Kconfig.debug 41 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 ENABLE_WARN_DEPRECATED
  11. bool "Enable __deprecated logic"
  12. default y
  13. help
  14. Enable the __deprecated logic in the kernel build.
  15. Disable this to suppress the "warning: 'foo' is deprecated
  16. (declared at kernel/power/somefile.c:1234)" messages.
  17. config ENABLE_MUST_CHECK
  18. bool "Enable __must_check logic"
  19. default y
  20. help
  21. Enable the __must_check logic in the kernel build. Disable this to
  22. suppress the "warning: ignoring return value of 'foo', declared with
  23. attribute warn_unused_result" messages.
  24. config FRAME_WARN
  25. int "Warn for stack frames larger than (needs gcc 4.4)"
  26. range 0 8192
  27. default 1024 if !64BIT
  28. default 2048 if 64BIT
  29. help
  30. Tell gcc to warn at build time for stack frames larger than this.
  31. Setting this too low will cause a lot of warnings.
  32. Setting it to 0 disables the warning.
  33. Requires gcc 4.4
  34. config MAGIC_SYSRQ
  35. bool "Magic SysRq key"
  36. depends on !UML
  37. help
  38. If you say Y here, you will have some control over the system even
  39. if the system crashes for example during kernel debugging (e.g., you
  40. will be able to flush the buffer cache to disk, reboot the system
  41. immediately or dump some status information). This is accomplished
  42. by pressing various keys while holding SysRq (Alt+PrintScreen). It
  43. also works on a serial console (on PC hardware at least), if you
  44. send a BREAK and then within 5 seconds a command keypress. The
  45. keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  46. unless you really know what this hack does.
  47. config STRIP_ASM_SYMS
  48. bool "Strip assembler-generated symbols during link"
  49. default n
  50. help
  51. Strip internal assembler-generated symbols during a link (symbols
  52. that look like '.Lxxx') so they don't pollute the output of
  53. get_wchan() and suchlike.
  54. config UNUSED_SYMBOLS
  55. bool "Enable unused/obsolete exported symbols"
  56. default y if X86
  57. help
  58. Unused but exported symbols make the kernel needlessly bigger. For
  59. that reason most of these unused exports will soon be removed. This
  60. option is provided temporarily to provide a transition period in case
  61. some external kernel module needs one of these symbols anyway. If you
  62. encounter such a case in your module, consider if you are actually
  63. using the right API. (rationale: since nobody in the kernel is using
  64. this in a module, there is a pretty good chance it's actually the
  65. wrong interface to use). If you really need the symbol, please send a
  66. mail to the linux kernel mailing list mentioning the symbol and why
  67. you really need it, and what the merge plan to the mainline kernel for
  68. your module is.
  69. config DEBUG_FS
  70. bool "Debug Filesystem"
  71. help
  72. debugfs is a virtual file system that kernel developers use to put
  73. debugging files into. Enable this option to be able to read and
  74. write to these files.
  75. For detailed documentation on the debugfs API, see
  76. Documentation/DocBook/filesystems.
  77. If unsure, say N.
  78. config HEADERS_CHECK
  79. bool "Run 'make headers_check' when building vmlinux"
  80. depends on !UML
  81. help
  82. This option will extract the user-visible kernel headers whenever
  83. building the kernel, and will run basic sanity checks on them to
  84. ensure that exported files do not attempt to include files which
  85. were not exported, etc.
  86. If you're making modifications to header files which are
  87. relevant for userspace, say 'Y', and check the headers
  88. exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  89. your build tree), to make sure they're suitable.
  90. config DEBUG_SECTION_MISMATCH
  91. bool "Enable full Section mismatch analysis"
  92. depends on UNDEFINED || (BLACKFIN)
  93. default y
  94. # This option is on purpose disabled for now.
  95. # It will be enabled when we are down to a reasonable number
  96. # of section mismatch warnings (< 10 for an allyesconfig build)
  97. help
  98. The section mismatch analysis checks if there are illegal
  99. references from one section to another section.
  100. Linux will during link or during runtime drop some sections
  101. and any use of code/data previously in these sections will
  102. most likely result in an oops.
  103. In the code functions and variables are annotated with
  104. __init, __devinit etc. (see full list in include/linux/init.h)
  105. which results in the code/data being placed in specific sections.
  106. The section mismatch analysis is always done after a full
  107. kernel build but enabling this option will in addition
  108. do the following:
  109. - Add the option -fno-inline-functions-called-once to gcc
  110. When inlining a function annotated __init in a non-init
  111. function we would lose the section information and thus
  112. the analysis would not catch the illegal reference.
  113. This option tells gcc to inline less but will also
  114. result in a larger kernel.
  115. - Run the section mismatch analysis for each module/built-in.o
  116. When we run the section mismatch analysis on vmlinux.o we
  117. lose valueble information about where the mismatch was
  118. introduced.
  119. Running the analysis for each module/built-in.o file
  120. will tell where the mismatch happens much closer to the
  121. source. The drawback is that we will report the same
  122. mismatch at least twice.
  123. - Enable verbose reporting from modpost to help solving
  124. the section mismatches reported.
  125. config DEBUG_KERNEL
  126. bool "Kernel debugging"
  127. help
  128. Say Y here if you are developing drivers or trying to debug and
  129. identify kernel problems.
  130. config DEBUG_SHIRQ
  131. bool "Debug shared IRQ handlers"
  132. depends on DEBUG_KERNEL && GENERIC_HARDIRQS
  133. help
  134. Enable this to generate a spurious interrupt as soon as a shared
  135. interrupt handler is registered, and just before one is deregistered.
