lib/Kconfig.debug

   1
   2 config PRINTK_TIME
   3         bool "Show timing information on printks"
   4         depends on PRINTK
   5         help
   6           Selecting this option causes timing information to be
   7           included in printk output.  This allows you to measure
   8           the interval between kernel operations, including bootup
   9           operations.  This is useful for identifying long delays
  10           in kernel startup.
  11
  12 config ENABLE_WARN_DEPRECATED
  13         bool "Enable __deprecated logic"
  14         default y
  15         help
  16           Enable the __deprecated logic in the kernel build.
  17           Disable this to suppress the "warning: 'foo' is deprecated
  18           (declared at kernel/power/somefile.c:1234)" messages.
  19
  20 config ENABLE_MUST_CHECK
  21         bool "Enable __must_check logic"
  22         default y
  23         help
  24           Enable the __must_check logic in the kernel build.  Disable this to
  25           suppress the "warning: ignoring return value of 'foo', declared with
  26           attribute warn_unused_result" messages.
  27
  28 config FRAME_WARN
  29         int "Warn for stack frames larger than (needs gcc 4.4)"
  30         range 0 8192
  31         default 1024 if !64BIT
  32         default 2048 if 64BIT
  33         help
  34           Tell gcc to warn at build time for stack frames larger than this.
  35           Setting this too low will cause a lot of warnings.
  36           Setting it to 0 disables the warning.
  37           Requires gcc 4.4
  38
  39 config MAGIC_SYSRQ
  40         bool "Magic SysRq key"
  41         depends on !UML
  42         help
  43           If you say Y here, you will have some control over the system even
  44           if the system crashes for example during kernel debugging (e.g., you
  45           will be able to flush the buffer cache to disk, reboot the system
  46           immediately or dump some status information). This is accomplished
  47           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  48           also works on a serial console (on PC hardware at least), if you
  49           send a BREAK and then within 5 seconds a command keypress. The
  50           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  51           unless you really know what this hack does.
  52
  53 config UNUSED_SYMBOLS
  54         bool "Enable unused/obsolete exported symbols"
  55         default y if X86
  56         help
  57           Unused but exported symbols make the kernel needlessly bigger.  For
  58           that reason most of these unused exports will soon be removed.  This
  59           option is provided temporarily to provide a transition period in case
  60           some external kernel module needs one of these symbols anyway. If you
  61           encounter such a case in your module, consider if you are actually
  62           using the right API.  (rationale: since nobody in the kernel is using
  63           this in a module, there is a pretty good chance it's actually the
  64           wrong interface to use).  If you really need the symbol, please send a
  65           mail to the linux kernel mailing list mentioning the symbol and why
  66           you really need it, and what the merge plan to the mainline kernel for
  67           your module is.
  68
  69 config DEBUG_FS
  70         bool "Debug Filesystem"
  71         depends on SYSFS
  72         help
  73           debugfs is a virtual file system that kernel developers use to put
  74           debugging files into.  Enable this option to be able to read and
  75           write to these files.
  76
  77           For detailed documentation on the debugfs API, see
  78           Documentation/DocBook/filesystems.
  79
  80           If unsure, say N.
  81
  82 config HEADERS_CHECK
  83         bool "Run 'make headers_check' when building vmlinux"
  84         depends on !UML
  85         help
  86           This option will extract the user-visible kernel headers whenever
  87           building the kernel, and will run basic sanity checks on them to
  88           ensure that exported files do not attempt to include files which
  89           were not exported, etc.
  90
  91           If you're making modifications to header files which are
  92           relevant for userspace, say 'Y', and check the headers
  93           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  94           your build tree), to make sure they're suitable.
  95
  96 config DEBUG_SECTION_MISMATCH
  97         bool "Enable full Section mismatch analysis"
  98         depends on UNDEFINED
  99         # This option is on purpose disabled for now.
 100         # It will be enabled when we are down to a resonable number
 101         # of section mismatch warnings (< 10 for an allyesconfig build)
 102         help
 103           The section mismatch analysis checks if there are illegal
 104           references from one section to another section.
 105           Linux will during link or during runtime drop some sections
 106           and any use of code/data previously in these sections will
 107           most likely result in an oops.
 108           In the code functions and variables are annotated with
 109           __init, __devinit etc. (see full list in include/linux/init.h)
 110           which results in the code/data being placed in specific sections.
