lib/Kconfig.debug

   1
   2 config PRINTK_TIME
   3         bool "Show timing information on printks"
   4         depends on PRINTK
   5         help
   6           Selecting this option causes timing information to be
   7           included in printk output.  This allows you to measure
   8           the interval between kernel operations, including bootup
   9           operations.  This is useful for identifying long delays
  10           in kernel startup.
  11
  12 config ENABLE_WARN_DEPRECATED
  13         bool "Enable __deprecated logic"
  14         default y
  15         help
  16           Enable the __deprecated logic in the kernel build.
  17           Disable this to suppress the "warning: 'foo' is deprecated
  18           (declared at kernel/power/somefile.c:1234)" messages.
  19
  20 config ENABLE_MUST_CHECK
  21         bool "Enable __must_check logic"
  22         default y
  23         help
  24           Enable the __must_check logic in the kernel build.  Disable this to
  25           suppress the "warning: ignoring return value of 'foo', declared with
  26           attribute warn_unused_result" messages.
  27
  28 config FRAME_WARN
  29         int "Warn for stack frames larger than (needs gcc 4.4)"
  30         range 0 8192
  31         default 1024 if !64BIT
  32         default 2048 if 64BIT
  33         help
  34           Tell gcc to warn at build time for stack frames larger than this.
  35           Setting this too low will cause a lot of warnings.
  36           Setting it to 0 disables the warning.
  37           Requires gcc 4.4
  38
  39 config MAGIC_SYSRQ
  40         bool "Magic SysRq key"
  41         depends on !UML
  42         help
  43           If you say Y here, you will have some control over the system even
  44           if the system crashes for example during kernel debugging (e.g., you
  45           will be able to flush the buffer cache to disk, reboot the system
  46           immediately or dump some status information). This is accomplished
  47           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  48           also works on a serial console (on PC hardware at least), if you
  49           send a BREAK and then within 5 seconds a command keypress. The
  50           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  51           unless you really know what this hack does.
  52
  53 config UNUSED_SYMBOLS
  54         bool "Enable unused/obsolete exported symbols"
  55         default y if X86
  56         help
  57           Unused but exported symbols make the kernel needlessly bigger.  For
  58           that reason most of these unused exports will soon be removed.  This
  59           option is provided temporarily to provide a transition period in case
  60           some external kernel module needs one of these symbols anyway. If you
  61           encounter such a case in your module, consider if you are actually
  62           using the right API.  (rationale: since nobody in the kernel is using
  63           this in a module, there is a pretty good chance it's actually the
  64           wrong interface to use).  If you really need the symbol, please send a
  65           mail to the linux kernel mailing list mentioning the symbol and why
  66           you really need it, and what the merge plan to the mainline kernel for
  67           your module is.
  68
  69 config DEBUG_FS
  70         bool "Debug Filesystem"
  71         depends on SYSFS
  72         help
  73           debugfs is a virtual file system that kernel developers use to put
  74           debugging files into.  Enable this option to be able to read and
  75           write to these files.
  76
  77           For detailed documentation on the debugfs API, see
  78           Documentation/DocBook/filesystems.
  79
  80           If unsure, say N.
  81
  82 config HEADERS_CHECK
  83         bool "Run 'make headers_check' when building vmlinux"
  84         depends on !UML
  85         help
  86           This option will extract the user-visible kernel headers whenever
  87           building the kernel, and will run basic sanity checks on them to
  88           ensure that exported files do not attempt to include files which
  89           were not exported, etc.
  90
  91           If you're making modifications to header files which are
  92           relevant for userspace, say 'Y', and check the headers
  93           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  94           your build tree), to make sure they're suitable.
  95
  96 config DEBUG_SECTION_MISMATCH
  97         bool "Enable full Section mismatch analysis"
  98         depends on UNDEFINED
  99         # This option is on purpose disabled for now.
 100         # It will be enabled when we are down to a resonable number
 101         # of section mismatch warnings (< 10 for an allyesconfig build)
 102         help
 103           The section mismatch analysis checks if there are illegal
 104           references from one section to another section.
 105           Linux will during link or during runtime drop some sections
 106           and any use of code/data previously in these sections will
 107           most likely result in an oops.
 108           In the code functions and variables are annotated with
 109           __init, __devinit etc. (see full list in include/linux/init.h)
 110           which results in the code/data being placed in specific sections.