  136. Drivers ought to be able to handle interrupts coming in at those
  137. points; some don't and need to be caught.
  138. config LOCKUP_DETECTOR
  139. bool "Detect Hard and Soft Lockups"
  140. depends on DEBUG_KERNEL && !S390
  141. help
  142. Say Y here to enable the kernel to act as a watchdog to detect
  143. hard and soft lockups.
  144. Softlockups are bugs that cause the kernel to loop in kernel
  145. mode for more than 60 seconds, without giving other tasks a
  146. chance to run. The current stack trace is displayed upon
  147. detection and the system will stay locked up.
  148. Hardlockups are bugs that cause the CPU to loop in kernel mode
  149. for more than 60 seconds, without letting other interrupts have a
  150. chance to run. The current stack trace is displayed upon detection
  151. and the system will stay locked up.
  152. The overhead should be minimal. A periodic hrtimer runs to
  153. generate interrupts and kick the watchdog task every 10-12 seconds.
  154. An NMI is generated every 60 seconds or so to check for hardlockups.
  155. config HARDLOCKUP_DETECTOR
  156. def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI
  157. config BOOTPARAM_SOFTLOCKUP_PANIC
  158. bool "Panic (Reboot) On Soft Lockups"
  159. depends on LOCKUP_DETECTOR
  160. help
  161. Say Y here to enable the kernel to panic on "soft lockups",
  162. which are bugs that cause the kernel to loop in kernel
  163. mode for more than 60 seconds, without giving other tasks a
  164. chance to run.
  165. The panic can be used in combination with panic_timeout,
  166. to cause the system to reboot automatically after a
  167. lockup has been detected. This feature is useful for
  168. high-availability systems that have uptime guarantees and
  169. where a lockup must be resolved ASAP.
  170. Say N if unsure.
  171. config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
  172. int
  173. depends on LOCKUP_DETECTOR
  174. range 0 1
  175. default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
  176. default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
  177. config DETECT_HUNG_TASK
  178. bool "Detect Hung Tasks"
  179. depends on DEBUG_KERNEL
  180. default DETECT_SOFTLOCKUP
  181. help
  182. Say Y here to enable the kernel to detect "hung tasks",
  183. which are bugs that cause the task to be stuck in
  184. uninterruptible "D" state indefinitiley.
  185. When a hung task is detected, the kernel will print the
  186. current stack trace (which you should report), but the
  187. task will stay in uninterruptible state. If lockdep is
  188. enabled then all held locks will also be reported. This
  189. feature has negligible overhead.
  190. config BOOTPARAM_HUNG_TASK_PANIC
  191. bool "Panic (Reboot) On Hung Tasks"
  192. depends on DETECT_HUNG_TASK
  193. help
  194. Say Y here to enable the kernel to panic on "hung tasks",
  195. which are bugs that cause the kernel to leave a task stuck
  196. in uninterruptible "D" state.
  197. The panic can be used in combination with panic_timeout,
  198. to cause the system to reboot automatically after a
  199. hung task has been detected. This feature is useful for
  200. high-availability systems that have uptime guarantees and
  201. where a hung tasks must be resolved ASAP.
  202. Say N if unsure.
  203. config BOOTPARAM_HUNG_TASK_PANIC_VALUE
  204. int
  205. depends on DETECT_HUNG_TASK
  206. range 0 1
  207. default 0 if !BOOTPARAM_HUNG_TASK_PANIC
  208. default 1 if BOOTPARAM_HUNG_TASK_PANIC
  209. config SCHED_DEBUG
  210. bool "Collect scheduler debugging info"
  211. depends on DEBUG_KERNEL && PROC_FS
  212. default y
  213. help
  214. If you say Y here, the /proc/sched_debug file will be provided
  215. that can help debug the scheduler. The runtime overhead of this
  216. option is minimal.
  217. config SCHEDSTATS
  218. bool "Collect scheduler statistics"
  219. depends on DEBUG_KERNEL && PROC_FS
  220. help
  221. If you say Y here, additional code will be inserted into the
  222. scheduler and related routines to collect statistics about
  223. scheduler behavior and provide them in /proc/schedstat. These
  224. stats may be useful for both tuning and debugging the scheduler
  225. If you aren't debugging the scheduler or trying to tune a specific
  226. application, you can say N to avoid the very slight overhead
  227. this adds.
  228. config TIMER_STATS
  229. bool "Collect kernel timers statistics"
  230. depends on DEBUG_KERNEL && PROC_FS
  231. help
  232. If you say Y here, additional code will be inserted into the
  233. timer routines to collect statistics about kernel timers being
  234. reprogrammed. The statistics can be read from /proc/timer_stats.
  235. The statistics collection is started by writing 1 to /proc/timer_stats,
  236. writing 0 stops it. This feature is useful to collect information
  237. about timer usage patterns in kernel and userspace. This feature
  238. is lightweight if enabled in the kernel config but not activated
  239. (it defaults to deactivated on bootup and will only be activated
  240. if some application like powertop activates it explicitly).
  241. config DEBUG_OBJECTS
  242. bool "Debug object operations"
  243. depends on DEBUG_KERNEL
  244. help
  245. If you say Y here, additional code will be inserted into the
  246. kernel to track the life time of various objects and validate
  247. the operations on those objects.
  248. config DEBUG_OBJECTS_SELFTEST
  249. bool "Debug objects selftest"
  250. depends on DEBUG_OBJECTS
  251. help
  252. This enables the selftest of the object debug code.
  253. config DEBUG_OBJECTS_FREE
  254. bool "Debug objects in freed memory"
  255. depends on DEBUG_OBJECTS
  256. help
  257. This enables checks whether a k/v free operation frees an area
  258. which contains an object which has not been deactivated
  259. properly. This can make kmalloc/kfree-intensive workloads
  260. much slower.
