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.  Or add printk.time=1 at boot-time.
  11           See Documentation/kernel-parameters.txt
  12
  13 config DEFAULT_MESSAGE_LOGLEVEL
  14         int "Default message log level (1-7)"
  15         range 1 7
  16         default "4"
  17         help
  18           Default log level for printk statements with no specified priority.
  19
  20           This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
  21           that are auditing their logs closely may want to set it to a lower
  22           priority.
  23
  24 config ENABLE_WARN_DEPRECATED
  25         bool "Enable __deprecated logic"
  26         default y
  27         help
  28           Enable the __deprecated logic in the kernel build.
  29           Disable this to suppress the "warning: 'foo' is deprecated
  30           (declared at kernel/power/somefile.c:1234)" messages.
  31
  32 config ENABLE_MUST_CHECK
  33         bool "Enable __must_check logic"
  34         default y
  35         help
  36           Enable the __must_check logic in the kernel build.  Disable this to
  37           suppress the "warning: ignoring return value of 'foo', declared with
  38           attribute warn_unused_result" messages.
  39
  40 config FRAME_WARN
  41         int "Warn for stack frames larger than (needs gcc 4.4)"
  42         range 0 8192
  43         default 1024 if !64BIT
  44         default 2048 if 64BIT
  45         help
  46           Tell gcc to warn at build time for stack frames larger than this.
  47           Setting this too low will cause a lot of warnings.
  48           Setting it to 0 disables the warning.
  49           Requires gcc 4.4
  50
  51 config MAGIC_SYSRQ
  52         bool "Magic SysRq key"
  53         depends on !UML
  54         help
  55           If you say Y here, you will have some control over the system even
  56           if the system crashes for example during kernel debugging (e.g., you
  57           will be able to flush the buffer cache to disk, reboot the system
  58           immediately or dump some status information). This is accomplished
  59           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  60           also works on a serial console (on PC hardware at least), if you
  61           send a BREAK and then within 5 seconds a command keypress. The
  62           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  63           unless you really know what this hack does.
  64
  65 config STRIP_ASM_SYMS
  66         bool "Strip assembler-generated symbols during link"
  67         default n
  68         help
  69           Strip internal assembler-generated symbols during a link (symbols
  70           that look like '.Lxxx') so they don't pollute the output of
  71           get_wchan() and suchlike.
  72
  73 config UNUSED_SYMBOLS
  74         bool "Enable unused/obsolete exported symbols"
  75         default y if X86
  76         help
  77           Unused but exported symbols make the kernel needlessly bigger.  For
  78           that reason most of these unused exports will soon be removed.  This
  79           option is provided temporarily to provide a transition period in case
  80           some external kernel module needs one of these symbols anyway. If you
  81           encounter such a case in your module, consider if you are actually
  82           using the right API.  (rationale: since nobody in the kernel is using
  83           this in a module, there is a pretty good chance it's actually the
  84           wrong interface to use).  If you really need the symbol, please send a
  85           mail to the linux kernel mailing list mentioning the symbol and why
  86           you really need it, and what the merge plan to the mainline kernel for
  87           your module is.
  88
  89 config DEBUG_FS
  90         bool "Debug Filesystem"
  91         help
  92           debugfs is a virtual file system that kernel developers use to put
  93           debugging files into.  Enable this option to be able to read and
  94           write to these files.
  95
  96           For detailed documentation on the debugfs API, see
  97           Documentation/DocBook/filesystems.
  98
  99           If unsure, say N.
 100
 101 config HEADERS_CHECK
 102         bool "Run 'make headers_check' when building vmlinux"
 103         depends on !UML
 104         help
 105           This option will extract the user-visible kernel headers whenever
 106           building the kernel, and will run basic sanity checks on them to
 107           ensure that exported files do not attempt to include files which
 108           were not exported, etc.
 109
 110           If you're making modifications to header files which are
 111           relevant for userspace, say 'Y', and check the headers
 112           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 113           your build tree), to make sure they're suitable.
 114
 115 config DEBUG_SECTION_MISMATCH
 116         bool "Enable full Section mismatch analysis"
 117         help
 118           The section mismatch analysis checks if there are illegal
 119           references from one section to another section.
 120           During linktime or runtime, some sections are dropped;
 121           any use of code/data previously in these sections would
 122           most likely result in an oops.
 123           In the code, functions and variables are annotated with
 124           __init, __devinit, etc. (see the full list in include/linux/init.h),
 125           which results in the code/data being placed in specific sections.
 126           The section mismatch analysis is always performed after a full
 127           kernel build, and enabling this option causes the following
 128           additional steps to occur:
 129           - Add the option -fno-inline-functions-called-once to gcc commands.
 130             When inlining a function annotated with __init in a non-init
 131             function, we would lose the section information and thus
 132             the analysis would not catch the illegal reference.
 133             This option tells gcc to inline less (but it does result in
 134             a larger kernel).
 135           - Run the section mismatch analysis for each module/built-in.o file.
 136             When we run the section mismatch analysis on vmlinux.o, we
 137             lose valueble information about where the mismatch was
 138             introduced.
 139             Running the analysis for each module/built-in.o file
 140             tells where the mismatch happens much closer to the
 141             source. The drawback is that the same mismatch is
 142             reported at least twice.
 143           - Enable verbose reporting from modpost in order to help resolve
 144             the section mismatches that are reported.
 145
 146 config DEBUG_KERNEL
 147         bool "Kernel debugging"
 148         help
 149           Say Y here if you are developing drivers or trying to debug and
 150           identify kernel problems.
 151
 152 config DEBUG_SHIRQ
 153         bool "Debug shared IRQ handlers"
 154         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 155         help
 156           Enable this to generate a spurious interrupt as soon as a shared
 157           interrupt handler is registered, and just before one is deregistered.
 158           Drivers ought to be able to handle interrupts coming in at those
 159           points; some don't and need to be caught.
