lib/Kconfig.debug

   1 menu "printk and dmesg options"
   2
   3 config PRINTK_TIME
   4         bool "Show timing information on printks"
   5         depends on PRINTK
   6         help
   7           Selecting this option causes time stamps of the printk()
   8           messages to be added to the output of the syslog() system
   9           call and at the console.
  10
  11           The timestamp is always recorded internally, and exported
  12           to /dev/kmsg. This flag just specifies if the timestamp should
  13           be included, not that the timestamp is recorded.
  14
  15           The behavior is also controlled by the kernel command line
  16           parameter printk.time=1. See Documentation/kernel-parameters.txt
  17
  18 config DEFAULT_MESSAGE_LOGLEVEL
  19         int "Default message log level (1-7)"
  20         range 1 7
  21         default "4"
  22         help
  23           Default log level for printk statements with no specified priority.
  24
  25           This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
  26           that are auditing their logs closely may want to set it to a lower
  27           priority.
  28
  29 config BOOT_PRINTK_DELAY
  30         bool "Delay each boot printk message by N milliseconds"
  31         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
  32         help
  33           This build option allows you to read kernel boot messages
  34           by inserting a short delay after each one.  The delay is
  35           specified in milliseconds on the kernel command line,
  36           using "boot_delay=N".
  37
  38           It is likely that you would also need to use "lpj=M" to preset
  39           the "loops per jiffie" value.
  40           See a previous boot log for the "lpj" value to use for your
  41           system, and then set "lpj=M" before setting "boot_delay=N".
  42           NOTE:  Using this option may adversely affect SMP systems.
  43           I.e., processors other than the first one may not boot up.
  44           BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
  45           what it believes to be lockup conditions.
  46
  47 config DYNAMIC_DEBUG
  48         bool "Enable dynamic printk() support"
  49         default n
  50         depends on PRINTK
  51         depends on DEBUG_FS
  52         help
  53
  54           Compiles debug level messages into the kernel, which would not
  55           otherwise be available at runtime. These messages can then be
  56           enabled/disabled based on various levels of scope - per source file,
  57           function, module, format string, and line number. This mechanism
  58           implicitly compiles in all pr_debug() and dev_dbg() calls, which
  59           enlarges the kernel text size by about 2%.
  60
  61           If a source file is compiled with DEBUG flag set, any
  62           pr_debug() calls in it are enabled by default, but can be
  63           disabled at runtime as below.  Note that DEBUG flag is
  64           turned on by many CONFIG_*DEBUG* options.
  65
  66           Usage:
  67
  68           Dynamic debugging is controlled via the 'dynamic_debug/control' file,
  69           which is contained in the 'debugfs' filesystem. Thus, the debugfs
  70           filesystem must first be mounted before making use of this feature.
  71           We refer the control file as: <debugfs>/dynamic_debug/control. This
  72           file contains a list of the debug statements that can be enabled. The
  73           format for each line of the file is:
  74
  75                 filename:lineno [module]function flags format
  76
  77           filename : source file of the debug statement
  78           lineno : line number of the debug statement
  79           module : module that contains the debug statement
  80           function : function that contains the debug statement
  81           flags : '=p' means the line is turned 'on' for printing
  82           format : the format used for the debug statement
  83
  84           From a live system:
  85
  86                 nullarbor:~ # cat <debugfs>/dynamic_debug/control
  87                 # filename:lineno [module]function flags format
  88                 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
  89                 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
  90                 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
  91
  92           Example usage:
  93
  94                 // enable the message at line 1603 of file svcsock.c
  95                 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
  96                                                 <debugfs>/dynamic_debug/control
  97
  98                 // enable all the messages in file svcsock.c
  99                 nullarbor:~ # echo -n 'file svcsock.c +p' >
 100                                                 <debugfs>/dynamic_debug/control
 101
 102                 // enable all the messages in the NFS server module
 103                 nullarbor:~ # echo -n 'module nfsd +p' >
 104                                                 <debugfs>/dynamic_debug/control
 105
 106                 // enable all 12 messages in the function svc_process()
 107                 nullarbor:~ # echo -n 'func svc_process +p' >
 108                                                 <debugfs>/dynamic_debug/control
 109
 110                 // disable all 12 messages in the function svc_process()
 111                 nullarbor:~ # echo -n 'func svc_process -p' >
 112                                                 <debugfs>/dynamic_debug/control
 113
 114           See Documentation/dynamic-debug-howto.txt for additional information.
 115
 116 endmenu # "printk and dmesg options"
 117
 118 menu "Compile-time checks and compiler options"
 119
 120 config DEBUG_INFO
 121         bool "Compile the kernel with debug info"
 122         depends on DEBUG_KERNEL
 123         help
 124           If you say Y here the resulting kernel image will include
 125           debugging info resulting in a larger kernel image.
 126           This adds debug symbols to the kernel and modules (gcc -g), and
 127           is needed if you intend to use kernel crashdump or binary object
 128           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 129           Say Y here only if you plan to debug the kernel.
 130
 131           If unsure, say N.
 132
 133 config DEBUG_INFO_REDUCED
 134         bool "Reduce debugging information"
 135         depends on DEBUG_INFO
 136         help
 137           If you say Y here gcc is instructed to generate less debugging
 138           information for structure types. This means that tools that
 139           need full debugging information (like kgdb or systemtap) won't
 140           be happy. But if you merely need debugging information to
 141           resolve line numbers there is no loss. Advantage is that
 142           build directory object sizes shrink dramatically over a full
 143           DEBUG_INFO build and compile times are reduced too.
 144           Only works with newer gcc versions.
 145
 146 config ENABLE_WARN_DEPRECATED
 147         bool "Enable __deprecated logic"
 148         default y
 149         help
 150           Enable the __deprecated logic in the kernel build.
 151           Disable this to suppress the "warning: 'foo' is deprecated
 152           (declared at kernel/power/somefile.c:1234)" messages.
 153
 154 config ENABLE_MUST_CHECK
 155         bool "Enable __must_check logic"
 156         default y
 157         help
 158           Enable the __must_check logic in the kernel build.  Disable this to
 159           suppress the "warning: ignoring return value of 'foo', declared with
 160           attribute warn_unused_result" messages.
 161
 162 config FRAME_WARN
 163         int "Warn for stack frames larger than (needs gcc 4.4)"
 164         range 0 8192
 165         default 1024 if !64BIT
 166         default 2048 if 64BIT
 167         help
 168           Tell gcc to warn at build time for stack frames larger than this.
 169           Setting this too low will cause a lot of warnings.
 170           Setting it to 0 disables the warning.
 171           Requires gcc 4.4
 172
 173 config STRIP_ASM_SYMS
 174         bool "Strip assembler-generated symbols during link"
 175         default n
 176         help
 177           Strip internal assembler-generated symbols during a link (symbols
 178           that look like '.Lxxx') so they don't pollute the output of
 179           get_wchan() and suchlike.
 180
 181 config READABLE_ASM
 182         bool "Generate readable assembler code"
 183         depends on DEBUG_KERNEL
 184         help
 185           Disable some compiler optimizations that tend to generate human unreadable
 186           assembler output. This may make the kernel slightly slower, but it helps
 187           to keep kernel developers who have to stare a lot at assembler listings
 188           sane.
