lib/Kconfig.debug

   1
   2 config PRINTK_TIME
   3         bool "Show timing information on printks"
   4         depends on PRINTK
   5         help
   6           Selecting this option causes timing information to be
   7           included in printk output.  This allows you to measure
   8           the interval between kernel operations, including bootup
   9           operations.  This is useful for identifying long delays
  10           in kernel startup.
  11
  12 config DEFAULT_MESSAGE_LOGLEVEL
  13         int "Default message log level (1-7)"
  14         range 1 7
  15         default "4"
  16         help
  17           Default log level for printk statements with no specified priority.
  18
  19           This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
  20           that are auditing their logs closely may want to set it to a lower
  21           priority.
  22
  23 config ENABLE_WARN_DEPRECATED
  24         bool "Enable __deprecated logic"
  25         default y
  26         help
  27           Enable the __deprecated logic in the kernel build.
  28           Disable this to suppress the "warning: 'foo' is deprecated
  29           (declared at kernel/power/somefile.c:1234)" messages.
  30
  31 config ENABLE_MUST_CHECK
  32         bool "Enable __must_check logic"
  33         default y
  34         help
  35           Enable the __must_check logic in the kernel build.  Disable this to
  36           suppress the "warning: ignoring return value of 'foo', declared with
  37           attribute warn_unused_result" messages.
  38
  39 config FRAME_WARN
  40         int "Warn for stack frames larger than (needs gcc 4.4)"
  41         range 0 8192
  42         default 1024 if !64BIT
  43         default 2048 if 64BIT
  44         help
  45           Tell gcc to warn at build time for stack frames larger than this.
  46           Setting this too low will cause a lot of warnings.
  47           Setting it to 0 disables the warning.
  48           Requires gcc 4.4
  49
  50 config MAGIC_SYSRQ
  51         bool "Magic SysRq key"
  52         depends on !UML
  53         help
  54           If you say Y here, you will have some control over the system even
  55           if the system crashes for example during kernel debugging (e.g., you
  56           will be able to flush the buffer cache to disk, reboot the system
  57           immediately or dump some status information). This is accomplished
  58           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  59           also works on a serial console (on PC hardware at least), if you
  60           send a BREAK and then within 5 seconds a command keypress. The
  61           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  62           unless you really know what this hack does.
  63
  64 config STRIP_ASM_SYMS
  65         bool "Strip assembler-generated symbols during link"
  66         default n
  67         help
  68           Strip internal assembler-generated symbols during a link (symbols
  69           that look like '.Lxxx') so they don't pollute the output of
  70           get_wchan() and suchlike.
  71
  72 config UNUSED_SYMBOLS
  73         bool "Enable unused/obsolete exported symbols"
  74         default y if X86
  75         help
  76           Unused but exported symbols make the kernel needlessly bigger.  For
  77           that reason most of these unused exports will soon be removed.  This
  78           option is provided temporarily to provide a transition period in case
  79           some external kernel module needs one of these symbols anyway. If you
  80           encounter such a case in your module, consider if you are actually
  81           using the right API.  (rationale: since nobody in the kernel is using
  82           this in a module, there is a pretty good chance it's actually the
  83           wrong interface to use).  If you really need the symbol, please send a
  84           mail to the linux kernel mailing list mentioning the symbol and why
  85           you really need it, and what the merge plan to the mainline kernel for
  86           your module is.
  87
  88 config DEBUG_FS
  89         bool "Debug Filesystem"
  90         help
  91           debugfs is a virtual file system that kernel developers use to put
  92           debugging files into.  Enable this option to be able to read and
  93           write to these files.
  94
  95           For detailed documentation on the debugfs API, see
  96           Documentation/DocBook/filesystems.
  97
  98           If unsure, say N.
  99
 100 config HEADERS_CHECK
 101         bool "Run 'make headers_check' when building vmlinux"
 102         depends on !UML
 103         help
 104           This option will extract the user-visible kernel headers whenever
 105           building the kernel, and will run basic sanity checks on them to
 106           ensure that exported files do not attempt to include files which
 107           were not exported, etc.
 108
 109           If you're making modifications to header files which are
 110           relevant for userspace, say 'Y', and check the headers
 111           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 112           your build tree), to make sure they're suitable.
 113
 114 config DEBUG_SECTION_MISMATCH
 115         bool "Enable full Section mismatch analysis"
 116         help
 117           The section mismatch analysis checks if there are illegal
 118           references from one section to another section.
 119           Linux will during link or during runtime drop some sections
 120           and any use of code/data previously in these sections will
 121           most likely result in an oops.
 122           In the code functions and variables are annotated with
 123           __init, __devinit etc. (see full list in include/linux/init.h)
 124           which results in the code/data being placed in specific sections.
 125           The section mismatch analysis is always done after a full
 126           kernel build but enabling this option will in addition
 127           do the following:
 128           - Add the option -fno-inline-functions-called-once to gcc
 129             When inlining a function annotated __init in a non-init
 130             function we would lose the section information and thus
 131             the analysis would not catch the illegal reference.
 132             This option tells gcc to inline less but will also
 133             result in a larger kernel.
 134           - Run the section mismatch analysis for each module/built-in.o
 135             When we run the section mismatch analysis on vmlinux.o we
 136             lose valueble information about where the mismatch was
 137             introduced.
 138             Running the analysis for each module/built-in.o file
 139             will tell where the mismatch happens much closer to the
 140             source. The drawback is that we will report the same
 141             mismatch at least twice.
 142           - Enable verbose reporting from modpost to help solving
 143             the section mismatches reported.
 144
 145 config DEBUG_KERNEL
 146         bool "Kernel debugging"
 147         help
 148           Say Y here if you are developing drivers or trying to debug and
 149           identify kernel problems.
 150
 151 config DEBUG_SHIRQ
 152         bool "Debug shared IRQ handlers"
 153         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 154         help
 155           Enable this to generate a spurious interrupt as soon as a shared
 156           interrupt handler is registered, and just before one is deregistered.
