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 LOG_BUF_SHIFT
  90         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
  91         range 12 21
  92         default 17 if S390 || LOCKDEP
  93         default 16 if X86_NUMAQ || IA64
  94         default 15 if SMP
  95         default 14
  96         help
  97           Select kernel log buffer size as a power of 2.
  98           Defaults and Examples:
  99                      17 => 128 KB for S/390
 100                      16 => 64 KB for x86 NUMAQ or IA-64
 101                      15 => 32 KB for SMP
 102                      14 => 16 KB for uniprocessor
 103                      13 =>  8 KB
 104                      12 =>  4 KB
 105
 106 config DETECT_SOFTLOCKUP
 107         bool "Detect Soft Lockups"
 108         depends on DEBUG_KERNEL && !S390
 109         default y
 110         help
 111           Say Y here to enable the kernel to detect "soft lockups",
 112           which are bugs that cause the kernel to loop in kernel
 113           mode for more than 10 seconds, without giving other tasks a
 114           chance to run.
 115
 116           When a soft-lockup is detected, the kernel will print the
 117           current stack trace (which you should report), but the
 118           system will stay locked up. This feature has negligible
 119           overhead.
 120
 121           (Note that "hard lockups" are separate type of bugs that
 122            can be detected via the NMI-watchdog, on platforms that
 123            support it.)
 124
 125 config SCHEDSTATS
 126         bool "Collect scheduler statistics"
 127         depends on DEBUG_KERNEL && PROC_FS
 128         help
 129           If you say Y here, additional code will be inserted into the
 130           scheduler and related routines to collect statistics about
 131           scheduler behavior and provide them in /proc/schedstat.  These
 132           stats may be useful for both tuning and debugging the scheduler
 133           If you aren't debugging the scheduler or trying to tune a specific
 134           application, you can say N to avoid the very slight overhead
 135           this adds.
 136
 137 config TIMER_STATS
 138         bool "Collect kernel timers statistics"
 139         depends on DEBUG_KERNEL && PROC_FS
 140         help
 141           If you say Y here, additional code will be inserted into the
 142           timer routines to collect statistics about kernel timers being
 143           reprogrammed. The statistics can be read from /proc/timer_stats.
 144           The statistics collection is started by writing 1 to /proc/timer_stats,
 145           writing 0 stops it. This feature is useful to collect information
 146           about timer usage patterns in kernel and userspace.
 147
 148 config DEBUG_SLAB
 149         bool "Debug slab memory allocations"
 150         depends on DEBUG_KERNEL && SLAB
 151         help
 152           Say Y here to have the kernel do limited verification on memory
 153           allocation as well as poisoning memory on free to catch use of freed
 154           memory. This can make kmalloc/kfree-intensive workloads much slower.
 155
 156 config DEBUG_SLAB_LEAK
 157         bool "Memory leak debugging"
 158         depends on DEBUG_SLAB
 159
 160 config DEBUG_PREEMPT
 161         bool "Debug preemptible kernel"
 162         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 163         default y
 164         help
 165           If you say Y here then the kernel will use a debug variant of the
 166           commonly used smp_processor_id() function and will print warnings
 167           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 168           will detect preemption count underflows.
 169
 170 config DEBUG_RT_MUTEXES
 171         bool "RT Mutex debugging, deadlock detection"
 172         depends on DEBUG_KERNEL && RT_MUTEXES
 173         help
 174          This allows rt mutex semantics violations and rt mutex related
 175          deadlocks (lockups) to be detected and reported automatically.
 176
 177 config DEBUG_PI_LIST
 178         bool
 179         default y
 180         depends on DEBUG_RT_MUTEXES
 181
 182 config RT_MUTEX_TESTER
 183         bool "Built-in scriptable tester for rt-mutexes"
 184         depends on DEBUG_KERNEL && RT_MUTEXES
 185         help
 186           This option enables a rt-mutex tester.
 187
 188 config DEBUG_SPINLOCK
 189         bool "Spinlock and rw-lock debugging: basic checks"
 190         depends on DEBUG_KERNEL
 191         help
 192           Say Y here and build SMP to catch missing spinlock initialization
 193           and certain other kinds of spinlock errors commonly made.  This is
 194           best used in conjunction with the NMI watchdog so that spinlock
 195           deadlocks are also debuggable.
 196
 197 config DEBUG_MUTEXES
 198         bool "Mutex debugging: basic checks"
 199         depends on DEBUG_KERNEL
 200         help
 201          This feature allows mutex semantics violations to be detected and
 202          reported.
