lib/Kconfig.debug

   1
   2 config PRINTK_TIME
   3         bool "Show timing information on printks"
   4         depends on PRINTK
   5         help
   6           Selecting this option causes timing information to be
   7           included in printk output.  This allows you to measure
   8           the interval between kernel operations, including bootup
   9           operations.  This is useful for identifying long delays
  10           in kernel startup.
  11
  12 config ENABLE_WARN_DEPRECATED
  13         bool "Enable __deprecated logic"
  14         default y
  15         help
  16           Enable the __deprecated logic in the kernel build.
  17           Disable this to suppress the "warning: 'foo' is deprecated
  18           (declared at kernel/power/somefile.c:1234)" messages.
  19
  20 config ENABLE_MUST_CHECK
  21         bool "Enable __must_check logic"
  22         default y
  23         help
  24           Enable the __must_check logic in the kernel build.  Disable this to
  25           suppress the "warning: ignoring return value of 'foo', declared with
  26           attribute warn_unused_result" messages.
  27
  28 config FRAME_WARN
  29         int "Warn for stack frames larger than (needs gcc 4.4)"
  30         range 0 8192
  31         default 1024 if !64BIT
  32         default 2048 if 64BIT
  33         help
  34           Tell gcc to warn at build time for stack frames larger than this.
  35           Setting this too low will cause a lot of warnings.
  36           Setting it to 0 disables the warning.
  37           Requires gcc 4.4
  38
  39 config MAGIC_SYSRQ
  40         bool "Magic SysRq key"
  41         depends on !UML
  42         help
  43           If you say Y here, you will have some control over the system even
  44           if the system crashes for example during kernel debugging (e.g., you
  45           will be able to flush the buffer cache to disk, reboot the system
  46           immediately or dump some status information). This is accomplished
  47           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  48           also works on a serial console (on PC hardware at least), if you
  49           send a BREAK and then within 5 seconds a command keypress. The
  50           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  51           unless you really know what this hack does.
  52
  53 config STRIP_ASM_SYMS
  54         bool "Strip assembler-generated symbols during link"
  55         default n
  56         help
  57           Strip internal assembler-generated symbols during a link (symbols
  58           that look like '.Lxxx') so they don't pollute the output of
  59           get_wchan() and suchlike.
  60
  61 config UNUSED_SYMBOLS
  62         bool "Enable unused/obsolete exported symbols"
  63         default y if X86
  64         help
  65           Unused but exported symbols make the kernel needlessly bigger.  For
  66           that reason most of these unused exports will soon be removed.  This
  67           option is provided temporarily to provide a transition period in case
  68           some external kernel module needs one of these symbols anyway. If you
  69           encounter such a case in your module, consider if you are actually
  70           using the right API.  (rationale: since nobody in the kernel is using
  71           this in a module, there is a pretty good chance it's actually the
  72           wrong interface to use).  If you really need the symbol, please send a
  73           mail to the linux kernel mailing list mentioning the symbol and why
  74           you really need it, and what the merge plan to the mainline kernel for
  75           your module is.
  76
  77 config DEBUG_FS
  78         bool "Debug Filesystem"
  79         depends on SYSFS
  80         help
  81           debugfs is a virtual file system that kernel developers use to put
  82           debugging files into.  Enable this option to be able to read and
  83           write to these files.
  84
  85           For detailed documentation on the debugfs API, see
  86           Documentation/DocBook/filesystems.
  87
  88           If unsure, say N.
  89
  90 config HEADERS_CHECK
  91         bool "Run 'make headers_check' when building vmlinux"
  92         depends on !UML
  93         help
  94           This option will extract the user-visible kernel headers whenever
  95           building the kernel, and will run basic sanity checks on them to
  96           ensure that exported files do not attempt to include files which
  97           were not exported, etc.
  98
  99           If you're making modifications to header files which are
 100           relevant for userspace, say 'Y', and check the headers
 101           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 102           your build tree), to make sure they're suitable.
 103
 104 config DEBUG_SECTION_MISMATCH
 105         bool "Enable full Section mismatch analysis"
 106         depends on UNDEFINED || (BLACKFIN)
 107         default y
 108         # This option is on purpose disabled for now.