 157           Drivers ought to be able to handle interrupts coming in at those
 158           points; some don't and need to be caught.
 159
 160 config LOCKUP_DETECTOR
 161         bool "Detect Hard and Soft Lockups"
 162         depends on DEBUG_KERNEL && !S390
 163         help
 164           Say Y here to enable the kernel to act as a watchdog to detect
 165           hard and soft lockups.
 166
 167           Softlockups are bugs that cause the kernel to loop in kernel
 168           mode for more than 60 seconds, without giving other tasks a
 169           chance to run.  The current stack trace is displayed upon
 170           detection and the system will stay locked up.
 171
 172           Hardlockups are bugs that cause the CPU to loop in kernel mode
 173           for more than 60 seconds, without letting other interrupts have a
 174           chance to run.  The current stack trace is displayed upon detection
 175           and the system will stay locked up.
 176
 177           The overhead should be minimal.  A periodic hrtimer runs to
 178           generate interrupts and kick the watchdog task every 10-12 seconds.
 179           An NMI is generated every 60 seconds or so to check for hardlockups.
 180
 181 config HARDLOCKUP_DETECTOR
 182         def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
 183                  !ARCH_HAS_NMI_WATCHDOG
 184
 185 config BOOTPARAM_HARDLOCKUP_PANIC
 186         bool "Panic (Reboot) On Hard Lockups"
 187         depends on LOCKUP_DETECTOR
 188         help
 189           Say Y here to enable the kernel to panic on "hard lockups",
 190           which are bugs that cause the kernel to loop in kernel
 191           mode with interrupts disabled for more than 60 seconds.
 192
 193           Say N if unsure.
 194
 195 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
 196         int
 197         depends on LOCKUP_DETECTOR
 198         range 0 1
 199         default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
 200         default 1 if BOOTPARAM_HARDLOCKUP_PANIC
 201
 202 config BOOTPARAM_SOFTLOCKUP_PANIC
 203         bool "Panic (Reboot) On Soft Lockups"
 204         depends on LOCKUP_DETECTOR
 205         help
 206           Say Y here to enable the kernel to panic on "soft lockups",
 207           which are bugs that cause the kernel to loop in kernel
 208           mode for more than 60 seconds, without giving other tasks a
 209           chance to run.
 210
 211           The panic can be used in combination with panic_timeout,
 212           to cause the system to reboot automatically after a
 213           lockup has been detected. This feature is useful for
 214           high-availability systems that have uptime guarantees and
 215           where a lockup must be resolved ASAP.
 216
 217           Say N if unsure.
 218
 219 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 220         int
 221         depends on LOCKUP_DETECTOR
 222         range 0 1
 223         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 224         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 225
 226 config DETECT_HUNG_TASK
 227         bool "Detect Hung Tasks"
 228         depends on DEBUG_KERNEL
 229         default DETECT_SOFTLOCKUP
 230         help
 231           Say Y here to enable the kernel to detect "hung tasks",
 232           which are bugs that cause the task to be stuck in
 233           uninterruptible "D" state indefinitiley.
 234
 235           When a hung task is detected, the kernel will print the
 236           current stack trace (which you should report), but the
 237           task will stay in uninterruptible state. If lockdep is
 238           enabled then all held locks will also be reported. This
 239           feature has negligible overhead.
 240
 241 config DEFAULT_HUNG_TASK_TIMEOUT
 242         int "Default timeout for hung task detection (in seconds)"
 243         depends on DETECT_HUNG_TASK
 244         default 120
 245         help
 246           This option controls the default timeout (in seconds) used
 247           to determine when a task has become non-responsive and should
 248           be considered hung.
 249
 250           It can be adjusted at runtime via the kernel.hung_task_timeout
 251           sysctl or by writing a value to /proc/sys/kernel/hung_task_timeout.
 252
 253           A timeout of 0 disables the check.  The default is two minutes.
 254           Keeping the default should be fine in most cases.
 255
 256 config BOOTPARAM_HUNG_TASK_PANIC
 257         bool "Panic (Reboot) On Hung Tasks"
 258         depends on DETECT_HUNG_TASK
 259         help
 260           Say Y here to enable the kernel to panic on "hung tasks",
 261           which are bugs that cause the kernel to leave a task stuck
 262           in uninterruptible "D" state.
 263
 264           The panic can be used in combination with panic_timeout,
 265           to cause the system to reboot automatically after a
 266           hung task has been detected. This feature is useful for
 267           high-availability systems that have uptime guarantees and
 268           where a hung tasks must be resolved ASAP.
 269
 270           Say N if unsure.
 271
 272 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 273         int
 274         depends on DETECT_HUNG_TASK
 275         range 0 1
 276         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 277         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 278
 279 config SCHED_DEBUG
 280         bool "Collect scheduler debugging info"
 281         depends on DEBUG_KERNEL && PROC_FS
 282         default y
 283         help
 284           If you say Y here, the /proc/sched_debug file will be provided
 285           that can help debug the scheduler. The runtime overhead of this
 286           option is minimal.
 287
 288 config SCHEDSTATS
 289         bool "Collect scheduler statistics"
 290         depends on DEBUG_KERNEL && PROC_FS
 291         help
 292           If you say Y here, additional code will be inserted into the
 293           scheduler and related routines to collect statistics about
 294           scheduler behavior and provide them in /proc/schedstat.  These
 295           stats may be useful for both tuning and debugging the scheduler
 296           If you aren't debugging the scheduler or trying to tune a specific
 297           application, you can say N to avoid the very slight overhead
 298           this adds.
 299
 300 config TIMER_STATS
 301         bool "Collect kernel timers statistics"
 302         depends on DEBUG_KERNEL && PROC_FS
 303         help
 304           If you say Y here, additional code will be inserted into the
 305           timer routines to collect statistics about kernel timers being
 306           reprogrammed. The statistics can be read from /proc/timer_stats.
