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 && !MICROBLAZE
 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_INFO_REDUCED
 632         bool "Reduce debugging information"
 633         depends on DEBUG_INFO
 634         help
 635           If you say Y here gcc is instructed to generate less debugging
 636           information for structure types. This means that tools that
 637           need full debugging information (like kgdb or systemtap) won't
 638           be happy. But if you merely need debugging information to
 639           resolve line numbers there is no loss. Advantage is that
 640           build directory object sizes shrink dramatically over a full
 641           DEBUG_INFO build and compile times are reduced too.
 642           Only works with newer gcc versions.
 643
 644 config DEBUG_VM
 645         bool "Debug VM"
 646         depends on DEBUG_KERNEL
 647         help
 648           Enable this to turn on extended checks in the virtual-memory system
 649           that may impact performance.
 650
 651           If unsure, say N.
 652
 653 config DEBUG_VIRTUAL
 654         bool "Debug VM translations"
 655         depends on DEBUG_KERNEL && X86
 656         help
 657           Enable some costly sanity checks in virtual to page code. This can
 658           catch mistakes with virt_to_page() and friends.
 659
 660           If unsure, say N.
 661
 662 config DEBUG_NOMMU_REGIONS
 663         bool "Debug the global anon/private NOMMU mapping region tree"
 664         depends on DEBUG_KERNEL && !MMU
 665         help
 666           This option causes the global tree of anonymous and private mapping
 667           regions to be regularly checked for invalid topology.
 668
 669 config DEBUG_WRITECOUNT
 670         bool "Debug filesystem writers count"
 671         depends on DEBUG_KERNEL
 672         help
 673           Enable this to catch wrong use of the writers count in struct
 674           vfsmount.  This will increase the size of each file struct by
 675           32 bits.
 676
 677           If unsure, say N.
 678
 679 config DEBUG_MEMORY_INIT
 680         bool "Debug memory initialisation" if EMBEDDED
 681         default !EMBEDDED
 682         help
 683           Enable this for additional checks during memory initialisation.
 684           The sanity checks verify aspects of the VM such as the memory model
 685           and other information provided by the architecture. Verbose
 686           information will be printed at KERN_DEBUG loglevel depending
 687           on the mminit_loglevel= command-line option.
 688
 689           If unsure, say Y
 690
 691 config DEBUG_LIST
 692         bool "Debug linked list manipulation"
 693         depends on DEBUG_KERNEL
 694         help
 695           Enable this to turn on extended checks in the linked-list
 696           walking routines.
 697
 698           If unsure, say N.
 699
 700 config DEBUG_SG
 701         bool "Debug SG table operations"
 702         depends on DEBUG_KERNEL
 703         help
 704           Enable this to turn on checks on scatter-gather tables. This can
 705           help find problems with drivers that do not properly initialize
 706           their sg tables.
 707
 708           If unsure, say N.
 709
 710 config DEBUG_NOTIFIERS
 711         bool "Debug notifier call chains"
 712         depends on DEBUG_KERNEL
 713         help
 714           Enable this to turn on sanity checking for notifier call chains.
 715           This is most useful for kernel developers to make sure that
 716           modules properly unregister themselves from notifier chains.
 717           This is a relatively cheap check but if you care about maximum
 718           performance, say N.
 719
 720 config DEBUG_CREDENTIALS
 721         bool "Debug credential management"
 722         depends on DEBUG_KERNEL
 723         help
 724           Enable this to turn on some debug checking for credential
 725           management.  The additional code keeps track of the number of
 726           pointers from task_structs to any given cred struct, and checks to
 727           see that this number never exceeds the usage count of the cred
 728           struct.
 729
 730           Furthermore, if SELinux is enabled, this also checks that the
 731           security pointer in the cred struct is never seen to be invalid.
 732
 733           If unsure, say N.
 734
 735 #
 736 # Select this config option from the architecture Kconfig, if it
 737 # it is preferred to always offer frame pointers as a config
 738 # option on the architecture (regardless of KERNEL_DEBUG):
 739 #
 740 config ARCH_WANT_FRAME_POINTERS
 741         bool
 742         help
 743
 744 config FRAME_POINTER
 745         bool "Compile the kernel with frame pointers"
 746         depends on DEBUG_KERNEL && \
 747                 (CRIS || M68K || M68KNOMMU || FRV || UML || \
 748                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 749                 ARCH_WANT_FRAME_POINTERS
 750         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 751         help
 752           If you say Y here the resulting kernel image will be slightly
 753           larger and slower, but it gives very useful debugging information
 754           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 755
 756 config BOOT_PRINTK_DELAY
 757         bool "Delay each boot printk message by N milliseconds"
 758         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 759         help
 760           This build option allows you to read kernel boot messages
 761           by inserting a short delay after each one.  The delay is
 762           specified in milliseconds on the kernel command line,
 763           using "boot_delay=N".