 111           The section mismatch analysis is always done after a full
 112           kernel build but enabling this option will in addition
 113           do the following:
 114           - Add the option -fno-inline-functions-called-once to gcc
 115             When inlining a function annotated __init in a non-init
 116             function we would lose the section information and thus
 117             the analysis would not catch the illegal reference.
 118             This option tells gcc to inline less but will also
 119             result in a larger kernel.
 120           - Run the section mismatch analysis for each module/built-in.o
 121             When we run the section mismatch analysis on vmlinux.o we
 122             lose valueble information about where the mismatch was
 123             introduced.
 124             Running the analysis for each module/built-in.o file
 125             will tell where the mismatch happens much closer to the
 126             source. The drawback is that we will report the same
 127             mismatch at least twice.
 128           - Enable verbose reporting from modpost to help solving
 129             the section mismatches reported.
 130
 131 config DEBUG_KERNEL
 132         bool "Kernel debugging"
 133         help
 134           Say Y here if you are developing drivers or trying to debug and
 135           identify kernel problems.
 136
 137 config DEBUG_SHIRQ
 138         bool "Debug shared IRQ handlers"
 139         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 140         help
 141           Enable this to generate a spurious interrupt as soon as a shared
 142           interrupt handler is registered, and just before one is deregistered.
 143           Drivers ought to be able to handle interrupts coming in at those
 144           points; some don't and need to be caught.
 145
 146 config DETECT_SOFTLOCKUP
 147         bool "Detect Soft Lockups"
 148         depends on DEBUG_KERNEL && !S390
 149         default y
 150         help
 151           Say Y here to enable the kernel to detect "soft lockups",
 152           which are bugs that cause the kernel to loop in kernel
 153           mode for more than 60 seconds, without giving other tasks a
 154           chance to run.
 155
 156           When a soft-lockup is detected, the kernel will print the
 157           current stack trace (which you should report), but the
 158           system will stay locked up. This feature has negligible
 159           overhead.
 160
 161           (Note that "hard lockups" are separate type of bugs that
 162            can be detected via the NMI-watchdog, on platforms that
 163            support it.)
 164
 165 config BOOTPARAM_SOFTLOCKUP_PANIC
 166         bool "Panic (Reboot) On Soft Lockups"
 167         depends on DETECT_SOFTLOCKUP
 168         help
 169           Say Y here to enable the kernel to panic on "soft lockups",
 170           which are bugs that cause the kernel to loop in kernel
 171           mode for more than 60 seconds, without giving other tasks a
 172           chance to run.
 173
 174           The panic can be used in combination with panic_timeout,
 175           to cause the system to reboot automatically after a
 176           lockup has been detected. This feature is useful for
 177           high-availability systems that have uptime guarantees and
 178           where a lockup must be resolved ASAP.
 179
 180           Say N if unsure.
 181
 182 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 183         int
 184         depends on DETECT_SOFTLOCKUP
 185         range 0 1
 186         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 187         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 188
 189 config SCHED_DEBUG
 190         bool "Collect scheduler debugging info"
 191         depends on DEBUG_KERNEL && PROC_FS
 192         default y
 193         help
 194           If you say Y here, the /proc/sched_debug file will be provided
 195           that can help debug the scheduler. The runtime overhead of this
 196           option is minimal.
 197
 198 config SCHEDSTATS
 199         bool "Collect scheduler statistics"
 200         depends on DEBUG_KERNEL && PROC_FS
 201         help
 202           If you say Y here, additional code will be inserted into the
 203           scheduler and related routines to collect statistics about
 204           scheduler behavior and provide them in /proc/schedstat.  These
 205           stats may be useful for both tuning and debugging the scheduler
 206           If you aren't debugging the scheduler or trying to tune a specific
 207           application, you can say N to avoid the very slight overhead
 208           this adds.
 209
 210 config TIMER_STATS
 211         bool "Collect kernel timers statistics"
 212         depends on DEBUG_KERNEL && PROC_FS
 213         help
 214           If you say Y here, additional code will be inserted into the
 215           timer routines to collect statistics about kernel timers being
 216           reprogrammed. The statistics can be read from /proc/timer_stats.