 160
 161 config LOCKUP_DETECTOR
 162         bool "Detect Hard and Soft Lockups"
 163         depends on DEBUG_KERNEL && !S390
 164         help
 165           Say Y here to enable the kernel to act as a watchdog to detect
 166           hard and soft lockups.
 167
 168           Softlockups are bugs that cause the kernel to loop in kernel
 169           mode for more than 60 seconds, without giving other tasks a
 170           chance to run.  The current stack trace is displayed upon
 171           detection and the system will stay locked up.
 172
 173           Hardlockups are bugs that cause the CPU to loop in kernel mode
 174           for more than 60 seconds, without letting other interrupts have a
 175           chance to run.  The current stack trace is displayed upon detection
 176           and the system will stay locked up.
 177
 178           The overhead should be minimal.  A periodic hrtimer runs to
 179           generate interrupts and kick the watchdog task every 10-12 seconds.
 180           An NMI is generated every 60 seconds or so to check for hardlockups.
 181
 182 config HARDLOCKUP_DETECTOR
 183         def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
 184                  !ARCH_HAS_NMI_WATCHDOG
 185
 186 config BOOTPARAM_HARDLOCKUP_PANIC
 187         bool "Panic (Reboot) On Hard Lockups"
 188         depends on LOCKUP_DETECTOR
 189         help
 190           Say Y here to enable the kernel to panic on "hard lockups",
 191           which are bugs that cause the kernel to loop in kernel
 192           mode with interrupts disabled for more than 60 seconds.
 193
 194           Say N if unsure.
 195
 196 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
 197         int
 198         depends on LOCKUP_DETECTOR
 199         range 0 1
 200         default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
 201         default 1 if BOOTPARAM_HARDLOCKUP_PANIC
 202
 203 config BOOTPARAM_SOFTLOCKUP_PANIC
 204         bool "Panic (Reboot) On Soft Lockups"
 205         depends on LOCKUP_DETECTOR
 206         help
 207           Say Y here to enable the kernel to panic on "soft lockups",
 208           which are bugs that cause the kernel to loop in kernel
 209           mode for more than 60 seconds, without giving other tasks a
 210           chance to run.
 211
 212           The panic can be used in combination with panic_timeout,
 213           to cause the system to reboot automatically after a
 214           lockup has been detected. This feature is useful for
 215           high-availability systems that have uptime guarantees and
 216           where a lockup must be resolved ASAP.
 217
 218           Say N if unsure.
 219
 220 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 221         int
 222         depends on LOCKUP_DETECTOR
 223         range 0 1
 224         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 225         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 226
 227 config DETECT_HUNG_TASK
 228         bool "Detect Hung Tasks"
 229         depends on DEBUG_KERNEL
 230         default LOCKUP_DETECTOR
 231         help
 232           Say Y here to enable the kernel to detect "hung tasks",
 233           which are bugs that cause the task to be stuck in
 234           uninterruptible "D" state indefinitiley.
 235
 236           When a hung task is detected, the kernel will print the
 237           current stack trace (which you should report), but the
 238           task will stay in uninterruptible state. If lockdep is
 239           enabled then all held locks will also be reported. This
 240           feature has negligible overhead.
 241
 242 config DEFAULT_HUNG_TASK_TIMEOUT
 243         int "Default timeout for hung task detection (in seconds)"
 244         depends on DETECT_HUNG_TASK
 245         default 120
 246         help
 247           This option controls the default timeout (in seconds) used
 248           to determine when a task has become non-responsive and should
 249           be considered hung.
 250
 251           It can be adjusted at runtime via the kernel.hung_task_timeout_secs
 252           sysctl or by writing a value to
 253           /proc/sys/kernel/hung_task_timeout_secs.
 254
 255           A timeout of 0 disables the check.  The default is two minutes.
 256           Keeping the default should be fine in most cases.
 257
 258 config BOOTPARAM_HUNG_TASK_PANIC
 259         bool "Panic (Reboot) On Hung Tasks"
 260         depends on DETECT_HUNG_TASK
 261         help
 262           Say Y here to enable the kernel to panic on "hung tasks",
 263           which are bugs that cause the kernel to leave a task stuck
 264           in uninterruptible "D" state.
 265
 266           The panic can be used in combination with panic_timeout,
 267           to cause the system to reboot automatically after a
 268           hung task has been detected. This feature is useful for
 269           high-availability systems that have uptime guarantees and
 270           where a hung tasks must be resolved ASAP.
 271
 272           Say N if unsure.
 273
 274 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 275         int
 276         depends on DETECT_HUNG_TASK
 277         range 0 1
 278         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 279         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 280
 281 config SCHED_DEBUG
 282         bool "Collect scheduler debugging info"
 283         depends on DEBUG_KERNEL && PROC_FS
 284         default y
 285         help
 286           If you say Y here, the /proc/sched_debug file will be provided
 287           that can help debug the scheduler. The runtime overhead of this
 288           option is minimal.
 289
 290 config SCHEDSTATS
 291         bool "Collect scheduler statistics"
 292         depends on DEBUG_KERNEL && PROC_FS
 293         help
 294           If you say Y here, additional code will be inserted into the
 295           scheduler and related routines to collect statistics about
 296           scheduler behavior and provide them in /proc/schedstat.  These
 297           stats may be useful for both tuning and debugging the scheduler
 298           If you aren't debugging the scheduler or trying to tune a specific
 299           application, you can say N to avoid the very slight overhead
 300           this adds.
 301
 302 config TIMER_STATS
 303         bool "Collect kernel timers statistics"
 304         depends on DEBUG_KERNEL && PROC_FS
 305         help
 306           If you say Y here, additional code will be inserted into the
 307           timer routines to collect statistics about kernel timers being
 308           reprogrammed. The statistics can be read from /proc/timer_stats.
 309           The statistics collection is started by writing 1 to /proc/timer_stats,
 310           writing 0 stops it. This feature is useful to collect information
 311           about timer usage patterns in kernel and userspace. This feature
 312           is lightweight if enabled in the kernel config but not activated
 313           (it defaults to deactivated on bootup and will only be activated
 314           if some application like powertop activates it explicitly).