  261. config DEBUG_OBJECTS_TIMERS
  262. bool "Debug timer objects"
  263. depends on DEBUG_OBJECTS
  264. help
  265. If you say Y here, additional code will be inserted into the
  266. timer routines to track the life time of timer objects and
  267. validate the timer operations.
  268. config DEBUG_OBJECTS_WORK
  269. bool "Debug work objects"
  270. depends on DEBUG_OBJECTS
  271. help
  272. If you say Y here, additional code will be inserted into the
  273. work queue routines to track the life time of work objects and
  274. validate the work operations.
  275. config DEBUG_OBJECTS_RCU_HEAD
  276. bool "Debug RCU callbacks objects"
  277. depends on DEBUG_OBJECTS && PREEMPT
  278. help
  279. Enable this to turn on debugging of RCU list heads (call_rcu() usage).
  280. config DEBUG_OBJECTS_ENABLE_DEFAULT
  281. int "debug_objects bootup default value (0-1)"
  282. range 0 1
  283. default "1"
  284. depends on DEBUG_OBJECTS
  285. help
  286. Debug objects boot parameter default value
  287. config DEBUG_SLAB
  288. bool "Debug slab memory allocations"
  289. depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
  290. help
  291. Say Y here to have the kernel do limited verification on memory
  292. allocation as well as poisoning memory on free to catch use of freed
  293. memory. This can make kmalloc/kfree-intensive workloads much slower.
  294. config DEBUG_SLAB_LEAK
  295. bool "Memory leak debugging"
  296. depends on DEBUG_SLAB
  297. config SLUB_DEBUG_ON
  298. bool "SLUB debugging on by default"
  299. depends on SLUB && SLUB_DEBUG && !KMEMCHECK
  300. default n
  301. help
  302. Boot with debugging on by default. SLUB boots by default with
  303. the runtime debug capabilities switched off. Enabling this is
  304. equivalent to specifying the "slub_debug" parameter on boot.
  305. There is no support for more fine grained debug control like
  306. possible with slub_debug=xxx. SLUB debugging may be switched
  307. off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
  308. "slub_debug=-".
  309. config SLUB_STATS
  310. default n
  311. bool "Enable SLUB performance statistics"
  312. depends on SLUB && SLUB_DEBUG && SYSFS
  313. help
  314. SLUB statistics are useful to debug SLUBs allocation behavior in
  315. order find ways to optimize the allocator. This should never be
  316. enabled for production use since keeping statistics slows down
  317. the allocator by a few percentage points. The slabinfo command
  318. supports the determination of the most active slabs to figure
  319. out which slabs are relevant to a particular load.
  320. Try running: slabinfo -DA
  321. config DEBUG_KMEMLEAK
  322. bool "Kernel memory leak detector"
  323. depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
  324. (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE)
  325. select DEBUG_FS if SYSFS
  326. select STACKTRACE if STACKTRACE_SUPPORT
  327. select KALLSYMS
  328. select CRC32
  329. help
  330. Say Y here if you want to enable the memory leak
  331. detector. The memory allocation/freeing is traced in a way
  332. similar to the Boehm's conservative garbage collector, the
  333. difference being that the orphan objects are not freed but
  334. only shown in /sys/kernel/debug/kmemleak. Enabling this
  335. feature will introduce an overhead to memory
  336. allocations. See Documentation/kmemleak.txt for more
  337. details.
  338. Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
  339. of finding leaks due to the slab objects poisoning.
  340. In order to access the kmemleak file, debugfs needs to be
  341. mounted (usually at /sys/kernel/debug).
  342. config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
  343. int "Maximum kmemleak early log entries"
  344. depends on DEBUG_KMEMLEAK
  345. range 200 40000
  346. default 400
  347. help
  348. Kmemleak must track all the memory allocations to avoid
  349. reporting false positives. Since memory may be allocated or
  350. freed before kmemleak is initialised, an early log buffer is
  351. used to store these actions. If kmemleak reports "early log
  352. buffer exceeded", please increase this value.
  353. config DEBUG_KMEMLEAK_TEST
  354. tristate "Simple test for the kernel memory leak detector"
  355. depends on DEBUG_KMEMLEAK
  356. help
  357. Say Y or M here to build a test for the kernel memory leak
  358. detector. This option enables a module that explicitly leaks
  359. memory.
  360. If unsure, say N.
  361. config DEBUG_KMEMLEAK_DEFAULT_OFF
  362. bool "Default kmemleak to off"
  363. depends on DEBUG_KMEMLEAK
  364. help
  365. Say Y here to disable kmemleak by default. It can then be enabled
  366. on the command line via kmemleak=on.
  367. config DEBUG_PREEMPT
  368. bool "Debug preemptible kernel"
  369. depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
  370. default y
  371. help
  372. If you say Y here then the kernel will use a debug variant of the
  373. commonly used smp_processor_id() function and will print warnings
  374. if kernel code uses it in a preemption-unsafe way. Also, the kernel
  375. will detect preemption count underflows.
  376. config DEBUG_RT_MUTEXES
  377. bool "RT Mutex debugging, deadlock detection"
  378. depends on DEBUG_KERNEL && RT_MUTEXES
  379. help
  380. This allows rt mutex semantics violations and rt mutex related
  381. deadlocks (lockups) to be detected and reported automatically.
