lib/Kconfig.debug

   1
   2 config PRINTK_TIME
   3         bool "Show timing information on printks"
   4         depends on PRINTK
   5         help
   6           Selecting this option causes timing information to be
   7           included in printk output.  This allows you to measure
   8           the interval between kernel operations, including bootup
   9           operations.  This is useful for identifying long delays
  10           in kernel startup.
  11
  12 config ENABLE_WARN_DEPRECATED
  13         bool "Enable __deprecated logic"
  14         default y
  15         help
  16           Enable the __deprecated logic in the kernel build.
  17           Disable this to suppress the "warning: 'foo' is deprecated
  18           (declared at kernel/power/somefile.c:1234)" messages.
  19
  20 config ENABLE_MUST_CHECK
  21         bool "Enable __must_check logic"
  22         default y
  23         help
  24           Enable the __must_check logic in the kernel build.  Disable this to
  25           suppress the "warning: ignoring return value of 'foo', declared with
  26           attribute warn_unused_result" messages.
  27
  28 config FRAME_WARN
  29         int "Warn for stack frames larger than (needs gcc 4.4)"
  30         range 0 8192
  31         default 1024 if !64BIT
  32         default 2048 if 64BIT
  33         help
  34           Tell gcc to warn at build time for stack frames larger than this.
  35           Setting this too low will cause a lot of warnings.
  36           Setting it to 0 disables the warning.
  37           Requires gcc 4.4
  38
  39 config MAGIC_SYSRQ
  40         bool "Magic SysRq key"
  41         depends on !UML
  42         help
  43           If you say Y here, you will have some control over the system even
  44           if the system crashes for example during kernel debugging (e.g., you
  45           will be able to flush the buffer cache to disk, reboot the system
  46           immediately or dump some status information). This is accomplished
  47           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  48           also works on a serial console (on PC hardware at least), if you
  49           send a BREAK and then within 5 seconds a command keypress. The
  50           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  51           unless you really know what this hack does.
  52
  53 config STRIP_ASM_SYMS
  54         bool "Strip assembler-generated symbols during link"
  55         default n
  56         help
  57           Strip internal assembler-generated symbols during a link (symbols
  58           that look like '.Lxxx') so they don't pollute the output of
  59           get_wchan() and suchlike.
  60
  61 config UNUSED_SYMBOLS
  62         bool "Enable unused/obsolete exported symbols"
  63         default y if X86
  64         help
  65           Unused but exported symbols make the kernel needlessly bigger.  For
  66           that reason most of these unused exports will soon be removed.  This
  67           option is provided temporarily to provide a transition period in case
  68           some external kernel module needs one of these symbols anyway. If you
  69           encounter such a case in your module, consider if you are actually
  70           using the right API.  (rationale: since nobody in the kernel is using
  71           this in a module, there is a pretty good chance it's actually the
  72           wrong interface to use).  If you really need the symbol, please send a
  73           mail to the linux kernel mailing list mentioning the symbol and why
  74           you really need it, and what the merge plan to the mainline kernel for
  75           your module is.
  76
  77 config DEBUG_FS
  78         bool "Debug Filesystem"
  79         help
  80           debugfs is a virtual file system that kernel developers use to put
  81           debugging files into.  Enable this option to be able to read and
  82           write to these files.
  83
  84           For detailed documentation on the debugfs API, see
  85           Documentation/DocBook/filesystems.
  86
  87           If unsure, say N.
  88
  89 config HEADERS_CHECK
  90         bool "Run 'make headers_check' when building vmlinux"
  91         depends on !UML
  92         help
  93           This option will extract the user-visible kernel headers whenever
  94           building the kernel, and will run basic sanity checks on them to
  95           ensure that exported files do not attempt to include files which
  96           were not exported, etc.
  97
  98           If you're making modifications to header files which are
  99           relevant for userspace, say 'Y', and check the headers
 100           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 101           your build tree), to make sure they're suitable.
 102
 103 config DEBUG_SECTION_MISMATCH
 104         bool "Enable full Section mismatch analysis"
 105         depends on UNDEFINED || (BLACKFIN)
 106         default y
 107         # This option is on purpose disabled for now.
 108         # It will be enabled when we are down to a reasonable number
 109         # of section mismatch warnings (< 10 for an allyesconfig build)
 110         help
 111           The section mismatch analysis checks if there are illegal
 112           references from one section to another section.
 113           Linux will during link or during runtime drop some sections
 114           and any use of code/data previously in these sections will
 115           most likely result in an oops.
 116           In the code functions and variables are annotated with
 117           __init, __devinit etc. (see full list in include/linux/init.h)
 118           which results in the code/data being placed in specific sections.
 119           The section mismatch analysis is always done after a full
 120           kernel build but enabling this option will in addition
 121           do the following:
 122           - Add the option -fno-inline-functions-called-once to gcc
 123             When inlining a function annotated __init in a non-init
 124             function we would lose the section information and thus
 125             the analysis would not catch the illegal reference.
 126             This option tells gcc to inline less but will also
 127             result in a larger kernel.
 128           - Run the section mismatch analysis for each module/built-in.o
 129             When we run the section mismatch analysis on vmlinux.o we
 130             lose valueble information about where the mismatch was
 131             introduced.
 132             Running the analysis for each module/built-in.o file
 133             will tell where the mismatch happens much closer to the
 134             source. The drawback is that we will report the same
 135             mismatch at least twice.
 136           - Enable verbose reporting from modpost to help solving
 137             the section mismatches reported.
