lib/Kconfig.debug

   1
   2 config PRINTK_TIME
   3         bool "Show timing information on printks"
   4         depends on PRINTK
   5         help
   6           Selecting this option causes timing information to be
   7           included in printk output.  This allows you to measure
   8           the interval between kernel operations, including bootup
   9           operations.  This is useful for identifying long delays
  10           in kernel startup.
  11
  12 config ENABLE_WARN_DEPRECATED
  13         bool "Enable __deprecated logic"
  14         default y
  15         help
  16           Enable the __deprecated logic in the kernel build.
  17           Disable this to suppress the "warning: 'foo' is deprecated
  18           (declared at kernel/power/somefile.c:1234)" messages.
  19
  20 config ENABLE_MUST_CHECK
  21         bool "Enable __must_check logic"
  22         default y
  23         help
  24           Enable the __must_check logic in the kernel build.  Disable this to
  25           suppress the "warning: ignoring return value of 'foo', declared with
  26           attribute warn_unused_result" messages.
  27
  28 config FRAME_WARN
  29         int "Warn for stack frames larger than (needs gcc 4.4)"
  30         range 0 8192
  31         default 1024 if !64BIT
  32         default 2048 if 64BIT
  33         help
  34           Tell gcc to warn at build time for stack frames larger than this.
  35           Setting this too low will cause a lot of warnings.
  36           Setting it to 0 disables the warning.
  37           Requires gcc 4.4
  38
  39 config MAGIC_SYSRQ
  40         bool "Magic SysRq key"
  41         depends on !UML
  42         help
  43           If you say Y here, you will have some control over the system even
  44           if the system crashes for example during kernel debugging (e.g., you
  45           will be able to flush the buffer cache to disk, reboot the system
  46           immediately or dump some status information). This is accomplished
  47           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  48           also works on a serial console (on PC hardware at least), if you
  49           send a BREAK and then within 5 seconds a command keypress. The
  50           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  51           unless you really know what this hack does.
  52
  53 config STRIP_ASM_SYMS
  54         bool "Strip assembler-generated symbols during link"
  55         default n
  56         help
  57           Strip internal assembler-generated symbols during a link (symbols
  58           that look like '.Lxxx') so they don't pollute the output of
  59           get_wchan() and suchlike.
  60
  61 config UNUSED_SYMBOLS
  62         bool "Enable unused/obsolete exported symbols"
  63         default y if X86
  64         help
  65           Unused but exported symbols make the kernel needlessly bigger.  For
  66           that reason most of these unused exports will soon be removed.  This
  67           option is provided temporarily to provide a transition period in case
  68           some external kernel module needs one of these symbols anyway. If you
  69           encounter such a case in your module, consider if you are actually
  70           using the right API.  (rationale: since nobody in the kernel is using
  71           this in a module, there is a pretty good chance it's actually the
  72           wrong interface to use).  If you really need the symbol, please send a
  73           mail to the linux kernel mailing list mentioning the symbol and why
  74           you really need it, and what the merge plan to the mainline kernel for
  75           your module is.
  76
  77 config DEBUG_FS
  78         bool "Debug Filesystem"
  79         depends on SYSFS
  80         help
  81           debugfs is a virtual file system that kernel developers use to put
  82           debugging files into.  Enable this option to be able to read and
  83           write to these files.
  84
  85           For detailed documentation on the debugfs API, see
  86           Documentation/DocBook/filesystems.
  87
  88           If unsure, say N.
  89
  90 config HEADERS_CHECK
  91         bool "Run 'make headers_check' when building vmlinux"
  92         depends on !UML
  93         help
  94           This option will extract the user-visible kernel headers whenever
  95           building the kernel, and will run basic sanity checks on them to
  96           ensure that exported files do not attempt to include files which
  97           were not exported, etc.
  98
  99           If you're making modifications to header files which are
 100           relevant for userspace, say 'Y', and check the headers
 101           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 102           your build tree), to make sure they're suitable.
 103
 104 config DEBUG_SECTION_MISMATCH
 105         bool "Enable full Section mismatch analysis"
 106         depends on UNDEFINED
 107         # This option is on purpose disabled for now.
 108         # It will be enabled when we are down to a reasonable number
 109         # of section mismatch warnings (< 10 for an allyesconfig build)
 110         help
 111           The section mismatch analysis checks if there are illegal
 112           references from one section to another section.
 113           Linux will during link or during runtime drop some sections
 114           and any use of code/data previously in these sections will
 115           most likely result in an oops.
 116           In the code functions and variables are annotated with
 117           __init, __devinit etc. (see full list in include/linux/init.h)
 118           which results in the code/data being placed in specific sections.
 119           The section mismatch analysis is always done after a full
 120           kernel build but enabling this option will in addition
 121           do the following:
 122           - Add the option -fno-inline-functions-called-once to gcc
 123             When inlining a function annotated __init in a non-init
 124             function we would lose the section information and thus
 125             the analysis would not catch the illegal reference.
