Kconfig.debug 43 KB

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  1. config PRINTK_TIME
  2. bool "Show timing information on printks"
  3. depends on PRINTK
  4. help
  5. Selecting this option causes timing information to be
  6. included in printk output. This allows you to measure
  7. the interval between kernel operations, including bootup
  8. operations. This is useful for identifying long delays
  9. in kernel startup.
  10. config DEFAULT_MESSAGE_LOGLEVEL
  11. int "Default message log level (1-7)"
  12. range 1 7
  13. default "4"
  14. help
  15. Default log level for printk statements with no specified priority.
  16. This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
  17. that are auditing their logs closely may want to set it to a lower
  18. priority.
  19. config ENABLE_WARN_DEPRECATED
  20. bool "Enable __deprecated logic"
  21. default y
  22. help
  23. Enable the __deprecated logic in the kernel build.
  24. Disable this to suppress the "warning: 'foo' is deprecated
  25. (declared at kernel/power/somefile.c:1234)" messages.
  26. config ENABLE_MUST_CHECK
  27. bool "Enable __must_check logic"
  28. default y
  29. help
  30. Enable the __must_check logic in the kernel build. Disable this to
  31. suppress the "warning: ignoring return value of 'foo', declared with
  32. attribute warn_unused_result" messages.
  33. config FRAME_WARN
  34. int "Warn for stack frames larger than (needs gcc 4.4)"
  35. range 0 8192
  36. default 1024 if !64BIT
  37. default 2048 if 64BIT
  38. help
  39. Tell gcc to warn at build time for stack frames larger than this.
  40. Setting this too low will cause a lot of warnings.
  41. Setting it to 0 disables the warning.
  42. Requires gcc 4.4
  43. config MAGIC_SYSRQ
  44. bool "Magic SysRq key"
  45. depends on !UML
  46. help
  47. If you say Y here, you will have some control over the system even
  48. if the system crashes for example during kernel debugging (e.g., you
  49. will be able to flush the buffer cache to disk, reboot the system
  50. immediately or dump some status information). This is accomplished
  51. by pressing various keys while holding SysRq (Alt+PrintScreen). It
  52. also works on a serial console (on PC hardware at least), if you
  53. send a BREAK and then within 5 seconds a command keypress. The
  54. keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  55. unless you really know what this hack does.
  56. config STRIP_ASM_SYMS
  57. bool "Strip assembler-generated symbols during link"
  58. default n
  59. help
  60. Strip internal assembler-generated symbols during a link (symbols
  61. that look like '.Lxxx') so they don't pollute the output of
  62. get_wchan() and suchlike.
  63. config UNUSED_SYMBOLS
  64. bool "Enable unused/obsolete exported symbols"
  65. default y if X86
  66. help
  67. Unused but exported symbols make the kernel needlessly bigger. For
  68. that reason most of these unused exports will soon be removed. This
  69. option is provided temporarily to provide a transition period in case
  70. some external kernel module needs one of these symbols anyway. If you
  71. encounter such a case in your module, consider if you are actually
  72. using the right API. (rationale: since nobody in the kernel is using
  73. this in a module, there is a pretty good chance it's actually the
  74. wrong interface to use). If you really need the symbol, please send a
  75. mail to the linux kernel mailing list mentioning the symbol and why
  76. you really need it, and what the merge plan to the mainline kernel for
  77. your module is.
  78. config DEBUG_FS
  79. bool "Debug Filesystem"
  80. help
  81. debugfs is a virtual file system that kernel developers use to put
  82. debugging files into. Enable this option to be able to read and
  83. write to these files.
  84. For detailed documentation on the debugfs API, see
  85. Documentation/DocBook/filesystems.
  86. If unsure, say N.
  87. config HEADERS_CHECK
  88. bool "Run 'make headers_check' when building vmlinux"
  89. depends on !UML
  90. help
  91. This option will extract the user-visible kernel headers whenever
  92. building the kernel, and will run basic sanity checks on them to
  93. ensure that exported files do not attempt to include files which
  94. were not exported, etc.
  95. If you're making modifications to header files which are
  96. relevant for userspace, say 'Y', and check the headers
  97. exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  98. your build tree), to make sure they're suitable.
  99. config DEBUG_SECTION_MISMATCH
  100. bool "Enable full Section mismatch analysis"
  101. help
  102. The section mismatch analysis checks if there are illegal
  103. references from one section to another section.
  104. Linux will during link or during runtime drop some sections
  105. and any use of code/data previously in these sections will
  106. most likely result in an oops.
  107. In the code functions and variables are annotated with
  108. __init, __devinit etc. (see full list in include/linux/init.h)
  109. which results in the code/data being placed in specific sections.
  110. The section mismatch analysis is always done after a full
  111. kernel build but enabling this option will in addition
  112. do the following:
  113. - Add the option -fno-inline-functions-called-once to gcc
  114. When inlining a function annotated __init in a non-init
  115. function we would lose the section information and thus
  116. the analysis would not catch the illegal reference.
  117. This option tells gcc to inline less but will also
  118. result in a larger kernel.
  119. - Run the section mismatch analysis for each module/built-in.o
  120. When we run the section mismatch analysis on vmlinux.o we
  121. lose valueble information about where the mismatch was
  122. introduced.
  123. Running the analysis for each module/built-in.o file
  124. will tell where the mismatch happens much closer to the
  125. source. The drawback is that we will report the same
  126. mismatch at least twice.
  127. - Enable verbose reporting from modpost to help solving
  128. the section mismatches reported.
  129. config DEBUG_KERNEL
  130. bool "Kernel debugging"
  131. help
  132. Say Y here if you are developing drivers or trying to debug and
  133. identify kernel problems.
  134. config DEBUG_SHIRQ
  135. bool "Debug shared IRQ handlers"
  136. depends on DEBUG_KERNEL && GENERIC_HARDIRQS
  137. help
  138. Enable this to generate a spurious interrupt as soon as a shared
  139. interrupt handler is registered, and just before one is deregistered.