 764
 765           It is likely that you would also need to use "lpj=M" to preset
 766           the "loops per jiffie" value.
 767           See a previous boot log for the "lpj" value to use for your
 768           system, and then set "lpj=M" before setting "boot_delay=N".
 769           NOTE:  Using this option may adversely affect SMP systems.
 770           I.e., processors other than the first one may not boot up.
 771           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 772           what it believes to be lockup conditions.
 773
 774 config RCU_TORTURE_TEST
 775         tristate "torture tests for RCU"
 776         depends on DEBUG_KERNEL
 777         default n
 778         help
 779           This option provides a kernel module that runs torture tests
 780           on the RCU infrastructure.  The kernel module may be built
 781           after the fact on the running kernel to be tested, if desired.
 782
 783           Say Y here if you want RCU torture tests to be built into
 784           the kernel.
 785           Say M if you want the RCU torture tests to build as a module.
 786           Say N if you are unsure.
 787
 788 config RCU_TORTURE_TEST_RUNNABLE
 789         bool "torture tests for RCU runnable by default"
 790         depends on RCU_TORTURE_TEST = y
 791         default n
 792         help
 793           This option provides a way to build the RCU torture tests
 794           directly into the kernel without them starting up at boot
 795           time.  You can use /proc/sys/kernel/rcutorture_runnable
 796           to manually override this setting.  This /proc file is
 797           available only when the RCU torture tests have been built
 798           into the kernel.
 799
 800           Say Y here if you want the RCU torture tests to start during
 801           boot (you probably don't).
 802           Say N here if you want the RCU torture tests to start only
 803           after being manually enabled via /proc.
 804
 805 config RCU_CPU_STALL_DETECTOR
 806         bool "Check for stalled CPUs delaying RCU grace periods"
 807         depends on TREE_RCU || TREE_PREEMPT_RCU
 808         default y
 809         help
 810           This option causes RCU to printk information on which
 811           CPUs are delaying the current grace period, but only when
 812           the grace period extends for excessive time periods.
 813
 814           Say N if you want to disable such checks.
 815
 816           Say Y if you are unsure.
 817
 818 config RCU_CPU_STALL_VERBOSE
 819         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 820         depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
 821         default y
 822         help
 823           This option causes RCU to printk detailed per-task information
 824           for any tasks that are stalling the current RCU grace period.
 825
 826           Say N if you are unsure.
 827
 828           Say Y if you want to enable such checks.
 829
 830 config KPROBES_SANITY_TEST
 831         bool "Kprobes sanity tests"
 832         depends on DEBUG_KERNEL
 833         depends on KPROBES
 834         default n
 835         help
 836           This option provides for testing basic kprobes functionality on
 837           boot. A sample kprobe, jprobe and kretprobe are inserted and
 838           verified for functionality.
 839
 840           Say N if you are unsure.
 841
 842 config BACKTRACE_SELF_TEST
 843         tristate "Self test for the backtrace code"
 844         depends on DEBUG_KERNEL
 845         default n
 846         help
 847           This option provides a kernel module that can be used to test
 848           the kernel stack backtrace code. This option is not useful
 849           for distributions or general kernels, but only for kernel
 850           developers working on architecture code.
 851
 852           Note that if you want to also test saved backtraces, you will
 853           have to enable STACKTRACE as well.
 854
 855           Say N if you are unsure.
 856
 857 config DEBUG_BLOCK_EXT_DEVT
 858         bool "Force extended block device numbers and spread them"
 859         depends on DEBUG_KERNEL
 860         depends on BLOCK
 861         default n
 862         help
 863           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 864           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 865           YOU ARE DOING.  Distros, please enable this and fix whatever
 866           is broken.
 867
 868           Conventionally, block device numbers are allocated from
 869           predetermined contiguous area.  However, extended block area
 870           may introduce non-contiguous block device numbers.  This
 871           option forces most block device numbers to be allocated from
 872           the extended space and spreads them to discover kernel or
 873           userland code paths which assume predetermined contiguous
 874           device number allocation.
 875
 876           Note that turning on this debug option shuffles all the
 877           device numbers for all IDE and SCSI devices including libata
 878           ones, so root partition specified using device number
 879           directly (via rdev or root=MAJ:MIN) won't work anymore.