 126             This option tells gcc to inline less but will also
 127             result in a larger kernel.
 128           - Run the section mismatch analysis for each module/built-in.o
 129             When we run the section mismatch analysis on vmlinux.o we
 130             lose valueble information about where the mismatch was
 131             introduced.
 132             Running the analysis for each module/built-in.o file
 133             will tell where the mismatch happens much closer to the
 134             source. The drawback is that we will report the same
 135             mismatch at least twice.
 136           - Enable verbose reporting from modpost to help solving
 137             the section mismatches reported.
 138
 139 config DEBUG_KERNEL
 140         bool "Kernel debugging"
 141         help
 142           Say Y here if you are developing drivers or trying to debug and
 143           identify kernel problems.
 144
 145 config DEBUG_SHIRQ
 146         bool "Debug shared IRQ handlers"
 147         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 148         help
 149           Enable this to generate a spurious interrupt as soon as a shared
 150           interrupt handler is registered, and just before one is deregistered.
 151           Drivers ought to be able to handle interrupts coming in at those
 152           points; some don't and need to be caught.
 153
 154 config DETECT_SOFTLOCKUP
 155         bool "Detect Soft Lockups"
 156         depends on DEBUG_KERNEL && !S390
 157         default y
 158         help
 159           Say Y here to enable the kernel to detect "soft lockups",
 160           which are bugs that cause the kernel to loop in kernel
 161           mode for more than 60 seconds, without giving other tasks a
 162           chance to run.
 163
 164           When a soft-lockup is detected, the kernel will print the
 165           current stack trace (which you should report), but the
 166           system will stay locked up. This feature has negligible
 167           overhead.
 168
 169           (Note that "hard lockups" are separate type of bugs that
 170            can be detected via the NMI-watchdog, on platforms that
 171            support it.)
 172
 173 config BOOTPARAM_SOFTLOCKUP_PANIC
 174         bool "Panic (Reboot) On Soft Lockups"
 175         depends on DETECT_SOFTLOCKUP
 176         help
 177           Say Y here to enable the kernel to panic on "soft lockups",
 178           which are bugs that cause the kernel to loop in kernel
 179           mode for more than 60 seconds, without giving other tasks a
 180           chance to run.
 181
 182           The panic can be used in combination with panic_timeout,
 183           to cause the system to reboot automatically after a
 184           lockup has been detected. This feature is useful for
 185           high-availability systems that have uptime guarantees and
 186           where a lockup must be resolved ASAP.
 187
 188           Say N if unsure.
 189
 190 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 191         int
 192         depends on DETECT_SOFTLOCKUP
 193         range 0 1
 194         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 195         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 196
 197 config DETECT_HUNG_TASK
 198         bool "Detect Hung Tasks"
 199         depends on DEBUG_KERNEL
 200         default DETECT_SOFTLOCKUP
 201         help
 202           Say Y here to enable the kernel to detect "hung tasks",
 203           which are bugs that cause the task to be stuck in
 204           uninterruptible "D" state indefinitiley.
 205
 206           When a hung task is detected, the kernel will print the
 207           current stack trace (which you should report), but the
 208           task will stay in uninterruptible state. If lockdep is
 209           enabled then all held locks will also be reported. This
 210           feature has negligible overhead.
 211
 212 config BOOTPARAM_HUNG_TASK_PANIC
 213         bool "Panic (Reboot) On Hung Tasks"
 214         depends on DETECT_HUNG_TASK
 215         help
 216           Say Y here to enable the kernel to panic on "hung tasks",
 217           which are bugs that cause the kernel to leave a task stuck
 218           in uninterruptible "D" state.
 219
 220           The panic can be used in combination with panic_timeout,
 221           to cause the system to reboot automatically after a
 222           hung task has been detected. This feature is useful for
 223           high-availability systems that have uptime guarantees and
 224           where a hung tasks must be resolved ASAP.
 225
 226           Say N if unsure.
 227
 228 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 229         int
 230         depends on DETECT_HUNG_TASK
 231         range 0 1
 232         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 233         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 234
 235 config SCHED_DEBUG
 236         bool "Collect scheduler debugging info"
 237         depends on DEBUG_KERNEL && PROC_FS
 238         default y
 239         help
 240           If you say Y here, the /proc/sched_debug file will be provided
 241           that can help debug the scheduler. The runtime overhead of this
 242           option is minimal.
 243
 244 config SCHEDSTATS
 245         bool "Collect scheduler statistics"
 246         depends on DEBUG_KERNEL && PROC_FS
 247         help
 248           If you say Y here, additional code will be inserted into the
 249           scheduler and related routines to collect statistics about
 250           scheduler behavior and provide them in /proc/schedstat.  These
 251           stats may be useful for both tuning and debugging the scheduler
 252           If you aren't debugging the scheduler or trying to tune a specific
 253           application, you can say N to avoid the very slight overhead
 254           this adds.
