linux/lib/Kconfig.debug
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   1
   2config 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
  12config 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
  20config 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
  28config 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
  39config 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
  53config UNUSED_SYMBOLS
  54        bool "Enable unused/obsolete exported symbols"
  55        default y if X86
  56        help
  57          Unused but exported symbols make the kernel needlessly bigger.  For
  58          that reason most of these unused exports will soon be removed.  This
  59          option is provided temporarily to provide a transition period in case
  60          some external kernel module needs one of these symbols anyway. If you
  61          encounter such a case in your module, consider if you are actually
  62          using the right API.  (rationale: since nobody in the kernel is using
  63          this in a module, there is a pretty good chance it's actually the
  64          wrong interface to use).  If you really need the symbol, please send a
  65          mail to the linux kernel mailing list mentioning the symbol and why
  66          you really need it, and what the merge plan to the mainline kernel for
  67          your module is.
  68
  69config DEBUG_FS
  70        bool "Debug Filesystem"
  71        depends on SYSFS
  72        help
  73          debugfs is a virtual file system that kernel developers use to put
  74          debugging files into.  Enable this option to be able to read and
  75          write to these files.
  76
  77          For detailed documentation on the debugfs API, see
  78          Documentation/DocBook/filesystems.
  79
  80          If unsure, say N.
  81
  82config HEADERS_CHECK
  83        bool "Run 'make headers_check' when building vmlinux"
  84        depends on !UML
  85        help
  86          This option will extract the user-visible kernel headers whenever
  87          building the kernel, and will run basic sanity checks on them to
  88          ensure that exported files do not attempt to include files which
  89          were not exported, etc.
  90
  91          If you're making modifications to header files which are
  92          relevant for userspace, say 'Y', and check the headers
  93          exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  94          your build tree), to make sure they're suitable.
  95
  96config DEBUG_SECTION_MISMATCH
  97        bool "Enable full Section mismatch analysis"
  98        depends on UNDEFINED
  99        # This option is on purpose disabled for now.
 100        # It will be enabled when we are down to a resonable number
 101        # of section mismatch warnings (< 10 for an allyesconfig build)
 102        help
 103          The section mismatch analysis checks if there are illegal
 104          references from one section to another section.
 105          Linux will during link or during runtime drop some sections
 106          and any use of code/data previously in these sections will
 107          most likely result in an oops.
 108          In the code functions and variables are annotated with
 109          __init, __devinit etc. (see full list in include/linux/init.h)
 110          which results in the code/data being placed in specific sections.
 111          The section mismatch analysis is always done after a full
 112          kernel build but enabling this option will in addition
 113          do the following:
 114          - Add the option -fno-inline-functions-called-once to gcc
 115            When inlining a function annotated __init in a non-init
 116            function we would lose the section information and thus
 117            the analysis would not catch the illegal reference.
 118            This option tells gcc to inline less but will also
 119            result in a larger kernel.
 120          - Run the section mismatch analysis for each module/built-in.o
 121            When we run the section mismatch analysis on vmlinux.o we
 122            lose valueble information about where the mismatch was
 123            introduced.
 124            Running the analysis for each module/built-in.o file
 125            will tell where the mismatch happens much closer to the
 126            source. The drawback is that we will report the same
 127            mismatch at least twice.
 128          - Enable verbose reporting from modpost to help solving
 129            the section mismatches reported.
 130
 131config DEBUG_KERNEL
 132        bool "Kernel debugging"
 133        help
 134          Say Y here if you are developing drivers or trying to debug and
 135          identify kernel problems.
 136
 137config DEBUG_SHIRQ
 138        bool "Debug shared IRQ handlers"
 139        depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 140        help
 141          Enable this to generate a spurious interrupt as soon as a shared
 142          interrupt handler is registered, and just before one is deregistered.
 143          Drivers ought to be able to handle interrupts coming in at those
 144          points; some don't and need to be caught.