 307           The statistics collection is started by writing 1 to /proc/timer_stats,
 308           writing 0 stops it. This feature is useful to collect information
 309           about timer usage patterns in kernel and userspace. This feature
 310           is lightweight if enabled in the kernel config but not activated
 311           (it defaults to deactivated on bootup and will only be activated
 312           if some application like powertop activates it explicitly).
 313
 314 config DEBUG_OBJECTS
 315         bool "Debug object operations"
 316         depends on DEBUG_KERNEL
 317         help
 318           If you say Y here, additional code will be inserted into the
 319           kernel to track the life time of various objects and validate
 320           the operations on those objects.
 321
 322 config DEBUG_OBJECTS_SELFTEST
 323         bool "Debug objects selftest"
 324         depends on DEBUG_OBJECTS
 325         help
 326           This enables the selftest of the object debug code.
 327
 328 config DEBUG_OBJECTS_FREE
 329         bool "Debug objects in freed memory"
 330         depends on DEBUG_OBJECTS
 331         help
 332           This enables checks whether a k/v free operation frees an area
 333           which contains an object which has not been deactivated
 334           properly. This can make kmalloc/kfree-intensive workloads
 335           much slower.
 336
 337 config DEBUG_OBJECTS_TIMERS
 338         bool "Debug timer objects"
 339         depends on DEBUG_OBJECTS
 340         help
 341           If you say Y here, additional code will be inserted into the
 342           timer routines to track the life time of timer objects and
 343           validate the timer operations.
 344
 345 config DEBUG_OBJECTS_WORK
 346         bool "Debug work objects"
 347         depends on DEBUG_OBJECTS
 348         help
 349           If you say Y here, additional code will be inserted into the
 350           work queue routines to track the life time of work objects and
 351           validate the work operations.
 352
 353 config DEBUG_OBJECTS_RCU_HEAD
 354         bool "Debug RCU callbacks objects"
 355         depends on DEBUG_OBJECTS && PREEMPT
 356         help
 357           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 358
 359 config DEBUG_OBJECTS_PERCPU_COUNTER
 360         bool "Debug percpu counter objects"
 361         depends on DEBUG_OBJECTS
 362         help
 363           If you say Y here, additional code will be inserted into the
 364           percpu counter routines to track the life time of percpu counter
 365           objects and validate the percpu counter operations.
 366
 367 config DEBUG_OBJECTS_ENABLE_DEFAULT
 368         int "debug_objects bootup default value (0-1)"
 369         range 0 1
 370         default "1"
 371         depends on DEBUG_OBJECTS
 372         help
 373           Debug objects boot parameter default value
 374
 375 config DEBUG_SLAB
 376         bool "Debug slab memory allocations"
 377         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 378         help
 379           Say Y here to have the kernel do limited verification on memory
 380           allocation as well as poisoning memory on free to catch use of freed
 381           memory. This can make kmalloc/kfree-intensive workloads much slower.
 382
 383 config DEBUG_SLAB_LEAK
 384         bool "Memory leak debugging"
 385         depends on DEBUG_SLAB
 386
 387 config SLUB_DEBUG_ON
 388         bool "SLUB debugging on by default"
 389         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 390         default n
 391         help
 392           Boot with debugging on by default. SLUB boots by default with
 393           the runtime debug capabilities switched off. Enabling this is
 394           equivalent to specifying the "slub_debug" parameter on boot.
 395           There is no support for more fine grained debug control like
 396           possible with slub_debug=xxx. SLUB debugging may be switched
 397           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 398           "slub_debug=-".
 399
 400 config SLUB_STATS
 401         default n
 402         bool "Enable SLUB performance statistics"
 403         depends on SLUB && SYSFS
 404         help
 405           SLUB statistics are useful to debug SLUBs allocation behavior in
 406           order find ways to optimize the allocator. This should never be
 407           enabled for production use since keeping statistics slows down
 408           the allocator by a few percentage points. The slabinfo command
 409           supports the determination of the most active slabs to figure
 410           out which slabs are relevant to a particular load.
 411           Try running: slabinfo -DA
 412
 413 config DEBUG_KMEMLEAK
 414         bool "Kernel memory leak detector"
 415         depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
 416                 (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
 417
 418         select DEBUG_FS
 419         select STACKTRACE if STACKTRACE_SUPPORT
 420         select KALLSYMS
 421         select CRC32
 422         help
 423           Say Y here if you want to enable the memory leak
 424           detector. The memory allocation/freeing is traced in a way
 425           similar to the Boehm's conservative garbage collector, the
 426           difference being that the orphan objects are not freed but
 427           only shown in /sys/kernel/debug/kmemleak. Enabling this
 428           feature will introduce an overhead to memory
 429           allocations. See Documentation/kmemleak.txt for more
 430           details.
 431
 432           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 433           of finding leaks due to the slab objects poisoning.
 434
 435           In order to access the kmemleak file, debugfs needs to be
 436           mounted (usually at /sys/kernel/debug).
 437
 438 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 439         int "Maximum kmemleak early log entries"
 440         depends on DEBUG_KMEMLEAK
 441         range 200 40000
 442         default 400
 443         help
 444           Kmemleak must track all the memory allocations to avoid
 445           reporting false positives. Since memory may be allocated or
 446           freed before kmemleak is initialised, an early log buffer is
 447           used to store these actions. If kmemleak reports "early log
 448           buffer exceeded", please increase this value.
 449
 450 config DEBUG_KMEMLEAK_TEST
 451         tristate "Simple test for the kernel memory leak detector"
 452         depends on DEBUG_KMEMLEAK && m
 453         help
 454           This option enables a module that explicitly leaks memory.
 455
 456           If unsure, say N.
 457
 458 config DEBUG_KMEMLEAK_DEFAULT_OFF
 459         bool "Default kmemleak to off"
 460         depends on DEBUG_KMEMLEAK
 461         help
 462           Say Y here to disable kmemleak by default. It can then be enabled
 463           on the command line via kmemleak=on.
