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_MUST_CHECK
  13         bool "Enable __must_check logic"
  14         default y
  15         help
  16           Enable the __must_check logic in the kernel build.  Disable this to
  17           suppress the "warning: ignoring return value of 'foo', declared with
  18           attribute warn_unused_result" messages.
  19
  20 config MAGIC_SYSRQ
  21         bool "Magic SysRq key"
  22         depends on !UML
  23         help
  24           If you say Y here, you will have some control over the system even
  25           if the system crashes for example during kernel debugging (e.g., you
  26           will be able to flush the buffer cache to disk, reboot the system
  27           immediately or dump some status information). This is accomplished
  28           by pressing various keys while holding SysRq (Alt+PrintScreen). It
  29           also works on a serial console (on PC hardware at least), if you
  30           send a BREAK and then within 5 seconds a command keypress. The
  31           keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  32           unless you really know what this hack does.
  33
  34 config UNUSED_SYMBOLS
  35         bool "Enable unused/obsolete exported symbols"
  36         default y if X86
  37         help
  38           Unused but exported symbols make the kernel needlessly bigger.  For
  39           that reason most of these unused exports will soon be removed.  This
  40           option is provided temporarily to provide a transition period in case
  41           some external kernel module needs one of these symbols anyway. If you
  42           encounter such a case in your module, consider if you are actually
  43           using the right API.  (rationale: since nobody in the kernel is using
  44           this in a module, there is a pretty good chance it's actually the
  45           wrong interface to use).  If you really need the symbol, please send a
  46           mail to the linux kernel mailing list mentioning the symbol and why
  47           you really need it, and what the merge plan to the mainline kernel for
  48           your module is.
  49
  50 config DEBUG_FS
  51         bool "Debug Filesystem"
  52         depends on SYSFS
  53         help
  54           debugfs is a virtual file system that kernel developers use to put
  55           debugging files into.  Enable this option to be able to read and
  56           write to these files.
  57
  58           If unsure, say N.
  59
  60 config HEADERS_CHECK
  61         bool "Run 'make headers_check' when building vmlinux"
  62         depends on !UML
  63         help
  64           This option will extract the user-visible kernel headers whenever
  65           building the kernel, and will run basic sanity checks on them to
  66           ensure that exported files do not attempt to include files which
  67           were not exported, etc.
  68
  69           If you're making modifications to header files which are
  70           relevant for userspace, say 'Y', and check the headers
  71           exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  72           your build tree), to make sure they're suitable.
  73
  74 config DEBUG_KERNEL
  75         bool "Kernel debugging"
  76         help
  77           Say Y here if you are developing drivers or trying to debug and
  78           identify kernel problems.
  79
  80 config DEBUG_SHIRQ
  81         bool "Debug shared IRQ handlers"
  82         depends on DEBUG_KERNEL && GENERIC_HARDIRQS
  83         help
  84           Enable this to generate a spurious interrupt as soon as a shared
  85           interrupt handler is registered, and just before one is deregistered.
  86           Drivers ought to be able to handle interrupts coming in at those
  87           points; some don't and need to be caught.
  88
  89 config DETECT_SOFTLOCKUP
  90         bool "Detect Soft Lockups"
  91         depends on DEBUG_KERNEL && !S390
  92         default y
  93         help
  94           Say Y here to enable the kernel to detect "soft lockups",
  95           which are bugs that cause the kernel to loop in kernel
  96           mode for more than 10 seconds, without giving other tasks a
  97           chance to run.
  98
  99           When a soft-lockup is detected, the kernel will print the
 100           current stack trace (which you should report), but the
 101           system will stay locked up. This feature has negligible
 102           overhead.
 103
 104           (Note that "hard lockups" are separate type of bugs that
 105            can be detected via the NMI-watchdog, on platforms that
 106            support it.)
 107
 108 config SCHED_DEBUG
 109         bool "Collect scheduler debugging info"
 110         depends on DEBUG_KERNEL && PROC_FS
 111         default y
 112         help
 113           If you say Y here, the /proc/sched_debug file will be provided
 114           that can help debug the scheduler. The runtime overhead of this
 115           option is minimal.
 116
 117 config SCHEDSTATS
 118         bool "Collect scheduler statistics"
 119         depends on DEBUG_KERNEL && PROC_FS
 120         help
 121           If you say Y here, additional code will be inserted into the
 122           scheduler and related routines to collect statistics about
 123           scheduler behavior and provide them in /proc/schedstat.  These
 124           stats may be useful for both tuning and debugging the scheduler
 125           If you aren't debugging the scheduler or trying to tune a specific
 126           application, you can say N to avoid the very slight overhead
 127           this adds.