 111           The section mismatch analysis is always done after a full
 112           kernel build but enabling this option will in addition
 113           do the following:
 114           - Add the option -fno-inline-functions-called-once to gcc
 115             When inlining a function annotated __init in a non-init
 116             function we would lose the section information and thus
 117             the analysis would not catch the illegal reference.
 118             This option tells gcc to inline less but will also
 119             result in a larger kernel.
 120           - Run the section mismatch analysis for each module/built-in.o
 121             When we run the section mismatch analysis on vmlinux.o we
 122             lose valueble information about where the mismatch was
 123             introduced.
 124             Running the analysis for each module/built-in.o file
 125             will tell where the mismatch happens much closer to the
 126             source. The drawback is that we will report the same
 127             mismatch at least twice.
 128           - Enable verbose reporting from modpost to help solving
 129             the section mismatches reported.
 130
 131 config DEBUG_KERNEL
 132         bool "Kernel debugging"
 133         help
 134           Say Y here if you are developing drivers or trying to debug and
 135           identify kernel problems.
 136
 137 config DEBUG_SHIRQ
 138         bool "Debug shared IRQ handlers"
 139         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 140         help
 141           Enable this to generate a spurious interrupt as soon as a shared
 142           interrupt handler is registered, and just before one is deregistered.
 143           Drivers ought to be able to handle interrupts coming in at those
 144           points; some don't and need to be caught.
 145
 146 config DETECT_SOFTLOCKUP
 147         bool "Detect Soft Lockups"
 148         depends on DEBUG_KERNEL && !S390
 149         default y
 150         help
 151           Say Y here to enable the kernel to detect "soft lockups",
 152           which are bugs that cause the kernel to loop in kernel
 153           mode for more than 60 seconds, without giving other tasks a
 154           chance to run.
 155
 156           When a soft-lockup is detected, the kernel will print the
 157           current stack trace (which you should report), but the
 158           system will stay locked up. This feature has negligible
 159           overhead.
 160
 161           (Note that "hard lockups" are separate type of bugs that
 162            can be detected via the NMI-watchdog, on platforms that
 163            support it.)
 164
 165 config BOOTPARAM_SOFTLOCKUP_PANIC
 166         bool "Panic (Reboot) On Soft Lockups"
 167         depends on DETECT_SOFTLOCKUP
 168         help
 169           Say Y here to enable the kernel to panic on "soft lockups",
 170           which are bugs that cause the kernel to loop in kernel
 171           mode for more than 60 seconds, without giving other tasks a
 172           chance to run.
 173
 174           The panic can be used in combination with panic_timeout,
 175           to cause the system to reboot automatically after a
 176           lockup has been detected. This feature is useful for
 177           high-availability systems that have uptime guarantees and
 178           where a lockup must be resolved ASAP.
 179
 180           Say N if unsure.
 181
 182 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 183         int
 184         depends on DETECT_SOFTLOCKUP
 185         range 0 1
 186         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 187         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 188
 189 config SCHED_DEBUG
 190         bool "Collect scheduler debugging info"
 191         depends on DEBUG_KERNEL && PROC_FS
 192         default y
 193         help
 194           If you say Y here, the /proc/sched_debug file will be provided
 195           that can help debug the scheduler. The runtime overhead of this
 196           option is minimal.
 197
 198 config SCHEDSTATS
 199         bool "Collect scheduler statistics"
 200         depends on DEBUG_KERNEL && PROC_FS
 201         help
 202           If you say Y here, additional code will be inserted into the
 203           scheduler and related routines to collect statistics about
 204           scheduler behavior and provide them in /proc/schedstat.  These
 205           stats may be useful for both tuning and debugging the scheduler
 206           If you aren't debugging the scheduler or trying to tune a specific
 207           application, you can say N to avoid the very slight overhead
 208           this adds.
 209
 210 config TIMER_STATS
 211         bool "Collect kernel timers statistics"
 212         depends on DEBUG_KERNEL && PROC_FS
 213         help
 214           If you say Y here, additional code will be inserted into the
 215           timer routines to collect statistics about kernel timers being
 216           reprogrammed. The statistics can be read from /proc/timer_stats.
