Kconfig.debug 33 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 UNUSED_SYMBOLS
  48. bool "Enable unused/obsolete exported symbols"
  49. default y if X86
  50. help
  51. Unused but exported symbols make the kernel needlessly bigger. For
  52. that reason most of these unused exports will soon be removed. This
  53. option is provided temporarily to provide a transition period in case
  54. some external kernel module needs one of these symbols anyway. If you
  55. encounter such a case in your module, consider if you are actually
  56. using the right API. (rationale: since nobody in the kernel is using
  57. this in a module, there is a pretty good chance it's actually the
  58. wrong interface to use). If you really need the symbol, please send a
  59. mail to the linux kernel mailing list mentioning the symbol and why
  60. you really need it, and what the merge plan to the mainline kernel for
  61. your module is.
  62. config DEBUG_FS
  63. bool "Debug Filesystem"
  64. depends on SYSFS
  65. help
  66. debugfs is a virtual file system that kernel developers use to put
  67. debugging files into. Enable this option to be able to read and
  68. write to these files.
  69. For detailed documentation on the debugfs API, see
  70. Documentation/DocBook/filesystems.
  71. If unsure, say N.
  72. config HEADERS_CHECK
  73. bool "Run 'make headers_check' when building vmlinux"
  74. depends on !UML
  75. help
  76. This option will extract the user-visible kernel headers whenever
  77. building the kernel, and will run basic sanity checks on them to
  78. ensure that exported files do not attempt to include files which
  79. were not exported, etc.
  80. If you're making modifications to header files which are
  81. relevant for userspace, say 'Y', and check the headers
  82. exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  83. your build tree), to make sure they're suitable.
  84. config DEBUG_SECTION_MISMATCH
  85. bool "Enable full Section mismatch analysis"
  86. depends on UNDEFINED
  87. # This option is on purpose disabled for now.
  88. # It will be enabled when we are down to a resonable number
  89. # of section mismatch warnings (< 10 for an allyesconfig build)
  90. help
  91. The section mismatch analysis checks if there are illegal
  92. references from one section to another section.
  93. Linux will during link or during runtime drop some sections
  94. and any use of code/data previously in these sections will
  95. most likely result in an oops.
  96. In the code functions and variables are annotated with
  97. __init, __devinit etc. (see full list in include/linux/init.h)
  98. which results in the code/data being placed in specific sections.
  99. The section mismatch analysis is always done after a full
  100. kernel build but enabling this option will in addition
  101. do the following:
  102. - Add the option -fno-inline-functions-called-once to gcc
  103. When inlining a function annotated __init in a non-init
  104. function we would lose the section information and thus
  105. the analysis would not catch the illegal reference.
  106. This option tells gcc to inline less but will also
  107. result in a larger kernel.
  108. - Run the section mismatch analysis for each module/built-in.o
  109. When we run the section mismatch analysis on vmlinux.o we
  110. lose valueble information about where the mismatch was
  111. introduced.
  112. Running the analysis for each module/built-in.o file
  113. will tell where the mismatch happens much closer to the
  114. source. The drawback is that we will report the same
  115. mismatch at least twice.
  116. - Enable verbose reporting from modpost to help solving
  117. the section mismatches reported.
  118. config DEBUG_KERNEL
  119. bool "Kernel debugging"
  120. help
  121. Say Y here if you are developing drivers or trying to debug and
  122. identify kernel problems.
  123. config DEBUG_SHIRQ
  124. bool "Debug shared IRQ handlers"
  125. depends on DEBUG_KERNEL && GENERIC_HARDIRQS
  126. help
  127. Enable this to generate a spurious interrupt as soon as a shared
  128. interrupt handler is registered, and just before one is deregistered.
  129. Drivers ought to be able to handle interrupts coming in at those
  130. points; some don't and need to be caught.
  131. config DETECT_SOFTLOCKUP
  132. bool "Detect Soft Lockups"
  133. depends on DEBUG_KERNEL && !S390
  134. default y
  135. help
  136. Say Y here to enable the kernel to detect "soft lockups",
  137. which are bugs that cause the kernel to loop in kernel
  138. mode for more than 60 seconds, without giving other tasks a
  139. chance to run.
  140. When a soft-lockup is detected, the kernel will print the
  141. current stack trace (which you should report), but the
  142. system will stay locked up. This feature has negligible
  143. overhead.
