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 DETECT_HUNG_TASK
 190         bool "Detect Hung Tasks"
 191         depends on DEBUG_KERNEL
 192         default DETECT_SOFTLOCKUP
 193         help
 194           Say Y here to enable the kernel to detect "hung tasks",
 195           which are bugs that cause the task to be stuck in
 196           uninterruptible "D" state indefinitiley.
 197
 198           When a hung task is detected, the kernel will print the
 199           current stack trace (which you should report), but the
 200           task will stay in uninterruptible state. If lockdep is
 201           enabled then all held locks will also be reported. This
 202           feature has negligible overhead.
 203
 204 config BOOTPARAM_HUNG_TASK_PANIC
 205         bool "Panic (Reboot) On Hung Tasks"
 206         depends on DETECT_HUNG_TASK
 207         help
 208           Say Y here to enable the kernel to panic on "hung tasks",
 209           which are bugs that cause the kernel to leave a task stuck
 210           in uninterruptible "D" state.
 211
 212           The panic can be used in combination with panic_timeout,
 213           to cause the system to reboot automatically after a
 214           hung task has been detected. This feature is useful for
 215           high-availability systems that have uptime guarantees and
 216           where a hung tasks must be resolved ASAP.
 217
 218           Say N if unsure.
 219
 220 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 221         int
 222         depends on DETECT_HUNG_TASK
 223         range 0 1
 224         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 225         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 226
 227 config SCHED_DEBUG
 228         bool "Collect scheduler debugging info"
 229         depends on DEBUG_KERNEL && PROC_FS
 230         default y
 231         help
 232           If you say Y here, the /proc/sched_debug file will be provided
 233           that can help debug the scheduler. The runtime overhead of this
 234           option is minimal.
 235
 236 config SCHEDSTATS
 237         bool "Collect scheduler statistics"
 238         depends on DEBUG_KERNEL && PROC_FS
 239         help
 240           If you say Y here, additional code will be inserted into the
 241           scheduler and related routines to collect statistics about
 242           scheduler behavior and provide them in /proc/schedstat.  These
 243           stats may be useful for both tuning and debugging the scheduler
 244           If you aren't debugging the scheduler or trying to tune a specific
 245           application, you can say N to avoid the very slight overhead
 246           this adds.
 247
 248 config TIMER_STATS
 249         bool "Collect kernel timers statistics"
 250         depends on DEBUG_KERNEL && PROC_FS
 251         help
 252           If you say Y here, additional code will be inserted into the
 253           timer routines to collect statistics about kernel timers being
 254           reprogrammed. The statistics can be read from /proc/timer_stats.
 255           The statistics collection is started by writing 1 to /proc/timer_stats,
 256           writing 0 stops it. This feature is useful to collect information
 257           about timer usage patterns in kernel and userspace. This feature
 258           is lightweight if enabled in the kernel config but not activated
 259           (it defaults to deactivated on bootup and will only be activated
 260           if some application like powertop activates it explicitly).
 261
 262 config DEBUG_OBJECTS
 263         bool "Debug object operations"
 264         depends on DEBUG_KERNEL
 265         help
 266           If you say Y here, additional code will be inserted into the
 267           kernel to track the life time of various objects and validate
 268           the operations on those objects.
 269
 270 config DEBUG_OBJECTS_SELFTEST
 271         bool "Debug objects selftest"
 272         depends on DEBUG_OBJECTS
 273         help
 274           This enables the selftest of the object debug code.
 275
 276 config DEBUG_OBJECTS_FREE
 277         bool "Debug objects in freed memory"
 278         depends on DEBUG_OBJECTS
 279         help
 280           This enables checks whether a k/v free operation frees an area
 281           which contains an object which has not been deactivated
 282           properly. This can make kmalloc/kfree-intensive workloads
 283           much slower.
 284
 285 config DEBUG_OBJECTS_TIMERS
 286         bool "Debug timer objects"
 287         depends on DEBUG_OBJECTS
 288         help
 289           If you say Y here, additional code will be inserted into the
 290           timer routines to track the life time of timer objects and
 291           validate the timer operations.
 292
 293 config DEBUG_OBJECTS_ENABLE_DEFAULT
 294         int "debug_objects bootup default value (0-1)"
 295         range 0 1
 296         default "1"
 297         depends on DEBUG_OBJECTS
 298         help
 299           Debug objects boot parameter default value
 300
 301 config DEBUG_SLAB
 302         bool "Debug slab memory allocations"
 303         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 304         help
 305           Say Y here to have the kernel do limited verification on memory
 306           allocation as well as poisoning memory on free to catch use of freed
 307           memory. This can make kmalloc/kfree-intensive workloads much slower.