 217           The statistics collection is started by writing 1 to /proc/timer_stats,
 218           writing 0 stops it. This feature is useful to collect information
 219           about timer usage patterns in kernel and userspace. This feature
 220           is lightweight if enabled in the kernel config but not activated
 221           (it defaults to deactivated on bootup and will only be activated
 222           if some application like powertop activates it explicitly).
 223
 224 config DEBUG_OBJECTS
 225         bool "Debug object operations"
 226         depends on DEBUG_KERNEL
 227         help
 228           If you say Y here, additional code will be inserted into the
 229           kernel to track the life time of various objects and validate
 230           the operations on those objects.
 231
 232 config DEBUG_OBJECTS_SELFTEST
 233         bool "Debug objects selftest"
 234         depends on DEBUG_OBJECTS
 235         help
 236           This enables the selftest of the object debug code.
 237
 238 config DEBUG_OBJECTS_FREE
 239         bool "Debug objects in freed memory"
 240         depends on DEBUG_OBJECTS
 241         help
 242           This enables checks whether a k/v free operation frees an area
 243           which contains an object which has not been deactivated
 244           properly. This can make kmalloc/kfree-intensive workloads
 245           much slower.
 246
 247 config DEBUG_OBJECTS_TIMERS
 248         bool "Debug timer objects"
 249         depends on DEBUG_OBJECTS
 250         help
 251           If you say Y here, additional code will be inserted into the
 252           timer routines to track the life time of timer objects and
 253           validate the timer operations.
 254
 255 config DEBUG_SLAB
 256         bool "Debug slab memory allocations"
 257         depends on DEBUG_KERNEL && SLAB
 258         help
 259           Say Y here to have the kernel do limited verification on memory
 260           allocation as well as poisoning memory on free to catch use of freed
 261           memory. This can make kmalloc/kfree-intensive workloads much slower.
 262
 263 config DEBUG_SLAB_LEAK
 264         bool "Memory leak debugging"
 265         depends on DEBUG_SLAB
 266
 267 config SLUB_DEBUG_ON
 268         bool "SLUB debugging on by default"
 269         depends on SLUB && SLUB_DEBUG
 270         default n
 271         help
 272           Boot with debugging on by default. SLUB boots by default with
 273           the runtime debug capabilities switched off. Enabling this is
 274           equivalent to specifying the "slub_debug" parameter on boot.
 275           There is no support for more fine grained debug control like
 276           possible with slub_debug=xxx. SLUB debugging may be switched
 277           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 278           "slub_debug=-".
 279
 280 config SLUB_STATS
 281         default n
 282         bool "Enable SLUB performance statistics"
 283         depends on SLUB && SLUB_DEBUG && SYSFS
 284         help
 285           SLUB statistics are useful to debug SLUBs allocation behavior in
 286           order find ways to optimize the allocator. This should never be
 287           enabled for production use since keeping statistics slows down
 288           the allocator by a few percentage points. The slabinfo command
 289           supports the determination of the most active slabs to figure
 290           out which slabs are relevant to a particular load.
 291           Try running: slabinfo -DA
 292
 293 config DEBUG_PREEMPT
 294         bool "Debug preemptible kernel"
 295         depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
 296         default y
 297         help
 298           If you say Y here then the kernel will use a debug variant of the
 299           commonly used smp_processor_id() function and will print warnings
 300           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 301           will detect preemption count underflows.
 302
 303 config DEBUG_RT_MUTEXES
 304         bool "RT Mutex debugging, deadlock detection"
 305         depends on DEBUG_KERNEL && RT_MUTEXES
 306         help
 307          This allows rt mutex semantics violations and rt mutex related
 308          deadlocks (lockups) to be detected and reported automatically.
 309
 310 config DEBUG_PI_LIST
 311         bool
 312         default y
 313         depends on DEBUG_RT_MUTEXES
 314
 315 config RT_MUTEX_TESTER
 316         bool "Built-in scriptable tester for rt-mutexes"
 317         depends on DEBUG_KERNEL && RT_MUTEXES
 318         help
 319           This option enables a rt-mutex tester.
 320
 321 config DEBUG_SPINLOCK
 322         bool "Spinlock and rw-lock debugging: basic checks"
 323         depends on DEBUG_KERNEL
 324         help
 325           Say Y here and build SMP to catch missing spinlock initialization
 326           and certain other kinds of spinlock errors commonly made.  This is
 327           best used in conjunction with the NMI watchdog so that spinlock
 328           deadlocks are also debuggable.