  144. (Note that "hard lockups" are separate type of bugs that
  145. can be detected via the NMI-watchdog, on platforms that
  146. support it.)
  147. config BOOTPARAM_SOFTLOCKUP_PANIC
  148. bool "Panic (Reboot) On Soft Lockups"
  149. depends on DETECT_SOFTLOCKUP
  150. help
  151. Say Y here to enable the kernel to panic on "soft lockups",
  152. which are bugs that cause the kernel to loop in kernel
  153. mode for more than 60 seconds, without giving other tasks a
  154. chance to run.
  155. The panic can be used in combination with panic_timeout,
  156. to cause the system to reboot automatically after a
  157. lockup has been detected. This feature is useful for
  158. high-availability systems that have uptime guarantees and
  159. where a lockup must be resolved ASAP.
  160. Say N if unsure.
  161. config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
  162. int
  163. depends on DETECT_SOFTLOCKUP
  164. range 0 1
  165. default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
  166. default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
  167. config DETECT_HUNG_TASK
  168. bool "Detect Hung Tasks"
  169. depends on DEBUG_KERNEL
  170. default DETECT_SOFTLOCKUP
  171. help
  172. Say Y here to enable the kernel to detect "hung tasks",
  173. which are bugs that cause the task to be stuck in
  174. uninterruptible "D" state indefinitiley.
  175. When a hung task is detected, the kernel will print the
  176. current stack trace (which you should report), but the
  177. task will stay in uninterruptible state. If lockdep is
  178. enabled then all held locks will also be reported. This
  179. feature has negligible overhead.
  180. config BOOTPARAM_HUNG_TASK_PANIC
  181. bool "Panic (Reboot) On Hung Tasks"
  182. depends on DETECT_HUNG_TASK
  183. help
  184. Say Y here to enable the kernel to panic on "hung tasks",
  185. which are bugs that cause the kernel to leave a task stuck
  186. in uninterruptible "D" state.
  187. The panic can be used in combination with panic_timeout,
  188. to cause the system to reboot automatically after a
  189. hung task has been detected. This feature is useful for
  190. high-availability systems that have uptime guarantees and
  191. where a hung tasks must be resolved ASAP.
  192. Say N if unsure.
  193. config BOOTPARAM_HUNG_TASK_PANIC_VALUE
  194. int
  195. depends on DETECT_HUNG_TASK
  196. range 0 1
  197. default 0 if !BOOTPARAM_HUNG_TASK_PANIC
  198. default 1 if BOOTPARAM_HUNG_TASK_PANIC
  199. config SCHED_DEBUG
  200. bool "Collect scheduler debugging info"
  201. depends on DEBUG_KERNEL && PROC_FS
  202. default y
  203. help
  204. If you say Y here, the /proc/sched_debug file will be provided
  205. that can help debug the scheduler. The runtime overhead of this
  206. option is minimal.
  207. config SCHEDSTATS
  208. bool "Collect scheduler statistics"
  209. depends on DEBUG_KERNEL && PROC_FS
  210. help
  211. If you say Y here, additional code will be inserted into the
  212. scheduler and related routines to collect statistics about
  213. scheduler behavior and provide them in /proc/schedstat. These
  214. stats may be useful for both tuning and debugging the scheduler
  215. If you aren't debugging the scheduler or trying to tune a specific
  216. application, you can say N to avoid the very slight overhead
  217. this adds.
  218. config TIMER_STATS
  219. bool "Collect kernel timers statistics"
  220. depends on DEBUG_KERNEL && PROC_FS
  221. help
  222. If you say Y here, additional code will be inserted into the
  223. timer routines to collect statistics about kernel timers being
  224. reprogrammed. The statistics can be read from /proc/timer_stats.
  225. The statistics collection is started by writing 1 to /proc/timer_stats,
  226. writing 0 stops it. This feature is useful to collect information
  227. about timer usage patterns in kernel and userspace. This feature
  228. is lightweight if enabled in the kernel config but not activated
  229. (it defaults to deactivated on bootup and will only be activated
  230. if some application like powertop activates it explicitly).
  231. config DEBUG_OBJECTS
  232. bool "Debug object operations"
  233. depends on DEBUG_KERNEL
  234. help
  235. If you say Y here, additional code will be inserted into the
  236. kernel to track the life time of various objects and validate
  237. the operations on those objects.