 880           Textual device names (root=/dev/sdXn) will continue to work.
 881
 882           Say N if you are unsure.
 883
 884 config DEBUG_FORCE_WEAK_PER_CPU
 885         bool "Force weak per-cpu definitions"
 886         depends on DEBUG_KERNEL
 887         help
 888           s390 and alpha require percpu variables in modules to be
 889           defined weak to work around addressing range issue which
 890           puts the following two restrictions on percpu variable
 891           definitions.
 892
 893           1. percpu symbols must be unique whether static or not
 894           2. percpu variables can't be defined inside a function
 895
 896           To ensure that generic code follows the above rules, this
 897           option forces all percpu variables to be defined as weak.
 898
 899 config LKDTM
 900         tristate "Linux Kernel Dump Test Tool Module"
 901         depends on DEBUG_FS
 902         depends on BLOCK
 903         default n
 904         help
 905         This module enables testing of the different dumping mechanisms by
 906         inducing system failures at predefined crash points.
 907         If you don't need it: say N
 908         Choose M here to compile this code as a module. The module will be
 909         called lkdtm.
 910
 911         Documentation on how to use the module can be found in
 912         Documentation/fault-injection/provoke-crashes.txt
 913
 914 config CPU_NOTIFIER_ERROR_INJECT
 915         tristate "CPU notifier error injection module"
 916         depends on HOTPLUG_CPU && DEBUG_KERNEL
 917         help
 918           This option provides a kernel module that can be used to test
 919           the error handling of the cpu notifiers
 920
 921           To compile this code as a module, choose M here: the module will
 922           be called cpu-notifier-error-inject.
 923
 924           If unsure, say N.
 925
 926 config FAULT_INJECTION
 927         bool "Fault-injection framework"
 928         depends on DEBUG_KERNEL
 929         help
 930           Provide fault-injection framework.
 931           For more details, see Documentation/fault-injection/.
 932
 933 config FAILSLAB
 934         bool "Fault-injection capability for kmalloc"
 935         depends on FAULT_INJECTION
 936         depends on SLAB || SLUB
 937         help
 938           Provide fault-injection capability for kmalloc.
 939
 940 config FAIL_PAGE_ALLOC
 941         bool "Fault-injection capabilitiy for alloc_pages()"
 942         depends on FAULT_INJECTION
 943         help
 944           Provide fault-injection capability for alloc_pages().
 945
 946 config FAIL_MAKE_REQUEST
 947         bool "Fault-injection capability for disk IO"
 948         depends on FAULT_INJECTION && BLOCK
 949         help
 950           Provide fault-injection capability for disk IO.
 951
 952 config FAIL_IO_TIMEOUT
 953         bool "Fault-injection capability for faking disk interrupts"
 954         depends on FAULT_INJECTION && BLOCK
 955         help
 956           Provide fault-injection capability on end IO handling. This
 957           will make the block layer "forget" an interrupt as configured,
 958           thus exercising the error handling.
 959
 960           Only works with drivers that use the generic timeout handling,
 961           for others it wont do anything.
 962
 963 config FAULT_INJECTION_DEBUG_FS
 964         bool "Debugfs entries for fault-injection capabilities"
 965         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 966         help
 967           Enable configuration of fault-injection capabilities via debugfs.
 968
 969 config FAULT_INJECTION_STACKTRACE_FILTER
 970         bool "stacktrace filter for fault-injection capabilities"
 971         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 972         depends on !X86_64
 973         select STACKTRACE
 974         select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
 975         help
 976           Provide stacktrace filter for fault-injection capabilities
 977
 978 config LATENCYTOP
 979         bool "Latency measuring infrastructure"
 980         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
 981         select KALLSYMS
 982         select KALLSYMS_ALL
 983         select STACKTRACE
 984         select SCHEDSTATS
 985         select SCHED_DEBUG
 986         depends on HAVE_LATENCYTOP_SUPPORT
 987         help
 988           Enable this option if you want to use the LatencyTOP tool
 989           to find out which userspace is blocking on what kernel operations.
 990
 991 config SYSCTL_SYSCALL_CHECK
 992         bool "Sysctl checks"
 993         depends on SYSCTL
 994         ---help---
 995           sys_sysctl uses binary paths that have been found challenging
 996           to properly maintain and use. This enables checks that help
 997           you to keep things correct.
 998
 999 source mm/Kconfig.debug
1000 source kernel/trace/Kconfig
1001
1002 config PROVIDE_OHCI1394_DMA_INIT
1003         bool "Remote debugging over FireWire early on boot"
1004         depends on PCI && X86
1005         help
1006           If you want to debug problems which hang or crash the kernel early
1007           on boot and the crashing machine has a FireWire port, you can use
1008           this feature to remotely access the memory of the crashed machine
1009           over FireWire. This employs remote DMA as part of the OHCI1394
1010           specification which is now the standard for FireWire controllers.
