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 LOG_BUF_SHIFT
  81         int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
  82         range 12 21
  83         default 17 if S390 || LOCKDEP
  84         default 16 if X86_NUMAQ || IA64
  85         default 15 if SMP
  86         default 14
  87         help
  88           Select kernel log buffer size as a power of 2.
  89           Defaults and Examples:
  90                      17 => 128 KB for S/390
  91                      16 => 64 KB for x86 NUMAQ or IA-64
  92                      15 => 32 KB for SMP
  93                      14 => 16 KB for uniprocessor
  94                      13 =>  8 KB
  95                      12 =>  4 KB
  96
  97 config DETECT_SOFTLOCKUP
  98         bool "Detect Soft Lockups"
  99         depends on DEBUG_KERNEL && !S390
 100         default y
 101         help
 102           Say Y here to enable the kernel to detect "soft lockups",
 103           which are bugs that cause the kernel to loop in kernel
 104           mode for more than 10 seconds, without giving other tasks a
 105           chance to run.
 106
 107           When a soft-lockup is detected, the kernel will print the
 108           current stack trace (which you should report), but the
 109           system will stay locked up. This feature has negligible
 110           overhead.
 111
 112           (Note that "hard lockups" are separate type of bugs that
 113            can be detected via the NMI-watchdog, on platforms that
 114            support it.)
 115
 116 config SCHEDSTATS
 117         bool "Collect scheduler statistics"
 118         depends on DEBUG_KERNEL && PROC_FS
 119         help
 120           If you say Y here, additional code will be inserted into the
 121           scheduler and related routines to collect statistics about
 122           scheduler behavior and provide them in /proc/schedstat.  These
 123           stats may be useful for both tuning and debugging the scheduler
 124           If you aren't debugging the scheduler or trying to tune a specific
 125           application, you can say N to avoid the very slight overhead
 126           this adds.
 127
 128 config DEBUG_SLAB
 129         bool "Debug slab memory allocations"
 130         depends on DEBUG_KERNEL && SLAB
 131         help
 132           Say Y here to have the kernel do limited verification on memory
 133           allocation as well as poisoning memory on free to catch use of freed
 134           memory. This can make kmalloc/kfree-intensive workloads much slower.
 135
 136 config DEBUG_SLAB_LEAK
 137         bool "Memory leak debugging"
 138         depends on DEBUG_SLAB
 139
 140 config DEBUG_PREEMPT
 141         bool "Debug preemptible kernel"
 142         depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
 143         default y
 144         help
 145           If you say Y here then the kernel will use a debug variant of the
 146           commonly used smp_processor_id() function and will print warnings
 147           if kernel code uses it in a preemption-unsafe way. Also, the kernel
 148           will detect preemption count underflows.
 149
 150 config DEBUG_RT_MUTEXES
 151         bool "RT Mutex debugging, deadlock detection"
 152         depends on DEBUG_KERNEL && RT_MUTEXES
 153         help
 154          This allows rt mutex semantics violations and rt mutex related
 155          deadlocks (lockups) to be detected and reported automatically.
 156
 157 config DEBUG_PI_LIST
 158         bool
 159         default y
 160         depends on DEBUG_RT_MUTEXES
 161
 162 config RT_MUTEX_TESTER
 163         bool "Built-in scriptable tester for rt-mutexes"
 164         depends on DEBUG_KERNEL && RT_MUTEXES
 165         help
 166           This option enables a rt-mutex tester.
 167
 168 config DEBUG_SPINLOCK
 169         bool "Spinlock and rw-lock debugging: basic checks"
 170         depends on DEBUG_KERNEL
 171         help
 172           Say Y here and build SMP to catch missing spinlock initialization
 173           and certain other kinds of spinlock errors commonly made.  This is
 174           best used in conjunction with the NMI watchdog so that spinlock
 175           deadlocks are also debuggable.
 176
 177 config DEBUG_MUTEXES
 178         bool "Mutex debugging: basic checks"
 179         depends on DEBUG_KERNEL
 180         help
 181          This feature allows mutex semantics violations to be detected and
 182          reported.
 183
 184 config DEBUG_RWSEMS
 185         bool "RW-sem debugging: basic checks"
 186         depends on DEBUG_KERNEL
 187         help
 188          This feature allows read-write semaphore semantics violations to
 189          be detected and reported.
 190
 191 config DEBUG_LOCK_ALLOC
 192         bool "Lock debugging: detect incorrect freeing of live locks"
 193         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 194         select DEBUG_SPINLOCK
 195         select DEBUG_MUTEXES
 196         select DEBUG_RWSEMS
 197         select LOCKDEP
 198         help
 199          This feature will check whether any held lock (spinlock, rwlock,
 200          mutex or rwsem) is incorrectly freed by the kernel, via any of the
 201          memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
 202          vfree(), etc.), whether a live lock is incorrectly reinitialized via
 203          spin_lock_init()/mutex_init()/etc., or whether there is any lock
 204          held during task exit.