  140. Drivers ought to be able to handle interrupts coming in at those
  141. points; some don't and need to be caught.
  142. config LOCKUP_DETECTOR
  143. bool "Detect Hard and Soft Lockups"
  144. depends on DEBUG_KERNEL && !S390
  145. help
  146. Say Y here to enable the kernel to act as a watchdog to detect
  147. hard and soft lockups.
  148. Softlockups are bugs that cause the kernel to loop in kernel
  149. mode for more than 60 seconds, without giving other tasks a
  150. chance to run. The current stack trace is displayed upon
  151. detection and the system will stay locked up.
  152. Hardlockups are bugs that cause the CPU to loop in kernel mode
  153. for more than 60 seconds, without letting other interrupts have a
  154. chance to run. The current stack trace is displayed upon detection
  155. and the system will stay locked up.
  156. The overhead should be minimal. A periodic hrtimer runs to
  157. generate interrupts and kick the watchdog task every 10-12 seconds.
  158. An NMI is generated every 60 seconds or so to check for hardlockups.
  159. config HARDLOCKUP_DETECTOR
  160. def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
  161. !ARCH_HAS_NMI_WATCHDOG
  162. config BOOTPARAM_HARDLOCKUP_PANIC
  163. bool "Panic (Reboot) On Hard Lockups"
  164. depends on LOCKUP_DETECTOR
  165. help
  166. Say Y here to enable the kernel to panic on "hard lockups",
  167. which are bugs that cause the kernel to loop in kernel
  168. mode with interrupts disabled for more than 60 seconds.
  169. Say N if unsure.
  170. config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
  171. int
  172. depends on LOCKUP_DETECTOR
  173. range 0 1
  174. default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
  175. default 1 if BOOTPARAM_HARDLOCKUP_PANIC
  176. config BOOTPARAM_SOFTLOCKUP_PANIC
  177. bool "Panic (Reboot) On Soft Lockups"
  178. depends on LOCKUP_DETECTOR
  179. help
  180. Say Y here to enable the kernel to panic on "soft lockups",
  181. which are bugs that cause the kernel to loop in kernel
  182. mode for more than 60 seconds, without giving other tasks a
  183. chance to run.
  184. The panic can be used in combination with panic_timeout,
  185. to cause the system to reboot automatically after a
  186. lockup has been detected. This feature is useful for
  187. high-availability systems that have uptime guarantees and
  188. where a lockup must be resolved ASAP.
  189. Say N if unsure.
  190. config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
  191. int
  192. depends on LOCKUP_DETECTOR
  193. range 0 1
  194. default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
  195. default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
  196. config DETECT_HUNG_TASK
  197. bool "Detect Hung Tasks"
  198. depends on DEBUG_KERNEL
  199. default DETECT_SOFTLOCKUP
  200. help
  201. Say Y here to enable the kernel to detect "hung tasks",
  202. which are bugs that cause the task to be stuck in
  203. uninterruptible "D" state indefinitiley.
  204. When a hung task is detected, the kernel will print the
  205. current stack trace (which you should report), but the
  206. task will stay in uninterruptible state. If lockdep is
  207. enabled then all held locks will also be reported. This
  208. feature has negligible overhead.
  209. config BOOTPARAM_HUNG_TASK_PANIC
  210. bool "Panic (Reboot) On Hung Tasks"
  211. depends on DETECT_HUNG_TASK
  212. help
  213. Say Y here to enable the kernel to panic on "hung tasks",
  214. which are bugs that cause the kernel to leave a task stuck
  215. in uninterruptible "D" state.
  216. The panic can be used in combination with panic_timeout,
  217. to cause the system to reboot automatically after a
  218. hung task has been detected. This feature is useful for
  219. high-availability systems that have uptime guarantees and
  220. where a hung tasks must be resolved ASAP.
  221. Say N if unsure.
  222. config BOOTPARAM_HUNG_TASK_PANIC_VALUE
  223. int
  224. depends on DETECT_HUNG_TASK
  225. range 0 1
  226. default 0 if !BOOTPARAM_HUNG_TASK_PANIC
  227. default 1 if BOOTPARAM_HUNG_TASK_PANIC
  228. config SCHED_DEBUG
  229. bool "Collect scheduler debugging info"
  230. depends on DEBUG_KERNEL && PROC_FS
  231. default y
  232. help
  233. If you say Y here, the /proc/sched_debug file will be provided
  234. that can help debug the scheduler. The runtime overhead of this
  235. option is minimal.
  236. config SCHEDSTATS
  237. bool "Collect scheduler statistics"
  238. depends on DEBUG_KERNEL && PROC_FS
  239. help
  240. If you say Y here, additional code will be inserted into the
  241. scheduler and related routines to collect statistics about
  242. scheduler behavior and provide them in /proc/schedstat. These
  243. stats may be useful for both tuning and debugging the scheduler
  244. If you aren't debugging the scheduler or trying to tune a specific
  245. application, you can say N to avoid the very slight overhead
  246. this adds.
  247. config TIMER_STATS
  248. bool "Collect kernel timers statistics"
  249. depends on DEBUG_KERNEL && PROC_FS
  250. help
  251. If you say Y here, additional code will be inserted into the
  252. timer routines to collect statistics about kernel timers being
  253. reprogrammed. The statistics can be read from /proc/timer_stats.
  254. The statistics collection is started by writing 1 to /proc/timer_stats,
  255. writing 0 stops it. This feature is useful to collect information
  256. about timer usage patterns in kernel and userspace. This feature
  257. is lightweight if enabled in the kernel config but not activated
  258. (it defaults to deactivated on bootup and will only be activated
  259. if some application like powertop activates it explicitly).