 189
 190 config UNUSED_SYMBOLS
 191         bool "Enable unused/obsolete exported symbols"
 192         default y if X86
 193         help
 194           Unused but exported symbols make the kernel needlessly bigger.  For
 195           that reason most of these unused exports will soon be removed.  This
 196           option is provided temporarily to provide a transition period in case
 197           some external kernel module needs one of these symbols anyway. If you
 198           encounter such a case in your module, consider if you are actually
 199           using the right API.  (rationale: since nobody in the kernel is using
 200           this in a module, there is a pretty good chance it's actually the
 201           wrong interface to use).  If you really need the symbol, please send a
 202           mail to the linux kernel mailing list mentioning the symbol and why
 203           you really need it, and what the merge plan to the mainline kernel for
 204           your module is.
 205
 206 config DEBUG_FS
 207         bool "Debug Filesystem"
 208         help
 209           debugfs is a virtual file system that kernel developers use to put
 210           debugging files into.  Enable this option to be able to read and
 211           write to these files.
 212
 213           For detailed documentation on the debugfs API, see
 214           Documentation/DocBook/filesystems.
 215
 216           If unsure, say N.
 217
 218 config HEADERS_CHECK
 219         bool "Run 'make headers_check' when building vmlinux"
 220         depends on !UML
 221         help
 222           This option will extract the user-visible kernel headers whenever
 223           building the kernel, and will run basic sanity checks on them to
 224           ensure that exported files do not attempt to include files which
 225           were not exported, etc.
 226
 227           If you're making modifications to header files which are
 228           relevant for userspace, say 'Y', and check the headers
 229           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
 230           your build tree), to make sure they're suitable.
 231
 232 config DEBUG_SECTION_MISMATCH
 233         bool "Enable full Section mismatch analysis"
 234         help
 235           The section mismatch analysis checks if there are illegal
 236           references from one section to another section.
 237           During linktime or runtime, some sections are dropped;
 238           any use of code/data previously in these sections would
 239           most likely result in an oops.
 240           In the code, functions and variables are annotated with
 241           __init, __cpuinit, etc. (see the full list in include/linux/init.h),
 242           which results in the code/data being placed in specific sections.
 243           The section mismatch analysis is always performed after a full
 244           kernel build, and enabling this option causes the following
 245           additional steps to occur:
 246           - Add the option -fno-inline-functions-called-once to gcc commands.
 247             When inlining a function annotated with __init in a non-init
 248             function, we would lose the section information and thus
 249             the analysis would not catch the illegal reference.
 250             This option tells gcc to inline less (but it does result in
 251             a larger kernel).
 252           - Run the section mismatch analysis for each module/built-in.o file.
 253             When we run the section mismatch analysis on vmlinux.o, we
 254             lose valueble information about where the mismatch was
 255             introduced.
 256             Running the analysis for each module/built-in.o file
 257             tells where the mismatch happens much closer to the
 258             source. The drawback is that the same mismatch is
 259             reported at least twice.
 260           - Enable verbose reporting from modpost in order to help resolve
 261             the section mismatches that are reported.
 262
 263 #
 264 # Select this config option from the architecture Kconfig, if it
 265 # is preferred to always offer frame pointers as a config
 266 # option on the architecture (regardless of KERNEL_DEBUG):
 267 #
 268 config ARCH_WANT_FRAME_POINTERS
 269         bool
 270         help
 271
 272 config FRAME_POINTER
 273         bool "Compile the kernel with frame pointers"
 274         depends on DEBUG_KERNEL && \
 275                 (CRIS || M68K || FRV || UML || \
 276                  AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
 277                 ARCH_WANT_FRAME_POINTERS
 278         default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
 279         help
 280           If you say Y here the resulting kernel image will be slightly
 281           larger and slower, but it gives very useful debugging information
 282           in case of kernel bugs. (precise oopses/stacktraces/warnings)
 283
 284 config DEBUG_FORCE_WEAK_PER_CPU
 285         bool "Force weak per-cpu definitions"
 286         depends on DEBUG_KERNEL
 287         help
 288           s390 and alpha require percpu variables in modules to be
 289           defined weak to work around addressing range issue which
 290           puts the following two restrictions on percpu variable
 291           definitions.
 292
 293           1. percpu symbols must be unique whether static or not
 294           2. percpu variables can't be defined inside a function
 295
 296           To ensure that generic code follows the above rules, this
 297           option forces all percpu variables to be defined as weak.
 298
 299 endmenu # "Compiler options"
 300
 301 config MAGIC_SYSRQ
 302         bool "Magic SysRq key"
 303         depends on !UML
 304         help
 305           If you say Y here, you will have some control over the system even
 306           if the system crashes for example during kernel debugging (e.g., you
 307           will be able to flush the buffer cache to disk, reboot the system
 308           immediately or dump some status information). This is accomplished
 309           by pressing various keys while holding SysRq (Alt+PrintScreen). It
 310           also works on a serial console (on PC hardware at least), if you
 311           send a BREAK and then within 5 seconds a command keypress. The
 312           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
 313           unless you really know what this hack does.
 314
 315 config DEBUG_KERNEL
 316         bool "Kernel debugging"
 317         help
 318           Say Y here if you are developing drivers or trying to debug and
 319           identify kernel problems.
 320
 321 menu "Memory Debugging"
 322
 323 source mm/Kconfig.debug
 324
 325 config DEBUG_OBJECTS
 326         bool "Debug object operations"
 327         depends on DEBUG_KERNEL
 328         help
 329           If you say Y here, additional code will be inserted into the
 330           kernel to track the life time of various objects and validate
 331           the operations on those objects.
 332
 333 config DEBUG_OBJECTS_SELFTEST
 334         bool "Debug objects selftest"
 335         depends on DEBUG_OBJECTS
 336         help
 337           This enables the selftest of the object debug code.
 338
 339 config DEBUG_OBJECTS_FREE
 340         bool "Debug objects in freed memory"
 341         depends on DEBUG_OBJECTS
 342         help
 343           This enables checks whether a k/v free operation frees an area
 344           which contains an object which has not been deactivated
 345           properly. This can make kmalloc/kfree-intensive workloads
 346           much slower.
 347
 348 config DEBUG_OBJECTS_TIMERS
 349         bool "Debug timer objects"
 350         depends on DEBUG_OBJECTS
 351         help
 352           If you say Y here, additional code will be inserted into the
 353           timer routines to track the life time of timer objects and
 354           validate the timer operations.
 355
 356 config DEBUG_OBJECTS_WORK
 357         bool "Debug work objects"
 358         depends on DEBUG_OBJECTS
 359         help
 360           If you say Y here, additional code will be inserted into the
 361           work queue routines to track the life time of work objects and
 362           validate the work operations.
 363
 364 config DEBUG_OBJECTS_RCU_HEAD
 365         bool "Debug RCU callbacks objects"
 366         depends on DEBUG_OBJECTS
 367         help
 368           Enable this to turn on debugging of RCU list heads (call_rcu() usage).
 369
 370 config DEBUG_OBJECTS_PERCPU_COUNTER
 371         bool "Debug percpu counter objects"
 372         depends on DEBUG_OBJECTS
 373         help
 374           If you say Y here, additional code will be inserted into the
 375           percpu counter routines to track the life time of percpu counter
 376           objects and validate the percpu counter operations.