 329
 330 config DEBUG_MUTEXES
 331         bool "Mutex debugging: basic checks"
 332         depends on DEBUG_KERNEL
 333         help
 334          This feature allows mutex semantics violations to be detected and
 335          reported.
 336
 337 config DEBUG_LOCK_ALLOC
 338         bool "Lock debugging: detect incorrect freeing of live locks"
 339         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 340         select DEBUG_SPINLOCK
 341         select DEBUG_MUTEXES
 342         select LOCKDEP
 343         help
 344          This feature will check whether any held lock (spinlock, rwlock,
 345          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 346          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 347          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 348          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 349          held during task exit.
 350
 351 config PROVE_LOCKING
 352         bool "Lock debugging: prove locking correctness"
 353         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 354         select LOCKDEP
 355         select DEBUG_SPINLOCK
 356         select DEBUG_MUTEXES
 357         select DEBUG_LOCK_ALLOC
 358         default n
 359         help
 360          This feature enables the kernel to prove that all locking
 361          that occurs in the kernel runtime is mathematically
 362          correct: that under no circumstance could an arbitrary (and
 363          not yet triggered) combination of observed locking
 364          sequences (on an arbitrary number of CPUs, running an
 365          arbitrary number of tasks and interrupt contexts) cause a
 366          deadlock.
 367
 368          In short, this feature enables the kernel to report locking
 369          related deadlocks before they actually occur.
 370
 371          The proof does not depend on how hard and complex a
 372          deadlock scenario would be to trigger: how many
 373          participant CPUs, tasks and irq-contexts would be needed
 374          for it to trigger. The proof also does not depend on
 375          timing: if a race and a resulting deadlock is possible
 376          theoretically (no matter how unlikely the race scenario
 377          is), it will be proven so and will immediately be
 378          reported by the kernel (once the event is observed that
 379          makes the deadlock theoretically possible).
 380
 381          If a deadlock is impossible (i.e. the locking rules, as
 382          observed by the kernel, are mathematically correct), the
 383          kernel reports nothing.
 384
 385          NOTE: this feature can also be enabled for rwlocks, mutexes
 386          and rwsems - in which case all dependencies between these
 387          different locking variants are observed and mapped too, and
 388          the proof of observed correctness is also maintained for an
 389          arbitrary combination of these separate locking variants.
 390
 391          For more details, see Documentation/lockdep-design.txt.
 392
 393 config LOCKDEP
 394         bool
 395         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 396         select STACKTRACE
 397         select FRAME_POINTER if !X86 && !MIPS && !PPC
 398         select KALLSYMS
 399         select KALLSYMS_ALL
 400
 401 config LOCK_STAT
 402         bool "Lock usage statistics"
 403         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 404         select LOCKDEP
 405         select DEBUG_SPINLOCK
 406         select DEBUG_MUTEXES
 407         select DEBUG_LOCK_ALLOC
 408         default n
 409         help
 410          This feature enables tracking lock contention points
 411
 412          For more details, see Documentation/lockstat.txt
 413
 414 config DEBUG_LOCKDEP
 415         bool "Lock dependency engine debugging"
 416         depends on DEBUG_KERNEL && LOCKDEP
 417         help
 418           If you say Y here, the lock dependency engine will do
 419           additional runtime checks to debug itself, at the price
 420           of more runtime overhead.
 421
 422 config TRACE_IRQFLAGS
 423         depends on DEBUG_KERNEL
 424         bool
 425         default y
 426         depends on TRACE_IRQFLAGS_SUPPORT
 427         depends on PROVE_LOCKING
 428
 429 config DEBUG_SPINLOCK_SLEEP
 430         bool "Spinlock debugging: sleep-inside-spinlock checking"
 431         depends on DEBUG_KERNEL
 432         help
 433           If you say Y here, various routines which may sleep will become very
 434           noisy if they are called with a spinlock held.
 435
 436 config DEBUG_LOCKING_API_SELFTESTS
 437         bool "Locking API boot-time self-tests"
 438         depends on DEBUG_KERNEL
 439         help
 440           Say Y here if you want the kernel to run a short self-test during
 441           bootup. The self-test checks whether common types of locking bugs
 442           are detected by debugging mechanisms or not. (if you disable
 443           lock debugging then those bugs wont be detected of course.)