 138
 139 config DEBUG_KERNEL
 140         bool "Kernel debugging"
 141         help
 142           Say Y here if you are developing drivers or trying to debug and
 143           identify kernel problems.
 144
 145 config DEBUG_SHIRQ
 146         bool "Debug shared IRQ handlers"
 147         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 148         help
 149           Enable this to generate a spurious interrupt as soon as a shared
 150           interrupt handler is registered, and just before one is deregistered.
 151           Drivers ought to be able to handle interrupts coming in at those
 152           points; some don't and need to be caught.
 153
 154 config LOCKUP_DETECTOR
 155         bool "Detect Hard and Soft Lockups"
 156         depends on DEBUG_KERNEL && !S390
 157         help
 158           Say Y here to enable the kernel to act as a watchdog to detect
 159           hard and soft lockups.
 160
 161           Softlockups are bugs that cause the kernel to loop in kernel
 162           mode for more than 60 seconds, without giving other tasks a
 163           chance to run.  The current stack trace is displayed upon
 164           detection and the system will stay locked up.
 165
 166           Hardlockups are bugs that cause the CPU to loop in kernel mode
 167           for more than 60 seconds, without letting other interrupts have a
 168           chance to run.  The current stack trace is displayed upon detection
 169           and the system will stay locked up.
 170
 171           The overhead should be minimal.  A periodic hrtimer runs to
 172           generate interrupts and kick the watchdog task every 10-12 seconds.
 173           An NMI is generated every 60 seconds or so to check for hardlockups.
 174
 175 config HARDLOCKUP_DETECTOR
 176         def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI
 177
 178 config BOOTPARAM_SOFTLOCKUP_PANIC
 179         bool "Panic (Reboot) On Soft Lockups"
 180         depends on LOCKUP_DETECTOR
 181         help
 182           Say Y here to enable the kernel to panic on "soft lockups",
 183           which are bugs that cause the kernel to loop in kernel
 184           mode for more than 60 seconds, without giving other tasks a
 185           chance to run.
 186
 187           The panic can be used in combination with panic_timeout,
 188           to cause the system to reboot automatically after a
 189           lockup has been detected. This feature is useful for
 190           high-availability systems that have uptime guarantees and
 191           where a lockup must be resolved ASAP.
 192
 193           Say N if unsure.
 194
 195 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 196         int
 197         depends on LOCKUP_DETECTOR
 198         range 0 1
 199         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 200         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 201
 202 config DETECT_HUNG_TASK
 203         bool "Detect Hung Tasks"
 204         depends on DEBUG_KERNEL
 205         default DETECT_SOFTLOCKUP
 206         help
 207           Say Y here to enable the kernel to detect "hung tasks",
 208           which are bugs that cause the task to be stuck in
 209           uninterruptible "D" state indefinitiley.
 210
 211           When a hung task is detected, the kernel will print the
 212           current stack trace (which you should report), but the
 213           task will stay in uninterruptible state. If lockdep is
 214           enabled then all held locks will also be reported. This
 215           feature has negligible overhead.
 216
 217 config BOOTPARAM_HUNG_TASK_PANIC
 218         bool "Panic (Reboot) On Hung Tasks"
 219         depends on DETECT_HUNG_TASK
 220         help
 221           Say Y here to enable the kernel to panic on "hung tasks",
 222           which are bugs that cause the kernel to leave a task stuck
 223           in uninterruptible "D" state.
 224
 225           The panic can be used in combination with panic_timeout,
 226           to cause the system to reboot automatically after a
 227           hung task has been detected. This feature is useful for
 228           high-availability systems that have uptime guarantees and
 229           where a hung tasks must be resolved ASAP.
 230
 231           Say N if unsure.
 232
 233 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 234         int
 235         depends on DETECT_HUNG_TASK
 236         range 0 1
 237         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 238         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 239
 240 config SCHED_DEBUG
 241         bool "Collect scheduler debugging info"
 242         depends on DEBUG_KERNEL && PROC_FS
 243         default y
 244         help
 245           If you say Y here, the /proc/sched_debug file will be provided
 246           that can help debug the scheduler. The runtime overhead of this
 247           option is minimal.
 248
 249 config SCHEDSTATS
 250         bool "Collect scheduler statistics"
 251         depends on DEBUG_KERNEL && PROC_FS
 252         help
 253           If you say Y here, additional code will be inserted into the
 254           scheduler and related routines to collect statistics about
 255           scheduler behavior and provide them in /proc/schedstat.  These
 256           stats may be useful for both tuning and debugging the scheduler
 257           If you aren't debugging the scheduler or trying to tune a specific
 258           application, you can say N to avoid the very slight overhead
 259           this adds.
 260
 261 config TIMER_STATS
 262         bool "Collect kernel timers statistics"
 263         depends on DEBUG_KERNEL && PROC_FS
 264         help
 265           If you say Y here, additional code will be inserted into the
 266           timer routines to collect statistics about kernel timers being
 267           reprogrammed. The statistics can be read from /proc/timer_stats.
 268           The statistics collection is started by writing 1 to /proc/timer_stats,
 269           writing 0 stops it. This feature is useful to collect information
 270           about timer usage patterns in kernel and userspace. This feature
 271           is lightweight if enabled in the kernel config but not activated
 272           (it defaults to deactivated on bootup and will only be activated
 273           if some application like powertop activates it explicitly).