 308
 309 config DEBUG_SLAB_LEAK
 310         bool "Memory leak debugging"
 311         depends on DEBUG_SLAB
 312
 313 config SLUB_DEBUG_ON
 314         bool "SLUB debugging on by default"
 315         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 316         default n
 317         help
 318           Boot with debugging on by default. SLUB boots by default with
 319           the runtime debug capabilities switched off. Enabling this is
 320           equivalent to specifying the "slub_debug" parameter on boot.
 321           There is no support for more fine grained debug control like
 322           possible with slub_debug=xxx. SLUB debugging may be switched
 323           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 324           "slub_debug=-".
 325
 326 config SLUB_STATS
 327         default n
 328         bool "Enable SLUB performance statistics"
 329         depends on SLUB && SLUB_DEBUG && SYSFS
 330         help
 331           SLUB statistics are useful to debug SLUBs allocation behavior in
 332           order find ways to optimize the allocator. This should never be
 333           enabled for production use since keeping statistics slows down
 334           the allocator by a few percentage points. The slabinfo command
 335           supports the determination of the most active slabs to figure
 336           out which slabs are relevant to a particular load.
 337           Try running: slabinfo -DA
 338
 339 config DEBUG_KMEMLEAK
 340         bool "Kernel memory leak detector"
 341         depends on DEBUG_KERNEL && EXPERIMENTAL && (X86 || ARM) && \
 342                 !MEMORY_HOTPLUG
 343         select DEBUG_SLAB if SLAB
 344         select SLUB_DEBUG if SLUB
 345         select DEBUG_FS if SYSFS
 346         select STACKTRACE if STACKTRACE_SUPPORT
 347         select KALLSYMS
 348         help
 349           Say Y here if you want to enable the memory leak
 350           detector. The memory allocation/freeing is traced in a way
 351           similar to the Boehm's conservative garbage collector, the
 352           difference being that the orphan objects are not freed but
 353           only shown in /sys/kernel/debug/kmemleak. Enabling this
 354           feature will introduce an overhead to memory
 355           allocations. See Documentation/kmemleak.txt for more
 356           details.
 357
 358           In order to access the kmemleak file, debugfs needs to be
 359           mounted (usually at /sys/kernel/debug).
 360
 361 config DEBUG_KMEMLEAK_TEST
 362         tristate "Simple test for the kernel memory leak detector"
 363         depends on DEBUG_KMEMLEAK
 364         help
 365           Say Y or M here to build a test for the kernel memory leak
 366           detector. This option enables a module that explicitly leaks
 367           memory.
 368
 369           If unsure, say N.
 370
 371 config DEBUG_PREEMPT
 372         bool "Debug preemptible kernel"
 373         depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
 374         default y
 375         help
 376           If you say Y here then the kernel will use a debug variant of the
 377           commonly used smp_processor_id() function and will print warnings
 378           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 379           will detect preemption count underflows.
 380
 381 config DEBUG_RT_MUTEXES
 382         bool "RT Mutex debugging, deadlock detection"
 383         depends on DEBUG_KERNEL && RT_MUTEXES
 384         help
 385          This allows rt mutex semantics violations and rt mutex related
 386          deadlocks (lockups) to be detected and reported automatically.
 387
 388 config DEBUG_PI_LIST
 389         bool
 390         default y
 391         depends on DEBUG_RT_MUTEXES
 392
 393 config RT_MUTEX_TESTER
 394         bool "Built-in scriptable tester for rt-mutexes"
 395         depends on DEBUG_KERNEL && RT_MUTEXES
 396         help
 397           This option enables a rt-mutex tester.
 398
 399 config DEBUG_SPINLOCK
 400         bool "Spinlock and rw-lock debugging: basic checks"
 401         depends on DEBUG_KERNEL
 402         help
 403           Say Y here and build SMP to catch missing spinlock initialization
 404           and certain other kinds of spinlock errors commonly made.  This is
 405           best used in conjunction with the NMI watchdog so that spinlock
 406           deadlocks are also debuggable.
