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 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
  69 config 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
  82 config 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
  96 config 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
 131 config 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
 137 config 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
 146 config 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
 165 config 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
 182 config 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
 189 config 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
 198 config 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
 210 config 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
 224 config 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
 232 config 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
 238 config 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
 247 config 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
 255 config DEBUG_OBJECTS_ENABLE_DEFAULT
 256         int "debug_objects bootup default value (0-1)"
 257         range 0 1
 258         default "1"
 259         depends on DEBUG_OBJECTS
 260         help
 261           Debug objects boot parameter default value
 262
 263 config DEBUG_SLAB
 264         bool "Debug slab memory allocations"
 265         depends on DEBUG_KERNEL && SLAB
 266         help
 267           Say Y here to have the kernel do limited verification on memory
 268           allocation as well as poisoning memory on free to catch use of freed
 269           memory. This can make kmalloc/kfree-intensive workloads much slower.
 270
 271 config DEBUG_SLAB_LEAK
 272         bool "Memory leak debugging"
 273         depends on DEBUG_SLAB
 274
 275 config SLUB_DEBUG_ON
 276         bool "SLUB debugging on by default"
 277         depends on SLUB && SLUB_DEBUG
 278         default n
 279         help
 280           Boot with debugging on by default. SLUB boots by default with
 281           the runtime debug capabilities switched off. Enabling this is
 282           equivalent to specifying the "slub_debug" parameter on boot.
 283           There is no support for more fine grained debug control like
 284           possible with slub_debug=xxx. SLUB debugging may be switched
 285           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 286           "slub_debug=-".
 287
 288 config SLUB_STATS
 289         default n
 290         bool "Enable SLUB performance statistics"
 291         depends on SLUB && SLUB_DEBUG && SYSFS
 292         help
 293           SLUB statistics are useful to debug SLUBs allocation behavior in
 294           order find ways to optimize the allocator. This should never be
 295           enabled for production use since keeping statistics slows down
 296           the allocator by a few percentage points. The slabinfo command
 297           supports the determination of the most active slabs to figure
 298           out which slabs are relevant to a particular load.
 299           Try running: slabinfo -DA
 300
 301 config DEBUG_PREEMPT
 302         bool "Debug preemptible kernel"
 303         depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
 304         default y
 305         help
 306           If you say Y here then the kernel will use a debug variant of the
 307           commonly used smp_processor_id() function and will print warnings
 308           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 309           will detect preemption count underflows.
 310
 311 config DEBUG_RT_MUTEXES
 312         bool "RT Mutex debugging, deadlock detection"
 313         depends on DEBUG_KERNEL && RT_MUTEXES
 314         help
 315          This allows rt mutex semantics violations and rt mutex related
 316          deadlocks (lockups) to be detected and reported automatically.
 317
 318 config DEBUG_PI_LIST
 319         bool
 320         default y
 321         depends on DEBUG_RT_MUTEXES
 322
 323 config RT_MUTEX_TESTER
 324         bool "Built-in scriptable tester for rt-mutexes"
 325         depends on DEBUG_KERNEL && RT_MUTEXES
 326         help
 327           This option enables a rt-mutex tester.
 328
 329 config DEBUG_SPINLOCK
 330         bool "Spinlock and rw-lock debugging: basic checks"
 331         depends on DEBUG_KERNEL
 332         help
 333           Say Y here and build SMP to catch missing spinlock initialization
 334           and certain other kinds of spinlock errors commonly made.  This is
 335           best used in conjunction with the NMI watchdog so that spinlock
 336           deadlocks are also debuggable.
 337
 338 config DEBUG_MUTEXES
 339         bool "Mutex debugging: basic checks"
 340         depends on DEBUG_KERNEL
 341         help
 342          This feature allows mutex semantics violations to be detected and
 343          reported.
 344
 345 config DEBUG_LOCK_ALLOC
 346         bool "Lock debugging: detect incorrect freeing of live locks"
 347         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 348         select DEBUG_SPINLOCK
 349         select DEBUG_MUTEXES
 350         select LOCKDEP
 351         help
 352          This feature will check whether any held lock (spinlock, rwlock,
 353          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 354          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 355          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 356          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 357          held during task exit.