 109         # It will be enabled when we are down to a reasonable number
 110         # of section mismatch warnings (< 10 for an allyesconfig build)
 111         help
 112           The section mismatch analysis checks if there are illegal
 113           references from one section to another section.
 114           Linux will during link or during runtime drop some sections
 115           and any use of code/data previously in these sections will
 116           most likely result in an oops.
 117           In the code functions and variables are annotated with
 118           __init, __devinit etc. (see full list in include/linux/init.h)
 119           which results in the code/data being placed in specific sections.
 120           The section mismatch analysis is always done after a full
 121           kernel build but enabling this option will in addition
 122           do the following:
 123           - Add the option -fno-inline-functions-called-once to gcc
 124             When inlining a function annotated __init in a non-init
 125             function we would lose the section information and thus
 126             the analysis would not catch the illegal reference.
 127             This option tells gcc to inline less but will also
 128             result in a larger kernel.
 129           - Run the section mismatch analysis for each module/built-in.o
 130             When we run the section mismatch analysis on vmlinux.o we
 131             lose valueble information about where the mismatch was
 132             introduced.
 133             Running the analysis for each module/built-in.o file
 134             will tell where the mismatch happens much closer to the
 135             source. The drawback is that we will report the same
 136             mismatch at least twice.
 137           - Enable verbose reporting from modpost to help solving
 138             the section mismatches reported.
 139
 140 config DEBUG_KERNEL
 141         bool "Kernel debugging"
 142         help
 143           Say Y here if you are developing drivers or trying to debug and
 144           identify kernel problems.
 145
 146 config DEBUG_SHIRQ
 147         bool "Debug shared IRQ handlers"
 148         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 149         help
 150           Enable this to generate a spurious interrupt as soon as a shared
 151           interrupt handler is registered, and just before one is deregistered.
 152           Drivers ought to be able to handle interrupts coming in at those
 153           points; some don't and need to be caught.
 154
 155 config DETECT_SOFTLOCKUP
 156         bool "Detect Soft Lockups"
 157         depends on DEBUG_KERNEL && !S390
 158         default y
 159         help
 160           Say Y here to enable the kernel to detect "soft lockups",
 161           which are bugs that cause the kernel to loop in kernel
 162           mode for more than 60 seconds, without giving other tasks a
 163           chance to run.
 164
 165           When a soft-lockup is detected, the kernel will print the
 166           current stack trace (which you should report), but the
 167           system will stay locked up. This feature has negligible
 168           overhead.
 169
 170           (Note that "hard lockups" are separate type of bugs that
 171            can be detected via the NMI-watchdog, on platforms that
 172            support it.)
 173
 174 config BOOTPARAM_SOFTLOCKUP_PANIC
 175         bool "Panic (Reboot) On Soft Lockups"
 176         depends on DETECT_SOFTLOCKUP
 177         help
 178           Say Y here to enable the kernel to panic on "soft lockups",
 179           which are bugs that cause the kernel to loop in kernel
 180           mode for more than 60 seconds, without giving other tasks a
 181           chance to run.
 182
 183           The panic can be used in combination with panic_timeout,
 184           to cause the system to reboot automatically after a
 185           lockup has been detected. This feature is useful for
 186           high-availability systems that have uptime guarantees and
 187           where a lockup must be resolved ASAP.
 188
 189           Say N if unsure.
 190
 191 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 192         int
 193         depends on DETECT_SOFTLOCKUP
 194         range 0 1
 195         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 196         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 197
 198 config DETECT_HUNG_TASK
 199         bool "Detect Hung Tasks"
 200         depends on DEBUG_KERNEL
 201         default DETECT_SOFTLOCKUP
 202         help
 203           Say Y here to enable the kernel to detect "hung tasks",
 204           which are bugs that cause the task to be stuck in
 205           uninterruptible "D" state indefinitiley.
 206
 207           When a hung task is detected, the kernel will print the
 208           current stack trace (which you should report), but the
 209           task will stay in uninterruptible state. If lockdep is
 210           enabled then all held locks will also be reported. This
 211           feature has negligible overhead.