 255
 256 config TIMER_STATS
 257         bool "Collect kernel timers statistics"
 258         depends on DEBUG_KERNEL && PROC_FS
 259         help
 260           If you say Y here, additional code will be inserted into the
 261           timer routines to collect statistics about kernel timers being
 262           reprogrammed. The statistics can be read from /proc/timer_stats.
 263           The statistics collection is started by writing 1 to /proc/timer_stats,
 264           writing 0 stops it. This feature is useful to collect information
 265           about timer usage patterns in kernel and userspace. This feature
 266           is lightweight if enabled in the kernel config but not activated
 267           (it defaults to deactivated on bootup and will only be activated
 268           if some application like powertop activates it explicitly).
 269
 270 config DEBUG_OBJECTS
 271         bool "Debug object operations"
 272         depends on DEBUG_KERNEL
 273         help
 274           If you say Y here, additional code will be inserted into the
 275           kernel to track the life time of various objects and validate
 276           the operations on those objects.
 277
 278 config DEBUG_OBJECTS_SELFTEST
 279         bool "Debug objects selftest"
 280         depends on DEBUG_OBJECTS
 281         help
 282           This enables the selftest of the object debug code.
 283
 284 config DEBUG_OBJECTS_FREE
 285         bool "Debug objects in freed memory"
 286         depends on DEBUG_OBJECTS
 287         help
 288           This enables checks whether a k/v free operation frees an area
 289           which contains an object which has not been deactivated
 290           properly. This can make kmalloc/kfree-intensive workloads
 291           much slower.
 292
 293 config DEBUG_OBJECTS_TIMERS
 294         bool "Debug timer objects"
 295         depends on DEBUG_OBJECTS
 296         help
 297           If you say Y here, additional code will be inserted into the
 298           timer routines to track the life time of timer objects and
 299           validate the timer operations.
 300
 301 config DEBUG_OBJECTS_ENABLE_DEFAULT
 302         int "debug_objects bootup default value (0-1)"
 303         range 0 1
 304         default "1"
 305         depends on DEBUG_OBJECTS
 306         help
 307           Debug objects boot parameter default value
 308
 309 config DEBUG_SLAB
 310         bool "Debug slab memory allocations"
 311         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 312         help
 313           Say Y here to have the kernel do limited verification on memory
 314           allocation as well as poisoning memory on free to catch use of freed
 315           memory. This can make kmalloc/kfree-intensive workloads much slower.
 316
 317 config DEBUG_SLAB_LEAK
 318         bool "Memory leak debugging"
 319         depends on DEBUG_SLAB
 320
 321 config SLUB_DEBUG_ON
 322         bool "SLUB debugging on by default"
 323         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 324         default n
 325         help
 326           Boot with debugging on by default. SLUB boots by default with
 327           the runtime debug capabilities switched off. Enabling this is
 328           equivalent to specifying the "slub_debug" parameter on boot.
 329           There is no support for more fine grained debug control like
 330           possible with slub_debug=xxx. SLUB debugging may be switched
 331           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 332           "slub_debug=-".
 333
 334 config SLUB_STATS
 335         default n
 336         bool "Enable SLUB performance statistics"
 337         depends on SLUB && SLUB_DEBUG && SYSFS
 338         help
 339           SLUB statistics are useful to debug SLUBs allocation behavior in
 340           order find ways to optimize the allocator. This should never be
 341           enabled for production use since keeping statistics slows down
 342           the allocator by a few percentage points. The slabinfo command
 343           supports the determination of the most active slabs to figure
 344           out which slabs are relevant to a particular load.
 345           Try running: slabinfo -DA
 346
 347 config DEBUG_KMEMLEAK
 348         bool "Kernel memory leak detector"
 349         depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
 350                 (X86 || ARM || PPC || S390)
 351
 352         select DEBUG_FS if SYSFS
 353         select STACKTRACE if STACKTRACE_SUPPORT
 354         select KALLSYMS
 355         help
 356           Say Y here if you want to enable the memory leak
 357           detector. The memory allocation/freeing is traced in a way
 358           similar to the Boehm's conservative garbage collector, the
 359           difference being that the orphan objects are not freed but
 360           only shown in /sys/kernel/debug/kmemleak. Enabling this
 361           feature will introduce an overhead to memory
 362           allocations. See Documentation/kmemleak.txt for more
 363           details.
 364
 365           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 366           of finding leaks due to the slab objects poisoning.
 367
 368           In order to access the kmemleak file, debugfs needs to be
 369           mounted (usually at /sys/kernel/debug).
 370
 371 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 372         int "Maximum kmemleak early log entries"
 373         depends on DEBUG_KMEMLEAK
 374         range 200 40000
 375         default 400
 376         help
 377           Kmemleak must track all the memory allocations to avoid
 378           reporting false positives. Since memory may be allocated or
 379           freed before kmemleak is initialised, an early log buffer is
 380           used to store these actions. If kmemleak reports "early log
 381           buffer exceeded", please increase this value.