 358
 359 config PROVE_LOCKING
 360         bool "Lock debugging: prove locking correctness"
 361         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 362         select LOCKDEP
 363         select DEBUG_SPINLOCK
 364         select DEBUG_MUTEXES
 365         select DEBUG_LOCK_ALLOC
 366         default n
 367         help
 368          This feature enables the kernel to prove that all locking
 369          that occurs in the kernel runtime is mathematically
 370          correct: that under no circumstance could an arbitrary (and
 371          not yet triggered) combination of observed locking
 372          sequences (on an arbitrary number of CPUs, running an
 373          arbitrary number of tasks and interrupt contexts) cause a
 374          deadlock.
 375
 376          In short, this feature enables the kernel to report locking
 377          related deadlocks before they actually occur.
 378
 379          The proof does not depend on how hard and complex a
 380          deadlock scenario would be to trigger: how many
 381          participant CPUs, tasks and irq-contexts would be needed
 382          for it to trigger. The proof also does not depend on
 383          timing: if a race and a resulting deadlock is possible
 384          theoretically (no matter how unlikely the race scenario
 385          is), it will be proven so and will immediately be
 386          reported by the kernel (once the event is observed that
 387          makes the deadlock theoretically possible).
 388
 389          If a deadlock is impossible (i.e. the locking rules, as
 390          observed by the kernel, are mathematically correct), the
 391          kernel reports nothing.
 392
 393          NOTE: this feature can also be enabled for rwlocks, mutexes
 394          and rwsems - in which case all dependencies between these
 395          different locking variants are observed and mapped too, and
 396          the proof of observed correctness is also maintained for an
 397          arbitrary combination of these separate locking variants.
 398
 399          For more details, see Documentation/lockdep-design.txt.
 400
 401 config LOCKDEP
 402         bool
 403         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 404         select STACKTRACE
 405         select FRAME_POINTER if !X86 && !MIPS && !PPC
 406         select KALLSYMS
 407         select KALLSYMS_ALL
 408
 409 config LOCK_STAT
 410         bool "Lock usage statistics"
 411         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 412         select LOCKDEP
 413         select DEBUG_SPINLOCK
 414         select DEBUG_MUTEXES
 415         select DEBUG_LOCK_ALLOC
 416         default n
 417         help
 418          This feature enables tracking lock contention points
 419
 420          For more details, see Documentation/lockstat.txt
 421
 422 config DEBUG_LOCKDEP
 423         bool "Lock dependency engine debugging"
 424         depends on DEBUG_KERNEL && LOCKDEP
 425         help
 426           If you say Y here, the lock dependency engine will do
 427           additional runtime checks to debug itself, at the price
 428           of more runtime overhead.
 429
 430 config TRACE_IRQFLAGS
 431         depends on DEBUG_KERNEL
 432         bool
 433         default y
 434         depends on TRACE_IRQFLAGS_SUPPORT
 435         depends on PROVE_LOCKING
 436
 437 config DEBUG_SPINLOCK_SLEEP
 438         bool "Spinlock debugging: sleep-inside-spinlock checking"
 439         depends on DEBUG_KERNEL
 440         help
 441           If you say Y here, various routines which may sleep will become very
 442           noisy if they are called with a spinlock held.
 443
 444 config DEBUG_LOCKING_API_SELFTESTS
 445         bool "Locking API boot-time self-tests"
 446         depends on DEBUG_KERNEL
 447         help
 448           Say Y here if you want the kernel to run a short self-test during
 449           bootup. The self-test checks whether common types of locking bugs
 450           are detected by debugging mechanisms or not. (if you disable
 451           lock debugging then those bugs wont be detected of course.)
 452           The following locking APIs are covered: spinlocks, rwlocks,
 453           mutexes and rwsems.
 454
 455 config STACKTRACE
 456         bool
 457         depends on STACKTRACE_SUPPORT
 458
 459 config DEBUG_KOBJECT
 460         bool "kobject debugging"
 461         depends on DEBUG_KERNEL
 462         help
 463           If you say Y here, some extra kobject debugging messages will be sent
 464           to the syslog.