 217           The statistics collection is started by writing 1 to /proc/timer_stats,
 218           writing 0 stops it. This feature is useful to collect information
 219           about timer usage patterns in kernel and userspace. This feature
 220           is lightweight if enabled in the kernel config but not activated
 221           (it defaults to deactivated on bootup and will only be activated
 222           if some application like powertop activates it explicitly).
 223
 224 config DEBUG_OBJECTS
 225         bool "Debug object operations"
 226         depends on DEBUG_KERNEL
 227         help
 228           If you say Y here, additional code will be inserted into the
 229           kernel to track the life time of various objects and validate
 230           the operations on those objects.
 231
 232 config DEBUG_OBJECTS_SELFTEST
 233         bool "Debug objects selftest"
 234         depends on DEBUG_OBJECTS
 235         help
 236           This enables the selftest of the object debug code.
 237
 238 config DEBUG_OBJECTS_FREE
 239         bool "Debug objects in freed memory"
 240         depends on DEBUG_OBJECTS
 241         help
 242           This enables checks whether a k/v free operation frees an area
 243           which contains an object which has not been deactivated
 244           properly. This can make kmalloc/kfree-intensive workloads
 245           much slower.
 246
 247 config DEBUG_OBJECTS_TIMERS
 248         bool "Debug timer objects"
 249         depends on DEBUG_OBJECTS
 250         help
 251           If you say Y here, additional code will be inserted into the
 252           timer routines to track the life time of timer objects and
 253           validate the timer operations.
 254
 255 config DEBUG_OBJECTS_ENABLE_DEFAULT
 256         int "debug_objects bootup default value (0-1)"
 257         range 0 1
 258         default "1"
 259         depends on DEBUG_OBJECTS
 260         help
 261           Debug objects boot parameter default value
 262
 263 config DEBUG_SLAB
 264         bool "Debug slab memory allocations"
 265         depends on DEBUG_KERNEL && SLAB
 266         help
 267           Say Y here to have the kernel do limited verification on memory
 268           allocation as well as poisoning memory on free to catch use of freed
 269           memory. This can make kmalloc/kfree-intensive workloads much slower.
 270
 271 config DEBUG_SLAB_LEAK
 272         bool "Memory leak debugging"
 273         depends on DEBUG_SLAB
 274
 275 config SLUB_DEBUG_ON
 276         bool "SLUB debugging on by default"
 277         depends on SLUB && SLUB_DEBUG
 278         default n
 279         help
 280           Boot with debugging on by default. SLUB boots by default with
 281           the runtime debug capabilities switched off. Enabling this is
 282           equivalent to specifying the "slub_debug" parameter on boot.
 283           There is no support for more fine grained debug control like
 284           possible with slub_debug=xxx. SLUB debugging may be switched
 285           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 286           "slub_debug=-".
 287
 288 config SLUB_STATS
 289         default n
 290         bool "Enable SLUB performance statistics"
 291         depends on SLUB && SLUB_DEBUG && SYSFS
 292         help
 293           SLUB statistics are useful to debug SLUBs allocation behavior in
 294           order find ways to optimize the allocator. This should never be
 295           enabled for production use since keeping statistics slows down
 296           the allocator by a few percentage points. The slabinfo command
 297           supports the determination of the most active slabs to figure
 298           out which slabs are relevant to a particular load.
 299           Try running: slabinfo -DA
 300
 301 config DEBUG_PREEMPT
 302         bool "Debug preemptible kernel"
 303         depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
 304         default y
 305         help
 306           If you say Y here then the kernel will use a debug variant of the
 307           commonly used smp_processor_id() function and will print warnings
 308           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 309           will detect preemption count underflows.
 310
 311 config DEBUG_RT_MUTEXES
 312         bool "RT Mutex debugging, deadlock detection"
 313         depends on DEBUG_KERNEL && RT_MUTEXES
 314         help
 315          This allows rt mutex semantics violations and rt mutex related
 316          deadlocks (lockups) to be detected and reported automatically.
 317
 318 config DEBUG_PI_LIST
 319         bool
 320         default y
 321         depends on DEBUG_RT_MUTEXES
 322
 323 config RT_MUTEX_TESTER
 324         bool "Built-in scriptable tester for rt-mutexes"
 325         depends on DEBUG_KERNEL && RT_MUTEXES
 326         help
 327           This option enables a rt-mutex tester.
 328
 329 config DEBUG_SPINLOCK
 330         bool "Spinlock and rw-lock debugging: basic checks"
 331         depends on DEBUG_KERNEL
 332         help
 333           Say Y here and build SMP to catch missing spinlock initialization
 334           and certain other kinds of spinlock errors commonly made.  This is
 335           best used in conjunction with the NMI watchdog so that spinlock
 336           deadlocks are also debuggable.