  382. config DEBUG_PI_LIST
  383. bool
  384. default y
  385. depends on DEBUG_RT_MUTEXES
  386. config RT_MUTEX_TESTER
  387. bool "Built-in scriptable tester for rt-mutexes"
  388. depends on DEBUG_KERNEL && RT_MUTEXES
  389. help
  390. This option enables a rt-mutex tester.
  391. config DEBUG_SPINLOCK
  392. bool "Spinlock and rw-lock debugging: basic checks"
  393. depends on DEBUG_KERNEL
  394. help
  395. Say Y here and build SMP to catch missing spinlock initialization
  396. and certain other kinds of spinlock errors commonly made. This is
  397. best used in conjunction with the NMI watchdog so that spinlock
  398. deadlocks are also debuggable.
  399. config DEBUG_MUTEXES
  400. bool "Mutex debugging: basic checks"
  401. depends on DEBUG_KERNEL
  402. help
  403. This feature allows mutex semantics violations to be detected and
  404. reported.
  405. config BKL
  406. bool "Big Kernel Lock" if (SMP || PREEMPT)
  407. default y
  408. help
  409. This is the traditional lock that is used in old code instead
  410. of proper locking. All drivers that use the BKL should depend
  411. on this symbol.
  412. Say Y here unless you are working on removing the BKL.
  413. config DEBUG_LOCK_ALLOC
  414. bool "Lock debugging: detect incorrect freeing of live locks"
  415. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  416. select DEBUG_SPINLOCK
  417. select DEBUG_MUTEXES
  418. select LOCKDEP
  419. help
  420. This feature will check whether any held lock (spinlock, rwlock,
  421. mutex or rwsem) is incorrectly freed by the kernel, via any of the
  422. memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
  423. vfree(), etc.), whether a live lock is incorrectly reinitialized via
  424. spin_lock_init()/mutex_init()/etc., or whether there is any lock
  425. held during task exit.
  426. config PROVE_LOCKING
  427. bool "Lock debugging: prove locking correctness"
  428. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  429. select LOCKDEP
  430. select DEBUG_SPINLOCK
  431. select DEBUG_MUTEXES
  432. select DEBUG_LOCK_ALLOC
  433. select TRACE_IRQFLAGS
  434. default n
  435. help
  436. This feature enables the kernel to prove that all locking
  437. that occurs in the kernel runtime is mathematically
  438. correct: that under no circumstance could an arbitrary (and
  439. not yet triggered) combination of observed locking
  440. sequences (on an arbitrary number of CPUs, running an
  441. arbitrary number of tasks and interrupt contexts) cause a
  442. deadlock.
  443. In short, this feature enables the kernel to report locking
  444. related deadlocks before they actually occur.
  445. The proof does not depend on how hard and complex a
  446. deadlock scenario would be to trigger: how many
  447. participant CPUs, tasks and irq-contexts would be needed
  448. for it to trigger. The proof also does not depend on
  449. timing: if a race and a resulting deadlock is possible
  450. theoretically (no matter how unlikely the race scenario
  451. is), it will be proven so and will immediately be
  452. reported by the kernel (once the event is observed that
  453. makes the deadlock theoretically possible).
  454. If a deadlock is impossible (i.e. the locking rules, as
  455. observed by the kernel, are mathematically correct), the
  456. kernel reports nothing.
  457. NOTE: this feature can also be enabled for rwlocks, mutexes
  458. and rwsems - in which case all dependencies between these
  459. different locking variants are observed and mapped too, and
  460. the proof of observed correctness is also maintained for an
  461. arbitrary combination of these separate locking variants.
  462. For more details, see Documentation/lockdep-design.txt.
  463. config PROVE_RCU
  464. bool "RCU debugging: prove RCU correctness"
  465. depends on PROVE_LOCKING
  466. default n
  467. help
  468. This feature enables lockdep extensions that check for correct
  469. use of RCU APIs. This is currently under development. Say Y
  470. if you want to debug RCU usage or help work on the PROVE_RCU
  471. feature.
  472. Say N if you are unsure.
  473. config PROVE_RCU_REPEATEDLY
  474. bool "RCU debugging: don't disable PROVE_RCU on first splat"
  475. depends on PROVE_RCU
  476. default n
  477. help
  478. By itself, PROVE_RCU will disable checking upon issuing the
  479. first warning (or "splat"). This feature prevents such
  480. disabling, allowing multiple RCU-lockdep warnings to be printed
  481. on a single reboot.
  482. Say Y to allow multiple RCU-lockdep warnings per boot.
  483. Say N if you are unsure.
  484. config SPARSE_RCU_POINTER
  485. bool "RCU debugging: sparse-based checks for pointer usage"
  486. default n
  487. help
  488. This feature enables the __rcu sparse annotation for
  489. RCU-protected pointers. This annotation will cause sparse
  490. to flag any non-RCU used of annotated pointers. This can be
  491. helpful when debugging RCU usage. Please note that this feature
  492. is not intended to enforce code cleanliness; it is instead merely
  493. a debugging aid.
  494. Say Y to make sparse flag questionable use of RCU-protected pointers
  495. Say N if you are unsure.
  496. config LOCKDEP
  497. bool
  498. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  499. select STACKTRACE
  500. select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
  501. select KALLSYMS
  502. select KALLSYMS_ALL
  503. config LOCK_STAT
  504. bool "Lock usage statistics"
  505. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  506. select LOCKDEP
  507. select DEBUG_SPINLOCK
  508. select DEBUG_MUTEXES
  509. select DEBUG_LOCK_ALLOC
  510. default n
  511. help
  512. This feature enables tracking lock contention points
  513. For more details, see Documentation/lockstat.txt
  514. This also enables lock events required by "perf lock",
  515. subcommand of perf.