  260. config DEBUG_OBJECTS
  261. bool "Debug object operations"
  262. depends on DEBUG_KERNEL
  263. help
  264. If you say Y here, additional code will be inserted into the
  265. kernel to track the life time of various objects and validate
  266. the operations on those objects.
  267. config DEBUG_OBJECTS_SELFTEST
  268. bool "Debug objects selftest"
  269. depends on DEBUG_OBJECTS
  270. help
  271. This enables the selftest of the object debug code.
  272. config DEBUG_OBJECTS_FREE
  273. bool "Debug objects in freed memory"
  274. depends on DEBUG_OBJECTS
  275. help
  276. This enables checks whether a k/v free operation frees an area
  277. which contains an object which has not been deactivated
  278. properly. This can make kmalloc/kfree-intensive workloads
  279. much slower.
  280. config DEBUG_OBJECTS_TIMERS
  281. bool "Debug timer objects"
  282. depends on DEBUG_OBJECTS
  283. help
  284. If you say Y here, additional code will be inserted into the
  285. timer routines to track the life time of timer objects and
  286. validate the timer operations.
  287. config DEBUG_OBJECTS_WORK
  288. bool "Debug work objects"
  289. depends on DEBUG_OBJECTS
  290. help
  291. If you say Y here, additional code will be inserted into the
  292. work queue routines to track the life time of work objects and
  293. validate the work operations.
  294. config DEBUG_OBJECTS_RCU_HEAD
  295. bool "Debug RCU callbacks objects"
  296. depends on DEBUG_OBJECTS && PREEMPT
  297. help
  298. Enable this to turn on debugging of RCU list heads (call_rcu() usage).
  299. config DEBUG_OBJECTS_PERCPU_COUNTER
  300. bool "Debug percpu counter objects"
  301. depends on DEBUG_OBJECTS
  302. help
  303. If you say Y here, additional code will be inserted into the
  304. percpu counter routines to track the life time of percpu counter
  305. objects and validate the percpu counter operations.
  306. config DEBUG_OBJECTS_ENABLE_DEFAULT
  307. int "debug_objects bootup default value (0-1)"
  308. range 0 1
  309. default "1"
  310. depends on DEBUG_OBJECTS
  311. help
  312. Debug objects boot parameter default value
  313. config DEBUG_SLAB
  314. bool "Debug slab memory allocations"
  315. depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
  316. help
  317. Say Y here to have the kernel do limited verification on memory
  318. allocation as well as poisoning memory on free to catch use of freed
  319. memory. This can make kmalloc/kfree-intensive workloads much slower.
  320. config DEBUG_SLAB_LEAK
  321. bool "Memory leak debugging"
  322. depends on DEBUG_SLAB
  323. config SLUB_DEBUG_ON
  324. bool "SLUB debugging on by default"
  325. depends on SLUB && SLUB_DEBUG && !KMEMCHECK
  326. default n
  327. help
  328. Boot with debugging on by default. SLUB boots by default with
  329. the runtime debug capabilities switched off. Enabling this is
  330. equivalent to specifying the "slub_debug" parameter on boot.
  331. There is no support for more fine grained debug control like
  332. possible with slub_debug=xxx. SLUB debugging may be switched
  333. off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
  334. "slub_debug=-".
  335. config SLUB_STATS
  336. default n
  337. bool "Enable SLUB performance statistics"
  338. depends on SLUB && SYSFS
  339. help
  340. SLUB statistics are useful to debug SLUBs allocation behavior in
  341. order find ways to optimize the allocator. This should never be
  342. enabled for production use since keeping statistics slows down
  343. the allocator by a few percentage points. The slabinfo command
  344. supports the determination of the most active slabs to figure
  345. out which slabs are relevant to a particular load.
  346. Try running: slabinfo -DA
  347. config DEBUG_KMEMLEAK
  348. bool "Kernel memory leak detector"
  349. depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
  350. (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
  351. select DEBUG_FS if SYSFS
  352. select STACKTRACE if STACKTRACE_SUPPORT
  353. select KALLSYMS
  354. select CRC32
  355. help
  356. Say Y here if you want to enable the memory leak
  357. detector. The memory allocation/freeing is traced in a way
  358. similar to the Boehm's conservative garbage collector, the
  359. difference being that the orphan objects are not freed but
  360. only shown in /sys/kernel/debug/kmemleak. Enabling this
  361. feature will introduce an overhead to memory
  362. allocations. See Documentation/kmemleak.txt for more
  363. details.
  364. Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
  365. of finding leaks due to the slab objects poisoning.
  366. In order to access the kmemleak file, debugfs needs to be
  367. mounted (usually at /sys/kernel/debug).
  368. config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
  369. int "Maximum kmemleak early log entries"
  370. depends on DEBUG_KMEMLEAK
  371. range 200 40000
  372. default 400
  373. help
  374. Kmemleak must track all the memory allocations to avoid
  375. reporting false positives. Since memory may be allocated or
  376. freed before kmemleak is initialised, an early log buffer is
  377. used to store these actions. If kmemleak reports "early log
  378. buffer exceeded", please increase this value.
  379. config DEBUG_KMEMLEAK_TEST
  380. tristate "Simple test for the kernel memory leak detector"
  381. depends on DEBUG_KMEMLEAK && m
  382. help
  383. This option enables a module that explicitly leaks memory.
  384. If unsure, say N.
  385. config DEBUG_KMEMLEAK_DEFAULT_OFF
  386. bool "Default kmemleak to off"
  387. depends on DEBUG_KMEMLEAK
  388. help
  389. Say Y here to disable kmemleak by default. It can then be enabled
  390. on the command line via kmemleak=on.
  391. config DEBUG_PREEMPT
  392. bool "Debug preemptible kernel"
  393. depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
  394. default y
  395. help
  396. If you say Y here then the kernel will use a debug variant of the
  397. commonly used smp_processor_id() function and will print warnings
  398. if kernel code uses it in a preemption-unsafe way. Also, the kernel
  399. will detect preemption count underflows.
