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