 407
 408 config DEBUG_MUTEXES
 409         bool "Mutex debugging: basic checks"
 410         depends on DEBUG_KERNEL
 411         help
 412          This feature allows mutex semantics violations to be detected and
 413          reported.
 414
 415 config DEBUG_LOCK_ALLOC
 416         bool "Lock debugging: detect incorrect freeing of live locks"
 417         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 418         select DEBUG_SPINLOCK
 419         select DEBUG_MUTEXES
 420         select LOCKDEP
 421         help
 422          This feature will check whether any held lock (spinlock, rwlock,
 423          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 424          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 425          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 426          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 427          held during task exit.
 428
 429 config PROVE_LOCKING
 430         bool "Lock debugging: prove locking correctness"
 431         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 432         select LOCKDEP
 433         select DEBUG_SPINLOCK
 434         select DEBUG_MUTEXES
 435         select DEBUG_LOCK_ALLOC
 436         default n
 437         help
 438          This feature enables the kernel to prove that all locking
 439          that occurs in the kernel runtime is mathematically
 440          correct: that under no circumstance could an arbitrary (and
 441          not yet triggered) combination of observed locking
 442          sequences (on an arbitrary number of CPUs, running an
 443          arbitrary number of tasks and interrupt contexts) cause a
 444          deadlock.
 445
 446          In short, this feature enables the kernel to report locking
 447          related deadlocks before they actually occur.
 448
 449          The proof does not depend on how hard and complex a
 450          deadlock scenario would be to trigger: how many
 451          participant CPUs, tasks and irq-contexts would be needed
 452          for it to trigger. The proof also does not depend on
 453          timing: if a race and a resulting deadlock is possible
 454          theoretically (no matter how unlikely the race scenario
 455          is), it will be proven so and will immediately be
 456          reported by the kernel (once the event is observed that
 457          makes the deadlock theoretically possible).
 458
 459          If a deadlock is impossible (i.e. the locking rules, as
 460          observed by the kernel, are mathematically correct), the
 461          kernel reports nothing.
 462
 463          NOTE: this feature can also be enabled for rwlocks, mutexes
 464          and rwsems - in which case all dependencies between these
 465          different locking variants are observed and mapped too, and
 466          the proof of observed correctness is also maintained for an
 467          arbitrary combination of these separate locking variants.
 468
 469          For more details, see Documentation/lockdep-design.txt.
 470
 471 config LOCKDEP
 472         bool
 473         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 474         select STACKTRACE
 475         select FRAME_POINTER if !X86 && !MIPS && !PPC && !ARM_UNWIND && !S390
 476         select KALLSYMS
 477         select KALLSYMS_ALL
 478
 479 config LOCK_STAT
 480         bool "Lock usage statistics"
 481         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 482         select LOCKDEP
 483         select DEBUG_SPINLOCK
 484         select DEBUG_MUTEXES
 485         select DEBUG_LOCK_ALLOC
 486         default n
 487         help
 488          This feature enables tracking lock contention points
 489
 490          For more details, see Documentation/lockstat.txt
 491
 492 config DEBUG_LOCKDEP
 493         bool "Lock dependency engine debugging"
 494         depends on DEBUG_KERNEL && LOCKDEP
 495         help
 496           If you say Y here, the lock dependency engine will do
 497           additional runtime checks to debug itself, at the price
 498           of more runtime overhead.
 499
 500 config TRACE_IRQFLAGS
 501         depends on DEBUG_KERNEL
 502         bool
 503         default y
 504         depends on TRACE_IRQFLAGS_SUPPORT
 505         depends on PROVE_LOCKING
 506
 507 config DEBUG_SPINLOCK_SLEEP
 508         bool "Spinlock debugging: sleep-inside-spinlock checking"
 509         depends on DEBUG_KERNEL
 510         help
 511           If you say Y here, various routines which may sleep will become very
 512           noisy if they are called with a spinlock held.
 513
 514 config DEBUG_LOCKING_API_SELFTESTS
 515         bool "Locking API boot-time self-tests"
 516         depends on DEBUG_KERNEL
 517         help
 518           Say Y here if you want the kernel to run a short self-test during
 519           bootup. The self-test checks whether common types of locking bugs
 520           are detected by debugging mechanisms or not. (if you disable
 521           lock debugging then those bugs wont be detected of course.)
 522           The following locking APIs are covered: spinlocks, rwlocks,
 523           mutexes and rwsems.