 315
 316 config DEBUG_OBJECTS
 317         bool "Debug object operations"
 318         depends on DEBUG_KERNEL
 319         help
 320           If you say Y here, additional code will be inserted into the
 321           kernel to track the life time of various objects and validate
 322           the operations on those objects.
 323
 324 config DEBUG_OBJECTS_SELFTEST
 325         bool "Debug objects selftest"
 326         depends on DEBUG_OBJECTS
 327         help
 328           This enables the selftest of the object debug code.
 329
 330 config DEBUG_OBJECTS_FREE
 331         bool "Debug objects in freed memory"
 332         depends on DEBUG_OBJECTS
 333         help
 334           This enables checks whether a k/v free operation frees an area
 335           which contains an object which has not been deactivated
 336           properly. This can make kmalloc/kfree-intensive workloads
 337           much slower.
 338
 339 config DEBUG_OBJECTS_TIMERS
 340         bool "Debug timer objects"
 341         depends on DEBUG_OBJECTS
 342         help
 343           If you say Y here, additional code will be inserted into the
 344           timer routines to track the life time of timer objects and
 345           validate the timer operations.
 346
 347 config DEBUG_OBJECTS_WORK
 348         bool "Debug work objects"
 349         depends on DEBUG_OBJECTS
 350         help
 351           If you say Y here, additional code will be inserted into the
 352           work queue routines to track the life time of work objects and
 353           validate the work operations.
 354
 355 config DEBUG_OBJECTS_RCU_HEAD
 356         bool "Debug RCU callbacks objects"
 357         depends on DEBUG_OBJECTS
 358         help
 359           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 360
 361 config DEBUG_OBJECTS_PERCPU_COUNTER
 362         bool "Debug percpu counter objects"
 363         depends on DEBUG_OBJECTS
 364         help
 365           If you say Y here, additional code will be inserted into the
 366           percpu counter routines to track the life time of percpu counter
 367           objects and validate the percpu counter operations.
 368
 369 config DEBUG_OBJECTS_ENABLE_DEFAULT
 370         int "debug_objects bootup default value (0-1)"
 371         range 0 1
 372         default "1"
 373         depends on DEBUG_OBJECTS
 374         help
 375           Debug objects boot parameter default value
 376
 377 config DEBUG_SLAB
 378         bool "Debug slab memory allocations"
 379         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 380         help
 381           Say Y here to have the kernel do limited verification on memory
 382           allocation as well as poisoning memory on free to catch use of freed
 383           memory. This can make kmalloc/kfree-intensive workloads much slower.
 384
 385 config DEBUG_SLAB_LEAK
 386         bool "Memory leak debugging"
 387         depends on DEBUG_SLAB
 388
 389 config SLUB_DEBUG_ON
 390         bool "SLUB debugging on by default"
 391         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 392         default n
 393         help
 394           Boot with debugging on by default. SLUB boots by default with
 395           the runtime debug capabilities switched off. Enabling this is
 396           equivalent to specifying the "slub_debug" parameter on boot.
 397           There is no support for more fine grained debug control like
 398           possible with slub_debug=xxx. SLUB debugging may be switched
 399           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 400           "slub_debug=-".
 401
 402 config SLUB_STATS
 403         default n
 404         bool "Enable SLUB performance statistics"
 405         depends on SLUB && SYSFS
 406         help
 407           SLUB statistics are useful to debug SLUBs allocation behavior in
 408           order find ways to optimize the allocator. This should never be
 409           enabled for production use since keeping statistics slows down
 410           the allocator by a few percentage points. The slabinfo command
 411           supports the determination of the most active slabs to figure
 412           out which slabs are relevant to a particular load.
 413           Try running: slabinfo -DA
 414
 415 config DEBUG_KMEMLEAK
 416         bool "Kernel memory leak detector"
 417         depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
 418                 (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
 419
 420         select DEBUG_FS
 421         select STACKTRACE if STACKTRACE_SUPPORT
 422         select KALLSYMS
 423         select CRC32
 424         help
 425           Say Y here if you want to enable the memory leak
 426           detector. The memory allocation/freeing is traced in a way
 427           similar to the Boehm's conservative garbage collector, the
 428           difference being that the orphan objects are not freed but
 429           only shown in /sys/kernel/debug/kmemleak. Enabling this
 430           feature will introduce an overhead to memory
 431           allocations. See Documentation/kmemleak.txt for more
 432           details.
 433
 434           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 435           of finding leaks due to the slab objects poisoning.
 436
 437           In order to access the kmemleak file, debugfs needs to be
 438           mounted (usually at /sys/kernel/debug).
 439
 440 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 441         int "Maximum kmemleak early log entries"
 442         depends on DEBUG_KMEMLEAK
 443         range 200 40000
 444         default 400
 445         help
 446           Kmemleak must track all the memory allocations to avoid
 447           reporting false positives. Since memory may be allocated or
 448           freed before kmemleak is initialised, an early log buffer is
 449           used to store these actions. If kmemleak reports "early log
 450           buffer exceeded", please increase this value.
 451
 452 config DEBUG_KMEMLEAK_TEST
 453         tristate "Simple test for the kernel memory leak detector"
 454         depends on DEBUG_KMEMLEAK && m
 455         help
 456           This option enables a module that explicitly leaks memory.
 457
 458           If unsure, say N.
 459
 460 config DEBUG_KMEMLEAK_DEFAULT_OFF
 461         bool "Default kmemleak to off"
 462         depends on DEBUG_KMEMLEAK
 463         help
 464           Say Y here to disable kmemleak by default. It can then be enabled
 465           on the command line via kmemleak=on.