 382
 383 config DEBUG_KMEMLEAK_TEST
 384         tristate "Simple test for the kernel memory leak detector"
 385         depends on DEBUG_KMEMLEAK
 386         help
 387           Say Y or M here to build a test for the kernel memory leak
 388           detector. This option enables a module that explicitly leaks
 389           memory.
 390
 391           If unsure, say N.
 392
 393 config DEBUG_PREEMPT
 394         bool "Debug preemptible kernel"
 395         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 396         default y
 397         help
 398           If you say Y here then the kernel will use a debug variant of the
 399           commonly used smp_processor_id() function and will print warnings
 400           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 401           will detect preemption count underflows.
 402
 403 config DEBUG_RT_MUTEXES
 404         bool "RT Mutex debugging, deadlock detection"
 405         depends on DEBUG_KERNEL && RT_MUTEXES
 406         help
 407          This allows rt mutex semantics violations and rt mutex related
 408          deadlocks (lockups) to be detected and reported automatically.
 409
 410 config DEBUG_PI_LIST
 411         bool
 412         default y
 413         depends on DEBUG_RT_MUTEXES
 414
 415 config RT_MUTEX_TESTER
 416         bool "Built-in scriptable tester for rt-mutexes"
 417         depends on DEBUG_KERNEL && RT_MUTEXES
 418         help
 419           This option enables a rt-mutex tester.
 420
 421 config DEBUG_SPINLOCK
 422         bool "Spinlock and rw-lock debugging: basic checks"
 423         depends on DEBUG_KERNEL
 424         help
 425           Say Y here and build SMP to catch missing spinlock initialization
 426           and certain other kinds of spinlock errors commonly made.  This is
 427           best used in conjunction with the NMI watchdog so that spinlock
 428           deadlocks are also debuggable.
 429
 430 config DEBUG_MUTEXES
 431         bool "Mutex debugging: basic checks"
 432         depends on DEBUG_KERNEL
 433         help
 434          This feature allows mutex semantics violations to be detected and
 435          reported.
 436
 437 config DEBUG_LOCK_ALLOC
 438         bool "Lock debugging: detect incorrect freeing of live locks"
 439         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 440         select DEBUG_SPINLOCK
 441         select DEBUG_MUTEXES
 442         select LOCKDEP
 443         help
 444          This feature will check whether any held lock (spinlock, rwlock,
 445          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 446          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 447          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 448          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 449          held during task exit.
 450
 451 config PROVE_LOCKING
 452         bool "Lock debugging: prove locking correctness"
 453         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 454         select LOCKDEP
 455         select DEBUG_SPINLOCK
 456         select DEBUG_MUTEXES
 457         select DEBUG_LOCK_ALLOC
 458         default n
 459         help
 460          This feature enables the kernel to prove that all locking
 461          that occurs in the kernel runtime is mathematically
 462          correct: that under no circumstance could an arbitrary (and
 463          not yet triggered) combination of observed locking
 464          sequences (on an arbitrary number of CPUs, running an
 465          arbitrary number of tasks and interrupt contexts) cause a
 466          deadlock.
 467
 468          In short, this feature enables the kernel to report locking
 469          related deadlocks before they actually occur.
 470
 471          The proof does not depend on how hard and complex a
 472          deadlock scenario would be to trigger: how many
 473          participant CPUs, tasks and irq-contexts would be needed
 474          for it to trigger. The proof also does not depend on
 475          timing: if a race and a resulting deadlock is possible
 476          theoretically (no matter how unlikely the race scenario
 477          is), it will be proven so and will immediately be
 478          reported by the kernel (once the event is observed that
 479          makes the deadlock theoretically possible).
 480
 481          If a deadlock is impossible (i.e. the locking rules, as
 482          observed by the kernel, are mathematically correct), the
 483          kernel reports nothing.
 484
 485          NOTE: this feature can also be enabled for rwlocks, mutexes
 486          and rwsems - in which case all dependencies between these
 487          different locking variants are observed and mapped too, and
 488          the proof of observed correctness is also maintained for an
 489          arbitrary combination of these separate locking variants.
 490
 491          For more details, see Documentation/lockdep-design.txt.
 492
 493 config LOCKDEP
 494         bool
 495         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 496         select STACKTRACE
 497         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
 498         select KALLSYMS
 499         select KALLSYMS_ALL
 500
 501 config LOCK_STAT
 502         bool "Lock usage statistics"
 503         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 504         select LOCKDEP
 505         select DEBUG_SPINLOCK
 506         select DEBUG_MUTEXES
 507         select DEBUG_LOCK_ALLOC
 508         default n
 509         help
 510          This feature enables tracking lock contention points
 511
 512          For more details, see Documentation/lockstat.txt
 513
 514 config DEBUG_LOCKDEP
 515         bool "Lock dependency engine debugging"
 516         depends on DEBUG_KERNEL && LOCKDEP
 517         help
 518           If you say Y here, the lock dependency engine will do
 519           additional runtime checks to debug itself, at the price
 520           of more runtime overhead.
