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. Or add printk.time=1 at boot-time.
  10. See Documentation/kernel-parameters.txt
  11. config DEFAULT_MESSAGE_LOGLEVEL
  12. int "Default message log level (1-7)"
  13. range 1 7
  14. default "4"
  15. help
  16. Default log level for printk statements with no specified priority.
  17. This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
  18. that are auditing their logs closely may want to set it to a lower
  19. priority.
  20. config ENABLE_WARN_DEPRECATED
  21. bool "Enable __deprecated logic"
  22. default y
  23. help
  24. Enable the __deprecated logic in the kernel build.
  25. Disable this to suppress the "warning: 'foo' is deprecated
  26. (declared at kernel/power/somefile.c:1234)" messages.
  27. config ENABLE_MUST_CHECK
  28. bool "Enable __must_check logic"
  29. default y
  30. help
  31. Enable the __must_check logic in the kernel build. Disable this to
  32. suppress the "warning: ignoring return value of 'foo', declared with
  33. attribute warn_unused_result" messages.
  34. config FRAME_WARN
  35. int "Warn for stack frames larger than (needs gcc 4.4)"
  36. range 0 8192
  37. default 1024 if !64BIT
  38. default 2048 if 64BIT
  39. help
  40. Tell gcc to warn at build time for stack frames larger than this.
  41. Setting this too low will cause a lot of warnings.
  42. Setting it to 0 disables the warning.
  43. Requires gcc 4.4
  44. config MAGIC_SYSRQ
  45. bool "Magic SysRq key"
  46. depends on !UML
  47. help
  48. If you say Y here, you will have some control over the system even
  49. if the system crashes for example during kernel debugging (e.g., you
  50. will be able to flush the buffer cache to disk, reboot the system
  51. immediately or dump some status information). This is accomplished
  52. by pressing various keys while holding SysRq (Alt+PrintScreen). It
  53. also works on a serial console (on PC hardware at least), if you
  54. send a BREAK and then within 5 seconds a command keypress. The
  55. keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  56. unless you really know what this hack does.
  57. config STRIP_ASM_SYMS
  58. bool "Strip assembler-generated symbols during link"
  59. default n
  60. help
  61. Strip internal assembler-generated symbols during a link (symbols
  62. that look like '.Lxxx') so they don't pollute the output of
  63. get_wchan() and suchlike.
  64. config UNUSED_SYMBOLS
  65. bool "Enable unused/obsolete exported symbols"
  66. default y if X86
  67. help
  68. Unused but exported symbols make the kernel needlessly bigger. For
  69. that reason most of these unused exports will soon be removed. This
  70. option is provided temporarily to provide a transition period in case
  71. some external kernel module needs one of these symbols anyway. If you
  72. encounter such a case in your module, consider if you are actually
  73. using the right API. (rationale: since nobody in the kernel is using
  74. this in a module, there is a pretty good chance it's actually the
  75. wrong interface to use). If you really need the symbol, please send a
  76. mail to the linux kernel mailing list mentioning the symbol and why
  77. you really need it, and what the merge plan to the mainline kernel for
  78. your module is.
  79. config DEBUG_FS
  80. bool "Debug Filesystem"
  81. help
  82. debugfs is a virtual file system that kernel developers use to put
  83. debugging files into. Enable this option to be able to read and
  84. write to these files.
  85. For detailed documentation on the debugfs API, see
  86. Documentation/DocBook/filesystems.
  87. If unsure, say N.
  88. config HEADERS_CHECK
  89. bool "Run 'make headers_check' when building vmlinux"
  90. depends on !UML
  91. help
  92. This option will extract the user-visible kernel headers whenever
  93. building the kernel, and will run basic sanity checks on them to
  94. ensure that exported files do not attempt to include files which
  95. were not exported, etc.
  96. If you're making modifications to header files which are
  97. relevant for userspace, say 'Y', and check the headers
  98. exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  99. your build tree), to make sure they're suitable.
  100. config DEBUG_SECTION_MISMATCH
  101. bool "Enable full Section mismatch analysis"
  102. help
  103. The section mismatch analysis checks if there are illegal
  104. references from one section to another section.
  105. Linux will during link or during runtime drop some sections
  106. and any use of code/data previously in these sections will
  107. most likely result in an oops.
  108. In the code functions and variables are annotated with
  109. __init, __devinit etc. (see full list in include/linux/init.h)
  110. which results in the code/data being placed in specific sections.
  111. The section mismatch analysis is always done after a full
  112. kernel build but enabling this option will in addition
  113. do the following:
  114. - Add the option -fno-inline-functions-called-once to gcc
  115. When inlining a function annotated __init in a non-init
  116. function we would lose the section information and thus
  117. the analysis would not catch the illegal reference.
  118. This option tells gcc to inline less but will also
  119. result in a larger kernel.
  120. - Run the section mismatch analysis for each module/built-in.o
  121. When we run the section mismatch analysis on vmlinux.o we
  122. lose valueble information about where the mismatch was
  123. introduced.
  124. Running the analysis for each module/built-in.o file
  125. will tell where the mismatch happens much closer to the
  126. source. The drawback is that we will report the same
  127. mismatch at least twice.
  128. - Enable verbose reporting from modpost to help solving
  129. the section mismatches reported.
  130. config DEBUG_KERNEL
  131. bool "Kernel debugging"
  132. help
  133. Say Y here if you are developing drivers or trying to debug and
  134. identify kernel problems.
  135. config DEBUG_SHIRQ
  136. bool "Debug shared IRQ handlers"
  137. depends on DEBUG_KERNEL && GENERIC_HARDIRQS
  138. help
  139. Enable this to generate a spurious interrupt as soon as a shared
  140. interrupt handler is registered, and just before one is deregistered.
  141. Drivers ought to be able to handle interrupts coming in at those
  142. points; some don't and need to be caught.