 203
 204 config DEBUG_LOCK_ALLOC
 205         bool "Lock debugging: detect incorrect freeing of live locks"
 206         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 207         select DEBUG_SPINLOCK
 208         select DEBUG_MUTEXES
 209         select LOCKDEP
 210         help
 211          This feature will check whether any held lock (spinlock, rwlock,
 212          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 213          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 214          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 215          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 216          held during task exit.
 217
 218 config PROVE_LOCKING
 219         bool "Lock debugging: prove locking correctness"
 220         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 221         select LOCKDEP
 222         select DEBUG_SPINLOCK
 223         select DEBUG_MUTEXES
 224         select DEBUG_LOCK_ALLOC
 225         default n
 226         help
 227          This feature enables the kernel to prove that all locking
 228          that occurs in the kernel runtime is mathematically
 229          correct: that under no circumstance could an arbitrary (and
 230          not yet triggered) combination of observed locking
 231          sequences (on an arbitrary number of CPUs, running an
 232          arbitrary number of tasks and interrupt contexts) cause a
 233          deadlock.
 234
 235          In short, this feature enables the kernel to report locking
 236          related deadlocks before they actually occur.
 237
 238          The proof does not depend on how hard and complex a
 239          deadlock scenario would be to trigger: how many
 240          participant CPUs, tasks and irq-contexts would be needed
 241          for it to trigger. The proof also does not depend on
 242          timing: if a race and a resulting deadlock is possible
 243          theoretically (no matter how unlikely the race scenario
 244          is), it will be proven so and will immediately be
 245          reported by the kernel (once the event is observed that
 246          makes the deadlock theoretically possible).
 247
 248          If a deadlock is impossible (i.e. the locking rules, as
 249          observed by the kernel, are mathematically correct), the
 250          kernel reports nothing.
 251
 252          NOTE: this feature can also be enabled for rwlocks, mutexes
 253          and rwsems - in which case all dependencies between these
 254          different locking variants are observed and mapped too, and
 255          the proof of observed correctness is also maintained for an
 256          arbitrary combination of these separate locking variants.
 257
 258          For more details, see Documentation/lockdep-design.txt.
 259
 260 config LOCKDEP
 261         bool
 262         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 263         select STACKTRACE
 264         select FRAME_POINTER if !X86 && !MIPS
 265         select KALLSYMS
 266         select KALLSYMS_ALL
 267
 268 config DEBUG_LOCKDEP
 269         bool "Lock dependency engine debugging"
 270         depends on DEBUG_KERNEL && LOCKDEP
 271         help
 272           If you say Y here, the lock dependency engine will do
 273           additional runtime checks to debug itself, at the price
 274           of more runtime overhead.
 275
 276 config TRACE_IRQFLAGS
 277         depends on DEBUG_KERNEL
 278         bool
 279         default y
 280         depends on TRACE_IRQFLAGS_SUPPORT
 281         depends on PROVE_LOCKING
 282
 283 config DEBUG_SPINLOCK_SLEEP
 284         bool "Spinlock debugging: sleep-inside-spinlock checking"
 285         depends on DEBUG_KERNEL
 286         help
 287           If you say Y here, various routines which may sleep will become very
 288           noisy if they are called with a spinlock held.
 289
 290 config DEBUG_LOCKING_API_SELFTESTS
 291         bool "Locking API boot-time self-tests"
 292         depends on DEBUG_KERNEL
 293         help
 294           Say Y here if you want the kernel to run a short self-test during
 295           bootup. The self-test checks whether common types of locking bugs
 296           are detected by debugging mechanisms or not. (if you disable
 297           lock debugging then those bugs wont be detected of course.)
 298           The following locking APIs are covered: spinlocks, rwlocks,
 299           mutexes and rwsems.
 300
 301 config STACKTRACE
 302         bool
 303         depends on DEBUG_KERNEL
 304         depends on STACKTRACE_SUPPORT
 305
 306 config DEBUG_KOBJECT
 307         bool "kobject debugging"
 308         depends on DEBUG_KERNEL
 309         help
 310           If you say Y here, some extra kobject debugging messages will be sent
 311           to the syslog.
 312
 313 config DEBUG_HIGHMEM
 314         bool "Highmem debugging"
 315         depends on DEBUG_KERNEL && HIGHMEM
 316         help
 317           This options enables addition error checking for high memory systems.
 318           Disable for production systems.
 319
 320 config DEBUG_BUGVERBOSE
 321         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 322         depends on BUG
 323         depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG || BFIN
 324         default !EMBEDDED
 325         help
 326           Say Y here to make BUG() panics output the file name and line number
 327           of the BUG call as well as the EIP and oops trace.  This aids
 328           debugging but costs about 70-100K of memory.