 337
 338 config DEBUG_MUTEXES
 339         bool "Mutex debugging: basic checks"
 340         depends on DEBUG_KERNEL
 341         help
 342          This feature allows mutex semantics violations to be detected and
 343          reported.
 344
 345 config DEBUG_LOCK_ALLOC
 346         bool "Lock debugging: detect incorrect freeing of live locks"
 347         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 348         select DEBUG_SPINLOCK
 349         select DEBUG_MUTEXES
 350         select LOCKDEP
 351         help
 352          This feature will check whether any held lock (spinlock, rwlock,
 353          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 354          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 355          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 356          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 357          held during task exit.
 358
 359 config PROVE_LOCKING
 360         bool "Lock debugging: prove locking correctness"
 361         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 362         select LOCKDEP
 363         select DEBUG_SPINLOCK
 364         select DEBUG_MUTEXES
 365         select DEBUG_LOCK_ALLOC
 366         default n
 367         help
 368          This feature enables the kernel to prove that all locking
 369          that occurs in the kernel runtime is mathematically
 370          correct: that under no circumstance could an arbitrary (and
 371          not yet triggered) combination of observed locking
 372          sequences (on an arbitrary number of CPUs, running an
 373          arbitrary number of tasks and interrupt contexts) cause a
 374          deadlock.
 375
 376          In short, this feature enables the kernel to report locking
 377          related deadlocks before they actually occur.
 378
 379          The proof does not depend on how hard and complex a
 380          deadlock scenario would be to trigger: how many
 381          participant CPUs, tasks and irq-contexts would be needed
 382          for it to trigger. The proof also does not depend on
 383          timing: if a race and a resulting deadlock is possible
 384          theoretically (no matter how unlikely the race scenario
 385          is), it will be proven so and will immediately be
 386          reported by the kernel (once the event is observed that
 387          makes the deadlock theoretically possible).
 388
 389          If a deadlock is impossible (i.e. the locking rules, as
 390          observed by the kernel, are mathematically correct), the
 391          kernel reports nothing.
 392
 393          NOTE: this feature can also be enabled for rwlocks, mutexes
 394          and rwsems - in which case all dependencies between these
 395          different locking variants are observed and mapped too, and
 396          the proof of observed correctness is also maintained for an
 397          arbitrary combination of these separate locking variants.
 398
 399          For more details, see Documentation/lockdep-design.txt.
 400
 401 config LOCKDEP
 402         bool
 403         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 404         select STACKTRACE
 405         select FRAME_POINTER if !X86 && !MIPS && !PPC
 406         select KALLSYMS
 407         select KALLSYMS_ALL
 408
 409 config LOCK_STAT
 410         bool "Lock usage statistics"
 411         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 412         select LOCKDEP
 413         select DEBUG_SPINLOCK
 414         select DEBUG_MUTEXES
 415         select DEBUG_LOCK_ALLOC
 416         default n
 417         help
 418          This feature enables tracking lock contention points
 419
 420          For more details, see Documentation/lockstat.txt
 421
 422 config DEBUG_LOCKDEP
 423         bool "Lock dependency engine debugging"
 424         depends on DEBUG_KERNEL && LOCKDEP
 425         help
 426           If you say Y here, the lock dependency engine will do
 427           additional runtime checks to debug itself, at the price
 428           of more runtime overhead.
 429
 430 config TRACE_IRQFLAGS
 431         depends on DEBUG_KERNEL
 432         bool
 433         default y
 434         depends on TRACE_IRQFLAGS_SUPPORT
 435         depends on PROVE_LOCKING
 436
 437 config DEBUG_SPINLOCK_SLEEP
 438         bool "Spinlock debugging: sleep-inside-spinlock checking"
 439         depends on DEBUG_KERNEL
 440         help
 441           If you say Y here, various routines which may sleep will become very
 442           noisy if they are called with a spinlock held.