 465
 466 config DEBUG_HIGHMEM
 467         bool "Highmem debugging"
 468         depends on DEBUG_KERNEL && HIGHMEM
 469         help
 470           This options enables addition error checking for high memory systems.
 471           Disable for production systems.
 472
 473 config DEBUG_BUGVERBOSE
 474         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 475         depends on BUG
 476         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 477                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 478         default !EMBEDDED
 479         help
 480           Say Y here to make BUG() panics output the file name and line number
 481           of the BUG call as well as the EIP and oops trace.  This aids
 482           debugging but costs about 70-100K of memory.
 483
 484 config DEBUG_INFO
 485         bool "Compile the kernel with debug info"
 486         depends on DEBUG_KERNEL
 487         help
 488           If you say Y here the resulting kernel image will include
 489           debugging info resulting in a larger kernel image.
 490           This adds debug symbols to the kernel and modules (gcc -g), and
 491           is needed if you intend to use kernel crashdump or binary object
 492           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 493           Say Y here only if you plan to debug the kernel.
 494
 495           If unsure, say N.
 496
 497 config DEBUG_VM
 498         bool "Debug VM"
 499         depends on DEBUG_KERNEL
 500         help
 501           Enable this to turn on extended checks in the virtual-memory system
 502           that may impact performance.
 503
 504           If unsure, say N.
 505
 506 config DEBUG_VIRTUAL
 507         bool "Debug VM translations"
 508         depends on DEBUG_KERNEL && X86
 509         help
 510           Enable some costly sanity checks in virtual to page code. This can
 511           catch mistakes with virt_to_page() and friends.
 512
 513           If unsure, say N.
 514
 515 config DEBUG_WRITECOUNT
 516         bool "Debug filesystem writers count"
 517         depends on DEBUG_KERNEL
 518         help
 519           Enable this to catch wrong use of the writers count in struct
 520           vfsmount.  This will increase the size of each file struct by
 521           32 bits.
 522
 523           If unsure, say N.
 524
 525 config DEBUG_MEMORY_INIT
 526         bool "Debug memory initialisation" if EMBEDDED
 527         default !EMBEDDED
 528         help
 529           Enable this for additional checks during memory initialisation.
 530           The sanity checks verify aspects of the VM such as the memory model
 531           and other information provided by the architecture. Verbose
 532           information will be printed at KERN_DEBUG loglevel depending
 533           on the mminit_loglevel= command-line option.
 534
 535           If unsure, say Y
 536
 537 config DEBUG_LIST
 538         bool "Debug linked list manipulation"
 539         depends on DEBUG_KERNEL
 540         help
 541           Enable this to turn on extended checks in the linked-list
 542           walking routines.
 543
 544           If unsure, say N.
 545
 546 config DEBUG_SG
 547         bool "Debug SG table operations"
 548         depends on DEBUG_KERNEL
 549         help
 550           Enable this to turn on checks on scatter-gather tables. This can
 551           help find problems with drivers that do not properly initialize
 552           their sg tables.
 553
 554           If unsure, say N.
 555
 556 config DEBUG_NOTIFIERS
 557         bool "Debug notifier call chains"
 558         depends on DEBUG_KERNEL
 559         help
 560           Enable this to turn on sanity checking for notifier call chains.
 561           This is most useful for kernel developers to make sure that
 562           modules properly unregister themselves from notifier chains.
 563           This is a relatively cheap check but if you care about maximum
 564           performance, say N.
 565
 566 config FRAME_POINTER
 567         bool "Compile the kernel with frame pointers"
 568         depends on DEBUG_KERNEL && \
 569                 (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \
 570                  AVR32 || SUPERH || BLACKFIN || MN10300)
 571         default y if DEBUG_INFO && UML
 572         help
 573           If you say Y here the resulting kernel image will be slightly larger
 574           and slower, but it might give very useful debugging information on
 575           some architectures or if you use external debuggers.