  400. config DEBUG_RT_MUTEXES
  401. bool "RT Mutex debugging, deadlock detection"
  402. depends on DEBUG_KERNEL && RT_MUTEXES
  403. help
  404. This allows rt mutex semantics violations and rt mutex related
  405. deadlocks (lockups) to be detected and reported automatically.
  406. config DEBUG_PI_LIST
  407. bool
  408. default y
  409. depends on DEBUG_RT_MUTEXES
  410. config RT_MUTEX_TESTER
  411. bool "Built-in scriptable tester for rt-mutexes"
  412. depends on DEBUG_KERNEL && RT_MUTEXES
  413. help
  414. This option enables a rt-mutex tester.
  415. config DEBUG_SPINLOCK
  416. bool "Spinlock and rw-lock debugging: basic checks"
  417. depends on DEBUG_KERNEL
  418. help
  419. Say Y here and build SMP to catch missing spinlock initialization
  420. and certain other kinds of spinlock errors commonly made. This is
  421. best used in conjunction with the NMI watchdog so that spinlock
  422. deadlocks are also debuggable.
  423. config DEBUG_MUTEXES
  424. bool "Mutex debugging: basic checks"
  425. depends on DEBUG_KERNEL
  426. help
  427. This feature allows mutex semantics violations to be detected and
  428. reported.
  429. config DEBUG_LOCK_ALLOC
  430. bool "Lock debugging: detect incorrect freeing of live locks"
  431. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  432. select DEBUG_SPINLOCK
  433. select DEBUG_MUTEXES
  434. select LOCKDEP
  435. help
  436. This feature will check whether any held lock (spinlock, rwlock,
  437. mutex or rwsem) is incorrectly freed by the kernel, via any of the
  438. memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
  439. vfree(), etc.), whether a live lock is incorrectly reinitialized via
  440. spin_lock_init()/mutex_init()/etc., or whether there is any lock
  441. held during task exit.
  442. config PROVE_LOCKING
  443. bool "Lock debugging: prove locking correctness"
  444. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  445. select LOCKDEP
  446. select DEBUG_SPINLOCK
  447. select DEBUG_MUTEXES
  448. select DEBUG_LOCK_ALLOC
  449. select TRACE_IRQFLAGS
  450. default n
  451. help
  452. This feature enables the kernel to prove that all locking
  453. that occurs in the kernel runtime is mathematically
  454. correct: that under no circumstance could an arbitrary (and
  455. not yet triggered) combination of observed locking
  456. sequences (on an arbitrary number of CPUs, running an
  457. arbitrary number of tasks and interrupt contexts) cause a
  458. deadlock.
  459. In short, this feature enables the kernel to report locking
  460. related deadlocks before they actually occur.
  461. The proof does not depend on how hard and complex a
  462. deadlock scenario would be to trigger: how many
  463. participant CPUs, tasks and irq-contexts would be needed
  464. for it to trigger. The proof also does not depend on
  465. timing: if a race and a resulting deadlock is possible
  466. theoretically (no matter how unlikely the race scenario
  467. is), it will be proven so and will immediately be
  468. reported by the kernel (once the event is observed that
  469. makes the deadlock theoretically possible).
  470. If a deadlock is impossible (i.e. the locking rules, as
  471. observed by the kernel, are mathematically correct), the
  472. kernel reports nothing.
  473. NOTE: this feature can also be enabled for rwlocks, mutexes
  474. and rwsems - in which case all dependencies between these
  475. different locking variants are observed and mapped too, and
  476. the proof of observed correctness is also maintained for an
  477. arbitrary combination of these separate locking variants.
  478. For more details, see Documentation/lockdep-design.txt.
  479. config PROVE_RCU
  480. bool "RCU debugging: prove RCU correctness"
  481. depends on PROVE_LOCKING
  482. default n
  483. help
  484. This feature enables lockdep extensions that check for correct
  485. use of RCU APIs. This is currently under development. Say Y
  486. if you want to debug RCU usage or help work on the PROVE_RCU
  487. feature.
  488. Say N if you are unsure.
  489. config PROVE_RCU_REPEATEDLY
  490. bool "RCU debugging: don't disable PROVE_RCU on first splat"
  491. depends on PROVE_RCU
  492. default n
  493. help
  494. By itself, PROVE_RCU will disable checking upon issuing the
  495. first warning (or "splat"). This feature prevents such
  496. disabling, allowing multiple RCU-lockdep warnings to be printed
  497. on a single reboot.
  498. Say Y to allow multiple RCU-lockdep warnings per boot.
  499. Say N if you are unsure.
  500. config SPARSE_RCU_POINTER
  501. bool "RCU debugging: sparse-based checks for pointer usage"
  502. default n
  503. help
  504. This feature enables the __rcu sparse annotation for
  505. RCU-protected pointers. This annotation will cause sparse
  506. to flag any non-RCU used of annotated pointers. This can be
  507. helpful when debugging RCU usage. Please note that this feature
  508. is not intended to enforce code cleanliness; it is instead merely
  509. a debugging aid.
  510. Say Y to make sparse flag questionable use of RCU-protected pointers
  511. Say N if you are unsure.
  512. config LOCKDEP
  513. bool
  514. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  515. select STACKTRACE
  516. select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
  517. select KALLSYMS
  518. select KALLSYMS_ALL
  519. config LOCK_STAT
  520. bool "Lock usage statistics"
  521. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  522. select LOCKDEP
  523. select DEBUG_SPINLOCK
  524. select DEBUG_MUTEXES
  525. select DEBUG_LOCK_ALLOC
  526. default n
  527. help
  528. This feature enables tracking lock contention points
  529. For more details, see Documentation/lockstat.txt
  530. This also enables lock events required by "perf lock",
  531. subcommand of perf.