 443
 444 config DEBUG_LOCKING_API_SELFTESTS
 445         bool "Locking API boot-time self-tests"
 446         depends on DEBUG_KERNEL
 447         help
 448           Say Y here if you want the kernel to run a short self-test during
 449           bootup. The self-test checks whether common types of locking bugs
 450           are detected by debugging mechanisms or not. (if you disable
 451           lock debugging then those bugs wont be detected of course.)
 452           The following locking APIs are covered: spinlocks, rwlocks,
 453           mutexes and rwsems.
 454
 455 config STACKTRACE
 456         bool
 457         depends on STACKTRACE_SUPPORT
 458
 459 config DEBUG_KOBJECT
 460         bool "kobject debugging"
 461         depends on DEBUG_KERNEL
 462         help
 463           If you say Y here, some extra kobject debugging messages will be sent
 464           to the syslog.
 465
 466 config DEBUG_HIGHMEM
 467         bool "Highmem debugging"
 468         depends on DEBUG_KERNEL && HIGHMEM
 469         help
 470           This options enables addition error checking for high memory systems.
 471           Disable for production systems.
 472
 473 config DEBUG_BUGVERBOSE
 474         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 475         depends on BUG
 476         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
 477                    FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
 478         default !EMBEDDED
 479         help
 480           Say Y here to make BUG() panics output the file name and line number
 481           of the BUG call as well as the EIP and oops trace.  This aids
 482           debugging but costs about 70-100K of memory.
 483
 484 config DEBUG_INFO
 485         bool "Compile the kernel with debug info"
 486         depends on DEBUG_KERNEL
 487         help
 488           If you say Y here the resulting kernel image will include
 489           debugging info resulting in a larger kernel image.
 490           This adds debug symbols to the kernel and modules (gcc -g), and
 491           is needed if you intend to use kernel crashdump or binary object
 492           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 493           Say Y here only if you plan to debug the kernel.
 494
 495           If unsure, say N.
 496
 497 config DEBUG_VM
 498         bool "Debug VM"
 499         depends on DEBUG_KERNEL
 500         help
 501           Enable this to turn on extended checks in the virtual-memory system
 502           that may impact performance.
 503
 504           If unsure, say N.
 505
 506 config DEBUG_VIRTUAL
 507         bool "Debug VM translations"
 508         depends on DEBUG_KERNEL && X86
 509         help
 510           Enable some costly sanity checks in virtual to page code. This can
 511           catch mistakes with virt_to_page() and friends.
 512
 513           If unsure, say N.
 514
 515 config DEBUG_NOMMU_REGIONS
 516         bool "Debug the global anon/private NOMMU mapping region tree"
 517         depends on DEBUG_KERNEL && !MMU
 518         help
 519           This option causes the global tree of anonymous and private mapping
 520           regions to be regularly checked for invalid topology.
 521
 522 config DEBUG_WRITECOUNT
 523         bool "Debug filesystem writers count"
 524         depends on DEBUG_KERNEL
 525         help
 526           Enable this to catch wrong use of the writers count in struct
 527           vfsmount.  This will increase the size of each file struct by
 528           32 bits.
 529
 530           If unsure, say N.
 531
 532 config DEBUG_MEMORY_INIT
 533         bool "Debug memory initialisation" if EMBEDDED
 534         default !EMBEDDED
 535         help
 536           Enable this for additional checks during memory initialisation.
 537           The sanity checks verify aspects of the VM such as the memory model
 538           and other information provided by the architecture. Verbose
 539           information will be printed at KERN_DEBUG loglevel depending
 540           on the mminit_loglevel= command-line option.
 541
 542           If unsure, say Y
 543
 544 config DEBUG_LIST
 545         bool "Debug linked list manipulation"
 546         depends on DEBUG_KERNEL
 547         help
 548           Enable this to turn on extended checks in the linked-list
 549           walking routines.
 550
 551           If unsure, say N.
 552
 553 config DEBUG_SG
 554         bool "Debug SG table operations"
 555         depends on DEBUG_KERNEL
 556         help
 557           Enable this to turn on checks on scatter-gather tables. This can
 558           help find problems with drivers that do not properly initialize
 559           their sg tables.
 560
 561           If unsure, say N.
 562
 563 config DEBUG_NOTIFIERS
 564         bool "Debug notifier call chains"
 565         depends on DEBUG_KERNEL
 566         help
 567           Enable this to turn on sanity checking for notifier call chains.
 568           This is most useful for kernel developers to make sure that
 569           modules properly unregister themselves from notifier chains.
