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_WORK
 302         bool "Debug work objects"
 303         depends on DEBUG_OBJECTS
 304         help
 305           If you say Y here, additional code will be inserted into the
 306           work queue routines to track the life time of work objects and
 307           validate the work operations.
 308
 309 config DEBUG_OBJECTS_ENABLE_DEFAULT
 310         int "debug_objects bootup default value (0-1)"
 311         range 0 1
 312         default "1"
 313         depends on DEBUG_OBJECTS
 314         help
 315           Debug objects boot parameter default value
 316
 317 config DEBUG_SLAB
 318         bool "Debug slab memory allocations"
 319         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 320         help
 321           Say Y here to have the kernel do limited verification on memory
 322           allocation as well as poisoning memory on free to catch use of freed
 323           memory. This can make kmalloc/kfree-intensive workloads much slower.
 324
 325 config DEBUG_SLAB_LEAK
 326         bool "Memory leak debugging"
 327         depends on DEBUG_SLAB
 328
 329 config SLUB_DEBUG_ON
 330         bool "SLUB debugging on by default"
 331         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 332         default n
 333         help
 334           Boot with debugging on by default. SLUB boots by default with
 335           the runtime debug capabilities switched off. Enabling this is
 336           equivalent to specifying the "slub_debug" parameter on boot.
 337           There is no support for more fine grained debug control like
 338           possible with slub_debug=xxx. SLUB debugging may be switched
 339           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 340           "slub_debug=-".
 341
 342 config SLUB_STATS
 343         default n
 344         bool "Enable SLUB performance statistics"
 345         depends on SLUB && SLUB_DEBUG && SYSFS
 346         help
 347           SLUB statistics are useful to debug SLUBs allocation behavior in
 348           order find ways to optimize the allocator. This should never be
 349           enabled for production use since keeping statistics slows down
 350           the allocator by a few percentage points. The slabinfo command
 351           supports the determination of the most active slabs to figure
 352           out which slabs are relevant to a particular load.
 353           Try running: slabinfo -DA
 354
 355 config DEBUG_KMEMLEAK
 356         bool "Kernel memory leak detector"
 357         depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
 358                 (X86 || ARM || PPC || S390 || SUPERH)
 359
 360         select DEBUG_FS if SYSFS
 361         select STACKTRACE if STACKTRACE_SUPPORT
 362         select KALLSYMS
 363         select CRC32
 364         help
 365           Say Y here if you want to enable the memory leak
 366           detector. The memory allocation/freeing is traced in a way
 367           similar to the Boehm's conservative garbage collector, the
 368           difference being that the orphan objects are not freed but
 369           only shown in /sys/kernel/debug/kmemleak. Enabling this
 370           feature will introduce an overhead to memory
 371           allocations. See Documentation/kmemleak.txt for more
 372           details.
 373
 374           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 375           of finding leaks due to the slab objects poisoning.
 376
 377           In order to access the kmemleak file, debugfs needs to be
 378           mounted (usually at /sys/kernel/debug).
 379
 380 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 381         int "Maximum kmemleak early log entries"
 382         depends on DEBUG_KMEMLEAK
 383         range 200 40000
 384         default 400
 385         help
 386           Kmemleak must track all the memory allocations to avoid
 387           reporting false positives. Since memory may be allocated or
 388           freed before kmemleak is initialised, an early log buffer is
 389           used to store these actions. If kmemleak reports "early log
 390           buffer exceeded", please increase this value.
 391
 392 config DEBUG_KMEMLEAK_TEST
 393         tristate "Simple test for the kernel memory leak detector"
 394         depends on DEBUG_KMEMLEAK
 395         help
 396           Say Y or M here to build a test for the kernel memory leak
 397           detector. This option enables a module that explicitly leaks
 398           memory.
 399
 400           If unsure, say N.
 401
 402 config DEBUG_PREEMPT
 403         bool "Debug preemptible kernel"
 404         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 405         default y
 406         help
 407           If you say Y here then the kernel will use a debug variant of the
 408           commonly used smp_processor_id() function and will print warnings
 409           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 410           will detect preemption count underflows.