 274
 275 config DEBUG_OBJECTS
 276         bool "Debug object operations"
 277         depends on DEBUG_KERNEL
 278         help
 279           If you say Y here, additional code will be inserted into the
 280           kernel to track the life time of various objects and validate
 281           the operations on those objects.
 282
 283 config DEBUG_OBJECTS_SELFTEST
 284         bool "Debug objects selftest"
 285         depends on DEBUG_OBJECTS
 286         help
 287           This enables the selftest of the object debug code.
 288
 289 config DEBUG_OBJECTS_FREE
 290         bool "Debug objects in freed memory"
 291         depends on DEBUG_OBJECTS
 292         help
 293           This enables checks whether a k/v free operation frees an area
 294           which contains an object which has not been deactivated
 295           properly. This can make kmalloc/kfree-intensive workloads
 296           much slower.
 297
 298 config DEBUG_OBJECTS_TIMERS
 299         bool "Debug timer objects"
 300         depends on DEBUG_OBJECTS
 301         help
 302           If you say Y here, additional code will be inserted into the
 303           timer routines to track the life time of timer objects and
 304           validate the timer operations.
 305
 306 config DEBUG_OBJECTS_WORK
 307         bool "Debug work objects"
 308         depends on DEBUG_OBJECTS
 309         help
 310           If you say Y here, additional code will be inserted into the
 311           work queue routines to track the life time of work objects and
 312           validate the work operations.
 313
 314 config DEBUG_OBJECTS_RCU_HEAD
 315         bool "Debug RCU callbacks objects"
 316         depends on DEBUG_OBJECTS && PREEMPT
 317         help
 318           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 319
 320 config DEBUG_OBJECTS_ENABLE_DEFAULT
 321         int "debug_objects bootup default value (0-1)"
 322         range 0 1
 323         default "1"
 324         depends on DEBUG_OBJECTS
 325         help
 326           Debug objects boot parameter default value
 327
 328 config DEBUG_SLAB
 329         bool "Debug slab memory allocations"
 330         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 331         help
 332           Say Y here to have the kernel do limited verification on memory
 333           allocation as well as poisoning memory on free to catch use of freed
 334           memory. This can make kmalloc/kfree-intensive workloads much slower.
 335
 336 config DEBUG_SLAB_LEAK
 337         bool "Memory leak debugging"
 338         depends on DEBUG_SLAB
 339
 340 config SLUB_DEBUG_ON
 341         bool "SLUB debugging on by default"
 342         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 343         default n
 344         help
 345           Boot with debugging on by default. SLUB boots by default with
 346           the runtime debug capabilities switched off. Enabling this is
 347           equivalent to specifying the "slub_debug" parameter on boot.
 348           There is no support for more fine grained debug control like
 349           possible with slub_debug=xxx. SLUB debugging may be switched
 350           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 351           "slub_debug=-".
 352
 353 config SLUB_STATS
 354         default n
 355         bool "Enable SLUB performance statistics"
 356         depends on SLUB && SLUB_DEBUG && SYSFS
 357         help
 358           SLUB statistics are useful to debug SLUBs allocation behavior in
 359           order find ways to optimize the allocator. This should never be
 360           enabled for production use since keeping statistics slows down
 361           the allocator by a few percentage points. The slabinfo command
 362           supports the determination of the most active slabs to figure
 363           out which slabs are relevant to a particular load.
 364           Try running: slabinfo -DA
 365
 366 config DEBUG_KMEMLEAK
 367         bool "Kernel memory leak detector"
 368         depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
 369                 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE)
 370
 371         select DEBUG_FS if SYSFS
 372         select STACKTRACE if STACKTRACE_SUPPORT
 373         select KALLSYMS
 374         select CRC32
 375         help
 376           Say Y here if you want to enable the memory leak
 377           detector. The memory allocation/freeing is traced in a way
 378           similar to the Boehm's conservative garbage collector, the
 379           difference being that the orphan objects are not freed but
 380           only shown in /sys/kernel/debug/kmemleak. Enabling this
 381           feature will introduce an overhead to memory
 382           allocations. See Documentation/kmemleak.txt for more
 383           details.
 384
 385           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 386           of finding leaks due to the slab objects poisoning.
 387
 388           In order to access the kmemleak file, debugfs needs to be
 389           mounted (usually at /sys/kernel/debug).
 390
 391 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 392         int "Maximum kmemleak early log entries"
 393         depends on DEBUG_KMEMLEAK
 394         range 200 40000
 395         default 400
 396         help
 397           Kmemleak must track all the memory allocations to avoid
 398           reporting false positives. Since memory may be allocated or
 399           freed before kmemleak is initialised, an early log buffer is
 400           used to store these actions. If kmemleak reports "early log
 401           buffer exceeded", please increase this value.
 402
 403 config DEBUG_KMEMLEAK_TEST
 404         tristate "Simple test for the kernel memory leak detector"
 405         depends on DEBUG_KMEMLEAK
 406         help
 407           Say Y or M here to build a test for the kernel memory leak
 408           detector. This option enables a module that explicitly leaks
 409           memory.
 410
 411           If unsure, say N.
 412
 413 config DEBUG_KMEMLEAK_DEFAULT_OFF
 414         bool "Default kmemleak to off"
 415         depends on DEBUG_KMEMLEAK
 416         help
 417           Say Y here to disable kmemleak by default. It can then be enabled
 418           on the command line via kmemleak=on.