 466
 467 config DEBUG_PREEMPT
 468         bool "Debug preemptible kernel"
 469         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 470         default y
 471         help
 472           If you say Y here then the kernel will use a debug variant of the
 473           commonly used smp_processor_id() function and will print warnings
 474           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 475           will detect preemption count underflows.
 476
 477 config DEBUG_RT_MUTEXES
 478         bool "RT Mutex debugging, deadlock detection"
 479         depends on DEBUG_KERNEL && RT_MUTEXES
 480         help
 481          This allows rt mutex semantics violations and rt mutex related
 482          deadlocks (lockups) to be detected and reported automatically.
 483
 484 config DEBUG_PI_LIST
 485         bool
 486         default y
 487         depends on DEBUG_RT_MUTEXES
 488
 489 config RT_MUTEX_TESTER
 490         bool "Built-in scriptable tester for rt-mutexes"
 491         depends on DEBUG_KERNEL && RT_MUTEXES
 492         help
 493           This option enables a rt-mutex tester.
 494
 495 config DEBUG_SPINLOCK
 496         bool "Spinlock and rw-lock debugging: basic checks"
 497         depends on DEBUG_KERNEL
 498         help
 499           Say Y here and build SMP to catch missing spinlock initialization
 500           and certain other kinds of spinlock errors commonly made.  This is
 501           best used in conjunction with the NMI watchdog so that spinlock
 502           deadlocks are also debuggable.
 503
 504 config DEBUG_MUTEXES
 505         bool "Mutex debugging: basic checks"
 506         depends on DEBUG_KERNEL
 507         help
 508          This feature allows mutex semantics violations to be detected and
 509          reported.
 510
 511 config DEBUG_LOCK_ALLOC
 512         bool "Lock debugging: detect incorrect freeing of live locks"
 513         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 514         select DEBUG_SPINLOCK
 515         select DEBUG_MUTEXES
 516         select LOCKDEP
 517         help
 518          This feature will check whether any held lock (spinlock, rwlock,
 519          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 520          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 521          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 522          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 523          held during task exit.
 524
 525 config PROVE_LOCKING
 526         bool "Lock debugging: prove locking correctness"
 527         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 528         select LOCKDEP
 529         select DEBUG_SPINLOCK
 530         select DEBUG_MUTEXES
 531         select DEBUG_LOCK_ALLOC
 532         select TRACE_IRQFLAGS
 533         default n
 534         help
 535          This feature enables the kernel to prove that all locking
 536          that occurs in the kernel runtime is mathematically
 537          correct: that under no circumstance could an arbitrary (and
 538          not yet triggered) combination of observed locking
 539          sequences (on an arbitrary number of CPUs, running an
 540          arbitrary number of tasks and interrupt contexts) cause a
 541          deadlock.
 542
 543          In short, this feature enables the kernel to report locking
 544          related deadlocks before they actually occur.
 545
 546          The proof does not depend on how hard and complex a
 547          deadlock scenario would be to trigger: how many
 548          participant CPUs, tasks and irq-contexts would be needed
 549          for it to trigger. The proof also does not depend on
 550          timing: if a race and a resulting deadlock is possible
 551          theoretically (no matter how unlikely the race scenario
 552          is), it will be proven so and will immediately be
 553          reported by the kernel (once the event is observed that
 554          makes the deadlock theoretically possible).
 555
 556          If a deadlock is impossible (i.e. the locking rules, as
 557          observed by the kernel, are mathematically correct), the
 558          kernel reports nothing.
 559
 560          NOTE: this feature can also be enabled for rwlocks, mutexes
 561          and rwsems - in which case all dependencies between these
 562          different locking variants are observed and mapped too, and
 563          the proof of observed correctness is also maintained for an
 564          arbitrary combination of these separate locking variants.
 565
 566          For more details, see Documentation/lockdep-design.txt.
 567
 568 config PROVE_RCU
 569         bool "RCU debugging: prove RCU correctness"
 570         depends on PROVE_LOCKING
 571         default n
 572         help
 573          This feature enables lockdep extensions that check for correct
 574          use of RCU APIs.  This is currently under development.  Say Y
 575          if you want to debug RCU usage or help work on the PROVE_RCU
 576          feature.
 577
 578          Say N if you are unsure.
 579
 580 config PROVE_RCU_REPEATEDLY
 581         bool "RCU debugging: don't disable PROVE_RCU on first splat"
 582         depends on PROVE_RCU
 583         default n
 584         help
 585          By itself, PROVE_RCU will disable checking upon issuing the
 586          first warning (or "splat").  This feature prevents such
 587          disabling, allowing multiple RCU-lockdep warnings to be printed
 588          on a single reboot.
 589
 590          Say Y to allow multiple RCU-lockdep warnings per boot.
 591
 592          Say N if you are unsure.
 593
 594 config SPARSE_RCU_POINTER
 595         bool "RCU debugging: sparse-based checks for pointer usage"
 596         default n
 597         help
 598          This feature enables the __rcu sparse annotation for
 599          RCU-protected pointers.  This annotation will cause sparse
 600          to flag any non-RCU used of annotated pointers.  This can be
 601          helpful when debugging RCU usage.  Please note that this feature
 602          is not intended to enforce code cleanliness; it is instead merely
 603          a debugging aid.
 604
 605          Say Y to make sparse flag questionable use of RCU-protected pointers
 606
 607          Say N if you are unsure.
 608
 609 config LOCKDEP
 610         bool
 611         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 612         select STACKTRACE
 613         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 614         select KALLSYMS
 615         select KALLSYMS_ALL
 616
 617 config LOCK_STAT
 618         bool "Lock usage statistics"
 619         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 620         select LOCKDEP
 621         select DEBUG_SPINLOCK
 622         select DEBUG_MUTEXES
 623         select DEBUG_LOCK_ALLOC
 624         default n
 625         help
 626          This feature enables tracking lock contention points
 627
 628          For more details, see Documentation/lockstat.txt
 629
 630          This also enables lock events required by "perf lock",
 631          subcommand of perf.