  516. If you want to use "perf lock", you also need to turn on
  517. CONFIG_EVENT_TRACING.
  518. CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
  519. (CONFIG_LOCKDEP defines "acquire" and "release" events.)
  520. config DEBUG_LOCKDEP
  521. bool "Lock dependency engine debugging"
  522. depends on DEBUG_KERNEL && LOCKDEP
  523. help
  524. If you say Y here, the lock dependency engine will do
  525. additional runtime checks to debug itself, at the price
  526. of more runtime overhead.
  527. config TRACE_IRQFLAGS
  528. bool
  529. help
  530. Enables hooks to interrupt enabling and disabling for
  531. either tracing or lock debugging.
  532. config DEBUG_SPINLOCK_SLEEP
  533. bool "Spinlock debugging: sleep-inside-spinlock checking"
  534. depends on DEBUG_KERNEL
  535. help
  536. If you say Y here, various routines which may sleep will become very
  537. noisy if they are called with a spinlock held.
  538. config DEBUG_LOCKING_API_SELFTESTS
  539. bool "Locking API boot-time self-tests"
  540. depends on DEBUG_KERNEL
  541. help
  542. Say Y here if you want the kernel to run a short self-test during
  543. bootup. The self-test checks whether common types of locking bugs
  544. are detected by debugging mechanisms or not. (if you disable
  545. lock debugging then those bugs wont be detected of course.)
  546. The following locking APIs are covered: spinlocks, rwlocks,
  547. mutexes and rwsems.
  548. config STACKTRACE
  549. bool
  550. depends on STACKTRACE_SUPPORT
  551. config DEBUG_KOBJECT
  552. bool "kobject debugging"
  553. depends on DEBUG_KERNEL
  554. help
  555. If you say Y here, some extra kobject debugging messages will be sent
  556. to the syslog.
  557. config DEBUG_HIGHMEM
  558. bool "Highmem debugging"
  559. depends on DEBUG_KERNEL && HIGHMEM
  560. help
  561. This options enables addition error checking for high memory systems.
  562. Disable for production systems.
  563. config DEBUG_BUGVERBOSE
  564. bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
  565. depends on BUG
  566. depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
  567. FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
  568. default y
  569. help
  570. Say Y here to make BUG() panics output the file name and line number
  571. of the BUG call as well as the EIP and oops trace. This aids
  572. debugging but costs about 70-100K of memory.
  573. config DEBUG_INFO
  574. bool "Compile the kernel with debug info"
  575. depends on DEBUG_KERNEL
  576. help
  577. If you say Y here the resulting kernel image will include
  578. debugging info resulting in a larger kernel image.
  579. This adds debug symbols to the kernel and modules (gcc -g), and
  580. is needed if you intend to use kernel crashdump or binary object
  581. tools like crash, kgdb, LKCD, gdb, etc on the kernel.
  582. Say Y here only if you plan to debug the kernel.
  583. If unsure, say N.
  584. config DEBUG_INFO_REDUCED
  585. bool "Reduce debugging information"
  586. depends on DEBUG_INFO
  587. help
  588. If you say Y here gcc is instructed to generate less debugging
  589. information for structure types. This means that tools that
  590. need full debugging information (like kgdb or systemtap) won't
  591. be happy. But if you merely need debugging information to
  592. resolve line numbers there is no loss. Advantage is that
  593. build directory object sizes shrink dramatically over a full
  594. DEBUG_INFO build and compile times are reduced too.
  595. Only works with newer gcc versions.
  596. config DEBUG_VM
  597. bool "Debug VM"
  598. depends on DEBUG_KERNEL
  599. help
  600. Enable this to turn on extended checks in the virtual-memory system
  601. that may impact performance.
  602. If unsure, say N.
  603. config DEBUG_VIRTUAL
  604. bool "Debug VM translations"
  605. depends on DEBUG_KERNEL && X86
  606. help
  607. Enable some costly sanity checks in virtual to page code. This can
  608. catch mistakes with virt_to_page() and friends.
  609. If unsure, say N.
  610. config DEBUG_NOMMU_REGIONS
  611. bool "Debug the global anon/private NOMMU mapping region tree"
  612. depends on DEBUG_KERNEL && !MMU
  613. help
  614. This option causes the global tree of anonymous and private mapping
  615. regions to be regularly checked for invalid topology.
  616. config DEBUG_WRITECOUNT
  617. bool "Debug filesystem writers count"
  618. depends on DEBUG_KERNEL
  619. help
  620. Enable this to catch wrong use of the writers count in struct
  621. vfsmount. This will increase the size of each file struct by
  622. 32 bits.
  623. If unsure, say N.
  624. config DEBUG_MEMORY_INIT
  625. bool "Debug memory initialisation" if EMBEDDED
  626. default !EMBEDDED
  627. help
  628. Enable this for additional checks during memory initialisation.
  629. The sanity checks verify aspects of the VM such as the memory model
  630. and other information provided by the architecture. Verbose
  631. information will be printed at KERN_DEBUG loglevel depending
  632. on the mminit_loglevel= command-line option.
  633. If unsure, say Y
  634. config DEBUG_LIST
  635. bool "Debug linked list manipulation"
  636. depends on DEBUG_KERNEL
  637. help
  638. Enable this to turn on extended checks in the linked-list
  639. walking routines.
  640. If unsure, say N.
  641. config DEBUG_SG
  642. bool "Debug SG table operations"
  643. depends on DEBUG_KERNEL
  644. help
  645. Enable this to turn on checks on scatter-gather tables. This can
  646. help find problems with drivers that do not properly initialize
  647. their sg tables.