 576           If you don't debug the kernel, you can say N.
 577
 578 config BOOT_PRINTK_DELAY
 579         bool "Delay each boot printk message by N milliseconds"
 580         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 581         help
 582           This build option allows you to read kernel boot messages
 583           by inserting a short delay after each one.  The delay is
 584           specified in milliseconds on the kernel command line,
 585           using "boot_delay=N".
 586
 587           It is likely that you would also need to use "lpj=M" to preset
 588           the "loops per jiffie" value.
 589           See a previous boot log for the "lpj" value to use for your
 590           system, and then set "lpj=M" before setting "boot_delay=N".
 591           NOTE:  Using this option may adversely affect SMP systems.
 592           I.e., processors other than the first one may not boot up.
 593           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 594           what it believes to be lockup conditions.
 595
 596 config RCU_TORTURE_TEST
 597         tristate "torture tests for RCU"
 598         depends on DEBUG_KERNEL
 599         default n
 600         help
 601           This option provides a kernel module that runs torture tests
 602           on the RCU infrastructure.  The kernel module may be built
 603           after the fact on the running kernel to be tested, if desired.
 604
 605           Say Y here if you want RCU torture tests to be built into
 606           the kernel.
 607           Say M if you want the RCU torture tests to build as a module.
 608           Say N if you are unsure.
 609
 610 config RCU_TORTURE_TEST_RUNNABLE
 611         bool "torture tests for RCU runnable by default"
 612         depends on RCU_TORTURE_TEST = y
 613         default n
 614         help
 615           This option provides a way to build the RCU torture tests
 616           directly into the kernel without them starting up at boot
 617           time.  You can use /proc/sys/kernel/rcutorture_runnable
 618           to manually override this setting.  This /proc file is
 619           available only when the RCU torture tests have been built
 620           into the kernel.
 621
 622           Say Y here if you want the RCU torture tests to start during
 623           boot (you probably don't).
 624           Say N here if you want the RCU torture tests to start only
 625           after being manually enabled via /proc.
 626
 627 config RCU_CPU_STALL_DETECTOR
 628         bool "Check for stalled CPUs delaying RCU grace periods"
 629         depends on CLASSIC_RCU
 630         default n
 631         help
 632           This option causes RCU to printk information on which
 633           CPUs are delaying the current grace period, but only when
 634           the grace period extends for excessive time periods.
 635
 636           Say Y if you want RCU to perform such checks.
 637
 638           Say N if you are unsure.
 639
 640 config RCU_CPU_STALL_DETECTOR
 641         bool "Check for stalled CPUs delaying RCU grace periods"
 642         depends on CLASSIC_RCU || TREE_RCU
 643         default n
 644         help
 645           This option causes RCU to printk information on which
 646           CPUs are delaying the current grace period, but only when
 647           the grace period extends for excessive time periods.
 648
 649           Say Y if you want RCU to perform such checks.
 650
 651           Say N if you are unsure.
 652
 653 config KPROBES_SANITY_TEST
 654         bool "Kprobes sanity tests"
 655         depends on DEBUG_KERNEL
 656         depends on KPROBES
 657         default n
 658         help
 659           This option provides for testing basic kprobes functionality on
 660           boot. A sample kprobe, jprobe and kretprobe are inserted and
 661           verified for functionality.
 662
 663           Say N if you are unsure.
 664
 665 config BACKTRACE_SELF_TEST
 666         tristate "Self test for the backtrace code"
 667         depends on DEBUG_KERNEL
 668         default n
 669         help
 670           This option provides a kernel module that can be used to test
 671           the kernel stack backtrace code. This option is not useful
 672           for distributions or general kernels, but only for kernel
 673           developers working on architecture code.
 674
 675           Note that if you want to also test saved backtraces, you will
 676           have to enable STACKTRACE as well.
 677
 678           Say N if you are unsure.
 679
 680 config DEBUG_BLOCK_EXT_DEVT
 681         bool "Force extended block device numbers and spread them"
 682         depends on DEBUG_KERNEL
 683         depends on BLOCK
 684         default n
 685         help
 686           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 687           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 688           YOU ARE DOING.  Distros, please enable this and fix whatever
 689           is broken.