  238. config DEBUG_OBJECTS_SELFTEST
  239. bool "Debug objects selftest"
  240. depends on DEBUG_OBJECTS
  241. help
  242. This enables the selftest of the object debug code.
  243. config DEBUG_OBJECTS_FREE
  244. bool "Debug objects in freed memory"
  245. depends on DEBUG_OBJECTS
  246. help
  247. This enables checks whether a k/v free operation frees an area
  248. which contains an object which has not been deactivated
  249. properly. This can make kmalloc/kfree-intensive workloads
  250. much slower.
  251. config DEBUG_OBJECTS_TIMERS
  252. bool "Debug timer objects"
  253. depends on DEBUG_OBJECTS
  254. help
  255. If you say Y here, additional code will be inserted into the
  256. timer routines to track the life time of timer objects and
  257. validate the timer operations.
  258. config DEBUG_OBJECTS_ENABLE_DEFAULT
  259. int "debug_objects bootup default value (0-1)"
  260. range 0 1
  261. default "1"
  262. depends on DEBUG_OBJECTS
  263. help
  264. Debug objects boot parameter default value
  265. config DEBUG_SLAB
  266. bool "Debug slab memory allocations"
  267. depends on DEBUG_KERNEL && SLAB
  268. help
  269. Say Y here to have the kernel do limited verification on memory
  270. allocation as well as poisoning memory on free to catch use of freed
  271. memory. This can make kmalloc/kfree-intensive workloads much slower.
  272. config DEBUG_SLAB_LEAK
  273. bool "Memory leak debugging"
  274. depends on DEBUG_SLAB
  275. config SLUB_DEBUG_ON
  276. bool "SLUB debugging on by default"
  277. depends on SLUB && SLUB_DEBUG
  278. default n
  279. help
  280. Boot with debugging on by default. SLUB boots by default with
  281. the runtime debug capabilities switched off. Enabling this is
  282. equivalent to specifying the "slub_debug" parameter on boot.
  283. There is no support for more fine grained debug control like
  284. possible with slub_debug=xxx. SLUB debugging may be switched
  285. off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
  286. "slub_debug=-".
  287. config SLUB_STATS
  288. default n
  289. bool "Enable SLUB performance statistics"
  290. depends on SLUB && SLUB_DEBUG && SYSFS
  291. help
  292. SLUB statistics are useful to debug SLUBs allocation behavior in
  293. order find ways to optimize the allocator. This should never be
  294. enabled for production use since keeping statistics slows down
  295. the allocator by a few percentage points. The slabinfo command
  296. supports the determination of the most active slabs to figure
  297. out which slabs are relevant to a particular load.
  298. Try running: slabinfo -DA
  299. config DEBUG_PREEMPT
  300. bool "Debug preemptible kernel"
  301. depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
  302. default y
  303. help
  304. If you say Y here then the kernel will use a debug variant of the
  305. commonly used smp_processor_id() function and will print warnings
  306. if kernel code uses it in a preemption-unsafe way. Also, the kernel
  307. will detect preemption count underflows.
  308. config DEBUG_RT_MUTEXES
  309. bool "RT Mutex debugging, deadlock detection"
  310. depends on DEBUG_KERNEL && RT_MUTEXES
  311. help
  312. This allows rt mutex semantics violations and rt mutex related
  313. deadlocks (lockups) to be detected and reported automatically.
  314. config DEBUG_PI_LIST
  315. bool
  316. default y
  317. depends on DEBUG_RT_MUTEXES
  318. config RT_MUTEX_TESTER
  319. bool "Built-in scriptable tester for rt-mutexes"
  320. depends on DEBUG_KERNEL && RT_MUTEXES
  321. help
  322. This option enables a rt-mutex tester.
  323. config DEBUG_SPINLOCK
  324. bool "Spinlock and rw-lock debugging: basic checks"
  325. depends on DEBUG_KERNEL
  326. help
  327. Say Y here and build SMP to catch missing spinlock initialization
  328. and certain other kinds of spinlock errors commonly made. This is
  329. best used in conjunction with the NMI watchdog so that spinlock
  330. deadlocks are also debuggable.
  331. config DEBUG_MUTEXES
  332. bool "Mutex debugging: basic checks"
  333. depends on DEBUG_KERNEL
  334. help
  335. This feature allows mutex semantics violations to be detected and
  336. reported.