 377
 378 config DEBUG_OBJECTS_ENABLE_DEFAULT
 379         int "debug_objects bootup default value (0-1)"
 380         range 0 1
 381         default "1"
 382         depends on DEBUG_OBJECTS
 383         help
 384           Debug objects boot parameter default value
 385
 386 config DEBUG_SLAB
 387         bool "Debug slab memory allocations"
 388         depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
 389         help
 390           Say Y here to have the kernel do limited verification on memory
 391           allocation as well as poisoning memory on free to catch use of freed
 392           memory. This can make kmalloc/kfree-intensive workloads much slower.
 393
 394 config DEBUG_SLAB_LEAK
 395         bool "Memory leak debugging"
 396         depends on DEBUG_SLAB
 397
 398 config SLUB_DEBUG_ON
 399         bool "SLUB debugging on by default"
 400         depends on SLUB && SLUB_DEBUG && !KMEMCHECK
 401         default n
 402         help
 403           Boot with debugging on by default. SLUB boots by default with
 404           the runtime debug capabilities switched off. Enabling this is
 405           equivalent to specifying the "slub_debug" parameter on boot.
 406           There is no support for more fine grained debug control like
 407           possible with slub_debug=xxx. SLUB debugging may be switched
 408           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 409           "slub_debug=-".
 410
 411 config SLUB_STATS
 412         default n
 413         bool "Enable SLUB performance statistics"
 414         depends on SLUB && SYSFS
 415         help
 416           SLUB statistics are useful to debug SLUBs allocation behavior in
 417           order find ways to optimize the allocator. This should never be
 418           enabled for production use since keeping statistics slows down
 419           the allocator by a few percentage points. The slabinfo command
 420           supports the determination of the most active slabs to figure
 421           out which slabs are relevant to a particular load.
 422           Try running: slabinfo -DA
 423
 424 config HAVE_DEBUG_KMEMLEAK
 425         bool
 426
 427 config DEBUG_KMEMLEAK
 428         bool "Kernel memory leak detector"
 429         depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
 430         select DEBUG_FS
 431         select STACKTRACE if STACKTRACE_SUPPORT
 432         select KALLSYMS
 433         select CRC32
 434         help
 435           Say Y here if you want to enable the memory leak
 436           detector. The memory allocation/freeing is traced in a way
 437           similar to the Boehm's conservative garbage collector, the
 438           difference being that the orphan objects are not freed but
 439           only shown in /sys/kernel/debug/kmemleak. Enabling this
 440           feature will introduce an overhead to memory
 441           allocations. See Documentation/kmemleak.txt for more
 442           details.
 443
 444           Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
 445           of finding leaks due to the slab objects poisoning.
 446
 447           In order to access the kmemleak file, debugfs needs to be
 448           mounted (usually at /sys/kernel/debug).
 449
 450 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
 451         int "Maximum kmemleak early log entries"
 452         depends on DEBUG_KMEMLEAK
 453         range 200 40000
 454         default 400
 455         help
 456           Kmemleak must track all the memory allocations to avoid
 457           reporting false positives. Since memory may be allocated or
 458           freed before kmemleak is initialised, an early log buffer is
 459           used to store these actions. If kmemleak reports "early log
 460           buffer exceeded", please increase this value.
 461
 462 config DEBUG_KMEMLEAK_TEST
 463         tristate "Simple test for the kernel memory leak detector"
 464         depends on DEBUG_KMEMLEAK && m
 465         help
 466           This option enables a module that explicitly leaks memory.
 467
 468           If unsure, say N.
 469
 470 config DEBUG_KMEMLEAK_DEFAULT_OFF
 471         bool "Default kmemleak to off"
 472         depends on DEBUG_KMEMLEAK
 473         help
 474           Say Y here to disable kmemleak by default. It can then be enabled
 475           on the command line via kmemleak=on.
 476
 477 config DEBUG_STACK_USAGE
 478         bool "Stack utilization instrumentation"
 479         depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
 480         help
 481           Enables the display of the minimum amount of free stack which each
 482           task has ever had available in the sysrq-T and sysrq-P debug output.
 483
 484           This option will slow down process creation somewhat.
 485
 486 config DEBUG_VM
 487         bool "Debug VM"
 488         depends on DEBUG_KERNEL
 489         help
 490           Enable this to turn on extended checks in the virtual-memory system
 491           that may impact performance.
 492
 493           If unsure, say N.
 494
 495 config DEBUG_VM_RB
 496         bool "Debug VM red-black trees"
 497         depends on DEBUG_VM
 498         help
 499           Enable this to turn on more extended checks in the virtual-memory
 500           system that may impact performance.
 501
 502           If unsure, say N.
 503
 504 config DEBUG_VIRTUAL
 505         bool "Debug VM translations"
 506         depends on DEBUG_KERNEL && X86
 507         help
 508           Enable some costly sanity checks in virtual to page code. This can
 509           catch mistakes with virt_to_page() and friends.
 510
 511           If unsure, say N.
 512
 513 config DEBUG_NOMMU_REGIONS
 514         bool "Debug the global anon/private NOMMU mapping region tree"
 515         depends on DEBUG_KERNEL && !MMU
 516         help
 517           This option causes the global tree of anonymous and private mapping
 518           regions to be regularly checked for invalid topology.
 519
 520 config DEBUG_MEMORY_INIT
 521         bool "Debug memory initialisation" if EXPERT
 522         default !EXPERT
 523         help
 524           Enable this for additional checks during memory initialisation.
 525           The sanity checks verify aspects of the VM such as the memory model
 526           and other information provided by the architecture. Verbose
 527           information will be printed at KERN_DEBUG loglevel depending
 528           on the mminit_loglevel= command-line option.
 529
 530           If unsure, say Y
 531
 532 config MEMORY_NOTIFIER_ERROR_INJECT
 533         tristate "Memory hotplug notifier error injection module"
 534         depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
 535         help
 536           This option provides the ability to inject artificial errors to
 537           memory hotplug notifier chain callbacks.  It is controlled through
 538           debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
 539
 540           If the notifier call chain should be failed with some events
 541           notified, write the error code to "actions/<notifier event>/error".
 542
 543           Example: Inject memory hotplug offline error (-12 == -ENOMEM)
 544
 545           # cd /sys/kernel/debug/notifier-error-inject/memory
 546           # echo -12 > actions/MEM_GOING_OFFLINE/error
 547           # echo offline > /sys/devices/system/memory/memoryXXX/state
 548           bash: echo: write error: Cannot allocate memory
 549
 550           To compile this code as a module, choose M here: the module will
 551           be called memory-notifier-error-inject.
 552
 553           If unsure, say N.
 554
 555 config DEBUG_PER_CPU_MAPS
 556         bool "Debug access to per_cpu maps"
 557         depends on DEBUG_KERNEL
 558         depends on SMP
 559         help
 560           Say Y to verify that the per_cpu map being accessed has
 561           been set up. This adds a fair amount of code to kernel memory
 562           and decreases performance.