  648. If unsure, say N.
  649. config DEBUG_NOTIFIERS
  650. bool "Debug notifier call chains"
  651. depends on DEBUG_KERNEL
  652. help
  653. Enable this to turn on sanity checking for notifier call chains.
  654. This is most useful for kernel developers to make sure that
  655. modules properly unregister themselves from notifier chains.
  656. This is a relatively cheap check but if you care about maximum
  657. performance, say N.
  658. config DEBUG_CREDENTIALS
  659. bool "Debug credential management"
  660. depends on DEBUG_KERNEL
  661. help
  662. Enable this to turn on some debug checking for credential
  663. management. The additional code keeps track of the number of
  664. pointers from task_structs to any given cred struct, and checks to
  665. see that this number never exceeds the usage count of the cred
  666. struct.
  667. Furthermore, if SELinux is enabled, this also checks that the
  668. security pointer in the cred struct is never seen to be invalid.
  669. If unsure, say N.
  670. #
  671. # Select this config option from the architecture Kconfig, if it
  672. # it is preferred to always offer frame pointers as a config
  673. # option on the architecture (regardless of KERNEL_DEBUG):
  674. #
  675. config ARCH_WANT_FRAME_POINTERS
  676. bool
  677. help
  678. config FRAME_POINTER
  679. bool "Compile the kernel with frame pointers"
  680. depends on DEBUG_KERNEL && \
  681. (CRIS || M68K || M68KNOMMU || FRV || UML || \
  682. AVR32 || SUPERH || BLACKFIN || MN10300) || \
  683. ARCH_WANT_FRAME_POINTERS
  684. default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
  685. help
  686. If you say Y here the resulting kernel image will be slightly
  687. larger and slower, but it gives very useful debugging information
  688. in case of kernel bugs. (precise oopses/stacktraces/warnings)
  689. config BOOT_PRINTK_DELAY
  690. bool "Delay each boot printk message by N milliseconds"
  691. depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
  692. help
  693. This build option allows you to read kernel boot messages
  694. by inserting a short delay after each one. The delay is
  695. specified in milliseconds on the kernel command line,
  696. using "boot_delay=N".
  697. It is likely that you would also need to use "lpj=M" to preset
  698. the "loops per jiffie" value.
  699. See a previous boot log for the "lpj" value to use for your
  700. system, and then set "lpj=M" before setting "boot_delay=N".
  701. NOTE: Using this option may adversely affect SMP systems.
  702. I.e., processors other than the first one may not boot up.
  703. BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
  704. what it believes to be lockup conditions.
  705. config RCU_TORTURE_TEST
  706. tristate "torture tests for RCU"
  707. depends on DEBUG_KERNEL
  708. default n
  709. help
  710. This option provides a kernel module that runs torture tests
  711. on the RCU infrastructure. The kernel module may be built
  712. after the fact on the running kernel to be tested, if desired.
  713. Say Y here if you want RCU torture tests to be built into
  714. the kernel.
  715. Say M if you want the RCU torture tests to build as a module.
  716. Say N if you are unsure.
  717. config RCU_TORTURE_TEST_RUNNABLE
  718. bool "torture tests for RCU runnable by default"
  719. depends on RCU_TORTURE_TEST = y
  720. default n
  721. help
  722. This option provides a way to build the RCU torture tests
  723. directly into the kernel without them starting up at boot
  724. time. You can use /proc/sys/kernel/rcutorture_runnable
  725. to manually override this setting. This /proc file is
  726. available only when the RCU torture tests have been built
  727. into the kernel.
  728. Say Y here if you want the RCU torture tests to start during
  729. boot (you probably don't).
  730. Say N here if you want the RCU torture tests to start only
  731. after being manually enabled via /proc.
  732. config RCU_CPU_STALL_DETECTOR
  733. bool "Check for stalled CPUs delaying RCU grace periods"
  734. depends on TREE_RCU || TREE_PREEMPT_RCU
  735. default y
  736. help
  737. This option causes RCU to printk information on which
  738. CPUs are delaying the current grace period, but only when
  739. the grace period extends for excessive time periods.
  740. Say N if you want to disable such checks.
  741. Say Y if you are unsure.
  742. config RCU_CPU_STALL_TIMEOUT
  743. int "RCU CPU stall timeout in seconds"
  744. depends on RCU_CPU_STALL_DETECTOR
  745. range 3 300
  746. default 60
  747. help
  748. If a given RCU grace period extends more than the specified
  749. number of seconds, a CPU stall warning is printed. If the
  750. RCU grace period persists, additional CPU stall warnings are
  751. printed at more widely spaced intervals.
  752. config RCU_CPU_STALL_DETECTOR_RUNNABLE
  753. bool "RCU CPU stall checking starts automatically at boot"
  754. depends on RCU_CPU_STALL_DETECTOR
  755. default y
  756. help
  757. If set, start checking for RCU CPU stalls immediately on
  758. boot. Otherwise, RCU CPU stall checking must be manually
  759. enabled.
  760. Say Y if you are unsure.
  761. Say N if you wish to suppress RCU CPU stall checking during boot.
  762. config RCU_CPU_STALL_VERBOSE
  763. bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
  764. depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
  765. default y
  766. help
  767. This option causes RCU to printk detailed per-task information
  768. for any tasks that are stalling the current RCU grace period.
  769. Say N if you are unsure.
  770. Say Y if you want to enable such checks.
  771. config KPROBES_SANITY_TEST
  772. bool "Kprobes sanity tests"
  773. depends on DEBUG_KERNEL
  774. depends on KPROBES
  775. default n
  776. help
  777. This option provides for testing basic kprobes functionality on
  778. boot. A sample kprobe, jprobe and kretprobe are inserted and
  779. verified for functionality.