  143. config LOCKUP_DETECTOR
  144. bool "Detect Hard and Soft Lockups"
  145. depends on DEBUG_KERNEL && !S390
  146. help
  147. Say Y here to enable the kernel to act as a watchdog to detect
  148. hard and soft lockups.
  149. Softlockups are bugs that cause the kernel to loop in kernel
  150. mode for more than 60 seconds, without giving other tasks a
  151. chance to run. The current stack trace is displayed upon
  152. detection and the system will stay locked up.
  153. Hardlockups are bugs that cause the CPU to loop in kernel mode
  154. for more than 60 seconds, without letting other interrupts have a
  155. chance to run. The current stack trace is displayed upon detection
  156. and the system will stay locked up.
  157. The overhead should be minimal. A periodic hrtimer runs to
  158. generate interrupts and kick the watchdog task every 10-12 seconds.
  159. An NMI is generated every 60 seconds or so to check for hardlockups.
  160. config HARDLOCKUP_DETECTOR
  161. def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
  162. !ARCH_HAS_NMI_WATCHDOG
  163. config BOOTPARAM_HARDLOCKUP_PANIC
  164. bool "Panic (Reboot) On Hard Lockups"
  165. depends on LOCKUP_DETECTOR
  166. help
  167. Say Y here to enable the kernel to panic on "hard lockups",
  168. which are bugs that cause the kernel to loop in kernel
  169. mode with interrupts disabled for more than 60 seconds.
  170. Say N if unsure.
  171. config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
  172. int
  173. depends on LOCKUP_DETECTOR
  174. range 0 1
  175. default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
  176. default 1 if BOOTPARAM_HARDLOCKUP_PANIC
  177. config BOOTPARAM_SOFTLOCKUP_PANIC
  178. bool "Panic (Reboot) On Soft Lockups"
  179. depends on LOCKUP_DETECTOR
  180. help
  181. Say Y here to enable the kernel to panic on "soft lockups",
  182. which are bugs that cause the kernel to loop in kernel
  183. mode for more than 60 seconds, without giving other tasks a
  184. chance to run.
  185. The panic can be used in combination with panic_timeout,
  186. to cause the system to reboot automatically after a
  187. lockup has been detected. This feature is useful for
  188. high-availability systems that have uptime guarantees and
  189. where a lockup must be resolved ASAP.
  190. Say N if unsure.
  191. config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
  192. int
  193. depends on LOCKUP_DETECTOR
  194. range 0 1
  195. default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
  196. default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
  197. config DETECT_HUNG_TASK
  198. bool "Detect Hung Tasks"
  199. depends on DEBUG_KERNEL
  200. default DETECT_SOFTLOCKUP
  201. help
  202. Say Y here to enable the kernel to detect "hung tasks",
  203. which are bugs that cause the task to be stuck in
  204. uninterruptible "D" state indefinitiley.
  205. When a hung task is detected, the kernel will print the
  206. current stack trace (which you should report), but the
  207. task will stay in uninterruptible state. If lockdep is
  208. enabled then all held locks will also be reported. This
  209. feature has negligible overhead.
  210. config DEFAULT_HUNG_TASK_TIMEOUT
  211. int "Default timeout for hung task detection (in seconds)"
  212. depends on DETECT_HUNG_TASK
  213. default 120
  214. help
  215. This option controls the default timeout (in seconds) used
  216. to determine when a task has become non-responsive and should
  217. be considered hung.
  218. It can be adjusted at runtime via the kernel.hung_task_timeout
  219. sysctl or by writing a value to /proc/sys/kernel/hung_task_timeout.
  220. A timeout of 0 disables the check. The default is two minutes.
  221. Keeping the default should be fine in most cases.
  222. config BOOTPARAM_HUNG_TASK_PANIC
  223. bool "Panic (Reboot) On Hung Tasks"
  224. depends on DETECT_HUNG_TASK
  225. help
  226. Say Y here to enable the kernel to panic on "hung tasks",
  227. which are bugs that cause the kernel to leave a task stuck
  228. in uninterruptible "D" state.
  229. The panic can be used in combination with panic_timeout,
  230. to cause the system to reboot automatically after a
  231. hung task has been detected. This feature is useful for
  232. high-availability systems that have uptime guarantees and
  233. where a hung tasks must be resolved ASAP.
  234. Say N if unsure.
  235. config BOOTPARAM_HUNG_TASK_PANIC_VALUE
  236. int
  237. depends on DETECT_HUNG_TASK
  238. range 0 1
  239. default 0 if !BOOTPARAM_HUNG_TASK_PANIC
  240. default 1 if BOOTPARAM_HUNG_TASK_PANIC
  241. config SCHED_DEBUG
  242. bool "Collect scheduler debugging info"
  243. depends on DEBUG_KERNEL && PROC_FS
  244. default y
  245. help
  246. If you say Y here, the /proc/sched_debug file will be provided
  247. that can help debug the scheduler. The runtime overhead of this
  248. option is minimal.
  249. config SCHEDSTATS
  250. bool "Collect scheduler statistics"
  251. depends on DEBUG_KERNEL && PROC_FS
  252. help
  253. If you say Y here, additional code will be inserted into the
  254. scheduler and related routines to collect statistics about
  255. scheduler behavior and provide them in /proc/schedstat. These
  256. stats may be useful for both tuning and debugging the scheduler
  257. If you aren't debugging the scheduler or trying to tune a specific
  258. application, you can say N to avoid the very slight overhead
  259. this adds.
  260. config TIMER_STATS
  261. bool "Collect kernel timers statistics"
  262. depends on DEBUG_KERNEL && PROC_FS
  263. help
  264. If you say Y here, additional code will be inserted into the
  265. timer routines to collect statistics about kernel timers being
  266. reprogrammed. The statistics can be read from /proc/timer_stats.