 563
 564           Say N if unsure.
 565
 566 config DEBUG_HIGHMEM
 567         bool "Highmem debugging"
 568         depends on DEBUG_KERNEL && HIGHMEM
 569         help
 570           This options enables addition error checking for high memory systems.
 571           Disable for production systems.
 572
 573 config HAVE_DEBUG_STACKOVERFLOW
 574         bool
 575
 576 config DEBUG_STACKOVERFLOW
 577         bool "Check for stack overflows"
 578         depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
 579         ---help---
 580           Say Y here if you want to check for overflows of kernel, IRQ
 581           and exception stacks (if your archicture uses them). This
 582           option will show detailed messages if free stack space drops
 583           below a certain limit.
 584
 585           These kinds of bugs usually occur when call-chains in the
 586           kernel get too deep, especially when interrupts are
 587           involved.
 588
 589           Use this in cases where you see apparently random memory
 590           corruption, especially if it appears in 'struct thread_info'
 591
 592           If in doubt, say "N".
 593
 594 source "lib/Kconfig.kmemcheck"
 595
 596 endmenu # "Memory Debugging"
 597
 598 config DEBUG_SHIRQ
 599         bool "Debug shared IRQ handlers"
 600         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
 601         help
 602           Enable this to generate a spurious interrupt as soon as a shared
 603           interrupt handler is registered, and just before one is deregistered.
 604           Drivers ought to be able to handle interrupts coming in at those
 605           points; some don't and need to be caught.
 606
 607 config LOCKUP_DETECTOR
 608         bool "Detect Hard and Soft Lockups"
 609         depends on DEBUG_KERNEL && !S390
 610         help
 611           Say Y here to enable the kernel to act as a watchdog to detect
 612           hard and soft lockups.
 613
 614           Softlockups are bugs that cause the kernel to loop in kernel
 615           mode for more than 20 seconds, without giving other tasks a
 616           chance to run.  The current stack trace is displayed upon
 617           detection and the system will stay locked up.
 618
 619           Hardlockups are bugs that cause the CPU to loop in kernel mode
 620           for more than 10 seconds, without letting other interrupts have a
 621           chance to run.  The current stack trace is displayed upon detection
 622           and the system will stay locked up.
 623
 624           The overhead should be minimal.  A periodic hrtimer runs to
 625           generate interrupts and kick the watchdog task every 4 seconds.
 626           An NMI is generated every 10 seconds or so to check for hardlockups.
 627
 628           The frequency of hrtimer and NMI events and the soft and hard lockup
 629           thresholds can be controlled through the sysctl watchdog_thresh.
 630
 631 config HARDLOCKUP_DETECTOR
 632         def_bool y
 633         depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
 634         depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
 635
 636 config BOOTPARAM_HARDLOCKUP_PANIC
 637         bool "Panic (Reboot) On Hard Lockups"
 638         depends on HARDLOCKUP_DETECTOR
 639         help
 640           Say Y here to enable the kernel to panic on "hard lockups",
 641           which are bugs that cause the kernel to loop in kernel
 642           mode with interrupts disabled for more than 10 seconds (configurable
 643           using the watchdog_thresh sysctl).
 644
 645           Say N if unsure.
 646
 647 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
 648         int
 649         depends on HARDLOCKUP_DETECTOR
 650         range 0 1
 651         default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
 652         default 1 if BOOTPARAM_HARDLOCKUP_PANIC
 653
 654 config BOOTPARAM_SOFTLOCKUP_PANIC
 655         bool "Panic (Reboot) On Soft Lockups"
 656         depends on LOCKUP_DETECTOR
 657         help
 658           Say Y here to enable the kernel to panic on "soft lockups",
 659           which are bugs that cause the kernel to loop in kernel
 660           mode for more than 20 seconds (configurable using the watchdog_thresh
 661           sysctl), without giving other tasks a chance to run.
 662
 663           The panic can be used in combination with panic_timeout,
 664           to cause the system to reboot automatically after a
 665           lockup has been detected. This feature is useful for
 666           high-availability systems that have uptime guarantees and
 667           where a lockup must be resolved ASAP.
 668
 669           Say N if unsure.
 670
 671 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
 672         int
 673         depends on LOCKUP_DETECTOR
 674         range 0 1
 675         default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
 676         default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
 677
 678 config PANIC_ON_OOPS
 679         bool "Panic on Oops"
 680         help
 681           Say Y here to enable the kernel to panic when it oopses. This
 682           has the same effect as setting oops=panic on the kernel command
 683           line.
 684
 685           This feature is useful to ensure that the kernel does not do
 686           anything erroneous after an oops which could result in data
 687           corruption or other issues.
 688
 689           Say N if unsure.
 690
 691 config PANIC_ON_OOPS_VALUE
 692         int
 693         range 0 1
 694         default 0 if !PANIC_ON_OOPS
 695         default 1 if PANIC_ON_OOPS
 696
 697 config DETECT_HUNG_TASK
 698         bool "Detect Hung Tasks"
 699         depends on DEBUG_KERNEL
 700         default LOCKUP_DETECTOR
 701         help
 702           Say Y here to enable the kernel to detect "hung tasks",
 703           which are bugs that cause the task to be stuck in
 704           uninterruptible "D" state indefinitiley.
 705
 706           When a hung task is detected, the kernel will print the
 707           current stack trace (which you should report), but the
 708           task will stay in uninterruptible state. If lockdep is
 709           enabled then all held locks will also be reported. This
 710           feature has negligible overhead.
 711
 712 config DEFAULT_HUNG_TASK_TIMEOUT
 713         int "Default timeout for hung task detection (in seconds)"
 714         depends on DETECT_HUNG_TASK
 715         default 120
 716         help
 717           This option controls the default timeout (in seconds) used
 718           to determine when a task has become non-responsive and should
 719           be considered hung.
 720
 721           It can be adjusted at runtime via the kernel.hung_task_timeout_secs
 722           sysctl or by writing a value to
 723           /proc/sys/kernel/hung_task_timeout_secs.
 724
 725           A timeout of 0 disables the check.  The default is two minutes.
 726           Keeping the default should be fine in most cases.
 727
 728 config BOOTPARAM_HUNG_TASK_PANIC
 729         bool "Panic (Reboot) On Hung Tasks"
 730         depends on DETECT_HUNG_TASK
 731         help
 732           Say Y here to enable the kernel to panic on "hung tasks",
 733           which are bugs that cause the kernel to leave a task stuck
 734           in uninterruptible "D" state.
 735
 736           The panic can be used in combination with panic_timeout,
 737           to cause the system to reboot automatically after a
 738           hung task has been detected. This feature is useful for
 739           high-availability systems that have uptime guarantees and
 740           where a hung tasks must be resolved ASAP.
 741
 742           Say N if unsure.
 743
 744 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
 745         int
 746         depends on DETECT_HUNG_TASK
 747         range 0 1
 748         default 0 if !BOOTPARAM_HUNG_TASK_PANIC
 749         default 1 if BOOTPARAM_HUNG_TASK_PANIC
 750
 751 config SCHED_DEBUG
 752         bool "Collect scheduler debugging info"
 753         depends on DEBUG_KERNEL && PROC_FS
 754         default y
 755         help
 756           If you say Y here, the /proc/sched_debug file will be provided
 757           that can help debug the scheduler. The runtime overhead of this
 758           option is minimal.