 690
 691           Conventionally, block device numbers are allocated from
 692           predetermined contiguous area.  However, extended block area
 693           may introduce non-contiguous block device numbers.  This
 694           option forces most block device numbers to be allocated from
 695           the extended space and spreads them to discover kernel or
 696           userland code paths which assume predetermined contiguous
 697           device number allocation.
 698
 699           Note that turning on this debug option shuffles all the
 700           device numbers for all IDE and SCSI devices including libata
 701           ones, so root partition specified using device number
 702           directly (via rdev or root=MAJ:MIN) won't work anymore.
 703           Textual device names (root=/dev/sdXn) will continue to work.
 704
 705           Say N if you are unsure.
 706
 707 config LKDTM
 708         tristate "Linux Kernel Dump Test Tool Module"
 709         depends on DEBUG_KERNEL
 710         depends on KPROBES
 711         depends on BLOCK
 712         default n
 713         help
 714         This module enables testing of the different dumping mechanisms by
 715         inducing system failures at predefined crash points.
 716         If you don't need it: say N
 717         Choose M here to compile this code as a module. The module will be
 718         called lkdtm.
 719
 720         Documentation on how to use the module can be found in
 721         drivers/misc/lkdtm.c
 722
 723 config FAULT_INJECTION
 724         bool "Fault-injection framework"
 725         depends on DEBUG_KERNEL
 726         help
 727           Provide fault-injection framework.
 728           For more details, see Documentation/fault-injection/.
 729
 730 config FAILSLAB
 731         bool "Fault-injection capability for kmalloc"
 732         depends on FAULT_INJECTION
 733         depends on SLAB || SLUB
 734         help
 735           Provide fault-injection capability for kmalloc.
 736
 737 config FAIL_PAGE_ALLOC
 738         bool "Fault-injection capabilitiy for alloc_pages()"
 739         depends on FAULT_INJECTION
 740         help
 741           Provide fault-injection capability for alloc_pages().
 742
 743 config FAIL_MAKE_REQUEST
 744         bool "Fault-injection capability for disk IO"
 745         depends on FAULT_INJECTION && BLOCK
 746         help
 747           Provide fault-injection capability for disk IO.
 748
 749 config FAIL_IO_TIMEOUT
 750         bool "Faul-injection capability for faking disk interrupts"
 751         depends on FAULT_INJECTION && BLOCK
 752         help
 753           Provide fault-injection capability on end IO handling. This
 754           will make the block layer "forget" an interrupt as configured,
 755           thus exercising the error handling.
 756
 757           Only works with drivers that use the generic timeout handling,
 758           for others it wont do anything.
 759
 760 config FAULT_INJECTION_DEBUG_FS
 761         bool "Debugfs entries for fault-injection capabilities"
 762         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 763         help
 764           Enable configuration of fault-injection capabilities via debugfs.
 765
 766 config FAULT_INJECTION_STACKTRACE_FILTER
 767         bool "stacktrace filter for fault-injection capabilities"
 768         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 769         depends on !X86_64
 770         select STACKTRACE
 771         select FRAME_POINTER if !PPC
 772         help
 773           Provide stacktrace filter for fault-injection capabilities
 774
 775 config LATENCYTOP
 776         bool "Latency measuring infrastructure"
 777         select FRAME_POINTER if !MIPS && !PPC
 778         select KALLSYMS
 779         select KALLSYMS_ALL
 780         select STACKTRACE
 781         select SCHEDSTATS
 782         select SCHED_DEBUG
 783         depends on HAVE_LATENCYTOP_SUPPORT
 784         help
 785           Enable this option if you want to use the LatencyTOP tool
 786           to find out which userspace is blocking on what kernel operations.
 787
 788 config SYSCTL_SYSCALL_CHECK
 789         bool "Sysctl checks"
 790         depends on SYSCTL_SYSCALL
 791         ---help---
 792           sys_sysctl uses binary paths that have been found challenging
 793           to properly maintain and use. This enables checks that help
 794           you to keep things correct.