 632          If you want to use "perf lock", you also need to turn on
 633          CONFIG_EVENT_TRACING.
 634
 635          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 636          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 637
 638 config DEBUG_LOCKDEP
 639         bool "Lock dependency engine debugging"
 640         depends on DEBUG_KERNEL && LOCKDEP
 641         help
 642           If you say Y here, the lock dependency engine will do
 643           additional runtime checks to debug itself, at the price
 644           of more runtime overhead.
 645
 646 config TRACE_IRQFLAGS
 647         bool
 648         help
 649           Enables hooks to interrupt enabling and disabling for
 650           either tracing or lock debugging.
 651
 652 config DEBUG_ATOMIC_SLEEP
 653         bool "Sleep inside atomic section checking"
 654         select PREEMPT_COUNT
 655         depends on DEBUG_KERNEL
 656         help
 657           If you say Y here, various routines which may sleep will become very
 658           noisy if they are called inside atomic sections: when a spinlock is
 659           held, inside an rcu read side critical section, inside preempt disabled
 660           sections, inside an interrupt, etc...
 661
 662 config DEBUG_LOCKING_API_SELFTESTS
 663         bool "Locking API boot-time self-tests"
 664         depends on DEBUG_KERNEL
 665         help
 666           Say Y here if you want the kernel to run a short self-test during
 667           bootup. The self-test checks whether common types of locking bugs
 668           are detected by debugging mechanisms or not. (if you disable
 669           lock debugging then those bugs wont be detected of course.)
 670           The following locking APIs are covered: spinlocks, rwlocks,
 671           mutexes and rwsems.
 672
 673 config STACKTRACE
 674         bool
 675         depends on STACKTRACE_SUPPORT
 676
 677 config DEBUG_STACK_USAGE
 678         bool "Stack utilization instrumentation"
 679         depends on DEBUG_KERNEL
 680         help
 681           Enables the display of the minimum amount of free stack which each
 682           task has ever had available in the sysrq-T and sysrq-P debug output.
 683
 684           This option will slow down process creation somewhat.
 685
 686 config DEBUG_KOBJECT
 687         bool "kobject debugging"
 688         depends on DEBUG_KERNEL
 689         help
 690           If you say Y here, some extra kobject debugging messages will be sent
 691           to the syslog.
 692
 693 config DEBUG_HIGHMEM
 694         bool "Highmem debugging"
 695         depends on DEBUG_KERNEL && HIGHMEM
 696         help
 697           This options enables addition error checking for high memory systems.
 698           Disable for production systems.
 699
 700 config DEBUG_BUGVERBOSE
 701         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
 702         depends on BUG
 703         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 704                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || TILE
 705         default y
 706         help
 707           Say Y here to make BUG() panics output the file name and line number
 708           of the BUG call as well as the EIP and oops trace.  This aids
 709           debugging but costs about 70-100K of memory.
 710
 711 config DEBUG_INFO
 712         bool "Compile the kernel with debug info"
 713         depends on DEBUG_KERNEL
 714         help
 715           If you say Y here the resulting kernel image will include
 716           debugging info resulting in a larger kernel image.
 717           This adds debug symbols to the kernel and modules (gcc -g), and
 718           is needed if you intend to use kernel crashdump or binary object
 719           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 720           Say Y here only if you plan to debug the kernel.
 721
 722           If unsure, say N.
 723
 724 config DEBUG_INFO_REDUCED
 725         bool "Reduce debugging information"
 726         depends on DEBUG_INFO
 727         help
 728           If you say Y here gcc is instructed to generate less debugging
 729           information for structure types. This means that tools that
 730           need full debugging information (like kgdb or systemtap) won't
 731           be happy. But if you merely need debugging information to
 732           resolve line numbers there is no loss. Advantage is that
 733           build directory object sizes shrink dramatically over a full
 734           DEBUG_INFO build and compile times are reduced too.
 735           Only works with newer gcc versions.
 736
 737 config DEBUG_VM
 738         bool "Debug VM"
 739         depends on DEBUG_KERNEL
 740         help
 741           Enable this to turn on extended checks in the virtual-memory system
 742           that may impact performance.
 743
 744           If unsure, say N.
 745
 746 config DEBUG_VIRTUAL
 747         bool "Debug VM translations"
 748         depends on DEBUG_KERNEL && X86
 749         help
 750           Enable some costly sanity checks in virtual to page code. This can
 751           catch mistakes with virt_to_page() and friends.
 752
 753           If unsure, say N.
 754
 755 config DEBUG_NOMMU_REGIONS
 756         bool "Debug the global anon/private NOMMU mapping region tree"
 757         depends on DEBUG_KERNEL && !MMU
 758         help
 759           This option causes the global tree of anonymous and private mapping
 760           regions to be regularly checked for invalid topology.
 761
 762 config DEBUG_WRITECOUNT
 763         bool "Debug filesystem writers count"
 764         depends on DEBUG_KERNEL
 765         help
 766           Enable this to catch wrong use of the writers count in struct
 767           vfsmount.  This will increase the size of each file struct by
 768           32 bits.
 769
 770           If unsure, say N.
 771
 772 config DEBUG_MEMORY_INIT
 773         bool "Debug memory initialisation" if EXPERT
 774         default !EXPERT
 775         help
 776           Enable this for additional checks during memory initialisation.
 777           The sanity checks verify aspects of the VM such as the memory model
 778           and other information provided by the architecture. Verbose
 779           information will be printed at KERN_DEBUG loglevel depending
 780           on the mminit_loglevel= command-line option.
 781
 782           If unsure, say Y
 783
 784 config DEBUG_LIST
 785         bool "Debug linked list manipulation"
 786         depends on DEBUG_KERNEL
 787         help
 788           Enable this to turn on extended checks in the linked-list
 789           walking routines.
 790
 791           If unsure, say N.
 792
 793 config TEST_LIST_SORT
 794         bool "Linked list sorting test"
 795         depends on DEBUG_KERNEL
 796         help
 797           Enable this to turn on 'list_sort()' function test. This test is
 798           executed only once during system boot, so affects only boot time.