 570           This is a relatively cheap check but if you care about maximum
 571           performance, say N.
 572
 573 config FRAME_POINTER
 574         bool "Compile the kernel with frame pointers"
 575         depends on DEBUG_KERNEL && \
 576                 (CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \
 577                  AVR32 || SUPERH || BLACKFIN || MN10300) || \
 578                 ARCH_WANT_FRAME_POINTERS
 579         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 580         help
 581           If you say Y here the resulting kernel image will be slightly
 582           larger and slower, but it gives very useful debugging information
 583           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 584
 585 config BOOT_PRINTK_DELAY
 586         bool "Delay each boot printk message by N milliseconds"
 587         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 588         help
 589           This build option allows you to read kernel boot messages
 590           by inserting a short delay after each one.  The delay is
 591           specified in milliseconds on the kernel command line,
 592           using "boot_delay=N".
 593
 594           It is likely that you would also need to use "lpj=M" to preset
 595           the "loops per jiffie" value.
 596           See a previous boot log for the "lpj" value to use for your
 597           system, and then set "lpj=M" before setting "boot_delay=N".
 598           NOTE:  Using this option may adversely affect SMP systems.
 599           I.e., processors other than the first one may not boot up.
 600           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 601           what it believes to be lockup conditions.
 602
 603 config RCU_TORTURE_TEST
 604         tristate "torture tests for RCU"
 605         depends on DEBUG_KERNEL
 606         default n
 607         help
 608           This option provides a kernel module that runs torture tests
 609           on the RCU infrastructure.  The kernel module may be built
 610           after the fact on the running kernel to be tested, if desired.
 611
 612           Say Y here if you want RCU torture tests to be built into
 613           the kernel.
 614           Say M if you want the RCU torture tests to build as a module.
 615           Say N if you are unsure.
 616
 617 config RCU_TORTURE_TEST_RUNNABLE
 618         bool "torture tests for RCU runnable by default"
 619         depends on RCU_TORTURE_TEST = y
 620         default n
 621         help
 622           This option provides a way to build the RCU torture tests
 623           directly into the kernel without them starting up at boot
 624           time.  You can use /proc/sys/kernel/rcutorture_runnable
 625           to manually override this setting.  This /proc file is
 626           available only when the RCU torture tests have been built
 627           into the kernel.
 628
 629           Say Y here if you want the RCU torture tests to start during
 630           boot (you probably don't).
 631           Say N here if you want the RCU torture tests to start only
 632           after being manually enabled via /proc.
 633
 634 config RCU_CPU_STALL_DETECTOR
 635         bool "Check for stalled CPUs delaying RCU grace periods"
 636         depends on CLASSIC_RCU
 637         default n
 638         help
 639           This option causes RCU to printk information on which
 640           CPUs are delaying the current grace period, but only when
 641           the grace period extends for excessive time periods.
 642
 643           Say Y if you want RCU to perform such checks.
 644
 645           Say N if you are unsure.
 646
 647 config RCU_CPU_STALL_DETECTOR
 648         bool "Check for stalled CPUs delaying RCU grace periods"
 649         depends on CLASSIC_RCU || TREE_RCU
 650         default n
 651         help
 652           This option causes RCU to printk information on which
 653           CPUs are delaying the current grace period, but only when
 654           the grace period extends for excessive time periods.
 655
 656           Say Y if you want RCU to perform such checks.
 657
 658           Say N if you are unsure.
 659
 660 config KPROBES_SANITY_TEST
 661         bool "Kprobes sanity tests"
 662         depends on DEBUG_KERNEL
 663         depends on KPROBES
 664         default n
 665         help
 666           This option provides for testing basic kprobes functionality on
 667           boot. A sample kprobe, jprobe and kretprobe are inserted and
 668           verified for functionality.
 669
 670           Say N if you are unsure.
 671
 672 config BACKTRACE_SELF_TEST
 673         tristate "Self test for the backtrace code"
 674         depends on DEBUG_KERNEL
 675         default n
 676         help
 677           This option provides a kernel module that can be used to test
 678           the kernel stack backtrace code. This option is not useful
 679           for distributions or general kernels, but only for kernel
 680           developers working on architecture code.
