. If unsure, say N.
1142
1143 config ATOMIC64_SELFTEST
1144         bool "Perform an atomic64_t self-test at boot"
1145         help
1146           Enable this option to test the atomic64_t functions at boot.
1147
1148           If unsure, say N.
1149
1150 source "samples/Kconfig"
1151
1152 source "lib/Kconfig.kgdb"
1153
1154 source "lib/Kconfig.kmemcheck"