  267. The statistics collection is started by writing 1 to /proc/timer_stats,
  268. writing 0 stops it. This feature is useful to collect information
  269. about timer usage patterns in kernel and userspace. This feature
  270. is lightweight if enabled in the kernel config but not activated
  271. (it defaults to deactivated on bootup and will only be activated
  272. if some application like powertop activates it explicitly).
  273. config DEBUG_OBJECTS
  274. bool "Debug object operations"
  275. depends on DEBUG_KERNEL
  276. help
  277. If you say Y here, additional code will be inserted into the
  278. kernel to track the life time of various objects and validate
  279. the operations on those objects.
  280. config DEBUG_OBJECTS_SELFTEST
  281. bool "Debug objects selftest"
  282. depends on DEBUG_OBJECTS
  283. help
  284. This enables the selftest of the object debug code.
  285. config DEBUG_OBJECTS_FREE
  286. bool "Debug objects in freed memory"
  287. depends on DEBUG_OBJECTS
  288. help
  289. This enables checks whether a k/v free operation frees an area
  290. which contains an object which has not been deactivated
  291. properly. This can make kmalloc/kfree-intensive workloads
  292. much slower.
  293. config DEBUG_OBJECTS_TIMERS
  294. bool "Debug timer objects"
  295. depends on DEBUG_OBJECTS
  296. help
  297. If you say Y here, additional code will be inserted into the
  298. timer routines to track the life time of timer objects and
  299. validate the timer operations.
  300. config DEBUG_OBJECTS_WORK
  301. bool "Debug work objects"
  302. depends on DEBUG_OBJECTS
  303. help
  304. If you say Y here, additional code will be inserted into the
  305. work queue routines to track the life time of work objects and
  306. validate the work operations.
  307. config DEBUG_OBJECTS_RCU_HEAD
  308. bool "Debug RCU callbacks objects"
  309. depends on DEBUG_OBJECTS
  310. help
  311. Enable this to turn on debugging of RCU list heads (call_rcu() usage).
  312. config DEBUG_OBJECTS_PERCPU_COUNTER
  313. bool "Debug percpu counter objects"
  314. depends on DEBUG_OBJECTS
  315. help
  316. If you say Y here, additional code will be inserted into the
  317. percpu counter routines to track the life time of percpu counter
  318. objects and validate the percpu counter operations.
  319. config DEBUG_OBJECTS_ENABLE_DEFAULT
  320. int "debug_objects bootup default value (0-1)"
  321. range 0 1
  322. default "1"
  323. depends on DEBUG_OBJECTS
  324. help
  325. Debug objects boot parameter default value
  326. config DEBUG_SLAB
  327. bool "Debug slab memory allocations"
  328. depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
  329. help
  330. Say Y here to have the kernel do limited verification on memory
  331. allocation as well as poisoning memory on free to catch use of freed
  332. memory. This can make kmalloc/kfree-intensive workloads much slower.
  333. config DEBUG_SLAB_LEAK
  334. bool "Memory leak debugging"
  335. depends on DEBUG_SLAB
  336. config SLUB_DEBUG_ON
  337. bool "SLUB debugging on by default"
  338. depends on SLUB && SLUB_DEBUG && !KMEMCHECK
  339. default n
  340. help
  341. Boot with debugging on by default. SLUB boots by default with
  342. the runtime debug capabilities switched off. Enabling this is
  343. equivalent to specifying the "slub_debug" parameter on boot.
  344. There is no support for more fine grained debug control like
  345. possible with slub_debug=xxx. SLUB debugging may be switched
  346. off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
  347. "slub_debug=-".
  348. config SLUB_STATS
  349. default n
  350. bool "Enable SLUB performance statistics"
  351. depends on SLUB && SYSFS
  352. help
  353. SLUB statistics are useful to debug SLUBs allocation behavior in
  354. order find ways to optimize the allocator. This should never be
  355. enabled for production use since keeping statistics slows down
  356. the allocator by a few percentage points. The slabinfo command
  357. supports the determination of the most active slabs to figure
  358. out which slabs are relevant to a particular load.
  359. Try running: slabinfo -DA
  360. config DEBUG_KMEMLEAK
  361. bool "Kernel memory leak detector"
  362. depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
  363. (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
  364. select DEBUG_FS
  365. select STACKTRACE if STACKTRACE_SUPPORT
  366. select KALLSYMS
  367. select CRC32
  368. help
  369. Say Y here if you want to enable the memory leak
  370. detector. The memory allocation/freeing is traced in a way
  371. similar to the Boehm's conservative garbage collector, the
  372. difference being that the orphan objects are not freed but
  373. only shown in /sys/kernel/debug/kmemleak. Enabling this
  374. feature will introduce an overhead to memory
  375. allocations. See Documentation/kmemleak.txt for more
  376. details.
  377. Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
  378. of finding leaks due to the slab objects poisoning.
  379. In order to access the kmemleak file, debugfs needs to be
  380. mounted (usually at /sys/kernel/debug).
  381. config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
  382. int "Maximum kmemleak early log entries"
  383. depends on DEBUG_KMEMLEAK
  384. range 200 40000
  385. default 400
  386. help
  387. Kmemleak must track all the memory allocations to avoid
  388. reporting false positives. Since memory may be allocated or
  389. freed before kmemleak is initialised, an early log buffer is
  390. used to store these actions. If kmemleak reports "early log
  391. buffer exceeded", please increase this value.
  392. config DEBUG_KMEMLEAK_TEST
  393. tristate "Simple test for the kernel memory leak detector"
  394. depends on DEBUG_KMEMLEAK && m
  395. help
  396. This option enables a module that explicitly leaks memory.
  397. If unsure, say N.
  398. config DEBUG_KMEMLEAK_DEFAULT_OFF
  399. bool "Default kmemleak to off"
  400. depends on DEBUG_KMEMLEAK
  401. help
  402. Say Y here to disable kmemleak by default. It can then be enabled
  403. on the command line via kmemleak=on.