  532. If you want to use "perf lock", you also need to turn on
  533. CONFIG_EVENT_TRACING.
  534. CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
  535. (CONFIG_LOCKDEP defines "acquire" and "release" events.)
  536. config DEBUG_LOCKDEP
  537. bool "Lock dependency engine debugging"
  538. depends on DEBUG_KERNEL && LOCKDEP
  539. help
  540. If you say Y here, the lock dependency engine will do
  541. additional runtime checks to debug itself, at the price
  542. of more runtime overhead.
  543. config TRACE_IRQFLAGS
  544. bool
  545. help
  546. Enables hooks to interrupt enabling and disabling for
  547. either tracing or lock debugging.
  548. config DEBUG_SPINLOCK_SLEEP
  549. bool "Spinlock debugging: sleep-inside-spinlock checking"
  550. depends on DEBUG_KERNEL
  551. help
  552. If you say Y here, various routines which may sleep will become very
  553. noisy if they are called with a spinlock held.
  554. config DEBUG_LOCKING_API_SELFTESTS
  555. bool "Locking API boot-time self-tests"
  556. depends on DEBUG_KERNEL
  557. help
  558. Say Y here if you want the kernel to run a short self-test during
  559. bootup. The self-test checks whether common types of locking bugs
  560. are detected by debugging mechanisms or not. (if you disable
  561. lock debugging then those bugs wont be detected of course.)
  562. The following locking APIs are covered: spinlocks, rwlocks,
  563. mutexes and rwsems.
  564. config STACKTRACE
  565. bool
  566. depends on STACKTRACE_SUPPORT
  567. config DEBUG_KOBJECT
  568. bool "kobject debugging"
  569. depends on DEBUG_KERNEL
  570. help
  571. If you say Y here, some extra kobject debugging messages will be sent
  572. to the syslog.
  573. config DEBUG_HIGHMEM
  574. bool "Highmem debugging"
  575. depends on DEBUG_KERNEL && HIGHMEM
  576. help
  577. This options enables addition error checking for high memory systems.
  578. Disable for production systems.
  579. config DEBUG_BUGVERBOSE
  580. bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
  581. depends on BUG
  582. depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
  583. FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
  584. default y
  585. help
  586. Say Y here to make BUG() panics output the file name and line number
  587. of the BUG call as well as the EIP and oops trace. This aids
  588. debugging but costs about 70-100K of memory.
  589. config DEBUG_INFO
  590. bool "Compile the kernel with debug info"
  591. depends on DEBUG_KERNEL
  592. help
  593. If you say Y here the resulting kernel image will include
  594. debugging info resulting in a larger kernel image.
  595. This adds debug symbols to the kernel and modules (gcc -g), and
  596. is needed if you intend to use kernel crashdump or binary object
  597. tools like crash, kgdb, LKCD, gdb, etc on the kernel.
  598. Say Y here only if you plan to debug the kernel.
  599. If unsure, say N.
  600. config DEBUG_INFO_REDUCED
  601. bool "Reduce debugging information"
  602. depends on DEBUG_INFO
  603. help
  604. If you say Y here gcc is instructed to generate less debugging
  605. information for structure types. This means that tools that
  606. need full debugging information (like kgdb or systemtap) won't
  607. be happy. But if you merely need debugging information to
  608. resolve line numbers there is no loss. Advantage is that
  609. build directory object sizes shrink dramatically over a full
  610. DEBUG_INFO build and compile times are reduced too.
  611. Only works with newer gcc versions.
  612. config DEBUG_VM
  613. bool "Debug VM"
  614. depends on DEBUG_KERNEL
  615. help
  616. Enable this to turn on extended checks in the virtual-memory system
  617. that may impact performance.
  618. If unsure, say N.
  619. config DEBUG_VIRTUAL
  620. bool "Debug VM translations"
  621. depends on DEBUG_KERNEL && X86
  622. help
  623. Enable some costly sanity checks in virtual to page code. This can
  624. catch mistakes with virt_to_page() and friends.
  625. If unsure, say N.
  626. config DEBUG_NOMMU_REGIONS
  627. bool "Debug the global anon/private NOMMU mapping region tree"
  628. depends on DEBUG_KERNEL && !MMU
  629. help
  630. This option causes the global tree of anonymous and private mapping
  631. regions to be regularly checked for invalid topology.
  632. config DEBUG_WRITECOUNT
  633. bool "Debug filesystem writers count"
  634. depends on DEBUG_KERNEL
  635. help
  636. Enable this to catch wrong use of the writers count in struct
  637. vfsmount. This will increase the size of each file struct by
  638. 32 bits.
  639. If unsure, say N.
  640. config DEBUG_MEMORY_INIT
  641. bool "Debug memory initialisation" if EXPERT
  642. default !EXPERT
  643. help
  644. Enable this for additional checks during memory initialisation.
  645. The sanity checks verify aspects of the VM such as the memory model
  646. and other information provided by the architecture. Verbose
  647. information will be printed at KERN_DEBUG loglevel depending
  648. on the mminit_loglevel= command-line option.
  649. If unsure, say Y
  650. config DEBUG_LIST
  651. bool "Debug linked list manipulation"
  652. depends on DEBUG_KERNEL
  653. help
  654. Enable this to turn on extended checks in the linked-list
  655. walking routines.
  656. If unsure, say N.
  657. config TEST_LIST_SORT
  658. bool "Linked list sorting test"
  659. depends on DEBUG_KERNEL
  660. help
  661. Enable this to turn on 'list_sort()' function test. This test is
  662. executed only once during system boot, so affects only boot time.
  663. If unsure, say N.
  664. config DEBUG_SG
  665. bool "Debug SG table operations"
  666. depends on DEBUG_KERNEL
  667. help
  668. Enable this to turn on checks on scatter-gather tables. This can
  669. help find problems with drivers that do not properly initialize
  670. their sg tables.