 521
 522 config TRACE_IRQFLAGS
 523         depends on DEBUG_KERNEL
 524         bool
 525         default y
 526         depends on TRACE_IRQFLAGS_SUPPORT
 527         depends on PROVE_LOCKING
 528
 529 config DEBUG_SPINLOCK_SLEEP
 530         bool "Spinlock debugging: sleep-inside-spinlock checking"
 531         depends on DEBUG_KERNEL
 532         help
 533           If you say Y here, various routines which may sleep will become very
 534           noisy if they are called with a spinlock held.
 535
 536 config DEBUG_LOCKING_API_SELFTESTS
 537         bool "Locking API boot-time self-tests"
 538         depends on DEBUG_KERNEL
 539         help
 540           Say Y here if you want the kernel to run a short self-test during
 541           bootup. The self-test checks whether common types of locking bugs
 542           are detected by debugging mechanisms or not. (if you disable
 543           lock debugging then those bugs wont be detected of course.)
 544           The following locking APIs are covered: spinlocks, rwlocks,
 545           mutexes and rwsems.
 546
 547 config STACKTRACE
 548         bool
 549         depends on STACKTRACE_SUPPORT
 550
 551 config DEBUG_KOBJECT
 552         bool "kobject debugging"
 553         depends on DEBUG_KERNEL
 554         help
 555           If you say Y here, some extra kobject debugging messages will be sent
 556           to the syslog.
 557
 558 config DEBUG_HIGHMEM
 559         bool "Highmem debugging"
 560         depends on DEBUG_KERNEL && HIGHMEM
 561         help
 562           This options enables addition error checking for high memory systems.
 563           Disable for production systems.
 564
 565 config DEBUG_BUGVERBOSE
 566         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 567         depends on BUG
 568         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 569                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 570         default !EMBEDDED
 571         help
 572           Say Y here to make BUG() panics output the file name and line number
 573           of the BUG call as well as the EIP and oops trace.  This aids
 574           debugging but costs about 70-100K of memory.
 575
 576 config DEBUG_INFO
 577         bool "Compile the kernel with debug info"
 578         depends on DEBUG_KERNEL
 579         help
 580           If you say Y here the resulting kernel image will include
 581           debugging info resulting in a larger kernel image.
 582           This adds debug symbols to the kernel and modules (gcc -g), and
 583           is needed if you intend to use kernel crashdump or binary object
 584           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 585           Say Y here only if you plan to debug the kernel.
 586
 587           If unsure, say N.
 588
 589 config DEBUG_VM
 590         bool "Debug VM"
 591         depends on DEBUG_KERNEL
 592         help
 593           Enable this to turn on extended checks in the virtual-memory system
 594           that may impact performance.
 595
 596           If unsure, say N.
 597
 598 config DEBUG_VIRTUAL
 599         bool "Debug VM translations"
 600         depends on DEBUG_KERNEL && X86
 601         help
 602           Enable some costly sanity checks in virtual to page code. This can
 603           catch mistakes with virt_to_page() and friends.
 604
 605           If unsure, say N.
 606
 607 config DEBUG_NOMMU_REGIONS
 608         bool "Debug the global anon/private NOMMU mapping region tree"
 609         depends on DEBUG_KERNEL && !MMU
 610         help
 611           This option causes the global tree of anonymous and private mapping
 612           regions to be regularly checked for invalid topology.
 613
 614 config DEBUG_WRITECOUNT
 615         bool "Debug filesystem writers count"
 616         depends on DEBUG_KERNEL
 617         help
 618           Enable this to catch wrong use of the writers count in struct
 619           vfsmount.  This will increase the size of each file struct by
 620           32 bits.
 621
 622           If unsure, say N.
 623
 624 config DEBUG_MEMORY_INIT
 625         bool "Debug memory initialisation" if EMBEDDED
 626         default !EMBEDDED
 627         help
 628           Enable this for additional checks during memory initialisation.
 629           The sanity checks verify aspects of the VM such as the memory model
 630           and other information provided by the architecture. Verbose
 631           information will be printed at KERN_DEBUG loglevel depending
 632           on the mminit_loglevel= command-line option.
 633
 634           If unsure, say Y
 635
 636 config DEBUG_LIST
 637         bool "Debug linked list manipulation"
 638         depends on DEBUG_KERNEL
 639         help
 640           Enable this to turn on extended checks in the linked-list
 641           walking routines.
 642
 643           If unsure, say N.
 644
 645 config DEBUG_SG
 646         bool "Debug SG table operations"
 647         depends on DEBUG_KERNEL
 648         help
 649           Enable this to turn on checks on scatter-gather tables. This can
 650           help find problems with drivers that do not properly initialize
 651           their sg tables.
 652
 653           If unsure, say N.
 654
 655 config DEBUG_NOTIFIERS
 656         bool "Debug notifier call chains"
 657         depends on DEBUG_KERNEL
 658         help
 659           Enable this to turn on sanity checking for notifier call chains.
 660           This is most useful for kernel developers to make sure that
 661           modules properly unregister themselves from notifier chains.