  337. config DEBUG_LOCK_ALLOC
  338. bool "Lock debugging: detect incorrect freeing of live locks"
  339. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  340. select DEBUG_SPINLOCK
  341. select DEBUG_MUTEXES
  342. select LOCKDEP
  343. help
  344. This feature will check whether any held lock (spinlock, rwlock,
  345. mutex or rwsem) is incorrectly freed by the kernel, via any of the
  346. memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
  347. vfree(), etc.), whether a live lock is incorrectly reinitialized via
  348. spin_lock_init()/mutex_init()/etc., or whether there is any lock
  349. held during task exit.
  350. config PROVE_LOCKING
  351. bool "Lock debugging: prove locking correctness"
  352. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  353. select LOCKDEP
  354. select DEBUG_SPINLOCK
  355. select DEBUG_MUTEXES
  356. select DEBUG_LOCK_ALLOC
  357. default n
  358. help
  359. This feature enables the kernel to prove that all locking
  360. that occurs in the kernel runtime is mathematically
  361. correct: that under no circumstance could an arbitrary (and
  362. not yet triggered) combination of observed locking
  363. sequences (on an arbitrary number of CPUs, running an
  364. arbitrary number of tasks and interrupt contexts) cause a
  365. deadlock.
  366. In short, this feature enables the kernel to report locking
  367. related deadlocks before they actually occur.
  368. The proof does not depend on how hard and complex a
  369. deadlock scenario would be to trigger: how many
  370. participant CPUs, tasks and irq-contexts would be needed
  371. for it to trigger. The proof also does not depend on
  372. timing: if a race and a resulting deadlock is possible
  373. theoretically (no matter how unlikely the race scenario
  374. is), it will be proven so and will immediately be
  375. reported by the kernel (once the event is observed that
  376. makes the deadlock theoretically possible).
  377. If a deadlock is impossible (i.e. the locking rules, as
  378. observed by the kernel, are mathematically correct), the
  379. kernel reports nothing.
  380. NOTE: this feature can also be enabled for rwlocks, mutexes
  381. and rwsems - in which case all dependencies between these
  382. different locking variants are observed and mapped too, and
  383. the proof of observed correctness is also maintained for an
  384. arbitrary combination of these separate locking variants.
  385. For more details, see Documentation/lockdep-design.txt.
  386. config LOCKDEP
  387. bool
  388. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  389. select STACKTRACE
  390. select FRAME_POINTER if !X86 && !MIPS && !PPC && !ARM_UNWIND
  391. select KALLSYMS
  392. select KALLSYMS_ALL
  393. config LOCK_STAT
  394. bool "Lock usage statistics"
  395. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  396. select LOCKDEP
  397. select DEBUG_SPINLOCK
  398. select DEBUG_MUTEXES
  399. select DEBUG_LOCK_ALLOC
  400. default n
  401. help
  402. This feature enables tracking lock contention points
  403. For more details, see Documentation/lockstat.txt
  404. config DEBUG_LOCKDEP
  405. bool "Lock dependency engine debugging"
  406. depends on DEBUG_KERNEL && LOCKDEP
  407. help
  408. If you say Y here, the lock dependency engine will do
  409. additional runtime checks to debug itself, at the price
  410. of more runtime overhead.
  411. config TRACE_IRQFLAGS
  412. depends on DEBUG_KERNEL
  413. bool
  414. default y
  415. depends on TRACE_IRQFLAGS_SUPPORT
  416. depends on PROVE_LOCKING
  417. config DEBUG_SPINLOCK_SLEEP
  418. bool "Spinlock debugging: sleep-inside-spinlock checking"
  419. depends on DEBUG_KERNEL
  420. help
  421. If you say Y here, various routines which may sleep will become very
  422. noisy if they are called with a spinlock held.
  423. config DEBUG_LOCKING_API_SELFTESTS
  424. bool "Locking API boot-time self-tests"
  425. depends on DEBUG_KERNEL
  426. help
  427. Say Y here if you want the kernel to run a short self-test during
  428. bootup. The self-test checks whether common types of locking bugs
  429. are detected by debugging mechanisms or not. (if you disable
  430. lock debugging then those bugs wont be detected of course.)
  431. The following locking APIs are covered: spinlocks, rwlocks,
  432. mutexes and rwsems.