 799
 800           If unsure, say N.
 801
 802 config DEBUG_SG
 803         bool "Debug SG table operations"
 804         depends on DEBUG_KERNEL
 805         help
 806           Enable this to turn on checks on scatter-gather tables. This can
 807           help find problems with drivers that do not properly initialize
 808           their sg tables.
 809
 810           If unsure, say N.
 811
 812 config DEBUG_NOTIFIERS
 813         bool "Debug notifier call chains"
 814         depends on DEBUG_KERNEL
 815         help
 816           Enable this to turn on sanity checking for notifier call chains.
 817           This is most useful for kernel developers to make sure that
 818           modules properly unregister themselves from notifier chains.
 819           This is a relatively cheap check but if you care about maximum
 820           performance, say N.
 821
 822 config DEBUG_CREDENTIALS
 823         bool "Debug credential management"
 824         depends on DEBUG_KERNEL
 825         help
 826           Enable this to turn on some debug checking for credential
 827           management.  The additional code keeps track of the number of
 828           pointers from task_structs to any given cred struct, and checks to
 829           see that this number never exceeds the usage count of the cred
 830           struct.
 831
 832           Furthermore, if SELinux is enabled, this also checks that the
 833           security pointer in the cred struct is never seen to be invalid.
 834
 835           If unsure, say N.
 836
 837 #
 838 # Select this config option from the architecture Kconfig, if it
 839 # is preferred to always offer frame pointers as a config
 840 # option on the architecture (regardless of KERNEL_DEBUG):
 841 #
 842 config ARCH_WANT_FRAME_POINTERS
 843         bool
 844         help
 845
 846 config FRAME_POINTER
 847         bool "Compile the kernel with frame pointers"
 848         depends on DEBUG_KERNEL && \
 849                 (CRIS || M68K || FRV || UML || \
 850                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 851                 ARCH_WANT_FRAME_POINTERS
 852         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 853         help
 854           If you say Y here the resulting kernel image will be slightly
 855           larger and slower, but it gives very useful debugging information
 856           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 857
 858 config BOOT_PRINTK_DELAY
 859         bool "Delay each boot printk message by N milliseconds"
 860         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 861         help
 862           This build option allows you to read kernel boot messages
 863           by inserting a short delay after each one.  The delay is
 864           specified in milliseconds on the kernel command line,
 865           using "boot_delay=N".
 866
 867           It is likely that you would also need to use "lpj=M" to preset
 868           the "loops per jiffie" value.
 869           See a previous boot log for the "lpj" value to use for your
 870           system, and then set "lpj=M" before setting "boot_delay=N".
 871           NOTE:  Using this option may adversely affect SMP systems.
 872           I.e., processors other than the first one may not boot up.
 873           BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
 874           what it believes to be lockup conditions.
 875
 876 config RCU_TORTURE_TEST
 877         tristate "torture tests for RCU"
 878         depends on DEBUG_KERNEL
 879         default n
 880         help
 881           This option provides a kernel module that runs torture tests
 882           on the RCU infrastructure.  The kernel module may be built
 883           after the fact on the running kernel to be tested, if desired.
 884
 885           Say Y here if you want RCU torture tests to be built into
 886           the kernel.
 887           Say M if you want the RCU torture tests to build as a module.
 888           Say N if you are unsure.
 889
 890 config RCU_TORTURE_TEST_RUNNABLE
 891         bool "torture tests for RCU runnable by default"
 892         depends on RCU_TORTURE_TEST = y
 893         default n
 894         help
 895           This option provides a way to build the RCU torture tests
 896           directly into the kernel without them starting up at boot
 897           time.  You can use /proc/sys/kernel/rcutorture_runnable
 898           to manually override this setting.  This /proc file is
 899           available only when the RCU torture tests have been built
 900           into the kernel.
 901
 902           Say Y here if you want the RCU torture tests to start during
 903           boot (you probably don't).
 904           Say N here if you want the RCU torture tests to start only
 905           after being manually enabled via /proc.
 906
 907 config RCU_CPU_STALL_TIMEOUT
 908         int "RCU CPU stall timeout in seconds"
 909         depends on TREE_RCU || TREE_PREEMPT_RCU
 910         range 3 300
 911         default 60
 912         help
 913           If a given RCU grace period extends more than the specified
 914           number of seconds, a CPU stall warning is printed.  If the
 915           RCU grace period persists, additional CPU stall warnings are
 916           printed at more widely spaced intervals.
 917
 918 config RCU_CPU_STALL_VERBOSE
 919         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 920         depends on TREE_PREEMPT_RCU
 921         default y
 922         help
 923           This option causes RCU to printk detailed per-task information
 924           for any tasks that are stalling the current RCU grace period.
 925
 926           Say N if you are unsure.
 927
 928           Say Y if you want to enable such checks.
 929
 930 config KPROBES_SANITY_TEST
 931         bool "Kprobes sanity tests"
 932         depends on DEBUG_KERNEL
 933         depends on KPROBES
 934         default n
 935         help
 936           This option provides for testing basic kprobes functionality on
 937           boot. A sample kprobe, jprobe and kretprobe are inserted and
 938           verified for functionality.
 939
 940           Say N if you are unsure.
 941
 942 config BACKTRACE_SELF_TEST
 943         tristate "Self test for the backtrace code"
 944         depends on DEBUG_KERNEL
 945         default n
 946         help
 947           This option provides a kernel module that can be used to test
 948           the kernel stack backtrace code. This option is not useful
 949           for distributions or general kernels, but only for kernel
 950           developers working on architecture code.
 951
 952           Note that if you want to also test saved backtraces, you will
 953           have to enable STACKTRACE as well.