 662           This is a relatively cheap check but if you care about maximum
 663           performance, say N.
 664
 665 config DEBUG_CREDENTIALS
 666         bool "Debug credential management"
 667         depends on DEBUG_KERNEL
 668         help
 669           Enable this to turn on some debug checking for credential
 670           management.  The additional code keeps track of the number of
 671           pointers from task_structs to any given cred struct, and checks to
 672           see that this number never exceeds the usage count of the cred
 673           struct.
 674
 675           Furthermore, if SELinux is enabled, this also checks that the
 676           security pointer in the cred struct is never seen to be invalid.
 677
 678           If unsure, say N.
 679
 680 #
 681 # Select this config option from the architecture Kconfig, if it
 682 # it is preferred to always offer frame pointers as a config
 683 # option on the architecture (regardless of KERNEL_DEBUG):
 684 #
 685 config ARCH_WANT_FRAME_POINTERS
 686         bool
 687         help
 688
 689 config FRAME_POINTER
 690         bool "Compile the kernel with frame pointers"
 691         depends on DEBUG_KERNEL && \
 692                 (CRIS || M68K || M68KNOMMU || FRV || UML || \
 693                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 694                 ARCH_WANT_FRAME_POINTERS
 695         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 696         help
 697           If you say Y here the resulting kernel image will be slightly
 698           larger and slower, but it gives very useful debugging information
 699           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 700
 701 config BOOT_PRINTK_DELAY
 702         bool "Delay each boot printk message by N milliseconds"
 703         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 704         help
 705           This build option allows you to read kernel boot messages
 706           by inserting a short delay after each one.  The delay is
 707           specified in milliseconds on the kernel command line,
 708           using "boot_delay=N".
 709
 710           It is likely that you would also need to use "lpj=M" to preset
 711           the "loops per jiffie" value.
 712           See a previous boot log for the "lpj" value to use for your
 713           system, and then set "lpj=M" before setting "boot_delay=N".
 714           NOTE:  Using this option may adversely affect SMP systems.
 715           I.e., processors other than the first one may not boot up.
 716           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 717           what it believes to be lockup conditions.
 718
 719 config RCU_TORTURE_TEST
 720         tristate "torture tests for RCU"
 721         depends on DEBUG_KERNEL
 722         default n
 723         help
 724           This option provides a kernel module that runs torture tests
 725           on the RCU infrastructure.  The kernel module may be built
 726           after the fact on the running kernel to be tested, if desired.
 727
 728           Say Y here if you want RCU torture tests to be built into
 729           the kernel.
 730           Say M if you want the RCU torture tests to build as a module.
 731           Say N if you are unsure.
 732
 733 config RCU_TORTURE_TEST_RUNNABLE
 734         bool "torture tests for RCU runnable by default"
 735         depends on RCU_TORTURE_TEST = y
 736         default n
 737         help
 738           This option provides a way to build the RCU torture tests
 739           directly into the kernel without them starting up at boot
 740           time.  You can use /proc/sys/kernel/rcutorture_runnable
 741           to manually override this setting.  This /proc file is
 742           available only when the RCU torture tests have been built
 743           into the kernel.
 744
 745           Say Y here if you want the RCU torture tests to start during
 746           boot (you probably don't).
 747           Say N here if you want the RCU torture tests to start only
 748           after being manually enabled via /proc.
 749
 750 config RCU_CPU_STALL_DETECTOR
 751         bool "Check for stalled CPUs delaying RCU grace periods"
 752         depends on TREE_RCU || TREE_PREEMPT_RCU
 753         default n
 754         help
 755           This option causes RCU to printk information on which
 756           CPUs are delaying the current grace period, but only when
 757           the grace period extends for excessive time periods.
 758
 759           Say Y if you want RCU to perform such checks.
 760
 761           Say N if you are unsure.
 762
 763 config KPROBES_SANITY_TEST
 764         bool "Kprobes sanity tests"
 765         depends on DEBUG_KERNEL
 766         depends on KPROBES
 767         default n
 768         help
 769           This option provides for testing basic kprobes functionality on
 770           boot. A sample kprobe, jprobe and kretprobe are inserted and
 771           verified for functionality.
 772
 773           Say N if you are unsure.
 774
 775 config BACKTRACE_SELF_TEST
 776         tristate "Self test for the backtrace code"
 777         depends on DEBUG_KERNEL
 778         default n
 779         help
 780           This option provides a kernel module that can be used to test
 781           the kernel stack backtrace code. This option is not useful
 782           for distributions or general kernels, but only for kernel
 783           developers working on architecture code.
 784
 785           Note that if you want to also test saved backtraces, you will
 786           have to enable STACKTRACE as well.