  671. If unsure, say N.
  672. config DEBUG_NOTIFIERS
  673. bool "Debug notifier call chains"
  674. depends on DEBUG_KERNEL
  675. help
  676. Enable this to turn on sanity checking for notifier call chains.
  677. This is most useful for kernel developers to make sure that
  678. modules properly unregister themselves from notifier chains.
  679. This is a relatively cheap check but if you care about maximum
  680. performance, say N.
  681. config DEBUG_CREDENTIALS
  682. bool "Debug credential management"
  683. depends on DEBUG_KERNEL
  684. help
  685. Enable this to turn on some debug checking for credential
  686. management. The additional code keeps track of the number of
  687. pointers from task_structs to any given cred struct, and checks to
  688. see that this number never exceeds the usage count of the cred
  689. struct.
  690. Furthermore, if SELinux is enabled, this also checks that the
  691. security pointer in the cred struct is never seen to be invalid.
  692. If unsure, say N.
  693. #
  694. # Select this config option from the architecture Kconfig, if it
  695. # it is preferred to always offer frame pointers as a config
  696. # option on the architecture (regardless of KERNEL_DEBUG):
  697. #
  698. config ARCH_WANT_FRAME_POINTERS
  699. bool
  700. help
  701. config FRAME_POINTER
  702. bool "Compile the kernel with frame pointers"
  703. depends on DEBUG_KERNEL && \
  704. (CRIS || M68K || FRV || UML || \
  705. AVR32 || SUPERH || BLACKFIN || MN10300) || \
  706. ARCH_WANT_FRAME_POINTERS
  707. default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
  708. help
  709. If you say Y here the resulting kernel image will be slightly
  710. larger and slower, but it gives very useful debugging information
  711. in case of kernel bugs. (precise oopses/stacktraces/warnings)
  712. config BOOT_PRINTK_DELAY
  713. bool "Delay each boot printk message by N milliseconds"
  714. depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
  715. help
  716. This build option allows you to read kernel boot messages
  717. by inserting a short delay after each one. The delay is
  718. specified in milliseconds on the kernel command line,
  719. using "boot_delay=N".
  720. It is likely that you would also need to use "lpj=M" to preset
  721. the "loops per jiffie" value.
  722. See a previous boot log for the "lpj" value to use for your
  723. system, and then set "lpj=M" before setting "boot_delay=N".
  724. NOTE: Using this option may adversely affect SMP systems.
  725. I.e., processors other than the first one may not boot up.
  726. BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
  727. what it believes to be lockup conditions.
  728. config RCU_TORTURE_TEST
  729. tristate "torture tests for RCU"
  730. depends on DEBUG_KERNEL
  731. default n
  732. help
  733. This option provides a kernel module that runs torture tests
  734. on the RCU infrastructure. The kernel module may be built
  735. after the fact on the running kernel to be tested, if desired.
  736. Say Y here if you want RCU torture tests to be built into
  737. the kernel.
  738. Say M if you want the RCU torture tests to build as a module.
  739. Say N if you are unsure.
  740. config RCU_TORTURE_TEST_RUNNABLE
  741. bool "torture tests for RCU runnable by default"
  742. depends on RCU_TORTURE_TEST = y
  743. default n
  744. help
  745. This option provides a way to build the RCU torture tests
  746. directly into the kernel without them starting up at boot
  747. time. You can use /proc/sys/kernel/rcutorture_runnable
  748. to manually override this setting. This /proc file is
  749. available only when the RCU torture tests have been built
  750. into the kernel.
  751. Say Y here if you want the RCU torture tests to start during
  752. boot (you probably don't).
  753. Say N here if you want the RCU torture tests to start only
  754. after being manually enabled via /proc.
  755. config RCU_CPU_STALL_DETECTOR
  756. bool "Check for stalled CPUs delaying RCU grace periods"
  757. depends on TREE_RCU || TREE_PREEMPT_RCU
  758. default y
  759. help
  760. This option causes RCU to printk information on which
  761. CPUs are delaying the current grace period, but only when
  762. the grace period extends for excessive time periods.
  763. Say N if you want to disable such checks.
  764. Say Y if you are unsure.
  765. config RCU_CPU_STALL_TIMEOUT
  766. int "RCU CPU stall timeout in seconds"
  767. depends on RCU_CPU_STALL_DETECTOR
  768. range 3 300
  769. default 60
  770. help
  771. If a given RCU grace period extends more than the specified
  772. number of seconds, a CPU stall warning is printed. If the
  773. RCU grace period persists, additional CPU stall warnings are
  774. printed at more widely spaced intervals.
  775. config RCU_CPU_STALL_DETECTOR_RUNNABLE
  776. bool "RCU CPU stall checking starts automatically at boot"
  777. depends on RCU_CPU_STALL_DETECTOR
  778. default y
  779. help
  780. If set, start checking for RCU CPU stalls immediately on
  781. boot. Otherwise, RCU CPU stall checking must be manually
  782. enabled.
  783. Say Y if you are unsure.
  784. Say N if you wish to suppress RCU CPU stall checking during boot.
  785. config RCU_CPU_STALL_VERBOSE
  786. bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
  787. depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
  788. default y
  789. help
  790. This option causes RCU to printk detailed per-task information
  791. for any tasks that are stalling the current RCU grace period.
  792. Say N if you are unsure.
  793. Say Y if you want to enable such checks.
  794. config KPROBES_SANITY_TEST
  795. bool "Kprobes sanity tests"
  796. depends on DEBUG_KERNEL
  797. depends on KPROBES
  798. default n
  799. help
  800. This option provides for testing basic kprobes functionality on
  801. boot. A sample kprobe, jprobe and kretprobe are inserted and
  802. verified for functionality.