 411
 412 config DEBUG_RT_MUTEXES
 413         bool "RT Mutex debugging, deadlock detection"
 414         depends on DEBUG_KERNEL && RT_MUTEXES
 415         help
 416          This allows rt mutex semantics violations and rt mutex related
 417          deadlocks (lockups) to be detected and reported automatically.
 418
 419 config DEBUG_PI_LIST
 420         bool
 421         default y
 422         depends on DEBUG_RT_MUTEXES
 423
 424 config RT_MUTEX_TESTER
 425         bool "Built-in scriptable tester for rt-mutexes"
 426         depends on DEBUG_KERNEL && RT_MUTEXES
 427         help
 428           This option enables a rt-mutex tester.
 429
 430 config DEBUG_SPINLOCK
 431         bool "Spinlock and rw-lock debugging: basic checks"
 432         depends on DEBUG_KERNEL
 433         help
 434           Say Y here and build SMP to catch missing spinlock initialization
 435           and certain other kinds of spinlock errors commonly made.  This is
 436           best used in conjunction with the NMI watchdog so that spinlock
 437           deadlocks are also debuggable.
 438
 439 config DEBUG_MUTEXES
 440         bool "Mutex debugging: basic checks"
 441         depends on DEBUG_KERNEL
 442         help
 443          This feature allows mutex semantics violations to be detected and
 444          reported.
 445
 446 config DEBUG_LOCK_ALLOC
 447         bool "Lock debugging: detect incorrect freeing of live locks"
 448         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 449         select DEBUG_SPINLOCK
 450         select DEBUG_MUTEXES
 451         select LOCKDEP
 452         help
 453          This feature will check whether any held lock (spinlock, rwlock,
 454          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 455          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 456          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 457          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 458          held during task exit.
 459
 460 config PROVE_LOCKING
 461         bool "Lock debugging: prove locking correctness"
 462         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 463         select LOCKDEP
 464         select DEBUG_SPINLOCK
 465         select DEBUG_MUTEXES
 466         select DEBUG_LOCK_ALLOC
 467         default n
 468         help
 469          This feature enables the kernel to prove that all locking
 470          that occurs in the kernel runtime is mathematically
 471          correct: that under no circumstance could an arbitrary (and
 472          not yet triggered) combination of observed locking
 473          sequences (on an arbitrary number of CPUs, running an
 474          arbitrary number of tasks and interrupt contexts) cause a
 475          deadlock.
 476
 477          In short, this feature enables the kernel to report locking
 478          related deadlocks before they actually occur.
 479
 480          The proof does not depend on how hard and complex a
 481          deadlock scenario would be to trigger: how many
 482          participant CPUs, tasks and irq-contexts would be needed
 483          for it to trigger. The proof also does not depend on
 484          timing: if a race and a resulting deadlock is possible
 485          theoretically (no matter how unlikely the race scenario
 486          is), it will be proven so and will immediately be
 487          reported by the kernel (once the event is observed that
 488          makes the deadlock theoretically possible).
 489
 490          If a deadlock is impossible (i.e. the locking rules, as
 491          observed by the kernel, are mathematically correct), the
 492          kernel reports nothing.
 493
 494          NOTE: this feature can also be enabled for rwlocks, mutexes
 495          and rwsems - in which case all dependencies between these
 496          different locking variants are observed and mapped too, and
 497          the proof of observed correctness is also maintained for an
 498          arbitrary combination of these separate locking variants.
 499
 500          For more details, see Documentation/lockdep-design.txt.
 501
 502 config PROVE_RCU
 503         bool "RCU debugging: prove RCU correctness"
 504         depends on PROVE_LOCKING
 505         default n
 506         help
 507          This feature enables lockdep extensions that check for correct
 508          use of RCU APIs.  This is currently under development.  Say Y
 509          if you want to debug RCU usage or help work on the PROVE_RCU
 510          feature.
 511
 512          Say N if you are unsure.
 513
 514 config LOCKDEP
 515         bool
 516         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 517         select STACKTRACE
 518         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
 519         select KALLSYMS
 520         select KALLSYMS_ALL
 521
 522 config LOCK_STAT
 523         bool "Lock usage statistics"
 524         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 525         select LOCKDEP
 526         select DEBUG_SPINLOCK
 527         select DEBUG_MUTEXES
 528         select DEBUG_LOCK_ALLOC
 529         default n
 530         help
 531          This feature enables tracking lock contention points
 532
 533          For more details, see Documentation/lockstat.txt
 534
 535          This also enables lock events required by "perf lock",
 536          subcommand of perf.