  433. config STACKTRACE
  434. bool
  435. depends on STACKTRACE_SUPPORT
  436. config DEBUG_KOBJECT
  437. bool "kobject debugging"
  438. depends on DEBUG_KERNEL
  439. help
  440. If you say Y here, some extra kobject debugging messages will be sent
  441. to the syslog.
  442. config DEBUG_HIGHMEM
  443. bool "Highmem debugging"
  444. depends on DEBUG_KERNEL && HIGHMEM
  445. help
  446. This options enables addition error checking for high memory systems.
  447. Disable for production systems.
  448. config DEBUG_BUGVERBOSE
  449. bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
  450. depends on BUG
  451. depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
  452. FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
  453. default !EMBEDDED
  454. help
  455. Say Y here to make BUG() panics output the file name and line number
  456. of the BUG call as well as the EIP and oops trace. This aids
  457. debugging but costs about 70-100K of memory.
  458. config DEBUG_INFO
  459. bool "Compile the kernel with debug info"
  460. depends on DEBUG_KERNEL
  461. help
  462. If you say Y here the resulting kernel image will include
  463. debugging info resulting in a larger kernel image.
  464. This adds debug symbols to the kernel and modules (gcc -g), and
  465. is needed if you intend to use kernel crashdump or binary object
  466. tools like crash, kgdb, LKCD, gdb, etc on the kernel.
  467. Say Y here only if you plan to debug the kernel.
  468. If unsure, say N.
  469. config DEBUG_VM
  470. bool "Debug VM"
  471. depends on DEBUG_KERNEL
  472. help
  473. Enable this to turn on extended checks in the virtual-memory system
  474. that may impact performance.
  475. If unsure, say N.
  476. config DEBUG_VIRTUAL
  477. bool "Debug VM translations"
  478. depends on DEBUG_KERNEL && X86
  479. help
  480. Enable some costly sanity checks in virtual to page code. This can
  481. catch mistakes with virt_to_page() and friends.
  482. If unsure, say N.
  483. config DEBUG_NOMMU_REGIONS
  484. bool "Debug the global anon/private NOMMU mapping region tree"
  485. depends on DEBUG_KERNEL && !MMU
  486. help
  487. This option causes the global tree of anonymous and private mapping
  488. regions to be regularly checked for invalid topology.
  489. config DEBUG_WRITECOUNT
  490. bool "Debug filesystem writers count"
  491. depends on DEBUG_KERNEL
  492. help
  493. Enable this to catch wrong use of the writers count in struct
  494. vfsmount. This will increase the size of each file struct by
  495. 32 bits.
  496. If unsure, say N.
  497. config DEBUG_MEMORY_INIT
  498. bool "Debug memory initialisation" if EMBEDDED
  499. default !EMBEDDED
  500. help
  501. Enable this for additional checks during memory initialisation.
  502. The sanity checks verify aspects of the VM such as the memory model
  503. and other information provided by the architecture. Verbose
  504. information will be printed at KERN_DEBUG loglevel depending
  505. on the mminit_loglevel= command-line option.
  506. If unsure, say Y
  507. config DEBUG_LIST
  508. bool "Debug linked list manipulation"
  509. depends on DEBUG_KERNEL
  510. help
  511. Enable this to turn on extended checks in the linked-list
  512. walking routines.
  513. If unsure, say N.
  514. config DEBUG_SG
  515. bool "Debug SG table operations"
  516. depends on DEBUG_KERNEL
  517. help
  518. Enable this to turn on checks on scatter-gather tables. This can
  519. help find problems with drivers that do not properly initialize
  520. their sg tables.
  521. If unsure, say N.
  522. config DEBUG_NOTIFIERS
  523. bool "Debug notifier call chains"
  524. depends on DEBUG_KERNEL
  525. help
  526. Enable this to turn on sanity checking for notifier call chains.
  527. This is most useful for kernel developers to make sure that
  528. modules properly unregister themselves from notifier chains.
  529. This is a relatively cheap check but if you care about maximum
  530. performance, say N.