 145
 146config DETECT_SOFTLOCKUP
 147        bool "Detect Soft Lockups"
 148        depends on DEBUG_KERNEL && !S390
 149        default y
 150        help
 151          Say Y here to enable the kernel to detect "soft lockups",
 152          which are bugs that cause the kernel to loop in kernel
 153          mode for more than 60 seconds, without giving other tasks a
 154          chance to run.
 155
 156          When a soft-lockup is detected, the kernel will print the
 157          current stack trace (which you should report), but the
 158          system will stay locked up. This feature has negligible
 159          overhead.
 160
 161          (Note that "hard lockups" are separate type of bugs that
 162           can be detected via the NMI-watchdog, on platforms that
 163           support it.)
 164
 165config BOOTPARAM_SOFTLOCKUP_PANIC
 166        bool "Panic (Reboot) On Soft Lockups"
 167        depends on DETECT_SOFTLOCKUP
 168        help
 169          Say Y here to enable the kernel to panic on "soft lockups",
 170          which are bugs that cause the kernel to loop in kernel
 171          mode for more than 60 seconds, without giving other tasks a
 172          chance to run.
 173
 174          The panic can be used in combination with panic_timeout,
 175          to cause the system to reboot automatically after a
 176          lockup has been detected. This feature is useful for
 177          high-availability systems that have uptime guarantees and
 178          where a lockup must be resolved ASAP.
 179
 180          Say N if unsure.
 181
 182config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 183        int
 184        depends on DETECT_SOFTLOCKUP
 185        range 0 1
 186        default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 187        default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 188
 189config SCHED_DEBUG
 190        bool "Collect scheduler debugging info"
 191        depends on DEBUG_KERNEL && PROC_FS
 192        default y
 193        help
 194          If you say Y here, the /proc/sched_debug file will be provided
 195          that can help debug the scheduler. The runtime overhead of this
 196          option is minimal.
 197
 198config SCHEDSTATS
 199        bool "Collect scheduler statistics"
 200        depends on DEBUG_KERNEL && PROC_FS
 201        help
 202          If you say Y here, additional code will be inserted into the
 203          scheduler and related routines to collect statistics about
 204          scheduler behavior and provide them in /proc/schedstat.  These
 205          stats may be useful for both tuning and debugging the scheduler
 206          If you aren't debugging the scheduler or trying to tune a specific
 207          application, you can say N to avoid the very slight overhead
 208          this adds.
 209
 210config TIMER_STATS
 211        bool "Collect kernel timers statistics"
 212        depends on DEBUG_KERNEL && PROC_FS
 213        help
 214          If you say Y here, additional code will be inserted into the
 215          timer routines to collect statistics about kernel timers being
 216          reprogrammed. The statistics can be read from /proc/timer_stats.
 217          The statistics collection is started by writing 1 to /proc/timer_stats,
 218          writing 0 stops it. This feature is useful to collect information
 219          about timer usage patterns in kernel and userspace. This feature
 220          is lightweight if enabled in the kernel config but not activated
 221          (it defaults to deactivated on bootup and will only be activated
 222          if some application like powertop activates it explicitly).
 223
 224config DEBUG_OBJECTS
 225        bool "Debug object operations"
 226        depends on DEBUG_KERNEL
 227        help
 228          If you say Y here, additional code will be inserted into the
 229          kernel to track the life time of various objects and validate
 230          the operations on those objects.
 231
 232config DEBUG_OBJECTS_SELFTEST
 233        bool "Debug objects selftest"
 234        depends on DEBUG_OBJECTS
 235        help
 236          This enables the selftest of the object debug code.
 237
 238config DEBUG_OBJECTS_FREE
 239        bool "Debug objects in freed memory"
 240        depends on DEBUG_OBJECTS
 241        help
 242          This enables checks whether a k/v free operation frees an area
 243          which contains an object which has not been deactivated
 244          properly. This can make kmalloc/kfree-intensive workloads
 245          much slower.