 212
 213 config BOOTPARAM_HUNG_TASK_PANIC
 214         bool "Panic (Reboot) On Hung Tasks"
 215         depends on DETECT_HUNG_TASK
 216         help
 217           Say Y here to enable the kernel to panic on "hung tasks",
 218           which are bugs that cause the kernel to leave a task stuck
 219           in uninterruptible "D" state.
 220
 221           The panic can be used in combination with panic_timeout,
 222           to cause the system to reboot automatically after a
 223           hung task has been detected. This feature is useful for
 224           high-availability systems that have uptime guarantees and
 225           where a hung tasks must be resolved ASAP.
 226
 227           Say N if unsure.
 228
 229 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 230         int
 231         depends on DETECT_HUNG_TASK
 232         range 0 1
 233         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 234         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 235
 236 config SCHED_DEBUG
 237         bool "Collect scheduler debugging info"
 238         depends on DEBUG_KERNEL && PROC_FS
 239         default y
 240         help
 241           If you say Y here, the /proc/sched_debug file will be provided
 242           that can help debug the scheduler. The runtime overhead of this
 243           option is minimal.
 244
 245 config SCHEDSTATS
 246         bool "Collect scheduler statistics"
 247         depends on DEBUG_KERNEL && PROC_FS
 248         help
 249           If you say Y here, additional code will be inserted into the
 250           scheduler and related routines to collect statistics about
 251           scheduler behavior and provide them in /proc/schedstat.  These
 252           stats may be useful for both tuning and debugging the scheduler
 253           If you aren't debugging the scheduler or trying to tune a specific
 254           application, you can say N to avoid the very slight overhead
 255           this adds.
 256
 257 config TIMER_STATS
 258         bool "Collect kernel timers statistics"
 259         depends on DEBUG_KERNEL && PROC_FS
 260         help
 261           If you say Y here, additional code will be inserted into the
 262           timer routines to collect statistics about kernel timers being
 263           reprogrammed. The statistics can be read from /proc/timer_stats.
 264           The statistics collection is started by writing 1 to /proc/timer_stats,
 265           writing 0 stops it. This feature is useful to collect information
 266           about timer usage patterns in kernel and userspace. This feature
 267           is lightweight if enabled in the kernel config but not activated
 268           (it defaults to deactivated on bootup and will only be activated
 269           if some application like powertop activates it explicitly).
 270
 271 config DEBUG_OBJECTS
 272         bool "Debug object operations"
 273         depends on DEBUG_KERNEL
 274         help
 275           If you say Y here, additional code will be inserted into the
 276           kernel to track the life time of various objects and validate
 277           the operations on those objects.
 278
 279 config DEBUG_OBJECTS_SELFTEST
 280         bool "Debug objects selftest"
 281         depends on DEBUG_OBJECTS
 282         help
 283           This enables the selftest of the object debug code.
 284
 285 config DEBUG_OBJECTS_FREE
 286         bool "Debug objects in freed memory"
 287         depends on DEBUG_OBJECTS
 288         help
 289           This enables checks whether a k/v free operation frees an area
 290           which contains an object which has not been deactivated
 291           properly. This can make kmalloc/kfree-intensive workloads
 292           much slower.
 293
 294 config DEBUG_OBJECTS_TIMERS
 295         bool "Debug timer objects"
 296         depends on DEBUG_OBJECTS
 297         help
 298           If you say Y here, additional code will be inserted into the
 299           timer routines to track the life time of timer objects and
 300           validate the timer operations.
 301
 302 config DEBUG_OBJECTS_WORK
 303         bool "Debug work objects"
 304         depends on DEBUG_OBJECTS
 305         help
 306           If you say Y here, additional code will be inserted into the
 307           work queue routines to track the life time of work objects and
 308           validate the work operations.