  531. #
  532. # Select this config option from the architecture Kconfig, if it
  533. # it is preferred to always offer frame pointers as a config
  534. # option on the architecture (regardless of KERNEL_DEBUG):
  535. #
  536. config ARCH_WANT_FRAME_POINTERS
  537. bool
  538. help
  539. config FRAME_POINTER
  540. bool "Compile the kernel with frame pointers"
  541. depends on DEBUG_KERNEL && \
  542. (CRIS || M68K || M68KNOMMU || FRV || UML || S390 || \
  543. AVR32 || SUPERH || BLACKFIN || MN10300) || \
  544. ARCH_WANT_FRAME_POINTERS
  545. default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
  546. help
  547. If you say Y here the resulting kernel image will be slightly
  548. larger and slower, but it gives very useful debugging information
  549. in case of kernel bugs. (precise oopses/stacktraces/warnings)
  550. config BOOT_PRINTK_DELAY
  551. bool "Delay each boot printk message by N milliseconds"
  552. depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
  553. help
  554. This build option allows you to read kernel boot messages
  555. by inserting a short delay after each one. The delay is
  556. specified in milliseconds on the kernel command line,
  557. using "boot_delay=N".
  558. It is likely that you would also need to use "lpj=M" to preset
  559. the "loops per jiffie" value.
  560. See a previous boot log for the "lpj" value to use for your
  561. system, and then set "lpj=M" before setting "boot_delay=N".
  562. NOTE: Using this option may adversely affect SMP systems.
  563. I.e., processors other than the first one may not boot up.
  564. BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
  565. what it believes to be lockup conditions.
  566. config RCU_TORTURE_TEST
  567. tristate "torture tests for RCU"
  568. depends on DEBUG_KERNEL
  569. default n
  570. help
  571. This option provides a kernel module that runs torture tests
  572. on the RCU infrastructure. The kernel module may be built
  573. after the fact on the running kernel to be tested, if desired.
  574. Say Y here if you want RCU torture tests to be built into
  575. the kernel.
  576. Say M if you want the RCU torture tests to build as a module.
  577. Say N if you are unsure.
  578. config RCU_TORTURE_TEST_RUNNABLE
  579. bool "torture tests for RCU runnable by default"
  580. depends on RCU_TORTURE_TEST = y
  581. default n
  582. help
  583. This option provides a way to build the RCU torture tests
  584. directly into the kernel without them starting up at boot
  585. time. You can use /proc/sys/kernel/rcutorture_runnable
  586. to manually override this setting. This /proc file is
  587. available only when the RCU torture tests have been built
  588. into the kernel.
  589. Say Y here if you want the RCU torture tests to start during
  590. boot (you probably don't).
  591. Say N here if you want the RCU torture tests to start only
  592. after being manually enabled via /proc.
  593. config RCU_CPU_STALL_DETECTOR
  594. bool "Check for stalled CPUs delaying RCU grace periods"
  595. depends on CLASSIC_RCU || TREE_RCU
  596. default n
  597. help
  598. This option causes RCU to printk information on which
  599. CPUs are delaying the current grace period, but only when
  600. the grace period extends for excessive time periods.
  601. Say Y if you want RCU to perform such checks.
  602. Say N if you are unsure.
  603. config KPROBES_SANITY_TEST
  604. bool "Kprobes sanity tests"
  605. depends on DEBUG_KERNEL
  606. depends on KPROBES
  607. default n
  608. help
  609. This option provides for testing basic kprobes functionality on
  610. boot. A sample kprobe, jprobe and kretprobe are inserted and
  611. verified for functionality.
  612. Say N if you are unsure.
  613. config BACKTRACE_SELF_TEST
  614. tristate "Self test for the backtrace code"
  615. depends on DEBUG_KERNEL
  616. default n
  617. help
  618. This option provides a kernel module that can be used to test
  619. the kernel stack backtrace code. This option is not useful
  620. for distributions or general kernels, but only for kernel
  621. developers working on architecture code.
  622. Note that if you want to also test saved backtraces, you will
  623. have to enable STACKTRACE as well.
  624. Say N if you are unsure.
  625. config DEBUG_BLOCK_EXT_DEVT
  626. bool "Force extended block device numbers and spread them"
  627. depends on DEBUG_KERNEL
  628. depends on BLOCK
  629. default n
  630. help
  631. BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
  632. SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
  633. YOU ARE DOING. Distros, please enable this and fix whatever
  634. is broken.
  635. Conventionally, block device numbers are allocated from
  636. predetermined contiguous area. However, extended block area
  637. may introduce non-contiguous block device numbers. This
  638. option forces most block device numbers to be allocated from
  639. the extended space and spreads them to discover kernel or
  640. userland code paths which assume predetermined contiguous
  641. device number allocation.