  803. Say N if you are unsure.
  804. config BACKTRACE_SELF_TEST
  805. tristate "Self test for the backtrace code"
  806. depends on DEBUG_KERNEL
  807. default n
  808. help
  809. This option provides a kernel module that can be used to test
  810. the kernel stack backtrace code. This option is not useful
  811. for distributions or general kernels, but only for kernel
  812. developers working on architecture code.
  813. Note that if you want to also test saved backtraces, you will
  814. have to enable STACKTRACE as well.
  815. Say N if you are unsure.
  816. config DEBUG_BLOCK_EXT_DEVT
  817. bool "Force extended block device numbers and spread them"
  818. depends on DEBUG_KERNEL
  819. depends on BLOCK
  820. default n
  821. help
  822. BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
  823. SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
  824. YOU ARE DOING. Distros, please enable this and fix whatever
  825. is broken.
  826. Conventionally, block device numbers are allocated from
  827. predetermined contiguous area. However, extended block area
  828. may introduce non-contiguous block device numbers. This
  829. option forces most block device numbers to be allocated from
  830. the extended space and spreads them to discover kernel or
  831. userland code paths which assume predetermined contiguous
  832. device number allocation.
  833. Note that turning on this debug option shuffles all the
  834. device numbers for all IDE and SCSI devices including libata
  835. ones, so root partition specified using device number
  836. directly (via rdev or root=MAJ:MIN) won't work anymore.
  837. Textual device names (root=/dev/sdXn) will continue to work.
  838. Say N if you are unsure.
  839. config DEBUG_FORCE_WEAK_PER_CPU
  840. bool "Force weak per-cpu definitions"
  841. depends on DEBUG_KERNEL
  842. help
  843. s390 and alpha require percpu variables in modules to be
  844. defined weak to work around addressing range issue which
  845. puts the following two restrictions on percpu variable
  846. definitions.
  847. 1. percpu symbols must be unique whether static or not
  848. 2. percpu variables can't be defined inside a function
  849. To ensure that generic code follows the above rules, this
  850. option forces all percpu variables to be defined as weak.
  851. config LKDTM
  852. tristate "Linux Kernel Dump Test Tool Module"
  853. depends on DEBUG_FS
  854. depends on BLOCK
  855. default n
  856. help
  857. This module enables testing of the different dumping mechanisms by
  858. inducing system failures at predefined crash points.
  859. If you don't need it: say N
  860. Choose M here to compile this code as a module. The module will be
  861. called lkdtm.
  862. Documentation on how to use the module can be found in
  863. Documentation/fault-injection/provoke-crashes.txt
  864. config CPU_NOTIFIER_ERROR_INJECT
  865. tristate "CPU notifier error injection module"
  866. depends on HOTPLUG_CPU && DEBUG_KERNEL
  867. help
  868. This option provides a kernel module that can be used to test
  869. the error handling of the cpu notifiers
  870. To compile this code as a module, choose M here: the module will
  871. be called cpu-notifier-error-inject.
  872. If unsure, say N.
  873. config FAULT_INJECTION
  874. bool "Fault-injection framework"
  875. depends on DEBUG_KERNEL
  876. help
  877. Provide fault-injection framework.
  878. For more details, see Documentation/fault-injection/.
  879. config FAILSLAB
  880. bool "Fault-injection capability for kmalloc"
  881. depends on FAULT_INJECTION
  882. depends on SLAB || SLUB
  883. help
  884. Provide fault-injection capability for kmalloc.
  885. config FAIL_PAGE_ALLOC
  886. bool "Fault-injection capabilitiy for alloc_pages()"
  887. depends on FAULT_INJECTION
  888. help
  889. Provide fault-injection capability for alloc_pages().
  890. config FAIL_MAKE_REQUEST
  891. bool "Fault-injection capability for disk IO"
  892. depends on FAULT_INJECTION && BLOCK
  893. help
  894. Provide fault-injection capability for disk IO.
  895. config FAIL_IO_TIMEOUT
  896. bool "Fault-injection capability for faking disk interrupts"
  897. depends on FAULT_INJECTION && BLOCK
  898. help
  899. Provide fault-injection capability on end IO handling. This
  900. will make the block layer "forget" an interrupt as configured,
  901. thus exercising the error handling.
  902. Only works with drivers that use the generic timeout handling,
  903. for others it wont do anything.
  904. config FAULT_INJECTION_DEBUG_FS
  905. bool "Debugfs entries for fault-injection capabilities"
  906. depends on FAULT_INJECTION && SYSFS && DEBUG_FS
  907. help
  908. Enable configuration of fault-injection capabilities via debugfs.
  909. config FAULT_INJECTION_STACKTRACE_FILTER
  910. bool "stacktrace filter for fault-injection capabilities"
  911. depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
  912. depends on !X86_64
  913. select STACKTRACE
  914. select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
  915. help
  916. Provide stacktrace filter for fault-injection capabilities
  917. config LATENCYTOP
  918. bool "Latency measuring infrastructure"
  919. depends on HAVE_LATENCYTOP_SUPPORT
  920. depends on DEBUG_KERNEL
  921. depends on STACKTRACE_SUPPORT
  922. depends on PROC_FS
  923. select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
  924. select KALLSYMS
  925. select KALLSYMS_ALL
  926. select STACKTRACE
  927. select SCHEDSTATS
  928. select SCHED_DEBUG
  929. help
  930. Enable this option if you want to use the LatencyTOP tool
  931. to find out which userspace is blocking on what kernel operations.
  932. config SYSCTL_SYSCALL_CHECK
  933. bool "Sysctl checks"
  934. depends on SYSCTL
  935. ---help---
  936. sys_sysctl uses binary paths that have been found challenging
  937. to properly maintain and use. This enables checks that help
  938. you to keep things correct.