 759
 760 config SCHEDSTATS
 761         bool "Collect scheduler statistics"
 762         depends on DEBUG_KERNEL && PROC_FS
 763         help
 764           If you say Y here, additional code will be inserted into the
 765           scheduler and related routines to collect statistics about
 766           scheduler behavior and provide them in /proc/schedstat.  These
 767           stats may be useful for both tuning and debugging the scheduler
 768           If you aren't debugging the scheduler or trying to tune a specific
 769           application, you can say N to avoid the very slight overhead
 770           this adds.
 771
 772 config TIMER_STATS
 773         bool "Collect kernel timers statistics"
 774         depends on DEBUG_KERNEL && PROC_FS
 775         help
 776           If you say Y here, additional code will be inserted into the
 777           timer routines to collect statistics about kernel timers being
 778           reprogrammed. The statistics can be read from /proc/timer_stats.
 779           The statistics collection is started by writing 1 to /proc/timer_stats,
 780           writing 0 stops it. This feature is useful to collect information
 781           about timer usage patterns in kernel and userspace. This feature
 782           is lightweight if enabled in the kernel config but not activated
 783           (it defaults to deactivated on bootup and will only be activated
 784           if some application like powertop activates it explicitly).
 785
 786 config DEBUG_PREEMPT
 787         bool "Debug preemptible kernel"
 788         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 789         default y
 790         help
 791           If you say Y here then the kernel will use a debug variant of the
 792           commonly used smp_processor_id() function and will print warnings
 793           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 794           will detect preemption count underflows.
 795
 796 menu "Lock Debugging (spinlocks, mutexes, etc...)"
 797
 798 config DEBUG_RT_MUTEXES
 799         bool "RT Mutex debugging, deadlock detection"
 800         depends on DEBUG_KERNEL && RT_MUTEXES
 801         help
 802          This allows rt mutex semantics violations and rt mutex related
 803          deadlocks (lockups) to be detected and reported automatically.
 804
 805 config DEBUG_PI_LIST
 806         bool
 807         default y
 808         depends on DEBUG_RT_MUTEXES
 809
 810 config RT_MUTEX_TESTER
 811         bool "Built-in scriptable tester for rt-mutexes"
 812         depends on DEBUG_KERNEL && RT_MUTEXES
 813         help
 814           This option enables a rt-mutex tester.
 815
 816 config DEBUG_SPINLOCK
 817         bool "Spinlock and rw-lock debugging: basic checks"
 818         depends on DEBUG_KERNEL
 819         select UNINLINE_SPIN_UNLOCK
 820         help
 821           Say Y here and build SMP to catch missing spinlock initialization
 822           and certain other kinds of spinlock errors commonly made.  This is
 823           best used in conjunction with the NMI watchdog so that spinlock
 824           deadlocks are also debuggable.
 825
 826 config DEBUG_MUTEXES
 827         bool "Mutex debugging: basic checks"
 828         depends on DEBUG_KERNEL
 829         help
 830          This feature allows mutex semantics violations to be detected and
 831          reported.
 832
 833 config DEBUG_LOCK_ALLOC
 834         bool "Lock debugging: detect incorrect freeing of live locks"
 835         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 836         select DEBUG_SPINLOCK
 837         select DEBUG_MUTEXES
 838         select LOCKDEP
 839         help
 840          This feature will check whether any held lock (spinlock, rwlock,
 841          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 842          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 843          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 844          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 845          held during task exit.
 846
 847 config PROVE_LOCKING
 848         bool "Lock debugging: prove locking correctness"
 849         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 850         select LOCKDEP
 851         select DEBUG_SPINLOCK
 852         select DEBUG_MUTEXES
 853         select DEBUG_LOCK_ALLOC
 854         select TRACE_IRQFLAGS
 855         default n
 856         help
 857          This feature enables the kernel to prove that all locking
 858          that occurs in the kernel runtime is mathematically
 859          correct: that under no circumstance could an arbitrary (and
 860          not yet triggered) combination of observed locking
 861          sequences (on an arbitrary number of CPUs, running an
 862          arbitrary number of tasks and interrupt contexts) cause a
 863          deadlock.
 864
 865          In short, this feature enables the kernel to report locking
 866          related deadlocks before they actually occur.
 867
 868          The proof does not depend on how hard and complex a
 869          deadlock scenario would be to trigger: how many
 870          participant CPUs, tasks and irq-contexts would be needed
 871          for it to trigger. The proof also does not depend on
 872          timing: if a race and a resulting deadlock is possible
 873          theoretically (no matter how unlikely the race scenario
 874          is), it will be proven so and will immediately be
 875          reported by the kernel (once the event is observed that
 876          makes the deadlock theoretically possible).
 877
 878          If a deadlock is impossible (i.e. the locking rules, as
 879          observed by the kernel, are mathematically correct), the
 880          kernel reports nothing.
 881
 882          NOTE: this feature can also be enabled for rwlocks, mutexes
 883          and rwsems - in which case all dependencies between these
 884          different locking variants are observed and mapped too, and
 885          the proof of observed correctness is also maintained for an
 886          arbitrary combination of these separate locking variants.
 887
 888          For more details, see Documentation/lockdep-design.txt.
 889
 890 config LOCKDEP
 891         bool
 892         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 893         select STACKTRACE
 894         select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
 895         select KALLSYMS
 896         select KALLSYMS_ALL
 897
 898 config LOCK_STAT
 899         bool "Lock usage statistics"
 900         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 901         select LOCKDEP
 902         select DEBUG_SPINLOCK
 903         select DEBUG_MUTEXES
 904         select DEBUG_LOCK_ALLOC
 905         default n
 906         help
 907          This feature enables tracking lock contention points
 908
 909          For more details, see Documentation/lockstat.txt
 910
 911          This also enables lock events required by "perf lock",
 912          subcommand of perf.
 913          If you want to use "perf lock", you also need to turn on
 914          CONFIG_EVENT_TRACING.
 915
 916          CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
 917          (CONFIG_LOCKDEP defines "acquire" and "release" events.)
 918
 919 config DEBUG_LOCKDEP
 920         bool "Lock dependency engine debugging"
 921         depends on DEBUG_KERNEL && LOCKDEP
 922         help
 923           If you say Y here, the lock dependency engine will do
 924           additional runtime checks to debug itself, at the price
 925           of more runtime overhead.
 926
 927 config DEBUG_ATOMIC_SLEEP
 928         bool "Sleep inside atomic section checking"
 929         select PREEMPT_COUNT
 930         depends on DEBUG_KERNEL
 931         help
 932           If you say Y here, various routines which may sleep will become very
 933           noisy if they are called inside atomic sections: when a spinlock is
 934           held, inside an rcu read side critical section, inside preempt disabled
 935           sections, inside an interrupt, etc...
