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