 444           The following locking APIs are covered: spinlocks, rwlocks,
 445           mutexes and rwsems.
 446
 447 config STACKTRACE
 448         bool
 449         depends on STACKTRACE_SUPPORT
 450
 451 config DEBUG_KOBJECT
 452         bool "kobject debugging"
 453         depends on DEBUG_KERNEL
 454         help
 455           If you say Y here, some extra kobject debugging messages will be sent
 456           to the syslog.
 457
 458 config DEBUG_HIGHMEM
 459         bool "Highmem debugging"
 460         depends on DEBUG_KERNEL && HIGHMEM
 461         help
 462           This options enables addition error checking for high memory systems.
 463           Disable for production systems.
 464
 465 config DEBUG_BUGVERBOSE
 466         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 467         depends on BUG
 468         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 469                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 470         default !EMBEDDED
 471         help
 472           Say Y here to make BUG() panics output the file name and line number
 473           of the BUG call as well as the EIP and oops trace.  This aids
 474           debugging but costs about 70-100K of memory.
 475
 476 config DEBUG_INFO
 477         bool "Compile the kernel with debug info"
 478         depends on DEBUG_KERNEL
 479         help
 480           If you say Y here the resulting kernel image will include
 481           debugging info resulting in a larger kernel image.
 482           This adds debug symbols to the kernel and modules (gcc -g), and
 483           is needed if you intend to use kernel crashdump or binary object
 484           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 485           Say Y here only if you plan to debug the kernel.
 486
 487           If unsure, say N.
 488
 489 config DEBUG_VM
 490         bool "Debug VM"
 491         depends on DEBUG_KERNEL
 492         help
 493           Enable this to turn on extended checks in the virtual-memory system
 494           that may impact performance.
 495
 496           If unsure, say N.
 497
 498 config DEBUG_VIRTUAL
 499         bool "Debug VM translations"
 500         depends on DEBUG_KERNEL && X86
 501         help
 502           Enable some costly sanity checks in virtual to page code. This can
 503           catch mistakes with virt_to_page() and friends.
 504
 505           If unsure, say N.
 506
 507 config DEBUG_WRITECOUNT
 508         bool "Debug filesystem writers count"
 509         depends on DEBUG_KERNEL
 510         help
 511           Enable this to catch wrong use of the writers count in struct
 512           vfsmount.  This will increase the size of each file struct by
 513           32 bits.
 514
 515           If unsure, say N.
 516
 517 config DEBUG_MEMORY_INIT
 518         bool "Debug memory initialisation" if EMBEDDED
 519         default !EMBEDDED
 520         help
 521           Enable this for additional checks during memory initialisation.
 522           The sanity checks verify aspects of the VM such as the memory model
 523           and other information provided by the architecture. Verbose
 524           information will be printed at KERN_DEBUG loglevel depending
 525           on the mminit_loglevel= command-line option.
 526
 527           If unsure, say Y
 528
 529 config DEBUG_LIST
 530         bool "Debug linked list manipulation"
 531         depends on DEBUG_KERNEL
 532         help
 533           Enable this to turn on extended checks in the linked-list
 534           walking routines.
 535
 536           If unsure, say N.
 537
 538 config DEBUG_SG
 539         bool "Debug SG table operations"
 540         depends on DEBUG_KERNEL
 541         help
 542           Enable this to turn on checks on scatter-gather tables. This can
 543           help find problems with drivers that do not properly initialize
 544           their sg tables.
 545
 546           If unsure, say N.
 547
 548 config FRAME_POINTER
 549         bool "Compile the kernel with frame pointers"
 550         depends on DEBUG_KERNEL && \
 551                 (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \
 552                  AVR32 || SUPERH || BLACKFIN || MN10300)
 553         default y if DEBUG_INFO && UML
 554         help
 555           If you say Y here the resulting kernel image will be slightly larger
 556           and slower, but it might give very useful debugging information on
 557           some architectures or if you use external debuggers.