 936
 937 config DEBUG_LOCKING_API_SELFTESTS
 938         bool "Locking API boot-time self-tests"
 939         depends on DEBUG_KERNEL
 940         help
 941           Say Y here if you want the kernel to run a short self-test during
 942           bootup. The self-test checks whether common types of locking bugs
 943           are detected by debugging mechanisms or not. (if you disable
 944           lock debugging then those bugs wont be detected of course.)
 945           The following locking APIs are covered: spinlocks, rwlocks,
 946           mutexes and rwsems.
 947
 948 endmenu # lock debugging
 949
 950 config TRACE_IRQFLAGS
 951         bool
 952         help
 953           Enables hooks to interrupt enabling and disabling for
 954           either tracing or lock debugging.
 955
 956 config STACKTRACE
 957         bool
 958         depends on STACKTRACE_SUPPORT
 959
 960 config DEBUG_KOBJECT
 961         bool "kobject debugging"
 962         depends on DEBUG_KERNEL
 963         help
 964           If you say Y here, some extra kobject debugging messages will be sent
 965           to the syslog.
 966
 967 config HAVE_DEBUG_BUGVERBOSE
 968         bool
 969
 970 config DEBUG_BUGVERBOSE
 971         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
 972         depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
 973         default y
 974         help
 975           Say Y here to make BUG() panics output the file name and line number
 976           of the BUG call as well as the EIP and oops trace.  This aids
 977           debugging but costs about 70-100K of memory.
 978
 979 config DEBUG_WRITECOUNT
 980         bool "Debug filesystem writers count"
 981         depends on DEBUG_KERNEL
 982         help
 983           Enable this to catch wrong use of the writers count in struct
 984           vfsmount.  This will increase the size of each file struct by
 985           32 bits.
 986
 987           If unsure, say N.
 988
 989 config DEBUG_LIST
 990         bool "Debug linked list manipulation"
 991         depends on DEBUG_KERNEL
 992         help
 993           Enable this to turn on extended checks in the linked-list
 994           walking routines.
 995
 996           If unsure, say N.
 997
 998 config DEBUG_SG
 999         bool "Debug SG table operations"
1000         depends on DEBUG_KERNEL
1001         help
1002           Enable this to turn on checks on scatter-gather tables. This can
1003           help find problems with drivers that do not properly initialize
1004           their sg tables.
1005
1006           If unsure, say N.
1007
1008 config DEBUG_NOTIFIERS
1009         bool "Debug notifier call chains"
1010         depends on DEBUG_KERNEL
1011         help
1012           Enable this to turn on sanity checking for notifier call chains.
1013           This is most useful for kernel developers to make sure that
1014           modules properly unregister themselves from notifier chains.
1015           This is a relatively cheap check but if you care about maximum
1016           performance, say N.
1017
1018 config DEBUG_CREDENTIALS
1019         bool "Debug credential management"
1020         depends on DEBUG_KERNEL
1021         help
1022           Enable this to turn on some debug checking for credential
1023           management.  The additional code keeps track of the number of
1024           pointers from task_structs to any given cred struct, and checks to
1025           see that this number never exceeds the usage count of the cred
1026           struct.
1027
1028           Furthermore, if SELinux is enabled, this also checks that the
1029           security pointer in the cred struct is never seen to be invalid.
1030
1031           If unsure, say N.
1032
1033 menu "RCU Debugging"
1034
1035 config PROVE_RCU
1036         bool "RCU debugging: prove RCU correctness"
1037         depends on PROVE_LOCKING
1038         default n
1039         help
1040          This feature enables lockdep extensions that check for correct
1041          use of RCU APIs.  This is currently under development.  Say Y
1042          if you want to debug RCU usage or help work on the PROVE_RCU
1043          feature.
1044
1045          Say N if you are unsure.
1046
1047 config PROVE_RCU_REPEATEDLY
1048         bool "RCU debugging: don't disable PROVE_RCU on first splat"
1049         depends on PROVE_RCU
1050         default n
1051         help
1052          By itself, PROVE_RCU will disable checking upon issuing the
1053          first warning (or "splat").  This feature prevents such
1054          disabling, allowing multiple RCU-lockdep warnings to be printed
1055          on a single reboot.
1056
1057          Say Y to allow multiple RCU-lockdep warnings per boot.
1058
1059          Say N if you are unsure.
1060
1061 config PROVE_RCU_DELAY
1062         bool "RCU debugging: preemptible RCU race provocation"
1063         depends on DEBUG_KERNEL && PREEMPT_RCU
1064         default n
1065         help
1066          There is a class of races that involve an unlikely preemption
1067          of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
1068          been set to INT_MIN.  This feature inserts a delay at that
1069          point to increase the probability of these races.
1070
1071          Say Y to increase probability of preemption of __rcu_read_unlock().
1072
1073          Say N if you are unsure.
1074
1075 config SPARSE_RCU_POINTER
1076         bool "RCU debugging: sparse-based checks for pointer usage"
1077         default n
1078         help
1079          This feature enables the __rcu sparse annotation for
1080          RCU-protected pointers.  This annotation will cause sparse
1081          to flag any non-RCU used of annotated pointers.  This can be
1082          helpful when debugging RCU usage.  Please note that this feature
1083          is not intended to enforce code cleanliness; it is instead merely
1084          a debugging aid.
1085
1086          Say Y to make sparse flag questionable use of RCU-protected pointers
1087
1088          Say N if you are unsure.
1089
1090 config RCU_TORTURE_TEST
1091         tristate "torture tests for RCU"
1092         depends on DEBUG_KERNEL
1093         default n
1094         help
1095           This option provides a kernel module that runs torture tests
1096           on the RCU infrastructure.  The kernel module may be built
1097           after the fact on the running kernel to be tested, if desired.
1098
1099           Say Y here if you want RCU torture tests to be built into
1100           the kernel.
1101           Say M if you want the RCU torture tests to build as a module.
1102           Say N if you are unsure.
1103
1104 config RCU_TORTURE_TEST_RUNNABLE
1105         bool "torture tests for RCU runnable by default"
1106         depends on RCU_TORTURE_TEST = y
1107         default n
1108         help
1109           This option provides a way to build the RCU torture tests
1110           directly into the kernel without them starting up at boot
1111           time.  You can use /proc/sys/kernel/rcutorture_runnable
1112           to manually override this setting.  This /proc file is
1113           available only when the RCU torture tests have been built
1114           into the kernel.
1115
1116           Say Y here if you want the RCU torture tests to start during
1117           boot (you probably don't).
1118           Say N here if you want the RCU torture tests to start only
1119           after being manually enabled via /proc.
1120
1121 config RCU_CPU_STALL_TIMEOUT
1122         int "RCU CPU stall timeout in seconds"
1123         depends on RCU_STALL_COMMON
1124         range 3 300
1125         default 21
1126         help
1127           If a given RCU grace period extends more than the specified
1128           number of seconds, a CPU stall warning is printed.  If the
1129           RCU grace period persists, additional CPU stall warnings are
1130           printed at more widely spaced intervals.
1131
1132 config RCU_CPU_STALL_VERBOSE
1133         bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
1134         depends on TREE_PREEMPT_RCU
1135         default y
1136         help
1137           This option causes RCU to printk detailed per-task information
1138           for any tasks that are stalling the current RCU grace period.