 419
 420 config DEBUG_PREEMPT
 421         bool "Debug preemptible kernel"
 422         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 423         default y
 424         help
 425           If you say Y here then the kernel will use a debug variant of the
 426           commonly used smp_processor_id() function and will print warnings
 427           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 428           will detect preemption count underflows.
 429
 430 config DEBUG_RT_MUTEXES
 431         bool "RT Mutex debugging, deadlock detection"
 432         depends on DEBUG_KERNEL && RT_MUTEXES
 433         help
 434          This allows rt mutex semantics violations and rt mutex related
 435          deadlocks (lockups) to be detected and reported automatically.
 436
 437 config DEBUG_PI_LIST
 438         bool
 439         default y
 440         depends on DEBUG_RT_MUTEXES
 441
 442 config RT_MUTEX_TESTER
 443         bool "Built-in scriptable tester for rt-mutexes"
 444         depends on DEBUG_KERNEL && RT_MUTEXES
 445         help
 446           This option enables a rt-mutex tester.
 447
 448 config DEBUG_SPINLOCK
 449         bool "Spinlock and rw-lock debugging: basic checks"
 450         depends on DEBUG_KERNEL
 451         help
 452           Say Y here and build SMP to catch missing spinlock initialization
 453           and certain other kinds of spinlock errors commonly made.  This is
 454           best used in conjunction with the NMI watchdog so that spinlock
 455           deadlocks are also debuggable.
 456
 457 config DEBUG_MUTEXES
 458         bool "Mutex debugging: basic checks"
 459         depends on DEBUG_KERNEL
 460         help
 461          This feature allows mutex semantics violations to be detected and
 462          reported.
 463
 464 config DEBUG_LOCK_ALLOC
 465         bool "Lock debugging: detect incorrect freeing of live locks"
 466         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 467         select DEBUG_SPINLOCK
 468         select DEBUG_MUTEXES
 469         select LOCKDEP
 470         help
 471          This feature will check whether any held lock (spinlock, rwlock,
 472          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 473          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 474          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 475          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 476          held during task exit.
 477
 478 config PROVE_LOCKING
 479         bool "Lock debugging: prove locking correctness"
 480         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 481         select LOCKDEP
 482         select DEBUG_SPINLOCK
 483         select DEBUG_MUTEXES
 484         select DEBUG_LOCK_ALLOC
 485         default n
 486         help
 487          This feature enables the kernel to prove that all locking
 488          that occurs in the kernel runtime is mathematically
 489          correct: that under no circumstance could an arbitrary (and
 490          not yet triggered) combination of observed locking
 491          sequences (on an arbitrary number of CPUs, running an
 492          arbitrary number of tasks and interrupt contexts) cause a
 493          deadlock.
 494
 495          In short, this feature enables the kernel to report locking
 496          related deadlocks before they actually occur.
 497
 498          The proof does not depend on how hard and complex a
 499          deadlock scenario would be to trigger: how many
 500          participant CPUs, tasks and irq-contexts would be needed
 501          for it to trigger. The proof also does not depend on
 502          timing: if a race and a resulting deadlock is possible
 503          theoretically (no matter how unlikely the race scenario
 504          is), it will be proven so and will immediately be
 505          reported by the kernel (once the event is observed that
 506          makes the deadlock theoretically possible).
 507
 508          If a deadlock is impossible (i.e. the locking rules, as
 509          observed by the kernel, are mathematically correct), the
 510          kernel reports nothing.
 511
 512          NOTE: this feature can also be enabled for rwlocks, mutexes
 513          and rwsems - in which case all dependencies between these
 514          different locking variants are observed and mapped too, and
 515          the proof of observed correctness is also maintained for an
 516          arbitrary combination of these separate locking variants.
 517
 518          For more details, see Documentation/lockdep-design.txt.
 519
 520 config PROVE_RCU
 521         bool "RCU debugging: prove RCU correctness"
 522         depends on PROVE_LOCKING
 523         default n
 524         help
 525          This feature enables lockdep extensions that check for correct
 526          use of RCU APIs.  This is currently under development.  Say Y
 527          if you want to debug RCU usage or help work on the PROVE_RCU
 528          feature.
 529
 530          Say N if you are unsure.
 531
 532 config PROVE_RCU_REPEATEDLY
 533         bool "RCU debugging: don't disable PROVE_RCU on first splat"
 534         depends on PROVE_RCU
 535         default n
 536         help
 537          By itself, PROVE_RCU will disable checking upon issuing the
 538          first warning (or "splat").  This feature prevents such
 539          disabling, allowing multiple RCU-lockdep warnings to be printed
 540          on a single reboot.
 541
 542 config SPARSE_RCU_POINTER
 543         bool "RCU debugging: sparse-based checks for pointer usage"
 544         default n
 545         help
 546          This feature enables the __rcu sparse annotation for
 547          RCU-protected pointers.  This annotation will cause sparse
 548          to flag any non-RCU used of annotated pointers.  This can be
 549          helpful when debugging RCU usage.  Please note that this feature
 550          is not intended to enforce code cleanliness; it is instead merely
 551          a debugging aid.
 552
 553          Say Y to make sparse flag questionable use of RCU-protected pointers
 554
 555          Say N if you are unsure.
 556
 557 config LOCKDEP
 558         bool
 559         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 560         select STACKTRACE
 561         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 562         select KALLSYMS
 563         select KALLSYMS_ALL
 564
 565 config LOCK_STAT
 566         bool "Lock usage statistics"
 567         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 568         select LOCKDEP
 569         select DEBUG_SPINLOCK
 570         select DEBUG_MUTEXES
 571         select DEBUG_LOCK_ALLOC
 572         default n
 573         help
 574          This feature enables tracking lock contention points
 575
 576          For more details, see Documentation/lockstat.txt
 577
 578          This also enables lock events required by "perf lock",
 579          subcommand of perf.