 128
 129 config TIMER_STATS
 130         bool "Collect kernel timers statistics"
 131         depends on DEBUG_KERNEL && PROC_FS
 132         help
 133           If you say Y here, additional code will be inserted into the
 134           timer routines to collect statistics about kernel timers being
 135           reprogrammed. The statistics can be read from /proc/timer_stats.
 136           The statistics collection is started by writing 1 to /proc/timer_stats,
 137           writing 0 stops it. This feature is useful to collect information
 138           about timer usage patterns in kernel and userspace. This feature
 139           is lightweight if enabled in the kernel config but not activated
 140           (it defaults to deactivated on bootup and will only be activated
 141           if some application like powertop activates it explicitly).
 142
 143 config DEBUG_SLAB
 144         bool "Debug slab memory allocations"
 145         depends on DEBUG_KERNEL && SLAB
 146         help
 147           Say Y here to have the kernel do limited verification on memory
 148           allocation as well as poisoning memory on free to catch use of freed
 149           memory. This can make kmalloc/kfree-intensive workloads much slower.
 150
 151 config DEBUG_SLAB_LEAK
 152         bool "Memory leak debugging"
 153         depends on DEBUG_SLAB
 154
 155 config SLUB_DEBUG_ON
 156         bool "SLUB debugging on by default"
 157         depends on SLUB && SLUB_DEBUG
 158         default n
 159         help
 160           Boot with debugging on by default. SLUB boots by default with
 161           the runtime debug capabilities switched off. Enabling this is
 162           equivalent to specifying the "slub_debug" parameter on boot.
 163           There is no support for more fine grained debug control like
 164           possible with slub_debug=xxx. SLUB debugging may be switched
 165           off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
 166           "slub_debug=-".
 167
 168 config DEBUG_PREEMPT
 169         bool "Debug preemptible kernel"
 170         depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
 171         default y
 172         help
 173           If you say Y here then the kernel will use a debug variant of the
 174           commonly used smp_processor_id() function and will print warnings
 175           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 176           will detect preemption count underflows.
 177
 178 config DEBUG_RT_MUTEXES
 179         bool "RT Mutex debugging, deadlock detection"
 180         depends on DEBUG_KERNEL && RT_MUTEXES
 181         help
 182          This allows rt mutex semantics violations and rt mutex related
 183          deadlocks (lockups) to be detected and reported automatically.
 184
 185 config DEBUG_PI_LIST
 186         bool
 187         default y
 188         depends on DEBUG_RT_MUTEXES
 189
 190 config RT_MUTEX_TESTER
 191         bool "Built-in scriptable tester for rt-mutexes"
 192         depends on DEBUG_KERNEL && RT_MUTEXES
 193         help
 194           This option enables a rt-mutex tester.
 195
 196 config DEBUG_SPINLOCK
 197         bool "Spinlock and rw-lock debugging: basic checks"
 198         depends on DEBUG_KERNEL
 199         help
 200           Say Y here and build SMP to catch missing spinlock initialization
 201           and certain other kinds of spinlock errors commonly made.  This is
 202           best used in conjunction with the NMI watchdog so that spinlock
 203           deadlocks are also debuggable.
 204
 205 config DEBUG_MUTEXES
 206         bool "Mutex debugging: basic checks"
 207         depends on DEBUG_KERNEL
 208         help
 209          This feature allows mutex semantics violations to be detected and
 210          reported.
 211
 212 config DEBUG_SEMAPHORE
 213         bool "Semaphore debugging"
 214         depends on DEBUG_KERNEL
 215         depends on ALPHA || FRV
 216         default n
 217         help
 218           If you say Y here then semaphore processing will issue lots of
 219           verbose debugging messages.  If you suspect a semaphore problem or a
 220           kernel hacker asks for this option then say Y.  Otherwise say N.
 221
 222 config DEBUG_LOCK_ALLOC
 223         bool "Lock debugging: detect incorrect freeing of live locks"
 224         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 225         select DEBUG_SPINLOCK
 226         select DEBUG_MUTEXES
 227         select LOCKDEP
 228         help
 229          This feature will check whether any held lock (spinlock, rwlock,
 230          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 231          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 232          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 233          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 234          held during task exit.
 235
 236 config PROVE_LOCKING
 237         bool "Lock debugging: prove locking correctness"
 238         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 239         select LOCKDEP
 240         select DEBUG_SPINLOCK
 241         select DEBUG_MUTEXES
 242         select DEBUG_LOCK_ALLOC
 243         default n
 244         help
 245          This feature enables the kernel to prove that all locking
 246          that occurs in the kernel runtime is mathematically
 247          correct: that under no circumstance could an arbitrary (and
 248          not yet triggered) combination of observed locking
 249          sequences (on an arbitrary number of CPUs, running an
 250          arbitrary number of tasks and interrupt contexts) cause a
 251          deadlock.