 309
 310 config DEBUG_OBJECTS_ENABLE_DEFAULT
 311         int "debug_objects bootup default value (0-1)"
 312         range 0 1
 313         default "1"
 314         depends on DEBUG_OBJECTS
 315         help
 316           Debug objects boot parameter default value
 317
 318 config DEBUG_SLAB
 319         bool "Debug slab memory allocations"
 320         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 321         help
 322           Say Y here to have the kernel do limited verification on memory
 323           allocation as well as poisoning memory on free to catch use of freed
 324           memory. This can make kmalloc/kfree-intensive workloads much slower.
 325
 326 config DEBUG_SLAB_LEAK
 327         bool "Memory leak debugging"
 328         depends on DEBUG_SLAB
 329
 330 config SLUB_DEBUG_ON
 331         bool "SLUB debugging on by default"
 332         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 333         default n
 334         help
 335           Boot with debugging on by default. SLUB boots by default with
 336           the runtime debug capabilities switched off. Enabling this is
 337           equivalent to specifying the "slub_debug" parameter on boot.
 338           There is no support for more fine grained debug control like
 339           possible with slub_debug=xxx. SLUB debugging may be switched
 340           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 341           "slub_debug=-".
 342
 343 config SLUB_STATS
 344         default n
 345         bool "Enable SLUB performance statistics"
 346         depends on SLUB && SLUB_DEBUG && SYSFS
 347         help
 348           SLUB statistics are useful to debug SLUBs allocation behavior in
 349           order find ways to optimize the allocator. This should never be
 350           enabled for production use since keeping statistics slows down
 351           the allocator by a few percentage points. The slabinfo command
 352           supports the determination of the most active slabs to figure
 353           out which slabs are relevant to a particular load.
 354           Try running: slabinfo -DA
 355
 356 config DEBUG_KMEMLEAK
 357         bool "Kernel memory leak detector"
 358         depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
 359                 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE)
 360
 361         select DEBUG_FS if SYSFS
 362         select STACKTRACE if STACKTRACE_SUPPORT
 363         select KALLSYMS
 364         select CRC32
 365         help
 366           Say Y here if you want to enable the memory leak
 367           detector. The memory allocation/freeing is traced in a way
 368           similar to the Boehm's conservative garbage collector, the
 369           difference being that the orphan objects are not freed but
 370           only shown in /sys/kernel/debug/kmemleak. Enabling this
 371           feature will introduce an overhead to memory
 372           allocations. See Documentation/kmemleak.txt for more
 373           details.
 374
 375           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 376           of finding leaks due to the slab objects poisoning.
 377
 378           In order to access the kmemleak file, debugfs needs to be
 379           mounted (usually at /sys/kernel/debug).
 380
 381 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 382         int "Maximum kmemleak early log entries"
 383         depends on DEBUG_KMEMLEAK
 384         range 200 40000
 385         default 400
 386         help
 387           Kmemleak must track all the memory allocations to avoid
 388           reporting false positives. Since memory may be allocated or
 389           freed before kmemleak is initialised, an early log buffer is
 390           used to store these actions. If kmemleak reports "early log
 391           buffer exceeded", please increase this value.
 392
 393 config DEBUG_KMEMLEAK_TEST
 394         tristate "Simple test for the kernel memory leak detector"
 395         depends on DEBUG_KMEMLEAK
 396         help
 397           Say Y or M here to build a test for the kernel memory leak
 398           detector. This option enables a module that explicitly leaks
 399           memory.
 400
 401           If unsure, say N.
 402
 403 config DEBUG_PREEMPT
 404         bool "Debug preemptible kernel"
 405         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 406         default y
 407         help
 408           If you say Y here then the kernel will use a debug variant of the
 409           commonly used smp_processor_id() function and will print warnings
 410           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 411           will detect preemption count underflows.
 412
 413 config DEBUG_RT_MUTEXES
 414         bool "RT Mutex debugging, deadlock detection"
 415         depends on DEBUG_KERNEL && RT_MUTEXES
 416         help
 417          This allows rt mutex semantics violations and rt mutex related
 418          deadlocks (lockups) to be detected and reported automatically.