 580          If you want to use "perf lock", you also need to turn on
 581          CONFIG_EVENT_TRACING.
 582
 583          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 584          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 585
 586 config DEBUG_LOCKDEP
 587         bool "Lock dependency engine debugging"
 588         depends on DEBUG_KERNEL && LOCKDEP
 589         help
 590           If you say Y here, the lock dependency engine will do
 591           additional runtime checks to debug itself, at the price
 592           of more runtime overhead.
 593
 594 config TRACE_IRQFLAGS
 595         depends on DEBUG_KERNEL
 596         bool
 597         default y
 598         depends on TRACE_IRQFLAGS_SUPPORT
 599         depends on PROVE_LOCKING
 600
 601 config DEBUG_SPINLOCK_SLEEP
 602         bool "Spinlock debugging: sleep-inside-spinlock checking"
 603         depends on DEBUG_KERNEL
 604         help
 605           If you say Y here, various routines which may sleep will become very
 606           noisy if they are called with a spinlock held.
 607
 608 config DEBUG_LOCKING_API_SELFTESTS
 609         bool "Locking API boot-time self-tests"
 610         depends on DEBUG_KERNEL
 611         help
 612           Say Y here if you want the kernel to run a short self-test during
 613           bootup. The self-test checks whether common types of locking bugs
 614           are detected by debugging mechanisms or not. (if you disable
 615           lock debugging then those bugs wont be detected of course.)
 616           The following locking APIs are covered: spinlocks, rwlocks,
 617           mutexes and rwsems.
 618
 619 config STACKTRACE
 620         bool
 621         depends on STACKTRACE_SUPPORT
 622
 623 config DEBUG_KOBJECT
 624         bool "kobject debugging"
 625         depends on DEBUG_KERNEL
 626         help
 627           If you say Y here, some extra kobject debugging messages will be sent
 628           to the syslog.
 629
 630 config DEBUG_HIGHMEM
 631         bool "Highmem debugging"
 632         depends on DEBUG_KERNEL && HIGHMEM
 633         help
 634           This options enables addition error checking for high memory systems.
 635           Disable for production systems.
 636
 637 config DEBUG_BUGVERBOSE
 638         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 639         depends on BUG
 640         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 641                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 642         default y
 643         help
 644           Say Y here to make BUG() panics output the file name and line number
 645           of the BUG call as well as the EIP and oops trace.  This aids
 646           debugging but costs about 70-100K of memory.
 647
 648 config DEBUG_INFO
 649         bool "Compile the kernel with debug info"
 650         depends on DEBUG_KERNEL
 651         help
 652           If you say Y here the resulting kernel image will include
 653           debugging info resulting in a larger kernel image.
 654           This adds debug symbols to the kernel and modules (gcc -g), and
 655           is needed if you intend to use kernel crashdump or binary object
 656           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 657           Say Y here only if you plan to debug the kernel.
 658
 659           If unsure, say N.
 660
 661 config DEBUG_INFO_REDUCED
 662         bool "Reduce debugging information"
 663         depends on DEBUG_INFO
 664         help
 665           If you say Y here gcc is instructed to generate less debugging
 666           information for structure types. This means that tools that
 667           need full debugging information (like kgdb or systemtap) won't
 668           be happy. But if you merely need debugging information to
 669           resolve line numbers there is no loss. Advantage is that
 670           build directory object sizes shrink dramatically over a full
 671           DEBUG_INFO build and compile times are reduced too.
 672           Only works with newer gcc versions.
 673
 674 config DEBUG_VM
 675         bool "Debug VM"
 676         depends on DEBUG_KERNEL
 677         help
 678           Enable this to turn on extended checks in the virtual-memory system
 679           that may impact performance.
 680
 681           If unsure, say N.
 682
 683 config DEBUG_VIRTUAL
 684         bool "Debug VM translations"
 685         depends on DEBUG_KERNEL && X86
 686         help
 687           Enable some costly sanity checks in virtual to page code. This can
 688           catch mistakes with virt_to_page() and friends.
 689
 690           If unsure, say N.
 691
 692 config DEBUG_NOMMU_REGIONS
 693         bool "Debug the global anon/private NOMMU mapping region tree"
 694         depends on DEBUG_KERNEL && !MMU
 695         help
 696           This option causes the global tree of anonymous and private mapping
 697           regions to be regularly checked for invalid topology.
 698
 699 config DEBUG_WRITECOUNT
 700         bool "Debug filesystem writers count"
 701         depends on DEBUG_KERNEL
 702         help
 703           Enable this to catch wrong use of the writers count in struct
 704           vfsmount.  This will increase the size of each file struct by
 705           32 bits.
 706
 707           If unsure, say N.
 708
 709 config DEBUG_MEMORY_INIT
 710         bool "Debug memory initialisation" if EMBEDDED
 711         default !EMBEDDED
 712         help
 713           Enable this for additional checks during memory initialisation.
 714           The sanity checks verify aspects of the VM such as the memory model
 715           and other information provided by the architecture. Verbose
 716           information will be printed at KERN_DEBUG loglevel depending
 717           on the mminit_loglevel= command-line option.