1139
1140           Say N if you are unsure.
1141
1142           Say Y if you want to enable such checks.
1143
1144 config RCU_CPU_STALL_INFO
1145         bool "Print additional diagnostics on RCU CPU stall"
1146         depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1147         default n
1148         help
1149           For each stalled CPU that is aware of the current RCU grace
1150           period, print out additional per-CPU diagnostic information
1151           regarding scheduling-clock ticks, idle state, and,
1152           for RCU_FAST_NO_HZ kernels, idle-entry state.
1153
1154           Say N if you are unsure.
1155
1156           Say Y if you want to enable such diagnostics.
1157
1158 config RCU_TRACE
1159         bool "Enable tracing for RCU"
1160         depends on DEBUG_KERNEL
1161         select TRACE_CLOCK
1162         help
1163           This option provides tracing in RCU which presents stats
1164           in debugfs for debugging RCU implementation.
1165
1166           Say Y here if you want to enable RCU tracing
1167           Say N if you are unsure.
1168
1169 endmenu # "RCU Debugging"
1170
1171 config DEBUG_BLOCK_EXT_DEVT
1172         bool "Force extended block device numbers and spread them"
1173         depends on DEBUG_KERNEL
1174         depends on BLOCK
1175         default n
1176         help
1177           BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1178           SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1179           YOU ARE DOING.  Distros, please enable this and fix whatever
1180           is broken.
1181
1182           Conventionally, block device numbers are allocated from
1183           predetermined contiguous area.  However, extended block area
1184           may introduce non-contiguous block device numbers.  This
1185           option forces most block device numbers to be allocated from
1186           the extended space and spreads them to discover kernel or
1187           userland code paths which assume predetermined contiguous
1188           device number allocation.
1189
1190           Note that turning on this debug option shuffles all the
1191           device numbers for all IDE and SCSI devices including libata
1192           ones, so root partition specified using device number
1193           directly (via rdev or root=MAJ:MIN) won't work anymore.
1194           Textual device names (root=/dev/sdXn) will continue to work.
1195
1196           Say N if you are unsure.
1197
1198 config NOTIFIER_ERROR_INJECTION
1199         tristate "Notifier error injection"
1200         depends on DEBUG_KERNEL
1201         select DEBUG_FS
1202         help
1203           This option provides the ability to inject artificial errors to
1204           specified notifier chain callbacks. It is useful to test the error
1205           handling of notifier call chain failures.
1206
1207           Say N if unsure.
1208
1209 config CPU_NOTIFIER_ERROR_INJECT
1210         tristate "CPU notifier error injection module"
1211         depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1212         help
1213           This option provides a kernel module that can be used to test
1214           the error handling of the cpu notifiers by injecting artificial
1215           errors to CPU notifier chain callbacks.  It is controlled through
1216           debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1217
1218           If the notifier call chain should be failed with some events
1219           notified, write the error code to "actions/<notifier event>/error".
1220
1221           Example: Inject CPU offline error (-1 == -EPERM)
1222
1223           # cd /sys/kernel/debug/notifier-error-inject/cpu
1224           # echo -1 > actions/CPU_DOWN_PREPARE/error
1225           # echo 0 > /sys/devices/system/cpu/cpu1/online
1226           bash: echo: write error: Operation not permitted
1227
1228           To compile this code as a module, choose M here: the module will
1229           be called cpu-notifier-error-inject.
1230
1231           If unsure, say N.
1232
1233 config PM_NOTIFIER_ERROR_INJECT
1234         tristate "PM notifier error injection module"
1235         depends on PM && NOTIFIER_ERROR_INJECTION
1236         default m if PM_DEBUG
1237         help
1238           This option provides the ability to inject artificial errors to
1239           PM notifier chain callbacks.  It is controlled through debugfs
1240           interface /sys/kernel/debug/notifier-error-inject/pm
1241
1242           If the notifier call chain should be failed with some events
1243           notified, write the error code to "actions/<notifier event>/error".
1244
1245           Example: Inject PM suspend error (-12 = -ENOMEM)
1246
1247           # cd /sys/kernel/debug/notifier-error-inject/pm/
1248           # echo -12 > actions/PM_SUSPEND_PREPARE/error
1249           # echo mem > /sys/power/state
1250           bash: echo: write error: Cannot allocate memory
1251
1252           To compile this code as a module, choose M here: the module will
1253           be called pm-notifier-error-inject.
1254
1255           If unsure, say N.
1256
1257 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1258         tristate "OF reconfig notifier error injection module"
1259         depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1260         help
1261           This option provides the ability to inject artificial errors to
1262           OF reconfig notifier chain callbacks.  It is controlled
1263           through debugfs interface under
1264           /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1265
1266           If the notifier call chain should be failed with some events
1267           notified, write the error code to "actions/<notifier event>/error".
1268
1269           To compile this code as a module, choose M here: the module will
1270           be called of-reconfig-notifier-error-inject.
1271
1272           If unsure, say N.
1273
1274 config FAULT_INJECTION
1275         bool "Fault-injection framework"
1276         depends on DEBUG_KERNEL
1277         help
1278           Provide fault-injection framework.
1279           For more details, see Documentation/fault-injection/.
1280
1281 config FAILSLAB
1282         bool "Fault-injection capability for kmalloc"
1283         depends on FAULT_INJECTION
1284         depends on SLAB || SLUB
1285         help
1286           Provide fault-injection capability for kmalloc.
1287
1288 config FAIL_PAGE_ALLOC
1289         bool "Fault-injection capabilitiy for alloc_pages()"
1290         depends on FAULT_INJECTION
1291         help
1292           Provide fault-injection capability for alloc_pages().
1293
1294 config FAIL_MAKE_REQUEST
1295         bool "Fault-injection capability for disk IO"
1296         depends on FAULT_INJECTION && BLOCK
1297         help
1298           Provide fault-injection capability for disk IO.
1299
1300 config FAIL_IO_TIMEOUT
1301         bool "Fault-injection capability for faking disk interrupts"
1302         depends on FAULT_INJECTION && BLOCK
1303         help
1304           Provide fault-injection capability on end IO handling. This
1305           will make the block layer "forget" an interrupt as configured,
1306           thus exercising the error handling.
1307
1308           Only works with drivers that use the generic timeout handling,
1309           for others it wont do anything.
1310
1311 config FAIL_MMC_REQUEST
1312         bool "Fault-injection capability for MMC IO"
1313         select DEBUG_FS
1314         depends on FAULT_INJECTION && MMC
1315         help
1316           Provide fault-injection capability for MMC IO.
1317           This will make the mmc core return data errors. This is
1318           useful to test the error handling in the mmc block device
1319           and to test how the mmc host driver handles retries from
1320           the block device.