 795
 796 source kernel/trace/Kconfig
 797
 798 config PROVIDE_OHCI1394_DMA_INIT
 799         bool "Remote debugging over FireWire early on boot"
 800         depends on PCI && X86
 801         help
 802           If you want to debug problems which hang or crash the kernel early
 803           on boot and the crashing machine has a FireWire port, you can use
 804           this feature to remotely access the memory of the crashed machine
 805           over FireWire. This employs remote DMA as part of the OHCI1394
 806           specification which is now the standard for FireWire controllers.
 807
 808           With remote DMA, you can monitor the printk buffer remotely using
 809           firescope and access all memory below 4GB using fireproxy from gdb.
 810           Even controlling a kernel debugger is possible using remote DMA.
 811
 812           Usage:
 813
 814           If ohci1394_dma=early is used as boot parameter, it will initialize
 815           all OHCI1394 controllers which are found in the PCI config space.
 816
 817           As all changes to the FireWire bus such as enabling and disabling
 818           devices cause a bus reset and thereby disable remote DMA for all
 819           devices, be sure to have the cable plugged and FireWire enabled on
 820           the debugging host before booting the debug target for debugging.
 821
 822           This code (~1k) is freed after boot. By then, the firewire stack
 823           in charge of the OHCI-1394 controllers should be used instead.
 824
 825           See Documentation/debugging-via-ohci1394.txt for more information.
 826
 827 config FIREWIRE_OHCI_REMOTE_DMA
 828         bool "Remote debugging over FireWire with firewire-ohci"
 829         depends on FIREWIRE_OHCI
 830         help
 831           This option lets you use the FireWire bus for remote debugging
 832           with help of the firewire-ohci driver. It enables unfiltered
 833           remote DMA in firewire-ohci.
 834           See Documentation/debugging-via-ohci1394.txt for more information.
 835
 836           If unsure, say N.
 837
 838 menuconfig BUILD_DOCSRC
 839         bool "Build targets in Documentation/ tree"
 840         depends on HEADERS_CHECK
 841         help
 842           This option attempts to build objects from the source files in the
 843           kernel Documentation/ tree.
 844
 845           Say N if you are unsure.
 846
 847 config DYNAMIC_PRINTK_DEBUG
 848         bool "Enable dynamic printk() call support"
 849         default n
 850         depends on PRINTK
 851         select PRINTK_DEBUG
 852         help
 853
 854           Compiles debug level messages into the kernel, which would not
 855           otherwise be available at runtime. These messages can then be
 856           enabled/disabled on a per module basis. This mechanism implicitly
 857           enables all pr_debug() and dev_dbg() calls. The impact of this
 858           compile option is a larger kernel text size of about 2%.
 859
 860           Usage:
 861
 862           Dynamic debugging is controlled by the debugfs file,
 863           dynamic_printk/modules. This file contains a list of the modules that
 864           can be enabled. The format of the file is the module name, followed
 865           by a set of flags that can be enabled. The first flag is always the
 866           'enabled' flag. For example:
 867
 868                 <module_name> <enabled=0/1>
 869                                 .
 870                                 .
 871                                 .
 872
 873           <module_name> : Name of the module in which the debug call resides
 874           <enabled=0/1> : whether the messages are enabled or not
 875
 876           From a live system:
 877
 878                 snd_hda_intel enabled=0
 879                 fixup enabled=0
 880                 driver enabled=0
 881
 882           Enable a module:
 883
 884                 $echo "set enabled=1 <module_name>" > dynamic_printk/modules
 885
 886           Disable a module:
 887
 888                 $echo "set enabled=0 <module_name>" > dynamic_printk/modules
 889
 890           Enable all modules:
 891
 892                 $echo "set enabled=1 all" > dynamic_printk/modules
 893
 894           Disable all modules:
 895
 896                 $echo "set enabled=0 all" > dynamic_printk/modules
 897
 898           Finally, passing "dynamic_printk" at the command line enables
 899           debugging for all modules. This mode can be turned off via the above
 900           disable command.
 901
 902 source "samples/Kconfig"
 903
 904 source "lib/Kconfig.kgdb"