 419
 420 config DEBUG_PI_LIST
 421         bool
 422         default y
 423         depends on DEBUG_RT_MUTEXES
 424
 425 config RT_MUTEX_TESTER
 426         bool "Built-in scriptable tester for rt-mutexes"
 427         depends on DEBUG_KERNEL && RT_MUTEXES
 428         help
 429           This option enables a rt-mutex tester.
 430
 431 config DEBUG_SPINLOCK
 432         bool "Spinlock and rw-lock debugging: basic checks"
 433         depends on DEBUG_KERNEL
 434         help
 435           Say Y here and build SMP to catch missing spinlock initialization
 436           and certain other kinds of spinlock errors commonly made.  This is
 437           best used in conjunction with the NMI watchdog so that spinlock
 438           deadlocks are also debuggable.
 439
 440 config DEBUG_MUTEXES
 441         bool "Mutex debugging: basic checks"
 442         depends on DEBUG_KERNEL
 443         help
 444          This feature allows mutex semantics violations to be detected and
 445          reported.
 446
 447 config DEBUG_LOCK_ALLOC
 448         bool "Lock debugging: detect incorrect freeing of live locks"
 449         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 450         select DEBUG_SPINLOCK
 451         select DEBUG_MUTEXES
 452         select LOCKDEP
 453         help
 454          This feature will check whether any held lock (spinlock, rwlock,
 455          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 456          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 457          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 458          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 459          held during task exit.
 460
 461 config PROVE_LOCKING
 462         bool "Lock debugging: prove locking correctness"
 463         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 464         select LOCKDEP
 465         select DEBUG_SPINLOCK
 466         select DEBUG_MUTEXES
 467         select DEBUG_LOCK_ALLOC
 468         default n
 469         help
 470          This feature enables the kernel to prove that all locking
 471          that occurs in the kernel runtime is mathematically
 472          correct: that under no circumstance could an arbitrary (and
 473          not yet triggered) combination of observed locking
 474          sequences (on an arbitrary number of CPUs, running an
 475          arbitrary number of tasks and interrupt contexts) cause a
 476          deadlock.
 477
 478          In short, this feature enables the kernel to report locking
 479          related deadlocks before they actually occur.
 480
 481          The proof does not depend on how hard and complex a
 482          deadlock scenario would be to trigger: how many
 483          participant CPUs, tasks and irq-contexts would be needed
 484          for it to trigger. The proof also does not depend on
 485          timing: if a race and a resulting deadlock is possible
 486          theoretically (no matter how unlikely the race scenario
 487          is), it will be proven so and will immediately be
 488          reported by the kernel (once the event is observed that
 489          makes the deadlock theoretically possible).
 490
 491          If a deadlock is impossible (i.e. the locking rules, as
 492          observed by the kernel, are mathematically correct), the
 493          kernel reports nothing.
 494
 495          NOTE: this feature can also be enabled for rwlocks, mutexes
 496          and rwsems - in which case all dependencies between these
 497          different locking variants are observed and mapped too, and
 498          the proof of observed correctness is also maintained for an
 499          arbitrary combination of these separate locking variants.
 500
 501          For more details, see Documentation/lockdep-design.txt.
 502
 503 config PROVE_RCU
 504         bool "RCU debugging: prove RCU correctness"
 505         depends on PROVE_LOCKING
 506         default n
 507         help
 508          This feature enables lockdep extensions that check for correct
 509          use of RCU APIs.  This is currently under development.  Say Y
 510          if you want to debug RCU usage or help work on the PROVE_RCU
 511          feature.
 512
 513          Say N if you are unsure.
 514
 515 config PROVE_RCU_REPEATEDLY
 516         bool "RCU debugging: don't disable PROVE_RCU on first splat"
 517         depends on PROVE_RCU
 518         default n
 519         help
 520          By itself, PROVE_RCU will disable checking upon issuing the
 521          first warning (or "splat").  This feature prevents such
 522          disabling, allowing multiple RCU-lockdep warnings to be printed
 523          on a single reboot.
 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 y
 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 CPU_NOTIFIER_ERROR_INJECT
 902         tristate "CPU notifier error injection module"
 903         depends on HOTPLUG_CPU && DEBUG_KERNEL
 904         help
 905           This option provides a kernel module that can be used to test
 906           the error handling of the cpu notifiers
 907
 908           To compile this code as a module, choose M here: the module will
 909           be called cpu-notifier-error-inject.