  642. Note that turning on this debug option shuffles all the
  643. device numbers for all IDE and SCSI devices including libata
  644. ones, so root partition specified using device number
  645. directly (via rdev or root=MAJ:MIN) won't work anymore.
  646. Textual device names (root=/dev/sdXn) will continue to work.
  647. Say N if you are unsure.
  648. config LKDTM
  649. tristate "Linux Kernel Dump Test Tool Module"
  650. depends on DEBUG_KERNEL
  651. depends on KPROBES
  652. depends on BLOCK
  653. default n
  654. help
  655. This module enables testing of the different dumping mechanisms by
  656. inducing system failures at predefined crash points.
  657. If you don't need it: say N
  658. Choose M here to compile this code as a module. The module will be
  659. called lkdtm.
  660. Documentation on how to use the module can be found in
  661. drivers/misc/lkdtm.c
  662. config FAULT_INJECTION
  663. bool "Fault-injection framework"
  664. depends on DEBUG_KERNEL
  665. help
  666. Provide fault-injection framework.
  667. For more details, see Documentation/fault-injection/.
  668. config FAILSLAB
  669. bool "Fault-injection capability for kmalloc"
  670. depends on FAULT_INJECTION
  671. depends on SLAB || SLUB
  672. help
  673. Provide fault-injection capability for kmalloc.
  674. config FAIL_PAGE_ALLOC
  675. bool "Fault-injection capabilitiy for alloc_pages()"
  676. depends on FAULT_INJECTION
  677. help
  678. Provide fault-injection capability for alloc_pages().
  679. config FAIL_MAKE_REQUEST
  680. bool "Fault-injection capability for disk IO"
  681. depends on FAULT_INJECTION && BLOCK
  682. help
  683. Provide fault-injection capability for disk IO.
  684. config FAIL_IO_TIMEOUT
  685. bool "Faul-injection capability for faking disk interrupts"
  686. depends on FAULT_INJECTION && BLOCK
  687. help
  688. Provide fault-injection capability on end IO handling. This
  689. will make the block layer "forget" an interrupt as configured,
  690. thus exercising the error handling.
  691. Only works with drivers that use the generic timeout handling,
  692. for others it wont do anything.
  693. config FAULT_INJECTION_DEBUG_FS
  694. bool "Debugfs entries for fault-injection capabilities"
  695. depends on FAULT_INJECTION && SYSFS && DEBUG_FS
  696. help
  697. Enable configuration of fault-injection capabilities via debugfs.
  698. config FAULT_INJECTION_STACKTRACE_FILTER
  699. bool "stacktrace filter for fault-injection capabilities"
  700. depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
  701. depends on !X86_64
  702. select STACKTRACE
  703. select FRAME_POINTER if !PPC
  704. help
  705. Provide stacktrace filter for fault-injection capabilities
  706. config LATENCYTOP
  707. bool "Latency measuring infrastructure"
  708. select FRAME_POINTER if !MIPS && !PPC
  709. select KALLSYMS
  710. select KALLSYMS_ALL
  711. select STACKTRACE
  712. select SCHEDSTATS
  713. select SCHED_DEBUG
  714. depends on HAVE_LATENCYTOP_SUPPORT
  715. help
  716. Enable this option if you want to use the LatencyTOP tool
  717. to find out which userspace is blocking on what kernel operations.
  718. config SYSCTL_SYSCALL_CHECK
  719. bool "Sysctl checks"
  720. depends on SYSCTL_SYSCALL
  721. ---help---
  722. sys_sysctl uses binary paths that have been found challenging
  723. to properly maintain and use. This enables checks that help
  724. you to keep things correct.
  725. source mm/Kconfig.debug
  726. source kernel/trace/Kconfig
  727. config PROVIDE_OHCI1394_DMA_INIT
  728. bool "Remote debugging over FireWire early on boot"
  729. depends on PCI && X86
  730. help
  731. If you want to debug problems which hang or crash the kernel early
  732. on boot and the crashing machine has a FireWire port, you can use
  733. this feature to remotely access the memory of the crashed machine
  734. over FireWire. This employs remote DMA as part of the OHCI1394
  735. specification which is now the standard for FireWire controllers.