 787
 788           Say N if you are unsure.
 789
 790 config DEBUG_BLOCK_EXT_DEVT
 791         bool "Force extended block device numbers and spread them"
 792         depends on DEBUG_KERNEL
 793         depends on BLOCK
 794         default n
 795         help
 796           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 797           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 798           YOU ARE DOING.  Distros, please enable this and fix whatever
 799           is broken.
 800
 801           Conventionally, block device numbers are allocated from
 802           predetermined contiguous area.  However, extended block area
 803           may introduce non-contiguous block device numbers.  This
 804           option forces most block device numbers to be allocated from
 805           the extended space and spreads them to discover kernel or
 806           userland code paths which assume predetermined contiguous
 807           device number allocation.
 808
 809           Note that turning on this debug option shuffles all the
 810           device numbers for all IDE and SCSI devices including libata
 811           ones, so root partition specified using device number
 812           directly (via rdev or root=MAJ:MIN) won't work anymore.
 813           Textual device names (root=/dev/sdXn) will continue to work.
 814
 815           Say N if you are unsure.
 816
 817 config DEBUG_FORCE_WEAK_PER_CPU
 818         bool "Force weak per-cpu definitions"
 819         depends on DEBUG_KERNEL
 820         help
 821           s390 and alpha require percpu variables in modules to be
 822           defined weak to work around addressing range issue which
 823           puts the following two restrictions on percpu variable
 824           definitions.
 825
 826           1. percpu symbols must be unique whether static or not
 827           2. percpu variables can't be defined inside a function
 828
 829           To ensure that generic code follows the above rules, this
 830           option forces all percpu variables to be defined as weak.
 831
 832 config LKDTM
 833         tristate "Linux Kernel Dump Test Tool Module"
 834         depends on DEBUG_KERNEL
 835         depends on KPROBES
 836         depends on BLOCK
 837         default n
 838         help
 839         This module enables testing of the different dumping mechanisms by
 840         inducing system failures at predefined crash points.
 841         If you don't need it: say N
 842         Choose M here to compile this code as a module. The module will be
 843         called lkdtm.
 844
 845         Documentation on how to use the module can be found in
 846         drivers/misc/lkdtm.c
 847
 848 config FAULT_INJECTION
 849         bool "Fault-injection framework"
 850         depends on DEBUG_KERNEL
 851         help
 852           Provide fault-injection framework.
 853           For more details, see Documentation/fault-injection/.
 854
 855 config FAILSLAB
 856         bool "Fault-injection capability for kmalloc"
 857         depends on FAULT_INJECTION
 858         depends on SLAB || SLUB
 859         help
 860           Provide fault-injection capability for kmalloc.
 861
 862 config FAIL_PAGE_ALLOC
 863         bool "Fault-injection capabilitiy for alloc_pages()"
 864         depends on FAULT_INJECTION
 865         help
 866           Provide fault-injection capability for alloc_pages().
 867
 868 config FAIL_MAKE_REQUEST
 869         bool "Fault-injection capability for disk IO"
 870         depends on FAULT_INJECTION && BLOCK
 871         help
 872           Provide fault-injection capability for disk IO.
 873
 874 config FAIL_IO_TIMEOUT
 875         bool "Faul-injection capability for faking disk interrupts"
 876         depends on FAULT_INJECTION && BLOCK
 877         help
 878           Provide fault-injection capability on end IO handling. This
 879           will make the block layer "forget" an interrupt as configured,
 880           thus exercising the error handling.
 881
 882           Only works with drivers that use the generic timeout handling,
 883           for others it wont do anything.
 884
 885 config FAULT_INJECTION_DEBUG_FS
 886         bool "Debugfs entries for fault-injection capabilities"
 887         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 888         help
 889           Enable configuration of fault-injection capabilities via debugfs.
 890
 891 config FAULT_INJECTION_STACKTRACE_FILTER
 892         bool "stacktrace filter for fault-injection capabilities"
 893         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 894         depends on !X86_64
 895         select STACKTRACE
 896         select FRAME_POINTER if !PPC && !S390
 897         help
 898           Provide stacktrace filter for fault-injection capabilities
 899
 900 config LATENCYTOP
 901         bool "Latency measuring infrastructure"
 902         select FRAME_POINTER if !MIPS && !PPC && !S390
 903         select KALLSYMS
 904         select KALLSYMS_ALL
 905         select STACKTRACE
 906         select SCHEDSTATS
 907         select SCHED_DEBUG
 908         depends on HAVE_LATENCYTOP_SUPPORT
 909         help
 910           Enable this option if you want to use the LatencyTOP tool
 911           to find out which userspace is blocking on what kernel operations.
 912
 913 config SYSCTL_SYSCALL_CHECK
 914         bool "Sysctl checks"
 915         depends on SYSCTL_SYSCALL
 916         ---help---
 917           sys_sysctl uses binary paths that have been found challenging
 918           to properly maintain and use. This enables checks that help
 919           you to keep things correct.