 524
 525 config STACKTRACE
 526         bool
 527         depends on STACKTRACE_SUPPORT
 528
 529 config DEBUG_KOBJECT
 530         bool "kobject debugging"
 531         depends on DEBUG_KERNEL
 532         help
 533           If you say Y here, some extra kobject debugging messages will be sent
 534           to the syslog.
 535
 536 config DEBUG_HIGHMEM
 537         bool "Highmem debugging"
 538         depends on DEBUG_KERNEL && HIGHMEM
 539         help
 540           This options enables addition error checking for high memory systems.
 541           Disable for production systems.
 542
 543 config DEBUG_BUGVERBOSE
 544         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 545         depends on BUG
 546         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 547                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 548         default !EMBEDDED
 549         help
 550           Say Y here to make BUG() panics output the file name and line number
 551           of the BUG call as well as the EIP and oops trace.  This aids
 552           debugging but costs about 70-100K of memory.
 553
 554 config DEBUG_INFO
 555         bool "Compile the kernel with debug info"
 556         depends on DEBUG_KERNEL
 557         help
 558           If you say Y here the resulting kernel image will include
 559           debugging info resulting in a larger kernel image.
 560           This adds debug symbols to the kernel and modules (gcc -g), and
 561           is needed if you intend to use kernel crashdump or binary object
 562           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 563           Say Y here only if you plan to debug the kernel.
 564
 565           If unsure, say N.
 566
 567 config DEBUG_VM
 568         bool "Debug VM"
 569         depends on DEBUG_KERNEL
 570         help
 571           Enable this to turn on extended checks in the virtual-memory system
 572           that may impact performance.
 573
 574           If unsure, say N.
 575
 576 config DEBUG_VIRTUAL
 577         bool "Debug VM translations"
 578         depends on DEBUG_KERNEL && X86
 579         help
 580           Enable some costly sanity checks in virtual to page code. This can
 581           catch mistakes with virt_to_page() and friends.
 582
 583           If unsure, say N.
 584
 585 config DEBUG_NOMMU_REGIONS
 586         bool "Debug the global anon/private NOMMU mapping region tree"
 587         depends on DEBUG_KERNEL && !MMU
 588         help
 589           This option causes the global tree of anonymous and private mapping
 590           regions to be regularly checked for invalid topology.
 591
 592 config DEBUG_WRITECOUNT
 593         bool "Debug filesystem writers count"
 594         depends on DEBUG_KERNEL
 595         help
 596           Enable this to catch wrong use of the writers count in struct
 597           vfsmount.  This will increase the size of each file struct by
 598           32 bits.
 599
 600           If unsure, say N.
 601
 602 config DEBUG_MEMORY_INIT
 603         bool "Debug memory initialisation" if EMBEDDED
 604         default !EMBEDDED
 605         help
 606           Enable this for additional checks during memory initialisation.
 607           The sanity checks verify aspects of the VM such as the memory model
 608           and other information provided by the architecture. Verbose
 609           information will be printed at KERN_DEBUG loglevel depending
 610           on the mminit_loglevel= command-line option.
 611
 612           If unsure, say Y
 613
 614 config DEBUG_LIST
 615         bool "Debug linked list manipulation"
 616         depends on DEBUG_KERNEL
 617         help
 618           Enable this to turn on extended checks in the linked-list
 619           walking routines.
 620
 621           If unsure, say N.
 622
 623 config DEBUG_SG
 624         bool "Debug SG table operations"
 625         depends on DEBUG_KERNEL
 626         help
 627           Enable this to turn on checks on scatter-gather tables. This can
 628           help find problems with drivers that do not properly initialize
 629           their sg tables.
 630
 631           If unsure, say N.
 632
 633 config DEBUG_NOTIFIERS
 634         bool "Debug notifier call chains"
 635         depends on DEBUG_KERNEL
 636         help
 637           Enable this to turn on sanity checking for notifier call chains.
 638           This is most useful for kernel developers to make sure that
 639           modules properly unregister themselves from notifier chains.
 640           This is a relatively cheap check but if you care about maximum
 641           performance, say N.