  736. With remote DMA, you can monitor the printk buffer remotely using
  737. firescope and access all memory below 4GB using fireproxy from gdb.
  738. Even controlling a kernel debugger is possible using remote DMA.
  739. Usage:
  740. If ohci1394_dma=early is used as boot parameter, it will initialize
  741. all OHCI1394 controllers which are found in the PCI config space.
  742. As all changes to the FireWire bus such as enabling and disabling
  743. devices cause a bus reset and thereby disable remote DMA for all
  744. devices, be sure to have the cable plugged and FireWire enabled on
  745. the debugging host before booting the debug target for debugging.
  746. This code (~1k) is freed after boot. By then, the firewire stack
  747. in charge of the OHCI-1394 controllers should be used instead.
  748. See Documentation/debugging-via-ohci1394.txt for more information.
  749. config FIREWIRE_OHCI_REMOTE_DMA
  750. bool "Remote debugging over FireWire with firewire-ohci"
  751. depends on FIREWIRE_OHCI
  752. help
  753. This option lets you use the FireWire bus for remote debugging
  754. with help of the firewire-ohci driver. It enables unfiltered
  755. remote DMA in firewire-ohci.
  756. See Documentation/debugging-via-ohci1394.txt for more information.
  757. If unsure, say N.
  758. config BUILD_DOCSRC
  759. bool "Build targets in Documentation/ tree"
  760. depends on HEADERS_CHECK
  761. help
  762. This option attempts to build objects from the source files in the
  763. kernel Documentation/ tree.
  764. Say N if you are unsure.
  765. config DYNAMIC_DEBUG
  766. bool "Enable dynamic printk() support"
  767. default n
  768. depends on PRINTK
  769. depends on DEBUG_FS
  770. select PRINTK_DEBUG
  771. help
  772. Compiles debug level messages into the kernel, which would not
  773. otherwise be available at runtime. These messages can then be
  774. enabled/disabled based on various levels of scope - per source file,
  775. function, module, format string, and line number. This mechanism
  776. implicitly enables all pr_debug() and dev_dbg() calls. The impact of
  777. this compile option is a larger kernel text size of about 2%.
  778. Usage:
  779. Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
  780. which is contained in the 'debugfs' filesystem. Thus, the debugfs
  781. filesystem must first be mounted before making use of this feature.
  782. We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
  783. file contains a list of the debug statements that can be enabled. The
  784. format for each line of the file is:
  785. filename:lineno [module]function flags format
  786. filename : source file of the debug statement
  787. lineno : line number of the debug statement
  788. module : module that contains the debug statement
  789. function : function that contains the debug statement
  790. flags : 'p' means the line is turned 'on' for printing
  791. format : the format used for the debug statement
  792. From a live system:
  793. nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
  794. # filename:lineno [module]function flags format
  795. fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
  796. fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
  797. fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
  798. Example usage:
  799. // enable the message at line 1603 of file svcsock.c
  800. nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
  801. <debugfs>/dynamic_debug/ddebug
  802. // enable all the messages in file svcsock.c
  803. nullarbor:~ # echo -n 'file svcsock.c +p' >
  804. <debugfs>/dynamic_debug/ddebug
  805. // enable all the messages in the NFS server module
  806. nullarbor:~ # echo -n 'module nfsd +p' >
  807. <debugfs>/dynamic_debug/ddebug
  808. // enable all 12 messages in the function svc_process()
  809. nullarbor:~ # echo -n 'func svc_process +p' >
  810. <debugfs>/dynamic_debug/ddebug
  811. // disable all 12 messages in the function svc_process()
  812. nullarbor:~ # echo -n 'func svc_process -p' >
  813. <debugfs>/dynamic_debug/ddebug
  814. See Documentation/dynamic-debug-howto.txt for additional information.
  815. config DMA_API_DEBUG
  816. bool "Enable debugging of DMA-API usage"
  817. depends on HAVE_DMA_API_DEBUG
  818. help
  819. Enable this option to debug the use of the DMA API by device drivers.
  820. With this option you will be able to detect common bugs in device
  821. drivers like double-freeing of DMA mappings or freeing mappings that
  822. were never allocated.
  823. This option causes a performance degredation. Use only if you want
  824. to debug device drivers. If unsure, say N.
  825. source "samples/Kconfig"
  826. source "lib/Kconfig.kgdb"