 718
 719           If unsure, say Y
 720
 721 config DEBUG_LIST
 722         bool "Debug linked list manipulation"
 723         depends on DEBUG_KERNEL
 724         help
 725           Enable this to turn on extended checks in the linked-list
 726           walking routines.
 727
 728           If unsure, say N.
 729
 730 config DEBUG_SG
 731         bool "Debug SG table operations"
 732         depends on DEBUG_KERNEL
 733         help
 734           Enable this to turn on checks on scatter-gather tables. This can
 735           help find problems with drivers that do not properly initialize
 736           their sg tables.
 737
 738           If unsure, say N.
 739
 740 config DEBUG_NOTIFIERS
 741         bool "Debug notifier call chains"
 742         depends on DEBUG_KERNEL
 743         help
 744           Enable this to turn on sanity checking for notifier call chains.
 745           This is most useful for kernel developers to make sure that
 746           modules properly unregister themselves from notifier chains.
 747           This is a relatively cheap check but if you care about maximum
 748           performance, say N.
 749
 750 config DEBUG_CREDENTIALS
 751         bool "Debug credential management"
 752         depends on DEBUG_KERNEL
 753         help
 754           Enable this to turn on some debug checking for credential
 755           management.  The additional code keeps track of the number of
 756           pointers from task_structs to any given cred struct, and checks to
 757           see that this number never exceeds the usage count of the cred
 758           struct.
 759
 760           Furthermore, if SELinux is enabled, this also checks that the
 761           security pointer in the cred struct is never seen to be invalid.
 762
 763           If unsure, say N.
 764
 765 #
 766 # Select this config option from the architecture Kconfig, if it
 767 # it is preferred to always offer frame pointers as a config
 768 # option on the architecture (regardless of KERNEL_DEBUG):
 769 #
 770 config ARCH_WANT_FRAME_POINTERS
 771         bool
 772         help
 773
 774 config FRAME_POINTER
 775         bool "Compile the kernel with frame pointers"
 776         depends on DEBUG_KERNEL && \
 777                 (CRIS || M68K || M68KNOMMU || FRV || UML || \
 778                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 779                 ARCH_WANT_FRAME_POINTERS
 780         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 781         help
 782           If you say Y here the resulting kernel image will be slightly
 783           larger and slower, but it gives very useful debugging information
 784           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 785
 786 config BOOT_PRINTK_DELAY
 787         bool "Delay each boot printk message by N milliseconds"
 788         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 789         help
 790           This build option allows you to read kernel boot messages
 791           by inserting a short delay after each one.  The delay is
 792           specified in milliseconds on the kernel command line,
 793           using "boot_delay=N".
 794
 795           It is likely that you would also need to use "lpj=M" to preset
 796           the "loops per jiffie" value.
 797           See a previous boot log for the "lpj" value to use for your
 798           system, and then set "lpj=M" before setting "boot_delay=N".
 799           NOTE:  Using this option may adversely affect SMP systems.
 800           I.e., processors other than the first one may not boot up.
 801           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 802           what it believes to be lockup conditions.
 803
 804 config RCU_TORTURE_TEST
 805         tristate "torture tests for RCU"
 806         depends on DEBUG_KERNEL
 807         default n
 808         help
 809           This option provides a kernel module that runs torture tests
 810           on the RCU infrastructure.  The kernel module may be built
 811           after the fact on the running kernel to be tested, if desired.
 812
 813           Say Y here if you want RCU torture tests to be built into
 814           the kernel.
 815           Say M if you want the RCU torture tests to build as a module.
 816           Say N if you are unsure.
 817
 818 config RCU_TORTURE_TEST_RUNNABLE
 819         bool "torture tests for RCU runnable by default"
 820         depends on RCU_TORTURE_TEST = y
 821         default n
 822         help
 823           This option provides a way to build the RCU torture tests
 824           directly into the kernel without them starting up at boot
 825           time.  You can use /proc/sys/kernel/rcutorture_runnable
 826           to manually override this setting.  This /proc file is
 827           available only when the RCU torture tests have been built
 828           into the kernel.
 829
 830           Say Y here if you want the RCU torture tests to start during
 831           boot (you probably don't).
 832           Say N here if you want the RCU torture tests to start only
 833           after being manually enabled via /proc.
 834
 835 config RCU_CPU_STALL_DETECTOR
 836         bool "Check for stalled CPUs delaying RCU grace periods"
 837         depends on TREE_RCU || TREE_PREEMPT_RCU
 838         default y
 839         help
 840           This option causes RCU to printk information on which
 841           CPUs are delaying the current grace period, but only when
 842           the grace period extends for excessive time periods.
 843
 844           Say N if you want to disable such checks.
 845
 846           Say Y if you are unsure.
 847
 848 config RCU_CPU_STALL_VERBOSE
 849         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 850         depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
 851         default y
 852         help
 853           This option causes RCU to printk detailed per-task information
 854           for any tasks that are stalling the current RCU grace period.
 855
 856           Say N if you are unsure.
 857
 858           Say Y if you want to enable such checks.
 859
 860 config KPROBES_SANITY_TEST
 861         bool "Kprobes sanity tests"
 862         depends on DEBUG_KERNEL
 863         depends on KPROBES
 864         default n
 865         help
 866           This option provides for testing basic kprobes functionality on
 867           boot. A sample kprobe, jprobe and kretprobe are inserted and
 868           verified for functionality.