 246
 247config DEBUG_OBJECTS_TIMERS
 248        bool "Debug timer objects"
 249        depends on DEBUG_OBJECTS
 250        help
 251          If you say Y here, additional code will be inserted into the
 252          timer routines to track the life time of timer objects and
 253          validate the timer operations.
 254
 255config DEBUG_SLAB
 256        bool "Debug slab memory allocations"
 257        depends on DEBUG_KERNEL && SLAB
 258        help
 259          Say Y here to have the kernel do limited verification on memory
 260          allocation as well as poisoning memory on free to catch use of freed
 261          memory. This can make kmalloc/kfree-intensive workloads much slower.
 262
 263config DEBUG_SLAB_LEAK
 264        bool "Memory leak debugging"
 265        depends on DEBUG_SLAB
 266
 267config SLUB_DEBUG_ON
 268        bool "SLUB debugging on by default"
 269        depends on SLUB && SLUB_DEBUG
 270        default n
 271        help
 272          Boot with debugging on by default. SLUB boots by default with
 273          the runtime debug capabilities switched off. Enabling this is
 274          equivalent to specifying the "slub_debug" parameter on boot.
 275          There is no support for more fine grained debug control like
 276          possible with slub_debug=xxx. SLUB debugging may be switched
 277          off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 278          "slub_debug=-".
 279
 280config SLUB_STATS
 281        default n
 282        bool "Enable SLUB performance statistics"
 283        depends on SLUB && SLUB_DEBUG && SYSFS
 284        help
 285          SLUB statistics are useful to debug SLUBs allocation behavior in
 286          order find ways to optimize the allocator. This should never be
 287          enabled for production use since keeping statistics slows down
 288          the allocator by a few percentage points. The slabinfo command
 289          supports the determination of the most active slabs to figure
 290          out which slabs are relevant to a particular load.
 291          Try running: slabinfo -DA
 292
 293config DEBUG_PREEMPT
 294        bool "Debug preemptible kernel"
 295        depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
 296        default y
 297        help
 298          If you say Y here then the kernel will use a debug variant of the
 299          commonly used smp_processor_id() function and will print warnings
 300          if kernel code uses it in a preemption-unsafe way. Also, the kernel
 301          will detect preemption count underflows.
 302
 303config DEBUG_RT_MUTEXES
 304        bool "RT Mutex debugging, deadlock detection"
 305        depends on DEBUG_KERNEL && RT_MUTEXES
 306        help
 307         This allows rt mutex semantics violations and rt mutex related
 308         deadlocks (lockups) to be detected and reported automatically.
 309
 310config DEBUG_PI_LIST
 311        bool
 312        default y
 313        depends on DEBUG_RT_MUTEXES
 314
 315config RT_MUTEX_TESTER
 316        bool "Built-in scriptable tester for rt-mutexes"
 317        depends on DEBUG_KERNEL && RT_MUTEXES
 318        help
 319          This option enables a rt-mutex tester.
 320
 321config DEBUG_SPINLOCK
 322        bool "Spinlock and rw-lock debugging: basic checks"
 323        depends on DEBUG_KERNEL
 324        help
 325          Say Y here and build SMP to catch missing spinlock initialization
 326          and certain other kinds of spinlock errors commonly made.  This is
 327          best used in conjunction with the NMI watchdog so that spinlock
 328          deadlocks are also debuggable.
 329
 330config DEBUG_MUTEXES
 331        bool "Mutex debugging: basic checks"
 332        depends on DEBUG_KERNEL
 333        help
 334         This feature allows mutex semantics violations to be detected and
 335         reported.
 336
 337config DEBUG_LOCK_ALLOC
 338        bool "Lock debugging: detect incorrect freeing of live locks"
 339        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 340        select DEBUG_SPINLOCK
 341        select DEBUG_MUTEXES
 342        select LOCKDEP
 343        help
 344         This feature will check whether any held lock (spinlock, rwlock,
 345         mutex or rwsem) is incorrectly freed by the kernel, via any of the
 346         memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 347         vfree(), etc.), whether a live lock is incorrectly reinitialized via
 348         spin_lock_init()/mutex_init()/etc., or whether there is any lock
 349         held during task exit.