 537          If you want to use "perf lock", you also need to turn on
 538          CONFIG_EVENT_TRACING.
 539
 540          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 541          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 542
 543 config DEBUG_LOCKDEP
 544         bool "Lock dependency engine debugging"
 545         depends on DEBUG_KERNEL && LOCKDEP
 546         help
 547           If you say Y here, the lock dependency engine will do
 548           additional runtime checks to debug itself, at the price
 549           of more runtime overhead.
 550
 551 config TRACE_IRQFLAGS
 552         depends on DEBUG_KERNEL
 553         bool
 554         default y
 555         depends on TRACE_IRQFLAGS_SUPPORT
 556         depends on PROVE_LOCKING
 557
 558 config DEBUG_SPINLOCK_SLEEP
 559         bool "Spinlock debugging: sleep-inside-spinlock checking"
 560         depends on DEBUG_KERNEL
 561         help
 562           If you say Y here, various routines which may sleep will become very
 563           noisy if they are called with a spinlock held.
 564
 565 config DEBUG_LOCKING_API_SELFTESTS
 566         bool "Locking API boot-time self-tests"
 567         depends on DEBUG_KERNEL
 568         help
 569           Say Y here if you want the kernel to run a short self-test during
 570           bootup. The self-test checks whether common types of locking bugs
 571           are detected by debugging mechanisms or not. (if you disable
 572           lock debugging then those bugs wont be detected of course.)
 573           The following locking APIs are covered: spinlocks, rwlocks,
 574           mutexes and rwsems.
 575
 576 config STACKTRACE
 577         bool
 578         depends on STACKTRACE_SUPPORT
 579
 580 config DEBUG_KOBJECT
 581         bool "kobject debugging"
 582         depends on DEBUG_KERNEL
 583         help
 584           If you say Y here, some extra kobject debugging messages will be sent
 585           to the syslog.
 586
 587 config DEBUG_HIGHMEM
 588         bool "Highmem debugging"
 589         depends on DEBUG_KERNEL && HIGHMEM
 590         help
 591           This options enables addition error checking for high memory systems.
 592           Disable for production systems.
 593
 594 config DEBUG_BUGVERBOSE
 595         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 596         depends on BUG
 597         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 598                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 599         default y
 600         help
 601           Say Y here to make BUG() panics output the file name and line number
 602           of the BUG call as well as the EIP and oops trace.  This aids
 603           debugging but costs about 70-100K of memory.
 604
 605 config DEBUG_INFO
 606         bool "Compile the kernel with debug info"
 607         depends on DEBUG_KERNEL
 608         help
 609           If you say Y here the resulting kernel image will include
 610           debugging info resulting in a larger kernel image.
 611           This adds debug symbols to the kernel and modules (gcc -g), and
 612           is needed if you intend to use kernel crashdump or binary object
 613           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 614           Say Y here only if you plan to debug the kernel.
 615
 616           If unsure, say N.
 617
 618 config DEBUG_VM
 619         bool "Debug VM"
 620         depends on DEBUG_KERNEL
 621         help
 622           Enable this to turn on extended checks in the virtual-memory system
 623           that may impact performance.
 624
 625           If unsure, say N.
 626
 627 config DEBUG_VIRTUAL
 628         bool "Debug VM translations"
 629         depends on DEBUG_KERNEL && X86
 630         help
 631           Enable some costly sanity checks in virtual to page code. This can
 632           catch mistakes with virt_to_page() and friends.
 633
 634           If unsure, say N.
 635
 636 config DEBUG_NOMMU_REGIONS
 637         bool "Debug the global anon/private NOMMU mapping region tree"
 638         depends on DEBUG_KERNEL && !MMU
 639         help
 640           This option causes the global tree of anonymous and private mapping
 641           regions to be regularly checked for invalid topology.