1321
1322 config FAULT_INJECTION_DEBUG_FS
1323         bool "Debugfs entries for fault-injection capabilities"
1324         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1325         help
1326           Enable configuration of fault-injection capabilities via debugfs.
1327
1328 config FAULT_INJECTION_STACKTRACE_FILTER
1329         bool "stacktrace filter for fault-injection capabilities"
1330         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1331         depends on !X86_64
1332         select STACKTRACE
1333         select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1334         help
1335           Provide stacktrace filter for fault-injection capabilities
1336
1337 config LATENCYTOP
1338         bool "Latency measuring infrastructure"
1339         depends on HAVE_LATENCYTOP_SUPPORT
1340         depends on DEBUG_KERNEL
1341         depends on STACKTRACE_SUPPORT
1342         depends on PROC_FS
1343         select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1344         select KALLSYMS
1345         select KALLSYMS_ALL
1346         select STACKTRACE
1347         select SCHEDSTATS
1348         select SCHED_DEBUG
1349         help
1350           Enable this option if you want to use the LatencyTOP tool
1351           to find out which userspace is blocking on what kernel operations.
1352
1353 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1354         bool
1355
1356 config DEBUG_STRICT_USER_COPY_CHECKS
1357         bool "Strict user copy size checks"
1358         depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1359         depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1360         help
1361           Enabling this option turns a certain set of sanity checks for user
1362           copy operations into compile time failures.
1363
1364           The copy_from_user() etc checks are there to help test if there
1365           are sufficient security checks on the length argument of
1366           the copy operation, by having gcc prove that the argument is
1367           within bounds.
1368
1369           If unsure, say N.
1370
1371 source kernel/trace/Kconfig
1372
1373 menu "Runtime Testing"
1374
1375 config LKDTM
1376         tristate "Linux Kernel Dump Test Tool Module"
1377         depends on DEBUG_FS
1378         depends on BLOCK
1379         default n
1380         help
1381         This module enables testing of the different dumping mechanisms by
1382         inducing system failures at predefined crash points.
1383         If you don't need it: say N
1384         Choose M here to compile this code as a module. The module will be
1385         called lkdtm.
1386
1387         Documentation on how to use the module can be found in
1388         Documentation/fault-injection/provoke-crashes.txt
1389
1390 config TEST_LIST_SORT
1391         bool "Linked list sorting test"
1392         depends on DEBUG_KERNEL
1393         help
1394           Enable this to turn on 'list_sort()' function test. This test is
1395           executed only once during system boot, so affects only boot time.
1396
1397           If unsure, say N.
1398
1399 config KPROBES_SANITY_TEST
1400         bool "Kprobes sanity tests"
1401         depends on DEBUG_KERNEL
1402         depends on KPROBES
1403         default n
1404         help
1405           This option provides for testing basic kprobes functionality on
1406           boot. A sample kprobe, jprobe and kretprobe are inserted and
1407           verified for functionality.
1408
1409           Say N if you are unsure.
1410
1411 config BACKTRACE_SELF_TEST
1412         tristate "Self test for the backtrace code"
1413         depends on DEBUG_KERNEL
1414         default n
1415         help
1416           This option provides a kernel module that can be used to test
1417           the kernel stack backtrace code. This option is not useful
1418           for distributions or general kernels, but only for kernel
1419           developers working on architecture code.
1420
1421           Note that if you want to also test saved backtraces, you will
1422           have to enable STACKTRACE as well.
1423
1424           Say N if you are unsure.
1425
1426 config RBTREE_TEST
1427         tristate "Red-Black tree test"
1428         depends on m && DEBUG_KERNEL
1429         help
1430           A benchmark measuring the performance of the rbtree library.
1431           Also includes rbtree invariant checks.
1432
1433 config INTERVAL_TREE_TEST
1434         tristate "Interval tree test"
1435         depends on m && DEBUG_KERNEL
1436         help
1437           A benchmark measuring the performance of the interval tree library
1438
1439 config ATOMIC64_SELFTEST
1440         bool "Perform an atomic64_t self-test at boot"
1441         help
1442           Enable this option to test the atomic64_t functions at boot.
1443
1444           If unsure, say N.
1445
1446 config ASYNC_RAID6_TEST
1447         tristate "Self test for hardware accelerated raid6 recovery"
1448         depends on ASYNC_RAID6_RECOV
1449         select ASYNC_MEMCPY
1450         ---help---
1451           This is a one-shot self test that permutes through the
1452           recovery of all the possible two disk failure scenarios for a
1453           N-disk array.  Recovery is performed with the asynchronous
1454           raid6 recovery routines, and will optionally use an offload
1455           engine if one is available.
1456
1457           If unsure, say N.
1458
1459 config TEST_STRING_HELPERS
1460         tristate "Test functions located in the string_helpers module at runtime"
1461
1462 config TEST_KSTRTOX
1463         tristate "Test kstrto*() family of functions at runtime"
1464
1465 endmenu # runtime tests
1466
1467 config PROVIDE_OHCI1394_DMA_INIT
1468         bool "Remote debugging over FireWire early on boot"
1469         depends on PCI && X86
1470         help
1471           If you want to debug problems which hang or crash the kernel early
1472           on boot and the crashing machine has a FireWire port, you can use
1473           this feature to remotely access the memory of the crashed machine
1474           over FireWire. This employs remote DMA as part of the OHCI1394
1475           specification which is now the standard for FireWire controllers.
1476
1477           With remote DMA, you can monitor the printk buffer remotely using
1478           firescope and access all memory below 4GB using fireproxy from gdb.
1479           Even controlling a kernel debugger is possible using remote DMA.
1480
1481           Usage:
1482
1483           If ohci1394_dma=early is used as boot parameter, it will initialize
1484           all OHCI1394 controllers which are found in the PCI config space.
1485
1486           As all changes to the FireWire bus such as enabling and disabling
1487           devices cause a bus reset and thereby disable remote DMA for all
1488           devices, be sure to have the cable plugged and FireWire enabled on
1489           the debugging host before booting the debug target for debugging.
1490
1491           This code (~1k) is freed after boot. By then, the firewire stack
1492           in charge of the OHCI-1394 controllers should be used instead.
1493
1494           See Documentation/debugging-via-ohci1394.txt for more information.
1495
1496 config FIREWIRE_OHCI_REMOTE_DMA
1497         bool "Remote debugging over FireWire with firewire-ohci"
1498         depends on FIREWIRE_OHCI
1499         help
1500           This option lets you use the FireWire bus for remote debugging
1501           with help of the firewire-ohci driver. It enables unfiltered
1502           remote DMA in firewire-ohci.
1503           See Documentation/debugging-via-ohci1394.txt for more information.
1504
1505           If unsure, say N.
1506
1507 config BUILD_DOCSRC
1508         bool "Build targets in Documentation/ tree"
1509         depends on HEADERS_CHECK
1510         help
1511           This option attempts to build objects from the source files in the
1512           kernel Documentation/ tree.
1513
1514           Say N if you are unsure.
1515
1516 config DMA_API_DEBUG
1517         bool "Enable debugging of DMA-API usage"
1518         depends on HAVE_DMA_API_DEBUG
1519         help
1520           Enable this option to debug the use of the DMA API by device drivers.
1521           With this option you will be able to detect common bugs in device
1522           drivers like double-freeing of DMA mappings or freeing mappings that
1523           were never allocated.
1524           This option causes a performance degredation.  Use only if you want
1525           to debug device drivers. If unsure, say N.
1526
1527 source "samples/Kconfig"
1528
1529 source "lib/Kconfig.kgdb"
1530