 558           If you don't debug the kernel, you can say N.
 559
 560 config BOOT_PRINTK_DELAY
 561         bool "Delay each boot printk message by N milliseconds"
 562         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 563         help
 564           This build option allows you to read kernel boot messages
 565           by inserting a short delay after each one.  The delay is
 566           specified in milliseconds on the kernel command line,
 567           using "boot_delay=N".
 568
 569           It is likely that you would also need to use "lpj=M" to preset
 570           the "loops per jiffie" value.
 571           See a previous boot log for the "lpj" value to use for your
 572           system, and then set "lpj=M" before setting "boot_delay=N".
 573           NOTE:  Using this option may adversely affect SMP systems.
 574           I.e., processors other than the first one may not boot up.
 575           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 576           what it believes to be lockup conditions.
 577
 578 config RCU_TORTURE_TEST
 579         tristate "torture tests for RCU"
 580         depends on DEBUG_KERNEL
 581         default n
 582         help
 583           This option provides a kernel module that runs torture tests
 584           on the RCU infrastructure.  The kernel module may be built
 585           after the fact on the running kernel to be tested, if desired.
 586
 587           Say Y here if you want RCU torture tests to be built into
 588           the kernel.
 589           Say M if you want the RCU torture tests to build as a module.
 590           Say N if you are unsure.
 591
 592 config RCU_TORTURE_TEST_RUNNABLE
 593         bool "torture tests for RCU runnable by default"
 594         depends on RCU_TORTURE_TEST = y
 595         default n
 596         help
 597           This option provides a way to build the RCU torture tests
 598           directly into the kernel without them starting up at boot
 599           time.  You can use /proc/sys/kernel/rcutorture_runnable
 600           to manually override this setting.  This /proc file is
 601           available only when the RCU torture tests have been built
 602           into the kernel.
 603
 604           Say Y here if you want the RCU torture tests to start during
 605           boot (you probably don't).
 606           Say N here if you want the RCU torture tests to start only
 607           after being manually enabled via /proc.
 608
 609 config RCU_CPU_STALL_DETECTOR
 610         bool "Check for stalled CPUs delaying RCU grace periods"
 611         depends on CLASSIC_RCU
 612         default n
 613         help
 614           This option causes RCU to printk information on which
 615           CPUs are delaying the current grace period, but only when
 616           the grace period extends for excessive time periods.
 617
 618           Say Y if you want RCU to perform such checks.
 619
 620           Say N if you are unsure.
 621
 622 config KPROBES_SANITY_TEST
 623         bool "Kprobes sanity tests"
 624         depends on DEBUG_KERNEL
 625         depends on KPROBES
 626         default n
 627         help
 628           This option provides for testing basic kprobes functionality on
 629           boot. A sample kprobe, jprobe and kretprobe are inserted and
 630           verified for functionality.
 631
 632           Say N if you are unsure.
 633
 634 config BACKTRACE_SELF_TEST
 635         tristate "Self test for the backtrace code"
 636         depends on DEBUG_KERNEL
 637         default n
 638         help
 639           This option provides a kernel module that can be used to test
 640           the kernel stack backtrace code. This option is not useful
 641           for distributions or general kernels, but only for kernel
 642           developers working on architecture code.
 643
 644           Note that if you want to also test saved backtraces, you will
 645           have to enable STACKTRACE as well.
 646
 647           Say N if you are unsure.
 648
 649 config DEBUG_BLOCK_EXT_DEVT
 650         bool "Force extended block device numbers and spread them"
 651         depends on DEBUG_KERNEL
 652         depends on BLOCK
 653         default n
 654         help
 655           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 656           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 657           YOU ARE DOING.  Distros, please enable this and fix whatever
 658           is broken.
 659
 660           Conventionally, block device numbers are allocated from
 661           predetermined contiguous area.  However, extended block area
 662           may introduce non-contiguous block device numbers.  This
 663           option forces most block device numbers to be allocated from
 664           the extended space and spreads them to discover kernel or
 665           userland code paths which assume predetermined contiguous
 666           device number allocation.
 667
 668           Note that turning on this debug option shuffles all the
 669           device numbers for all IDE and SCSI devices including libata
 670           ones, so root partition specified using device number
 671           directly (via rdev or root=MAJ:MIN) won't work anymore.