 464
 465 config DEBUG_PREEMPT
 466         bool "Debug preemptible kernel"
 467         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 468         default y
 469         help
 470           If you say Y here then the kernel will use a debug variant of the
 471           commonly used smp_processor_id() function and will print warnings
 472           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 473           will detect preemption count underflows.
 474
 475 config DEBUG_RT_MUTEXES
 476         bool "RT Mutex debugging, deadlock detection"
 477         depends on DEBUG_KERNEL && RT_MUTEXES
 478         help
 479          This allows rt mutex semantics violations and rt mutex related
 480          deadlocks (lockups) to be detected and reported automatically.
 481
 482 config DEBUG_PI_LIST
 483         bool
 484         default y
 485         depends on DEBUG_RT_MUTEXES
 486
 487 config RT_MUTEX_TESTER
 488         bool "Built-in scriptable tester for rt-mutexes"
 489         depends on DEBUG_KERNEL && RT_MUTEXES
 490         help
 491           This option enables a rt-mutex tester.
 492
 493 config DEBUG_SPINLOCK
 494         bool "Spinlock and rw-lock debugging: basic checks"
 495         depends on DEBUG_KERNEL
 496         help
 497           Say Y here and build SMP to catch missing spinlock initialization
 498           and certain other kinds of spinlock errors commonly made.  This is
 499           best used in conjunction with the NMI watchdog so that spinlock
 500           deadlocks are also debuggable.
 501
 502 config DEBUG_MUTEXES
 503         bool "Mutex debugging: basic checks"
 504         depends on DEBUG_KERNEL
 505         help
 506          This feature allows mutex semantics violations to be detected and
 507          reported.
 508
 509 config DEBUG_LOCK_ALLOC
 510         bool "Lock debugging: detect incorrect freeing of live locks"
 511         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 512         select DEBUG_SPINLOCK
 513         select DEBUG_MUTEXES
 514         select LOCKDEP
 515         help
 516          This feature will check whether any held lock (spinlock, rwlock,
 517          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 518          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 519          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 520          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 521          held during task exit.
 522
 523 config PROVE_LOCKING
 524         bool "Lock debugging: prove locking correctness"
 525         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 526         select LOCKDEP
 527         select DEBUG_SPINLOCK
 528         select DEBUG_MUTEXES
 529         select DEBUG_LOCK_ALLOC
 530         select TRACE_IRQFLAGS
 531         default n
 532         help
 533          This feature enables the kernel to prove that all locking
 534          that occurs in the kernel runtime is mathematically
 535          correct: that under no circumstance could an arbitrary (and
 536          not yet triggered) combination of observed locking
 537          sequences (on an arbitrary number of CPUs, running an
 538          arbitrary number of tasks and interrupt contexts) cause a
 539          deadlock.
 540
 541          In short, this feature enables the kernel to report locking
 542          related deadlocks before they actually occur.
 543
 544          The proof does not depend on how hard and complex a
 545          deadlock scenario would be to trigger: how many
 546          participant CPUs, tasks and irq-contexts would be needed
 547          for it to trigger. The proof also does not depend on
 548          timing: if a race and a resulting deadlock is possible
 549          theoretically (no matter how unlikely the race scenario
 550          is), it will be proven so and will immediately be
 551          reported by the kernel (once the event is observed that
 552          makes the deadlock theoretically possible).
 553
 554          If a deadlock is impossible (i.e. the locking rules, as
 555          observed by the kernel, are mathematically correct), the
 556          kernel reports nothing.
 557
 558          NOTE: this feature can also be enabled for rwlocks, mutexes
 559          and rwsems - in which case all dependencies between these
 560          different locking variants are observed and mapped too, and
 561          the proof of observed correctness is also maintained for an
 562          arbitrary combination of these separate locking variants.
 563
 564          For more details, see Documentation/lockdep-design.txt.
 565
 566 config PROVE_RCU
 567         bool "RCU debugging: prove RCU correctness"
 568         depends on PROVE_LOCKING
 569         default n
 570         help
 571          This feature enables lockdep extensions that check for correct
 572          use of RCU APIs.  This is currently under development.  Say Y
 573          if you want to debug RCU usage or help work on the PROVE_RCU
 574          feature.
 575
 576          Say N if you are unsure.
 577
 578 config PROVE_RCU_REPEATEDLY
 579         bool "RCU debugging: don't disable PROVE_RCU on first splat"
 580         depends on PROVE_RCU
 581         default n
 582         help
 583          By itself, PROVE_RCU will disable checking upon issuing the
 584          first warning (or "splat").  This feature prevents such
 585          disabling, allowing multiple RCU-lockdep warnings to be printed
 586          on a single reboot.
 587
 588          Say Y to allow multiple RCU-lockdep warnings per boot.
 589
 590          Say N if you are unsure.
 591
 592 config SPARSE_RCU_POINTER
 593         bool "RCU debugging: sparse-based checks for pointer usage"
 594         default n
 595         help
 596          This feature enables the __rcu sparse annotation for
 597          RCU-protected pointers.  This annotation will cause sparse
 598          to flag any non-RCU used of annotated pointers.  This can be
 599          helpful when debugging RCU usage.  Please note that this feature
 600          is not intended to enforce code cleanliness; it is instead merely
 601          a debugging aid.
 602
 603          Say Y to make sparse flag questionable use of RCU-protected pointers
 604
 605          Say N if you are unsure.
 606
 607 config LOCKDEP
 608         bool
 609         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 610         select STACKTRACE
 611         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 612         select KALLSYMS
 613         select KALLSYMS_ALL
 614
 615 config LOCK_STAT
 616         bool "Lock usage statistics"
 617         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 618         select LOCKDEP
 619         select DEBUG_SPINLOCK
 620         select DEBUG_MUTEXES
 621         select DEBUG_LOCK_ALLOC
 622         default n
 623         help
 624          This feature enables tracking lock contention points
 625
 626          For more details, see Documentation/lockstat.txt
 627
 628          This also enables lock events required by "perf lock",
 629          subcommand of perf.