 350
 351config PROVE_LOCKING
 352        bool "Lock debugging: prove locking correctness"
 353        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 354        select LOCKDEP
 355        select DEBUG_SPINLOCK
 356        select DEBUG_MUTEXES
 357        select DEBUG_LOCK_ALLOC
 358        default n
 359        help
 360         This feature enables the kernel to prove that all locking
 361         that occurs in the kernel runtime is mathematically
 362         correct: that under no circumstance could an arbitrary (and
 363         not yet triggered) combination of observed locking
 364         sequences (on an arbitrary number of CPUs, running an
 365         arbitrary number of tasks and interrupt contexts) cause a
 366         deadlock.
 367
 368         In short, this feature enables the kernel to report locking
 369         related deadlocks before they actually occur.
 370
 371         The proof does not depend on how hard and complex a
 372         deadlock scenario would be to trigger: how many
 373         participant CPUs, tasks and irq-contexts would be needed
 374         for it to trigger. The proof also does not depend on
 375         timing: if a race and a resulting deadlock is possible
 376         theoretically (no matter how unlikely the race scenario
 377         is), it will be proven so and will immediately be
 378         reported by the kernel (once the event is observed that
 379         makes the deadlock theoretically possible).
 380
 381         If a deadlock is impossible (i.e. the locking rules, as
 382         observed by the kernel, are mathematically correct), the
 383         kernel reports nothing.
 384
 385         NOTE: this feature can also be enabled for rwlocks, mutexes
 386         and rwsems - in which case all dependencies between these
 387         different locking variants are observed and mapped too, and
 388         the proof of observed correctness is also maintained for an
 389         arbitrary combination of these separate locking variants.
 390
 391         For more details, see Documentation/lockdep-design.txt.
 392
 393config LOCKDEP
 394        bool
 395        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 396        select STACKTRACE
 397        select FRAME_POINTER if !X86 && !MIPS && !PPC
 398        select KALLSYMS
 399        select KALLSYMS_ALL
 400
 401config LOCK_STAT
 402        bool "Lock usage statistics"
 403        depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 404        select LOCKDEP
 405        select DEBUG_SPINLOCK
 406        select DEBUG_MUTEXES
 407        select DEBUG_LOCK_ALLOC
 408        default n
 409        help
 410         This feature enables tracking lock contention points
 411
 412         For more details, see Documentation/lockstat.txt
 413
 414config DEBUG_LOCKDEP
 415        bool "Lock dependency engine debugging"
 416        depends on DEBUG_KERNEL && LOCKDEP
 417        help
 418          If you say Y here, the lock dependency engine will do
 419          additional runtime checks to debug itself, at the price
 420          of more runtime overhead.
 421
 422config TRACE_IRQFLAGS
 423        depends on DEBUG_KERNEL
 424        bool
 425        default y
 426        depends on TRACE_IRQFLAGS_SUPPORT
 427        depends on PROVE_LOCKING
 428
 429config DEBUG_SPINLOCK_SLEEP
 430        bool "Spinlock debugging: sleep-inside-spinlock checking"
 431        depends on DEBUG_KERNEL
 432        help
 433          If you say Y here, various routines which may sleep will become very
 434          noisy if they are called with a spinlock held.
 435
 436config DEBUG_LOCKING_API_SELFTESTS
 437        bool "Locking API boot-time self-tests"
 438        depends on DEBUG_KERNEL
 439        help
 440          Say Y here if you want the kernel to run a short self-test during
 441          bootup. The self-test checks whether common types of locking bugs
 442          are detected by debugging mechanisms or not. (if you disable
 443          lock debugging then those bugs wont be detected of course.)