 252
 253          In short, this feature enables the kernel to report locking
 254          related deadlocks before they actually occur.
 255
 256          The proof does not depend on how hard and complex a
 257          deadlock scenario would be to trigger: how many
 258          participant CPUs, tasks and irq-contexts would be needed
 259          for it to trigger. The proof also does not depend on
 260          timing: if a race and a resulting deadlock is possible
 261          theoretically (no matter how unlikely the race scenario
 262          is), it will be proven so and will immediately be
 263          reported by the kernel (once the event is observed that
 264          makes the deadlock theoretically possible).
 265
 266          If a deadlock is impossible (i.e. the locking rules, as
 267          observed by the kernel, are mathematically correct), the
 268          kernel reports nothing.
 269
 270          NOTE: this feature can also be enabled for rwlocks, mutexes
 271          and rwsems - in which case all dependencies between these
 272          different locking variants are observed and mapped too, and
 273          the proof of observed correctness is also maintained for an
 274          arbitrary combination of these separate locking variants.
 275
 276          For more details, see Documentation/lockdep-design.txt.
 277
 278 config LOCKDEP
 279         bool
 280         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 281         select STACKTRACE
 282         select FRAME_POINTER if !X86 && !MIPS
 283         select KALLSYMS
 284         select KALLSYMS_ALL
 285
 286 config LOCK_STAT
 287         bool "Lock usage statistics"
 288         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 289         select LOCKDEP
 290         select DEBUG_SPINLOCK
 291         select DEBUG_MUTEXES
 292         select DEBUG_LOCK_ALLOC
 293         default n
 294         help
 295          This feature enables tracking lock contention points
 296
 297          For more details, see Documentation/lockstat.txt
 298
 299 config DEBUG_LOCKDEP
 300         bool "Lock dependency engine debugging"
 301         depends on DEBUG_KERNEL && LOCKDEP
 302         help
 303           If you say Y here, the lock dependency engine will do
 304           additional runtime checks to debug itself, at the price
 305           of more runtime overhead.
 306
 307 config TRACE_IRQFLAGS
 308         depends on DEBUG_KERNEL
 309         bool
 310         default y
 311         depends on TRACE_IRQFLAGS_SUPPORT
 312         depends on PROVE_LOCKING
 313
 314 config DEBUG_SPINLOCK_SLEEP
 315         bool "Spinlock debugging: sleep-inside-spinlock checking"
 316         depends on DEBUG_KERNEL
 317         help
 318           If you say Y here, various routines which may sleep will become very
 319           noisy if they are called with a spinlock held.
 320
 321 config DEBUG_LOCKING_API_SELFTESTS
 322         bool "Locking API boot-time self-tests"
 323         depends on DEBUG_KERNEL
 324         help
 325           Say Y here if you want the kernel to run a short self-test during
 326           bootup. The self-test checks whether common types of locking bugs
 327           are detected by debugging mechanisms or not. (if you disable
 328           lock debugging then those bugs wont be detected of course.)
 329           The following locking APIs are covered: spinlocks, rwlocks,
 330           mutexes and rwsems.
 331
 332 config STACKTRACE
 333         bool
 334         depends on DEBUG_KERNEL
 335         depends on STACKTRACE_SUPPORT
 336
 337 config DEBUG_KOBJECT
 338         bool "kobject debugging"
 339         depends on DEBUG_KERNEL
 340         help
 341           If you say Y here, some extra kobject debugging messages will be sent
 342           to the syslog.
 343
 344 config DEBUG_HIGHMEM
 345         bool "Highmem debugging"
 346         depends on DEBUG_KERNEL && HIGHMEM
 347         help
 348           This options enables addition error checking for high memory systems.
 349           Disable for production systems.
 350
 351 config DEBUG_BUGVERBOSE
 352         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 353         depends on BUG
 354         depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BFIN
 355         default !EMBEDDED
 356         help
 357           Say Y here to make BUG() panics output the file name and line number
 358           of the BUG call as well as the EIP and oops trace.  This aids
 359           debugging but costs about 70-100K of memory.
 360
 361 config DEBUG_INFO
 362         bool "Compile the kernel with debug info"
 363         depends on DEBUG_KERNEL
 364         help
 365           If you say Y here the resulting kernel image will include
 366           debugging info resulting in a larger kernel image.
 367           This adds debug symbols to the kernel and modules (gcc -g), and
 368           is needed if you intend to use kernel crashdump or binary object
 369           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 370           Say Y here only if you plan to debug the kernel.