 630          If you want to use "perf lock", you also need to turn on
 631          CONFIG_EVENT_TRACING.
 632
 633          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 634          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 635
 636 config DEBUG_LOCKDEP
 637         bool "Lock dependency engine debugging"
 638         depends on DEBUG_KERNEL && LOCKDEP
 639         help
 640           If you say Y here, the lock dependency engine will do
 641           additional runtime checks to debug itself, at the price
 642           of more runtime overhead.
 643
 644 config TRACE_IRQFLAGS
 645         bool
 646         help
 647           Enables hooks to interrupt enabling and disabling for
 648           either tracing or lock debugging.
 649
 650 config DEBUG_SPINLOCK_SLEEP
 651         bool "Spinlock debugging: sleep-inside-spinlock checking"
 652         depends on DEBUG_KERNEL
 653         help
 654           If you say Y here, various routines which may sleep will become very
 655           noisy if they are called with a spinlock held.
 656
 657 config DEBUG_LOCKING_API_SELFTESTS
 658         bool "Locking API boot-time self-tests"
 659         depends on DEBUG_KERNEL
 660         help
 661           Say Y here if you want the kernel to run a short self-test during
 662           bootup. The self-test checks whether common types of locking bugs
 663           are detected by debugging mechanisms or not. (if you disable
 664           lock debugging then those bugs wont be detected of course.)
 665           The following locking APIs are covered: spinlocks, rwlocks,
 666           mutexes and rwsems.
 667
 668 config STACKTRACE
 669         bool
 670         depends on STACKTRACE_SUPPORT
 671
 672 config DEBUG_KOBJECT
 673         bool "kobject debugging"
 674         depends on DEBUG_KERNEL
 675         help
 676           If you say Y here, some extra kobject debugging messages will be sent
 677           to the syslog.
 678
 679 config DEBUG_HIGHMEM
 680         bool "Highmem debugging"
 681         depends on DEBUG_KERNEL && HIGHMEM
 682         help
 683           This options enables addition error checking for high memory systems.
 684           Disable for production systems.
 685
 686 config DEBUG_BUGVERBOSE
 687         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
 688         depends on BUG
 689         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 690                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 691         default y
 692         help
 693           Say Y here to make BUG() panics output the file name and line number
 694           of the BUG call as well as the EIP and oops trace.  This aids
 695           debugging but costs about 70-100K of memory.
 696
 697 config DEBUG_INFO
 698         bool "Compile the kernel with debug info"
 699         depends on DEBUG_KERNEL
 700         help
 701           If you say Y here the resulting kernel image will include
 702           debugging info resulting in a larger kernel image.
 703           This adds debug symbols to the kernel and modules (gcc -g), and
 704           is needed if you intend to use kernel crashdump or binary object
 705           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 706           Say Y here only if you plan to debug the kernel.
 707
 708           If unsure, say N.
 709
 710 config DEBUG_INFO_REDUCED
 711         bool "Reduce debugging information"
 712         depends on DEBUG_INFO
 713         help
 714           If you say Y here gcc is instructed to generate less debugging
 715           information for structure types. This means that tools that
 716           need full debugging information (like kgdb or systemtap) won't
 717           be happy. But if you merely need debugging information to
 718           resolve line numbers there is no loss. Advantage is that
 719           build directory object sizes shrink dramatically over a full
 720           DEBUG_INFO build and compile times are reduced too.
 721           Only works with newer gcc versions.
 722
 723 config DEBUG_VM
 724         bool "Debug VM"
 725         depends on DEBUG_KERNEL
 726         help
 727           Enable this to turn on extended checks in the virtual-memory system
 728           that may impact performance.
 729
 730           If unsure, say N.
 731
 732 config DEBUG_VIRTUAL
 733         bool "Debug VM translations"
 734         depends on DEBUG_KERNEL && X86
 735         help
 736           Enable some costly sanity checks in virtual to page code. This can
 737           catch mistakes with virt_to_page() and friends.
 738
 739           If unsure, say N.
 740
 741 config DEBUG_NOMMU_REGIONS
 742         bool "Debug the global anon/private NOMMU mapping region tree"
 743         depends on DEBUG_KERNEL && !MMU
 744         help
 745           This option causes the global tree of anonymous and private mapping
 746           regions to be regularly checked for invalid topology.
 747
 748 config DEBUG_WRITECOUNT
 749         bool "Debug filesystem writers count"
 750         depends on DEBUG_KERNEL
 751         help
 752           Enable this to catch wrong use of the writers count in struct
 753           vfsmount.  This will increase the size of each file struct by
 754           32 bits.
 755
 756           If unsure, say N.
 757
 758 config DEBUG_MEMORY_INIT
 759         bool "Debug memory initialisation" if EXPERT
 760         default !EXPERT
 761         help
 762           Enable this for additional checks during memory initialisation.
 763           The sanity checks verify aspects of the VM such as the memory model
 764           and other information provided by the architecture. Verbose
 765           information will be printed at KERN_DEBUG loglevel depending
 766           on the mminit_loglevel= command-line option.
 767
 768           If unsure, say Y
 769
 770 config DEBUG_LIST
 771         bool "Debug linked list manipulation"
 772         depends on DEBUG_KERNEL
 773         help
 774           Enable this to turn on extended checks in the linked-list
 775           walking routines.
 776
 777           If unsure, say N.
 778
 779 config TEST_LIST_SORT
 780         bool "Linked list sorting test"
 781         depends on DEBUG_KERNEL
 782         help
 783           Enable this to turn on 'list_sort()' function test. This test is
 784           executed only once during system boot, so affects only boot time.