 869
 870           Say N if you are unsure.
 871
 872 config BACKTRACE_SELF_TEST
 873         tristate "Self test for the backtrace code"
 874         depends on DEBUG_KERNEL
 875         default n
 876         help
 877           This option provides a kernel module that can be used to test
 878           the kernel stack backtrace code. This option is not useful
 879           for distributions or general kernels, but only for kernel
 880           developers working on architecture code.
 881
 882           Note that if you want to also test saved backtraces, you will
 883           have to enable STACKTRACE as well.
 884
 885           Say N if you are unsure.
 886
 887 config DEBUG_BLOCK_EXT_DEVT
 888         bool "Force extended block device numbers and spread them"
 889         depends on DEBUG_KERNEL
 890         depends on BLOCK
 891         default n
 892         help
 893           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 894           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 895           YOU ARE DOING.  Distros, please enable this and fix whatever
 896           is broken.
 897
 898           Conventionally, block device numbers are allocated from
 899           predetermined contiguous area.  However, extended block area
 900           may introduce non-contiguous block device numbers.  This
 901           option forces most block device numbers to be allocated from
 902           the extended space and spreads them to discover kernel or
 903           userland code paths which assume predetermined contiguous
 904           device number allocation.
 905
 906           Note that turning on this debug option shuffles all the
 907           device numbers for all IDE and SCSI devices including libata
 908           ones, so root partition specified using device number
 909           directly (via rdev or root=MAJ:MIN) won't work anymore.
 910           Textual device names (root=/dev/sdXn) will continue to work.
 911
 912           Say N if you are unsure.
 913
 914 config DEBUG_FORCE_WEAK_PER_CPU
 915         bool "Force weak per-cpu definitions"
 916         depends on DEBUG_KERNEL
 917         help
 918           s390 and alpha require percpu variables in modules to be
 919           defined weak to work around addressing range issue which
 920           puts the following two restrictions on percpu variable
 921           definitions.
 922
 923           1. percpu symbols must be unique whether static or not
 924           2. percpu variables can't be defined inside a function
 925
 926           To ensure that generic code follows the above rules, this
 927           option forces all percpu variables to be defined as weak.
 928
 929 config LKDTM
 930         tristate "Linux Kernel Dump Test Tool Module"
 931         depends on DEBUG_FS
 932         depends on BLOCK
 933         default n
 934         help
 935         This module enables testing of the different dumping mechanisms by
 936         inducing system failures at predefined crash points.
 937         If you don't need it: say N
 938         Choose M here to compile this code as a module. The module will be
 939         called lkdtm.
 940
 941         Documentation on how to use the module can be found in
 942         Documentation/fault-injection/provoke-crashes.txt
 943
 944 config CPU_NOTIFIER_ERROR_INJECT
 945         tristate "CPU notifier error injection module"
 946         depends on HOTPLUG_CPU && DEBUG_KERNEL
 947         help
 948           This option provides a kernel module that can be used to test
 949           the error handling of the cpu notifiers
 950
 951           To compile this code as a module, choose M here: the module will
 952           be called cpu-notifier-error-inject.
 953
 954           If unsure, say N.
 955
 956 config FAULT_INJECTION
 957         bool "Fault-injection framework"
 958         depends on DEBUG_KERNEL
 959         help
 960           Provide fault-injection framework.
 961           For more details, see Documentation/fault-injection/.
 962
 963 config FAILSLAB
 964         bool "Fault-injection capability for kmalloc"
 965         depends on FAULT_INJECTION
 966         depends on SLAB || SLUB
 967         help
 968           Provide fault-injection capability for kmalloc.
 969
 970 config FAIL_PAGE_ALLOC
 971         bool "Fault-injection capabilitiy for alloc_pages()"
 972         depends on FAULT_INJECTION
 973         help
 974           Provide fault-injection capability for alloc_pages().
 975
 976 config FAIL_MAKE_REQUEST
 977         bool "Fault-injection capability for disk IO"
 978         depends on FAULT_INJECTION && BLOCK
 979         help
 980           Provide fault-injection capability for disk IO.
 981
 982 config FAIL_IO_TIMEOUT
 983         bool "Fault-injection capability for faking disk interrupts"
 984         depends on FAULT_INJECTION && BLOCK
 985         help
 986           Provide fault-injection capability on end IO handling. This
 987           will make the block layer "forget" an interrupt as configured,
 988           thus exercising the error handling.
 989
 990           Only works with drivers that use the generic timeout handling,
 991           for others it wont do anything.
 992
 993 config FAULT_INJECTION_DEBUG_FS
 994         bool "Debugfs entries for fault-injection capabilities"
 995         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 996         help
 997           Enable configuration of fault-injection capabilities via debugfs.
 998
 999 config FAULT_INJECTION_STACKTRACE_FILTER
1000         bool "stacktrace filter for fault-injection capabilities"
1001         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1002         depends on !X86_64
1003         select STACKTRACE
1004         select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
1005         help
1006           Provide stacktrace filter for fault-injection capabilities
1007
1008 config LATENCYTOP
1009         bool "Latency measuring infrastructure"
1010         depends on HAVE_LATENCYTOP_SUPPORT
1011         depends on DEBUG_KERNEL
1012         depends on STACKTRACE_SUPPORT
1013         depends on PROC_FS
1014         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
1015         select KALLSYMS
1016         select KALLSYMS_ALL
1017         select STACKTRACE
1018         select SCHEDSTATS
1019         select SCHED_DEBUG
1020         help
1021           Enable this option if you want to use the LatencyTOP tool
1022           to find out which userspace is blocking on what kernel operations.