  404. config DEBUG_PREEMPT
  405. bool "Debug preemptible kernel"
  406. depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
  407. default y
  408. help
  409. If you say Y here then the kernel will use a debug variant of the
  410. commonly used smp_processor_id() function and will print warnings
  411. if kernel code uses it in a preemption-unsafe way. Also, the kernel
  412. will detect preemption count underflows.
  413. config DEBUG_RT_MUTEXES
  414. bool "RT Mutex debugging, deadlock detection"
  415. depends on DEBUG_KERNEL && RT_MUTEXES
  416. help
  417. This allows rt mutex semantics violations and rt mutex related
  418. deadlocks (lockups) to be detected and reported automatically.
  419. config DEBUG_PI_LIST
  420. bool
  421. default y
  422. depends on DEBUG_RT_MUTEXES
  423. config RT_MUTEX_TESTER
  424. bool "Built-in scriptable tester for rt-mutexes"
  425. depends on DEBUG_KERNEL && RT_MUTEXES
  426. help
  427. This option enables a rt-mutex tester.
  428. config DEBUG_SPINLOCK
  429. bool "Spinlock and rw-lock debugging: basic checks"
  430. depends on DEBUG_KERNEL
  431. help
  432. Say Y here and build SMP to catch missing spinlock initialization
  433. and certain other kinds of spinlock errors commonly made. This is
  434. best used in conjunction with the NMI watchdog so that spinlock
  435. deadlocks are also debuggable.
  436. config DEBUG_MUTEXES
  437. bool "Mutex debugging: basic checks"
  438. depends on DEBUG_KERNEL
  439. help
  440. This feature allows mutex semantics violations to be detected and
  441. reported.
  442. config DEBUG_LOCK_ALLOC
  443. bool "Lock debugging: detect incorrect freeing of live locks"
  444. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  445. select DEBUG_SPINLOCK
  446. select DEBUG_MUTEXES
  447. select LOCKDEP
  448. help
  449. This feature will check whether any held lock (spinlock, rwlock,
  450. mutex or rwsem) is incorrectly freed by the kernel, via any of the
  451. memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
  452. vfree(), etc.), whether a live lock is incorrectly reinitialized via
  453. spin_lock_init()/mutex_init()/etc., or whether there is any lock
  454. held during task exit.
  455. config PROVE_LOCKING
  456. bool "Lock debugging: prove locking correctness"
  457. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  458. select LOCKDEP
  459. select DEBUG_SPINLOCK
  460. select DEBUG_MUTEXES
  461. select DEBUG_LOCK_ALLOC
  462. select TRACE_IRQFLAGS
  463. default n
  464. help
  465. This feature enables the kernel to prove that all locking
  466. that occurs in the kernel runtime is mathematically
  467. correct: that under no circumstance could an arbitrary (and
  468. not yet triggered) combination of observed locking
  469. sequences (on an arbitrary number of CPUs, running an
  470. arbitrary number of tasks and interrupt contexts) cause a
  471. deadlock.
  472. In short, this feature enables the kernel to report locking
  473. related deadlocks before they actually occur.
  474. The proof does not depend on how hard and complex a
  475. deadlock scenario would be to trigger: how many
  476. participant CPUs, tasks and irq-contexts would be needed
  477. for it to trigger. The proof also does not depend on
  478. timing: if a race and a resulting deadlock is possible
  479. theoretically (no matter how unlikely the race scenario
  480. is), it will be proven so and will immediately be
  481. reported by the kernel (once the event is observed that
  482. makes the deadlock theoretically possible).
  483. If a deadlock is impossible (i.e. the locking rules, as
  484. observed by the kernel, are mathematically correct), the
  485. kernel reports nothing.
  486. NOTE: this feature can also be enabled for rwlocks, mutexes
  487. and rwsems - in which case all dependencies between these
  488. different locking variants are observed and mapped too, and
  489. the proof of observed correctness is also maintained for an
  490. arbitrary combination of these separate locking variants.
  491. For more details, see Documentation/lockdep-design.txt.
  492. config PROVE_RCU
  493. bool "RCU debugging: prove RCU correctness"
  494. depends on PROVE_LOCKING
  495. default n
  496. help
  497. This feature enables lockdep extensions that check for correct
  498. use of RCU APIs. This is currently under development. Say Y
  499. if you want to debug RCU usage or help work on the PROVE_RCU
  500. feature.
  501. Say N if you are unsure.
  502. config PROVE_RCU_REPEATEDLY
  503. bool "RCU debugging: don't disable PROVE_RCU on first splat"
  504. depends on PROVE_RCU
  505. default n
  506. help
  507. By itself, PROVE_RCU will disable checking upon issuing the
  508. first warning (or "splat"). This feature prevents such
  509. disabling, allowing multiple RCU-lockdep warnings to be printed
  510. on a single reboot.
  511. Say Y to allow multiple RCU-lockdep warnings per boot.
  512. Say N if you are unsure.
  513. config SPARSE_RCU_POINTER
  514. bool "RCU debugging: sparse-based checks for pointer usage"
  515. default n
  516. help
  517. This feature enables the __rcu sparse annotation for
  518. RCU-protected pointers. This annotation will cause sparse
  519. to flag any non-RCU used of annotated pointers. This can be
  520. helpful when debugging RCU usage. Please note that this feature
  521. is not intended to enforce code cleanliness; it is instead merely
  522. a debugging aid.
  523. Say Y to make sparse flag questionable use of RCU-protected pointers
  524. Say N if you are unsure.
  525. config LOCKDEP
  526. bool
  527. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  528. select STACKTRACE
  529. select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
  530. select KALLSYMS
  531. select KALLSYMS_ALL
  532. config LOCK_STAT
  533. bool "Lock usage statistics"
  534. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  535. select LOCKDEP
  536. select DEBUG_SPINLOCK
  537. select DEBUG_MUTEXES
  538. select DEBUG_LOCK_ALLOC
  539. default n
  540. help
  541. This feature enables tracking lock contention points
  542. For more details, see Documentation/lockstat.txt
  543. This also enables lock events required by "perf lock",
  544. subcommand of perf.