 785
 786           If unsure, say N.
 787
 788 config DEBUG_SG
 789         bool "Debug SG table operations"
 790         depends on DEBUG_KERNEL
 791         help
 792           Enable this to turn on checks on scatter-gather tables. This can
 793           help find problems with drivers that do not properly initialize
 794           their sg tables.
 795
 796           If unsure, say N.
 797
 798 config DEBUG_NOTIFIERS
 799         bool "Debug notifier call chains"
 800         depends on DEBUG_KERNEL
 801         help
 802           Enable this to turn on sanity checking for notifier call chains.
 803           This is most useful for kernel developers to make sure that
 804           modules properly unregister themselves from notifier chains.
 805           This is a relatively cheap check but if you care about maximum
 806           performance, say N.
 807
 808 config DEBUG_CREDENTIALS
 809         bool "Debug credential management"
 810         depends on DEBUG_KERNEL
 811         help
 812           Enable this to turn on some debug checking for credential
 813           management.  The additional code keeps track of the number of
 814           pointers from task_structs to any given cred struct, and checks to
 815           see that this number never exceeds the usage count of the cred
 816           struct.
 817
 818           Furthermore, if SELinux is enabled, this also checks that the
 819           security pointer in the cred struct is never seen to be invalid.
 820
 821           If unsure, say N.
 822
 823 #
 824 # Select this config option from the architecture Kconfig, if it
 825 # it is preferred to always offer frame pointers as a config
 826 # option on the architecture (regardless of KERNEL_DEBUG):
 827 #
 828 config ARCH_WANT_FRAME_POINTERS
 829         bool
 830         help
 831
 832 config FRAME_POINTER
 833         bool "Compile the kernel with frame pointers"
 834         depends on DEBUG_KERNEL && \
 835                 (CRIS || M68K || FRV || UML || \
 836                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 837                 ARCH_WANT_FRAME_POINTERS
 838         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 839         help
 840           If you say Y here the resulting kernel image will be slightly
 841           larger and slower, but it gives very useful debugging information
 842           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 843
 844 config BOOT_PRINTK_DELAY
 845         bool "Delay each boot printk message by N milliseconds"
 846         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 847         help
 848           This build option allows you to read kernel boot messages
 849           by inserting a short delay after each one.  The delay is
 850           specified in milliseconds on the kernel command line,
 851           using "boot_delay=N".
 852
 853           It is likely that you would also need to use "lpj=M" to preset
 854           the "loops per jiffie" value.
 855           See a previous boot log for the "lpj" value to use for your
 856           system, and then set "lpj=M" before setting "boot_delay=N".
 857           NOTE:  Using this option may adversely affect SMP systems.
 858           I.e., processors other than the first one may not boot up.
 859           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 860           what it believes to be lockup conditions.
 861
 862 config RCU_TORTURE_TEST
 863         tristate "torture tests for RCU"
 864         depends on DEBUG_KERNEL
 865         default n
 866         help
 867           This option provides a kernel module that runs torture tests
 868           on the RCU infrastructure.  The kernel module may be built
 869           after the fact on the running kernel to be tested, if desired.
 870
 871           Say Y here if you want RCU torture tests to be built into
 872           the kernel.
 873           Say M if you want the RCU torture tests to build as a module.
 874           Say N if you are unsure.
 875
 876 config RCU_TORTURE_TEST_RUNNABLE
 877         bool "torture tests for RCU runnable by default"
 878         depends on RCU_TORTURE_TEST = y
 879         default n
 880         help
 881           This option provides a way to build the RCU torture tests
 882           directly into the kernel without them starting up at boot
 883           time.  You can use /proc/sys/kernel/rcutorture_runnable
 884           to manually override this setting.  This /proc file is
 885           available only when the RCU torture tests have been built
 886           into the kernel.
 887
 888           Say Y here if you want the RCU torture tests to start during
 889           boot (you probably don't).
 890           Say N here if you want the RCU torture tests to start only
 891           after being manually enabled via /proc.
 892
 893 config RCU_CPU_STALL_DETECTOR
 894         bool "Check for stalled CPUs delaying RCU grace periods"
 895         depends on TREE_RCU || TREE_PREEMPT_RCU
 896         default y
 897         help
 898           This option causes RCU to printk information on which
 899           CPUs are delaying the current grace period, but only when
 900           the grace period extends for excessive time periods.
 901
 902           Say N if you want to disable such checks.
 903
 904           Say Y if you are unsure.
 905
 906 config RCU_CPU_STALL_TIMEOUT
 907         int "RCU CPU stall timeout in seconds"
 908         depends on RCU_CPU_STALL_DETECTOR
 909         range 3 300
 910         default 60
 911         help
 912           If a given RCU grace period extends more than the specified
 913           number of seconds, a CPU stall warning is printed.  If the
 914           RCU grace period persists, additional CPU stall warnings are
 915           printed at more widely spaced intervals.
 916
 917 config RCU_CPU_STALL_DETECTOR_RUNNABLE
 918         bool "RCU CPU stall checking starts automatically at boot"
 919         depends on RCU_CPU_STALL_DETECTOR
 920         default y
 921         help
 922           If set, start checking for RCU CPU stalls immediately on
 923           boot.  Otherwise, RCU CPU stall checking must be manually
 924           enabled.
 925
 926           Say Y if you are unsure.
 927
 928           Say N if you wish to suppress RCU CPU stall checking during boot.
 929
 930 config RCU_CPU_STALL_VERBOSE
 931         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 932         depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
 933         default y
 934         help
 935           This option causes RCU to printk detailed per-task information
 936           for any tasks that are stalling the current RCU grace period.
 937
 938           Say N if you are unsure.
 939
 940           Say Y if you want to enable such checks.
 941
 942 config KPROBES_SANITY_TEST
 943         bool "Kprobes sanity tests"
 944         depends on DEBUG_KERNEL
 945         depends on KPROBES
 946         default n
 947         help
 948           This option provides for testing basic kprobes functionality on
 949           boot. A sample kprobe, jprobe and kretprobe are inserted and
 950           verified for functionality.