1023
1024 config SYSCTL_SYSCALL_CHECK
1025         bool "Sysctl checks"
1026         depends on SYSCTL
1027         ---help---
1028           sys_sysctl uses binary paths that have been found challenging
1029           to properly maintain and use. This enables checks that help
1030           you to keep things correct.
1031
1032 source mm/Kconfig.debug
1033 source kernel/trace/Kconfig
1034
1035 config PROVIDE_OHCI1394_DMA_INIT
1036         bool "Remote debugging over FireWire early on boot"
1037         depends on PCI && X86
1038         help
1039           If you want to debug problems which hang or crash the kernel early
1040           on boot and the crashing machine has a FireWire port, you can use
1041           this feature to remotely access the memory of the crashed machine
1042           over FireWire. This employs remote DMA as part of the OHCI1394
1043           specification which is now the standard for FireWire controllers.
1044
1045           With remote DMA, you can monitor the printk buffer remotely using
1046           firescope and access all memory below 4GB using fireproxy from gdb.
1047           Even controlling a kernel debugger is possible using remote DMA.
1048
1049           Usage:
1050
1051           If ohci1394_dma=early is used as boot parameter, it will initialize
1052           all OHCI1394 controllers which are found in the PCI config space.
1053
1054           As all changes to the FireWire bus such as enabling and disabling
1055           devices cause a bus reset and thereby disable remote DMA for all
1056           devices, be sure to have the cable plugged and FireWire enabled on
1057           the debugging host before booting the debug target for debugging.
1058
1059           This code (~1k) is freed after boot. By then, the firewire stack
1060           in charge of the OHCI-1394 controllers should be used instead.
1061
1062           See Documentation/debugging-via-ohci1394.txt for more information.
1063
1064 config FIREWIRE_OHCI_REMOTE_DMA
1065         bool "Remote debugging over FireWire with firewire-ohci"
1066         depends on FIREWIRE_OHCI
1067         help
1068           This option lets you use the FireWire bus for remote debugging
1069           with help of the firewire-ohci driver. It enables unfiltered
1070           remote DMA in firewire-ohci.
1071           See Documentation/debugging-via-ohci1394.txt for more information.
1072
1073           If unsure, say N.
1074
1075 config BUILD_DOCSRC
1076         bool "Build targets in Documentation/ tree"
1077         depends on HEADERS_CHECK
1078         help
1079           This option attempts to build objects from the source files in the
1080           kernel Documentation/ tree.
1081
1082           Say N if you are unsure.
1083
1084 config DYNAMIC_DEBUG
1085         bool "Enable dynamic printk() support"
1086         default n
1087         depends on PRINTK
1088         depends on DEBUG_FS
1089         help
1090
1091           Compiles debug level messages into the kernel, which would not
1092           otherwise be available at runtime. These messages can then be
1093           enabled/disabled based on various levels of scope - per source file,
1094           function, module, format string, and line number. This mechanism
1095           implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1096           this compile option is a larger kernel text size of about 2%.
1097
1098           Usage:
1099
1100           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1101           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1102           filesystem must first be mounted before making use of this feature.
1103           We refer the control file as: <debugfs>/dynamic_debug/control. This
1104           file contains a list of the debug statements that can be enabled. The
1105           format for each line of the file is:
1106
1107                 filename:lineno [module]function flags format
1108
1109           filename : source file of the debug statement
1110           lineno : line number of the debug statement
1111           module : module that contains the debug statement
1112           function : function that contains the debug statement
1113           flags : 'p' means the line is turned 'on' for printing
1114           format : the format used for the debug statement
1115
1116           From a live system:
1117
1118                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1119                 # filename:lineno [module]function flags format
1120                 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1121                 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1122                 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1123
1124           Example usage:
1125
1126                 // enable the message at line 1603 of file svcsock.c
1127                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1128                                                 <debugfs>/dynamic_debug/control
1129
1130                 // enable all the messages in file svcsock.c
1131                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1132                                                 <debugfs>/dynamic_debug/control
1133
1134                 // enable all the messages in the NFS server module
1135                 nullarbor:~ # echo -n 'module nfsd +p' >
1136                                                 <debugfs>/dynamic_debug/control
1137
1138                 // enable all 12 messages in the function svc_process()
1139                 nullarbor:~ # echo -n 'func svc_process +p' >
1140                                                 <debugfs>/dynamic_debug/control
1141
1142                 // disable all 12 messages in the function svc_process()
1143                 nullarbor:~ # echo -n 'func svc_process -p' >
1144                                                 <debugfs>/dynamic_debug/control
1145
1146           See Documentation/dynamic-debug-howto.txt for additional information.
1147
1148 config DMA_API_DEBUG
1149         bool "Enable debugging of DMA-API usage"
1150         depends on HAVE_DMA_API_DEBUG
1151         help
1152           Enable this option to debug the use of the DMA API by device drivers.
1153           With this option you will be able to detect common bugs in device
1154           drivers like double-freeing of DMA mappings or freeing mappings that
1155           were never allocated.
1156           This option causes a performance degredation.  Use only if you want
1157           to debug device drivers. If unsure, say N.
1158
1159 config ATOMIC64_SELFTEST
1160         bool "Perform an atomic64_t self-test at boot"
1161         help
1162           Enable this option to test the atomic64_t functions at boot.
1163
1164           If unsure, say N.
1165
1166 source "samples/Kconfig"
1167
1168 source "lib/Kconfig.kgdb"
1169
1170 source "lib/Kconfig.kmemcheck"