 205
 206 config PROVE_LOCKING
 207         bool "Lock debugging: prove locking correctness"
 208         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 209         select LOCKDEP
 210         select DEBUG_SPINLOCK
 211         select DEBUG_MUTEXES
 212         select DEBUG_RWSEMS
 213         select DEBUG_LOCK_ALLOC
 214         default n
 215         help
 216          This feature enables the kernel to prove that all locking
 217          that occurs in the kernel runtime is mathematically
 218          correct: that under no circumstance could an arbitrary (and
 219          not yet triggered) combination of observed locking
 220          sequences (on an arbitrary number of CPUs, running an
 221          arbitrary number of tasks and interrupt contexts) cause a
 222          deadlock.
 223
 224          In short, this feature enables the kernel to report locking
 225          related deadlocks before they actually occur.
 226
 227          The proof does not depend on how hard and complex a
 228          deadlock scenario would be to trigger: how many
 229          participant CPUs, tasks and irq-contexts would be needed
 230          for it to trigger. The proof also does not depend on
 231          timing: if a race and a resulting deadlock is possible
 232          theoretically (no matter how unlikely the race scenario
 233          is), it will be proven so and will immediately be
 234          reported by the kernel (once the event is observed that
 235          makes the deadlock theoretically possible).
 236
 237          If a deadlock is impossible (i.e. the locking rules, as
 238          observed by the kernel, are mathematically correct), the
 239          kernel reports nothing.
 240
 241          NOTE: this feature can also be enabled for rwlocks, mutexes
 242          and rwsems - in which case all dependencies between these
 243          different locking variants are observed and mapped too, and
 244          the proof of observed correctness is also maintained for an
 245          arbitrary combination of these separate locking variants.
 246
 247          For more details, see Documentation/lockdep-design.txt.
 248
 249 config LOCKDEP
 250         bool
 251         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
 252         select STACKTRACE
 253         select FRAME_POINTER if !X86
 254         select KALLSYMS
 255         select KALLSYMS_ALL
 256
 257 config DEBUG_LOCKDEP
 258         bool "Lock dependency engine debugging"
 259         depends on DEBUG_KERNEL && LOCKDEP
 260         help
 261           If you say Y here, the lock dependency engine will do
 262           additional runtime checks to debug itself, at the price
 263           of more runtime overhead.
 264
 265 config TRACE_IRQFLAGS
 266         depends on DEBUG_KERNEL
 267         bool
 268         default y
 269         depends on TRACE_IRQFLAGS_SUPPORT
 270         depends on PROVE_LOCKING
 271
 272 config DEBUG_SPINLOCK_SLEEP
 273         bool "Spinlock debugging: sleep-inside-spinlock checking"
 274         depends on DEBUG_KERNEL
 275         help
 276           If you say Y here, various routines which may sleep will become very
 277           noisy if they are called with a spinlock held.
 278
 279 config DEBUG_LOCKING_API_SELFTESTS
 280         bool "Locking API boot-time self-tests"
 281         depends on DEBUG_KERNEL
 282         help
 283           Say Y here if you want the kernel to run a short self-test during
 284           bootup. The self-test checks whether common types of locking bugs
 285           are detected by debugging mechanisms or not. (if you disable
 286           lock debugging then those bugs wont be detected of course.)
 287           The following locking APIs are covered: spinlocks, rwlocks,
 288           mutexes and rwsems.
 289
 290 config STACKTRACE
 291         bool
 292         depends on DEBUG_KERNEL
 293         depends on STACKTRACE_SUPPORT
 294
 295 config DEBUG_KOBJECT
 296         bool "kobject debugging"
 297         depends on DEBUG_KERNEL
 298         help
 299           If you say Y here, some extra kobject debugging messages will be sent
 300           to the syslog.
 301
 302 config DEBUG_HIGHMEM
 303         bool "Highmem debugging"
 304         depends on DEBUG_KERNEL && HIGHMEM
 305         help
 306           This options enables addition error checking for high memory systems.
 307           Disable for production systems.
 308
 309 config DEBUG_BUGVERBOSE
 310         bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
 311         depends on BUG
 312         depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG
 313         default !EMBEDDED
 314         help
 315           Say Y here to make BUG() panics output the file name and line number
 316           of the BUG call as well as the EIP and oops trace.  This aids
 317           debugging but costs about 70-100K of memory.
 318
 319 config DEBUG_INFO
 320         bool "Compile the kernel with debug info"
 321         depends on DEBUG_KERNEL
 322         help
 323           If you say Y here the resulting kernel image will include
 324           debugging info resulting in a larger kernel image.