 920
 921 source mm/Kconfig.debug
 922 source kernel/trace/Kconfig
 923
 924 config PROVIDE_OHCI1394_DMA_INIT
 925         bool "Remote debugging over FireWire early on boot"
 926         depends on PCI && X86
 927         help
 928           If you want to debug problems which hang or crash the kernel early
 929           on boot and the crashing machine has a FireWire port, you can use
 930           this feature to remotely access the memory of the crashed machine
 931           over FireWire. This employs remote DMA as part of the OHCI1394
 932           specification which is now the standard for FireWire controllers.
 933
 934           With remote DMA, you can monitor the printk buffer remotely using
 935           firescope and access all memory below 4GB using fireproxy from gdb.
 936           Even controlling a kernel debugger is possible using remote DMA.
 937
 938           Usage:
 939
 940           If ohci1394_dma=early is used as boot parameter, it will initialize
 941           all OHCI1394 controllers which are found in the PCI config space.
 942
 943           As all changes to the FireWire bus such as enabling and disabling
 944           devices cause a bus reset and thereby disable remote DMA for all
 945           devices, be sure to have the cable plugged and FireWire enabled on
 946           the debugging host before booting the debug target for debugging.
 947
 948           This code (~1k) is freed after boot. By then, the firewire stack
 949           in charge of the OHCI-1394 controllers should be used instead.
 950
 951           See Documentation/debugging-via-ohci1394.txt for more information.
 952
 953 config FIREWIRE_OHCI_REMOTE_DMA
 954         bool "Remote debugging over FireWire with firewire-ohci"
 955         depends on FIREWIRE_OHCI
 956         help
 957           This option lets you use the FireWire bus for remote debugging
 958           with help of the firewire-ohci driver. It enables unfiltered
 959           remote DMA in firewire-ohci.
 960           See Documentation/debugging-via-ohci1394.txt for more information.
 961
 962           If unsure, say N.
 963
 964 config BUILD_DOCSRC
 965         bool "Build targets in Documentation/ tree"
 966         depends on HEADERS_CHECK
 967         help
 968           This option attempts to build objects from the source files in the
 969           kernel Documentation/ tree.
 970
 971           Say N if you are unsure.
 972
 973 config DYNAMIC_DEBUG
 974         bool "Enable dynamic printk() support"
 975         default n
 976         depends on PRINTK
 977         depends on DEBUG_FS
 978         help
 979
 980           Compiles debug level messages into the kernel, which would not
 981           otherwise be available at runtime. These messages can then be
 982           enabled/disabled based on various levels of scope - per source file,
 983           function, module, format string, and line number. This mechanism
 984           implicitly enables all pr_debug() and dev_dbg() calls. The impact of
 985           this compile option is a larger kernel text size of about 2%.
 986
 987           Usage:
 988
 989           Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
 990           which is contained in the 'debugfs' filesystem. Thus, the debugfs
 991           filesystem must first be mounted before making use of this feature.
 992           We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
 993           file contains a list of the debug statements that can be enabled. The
 994           format for each line of the file is:
 995
 996                 filename:lineno [module]function flags format
 997
 998           filename : source file of the debug statement
 999           lineno : line number of the debug statement
1000           module : module that contains the debug statement
1001           function : function that contains the debug statement
1002           flags : 'p' means the line is turned 'on' for printing
1003           format : the format used for the debug statement
1004
1005           From a live system:
1006
1007                 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
1008                 # filename:lineno [module]function flags format
1009                 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1010                 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1011                 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1012
1013           Example usage:
1014
1015                 // enable the message at line 1603 of file svcsock.c
1016                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1017                                                 <debugfs>/dynamic_debug/ddebug
1018
1019                 // enable all the messages in file svcsock.c
1020                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1021                                                 <debugfs>/dynamic_debug/ddebug
1022
1023                 // enable all the messages in the NFS server module
1024                 nullarbor:~ # echo -n 'module nfsd +p' >
1025                                                 <debugfs>/dynamic_debug/ddebug
1026
1027                 // enable all 12 messages in the function svc_process()
1028                 nullarbor:~ # echo -n 'func svc_process +p' >
1029                                                 <debugfs>/dynamic_debug/ddebug
1030
1031                 // disable all 12 messages in the function svc_process()
1032                 nullarbor:~ # echo -n 'func svc_process -p' >
1033                                                 <debugfs>/dynamic_debug/ddebug
1034
1035           See Documentation/dynamic-debug-howto.txt for additional information.
1036
1037 config DMA_API_DEBUG
1038         bool "Enable debugging of DMA-API usage"
1039         depends on HAVE_DMA_API_DEBUG
1040         help
1041           Enable this option to debug the use of the DMA API by device drivers.
1042           With this option you will be able to detect common bugs in device
1043           drivers like double-freeing of DMA mappings or freeing mappings that
1044           were never allocated.
1045           This option causes a performance degredation.  Use only if you want
1046           to debug device drivers. If unsure, say N.
1047
1048 source "samples/Kconfig"
1049
1050 source "lib/Kconfig.kgdb"
1051
1052 source "lib/Kconfig.kmemcheck"