 444          The following locking APIs are covered: spinlocks, rwlocks,
 445          mutexes and rwsems.
 446
 447config STACKTRACE
 448        bool
 449        depends on STACKTRACE_SUPPORT
 450
 451config DEBUG_KOBJECT
 452        bool "kobject debugging"
 453        depends on DEBUG_KERNEL
 454        help
 455          If you say Y here, some extra kobject debugging messages will be sent
 456          to the syslog. 
 457
 458config DEBUG_HIGHMEM
 459        bool "Highmem debugging"
 460        depends on DEBUG_KERNEL && HIGHMEM
 461        help
 462          This options enables addition error checking for high memory systems.
 463          Disable for production systems.
 464
 465config DEBUG_BUGVERBOSE
 466        bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 467        depends on BUG
 468        depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 469                   FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 470        default !EMBEDDED
 471        help
 472          Say Y here to make BUG() panics output the file name and line number
 473          of the BUG call as well as the EIP and oops trace.  This aids
 474          debugging but costs about 70-100K of memory.
 475
 476config DEBUG_INFO
 477        bool "Compile the kernel with debug info"
 478        depends on DEBUG_KERNEL
 479        help
 480          If you say Y here the resulting kernel image will include
 481          debugging info resulting in a larger kernel image.
 482          This adds debug symbols to the kernel and modules (gcc -g), and
 483          is needed if you intend to use kernel crashdump or binary object
 484          tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 485          Say Y here only if you plan to debug the kernel.
 486
 487          If unsure, say N.
 488
 489config DEBUG_VM
 490        bool "Debug VM"
 491        depends on DEBUG_KERNEL
 492        help
 493          Enable this to turn on extended checks in the virtual-memory system
 494          that may impact performance.
 495
 496          If unsure, say N.
 497
 498config DEBUG_VIRTUAL
 499        bool "Debug VM translations"
 500        depends on DEBUG_KERNEL && X86
 501        help
 502          Enable some costly sanity checks in virtual to page code. This can
 503          catch mistakes with virt_to_page() and friends.
 504
 505          If unsure, say N.
 506
 507config DEBUG_WRITECOUNT
 508        bool "Debug filesystem writers count"
 509        depends on DEBUG_KERNEL
 510        help
 511          Enable this to catch wrong use of the writers count in struct
 512          vfsmount.  This will increase the size of each file struct by
 513          32 bits.
 514
 515          If unsure, say N.
 516
 517config DEBUG_MEMORY_INIT
 518        bool "Debug memory initialisation" if EMBEDDED
 519        default !EMBEDDED
 520        help
 521          Enable this for additional checks during memory initialisation.
 522          The sanity checks verify aspects of the VM such as the memory model
 523          and other information provided by the architecture. Verbose
 524          information will be printed at KERN_DEBUG loglevel depending
 525          on the mminit_loglevel= command-line option.
 526
 527          If unsure, say Y
 528
 529config DEBUG_LIST
 530        bool "Debug linked list manipulation"
 531        depends on DEBUG_KERNEL
 532        help
 533          Enable this to turn on extended checks in the linked-list
 534          walking routines.
 535
 536          If unsure, say N.
 537
 538config DEBUG_SG
 539        bool "Debug SG table operations"
 540        depends on DEBUG_KERNEL
 541        help
 542          Enable this to turn on checks on scatter-gather tables. This can
 543          help find problems with drivers that do not properly initialize
 544          their sg tables.
 545
 546          If unsure, say N.
 547
 548config FRAME_POINTER
 549        bool "Compile the kernel with frame pointers"
 550        depends on DEBUG_KERNEL && \
 551                (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \
 552                 AVR32 || SUPERH || BLACKFIN || MN10300)
 553        default y if DEBUG_INFO && UML
 554        help
 555          If you say Y here the resulting kernel image will be slightly larger
 556          and slower, but it might give very useful debugging information on
 557          some architectures or if you use external debuggers.