 642
 643 config DEBUG_WRITECOUNT
 644         bool "Debug filesystem writers count"
 645         depends on DEBUG_KERNEL
 646         help
 647           Enable this to catch wrong use of the writers count in struct
 648           vfsmount.  This will increase the size of each file struct by
 649           32 bits.
 650
 651           If unsure, say N.
 652
 653 config DEBUG_MEMORY_INIT
 654         bool "Debug memory initialisation" if EMBEDDED
 655         default !EMBEDDED
 656         help
 657           Enable this for additional checks during memory initialisation.
 658           The sanity checks verify aspects of the VM such as the memory model
 659           and other information provided by the architecture. Verbose
 660           information will be printed at KERN_DEBUG loglevel depending
 661           on the mminit_loglevel= command-line option.
 662
 663           If unsure, say Y
 664
 665 config DEBUG_LIST
 666         bool "Debug linked list manipulation"
 667         depends on DEBUG_KERNEL
 668         help
 669           Enable this to turn on extended checks in the linked-list
 670           walking routines.
 671
 672           If unsure, say N.
 673
 674 config DEBUG_SG
 675         bool "Debug SG table operations"
 676         depends on DEBUG_KERNEL
 677         help
 678           Enable this to turn on checks on scatter-gather tables. This can
 679           help find problems with drivers that do not properly initialize
 680           their sg tables.
 681
 682           If unsure, say N.
 683
 684 config DEBUG_NOTIFIERS
 685         bool "Debug notifier call chains"
 686         depends on DEBUG_KERNEL
 687         help
 688           Enable this to turn on sanity checking for notifier call chains.
 689           This is most useful for kernel developers to make sure that
 690           modules properly unregister themselves from notifier chains.
 691           This is a relatively cheap check but if you care about maximum
 692           performance, say N.
 693
 694 config DEBUG_CREDENTIALS
 695         bool "Debug credential management"
 696         depends on DEBUG_KERNEL
 697         help
 698           Enable this to turn on some debug checking for credential
 699           management.  The additional code keeps track of the number of
 700           pointers from task_structs to any given cred struct, and checks to
 701           see that this number never exceeds the usage count of the cred
 702           struct.
 703
 704           Furthermore, if SELinux is enabled, this also checks that the
 705           security pointer in the cred struct is never seen to be invalid.
 706
 707           If unsure, say N.
 708
 709 #
 710 # Select this config option from the architecture Kconfig, if it
 711 # it is preferred to always offer frame pointers as a config
 712 # option on the architecture (regardless of KERNEL_DEBUG):
 713 #
 714 config ARCH_WANT_FRAME_POINTERS
 715         bool
 716         help
 717
 718 config FRAME_POINTER
 719         bool "Compile the kernel with frame pointers"
 720         depends on DEBUG_KERNEL && \
 721                 (CRIS || M68K || M68KNOMMU || FRV || UML || \
 722                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 723                 ARCH_WANT_FRAME_POINTERS
 724         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 725         help
 726           If you say Y here the resulting kernel image will be slightly
 727           larger and slower, but it gives very useful debugging information
 728           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 729
 730 config BOOT_PRINTK_DELAY
 731         bool "Delay each boot printk message by N milliseconds"
 732         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 733         help
 734           This build option allows you to read kernel boot messages
 735           by inserting a short delay after each one.  The delay is
 736           specified in milliseconds on the kernel command line,
 737           using "boot_delay=N".
 738
 739           It is likely that you would also need to use "lpj=M" to preset
 740           the "loops per jiffie" value.
 741           See a previous boot log for the "lpj" value to use for your
 742           system, and then set "lpj=M" before setting "boot_delay=N".
 743           NOTE:  Using this option may adversely affect SMP systems.
 744           I.e., processors other than the first one may not boot up.
 745           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 746           what it believes to be lockup conditions.
 747
 748 config RCU_TORTURE_TEST
 749         tristate "torture tests for RCU"
 750         depends on DEBUG_KERNEL
 751         default n
 752         help
 753           This option provides a kernel module that runs torture tests
 754           on the RCU infrastructure.  The kernel module may be built
 755           after the fact on the running kernel to be tested, if desired.
 756
 757           Say Y here if you want RCU torture tests to be built into
 758           the kernel.