1011
1012           With remote DMA, you can monitor the printk buffer remotely using
1013           firescope and access all memory below 4GB using fireproxy from gdb.
1014           Even controlling a kernel debugger is possible using remote DMA.
1015
1016           Usage:
1017
1018           If ohci1394_dma=early is used as boot parameter, it will initialize
1019           all OHCI1394 controllers which are found in the PCI config space.
1020
1021           As all changes to the FireWire bus such as enabling and disabling
1022           devices cause a bus reset and thereby disable remote DMA for all
1023           devices, be sure to have the cable plugged and FireWire enabled on
1024           the debugging host before booting the debug target for debugging.
1025
1026           This code (~1k) is freed after boot. By then, the firewire stack
1027           in charge of the OHCI-1394 controllers should be used instead.
1028
1029           See Documentation/debugging-via-ohci1394.txt for more information.
1030
1031 config FIREWIRE_OHCI_REMOTE_DMA
1032         bool "Remote debugging over FireWire with firewire-ohci"
1033         depends on FIREWIRE_OHCI
1034         help
1035           This option lets you use the FireWire bus for remote debugging
1036           with help of the firewire-ohci driver. It enables unfiltered
1037           remote DMA in firewire-ohci.
1038           See Documentation/debugging-via-ohci1394.txt for more information.
1039
1040           If unsure, say N.
1041
1042 config BUILD_DOCSRC
1043         bool "Build targets in Documentation/ tree"
1044         depends on HEADERS_CHECK
1045         help
1046           This option attempts to build objects from the source files in the
1047           kernel Documentation/ tree.
1048
1049           Say N if you are unsure.
1050
1051 config DYNAMIC_DEBUG
1052         bool "Enable dynamic printk() support"
1053         default n
1054         depends on PRINTK
1055         depends on DEBUG_FS
1056         help
1057
1058           Compiles debug level messages into the kernel, which would not
1059           otherwise be available at runtime. These messages can then be
1060           enabled/disabled based on various levels of scope - per source file,
1061           function, module, format string, and line number. This mechanism
1062           implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1063           this compile option is a larger kernel text size of about 2%.
1064
1065           Usage:
1066
1067           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1068           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1069           filesystem must first be mounted before making use of this feature.
1070           We refer the control file as: <debugfs>/dynamic_debug/control. This
1071           file contains a list of the debug statements that can be enabled. The
1072           format for each line of the file is:
1073
1074                 filename:lineno [module]function flags format
1075
1076           filename : source file of the debug statement
1077           lineno : line number of the debug statement
1078           module : module that contains the debug statement
1079           function : function that contains the debug statement
1080           flags : 'p' means the line is turned 'on' for printing
1081           format : the format used for the debug statement
1082
1083           From a live system:
1084
1085                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1086                 # filename:lineno [module]function flags format
1087                 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1088                 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1089                 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1090
1091           Example usage:
1092
1093                 // enable the message at line 1603 of file svcsock.c
1094                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1095                                                 <debugfs>/dynamic_debug/control
1096
1097                 // enable all the messages in file svcsock.c
1098                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1099                                                 <debugfs>/dynamic_debug/control
1100
1101                 // enable all the messages in the NFS server module
1102                 nullarbor:~ # echo -n 'module nfsd +p' >
1103                                                 <debugfs>/dynamic_debug/control
1104
1105                 // enable all 12 messages in the function svc_process()
1106                 nullarbor:~ # echo -n 'func svc_process +p' >
1107                                                 <debugfs>/dynamic_debug/control
1108
1109                 // disable all 12 messages in the function svc_process()
1110                 nullarbor:~ # echo -n 'func svc_process -p' >
1111                                                 <debugfs>/dynamic_debug/control
1112
1113           See Documentation/dynamic-debug-howto.txt for additional information.
1114
1115 config DMA_API_DEBUG
1116         bool "Enable debugging of DMA-API usage"
1117         depends on HAVE_DMA_API_DEBUG
1118         help
1119           Enable this option to debug the use of the DMA API by device drivers.
1120           With this option you will be able to detect common bugs in device
1121           drivers like double-freeing of DMA mappings or freeing mappings that
1122           were never allocated.
1123           This option causes a performance degredation.  Use only if you want
1124           to debug device drivers. If unsure, say N.
1125
1126 config ATOMIC64_SELFTEST
1127         bool "Perform an atomic64_t self-test at boot"
1128         help
1129           Enable this option to test the atomic64_t functions at boot.
1130
1131           If unsure, say N.
1132
1133 source "samples/Kconfig"
1134
1135 source "lib/Kconfig.kgdb"
1136
1137 source "lib/Kconfig.kmemcheck"