 558          If you don't debug the kernel, you can say N.
 559
 560config BOOT_PRINTK_DELAY
 561        bool "Delay each boot printk message by N milliseconds"
 562        depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 563        help
 564          This build option allows you to read kernel boot messages
 565          by inserting a short delay after each one.  The delay is
 566          specified in milliseconds on the kernel command line,
 567          using "boot_delay=N".
 568
 569          It is likely that you would also need to use "lpj=M" to preset
 570          the "loops per jiffie" value.
 571          See a previous boot log for the "lpj" value to use for your
 572          system, and then set "lpj=M" before setting "boot_delay=N".
 573          NOTE:  Using this option may adversely affect SMP systems.
 574          I.e., processors other than the first one may not boot up.
 575          BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 576          what it believes to be lockup conditions.
 577
 578config RCU_TORTURE_TEST
 579        tristate "torture tests for RCU"
 580        depends on DEBUG_KERNEL
 581        default n
 582        help
 583          This option provides a kernel module that runs torture tests
 584          on the RCU infrastructure.  The kernel module may be built
 585          after the fact on the running kernel to be tested, if desired.
 586
 587          Say Y here if you want RCU torture tests to be built into
 588          the kernel.
 589          Say M if you want the RCU torture tests to build as a module.
 590          Say N if you are unsure.
 591
 592config RCU_TORTURE_TEST_RUNNABLE
 593        bool "torture tests for RCU runnable by default"
 594        depends on RCU_TORTURE_TEST = y
 595        default n
 596        help
 597          This option provides a way to build the RCU torture tests
 598          directly into the kernel without them starting up at boot
 599          time.  You can use /proc/sys/kernel/rcutorture_runnable
 600          to manually override this setting.  This /proc file is
 601          available only when the RCU torture tests have been built
 602          into the kernel.
 603
 604          Say Y here if you want the RCU torture tests to start during
 605          boot (you probably don't).
 606          Say N here if you want the RCU torture tests to start only
 607          after being manually enabled via /proc.
 608
 609config RCU_CPU_STALL_DETECTOR
 610        bool "Check for stalled CPUs delaying RCU grace periods"
 611        depends on CLASSIC_RCU
 612        default n
 613        help
 614          This option causes RCU to printk information on which
 615          CPUs are delaying the current grace period, but only when
 616          the grace period extends for excessive time periods.
 617
 618          Say Y if you want RCU to perform such checks.
 619
 620          Say N if you are unsure.
 621
 622config KPROBES_SANITY_TEST
 623        bool "Kprobes sanity tests"
 624        depends on DEBUG_KERNEL
 625        depends on KPROBES
 626        default n
 627        help
 628          This option provides for testing basic kprobes functionality on
 629          boot. A sample kprobe, jprobe and kretprobe are inserted and
 630          verified for functionality.
 631
 632          Say N if you are unsure.
 633
 634config BACKTRACE_SELF_TEST
 635        tristate "Self test for the backtrace code"
 636        depends on DEBUG_KERNEL
 637        default n
 638        help
 639          This option provides a kernel module that can be used to test
 640          the kernel stack backtrace code. This option is not useful
 641          for distributions or general kernels, but only for kernel
 642          developers working on architecture code.
 643
 644          Note that if you want to also test saved backtraces, you will
 645          have to enable STACKTRACE as well.
 646
 647          Say N if you are unsure.
 648
 649config DEBUG_BLOCK_EXT_DEVT
 650        bool "Force extended block device numbers and spread them"
 651        depends on DEBUG_KERNEL
 652        depends on BLOCK
 653        default n
 654        help
 655          BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 656          SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 657          YOU ARE DOING.  Distros, please enable this and fix whatever
 658          is broken.
 659
 660          Conventionally, block device numbers are allocated from
 661          predetermined contiguous area.  However, extended block area
 662          may introduce non-contiguous block device numbers.  This
 663          option forces most block device numbers to be allocated from
 664          the extended space and spreads them to discover kernel or
 665          userland code paths which assume predetermined contiguous
 666          device number allocation.