 371
 372           If unsure, say N.
 373
 374 config DEBUG_VM
 375         bool "Debug VM"
 376         depends on DEBUG_KERNEL
 377         help
 378           Enable this to turn on extended checks in the virtual-memory system
 379           that may impact performance.
 380
 381           If unsure, say N.
 382
 383 config DEBUG_LIST
 384         bool "Debug linked list manipulation"
 385         depends on DEBUG_KERNEL
 386         help
 387           Enable this to turn on extended checks in the linked-list
 388           walking routines.
 389
 390           If unsure, say N.
 391
 392 config FRAME_POINTER
 393         bool "Compile the kernel with frame pointers"
 394         depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BFIN)
 395         default y if DEBUG_INFO && UML
 396         help
 397           If you say Y here the resulting kernel image will be slightly larger
 398           and slower, but it might give very useful debugging information on
 399           some architectures or if you use external debuggers.
 400           If you don't debug the kernel, you can say N.
 401
 402 config FORCED_INLINING
 403         bool "Force gcc to inline functions marked 'inline'"
 404         depends on DEBUG_KERNEL
 405         default y
 406         help
 407           This option determines if the kernel forces gcc to inline the functions
 408           developers have marked 'inline'. Doing so takes away freedom from gcc to
 409           do what it thinks is best, which is desirable for the gcc 3.x series of
 410           compilers. The gcc 4.x series have a rewritten inlining algorithm and
 411           disabling this option will generate a smaller kernel there. Hopefully
 412           this algorithm is so good that allowing gcc4 to make the decision can
 413           become the default in the future, until then this option is there to
 414           test gcc for this.
 415
 416 config BOOT_PRINTK_DELAY
 417         bool "Delay each boot printk message by N milliseconds"
 418         depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
 419         help
 420           This build option allows you to read kernel boot messages
 421           by inserting a short delay after each one.  The delay is
 422           specified in milliseconds on the kernel command line,
 423           using "boot_delay=N".
 424
 425           It is likely that you would also need to use "lpj=M" to preset
 426           the "loops per jiffie" value.
 427           See a previous boot log for the "lpj" value to use for your
 428           system, and then set "lpj=M" before setting "boot_delay=N".
 429           NOTE:  Using this option may adversely affect SMP systems.
 430           I.e., processors other than the first one may not boot up.
 431           BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
 432           what it believes to be lockup conditions.
 433
 434 config RCU_TORTURE_TEST
 435         tristate "torture tests for RCU"
 436         depends on DEBUG_KERNEL
 437         depends on m
 438         default n
 439         help
 440           This option provides a kernel module that runs torture tests
 441           on the RCU infrastructure.  The kernel module may be built
 442           after the fact on the running kernel to be tested, if desired.
 443
 444           Say M if you want the RCU torture tests to build as a module.
 445           Say N if you are unsure.
 446
 447 config LKDTM
 448         tristate "Linux Kernel Dump Test Tool Module"
 449         depends on DEBUG_KERNEL
 450         depends on KPROBES
 451         default n
 452         help
 453         This module enables testing of the different dumping mechanisms by
 454         inducing system failures at predefined crash points.
 455         If you don't need it: say N
 456         Choose M here to compile this code as a module. The module will be
 457         called lkdtm.
 458
 459         Documentation on how to use the module can be found in
 460         drivers/misc/lkdtm.c
 461
 462 config FAULT_INJECTION
 463         bool "Fault-injection framework"
 464         depends on DEBUG_KERNEL
 465         help
 466           Provide fault-injection framework.
 467           For more details, see Documentation/fault-injection/.
 468
 469 config FAILSLAB
 470         bool "Fault-injection capability for kmalloc"
 471         depends on FAULT_INJECTION
 472         help
 473           Provide fault-injection capability for kmalloc.
 474
 475 config FAIL_PAGE_ALLOC
 476         bool "Fault-injection capabilitiy for alloc_pages()"
 477         depends on FAULT_INJECTION
 478         help
 479           Provide fault-injection capability for alloc_pages().
 480
 481 config FAIL_MAKE_REQUEST
 482         bool "Fault-injection capability for disk IO"
 483         depends on FAULT_INJECTION
 484         help
 485           Provide fault-injection capability for disk IO.
 486
 487 config FAULT_INJECTION_DEBUG_FS
 488         bool "Debugfs entries for fault-injection capabilities"
 489         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 490         help
 491           Enable configuration of fault-injection capabilities via debugfs.
 492
 493 config FAULT_INJECTION_STACKTRACE_FILTER
 494         bool "stacktrace filter for fault-injection capabilities"
 495         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 496         depends on !X86_64
 497         select STACKTRACE
 498         select FRAME_POINTER
 499         help
 500           Provide stacktrace filter for fault-injection capabilities