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