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