 642
 643 #
 644 # Select this config option from the architecture Kconfig, if it
 645 # it is preferred to always offer frame pointers as a config
 646 # option on the architecture (regardless of KERNEL_DEBUG):
 647 #
 648 config ARCH_WANT_FRAME_POINTERS
 649         bool
 650         help
 651
 652 config FRAME_POINTER
 653         bool "Compile the kernel with frame pointers"
 654         depends on DEBUG_KERNEL && \
 655                 (CRIS || M68K || M68KNOMMU || FRV || UML || \
 656                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 657                 ARCH_WANT_FRAME_POINTERS
 658         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 659         help
 660           If you say Y here the resulting kernel image will be slightly
 661           larger and slower, but it gives very useful debugging information
 662           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 663
 664 config BOOT_PRINTK_DELAY
 665         bool "Delay each boot printk message by N milliseconds"
 666         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 667         help
 668           This build option allows you to read kernel boot messages
 669           by inserting a short delay after each one.  The delay is
 670           specified in milliseconds on the kernel command line,
 671           using "boot_delay=N".
 672
 673           It is likely that you would also need to use "lpj=M" to preset
 674           the "loops per jiffie" value.
 675           See a previous boot log for the "lpj" value to use for your
 676           system, and then set "lpj=M" before setting "boot_delay=N".
 677           NOTE:  Using this option may adversely affect SMP systems.
 678           I.e., processors other than the first one may not boot up.
 679           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 680           what it believes to be lockup conditions.
 681
 682 config RCU_TORTURE_TEST
 683         tristate "torture tests for RCU"
 684         depends on DEBUG_KERNEL
 685         default n
 686         help
 687           This option provides a kernel module that runs torture tests
 688           on the RCU infrastructure.  The kernel module may be built
 689           after the fact on the running kernel to be tested, if desired.
 690
 691           Say Y here if you want RCU torture tests to be built into
 692           the kernel.
 693           Say M if you want the RCU torture tests to build as a module.
 694           Say N if you are unsure.
 695
 696 config RCU_TORTURE_TEST_RUNNABLE
 697         bool "torture tests for RCU runnable by default"
 698         depends on RCU_TORTURE_TEST = y
 699         default n
 700         help
 701           This option provides a way to build the RCU torture tests
 702           directly into the kernel without them starting up at boot
 703           time.  You can use /proc/sys/kernel/rcutorture_runnable
 704           to manually override this setting.  This /proc file is
 705           available only when the RCU torture tests have been built
 706           into the kernel.
 707
 708           Say Y here if you want the RCU torture tests to start during
 709           boot (you probably don't).
 710           Say N here if you want the RCU torture tests to start only
 711           after being manually enabled via /proc.
 712
 713 config RCU_CPU_STALL_DETECTOR
 714         bool "Check for stalled CPUs delaying RCU grace periods"
 715         depends on CLASSIC_RCU || TREE_RCU
 716         default n
 717         help
 718           This option causes RCU to printk information on which
 719           CPUs are delaying the current grace period, but only when
 720           the grace period extends for excessive time periods.
 721
 722           Say Y if you want RCU to perform such checks.
 723
 724           Say N if you are unsure.
 725
 726 config KPROBES_SANITY_TEST
 727         bool "Kprobes sanity tests"
 728         depends on DEBUG_KERNEL
 729         depends on KPROBES
 730         default n
 731         help
 732           This option provides for testing basic kprobes functionality on
 733           boot. A sample kprobe, jprobe and kretprobe are inserted and
 734           verified for functionality.
 735
 736           Say N if you are unsure.
 737
 738 config BACKTRACE_SELF_TEST
 739         tristate "Self test for the backtrace code"
 740         depends on DEBUG_KERNEL
 741         default n
 742         help
 743           This option provides a kernel module that can be used to test
 744           the kernel stack backtrace code. This option is not useful
 745           for distributions or general kernels, but only for kernel
 746           developers working on architecture code.
 747
 748           Note that if you want to also test saved backtraces, you will
 749           have to enable STACKTRACE as well.
 750
 751           Say N if you are unsure.
 752
 753 config DEBUG_BLOCK_EXT_DEVT
 754         bool "Force extended block device numbers and spread them"
 755         depends on DEBUG_KERNEL
 756         depends on BLOCK
 757         default n
 758         help
 759           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 760           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 761           YOU ARE DOING.  Distros, please enable this and fix whatever
 762           is broken.
 763
 764           Conventionally, block device numbers are allocated from
 765           predetermined contiguous area.  However, extended block area
 766           may introduce non-contiguous block device numbers.  This
 767           option forces most block device numbers to be allocated from
 768           the extended space and spreads them to discover kernel or
 769           userland code paths which assume predetermined contiguous
 770           device number allocation.