 667
 668          Note that turning on this debug option shuffles all the
 669          device numbers for all IDE and SCSI devices including libata
 670          ones, so root partition specified using device number
 671          directly (via rdev or root=MAJ:MIN) won't work anymore.
 672          Textual device names (root=/dev/sdXn) will continue to work.
 673
 674          Say N if you are unsure.
 675
 676config LKDTM
 677        tristate "Linux Kernel Dump Test Tool Module"
 678        depends on DEBUG_KERNEL
 679        depends on KPROBES
 680        depends on BLOCK
 681        default n
 682        help
 683        This module enables testing of the different dumping mechanisms by
 684        inducing system failures at predefined crash points.
 685        If you don't need it: say N
 686        Choose M here to compile this code as a module. The module will be
 687        called lkdtm.
 688
 689        Documentation on how to use the module can be found in
 690        drivers/misc/lkdtm.c
 691
 692config FAULT_INJECTION
 693        bool "Fault-injection framework"
 694        depends on DEBUG_KERNEL
 695        help
 696          Provide fault-injection framework.
 697          For more details, see Documentation/fault-injection/.
 698
 699config FAILSLAB
 700        bool "Fault-injection capability for kmalloc"
 701        depends on FAULT_INJECTION
 702        help
 703          Provide fault-injection capability for kmalloc.
 704
 705config FAIL_PAGE_ALLOC
 706        bool "Fault-injection capabilitiy for alloc_pages()"
 707        depends on FAULT_INJECTION
 708        help
 709          Provide fault-injection capability for alloc_pages().
 710
 711config FAIL_MAKE_REQUEST
 712        bool "Fault-injection capability for disk IO"
 713        depends on FAULT_INJECTION && BLOCK
 714        help
 715          Provide fault-injection capability for disk IO.
 716
 717config FAIL_IO_TIMEOUT
 718        bool "Faul-injection capability for faking disk interrupts"
 719        depends on FAULT_INJECTION && BLOCK
 720        help
 721          Provide fault-injection capability on end IO handling. This
 722          will make the block layer "forget" an interrupt as configured,
 723          thus exercising the error handling.
 724
 725          Only works with drivers that use the generic timeout handling,
 726          for others it wont do anything.
 727
 728config FAULT_INJECTION_DEBUG_FS
 729        bool "Debugfs entries for fault-injection capabilities"
 730        depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 731        help
 732          Enable configuration of fault-injection capabilities via debugfs.
 733
 734config FAULT_INJECTION_STACKTRACE_FILTER
 735        bool "stacktrace filter for fault-injection capabilities"
 736        depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 737        depends on !X86_64
 738        select STACKTRACE
 739        select FRAME_POINTER if !PPC
 740        help
 741          Provide stacktrace filter for fault-injection capabilities
 742
 743config LATENCYTOP
 744        bool "Latency measuring infrastructure"
 745        select FRAME_POINTER if !MIPS && !PPC
 746        select KALLSYMS
 747        select KALLSYMS_ALL
 748        select STACKTRACE
 749        select SCHEDSTATS
 750        select SCHED_DEBUG
 751        depends on HAVE_LATENCYTOP_SUPPORT
 752        help
 753          Enable this option if you want to use the LatencyTOP tool
 754          to find out which userspace is blocking on what kernel operations.
 755
 756config SYSCTL_SYSCALL_CHECK
 757        bool "Sysctl checks"
 758        depends on SYSCTL_SYSCALL
 759        ---help---
 760          sys_sysctl uses binary paths that have been found challenging
 761          to properly maintain and use. This enables checks that help
 762          you to keep things correct.