  545. If you want to use "perf lock", you also need to turn on
  546. CONFIG_EVENT_TRACING.
  547. CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
  548. (CONFIG_LOCKDEP defines "acquire" and "release" events.)
  549. config DEBUG_LOCKDEP
  550. bool "Lock dependency engine debugging"
  551. depends on DEBUG_KERNEL && LOCKDEP
  552. help
  553. If you say Y here, the lock dependency engine will do
  554. additional runtime checks to debug itself, at the price
  555. of more runtime overhead.
  556. config TRACE_IRQFLAGS
  557. bool
  558. help
  559. Enables hooks to interrupt enabling and disabling for
  560. either tracing or lock debugging.
  561. config DEBUG_SPINLOCK_SLEEP
  562. bool "Spinlock debugging: sleep-inside-spinlock checking"
  563. depends on DEBUG_KERNEL
  564. help
  565. If you say Y here, various routines which may sleep will become very
  566. noisy if they are called with a spinlock held.
  567. config DEBUG_LOCKING_API_SELFTESTS
  568. bool "Locking API boot-time self-tests"
  569. depends on DEBUG_KERNEL
  570. help
  571. Say Y here if you want the kernel to run a short self-test during
  572. bootup. The self-test checks whether common types of locking bugs
  573. are detected by debugging mechanisms or not. (if you disable
  574. lock debugging then those bugs wont be detected of course.)
  575. The following locking APIs are covered: spinlocks, rwlocks,
  576. mutexes and rwsems.
  577. config STACKTRACE
  578. bool "Stacktrace"
  579. depends on STACKTRACE_SUPPORT
  580. default y
  581. config DEBUG_STACK_USAGE
  582. bool "Stack utilization instrumentation"
  583. depends on DEBUG_KERNEL
  584. help
  585. Enables the display of the minimum amount of free stack which each
  586. task has ever had available in the sysrq-T and sysrq-P debug output.
  587. This option will slow down process creation somewhat.
  588. config DEBUG_KOBJECT
  589. bool "kobject debugging"
  590. depends on DEBUG_KERNEL
  591. help
  592. If you say Y here, some extra kobject debugging messages will be sent
  593. to the syslog.
  594. config DEBUG_HIGHMEM
  595. bool "Highmem debugging"
  596. depends on DEBUG_KERNEL && HIGHMEM
  597. help
  598. This options enables addition error checking for high memory systems.
  599. Disable for production systems.
  600. config DEBUG_BUGVERBOSE
  601. bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
  602. depends on BUG
  603. depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
  604. FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || TILE
  605. default y
  606. help
  607. Say Y here to make BUG() panics output the file name and line number
  608. of the BUG call as well as the EIP and oops trace. This aids
  609. debugging but costs about 70-100K of memory.
  610. config DEBUG_INFO
  611. bool "Compile the kernel with debug info"
  612. depends on DEBUG_KERNEL
  613. help
  614. If you say Y here the resulting kernel image will include
  615. debugging info resulting in a larger kernel image.
  616. This adds debug symbols to the kernel and modules (gcc -g), and
  617. is needed if you intend to use kernel crashdump or binary object
  618. tools like crash, kgdb, LKCD, gdb, etc on the kernel.
  619. Say Y here only if you plan to debug the kernel.
  620. If unsure, say N.
  621. config DEBUG_INFO_REDUCED
  622. bool "Reduce debugging information"
  623. depends on DEBUG_INFO
  624. help
  625. If you say Y here gcc is instructed to generate less debugging
  626. information for structure types. This means that tools that
  627. need full debugging information (like kgdb or systemtap) won't
  628. be happy. But if you merely need debugging information to
  629. resolve line numbers there is no loss. Advantage is that
  630. build directory object sizes shrink dramatically over a full
  631. DEBUG_INFO build and compile times are reduced too.
  632. Only works with newer gcc versions.
  633. config DEBUG_VM
  634. bool "Debug VM"
  635. depends on DEBUG_KERNEL
  636. help
  637. Enable this to turn on extended checks in the virtual-memory system
  638. that may impact performance.
  639. If unsure, say N.
  640. config DEBUG_VIRTUAL
  641. bool "Debug VM translations"
  642. depends on DEBUG_KERNEL && X86
  643. help
  644. Enable some costly sanity checks in virtual to page code. This can
  645. catch mistakes with virt_to_page() and friends.
  646. If unsure, say N.
  647. config DEBUG_NOMMU_REGIONS
  648. bool "Debug the global anon/private NOMMU mapping region tree"
  649. depends on DEBUG_KERNEL && !MMU
  650. help
  651. This option causes the global tree of anonymous and private mapping
  652. regions to be regularly checked for invalid topology.
  653. config DEBUG_WRITECOUNT
  654. bool "Debug filesystem writers count"
  655. depends on DEBUG_KERNEL
  656. help
  657. Enable this to catch wrong use of the writers count in struct
  658. vfsmount. This will increase the size of each file struct by
  659. 32 bits.
  660. If unsure, say N.
  661. config DEBUG_MEMORY_INIT
  662. bool "Debug memory initialisation" if EXPERT
  663. default !EXPERT
  664. help
  665. Enable this for additional checks during memory initialisation.
  666. The sanity checks verify aspects of the VM such as the memory model
  667. and other information provided by the architecture. Verbose
  668. information will be printed at KERN_DEBUG loglevel depending
  669. on the mminit_loglevel= command-line option.
  670. If unsure, say Y
  671. config DEBUG_LIST
  672. bool "Debug linked list manipulation"
  673. depends on DEBUG_KERNEL
  674. help
  675. Enable this to turn on extended checks in the linked-list
  676. walking routines.