 771
 772           Note that turning on this debug option shuffles all the
 773           device numbers for all IDE and SCSI devices including libata
 774           ones, so root partition specified using device number
 775           directly (via rdev or root=MAJ:MIN) won't work anymore.
 776           Textual device names (root=/dev/sdXn) will continue to work.
 777
 778           Say N if you are unsure.
 779
 780 config LKDTM
 781         tristate "Linux Kernel Dump Test Tool Module"
 782         depends on DEBUG_KERNEL
 783         depends on KPROBES
 784         depends on BLOCK
 785         default n
 786         help
 787         This module enables testing of the different dumping mechanisms by
 788         inducing system failures at predefined crash points.
 789         If you don't need it: say N
 790         Choose M here to compile this code as a module. The module will be
 791         called lkdtm.
 792
 793         Documentation on how to use the module can be found in
 794         drivers/misc/lkdtm.c
 795
 796 config FAULT_INJECTION
 797         bool "Fault-injection framework"
 798         depends on DEBUG_KERNEL
 799         help
 800           Provide fault-injection framework.
 801           For more details, see Documentation/fault-injection/.
 802
 803 config FAILSLAB
 804         bool "Fault-injection capability for kmalloc"
 805         depends on FAULT_INJECTION
 806         depends on SLAB || SLUB
 807         help
 808           Provide fault-injection capability for kmalloc.
 809
 810 config FAIL_PAGE_ALLOC
 811         bool "Fault-injection capabilitiy for alloc_pages()"
 812         depends on FAULT_INJECTION
 813         help
 814           Provide fault-injection capability for alloc_pages().
 815
 816 config FAIL_MAKE_REQUEST
 817         bool "Fault-injection capability for disk IO"
 818         depends on FAULT_INJECTION && BLOCK
 819         help
 820           Provide fault-injection capability for disk IO.
 821
 822 config FAIL_IO_TIMEOUT
 823         bool "Faul-injection capability for faking disk interrupts"
 824         depends on FAULT_INJECTION && BLOCK
 825         help
 826           Provide fault-injection capability on end IO handling. This
 827           will make the block layer "forget" an interrupt as configured,
 828           thus exercising the error handling.
 829
 830           Only works with drivers that use the generic timeout handling,
 831           for others it wont do anything.
 832
 833 config FAULT_INJECTION_DEBUG_FS
 834         bool "Debugfs entries for fault-injection capabilities"
 835         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 836         help
 837           Enable configuration of fault-injection capabilities via debugfs.
 838
 839 config FAULT_INJECTION_STACKTRACE_FILTER
 840         bool "stacktrace filter for fault-injection capabilities"
 841         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 842         depends on !X86_64
 843         select STACKTRACE
 844         select FRAME_POINTER if !PPC && !S390
 845         help
 846           Provide stacktrace filter for fault-injection capabilities
 847
 848 config LATENCYTOP
 849         bool "Latency measuring infrastructure"
 850         select FRAME_POINTER if !MIPS && !PPC && !S390
 851         select KALLSYMS
 852         select KALLSYMS_ALL
 853         select STACKTRACE
 854         select SCHEDSTATS
 855         select SCHED_DEBUG
 856         depends on HAVE_LATENCYTOP_SUPPORT
 857         help
 858           Enable this option if you want to use the LatencyTOP tool
 859           to find out which userspace is blocking on what kernel operations.
 860
 861 config SYSCTL_SYSCALL_CHECK
 862         bool "Sysctl checks"
 863         depends on SYSCTL_SYSCALL
 864         ---help---
 865           sys_sysctl uses binary paths that have been found challenging
 866           to properly maintain and use. This enables checks that help
 867           you to keep things correct.
 868
 869 source mm/Kconfig.debug
 870 source kernel/trace/Kconfig
 871
 872 config PROVIDE_OHCI1394_DMA_INIT
 873         bool "Remote debugging over FireWire early on boot"
 874         depends on PCI && X86
 875         help
 876           If you want to debug problems which hang or crash the kernel early
 877           on boot and the crashing machine has a FireWire port, you can use
 878           this feature to remotely access the memory of the crashed machine
 879           over FireWire. This employs remote DMA as part of the OHCI1394
 880           specification which is now the standard for FireWire controllers.
 881
 882           With remote DMA, you can monitor the printk buffer remotely using
 883           firescope and access all memory below 4GB using fireproxy from gdb.