 759           Say M if you want the RCU torture tests to build as a module.
 760           Say N if you are unsure.
 761
 762 config RCU_TORTURE_TEST_RUNNABLE
 763         bool "torture tests for RCU runnable by default"
 764         depends on RCU_TORTURE_TEST = y
 765         default n
 766         help
 767           This option provides a way to build the RCU torture tests
 768           directly into the kernel without them starting up at boot
 769           time.  You can use /proc/sys/kernel/rcutorture_runnable
 770           to manually override this setting.  This /proc file is
 771           available only when the RCU torture tests have been built
 772           into the kernel.
 773
 774           Say Y here if you want the RCU torture tests to start during
 775           boot (you probably don't).
 776           Say N here if you want the RCU torture tests to start only
 777           after being manually enabled via /proc.
 778
 779 config RCU_CPU_STALL_DETECTOR
 780         bool "Check for stalled CPUs delaying RCU grace periods"
 781         depends on TREE_RCU || TREE_PREEMPT_RCU
 782         default y
 783         help
 784           This option causes RCU to printk information on which
 785           CPUs are delaying the current grace period, but only when
 786           the grace period extends for excessive time periods.
 787
 788           Say N if you want to disable such checks.
 789
 790           Say Y if you are unsure.
 791
 792 config RCU_CPU_STALL_VERBOSE
 793         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 794         depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
 795         default n
 796         help
 797           This option causes RCU to printk detailed per-task information
 798           for any tasks that are stalling the current RCU grace period.
 799
 800           Say N if you are unsure.
 801
 802           Say Y if you want to enable such checks.
 803
 804 config KPROBES_SANITY_TEST
 805         bool "Kprobes sanity tests"
 806         depends on DEBUG_KERNEL
 807         depends on KPROBES
 808         default n
 809         help
 810           This option provides for testing basic kprobes functionality on
 811           boot. A sample kprobe, jprobe and kretprobe are inserted and
 812           verified for functionality.
 813
 814           Say N if you are unsure.
 815
 816 config BACKTRACE_SELF_TEST
 817         tristate "Self test for the backtrace code"
 818         depends on DEBUG_KERNEL
 819         default n
 820         help
 821           This option provides a kernel module that can be used to test
 822           the kernel stack backtrace code. This option is not useful
 823           for distributions or general kernels, but only for kernel
 824           developers working on architecture code.
 825
 826           Note that if you want to also test saved backtraces, you will
 827           have to enable STACKTRACE as well.
 828
 829           Say N if you are unsure.
 830
 831 config DEBUG_BLOCK_EXT_DEVT
 832         bool "Force extended block device numbers and spread them"
 833         depends on DEBUG_KERNEL
 834         depends on BLOCK
 835         default n
 836         help
 837           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 838           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 839           YOU ARE DOING.  Distros, please enable this and fix whatever
 840           is broken.
 841
 842           Conventionally, block device numbers are allocated from
 843           predetermined contiguous area.  However, extended block area
 844           may introduce non-contiguous block device numbers.  This
 845           option forces most block device numbers to be allocated from
 846           the extended space and spreads them to discover kernel or
 847           userland code paths which assume predetermined contiguous
 848           device number allocation.
 849
 850           Note that turning on this debug option shuffles all the
 851           device numbers for all IDE and SCSI devices including libata
 852           ones, so root partition specified using device number
 853           directly (via rdev or root=MAJ:MIN) won't work anymore.
 854           Textual device names (root=/dev/sdXn) will continue to work.
 855
 856           Say N if you are unsure.
 857
 858 config DEBUG_FORCE_WEAK_PER_CPU
 859         bool "Force weak per-cpu definitions"
 860         depends on DEBUG_KERNEL
 861         help
 862           s390 and alpha require percpu variables in modules to be
 863           defined weak to work around addressing range issue which
 864           puts the following two restrictions on percpu variable
 865           definitions.
 866
 867           1. percpu symbols must be unique whether static or not
 868           2. percpu variables can't be defined inside a function
 869
 870           To ensure that generic code follows the above rules, this
 871           option forces all percpu variables to be defined as weak.