  780. Say N if you are unsure.
  781. config BACKTRACE_SELF_TEST
  782. tristate "Self test for the backtrace code"
  783. depends on DEBUG_KERNEL
  784. default n
  785. help
  786. This option provides a kernel module that can be used to test
  787. the kernel stack backtrace code. This option is not useful
  788. for distributions or general kernels, but only for kernel
  789. developers working on architecture code.
  790. Note that if you want to also test saved backtraces, you will
  791. have to enable STACKTRACE as well.
  792. Say N if you are unsure.
  793. config DEBUG_BLOCK_EXT_DEVT
  794. bool "Force extended block device numbers and spread them"
  795. depends on DEBUG_KERNEL
  796. depends on BLOCK
  797. default n
  798. help
  799. BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
  800. SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
  801. YOU ARE DOING. Distros, please enable this and fix whatever
  802. is broken.
  803. Conventionally, block device numbers are allocated from
  804. predetermined contiguous area. However, extended block area
  805. may introduce non-contiguous block device numbers. This
  806. option forces most block device numbers to be allocated from
  807. the extended space and spreads them to discover kernel or
  808. userland code paths which assume predetermined contiguous
  809. device number allocation.
  810. Note that turning on this debug option shuffles all the
  811. device numbers for all IDE and SCSI devices including libata
  812. ones, so root partition specified using device number
  813. directly (via rdev or root=MAJ:MIN) won't work anymore.
  814. Textual device names (root=/dev/sdXn) will continue to work.
  815. Say N if you are unsure.
  816. config DEBUG_FORCE_WEAK_PER_CPU
  817. bool "Force weak per-cpu definitions"
  818. depends on DEBUG_KERNEL
  819. help
  820. s390 and alpha require percpu variables in modules to be
  821. defined weak to work around addressing range issue which
  822. puts the following two restrictions on percpu variable
  823. definitions.
  824. 1. percpu symbols must be unique whether static or not
  825. 2. percpu variables can't be defined inside a function
  826. To ensure that generic code follows the above rules, this
  827. option forces all percpu variables to be defined as weak.
  828. config LKDTM
  829. tristate "Linux Kernel Dump Test Tool Module"
  830. depends on DEBUG_FS
  831. depends on BLOCK
  832. default n
  833. help
  834. This module enables testing of the different dumping mechanisms by
  835. inducing system failures at predefined crash points.
  836. If you don't need it: say N
  837. Choose M here to compile this code as a module. The module will be
  838. called lkdtm.
  839. Documentation on how to use the module can be found in
  840. Documentation/fault-injection/provoke-crashes.txt
  841. config CPU_NOTIFIER_ERROR_INJECT
  842. tristate "CPU notifier error injection module"
  843. depends on HOTPLUG_CPU && DEBUG_KERNEL
  844. help
  845. This option provides a kernel module that can be used to test
  846. the error handling of the cpu notifiers
  847. To compile this code as a module, choose M here: the module will
  848. be called cpu-notifier-error-inject.
  849. If unsure, say N.
  850. config FAULT_INJECTION
  851. bool "Fault-injection framework"
  852. depends on DEBUG_KERNEL
  853. help
  854. Provide fault-injection framework.
  855. For more details, see Documentation/fault-injection/.
  856. config FAILSLAB
  857. bool "Fault-injection capability for kmalloc"
  858. depends on FAULT_INJECTION
  859. depends on SLAB || SLUB
  860. help
  861. Provide fault-injection capability for kmalloc.
  862. config FAIL_PAGE_ALLOC
  863. bool "Fault-injection capabilitiy for alloc_pages()"
  864. depends on FAULT_INJECTION
  865. help
  866. Provide fault-injection capability for alloc_pages().
  867. config FAIL_MAKE_REQUEST
  868. bool "Fault-injection capability for disk IO"
  869. depends on FAULT_INJECTION && BLOCK
  870. help
  871. Provide fault-injection capability for disk IO.
  872. config FAIL_IO_TIMEOUT
  873. bool "Fault-injection capability for faking disk interrupts"
  874. depends on FAULT_INJECTION && BLOCK
  875. help
  876. Provide fault-injection capability on end IO handling. This
  877. will make the block layer "forget" an interrupt as configured,
  878. thus exercising the error handling.
  879. Only works with drivers that use the generic timeout handling,
  880. for others it wont do anything.
  881. config FAULT_INJECTION_DEBUG_FS
  882. bool "Debugfs entries for fault-injection capabilities"
  883. depends on FAULT_INJECTION && SYSFS && DEBUG_FS
  884. help
  885. Enable configuration of fault-injection capabilities via debugfs.
  886. config FAULT_INJECTION_STACKTRACE_FILTER
  887. bool "stacktrace filter for fault-injection capabilities"
  888. depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
  889. depends on !X86_64
  890. select STACKTRACE
  891. select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
  892. help
  893. Provide stacktrace filter for fault-injection capabilities
  894. config LATENCYTOP
  895. bool "Latency measuring infrastructure"
  896. depends on HAVE_LATENCYTOP_SUPPORT
  897. depends on DEBUG_KERNEL
  898. depends on STACKTRACE_SUPPORT
  899. depends on PROC_FS
  900. select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
  901. select KALLSYMS
  902. select KALLSYMS_ALL
  903. select STACKTRACE
  904. select SCHEDSTATS
  905. select SCHED_DEBUG
  906. help
  907. Enable this option if you want to use the LatencyTOP tool
  908. to find out which userspace is blocking on what kernel operations.