 672           Textual device names (root=/dev/sdXn) will continue to work.
 673
 674           Say N if you are unsure.
 675
 676 config LKDTM
 677         tristate "Linux Kernel Dump Test Tool Module"
 678         depends on DEBUG_KERNEL
 679         depends on KPROBES
 680         depends on BLOCK
 681         default n
 682         help
 683         This module enables testing of the different dumping mechanisms by
 684         inducing system failures at predefined crash points.
 685         If you don't need it: say N
 686         Choose M here to compile this code as a module. The module will be
 687         called lkdtm.
 688
 689         Documentation on how to use the module can be found in
 690         drivers/misc/lkdtm.c
 691
 692 config FAULT_INJECTION
 693         bool "Fault-injection framework"
 694         depends on DEBUG_KERNEL
 695         help
 696           Provide fault-injection framework.
 697           For more details, see Documentation/fault-injection/.
 698
 699 config FAILSLAB
 700         bool "Fault-injection capability for kmalloc"
 701         depends on FAULT_INJECTION
 702         help
 703           Provide fault-injection capability for kmalloc.
 704
 705 config FAIL_PAGE_ALLOC
 706         bool "Fault-injection capabilitiy for alloc_pages()"
 707         depends on FAULT_INJECTION
 708         help
 709           Provide fault-injection capability for alloc_pages().
 710
 711 config FAIL_MAKE_REQUEST
 712         bool "Fault-injection capability for disk IO"
 713         depends on FAULT_INJECTION && BLOCK
 714         help
 715           Provide fault-injection capability for disk IO.
 716
 717 config FAIL_IO_TIMEOUT
 718         bool "Faul-injection capability for faking disk interrupts"
 719         depends on FAULT_INJECTION && BLOCK
 720         help
 721           Provide fault-injection capability on end IO handling. This
 722           will make the block layer "forget" an interrupt as configured,
 723           thus exercising the error handling.
 724
 725           Only works with drivers that use the generic timeout handling,
 726           for others it wont do anything.
 727
 728 config FAULT_INJECTION_DEBUG_FS
 729         bool "Debugfs entries for fault-injection capabilities"
 730         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 731         help
 732           Enable configuration of fault-injection capabilities via debugfs.
 733
 734 config FAULT_INJECTION_STACKTRACE_FILTER
 735         bool "stacktrace filter for fault-injection capabilities"
 736         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 737         depends on !X86_64
 738         select STACKTRACE
 739         select FRAME_POINTER if !PPC
 740         help
 741           Provide stacktrace filter for fault-injection capabilities
 742
 743 config LATENCYTOP
 744         bool "Latency measuring infrastructure"
 745         select FRAME_POINTER if !MIPS && !PPC
 746         select KALLSYMS
 747         select KALLSYMS_ALL
 748         select STACKTRACE
 749         select SCHEDSTATS
 750         select SCHED_DEBUG
 751         depends on HAVE_LATENCYTOP_SUPPORT
 752         help
 753           Enable this option if you want to use the LatencyTOP tool
 754           to find out which userspace is blocking on what kernel operations.
 755
 756 config SYSCTL_SYSCALL_CHECK
 757         bool "Sysctl checks"
 758         depends on SYSCTL_SYSCALL
 759         ---help---
 760           sys_sysctl uses binary paths that have been found challenging
 761           to properly maintain and use. This enables checks that help
 762           you to keep things correct.
 763
 764 source kernel/trace/Kconfig
 765
 766 config PROVIDE_OHCI1394_DMA_INIT
 767         bool "Remote debugging over FireWire early on boot"
 768         depends on PCI && X86
 769         help
 770           If you want to debug problems which hang or crash the kernel early
 771           on boot and the crashing machine has a FireWire port, you can use
 772           this feature to remotely access the memory of the crashed machine
 773           over FireWire. This employs remote DMA as part of the OHCI1394
 774           specification which is now the standard for FireWire controllers.
 775
 776           With remote DMA, you can monitor the printk buffer remotely using
 777           firescope and access all memory below 4GB using fireproxy from gdb.
 778           Even controlling a kernel debugger is possible using remote DMA.
 779
 780           Usage:
 781
 782           If ohci1394_dma=early is used as boot parameter, it will initialize
 783           all OHCI1394 controllers which are found in the PCI config space.
 784
 785           As all changes to the FireWire bus such as enabling and disabling
 786           devices cause a bus reset and thereby disable remote DMA for all
 787           devices, be sure to have the cable plugged and FireWire enabled on
 788           the debugging host before booting the debug target for debugging.