  677. If unsure, say N.
  678. config TEST_LIST_SORT
  679. bool "Linked list sorting test"
  680. depends on DEBUG_KERNEL
  681. help
  682. Enable this to turn on 'list_sort()' function test. This test is
  683. executed only once during system boot, so affects only boot time.
  684. If unsure, say N.
  685. config DEBUG_SG
  686. bool "Debug SG table operations"
  687. depends on DEBUG_KERNEL
  688. help
  689. Enable this to turn on checks on scatter-gather tables. This can
  690. help find problems with drivers that do not properly initialize
  691. their sg tables.
  692. If unsure, say N.
  693. config DEBUG_NOTIFIERS
  694. bool "Debug notifier call chains"
  695. depends on DEBUG_KERNEL
  696. help
  697. Enable this to turn on sanity checking for notifier call chains.
  698. This is most useful for kernel developers to make sure that
  699. modules properly unregister themselves from notifier chains.
  700. This is a relatively cheap check but if you care about maximum
  701. performance, say N.
  702. config DEBUG_CREDENTIALS
  703. bool "Debug credential management"
  704. depends on DEBUG_KERNEL
  705. help
  706. Enable this to turn on some debug checking for credential
  707. management. The additional code keeps track of the number of
  708. pointers from task_structs to any given cred struct, and checks to
  709. see that this number never exceeds the usage count of the cred
  710. struct.
  711. Furthermore, if SELinux is enabled, this also checks that the
  712. security pointer in the cred struct is never seen to be invalid.
  713. If unsure, say N.
  714. #
  715. # Select this config option from the architecture Kconfig, if it
  716. # it is preferred to always offer frame pointers as a config
  717. # option on the architecture (regardless of KERNEL_DEBUG):
  718. #
  719. config ARCH_WANT_FRAME_POINTERS
  720. bool
  721. help
  722. config FRAME_POINTER
  723. bool "Compile the kernel with frame pointers"
  724. depends on DEBUG_KERNEL && \
  725. (CRIS || M68K || FRV || UML || \
  726. AVR32 || SUPERH || BLACKFIN || MN10300) || \
  727. ARCH_WANT_FRAME_POINTERS
  728. default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
  729. help
  730. If you say Y here the resulting kernel image will be slightly
  731. larger and slower, but it gives very useful debugging information
  732. in case of kernel bugs. (precise oopses/stacktraces/warnings)
  733. config BOOT_PRINTK_DELAY
  734. bool "Delay each boot printk message by N milliseconds"
  735. depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
  736. help
  737. This build option allows you to read kernel boot messages
  738. by inserting a short delay after each one. The delay is
  739. specified in milliseconds on the kernel command line,
  740. using "boot_delay=N".
  741. It is likely that you would also need to use "lpj=M" to preset
  742. the "loops per jiffie" value.
  743. See a previous boot log for the "lpj" value to use for your
  744. system, and then set "lpj=M" before setting "boot_delay=N".
  745. NOTE: Using this option may adversely affect SMP systems.
  746. I.e., processors other than the first one may not boot up.
  747. BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
  748. what it believes to be lockup conditions.
  749. config RCU_TORTURE_TEST
  750. tristate "torture tests for RCU"
  751. depends on DEBUG_KERNEL
  752. default n
  753. help
  754. This option provides a kernel module that runs torture tests
  755. on the RCU infrastructure. The kernel module may be built
  756. after the fact on the running kernel to be tested, if desired.
  757. Say Y here if you want RCU torture tests to be built into
  758. the kernel.
  759. Say M if you want the RCU torture tests to build as a module.
  760. Say N if you are unsure.
  761. config RCU_TORTURE_TEST_RUNNABLE
  762. bool "torture tests for RCU runnable by default"
  763. depends on RCU_TORTURE_TEST = y
  764. default n
  765. help
  766. This option provides a way to build the RCU torture tests
  767. directly into the kernel without them starting up at boot
  768. time. You can use /proc/sys/kernel/rcutorture_runnable
  769. to manually override this setting. This /proc file is
  770. available only when the RCU torture tests have been built
  771. into the kernel.
  772. Say Y here if you want the RCU torture tests to start during
  773. boot (you probably don't).
  774. Say N here if you want the RCU torture tests to start only
  775. after being manually enabled via /proc.
  776. config RCU_CPU_STALL_TIMEOUT
  777. int "RCU CPU stall timeout in seconds"
  778. depends on TREE_RCU || TREE_PREEMPT_RCU
  779. range 3 300
  780. default 60
  781. help
  782. If a given RCU grace period extends more than the specified
  783. number of seconds, a CPU stall warning is printed. If the
  784. RCU grace period persists, additional CPU stall warnings are
  785. printed at more widely spaced intervals.
  786. config RCU_CPU_STALL_VERBOSE
  787. bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
  788. depends on TREE_PREEMPT_RCU
  789. default y
  790. help
  791. This option causes RCU to printk detailed per-task information
  792. for any tasks that are stalling the current RCU grace period.
  793. Say N if you are unsure.
  794. Say Y if you want to enable such checks.
  795. config KPROBES_SANITY_TEST
  796. bool "Kprobes sanity tests"
  797. depends on DEBUG_KERNEL
  798. depends on KPROBES
  799. default n
  800. help
  801. This option provides for testing basic kprobes functionality on
  802. boot. A sample kprobe, jprobe and kretprobe are inserted and
  803. verified for functionality.
  804. Say N if you are unsure.
  805. config BACKTRACE_SELF_TEST
  806. tristate "Self test for the backtrace code"
  807. depends on DEBUG_KERNEL
  808. default n
  809. help
  810. This option provides a kernel module that can be used to test
  811. the kernel stack backtrace code. This option is not useful
  812. for distributions or general kernels, but only for kernel
  813. developers working on architecture code.