 954
 955           Say N if you are unsure.
 956
 957 config DEBUG_BLOCK_EXT_DEVT
 958         bool "Force extended block device numbers and spread them"
 959         depends on DEBUG_KERNEL
 960         depends on BLOCK
 961         default n
 962         help
 963           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 964           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 965           YOU ARE DOING.  Distros, please enable this and fix whatever
 966           is broken.
 967
 968           Conventionally, block device numbers are allocated from
 969           predetermined contiguous area.  However, extended block area
 970           may introduce non-contiguous block device numbers.  This
 971           option forces most block device numbers to be allocated from
 972           the extended space and spreads them to discover kernel or
 973           userland code paths which assume predetermined contiguous
 974           device number allocation.
 975
 976           Note that turning on this debug option shuffles all the
 977           device numbers for all IDE and SCSI devices including libata
 978           ones, so root partition specified using device number
 979           directly (via rdev or root=MAJ:MIN) won't work anymore.
 980           Textual device names (root=/dev/sdXn) will continue to work.
 981
 982           Say N if you are unsure.
 983
 984 config DEBUG_FORCE_WEAK_PER_CPU
 985         bool "Force weak per-cpu definitions"
 986         depends on DEBUG_KERNEL
 987         help
 988           s390 and alpha require percpu variables in modules to be
 989           defined weak to work around addressing range issue which
 990           puts the following two restrictions on percpu variable
 991           definitions.
 992
 993           1. percpu symbols must be unique whether static or not
 994           2. percpu variables can't be defined inside a function
 995
 996           To ensure that generic code follows the above rules, this
 997           option forces all percpu variables to be defined as weak.
 998
 999 config DEBUG_PER_CPU_MAPS
1000         bool "Debug access to per_cpu maps"
1001         depends on DEBUG_KERNEL
1002         depends on SMP
1003         help
1004           Say Y to verify that the per_cpu map being accessed has
1005           been set up. This adds a fair amount of code to kernel memory
1006           and decreases performance.
1007
1008           Say N if unsure.
1009
1010 config LKDTM
1011         tristate "Linux Kernel Dump Test Tool Module"
1012         depends on DEBUG_FS
1013         depends on BLOCK
1014         default n
1015         help
1016         This module enables testing of the different dumping mechanisms by
1017         inducing system failures at predefined crash points.
1018         If you don't need it: say N
1019         Choose M here to compile this code as a module. The module will be
1020         called lkdtm.
1021
1022         Documentation on how to use the module can be found in
1023         Documentation/fault-injection/provoke-crashes.txt
1024
1025 config CPU_NOTIFIER_ERROR_INJECT
1026         tristate "CPU notifier error injection module"
1027         depends on HOTPLUG_CPU && DEBUG_KERNEL
1028         help
1029           This option provides a kernel module that can be used to test
1030           the error handling of the cpu notifiers
1031
1032           To compile this code as a module, choose M here: the module will
1033           be called cpu-notifier-error-inject.
1034
1035           If unsure, say N.
1036
1037 config FAULT_INJECTION
1038         bool "Fault-injection framework"
1039         depends on DEBUG_KERNEL
1040         help
1041           Provide fault-injection framework.
1042           For more details, see Documentation/fault-injection/.
1043
1044 config FAILSLAB
1045         bool "Fault-injection capability for kmalloc"
1046         depends on FAULT_INJECTION
1047         depends on SLAB || SLUB
1048         help
1049           Provide fault-injection capability for kmalloc.
1050
1051 config FAIL_PAGE_ALLOC
1052         bool "Fault-injection capabilitiy for alloc_pages()"
1053         depends on FAULT_INJECTION
1054         help
1055           Provide fault-injection capability for alloc_pages().
1056
1057 config FAIL_MAKE_REQUEST
1058         bool "Fault-injection capability for disk IO"
1059         depends on FAULT_INJECTION && BLOCK
1060         help
1061           Provide fault-injection capability for disk IO.
1062
1063 config FAIL_IO_TIMEOUT
1064         bool "Fault-injection capability for faking disk interrupts"
1065         depends on FAULT_INJECTION && BLOCK
1066         help
1067           Provide fault-injection capability on end IO handling. This
1068           will make the block layer "forget" an interrupt as configured,
1069           thus exercising the error handling.
1070
1071           Only works with drivers that use the generic timeout handling,
1072           for others it wont do anything.
1073
1074 config FAIL_MMC_REQUEST
1075         bool "Fault-injection capability for MMC IO"
1076         select DEBUG_FS
1077         depends on FAULT_INJECTION && MMC
1078         help
1079           Provide fault-injection capability for MMC IO.
1080           This will make the mmc core return data errors. This is
1081           useful to test the error handling in the mmc block device
1082           and to test how the mmc host driver handles retries from
1083           the block device.
1084
1085 config FAULT_INJECTION_DEBUG_FS
1086         bool "Debugfs entries for fault-injection capabilities"
1087         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1088         help
1089           Enable configuration of fault-injection capabilities via debugfs.
1090
1091 config FAULT_INJECTION_STACKTRACE_FILTER
1092         bool "stacktrace filter for fault-injection capabilities"
1093         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1094         depends on !X86_64
1095         select STACKTRACE
1096         select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1097         help
1098           Provide stacktrace filter for fault-injection capabilities
1099
1100 config LATENCYTOP
1101         bool "Latency measuring infrastructure"
1102         depends on HAVE_LATENCYTOP_SUPPORT
1103         depends on DEBUG_KERNEL
1104         depends on STACKTRACE_SUPPORT
1105         depends on PROC_FS
1106         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1107         select KALLSYMS
1108         select KALLSYMS_ALL
1109         select STACKTRACE
1110         select SCHEDSTATS
1111         select SCHED_DEBUG
1112         help
1113           Enable this option if you want to use the LatencyTOP tool
1114           to find out which userspace is blocking on what kernel operations.
1115
1116 config SYSCTL_SYSCALL_CHECK
1117         bool "Sysctl checks"
1118         depends on SYSCTL
1119         ---help---
1120           sys_sysctl uses binary paths that have been found challenging
1121           to properly maintain and use. This enables checks that help
1122           you to keep things correct.