 681
 682           Note that if you want to also test saved backtraces, you will
 683           have to enable STACKTRACE as well.
 684
 685           Say N if you are unsure.
 686
 687 config DEBUG_BLOCK_EXT_DEVT
 688         bool "Force extended block device numbers and spread them"
 689         depends on DEBUG_KERNEL
 690         depends on BLOCK
 691         default n
 692         help
 693           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
 694           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
 695           YOU ARE DOING.  Distros, please enable this and fix whatever
 696           is broken.
 697
 698           Conventionally, block device numbers are allocated from
 699           predetermined contiguous area.  However, extended block area
 700           may introduce non-contiguous block device numbers.  This
 701           option forces most block device numbers to be allocated from
 702           the extended space and spreads them to discover kernel or
 703           userland code paths which assume predetermined contiguous
 704           device number allocation.
 705
 706           Note that turning on this debug option shuffles all the
 707           device numbers for all IDE and SCSI devices including libata
 708           ones, so root partition specified using device number
 709           directly (via rdev or root=MAJ:MIN) won't work anymore.
 710           Textual device names (root=/dev/sdXn) will continue to work.
 711
 712           Say N if you are unsure.
 713
 714 config LKDTM
 715         tristate "Linux Kernel Dump Test Tool Module"
 716         depends on DEBUG_KERNEL
 717         depends on KPROBES
 718         depends on BLOCK
 719         default n
 720         help
 721         This module enables testing of the different dumping mechanisms by
 722         inducing system failures at predefined crash points.
 723         If you don't need it: say N
 724         Choose M here to compile this code as a module. The module will be
 725         called lkdtm.
 726
 727         Documentation on how to use the module can be found in
 728         drivers/misc/lkdtm.c
 729
 730 config FAULT_INJECTION
 731         bool "Fault-injection framework"
 732         depends on DEBUG_KERNEL
 733         help
 734           Provide fault-injection framework.
 735           For more details, see Documentation/fault-injection/.
 736
 737 config FAILSLAB
 738         bool "Fault-injection capability for kmalloc"
 739         depends on FAULT_INJECTION
 740         depends on SLAB || SLUB
 741         help
 742           Provide fault-injection capability for kmalloc.
 743
 744 config FAIL_PAGE_ALLOC
 745         bool "Fault-injection capabilitiy for alloc_pages()"
 746         depends on FAULT_INJECTION
 747         help
 748           Provide fault-injection capability for alloc_pages().
 749
 750 config FAIL_MAKE_REQUEST
 751         bool "Fault-injection capability for disk IO"
 752         depends on FAULT_INJECTION && BLOCK
 753         help
 754           Provide fault-injection capability for disk IO.
 755
 756 config FAIL_IO_TIMEOUT
 757         bool "Faul-injection capability for faking disk interrupts"
 758         depends on FAULT_INJECTION && BLOCK
 759         help
 760           Provide fault-injection capability on end IO handling. This
 761           will make the block layer "forget" an interrupt as configured,
 762           thus exercising the error handling.
 763
 764           Only works with drivers that use the generic timeout handling,
 765           for others it wont do anything.
 766
 767 config FAULT_INJECTION_DEBUG_FS
 768         bool "Debugfs entries for fault-injection capabilities"
 769         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 770         help
 771           Enable configuration of fault-injection capabilities via debugfs.
 772
 773 config FAULT_INJECTION_STACKTRACE_FILTER
 774         bool "stacktrace filter for fault-injection capabilities"
 775         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 776         depends on !X86_64
 777         select STACKTRACE
 778         select FRAME_POINTER if !PPC
 779         help
 780           Provide stacktrace filter for fault-injection capabilities
 781
 782 config LATENCYTOP
 783         bool "Latency measuring infrastructure"
 784         select FRAME_POINTER if !MIPS && !PPC
 785         select KALLSYMS
 786         select KALLSYMS_ALL
 787         select STACKTRACE
 788         select SCHEDSTATS
 789         select SCHED_DEBUG
 790         depends on HAVE_LATENCYTOP_SUPPORT
 791         help
 792           Enable this option if you want to use the LatencyTOP tool
 793           to find out which userspace is blocking on what kernel operations.