 910
 911           If unsure, say N.
 912
 913 config FAULT_INJECTION
 914         bool "Fault-injection framework"
 915         depends on DEBUG_KERNEL
 916         help
 917           Provide fault-injection framework.
 918           For more details, see Documentation/fault-injection/.
 919
 920 config FAILSLAB
 921         bool "Fault-injection capability for kmalloc"
 922         depends on FAULT_INJECTION
 923         depends on SLAB || SLUB
 924         help
 925           Provide fault-injection capability for kmalloc.
 926
 927 config FAIL_PAGE_ALLOC
 928         bool "Fault-injection capabilitiy for alloc_pages()"
 929         depends on FAULT_INJECTION
 930         help
 931           Provide fault-injection capability for alloc_pages().
 932
 933 config FAIL_MAKE_REQUEST
 934         bool "Fault-injection capability for disk IO"
 935         depends on FAULT_INJECTION && BLOCK
 936         help
 937           Provide fault-injection capability for disk IO.
 938
 939 config FAIL_IO_TIMEOUT
 940         bool "Faul-injection capability for faking disk interrupts"
 941         depends on FAULT_INJECTION && BLOCK
 942         help
 943           Provide fault-injection capability on end IO handling. This
 944           will make the block layer "forget" an interrupt as configured,
 945           thus exercising the error handling.
 946
 947           Only works with drivers that use the generic timeout handling,
 948           for others it wont do anything.
 949
 950 config FAULT_INJECTION_DEBUG_FS
 951         bool "Debugfs entries for fault-injection capabilities"
 952         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 953         help
 954           Enable configuration of fault-injection capabilities via debugfs.
 955
 956 config FAULT_INJECTION_STACKTRACE_FILTER
 957         bool "stacktrace filter for fault-injection capabilities"
 958         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 959         depends on !X86_64
 960         select STACKTRACE
 961         select FRAME_POINTER if !PPC && !S390
 962         help
 963           Provide stacktrace filter for fault-injection capabilities
 964
 965 config LATENCYTOP
 966         bool "Latency measuring infrastructure"
 967         select FRAME_POINTER if !MIPS && !PPC && !S390
 968         select KALLSYMS
 969         select KALLSYMS_ALL
 970         select STACKTRACE
 971         select SCHEDSTATS
 972         select SCHED_DEBUG
 973         depends on HAVE_LATENCYTOP_SUPPORT
 974         help
 975           Enable this option if you want to use the LatencyTOP tool
 976           to find out which userspace is blocking on what kernel operations.
 977
 978 config SYSCTL_SYSCALL_CHECK
 979         bool "Sysctl checks"
 980         depends on SYSCTL
 981         ---help---
 982           sys_sysctl uses binary paths that have been found challenging
 983           to properly maintain and use. This enables checks that help
 984           you to keep things correct.
 985
 986 source mm/Kconfig.debug
 987 source kernel/trace/Kconfig
 988
 989 config PROVIDE_OHCI1394_DMA_INIT
 990         bool "Remote debugging over FireWire early on boot"
 991         depends on PCI && X86
 992         help
 993           If you want to debug problems which hang or crash the kernel early
 994           on boot and the crashing machine has a FireWire port, you can use
 995           this feature to remotely access the memory of the crashed machine
 996           over FireWire. This employs remote DMA as part of the OHCI1394
 997           specification which is now the standard for FireWire controllers.
 998
 999           With remote DMA, you can monitor the printk buffer remotely using
1000           firescope and access all memory below 4GB using fireproxy from gdb.
1001           Even controlling a kernel debugger is possible using remote DMA.
1002
1003           Usage:
1004
1005           If ohci1394_dma=early is used as boot parameter, it will initialize
1006           all OHCI1394 controllers which are found in the PCI config space.
1007
1008           As all changes to the FireWire bus such as enabling and disabling
1009           devices cause a bus reset and thereby disable remote DMA for all
1010           devices, be sure to have the cable plugged and FireWire enabled on
1011           the debugging host before booting the debug target for debugging.