 872
 873 config LKDTM
 874         tristate "Linux Kernel Dump Test Tool Module"
 875         depends on DEBUG_FS
 876         depends on BLOCK
 877         default n
 878         help
 879         This module enables testing of the different dumping mechanisms by
 880         inducing system failures at predefined crash points.
 881         If you don't need it: say N
 882         Choose M here to compile this code as a module. The module will be
 883         called lkdtm.
 884
 885         Documentation on how to use the module can be found in
 886         Documentation/fault-injection/provoke-crashes.txt
 887
 888 config FAULT_INJECTION
 889         bool "Fault-injection framework"
 890         depends on DEBUG_KERNEL
 891         help
 892           Provide fault-injection framework.
 893           For more details, see Documentation/fault-injection/.
 894
 895 config FAILSLAB
 896         bool "Fault-injection capability for kmalloc"
 897         depends on FAULT_INJECTION
 898         depends on SLAB || SLUB
 899         help
 900           Provide fault-injection capability for kmalloc.
 901
 902 config FAIL_PAGE_ALLOC
 903         bool "Fault-injection capabilitiy for alloc_pages()"
 904         depends on FAULT_INJECTION
 905         help
 906           Provide fault-injection capability for alloc_pages().
 907
 908 config FAIL_MAKE_REQUEST
 909         bool "Fault-injection capability for disk IO"
 910         depends on FAULT_INJECTION && BLOCK
 911         help
 912           Provide fault-injection capability for disk IO.
 913
 914 config FAIL_IO_TIMEOUT
 915         bool "Faul-injection capability for faking disk interrupts"
 916         depends on FAULT_INJECTION && BLOCK
 917         help
 918           Provide fault-injection capability on end IO handling. This
 919           will make the block layer "forget" an interrupt as configured,
 920           thus exercising the error handling.
 921
 922           Only works with drivers that use the generic timeout handling,
 923           for others it wont do anything.
 924
 925 config FAULT_INJECTION_DEBUG_FS
 926         bool "Debugfs entries for fault-injection capabilities"
 927         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 928         help
 929           Enable configuration of fault-injection capabilities via debugfs.
 930
 931 config FAULT_INJECTION_STACKTRACE_FILTER
 932         bool "stacktrace filter for fault-injection capabilities"
 933         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 934         depends on !X86_64
 935         select STACKTRACE
 936         select FRAME_POINTER if !PPC && !S390
 937         help
 938           Provide stacktrace filter for fault-injection capabilities
 939
 940 config LATENCYTOP
 941         bool "Latency measuring infrastructure"
 942         select FRAME_POINTER if !MIPS && !PPC && !S390
 943         select KALLSYMS
 944         select KALLSYMS_ALL
 945         select STACKTRACE
 946         select SCHEDSTATS
 947         select SCHED_DEBUG
 948         depends on HAVE_LATENCYTOP_SUPPORT
 949         help
 950           Enable this option if you want to use the LatencyTOP tool
 951           to find out which userspace is blocking on what kernel operations.
 952
 953 config SYSCTL_SYSCALL_CHECK
 954         bool "Sysctl checks"
 955         depends on SYSCTL
 956         ---help---
 957           sys_sysctl uses binary paths that have been found challenging
 958           to properly maintain and use. This enables checks that help
 959           you to keep things correct.
 960
 961 source mm/Kconfig.debug
 962 source kernel/trace/Kconfig
 963
 964 config PROVIDE_OHCI1394_DMA_INIT
 965         bool "Remote debugging over FireWire early on boot"
 966         depends on PCI && X86
 967         help
 968           If you want to debug problems which hang or crash the kernel early
 969           on boot and the crashing machine has a FireWire port, you can use
 970           this feature to remotely access the memory of the crashed machine
 971           over FireWire. This employs remote DMA as part of the OHCI1394
 972           specification which is now the standard for FireWire controllers.
 973
 974           With remote DMA, you can monitor the printk buffer remotely using
 975           firescope and access all memory below 4GB using fireproxy from gdb.
 976           Even controlling a kernel debugger is possible using remote DMA.
 977
 978           Usage:
 979
 980           If ohci1394_dma=early is used as boot parameter, it will initialize
 981           all OHCI1394 controllers which are found in the PCI config space.