 794
 795 config SYSCTL_SYSCALL_CHECK
 796         bool "Sysctl checks"
 797         depends on SYSCTL_SYSCALL
 798         ---help---
 799           sys_sysctl uses binary paths that have been found challenging
 800           to properly maintain and use. This enables checks that help
 801           you to keep things correct.
 802
 803 source kernel/trace/Kconfig
 804
 805 config PROVIDE_OHCI1394_DMA_INIT
 806         bool "Remote debugging over FireWire early on boot"
 807         depends on PCI && X86
 808         help
 809           If you want to debug problems which hang or crash the kernel early
 810           on boot and the crashing machine has a FireWire port, you can use
 811           this feature to remotely access the memory of the crashed machine
 812           over FireWire. This employs remote DMA as part of the OHCI1394
 813           specification which is now the standard for FireWire controllers.
 814
 815           With remote DMA, you can monitor the printk buffer remotely using
 816           firescope and access all memory below 4GB using fireproxy from gdb.
 817           Even controlling a kernel debugger is possible using remote DMA.
 818
 819           Usage:
 820
 821           If ohci1394_dma=early is used as boot parameter, it will initialize
 822           all OHCI1394 controllers which are found in the PCI config space.
 823
 824           As all changes to the FireWire bus such as enabling and disabling
 825           devices cause a bus reset and thereby disable remote DMA for all
 826           devices, be sure to have the cable plugged and FireWire enabled on
 827           the debugging host before booting the debug target for debugging.
 828
 829           This code (~1k) is freed after boot. By then, the firewire stack
 830           in charge of the OHCI-1394 controllers should be used instead.
 831
 832           See Documentation/debugging-via-ohci1394.txt for more information.
 833
 834 config FIREWIRE_OHCI_REMOTE_DMA
 835         bool "Remote debugging over FireWire with firewire-ohci"
 836         depends on FIREWIRE_OHCI
 837         help
 838           This option lets you use the FireWire bus for remote debugging
 839           with help of the firewire-ohci driver. It enables unfiltered
 840           remote DMA in firewire-ohci.
 841           See Documentation/debugging-via-ohci1394.txt for more information.
 842
 843           If unsure, say N.
 844
 845 menuconfig BUILD_DOCSRC
 846         bool "Build targets in Documentation/ tree"
 847         depends on HEADERS_CHECK
 848         help
 849           This option attempts to build objects from the source files in the
 850           kernel Documentation/ tree.
 851
 852           Say N if you are unsure.
 853
 854 config DYNAMIC_PRINTK_DEBUG
 855         bool "Enable dynamic printk() call support"
 856         default n
 857         depends on PRINTK
 858         select PRINTK_DEBUG
 859         help
 860
 861           Compiles debug level messages into the kernel, which would not
 862           otherwise be available at runtime. These messages can then be
 863           enabled/disabled on a per module basis. This mechanism implicitly
 864           enables all pr_debug() and dev_dbg() calls. The impact of this
 865           compile option is a larger kernel text size of about 2%.
 866
 867           Usage:
 868
 869           Dynamic debugging is controlled by the debugfs file,
 870           dynamic_printk/modules. This file contains a list of the modules that
 871           can be enabled. The format of the file is the module name, followed
 872           by a set of flags that can be enabled. The first flag is always the
 873           'enabled' flag. For example:
 874
 875                 <module_name> <enabled=0/1>
 876                                 .
 877                                 .
 878                                 .
 879
 880           <module_name> : Name of the module in which the debug call resides
 881           <enabled=0/1> : whether the messages are enabled or not
 882
 883           From a live system:
 884
 885                 snd_hda_intel enabled=0
 886                 fixup enabled=0
 887                 driver enabled=0
 888
 889           Enable a module:
 890
 891                 $echo "set enabled=1 <module_name>" > dynamic_printk/modules
 892
 893           Disable a module:
 894
 895                 $echo "set enabled=0 <module_name>" > dynamic_printk/modules
 896
 897           Enable all modules:
 898
 899                 $echo "set enabled=1 all" > dynamic_printk/modules
 900
 901           Disable all modules:
 902
 903                 $echo "set enabled=0 all" > dynamic_printk/modules
 904
 905           Finally, passing "dynamic_printk" at the command line enables
 906           debugging for all modules. This mode can be turned off via the above
 907           disable command.
 908
 909 source "samples/Kconfig"
 910
 911 source "lib/Kconfig.kgdb"