  939. source mm/Kconfig.debug
  940. source kernel/trace/Kconfig
  941. config PROVIDE_OHCI1394_DMA_INIT
  942. bool "Remote debugging over FireWire early on boot"
  943. depends on PCI && X86
  944. help
  945. If you want to debug problems which hang or crash the kernel early
  946. on boot and the crashing machine has a FireWire port, you can use
  947. this feature to remotely access the memory of the crashed machine
  948. over FireWire. This employs remote DMA as part of the OHCI1394
  949. specification which is now the standard for FireWire controllers.
  950. With remote DMA, you can monitor the printk buffer remotely using
  951. firescope and access all memory below 4GB using fireproxy from gdb.
  952. Even controlling a kernel debugger is possible using remote DMA.
  953. Usage:
  954. If ohci1394_dma=early is used as boot parameter, it will initialize
  955. all OHCI1394 controllers which are found in the PCI config space.
  956. As all changes to the FireWire bus such as enabling and disabling
  957. devices cause a bus reset and thereby disable remote DMA for all
  958. devices, be sure to have the cable plugged and FireWire enabled on
  959. the debugging host before booting the debug target for debugging.
  960. This code (~1k) is freed after boot. By then, the firewire stack
  961. in charge of the OHCI-1394 controllers should be used instead.
  962. See Documentation/debugging-via-ohci1394.txt for more information.
  963. config FIREWIRE_OHCI_REMOTE_DMA
  964. bool "Remote debugging over FireWire with firewire-ohci"
  965. depends on FIREWIRE_OHCI
  966. help
  967. This option lets you use the FireWire bus for remote debugging
  968. with help of the firewire-ohci driver. It enables unfiltered
  969. remote DMA in firewire-ohci.
  970. See Documentation/debugging-via-ohci1394.txt for more information.
  971. If unsure, say N.
  972. config BUILD_DOCSRC
  973. bool "Build targets in Documentation/ tree"
  974. depends on HEADERS_CHECK
  975. help
  976. This option attempts to build objects from the source files in the
  977. kernel Documentation/ tree.
  978. Say N if you are unsure.
  979. config DYNAMIC_DEBUG
  980. bool "Enable dynamic printk() support"
  981. default n
  982. depends on PRINTK
  983. depends on DEBUG_FS
  984. help
  985. Compiles debug level messages into the kernel, which would not
  986. otherwise be available at runtime. These messages can then be
  987. enabled/disabled based on various levels of scope - per source file,
  988. function, module, format string, and line number. This mechanism
  989. implicitly enables all pr_debug() and dev_dbg() calls. The impact of
  990. this compile option is a larger kernel text size of about 2%.
  991. Usage:
  992. Dynamic debugging is controlled via the 'dynamic_debug/control' file,
  993. which is contained in the 'debugfs' filesystem. Thus, the debugfs
  994. filesystem must first be mounted before making use of this feature.
  995. We refer the control file as: <debugfs>/dynamic_debug/control. This
  996. file contains a list of the debug statements that can be enabled. The
  997. format for each line of the file is:
  998. filename:lineno [module]function flags format
  999. filename : source file of the debug statement
  1000. lineno : line number of the debug statement
  1001. module : module that contains the debug statement
  1002. function : function that contains the debug statement
  1003. flags : 'p' means the line is turned 'on' for printing
  1004. format : the format used for the debug statement
  1005. From a live system:
  1006. nullarbor:~ # cat <debugfs>/dynamic_debug/control
  1007. # filename:lineno [module]function flags format
  1008. fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
  1009. fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
  1010. fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
  1011. Example usage:
  1012. // enable the message at line 1603 of file svcsock.c
  1013. nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
  1014. <debugfs>/dynamic_debug/control
  1015. // enable all the messages in file svcsock.c
  1016. nullarbor:~ # echo -n 'file svcsock.c +p' >
  1017. <debugfs>/dynamic_debug/control
  1018. // enable all the messages in the NFS server module
  1019. nullarbor:~ # echo -n 'module nfsd +p' >
  1020. <debugfs>/dynamic_debug/control
  1021. // enable all 12 messages in the function svc_process()
  1022. nullarbor:~ # echo -n 'func svc_process +p' >
  1023. <debugfs>/dynamic_debug/control
  1024. // disable all 12 messages in the function svc_process()
  1025. nullarbor:~ # echo -n 'func svc_process -p' >
  1026. <debugfs>/dynamic_debug/control
  1027. See Documentation/dynamic-debug-howto.txt for additional information.
  1028. config DMA_API_DEBUG
  1029. bool "Enable debugging of DMA-API usage"
  1030. depends on HAVE_DMA_API_DEBUG
  1031. help
  1032. Enable this option to debug the use of the DMA API by device drivers.
  1033. With this option you will be able to detect common bugs in device
  1034. drivers like double-freeing of DMA mappings or freeing mappings that
  1035. were never allocated.
  1036. This option causes a performance degredation. Use only if you want
  1037. to debug device drivers. If unsure, say N.
  1038. config ATOMIC64_SELFTEST
  1039. bool "Perform an atomic64_t self-test at boot"
  1040. help
  1041. Enable this option to test the atomic64_t functions at boot.
  1042. If unsure, say N.
  1043. config ASYNC_RAID6_TEST
  1044. tristate "Self test for hardware accelerated raid6 recovery"
  1045. depends on ASYNC_RAID6_RECOV
  1046. select ASYNC_MEMCPY
  1047. ---help---
  1048. This is a one-shot self test that permutes through the
  1049. recovery of all the possible two disk failure scenarios for a
  1050. N-disk array. Recovery is performed with the asynchronous
  1051. raid6 recovery routines, and will optionally use an offload
  1052. engine if one is available.
  1053. If unsure, say N.
  1054. source "samples/Kconfig"
  1055. source "lib/Kconfig.kgdb"
  1056. source "lib/Kconfig.kmemcheck"
  1057. config TEST_KSTRTOX
  1058. tristate "Test kstrto*() family of functions at runtime"