  814. Note that if you want to also test saved backtraces, you will
  815. have to enable STACKTRACE as well.
  816. Say N if you are unsure.
  817. config DEBUG_BLOCK_EXT_DEVT
  818. bool "Force extended block device numbers and spread them"
  819. depends on DEBUG_KERNEL
  820. depends on BLOCK
  821. default n
  822. help
  823. BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
  824. SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
  825. YOU ARE DOING. Distros, please enable this and fix whatever
  826. is broken.
  827. Conventionally, block device numbers are allocated from
  828. predetermined contiguous area. However, extended block area
  829. may introduce non-contiguous block device numbers. This
  830. option forces most block device numbers to be allocated from
  831. the extended space and spreads them to discover kernel or
  832. userland code paths which assume predetermined contiguous
  833. device number allocation.
  834. Note that turning on this debug option shuffles all the
  835. device numbers for all IDE and SCSI devices including libata
  836. ones, so root partition specified using device number
  837. directly (via rdev or root=MAJ:MIN) won't work anymore.
  838. Textual device names (root=/dev/sdXn) will continue to work.
  839. Say N if you are unsure.
  840. config DEBUG_FORCE_WEAK_PER_CPU
  841. bool "Force weak per-cpu definitions"
  842. depends on DEBUG_KERNEL
  843. help
  844. s390 and alpha require percpu variables in modules to be
  845. defined weak to work around addressing range issue which
  846. puts the following two restrictions on percpu variable
  847. definitions.
  848. 1. percpu symbols must be unique whether static or not
  849. 2. percpu variables can't be defined inside a function
  850. To ensure that generic code follows the above rules, this
  851. option forces all percpu variables to be defined as weak.
  852. config DEBUG_PER_CPU_MAPS
  853. bool "Debug access to per_cpu maps"
  854. depends on DEBUG_KERNEL
  855. depends on SMP
  856. help
  857. Say Y to verify that the per_cpu map being accessed has
  858. been set up. This adds a fair amount of code to kernel memory
  859. and decreases performance.
  860. Say N if unsure.
  861. config LKDTM
  862. tristate "Linux Kernel Dump Test Tool Module"
  863. depends on DEBUG_FS
  864. depends on BLOCK
  865. default n
  866. help
  867. This module enables testing of the different dumping mechanisms by
  868. inducing system failures at predefined crash points.
  869. If you don't need it: say N
  870. Choose M here to compile this code as a module. The module will be
  871. called lkdtm.
  872. Documentation on how to use the module can be found in
  873. Documentation/fault-injection/provoke-crashes.txt
  874. config CPU_NOTIFIER_ERROR_INJECT
  875. tristate "CPU notifier error injection module"
  876. depends on HOTPLUG_CPU && DEBUG_KERNEL
  877. help
  878. This option provides a kernel module that can be used to test
  879. the error handling of the cpu notifiers
  880. To compile this code as a module, choose M here: the module will
  881. be called cpu-notifier-error-inject.
  882. If unsure, say N.
  883. config FAULT_INJECTION
  884. bool "Fault-injection framework"
  885. depends on DEBUG_KERNEL
  886. help
  887. Provide fault-injection framework.
  888. For more details, see Documentation/fault-injection/.
  889. config FAILSLAB
  890. bool "Fault-injection capability for kmalloc"
  891. depends on FAULT_INJECTION
  892. depends on SLAB || SLUB
  893. help
  894. Provide fault-injection capability for kmalloc.
  895. config FAIL_PAGE_ALLOC
  896. bool "Fault-injection capabilitiy for alloc_pages()"
  897. depends on FAULT_INJECTION
  898. help
  899. Provide fault-injection capability for alloc_pages().
  900. config FAIL_MAKE_REQUEST
  901. bool "Fault-injection capability for disk IO"
  902. depends on FAULT_INJECTION && BLOCK
  903. help
  904. Provide fault-injection capability for disk IO.
  905. config FAIL_IO_TIMEOUT
  906. bool "Fault-injection capability for faking disk interrupts"
  907. depends on FAULT_INJECTION && BLOCK
  908. help
  909. Provide fault-injection capability on end IO handling. This
  910. will make the block layer "forget" an interrupt as configured,
  911. thus exercising the error handling.
  912. Only works with drivers that use the generic timeout handling,
  913. for others it wont do anything.
  914. config FAULT_INJECTION_DEBUG_FS
  915. bool "Debugfs entries for fault-injection capabilities"
  916. depends on FAULT_INJECTION && SYSFS && DEBUG_FS
  917. help
  918. Enable configuration of fault-injection capabilities via debugfs.
  919. config FAULT_INJECTION_STACKTRACE_FILTER
  920. bool "stacktrace filter for fault-injection capabilities"
  921. depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
  922. depends on !X86_64
  923. select STACKTRACE
  924. select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
  925. help
  926. Provide stacktrace filter for fault-injection capabilities
  927. config LATENCYTOP
  928. bool "Latency measuring infrastructure"
  929. depends on HAVE_LATENCYTOP_SUPPORT
  930. depends on DEBUG_KERNEL
  931. depends on STACKTRACE_SUPPORT
  932. depends on PROC_FS
  933. select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
  934. select KALLSYMS
  935. select KALLSYMS_ALL
  936. select STACKTRACE
  937. select SCHEDSTATS
  938. select SCHED_DEBUG
  939. help
  940. Enable this option if you want to use the LatencyTOP tool
  941. to find out which userspace is blocking on what kernel operations.
  942. config SYSCTL_SYSCALL_CHECK
  943. bool "Sysctl checks"
  944. depends on SYSCTL
  945. ---help---
  946. sys_sysctl uses binary paths that have been found challenging
  947. to properly maintain and use. This enables checks that help
  948. you to keep things correct.