1123
1124 source mm/Kconfig.debug
1125 source kernel/trace/Kconfig
1126
1127 config PROVIDE_OHCI1394_DMA_INIT
1128         bool "Remote debugging over FireWire early on boot"
1129         depends on PCI && X86
1130         help
1131           If you want to debug problems which hang or crash the kernel early
1132           on boot and the crashing machine has a FireWire port, you can use
1133           this feature to remotely access the memory of the crashed machine
1134           over FireWire. This employs remote DMA as part of the OHCI1394
1135           specification which is now the standard for FireWire controllers.
1136
1137           With remote DMA, you can monitor the printk buffer remotely using
1138           firescope and access all memory below 4GB using fireproxy from gdb.
1139           Even controlling a kernel debugger is possible using remote DMA.
1140
1141           Usage:
1142
1143           If ohci1394_dma=early is used as boot parameter, it will initialize
1144           all OHCI1394 controllers which are found in the PCI config space.
1145
1146           As all changes to the FireWire bus such as enabling and disabling
1147           devices cause a bus reset and thereby disable remote DMA for all
1148           devices, be sure to have the cable plugged and FireWire enabled on
1149           the debugging host before booting the debug target for debugging.
1150
1151           This code (~1k) is freed after boot. By then, the firewire stack
1152           in charge of the OHCI-1394 controllers should be used instead.
1153
1154           See Documentation/debugging-via-ohci1394.txt for more information.
1155
1156 config FIREWIRE_OHCI_REMOTE_DMA
1157         bool "Remote debugging over FireWire with firewire-ohci"
1158         depends on FIREWIRE_OHCI
1159         help
1160           This option lets you use the FireWire bus for remote debugging
1161           with help of the firewire-ohci driver. It enables unfiltered
1162           remote DMA in firewire-ohci.
1163           See Documentation/debugging-via-ohci1394.txt for more information.
1164
1165           If unsure, say N.
1166
1167 config BUILD_DOCSRC
1168         bool "Build targets in Documentation/ tree"
1169         depends on HEADERS_CHECK
1170         help
1171           This option attempts to build objects from the source files in the
1172           kernel Documentation/ tree.
1173
1174           Say N if you are unsure.
1175
1176 config DYNAMIC_DEBUG
1177         bool "Enable dynamic printk() support"
1178         default n
1179         depends on PRINTK
1180         depends on DEBUG_FS
1181         help
1182
1183           Compiles debug level messages into the kernel, which would not
1184           otherwise be available at runtime. These messages can then be
1185           enabled/disabled based on various levels of scope - per source file,
1186           function, module, format string, and line number. This mechanism
1187           implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1188           this compile option is a larger kernel text size of about 2%.
1189
1190           Usage:
1191
1192           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1193           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1194           filesystem must first be mounted before making use of this feature.
1195           We refer the control file as: <debugfs>/dynamic_debug/control. This
1196           file contains a list of the debug statements that can be enabled. The
1197           format for each line of the file is:
1198
1199                 filename:lineno [module]function flags format
1200
1201           filename : source file of the debug statement
1202           lineno : line number of the debug statement
1203           module : module that contains the debug statement
1204           function : function that contains the debug statement
1205           flags : 'p' means the line is turned 'on' for printing
1206           format : the format used for the debug statement
1207
1208           From a live system:
1209
1210                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1211                 # filename:lineno [module]function flags format
1212                 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1213                 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1214                 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1215
1216           Example usage:
1217
1218                 // enable the message at line 1603 of file svcsock.c
1219                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1220                                                 <debugfs>/dynamic_debug/control
1221
1222                 // enable all the messages in file svcsock.c
1223                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1224                                                 <debugfs>/dynamic_debug/control
1225
1226                 // enable all the messages in the NFS server module
1227                 nullarbor:~ # echo -n 'module nfsd +p' >
1228                                                 <debugfs>/dynamic_debug/control
1229
1230                 // enable all 12 messages in the function svc_process()
1231                 nullarbor:~ # echo -n 'func svc_process +p' >
1232                                                 <debugfs>/dynamic_debug/control
1233
1234                 // disable all 12 messages in the function svc_process()
1235                 nullarbor:~ # echo -n 'func svc_process -p' >
1236                                                 <debugfs>/dynamic_debug/control
1237
1238           See Documentation/dynamic-debug-howto.txt for additional information.
1239
1240 config DMA_API_DEBUG
1241         bool "Enable debugging of DMA-API usage"
1242         depends on HAVE_DMA_API_DEBUG
1243         help
1244           Enable this option to debug the use of the DMA API by device drivers.
1245           With this option you will be able to detect common bugs in device
1246           drivers like double-freeing of DMA mappings or freeing mappings that
1247           were never allocated.
1248           This option causes a performance degredation.  Use only if you want
1249           to debug device drivers. If unsure, say N.
1250
1251 config ATOMIC64_SELFTEST
1252         bool "Perform an atomic64_t self-test at boot"
1253         help
1254           Enable this option to test the atomic64_t functions at boot.
1255
1256           If unsure, say N.
1257
1258 config ASYNC_RAID6_TEST
1259         tristate "Self test for hardware accelerated raid6 recovery"
1260         depends on ASYNC_RAID6_RECOV
1261         select ASYNC_MEMCPY
1262         ---help---
1263           This is a one-shot self test that permutes through the
1264           recovery of all the possible two disk failure scenarios for a
1265           N-disk array.  Recovery is performed with the asynchronous
1266           raid6 recovery routines, and will optionally use an offload
1267           engine if one is available.
1268
1269           If unsure, say N.
1270
1271 source "samples/Kconfig"
1272
1273 source "lib/Kconfig.kgdb"
1274
1275 source "lib/Kconfig.kmemcheck"
1276
1277 config TEST_KSTRTOX
1278         tristate "Test kstrto*() family of functions at runtime"