 763
 764source kernel/trace/Kconfig
 765
 766config PROVIDE_OHCI1394_DMA_INIT
 767        bool "Remote debugging over FireWire early on boot"
 768        depends on PCI && X86
 769        help
 770          If you want to debug problems which hang or crash the kernel early
 771          on boot and the crashing machine has a FireWire port, you can use
 772          this feature to remotely access the memory of the crashed machine
 773          over FireWire. This employs remote DMA as part of the OHCI1394
 774          specification which is now the standard for FireWire controllers.
 775
 776          With remote DMA, you can monitor the printk buffer remotely using
 777          firescope and access all memory below 4GB using fireproxy from gdb.
 778          Even controlling a kernel debugger is possible using remote DMA.
 779
 780          Usage:
 781
 782          If ohci1394_dma=early is used as boot parameter, it will initialize
 783          all OHCI1394 controllers which are found in the PCI config space.
 784
 785          As all changes to the FireWire bus such as enabling and disabling
 786          devices cause a bus reset and thereby disable remote DMA for all
 787          devices, be sure to have the cable plugged and FireWire enabled on
 788          the debugging host before booting the debug target for debugging.
 789
 790          This code (~1k) is freed after boot. By then, the firewire stack
 791          in charge of the OHCI-1394 controllers should be used instead.
 792
 793          See Documentation/debugging-via-ohci1394.txt for more information.
 794
 795config FIREWIRE_OHCI_REMOTE_DMA
 796        bool "Remote debugging over FireWire with firewire-ohci"
 797        depends on FIREWIRE_OHCI
 798        help
 799          This option lets you use the FireWire bus for remote debugging
 800          with help of the firewire-ohci driver. It enables unfiltered
 801          remote DMA in firewire-ohci.
 802          See Documentation/debugging-via-ohci1394.txt for more information.
 803
 804          If unsure, say N.
 805
 806menuconfig BUILD_DOCSRC
 807        bool "Build targets in Documentation/ tree"
 808        depends on HEADERS_CHECK
 809        help
 810          This option attempts to build objects from the source files in the
 811          kernel Documentation/ tree.
 812
 813          Say N if you are unsure.
 814
 815config DYNAMIC_PRINTK_DEBUG
 816        bool "Enable dynamic printk() call support"
 817        default n
 818        depends on PRINTK
 819        select PRINTK_DEBUG
 820        help
 821
 822          Compiles debug level messages into the kernel, which would not
 823          otherwise be available at runtime. These messages can then be
 824          enabled/disabled on a per module basis. This mechanism implicitly
 825          enables all pr_debug() and dev_dbg() calls. The impact of this
 826          compile option is a larger kernel text size of about 2%.
 827
 828          Usage:
 829
 830          Dynamic debugging is controlled by the debugfs file,
 831          dynamic_printk/modules. This file contains a list of the modules that
 832          can be enabled. The format of the file is the module name, followed
 833          by a set of flags that can be enabled. The first flag is always the
 834          'enabled' flag. For example:
 835
 836                <module_name> <enabled=0/1>
 837                                .
 838                                .
 839                                .
 840
 841          <module_name> : Name of the module in which the debug call resides
 842          <enabled=0/1> : whether the messages are enabled or not
 843
 844          From a live system:
 845
 846                snd_hda_intel enabled=0
 847                fixup enabled=0
 848                driver enabled=0
 849
 850          Enable a module:
 851
 852                $echo "set enabled=1 <module_name>" > dynamic_printk/modules
 853
 854          Disable a module:
 855
 856                $echo "set enabled=0 <module_name>" > dynamic_printk/modules
 857
 858          Enable all modules:
 859
 860                $echo "set enabled=1 all" > dynamic_printk/modules
 861
 862          Disable all modules:
 863
 864                $echo "set enabled=0 all" > dynamic_printk/modules
 865
 866          Finally, passing "dynamic_printk" at the command line enables
 867          debugging for all modules. This mode can be turned off via the above
 868          disable command.
 869
 870source "samples/Kconfig"
 871
 872source "lib/Kconfig.kgdb"
 873