  949. source mm/Kconfig.debug
  950. source kernel/trace/Kconfig
  951. config PROVIDE_OHCI1394_DMA_INIT
  952. bool "Remote debugging over FireWire early on boot"
  953. depends on PCI && X86
  954. help
  955. If you want to debug problems which hang or crash the kernel early
  956. on boot and the crashing machine has a FireWire port, you can use
  957. this feature to remotely access the memory of the crashed machine
  958. over FireWire. This employs remote DMA as part of the OHCI1394
  959. specification which is now the standard for FireWire controllers.
  960. With remote DMA, you can monitor the printk buffer remotely using
  961. firescope and access all memory below 4GB using fireproxy from gdb.
  962. Even controlling a kernel debugger is possible using remote DMA.
  963. Usage:
  964. If ohci1394_dma=early is used as boot parameter, it will initialize
  965. all OHCI1394 controllers which are found in the PCI config space.
  966. As all changes to the FireWire bus such as enabling and disabling
  967. devices cause a bus reset and thereby disable remote DMA for all
  968. devices, be sure to have the cable plugged and FireWire enabled on
  969. the debugging host before booting the debug target for debugging.
  970. This code (~1k) is freed after boot. By then, the firewire stack
  971. in charge of the OHCI-1394 controllers should be used instead.
  972. See Documentation/debugging-via-ohci1394.txt for more information.
  973. config FIREWIRE_OHCI_REMOTE_DMA
  974. bool "Remote debugging over FireWire with firewire-ohci"
  975. depends on FIREWIRE_OHCI
  976. help
  977. This option lets you use the FireWire bus for remote debugging
  978. with help of the firewire-ohci driver. It enables unfiltered
  979. remote DMA in firewire-ohci.
  980. See Documentation/debugging-via-ohci1394.txt for more information.
  981. If unsure, say N.
  982. config BUILD_DOCSRC
  983. bool "Build targets in Documentation/ tree"
  984. depends on HEADERS_CHECK
  985. help
  986. This option attempts to build objects from the source files in the
  987. kernel Documentation/ tree.
  988. Say N if you are unsure.
  989. config DYNAMIC_DEBUG
  990. bool "Enable dynamic printk() support"
  991. default n
  992. depends on PRINTK
  993. depends on DEBUG_FS
  994. help
  995. Compiles debug level messages into the kernel, which would not
  996. otherwise be available at runtime. These messages can then be
  997. enabled/disabled based on various levels of scope - per source file,
  998. function, module, format string, and line number. This mechanism
  999. implicitly enables all pr_debug() and dev_dbg() calls. The impact of
  1000. this compile option is a larger kernel text size of about 2%.
  1001. Usage:
  1002. Dynamic debugging is controlled via the 'dynamic_debug/control' file,
  1003. which is contained in the 'debugfs' filesystem. Thus, the debugfs
  1004. filesystem must first be mounted before making use of this feature.
  1005. We refer the control file as: <debugfs>/dynamic_debug/control. This
  1006. file contains a list of the debug statements that can be enabled. The
  1007. format for each line of the file is:
  1008. filename:lineno [module]function flags format
  1009. filename : source file of the debug statement
  1010. lineno : line number of the debug statement
  1011. module : module that contains the debug statement
  1012. function : function that contains the debug statement
  1013. flags : 'p' means the line is turned 'on' for printing
  1014. format : the format used for the debug statement
  1015. From a live system:
  1016. nullarbor:~ # cat <debugfs>/dynamic_debug/control
  1017. # filename:lineno [module]function flags format
  1018. fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
  1019. fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
  1020. fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
  1021. Example usage:
  1022. // enable the message at line 1603 of file svcsock.c
  1023. nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
  1024. <debugfs>/dynamic_debug/control
  1025. // enable all the messages in file svcsock.c
  1026. nullarbor:~ # echo -n 'file svcsock.c +p' >
  1027. <debugfs>/dynamic_debug/control
  1028. // enable all the messages in the NFS server module
  1029. nullarbor:~ # echo -n 'module nfsd +p' >
  1030. <debugfs>/dynamic_debug/control
  1031. // enable all 12 messages in the function svc_process()
  1032. nullarbor:~ # echo -n 'func svc_process +p' >
  1033. <debugfs>/dynamic_debug/control
  1034. // disable all 12 messages in the function svc_process()
  1035. nullarbor:~ # echo -n 'func svc_process -p' >
  1036. <debugfs>/dynamic_debug/control
  1037. See Documentation/dynamic-debug-howto.txt for additional information.
  1038. config DMA_API_DEBUG
  1039. bool "Enable debugging of DMA-API usage"
  1040. depends on HAVE_DMA_API_DEBUG
  1041. help
  1042. Enable this option to debug the use of the DMA API by device drivers.
  1043. With this option you will be able to detect common bugs in device
  1044. drivers like double-freeing of DMA mappings or freeing mappings that
  1045. were never allocated.
  1046. This option causes a performance degredation. Use only if you want
  1047. to debug device drivers. If unsure, say N.
  1048. config ATOMIC64_SELFTEST
  1049. bool "Perform an atomic64_t self-test at boot"
  1050. help
  1051. Enable this option to test the atomic64_t functions at boot.
  1052. If unsure, say N.
  1053. config ASYNC_RAID6_TEST
  1054. tristate "Self test for hardware accelerated raid6 recovery"
  1055. depends on ASYNC_RAID6_RECOV
  1056. select ASYNC_MEMCPY
  1057. ---help---
  1058. This is a one-shot self test that permutes through the
  1059. recovery of all the possible two disk failure scenarios for a
  1060. N-disk array. Recovery is performed with the asynchronous
  1061. raid6 recovery routines, and will optionally use an offload
  1062. engine if one is available.
  1063. If unsure, say N.
  1064. source "samples/Kconfig"
  1065. source "lib/Kconfig.kgdb"
  1066. source "lib/Kconfig.kmemcheck"
  1067. config TEST_KSTRTOX
  1068. tristate "Test kstrto*() family of functions at runtime"