 329
 330 config DEBUG_INFO
 331         bool "Compile the kernel with debug info"
 332         depends on DEBUG_KERNEL
 333         help
 334           If you say Y here the resulting kernel image will include
 335           debugging info resulting in a larger kernel image.
 336           This adds debug symbols to the kernel and modules (gcc -g), and
 337           is needed if you intend to use kernel crashdump or binary object
 338           tools like crash, kgdb, LKCD, gdb, etc on the kernel.
 339           Say Y here only if you plan to debug the kernel.
 340
 341           If unsure, say N.
 342
 343 config DEBUG_VM
 344         bool "Debug VM"
 345         depends on DEBUG_KERNEL
 346         help
 347           Enable this to turn on extended checks in the virtual-memory system
 348           that may impact performance.
 349
 350           If unsure, say N.
 351
 352 config DEBUG_LIST
 353         bool "Debug linked list manipulation"
 354         depends on DEBUG_KERNEL
 355         help
 356           Enable this to turn on extended checks in the linked-list
 357           walking routines.
 358
 359           If unsure, say N.
 360
 361 config FRAME_POINTER
 362         bool "Compile the kernel with frame pointers"
 363         depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH || BFIN)
 364         default y if DEBUG_INFO && UML
 365         help
 366           If you say Y here the resulting kernel image will be slightly larger
 367           and slower, but it might give very useful debugging information on
 368           some architectures or if you use external debuggers.
 369           If you don't debug the kernel, you can say N.
 370
 371 config FORCED_INLINING
 372         bool "Force gcc to inline functions marked 'inline'"
 373         depends on DEBUG_KERNEL
 374         default y
 375         help
 376           This option determines if the kernel forces gcc to inline the functions
 377           developers have marked 'inline'. Doing so takes away freedom from gcc to
 378           do what it thinks is best, which is desirable for the gcc 3.x series of
 379           compilers. The gcc 4.x series have a rewritten inlining algorithm and
 380           disabling this option will generate a smaller kernel there. Hopefully
 381           this algorithm is so good that allowing gcc4 to make the decision can
 382           become the default in the future, until then this option is there to
 383           test gcc for this.
 384
 385 config RCU_TORTURE_TEST
 386         tristate "torture tests for RCU"
 387         depends on DEBUG_KERNEL
 388         default n
 389         help
 390           This option provides a kernel module that runs torture tests
 391           on the RCU infrastructure.  The kernel module may be built
 392           after the fact on the running kernel to be tested, if desired.
 393
 394           Say Y here if you want RCU torture tests to start automatically
 395           at boot time (you probably don't).
 396           Say M if you want the RCU torture tests to build as a module.
 397           Say N if you are unsure.
 398
 399 config LKDTM
 400         tristate "Linux Kernel Dump Test Tool Module"
 401         depends on DEBUG_KERNEL
 402         depends on KPROBES
 403         default n
 404         help
 405         This module enables testing of the different dumping mechanisms by
 406         inducing system failures at predefined crash points.
 407         If you don't need it: say N
 408         Choose M here to compile this code as a module. The module will be
 409         called lkdtm.
 410
 411         Documentation on how to use the module can be found in
 412         drivers/misc/lkdtm.c
 413
 414 config FAULT_INJECTION
 415         bool "Fault-injection framework"
 416         depends on DEBUG_KERNEL
 417         help
 418           Provide fault-injection framework.
 419           For more details, see Documentation/fault-injection/.
 420
 421 config FAILSLAB
 422         bool "Fault-injection capability for kmalloc"
 423         depends on FAULT_INJECTION
 424         help
 425           Provide fault-injection capability for kmalloc.
 426
 427 config FAIL_PAGE_ALLOC
 428         bool "Fault-injection capabilitiy for alloc_pages()"
 429         depends on FAULT_INJECTION
 430         help
 431           Provide fault-injection capability for alloc_pages().
 432
 433 config FAIL_MAKE_REQUEST
 434         bool "Fault-injection capability for disk IO"
 435         depends on FAULT_INJECTION
 436         help
 437           Provide fault-injection capability for disk IO.
 438
 439 config FAULT_INJECTION_DEBUG_FS
 440         bool "Debugfs entries for fault-injection capabilities"
 441         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 442         help
 443           Enable configuration of fault-injection capabilities via debugfs.
 444
 445 config FAULT_INJECTION_STACKTRACE_FILTER
 446         bool "stacktrace filter for fault-injection capabilities"
 447         depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
 448         select STACKTRACE
 449         select FRAME_POINTER
 450         help
 451           Provide stacktrace filter for fault-injection capabilities