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