 951
 952           Say N if you are unsure.
 953
 954 config BACKTRACE_SELF_TEST
 955         tristate "Self test for the backtrace code"
 956         depends on DEBUG_KERNEL
 957         default n
 958         help
 959           This option provides a kernel module that can be used to test
 960           the kernel stack backtrace code. This option is not useful
 961           for distributions or general kernels, but only for kernel
 962           developers working on architecture code.
 963
 964           Note that if you want to also test saved backtraces, you will
 965           have to enable STACKTRACE as well.
 966
 967           Say N if you are unsure.
 968
 969 config DEBUG_BLOCK_EXT_DEVT
 970         bool "Force extended block device numbers and spread them"
 971         depends on DEBUG_KERNEL
 972         depends on BLOCK
 973         default n
 974         help
 975           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 976           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 977           YOU ARE DOING.  Distros, please enable this and fix whatever
 978           is broken.
 979
 980           Conventionally, block device numbers are allocated from
 981           predetermined contiguous area.  However, extended block area
 982           may introduce non-contiguous block device numbers.  This
 983           option forces most block device numbers to be allocated from
 984           the extended space and spreads them to discover kernel or
 985           userland code paths which assume predetermined contiguous
 986           device number allocation.
 987
 988           Note that turning on this debug option shuffles all the
 989           device numbers for all IDE and SCSI devices including libata
 990           ones, so root partition specified using device number
 991           directly (via rdev or root=MAJ:MIN) won't work anymore.
 992           Textual device names (root=/dev/sdXn) will continue to work.
 993
 994           Say N if you are unsure.
 995
 996 config DEBUG_FORCE_WEAK_PER_CPU
 997         bool "Force weak per-cpu definitions"
 998         depends on DEBUG_KERNEL
 999         help
1000           s390 and alpha require percpu variables in modules to be
1001           defined weak to work around addressing range issue which
1002           puts the following two restrictions on percpu variable
1003           definitions.
1004
1005           1. percpu symbols must be unique whether static or not
1006           2. percpu variables can't be defined inside a function
1007
1008           To ensure that generic code follows the above rules, this
1009           option forces all percpu variables to be defined as weak.
1010
1011 config LKDTM
1012         tristate "Linux Kernel Dump Test Tool Module"
1013         depends on DEBUG_FS
1014         depends on BLOCK
1015         default n
1016         help
1017         This module enables testing of the different dumping mechanisms by
1018         inducing system failures at predefined crash points.
1019         If you don't need it: say N
1020         Choose M here to compile this code as a module. The module will be
1021         called lkdtm.
1022
1023         Documentation on how to use the module can be found in
1024         Documentation/fault-injection/provoke-crashes.txt
1025
1026 config CPU_NOTIFIER_ERROR_INJECT
1027         tristate "CPU notifier error injection module"
1028         depends on HOTPLUG_CPU && DEBUG_KERNEL
1029         help
1030           This option provides a kernel module that can be used to test
1031           the error handling of the cpu notifiers
1032
1033           To compile this code as a module, choose M here: the module will
1034           be called cpu-notifier-error-inject.
1035
1036           If unsure, say N.
1037
1038 config FAULT_INJECTION
1039         bool "Fault-injection framework"
1040         depends on DEBUG_KERNEL
1041         help
1042           Provide fault-injection framework.
1043           For more details, see Documentation/fault-injection/.
1044
1045 config FAILSLAB
1046         bool "Fault-injection capability for kmalloc"
1047         depends on FAULT_INJECTION
1048         depends on SLAB || SLUB
1049         help
1050           Provide fault-injection capability for kmalloc.
1051
1052 config FAIL_PAGE_ALLOC
1053         bool "Fault-injection capabilitiy for alloc_pages()"
1054         depends on FAULT_INJECTION
1055         help
1056           Provide fault-injection capability for alloc_pages().
1057
1058 config FAIL_MAKE_REQUEST
1059         bool "Fault-injection capability for disk IO"
1060         depends on FAULT_INJECTION && BLOCK
1061         help
1062           Provide fault-injection capability for disk IO.
1063
1064 config FAIL_IO_TIMEOUT
1065         bool "Fault-injection capability for faking disk interrupts"
1066         depends on FAULT_INJECTION && BLOCK
1067         help
1068           Provide fault-injection capability on end IO handling. This
1069           will make the block layer "forget" an interrupt as configured,
1070           thus exercising the error handling.
1071
1072           Only works with drivers that use the generic timeout handling,
1073           for others it wont do anything.
1074
1075 config FAULT_INJECTION_DEBUG_FS
1076         bool "Debugfs entries for fault-injection capabilities"
1077         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1078         help
1079           Enable configuration of fault-injection capabilities via debugfs.
1080
1081 config FAULT_INJECTION_STACKTRACE_FILTER
1082         bool "stacktrace filter for fault-injection capabilities"
1083         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1084         depends on !X86_64
1085         select STACKTRACE
1086         select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
1087         help
1088           Provide stacktrace filter for fault-injection capabilities
1089
1090 config LATENCYTOP
1091         bool "Latency measuring infrastructure"
1092         depends on HAVE_LATENCYTOP_SUPPORT
1093         depends on DEBUG_KERNEL
1094         depends on STACKTRACE_SUPPORT
1095         depends on PROC_FS
1096         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
1097         select KALLSYMS
1098         select KALLSYMS_ALL
1099         select STACKTRACE
1100         select SCHEDSTATS
1101         select SCHED_DEBUG
1102         help
1103           Enable this option if you want to use the LatencyTOP tool
1104           to find out which userspace is blocking on what kernel operations.
1105
1106 config SYSCTL_SYSCALL_CHECK
1107         bool "Sysctl checks"
1108         depends on SYSCTL
1109         ---help---
1110           sys_sysctl uses binary paths that have been found challenging
1111           to properly maintain and use. This enables checks that help
1112           you to keep things correct.