 325           Say Y here only if you plan to debug the kernel.
 326
 327           If unsure, say N.
 328
 329 config DEBUG_VM
 330         bool "Debug VM"
 331         depends on DEBUG_KERNEL
 332         help
 333           Enable this to turn on extended checks in the virtual-memory system
 334           that may impact performance.
 335
 336           If unsure, say N.
 337
 338 config DEBUG_LIST
 339         bool "Debug linked list manipulation"
 340         depends on DEBUG_KERNEL
 341         help
 342           Enable this to turn on extended checks in the linked-list
 343           walking routines.
 344
 345           If unsure, say N.
 346
 347 config FRAME_POINTER
 348         bool "Compile the kernel with frame pointers"
 349         depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH)
 350         default y if DEBUG_INFO && UML
 351         help
 352           If you say Y here the resulting kernel image will be slightly larger
 353           and slower, but it might give very useful debugging information on
 354           some architectures or if you use external debuggers.
 355           If you don't debug the kernel, you can say N.
 356
 357 config UNWIND_INFO
 358         bool "Compile the kernel with frame unwind information"
 359         depends on !IA64 && !PARISC && !ARM
 360         depends on !MODULES || !(MIPS || PPC || SUPERH || V850)
 361         help
 362           If you say Y here the resulting kernel image will be slightly larger
 363           but not slower, and it will give very useful debugging information.
 364           If you don't debug the kernel, you can say N, but we may not be able
 365           to solve problems without frame unwind information or frame pointers.
 366
 367 config STACK_UNWIND
 368         bool "Stack unwind support"
 369         depends on UNWIND_INFO
 370         depends on X86
 371         help
 372           This enables more precise stack traces, omitting all unrelated
 373           occurrences of pointers into kernel code from the dump.
 374
 375 config FORCED_INLINING
 376         bool "Force gcc to inline functions marked 'inline'"
 377         depends on DEBUG_KERNEL
 378         default y
 379         help
 380           This option determines if the kernel forces gcc to inline the functions
 381           developers have marked 'inline'. Doing so takes away freedom from gcc to
 382           do what it thinks is best, which is desirable for the gcc 3.x series of
 383           compilers. The gcc 4.x series have a rewritten inlining algorithm and
 384           disabling this option will generate a smaller kernel there. Hopefully
 385           this algorithm is so good that allowing gcc4 to make the decision can
 386           become the default in the future, until then this option is there to
 387           test gcc for this.
 388
 389 config RCU_TORTURE_TEST
 390         tristate "torture tests for RCU"
 391         depends on DEBUG_KERNEL
 392         default n
 393         help
 394           This option provides a kernel module that runs torture tests
 395           on the RCU infrastructure.  The kernel module may be built
 396           after the fact on the running kernel to be tested, if desired.
 397
 398           Say Y here if you want RCU torture tests to start automatically
 399           at boot time (you probably don't).
 400           Say M if you want the RCU torture tests to build as a module.
 401           Say N if you are unsure.
 402
 403 config LKDTM
 404         tristate "Linux Kernel Dump Test Tool Module"
 405         depends on DEBUG_KERNEL
 406         depends on KPROBES
 407         default n
 408         help
 409         This module enables testing of the different dumping mechanisms by
 410         inducing system failures at predefined crash points.
 411         If you don't need it: say N
 412         Choose M here to compile this code as a module. The module will be
 413         called lkdtm.
 414
 415         Documentation on how to use the module can be found in
 416         drivers/misc/lkdtm.c
 417
 418 config FAULT_INJECTION
 419         bool "Fault-injection framework"
 420         depends on DEBUG_KERNEL
 421         depends on STACKTRACE
 422         select FRAME_POINTER
 423         help
 424           Provide fault-injection framework.
 425           For more details, see Documentation/fault-injection/.
 426
 427 config FAILSLAB
 428         bool "Fault-injection capability for kmalloc"
 429         depends on FAULT_INJECTION
 430         help
 431           Provide fault-injection capability for kmalloc.
 432
 433 config FAIL_PAGE_ALLOC
 434         bool "Fault-injection capabilitiy for alloc_pages()"
 435         depends on FAULT_INJECTION
 436         help
 437           Provide fault-injection capability for alloc_pages().
 438
 439 config FAIL_MAKE_REQUEST
 440         bool "Fault-injection capabilitiy for disk IO"
 441         depends on FAULT_INJECTION
 442         help
 443           Provide fault-injection capability for disk IO.
 444
 445 config FAULT_INJECTION_DEBUG_FS
 446         bool "Debugfs entries for fault-injection capabilities"
 447         depends on FAULT_INJECTION && SYSFS && DEBUG_FS
 448         help
 449           Enable configuration of fault-injection capabilities via debugfs.