 982
 983           As all changes to the FireWire bus such as enabling and disabling
 984           devices cause a bus reset and thereby disable remote DMA for all
 985           devices, be sure to have the cable plugged and FireWire enabled on
 986           the debugging host before booting the debug target for debugging.
 987
 988           This code (~1k) is freed after boot. By then, the firewire stack
 989           in charge of the OHCI-1394 controllers should be used instead.
 990
 991           See Documentation/debugging-via-ohci1394.txt for more information.
 992
 993 config FIREWIRE_OHCI_REMOTE_DMA
 994         bool "Remote debugging over FireWire with firewire-ohci"
 995         depends on FIREWIRE_OHCI
 996         help
 997           This option lets you use the FireWire bus for remote debugging
 998           with help of the firewire-ohci driver. It enables unfiltered
 999           remote DMA in firewire-ohci.
1000           See Documentation/debugging-via-ohci1394.txt for more information.
1001
1002           If unsure, say N.
1003
1004 config BUILD_DOCSRC
1005         bool "Build targets in Documentation/ tree"
1006         depends on HEADERS_CHECK
1007         help
1008           This option attempts to build objects from the source files in the
1009           kernel Documentation/ tree.
1010
1011           Say N if you are unsure.
1012
1013 config DYNAMIC_DEBUG
1014         bool "Enable dynamic printk() support"
1015         default n
1016         depends on PRINTK
1017         depends on DEBUG_FS
1018         help
1019
1020           Compiles debug level messages into the kernel, which would not
1021           otherwise be available at runtime. These messages can then be
1022           enabled/disabled based on various levels of scope - per source file,
1023           function, module, format string, and line number. This mechanism
1024           implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1025           this compile option is a larger kernel text size of about 2%.
1026
1027           Usage:
1028
1029           Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
1030           which is contained in the 'debugfs' filesystem. Thus, the debugfs
1031           filesystem must first be mounted before making use of this feature.
1032           We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
1033           file contains a list of the debug statements that can be enabled. The
1034           format for each line of the file is:
1035
1036                 filename:lineno [module]function flags format
1037
1038           filename : source file of the debug statement
1039           lineno : line number of the debug statement
1040           module : module that contains the debug statement
1041           function : function that contains the debug statement
1042           flags : 'p' means the line is turned 'on' for printing
1043           format : the format used for the debug statement
1044
1045           From a live system:
1046
1047                 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
1048                 # filename:lineno [module]function flags format
1049                 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1050                 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1051                 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1052
1053           Example usage:
1054
1055                 // enable the message at line 1603 of file svcsock.c
1056                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1057                                                 <debugfs>/dynamic_debug/ddebug
1058
1059                 // enable all the messages in file svcsock.c
1060                 nullarbor:~ # echo -n 'file svcsock.c +p' >
1061                                                 <debugfs>/dynamic_debug/ddebug
1062
1063                 // enable all the messages in the NFS server module
1064                 nullarbor:~ # echo -n 'module nfsd +p' >
1065                                                 <debugfs>/dynamic_debug/ddebug
1066
1067                 // enable all 12 messages in the function svc_process()
1068                 nullarbor:~ # echo -n 'func svc_process +p' >
1069                                                 <debugfs>/dynamic_debug/ddebug
1070
1071                 // disable all 12 messages in the function svc_process()
1072                 nullarbor:~ # echo -n 'func svc_process -p' >
1073                                                 <debugfs>/dynamic_debug/ddebug
1074
1075           See Documentation/dynamic-debug-howto.txt for additional information.
1076
1077 config DMA_API_DEBUG
1078         bool "Enable debugging of DMA-API usage"
1079         depends on HAVE_DMA_API_DEBUG
1080         help
1081           Enable this option to debug the use of the DMA API by device drivers.
1082           With this option you will be able to detect common bugs in device
1083           drivers like double-freeing of DMA mappings or freeing mappings that
1084           were never allocated.
1085           This option causes a performance degredation.  Use only if you want
1086           to debug device drivers. If unsure, say N.
1087
1088 source "samples/Kconfig"
1089
1090 source "lib/Kconfig.kgdb"
1091
1092 source "lib/Kconfig.kmemcheck"