 789
 790           This code (~1k) is freed after boot. By then, the firewire stack
 791           in charge of the OHCI-1394 controllers should be used instead.
 792
 793           See Documentation/debugging-via-ohci1394.txt for more information.
 794
 795 config FIREWIRE_OHCI_REMOTE_DMA
 796         bool "Remote debugging over FireWire with firewire-ohci"
 797         depends on FIREWIRE_OHCI
 798         help
 799           This option lets you use the FireWire bus for remote debugging
 800           with help of the firewire-ohci driver. It enables unfiltered
 801           remote DMA in firewire-ohci.
 802           See Documentation/debugging-via-ohci1394.txt for more information.
 803
 804           If unsure, say N.
 805
 806 config KMEMTRACE
 807         bool "Kernel memory tracer (kmemtrace)"
 808         depends on RELAY && DEBUG_FS && MARKERS
 809         help
 810           kmemtrace provides tracing for slab allocator functions, such as
 811           kmalloc, kfree, kmem_cache_alloc, kmem_cache_free etc.. Collected
 812           data is then fed to the userspace application in order to analyse
 813           allocation hotspots, internal fragmentation and so on, making it
 814           possible to see how well an allocator performs, as well as debug
 815           and profile kernel code.
 816
 817           This requires an userspace application to use. See
 818           Documentation/vm/kmemtrace.txt for more information.
 819
 820           Saying Y will make the kernel somewhat larger and slower. However,
 821           if you disable kmemtrace at run-time or boot-time, the performance
 822           impact is minimal (depending on the arch the kernel is built for).
 823
 824           If unsure, say N.
 825
 826 config KMEMTRACE_DEFAULT_ENABLED
 827         bool "Enabled by default at boot"
 828         depends on KMEMTRACE
 829         help
 830           Say Y here to enable kmemtrace at boot-time by default. Whatever
 831           the choice, the behavior can be overridden by a kernel parameter,
 832           as described in documentation.
 833
 834 menuconfig BUILD_DOCSRC
 835         bool "Build targets in Documentation/ tree"
 836         depends on HEADERS_CHECK
 837         help
 838           This option attempts to build objects from the source files in the
 839           kernel Documentation/ tree.
 840
 841           Say N if you are unsure.
 842
 843 config DYNAMIC_PRINTK_DEBUG
 844         bool "Enable dynamic printk() call support"
 845         default n
 846         depends on PRINTK
 847         select PRINTK_DEBUG
 848         help
 849
 850           Compiles debug level messages into the kernel, which would not
 851           otherwise be available at runtime. These messages can then be
 852           enabled/disabled on a per module basis. This mechanism implicitly
 853           enables all pr_debug() and dev_dbg() calls. The impact of this
 854           compile option is a larger kernel text size of about 2%.
 855
 856           Usage:
 857
 858           Dynamic debugging is controlled by the debugfs file,
 859           dynamic_printk/modules. This file contains a list of the modules that
 860           can be enabled. The format of the file is the module name, followed
 861           by a set of flags that can be enabled. The first flag is always the
 862           'enabled' flag. For example:
 863
 864                 <module_name> <enabled=0/1>
 865                                 .
 866                                 .
 867                                 .
 868
 869           <module_name> : Name of the module in which the debug call resides
 870           <enabled=0/1> : whether the messages are enabled or not
 871
 872           From a live system:
 873
 874                 snd_hda_intel enabled=0
 875                 fixup enabled=0
 876                 driver enabled=0
 877
 878           Enable a module:
 879
 880                 $echo "set enabled=1 <module_name>" > dynamic_printk/modules
 881
 882           Disable a module:
 883
 884                 $echo "set enabled=0 <module_name>" > dynamic_printk/modules
 885
 886           Enable all modules:
 887
 888                 $echo "set enabled=1 all" > dynamic_printk/modules
 889
 890           Disable all modules:
 891
 892                 $echo "set enabled=0 all" > dynamic_printk/modules
 893
 894           Finally, passing "dynamic_printk" at the command line enables
 895           debugging for all modules. This mode can be turned off via the above
 896           disable command.
 897
 898 source "samples/Kconfig"
 899
 900 source "lib/Kconfig.kgdb"