1012
1013           This code (~1k) is freed after boot. By then, the firewire stack
1014           in charge of the OHCI-1394 controllers should be used instead.
1015
1016           See Documentation/debugging-via-ohci1394.txt for more information.
1017
1018 config FIREWIRE_OHCI_REMOTE_DMA
1019         bool "Remote debugging over FireWire with firewire-ohci"
1020         depends on FIREWIRE_OHCI
1021         help
1022           This option lets you use the FireWire bus for remote debugging
1023           with help of the firewire-ohci driver. It enables unfiltered
1024           remote DMA in firewire-ohci.
1025           See Documentation/debugging-via-ohci1394.txt for more information.
1026
1027           If unsure, say N.
1028
1029 config BUILD_DOCSRC
1030         bool "Build targets in Documentation/ tree"
1031         depends on HEADERS_CHECK
1032         help
1033           This option attempts to build objects from the source files in the
1034           kernel Documentation/ tree.
1035
1036           Say N if you are unsure.
1037
1038 config DYNAMIC_DEBUG
1039         bool "Enable dynamic printk() support"
1040         default n
1041         depends on PRINTK
1042         depends on DEBUG_FS
1043         help
1044
1045           Compiles debug level messages into the kernel, which would not
1046           otherwise be available at runtime. These messages can then be
1047           enabled/disabled based on various levels of scope - per source file,
1048           function, module, format string, and line number. This mechanism
1049           implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1050           this compile option is a larger kernel text size of about 2%.
1051
1052           Usage:
1053
1054           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1055           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1056           filesystem must first be mounted before making use of this feature.
1057           We refer the control file as: <debugfs>/dynamic_debug/control. This
1058           file contains a list of the debug statements that can be enabled. The
1059           format for each line of the file is:
1060
1061                 filename:lineno [module]function flags format
1062
1063           filename : source file of the debug statement
1064           lineno : line number of the debug statement
1065           module : module that contains the debug statement
1066           function : function that contains the debug statement
1067           flags : 'p' means the line is turned 'on' for printing
1068           format : the format used for the debug statement
1069
1070           From a live system:
1071
1072                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1073                 # filename:lineno [module]function flags format
1074                 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1075                 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1076                 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1077
1078           Example usage:
1079
1080                 // enable the message at line 1603 of file svcsock.c
1081                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1082                                                 <debugfs>/dynamic_debug/control
1083
1084                 // enable all the messages in file svcsock.c
1085                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1086                                                 <debugfs>/dynamic_debug/control
1087
1088                 // enable all the messages in the NFS server module
1089                 nullarbor:~ # echo -n 'module nfsd +p' >
1090                                                 <debugfs>/dynamic_debug/control
1091
1092                 // enable all 12 messages in the function svc_process()
1093                 nullarbor:~ # echo -n 'func svc_process +p' >
1094                                                 <debugfs>/dynamic_debug/control
1095
1096                 // disable all 12 messages in the function svc_process()
1097                 nullarbor:~ # echo -n 'func svc_process -p' >
1098                                                 <debugfs>/dynamic_debug/control
1099
1100           See Documentation/dynamic-debug-howto.txt for additional information.
1101
1102 config DMA_API_DEBUG
1103         bool "Enable debugging of DMA-API usage"
1104         depends on HAVE_DMA_API_DEBUG
1105         help
1106           Enable this option to debug the use of the DMA API by device drivers.
1107           With this option you will be able to detect common bugs in device
1108           drivers like double-freeing of DMA mappings or freeing mappings that
1109           were never allocated.
1110           This option causes a performance degredation.  Use only if you want
1111           to debug device drivers. If unsure, say N.
1112
1113 config ATOMIC64_SELFTEST
1114         bool "Perform an atomic64_t self-test at boot"
1115         help
1116           Enable this option to test the atomic64_t functions at boot.
1117
1118           If unsure, say N.
1119
1120 source "samples/Kconfig"
1121
1122 source "lib/Kconfig.kgdb"
1123
1124 source "lib/Kconfig.kmemcheck"