1113
1114 source mm/Kconfig.debug
1115 source kernel/trace/Kconfig
1116
1117 config PROVIDE_OHCI1394_DMA_INIT
1118         bool "Remote debugging over FireWire early on boot"
1119         depends on PCI && X86
1120         help
1121           If you want to debug problems which hang or crash the kernel early
1122           on boot and the crashing machine has a FireWire port, you can use
1123           this feature to remotely access the memory of the crashed machine
1124           over FireWire. This employs remote DMA as part of the OHCI1394
1125           specification which is now the standard for FireWire controllers.
1126
1127           With remote DMA, you can monitor the printk buffer remotely using
1128           firescope and access all memory below 4GB using fireproxy from gdb.
1129           Even controlling a kernel debugger is possible using remote DMA.
1130
1131           Usage:
1132
1133           If ohci1394_dma=early is used as boot parameter, it will initialize
1134           all OHCI1394 controllers which are found in the PCI config space.
1135
1136           As all changes to the FireWire bus such as enabling and disabling
1137           devices cause a bus reset and thereby disable remote DMA for all
1138           devices, be sure to have the cable plugged and FireWire enabled on
1139           the debugging host before booting the debug target for debugging.
1140
1141           This code (~1k) is freed after boot. By then, the firewire stack
1142           in charge of the OHCI-1394 controllers should be used instead.
1143
1144           See Documentation/debugging-via-ohci1394.txt for more information.
1145
1146 config FIREWIRE_OHCI_REMOTE_DMA
1147         bool "Remote debugging over FireWire with firewire-ohci"
1148         depends on FIREWIRE_OHCI
1149         help
1150           This option lets you use the FireWire bus for remote debugging
1151           with help of the firewire-ohci driver. It enables unfiltered
1152           remote DMA in firewire-ohci.
1153           See Documentation/debugging-via-ohci1394.txt for more information.
1154
1155           If unsure, say N.
1156
1157 config BUILD_DOCSRC
1158         bool "Build targets in Documentation/ tree"
1159         depends on HEADERS_CHECK
1160         help
1161           This option attempts to build objects from the source files in the
1162           kernel Documentation/ tree.
1163
1164           Say N if you are unsure.
1165
1166 config DYNAMIC_DEBUG
1167         bool "Enable dynamic printk() support"
1168         default n
1169         depends on PRINTK
1170         depends on DEBUG_FS
1171         help
1172
1173           Compiles debug level messages into the kernel, which would not
1174           otherwise be available at runtime. These messages can then be
1175           enabled/disabled based on various levels of scope - per source file,
1176           function, module, format string, and line number. This mechanism
1177           implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1178           this compile option is a larger kernel text size of about 2%.
1179
1180           Usage:
1181
1182           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1183           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1184           filesystem must first be mounted before making use of this feature.
1185           We refer the control file as: <debugfs>/dynamic_debug/control. This
1186           file contains a list of the debug statements that can be enabled. The
1187           format for each line of the file is:
1188
1189                 filename:lineno [module]function flags format
1190
1191           filename : source file of the debug statement
1192           lineno : line number of the debug statement
1193           module : module that contains the debug statement
1194           function : function that contains the debug statement
1195           flags : 'p' means the line is turned 'on' for printing
1196           format : the format used for the debug statement
1197
1198           From a live system:
1199
1200                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1201                 # filename:lineno [module]function flags format
1202                 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1203                 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1204                 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1205
1206           Example usage:
1207
1208                 // enable the message at line 1603 of file svcsock.c
1209                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1210                                                 <debugfs>/dynamic_debug/control
1211
1212                 // enable all the messages in file svcsock.c
1213                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1214                                                 <debugfs>/dynamic_debug/control
1215
1216                 // enable all the messages in the NFS server module
1217                 nullarbor:~ # echo -n 'module nfsd +p' >
1218                                                 <debugfs>/dynamic_debug/control
1219
1220                 // enable all 12 messages in the function svc_process()
1221                 nullarbor:~ # echo -n 'func svc_process +p' >
1222                                                 <debugfs>/dynamic_debug/control
1223
1224                 // disable all 12 messages in the function svc_process()
1225                 nullarbor:~ # echo -n 'func svc_process -p' >
1226                                                 <debugfs>/dynamic_debug/control
1227
1228           See Documentation/dynamic-debug-howto.txt for additional information.
1229
1230 config DMA_API_DEBUG
1231         bool "Enable debugging of DMA-API usage"
1232         depends on HAVE_DMA_API_DEBUG
1233         help
1234           Enable this option to debug the use of the DMA API by device drivers.
1235           With this option you will be able to detect common bugs in device
1236           drivers like double-freeing of DMA mappings or freeing mappings that
1237           were never allocated.
1238           This option causes a performance degredation.  Use only if you want
1239           to debug device drivers. If unsure, say N.
1240
1241 config ATOMIC64_SELFTEST
1242         bool "Perform an atomic64_t self-test at boot"
1243         help
1244           Enable this option to test the atomic64_t functions at boot.
1245
1246           If unsure, say N.
1247
1248 config ASYNC_RAID6_TEST
1249         tristate "Self test for hardware accelerated raid6 recovery"
1250         depends on ASYNC_RAID6_RECOV
1251         select ASYNC_MEMCPY
1252         ---help---
1253           This is a one-shot self test that permutes through the
1254           recovery of all the possible two disk failure scenarios for a
1255           N-disk array.  Recovery is performed with the asynchronous
1256           raid6 recovery routines, and will optionally use an offload
1257           engine if one is available.
1258
1259           If unsure, say N.
1260
1261 source "samples/Kconfig"
1262
1263 source "lib/Kconfig.kgdb"
1264
1265 source "lib/Kconfig.kmemcheck"
1266
1267 config TEST_KSTRTOX
1268         tristate "Test kstrto*() family of functions at runtime"