  909. config SYSCTL_SYSCALL_CHECK
  910. bool "Sysctl checks"
  911. depends on SYSCTL
  912. ---help---
  913. sys_sysctl uses binary paths that have been found challenging
  914. to properly maintain and use. This enables checks that help
  915. you to keep things correct.
  916. source mm/Kconfig.debug
  917. source kernel/trace/Kconfig
  918. config PROVIDE_OHCI1394_DMA_INIT
  919. bool "Remote debugging over FireWire early on boot"
  920. depends on PCI && X86
  921. help
  922. If you want to debug problems which hang or crash the kernel early
  923. on boot and the crashing machine has a FireWire port, you can use
  924. this feature to remotely access the memory of the crashed machine
  925. over FireWire. This employs remote DMA as part of the OHCI1394
  926. specification which is now the standard for FireWire controllers.
  927. With remote DMA, you can monitor the printk buffer remotely using
  928. firescope and access all memory below 4GB using fireproxy from gdb.
  929. Even controlling a kernel debugger is possible using remote DMA.
  930. Usage:
  931. If ohci1394_dma=early is used as boot parameter, it will initialize
  932. all OHCI1394 controllers which are found in the PCI config space.
  933. As all changes to the FireWire bus such as enabling and disabling
  934. devices cause a bus reset and thereby disable remote DMA for all
  935. devices, be sure to have the cable plugged and FireWire enabled on
  936. the debugging host before booting the debug target for debugging.
  937. This code (~1k) is freed after boot. By then, the firewire stack
  938. in charge of the OHCI-1394 controllers should be used instead.
  939. See Documentation/debugging-via-ohci1394.txt for more information.
  940. config FIREWIRE_OHCI_REMOTE_DMA
  941. bool "Remote debugging over FireWire with firewire-ohci"
  942. depends on FIREWIRE_OHCI
  943. help
  944. This option lets you use the FireWire bus for remote debugging
  945. with help of the firewire-ohci driver. It enables unfiltered
  946. remote DMA in firewire-ohci.
  947. See Documentation/debugging-via-ohci1394.txt for more information.
  948. If unsure, say N.
  949. config BUILD_DOCSRC
  950. bool "Build targets in Documentation/ tree"
  951. depends on HEADERS_CHECK
  952. help
  953. This option attempts to build objects from the source files in the
  954. kernel Documentation/ tree.
  955. Say N if you are unsure.
  956. config DYNAMIC_DEBUG
  957. bool "Enable dynamic printk() support"
  958. default n
  959. depends on PRINTK
  960. depends on DEBUG_FS
  961. help
  962. Compiles debug level messages into the kernel, which would not
  963. otherwise be available at runtime. These messages can then be
  964. enabled/disabled based on various levels of scope - per source file,
  965. function, module, format string, and line number. This mechanism
  966. implicitly enables all pr_debug() and dev_dbg() calls. The impact of
  967. this compile option is a larger kernel text size of about 2%.
  968. Usage:
  969. Dynamic debugging is controlled via the 'dynamic_debug/control' file,
  970. which is contained in the 'debugfs' filesystem. Thus, the debugfs
  971. filesystem must first be mounted before making use of this feature.
  972. We refer the control file as: <debugfs>/dynamic_debug/control. This
  973. file contains a list of the debug statements that can be enabled. The
  974. format for each line of the file is:
  975. filename:lineno [module]function flags format
  976. filename : source file of the debug statement
  977. lineno : line number of the debug statement
  978. module : module that contains the debug statement
  979. function : function that contains the debug statement
  980. flags : 'p' means the line is turned 'on' for printing
  981. format : the format used for the debug statement
  982. From a live system:
  983. nullarbor:~ # cat <debugfs>/dynamic_debug/control
  984. # filename:lineno [module]function flags format
  985. fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
  986. fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
  987. fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
  988. Example usage:
  989. // enable the message at line 1603 of file svcsock.c
  990. nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
  991. <debugfs>/dynamic_debug/control
  992. // enable all the messages in file svcsock.c
  993. nullarbor:~ # echo -n 'file svcsock.c +p' >
  994. <debugfs>/dynamic_debug/control
  995. // enable all the messages in the NFS server module
  996. nullarbor:~ # echo -n 'module nfsd +p' >
  997. <debugfs>/dynamic_debug/control
  998. // enable all 12 messages in the function svc_process()
  999. nullarbor:~ # echo -n 'func svc_process +p' >
  1000. <debugfs>/dynamic_debug/control
  1001. // disable all 12 messages in the function svc_process()
  1002. nullarbor:~ # echo -n 'func svc_process -p' >
  1003. <debugfs>/dynamic_debug/control
  1004. See Documentation/dynamic-debug-howto.txt for additional information.
  1005. config DMA_API_DEBUG
  1006. bool "Enable debugging of DMA-API usage"
  1007. depends on HAVE_DMA_API_DEBUG
  1008. help
  1009. Enable this option to debug the use of the DMA API by device drivers.
  1010. With this option you will be able to detect common bugs in device
  1011. drivers like double-freeing of DMA mappings or freeing mappings that
  1012. were never allocated.
  1013. This option causes a performance degredation. Use only if you want
  1014. to debug device drivers. If unsure, say N.
  1015. config ATOMIC64_SELFTEST
  1016. bool "Perform an atomic64_t self-test at boot"
  1017. help
  1018. Enable this option to test the atomic64_t functions at boot.
  1019. If unsure, say N.
  1020. source "samples/Kconfig"
  1021. source "lib/Kconfig.kgdb"
  1022. source "lib/Kconfig.kmemcheck"