 884           Even controlling a kernel debugger is possible using remote DMA.
 885
 886           Usage:
 887
 888           If ohci1394_dma=early is used as boot parameter, it will initialize
 889           all OHCI1394 controllers which are found in the PCI config space.
 890
 891           As all changes to the FireWire bus such as enabling and disabling
 892           devices cause a bus reset and thereby disable remote DMA for all
 893           devices, be sure to have the cable plugged and FireWire enabled on
 894           the debugging host before booting the debug target for debugging.
 895
 896           This code (~1k) is freed after boot. By then, the firewire stack
 897           in charge of the OHCI-1394 controllers should be used instead.
 898
 899           See Documentation/debugging-via-ohci1394.txt for more information.
 900
 901 config FIREWIRE_OHCI_REMOTE_DMA
 902         bool "Remote debugging over FireWire with firewire-ohci"
 903         depends on FIREWIRE_OHCI
 904         help
 905           This option lets you use the FireWire bus for remote debugging
 906           with help of the firewire-ohci driver. It enables unfiltered
 907           remote DMA in firewire-ohci.
 908           See Documentation/debugging-via-ohci1394.txt for more information.
 909
 910           If unsure, say N.
 911
 912 config BUILD_DOCSRC
 913         bool "Build targets in Documentation/ tree"
 914         depends on HEADERS_CHECK
 915         help
 916           This option attempts to build objects from the source files in the
 917           kernel Documentation/ tree.
 918
 919           Say N if you are unsure.
 920
 921 config DYNAMIC_DEBUG
 922         bool "Enable dynamic printk() support"
 923         default n
 924         depends on PRINTK
 925         depends on DEBUG_FS
 926         help
 927
 928           Compiles debug level messages into the kernel, which would not
 929           otherwise be available at runtime. These messages can then be
 930           enabled/disabled based on various levels of scope - per source file,
 931           function, module, format string, and line number. This mechanism
 932           implicitly enables all pr_debug() and dev_dbg() calls. The impact of
 933           this compile option is a larger kernel text size of about 2%.
 934
 935           Usage:
 936
 937           Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
 938           which is contained in the 'debugfs' filesystem. Thus, the debugfs
 939           filesystem must first be mounted before making use of this feature.
 940           We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
 941           file contains a list of the debug statements that can be enabled. The
 942           format for each line of the file is:
 943
 944                 filename:lineno [module]function flags format
 945
 946           filename : source file of the debug statement
 947           lineno : line number of the debug statement
 948           module : module that contains the debug statement
 949           function : function that contains the debug statement
 950           flags : 'p' means the line is turned 'on' for printing
 951           format : the format used for the debug statement
 952
 953           From a live system:
 954
 955                 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
 956                 # filename:lineno [module]function flags format
 957                 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
 958                 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
 959                 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
 960
 961           Example usage:
 962
 963                 // enable the message at line 1603 of file svcsock.c
 964                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
 965                                                 <debugfs>/dynamic_debug/ddebug
 966
 967                 // enable all the messages in file svcsock.c
 968                 nullarbor:~ # echo -n 'file svcsock.c +p' >
 969                                                 <debugfs>/dynamic_debug/ddebug
 970
 971                 // enable all the messages in the NFS server module
 972                 nullarbor:~ # echo -n 'module nfsd +p' >
 973                                                 <debugfs>/dynamic_debug/ddebug
 974
 975                 // enable all 12 messages in the function svc_process()
 976                 nullarbor:~ # echo -n 'func svc_process +p' >
 977                                                 <debugfs>/dynamic_debug/ddebug
 978
 979                 // disable all 12 messages in the function svc_process()
 980                 nullarbor:~ # echo -n 'func svc_process -p' >
 981                                                 <debugfs>/dynamic_debug/ddebug
 982
 983           See Documentation/dynamic-debug-howto.txt for additional information.
 984
 985 config DMA_API_DEBUG
 986         bool "Enable debugging of DMA-API usage"
 987         depends on HAVE_DMA_API_DEBUG
 988         help
 989           Enable this option to debug the use of the DMA API by device drivers.
 990           With this option you will be able to detect common bugs in device
 991           drivers like double-freeing of DMA mappings or freeing mappings that
 992           were never allocated.
 993           This option causes a performance degredation.  Use only if you want
 994           to debug device drivers. If unsure, say N.
 995
 996 source "samples/Kconfig"
 997
 998 source "lib/Kconfig.kgdb"