Kconfig.debug 36 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. depends on SYSFS
  72. help
  73. debugfs is a virtual file system that kernel developers use to put
  74. debugging files into. Enable this option to be able to read and
  75. write to these files.
  76. For detailed documentation on the debugfs API, see
  77. Documentation/DocBook/filesystems.
  78. If unsure, say N.
  79. config HEADERS_CHECK
  80. bool "Run 'make headers_check' when building vmlinux"
  81. depends on !UML
  82. help
  83. This option will extract the user-visible kernel headers whenever
  84. building the kernel, and will run basic sanity checks on them to
  85. ensure that exported files do not attempt to include files which
  86. were not exported, etc.
  87. If you're making modifications to header files which are
  88. relevant for userspace, say 'Y', and check the headers
  89. exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  90. your build tree), to make sure they're suitable.
  91. config DEBUG_SECTION_MISMATCH
  92. bool "Enable full Section mismatch analysis"
  93. depends on UNDEFINED
  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 DETECT_SOFTLOCKUP
  139. bool "Detect Soft Lockups"
  140. depends on DEBUG_KERNEL && !S390
  141. default y
  142. help
  143. Say Y here to enable the kernel to detect "soft lockups",
  144. which 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.
  147. When a soft-lockup is detected, the kernel will print the
  148. current stack trace (which you should report), but the
  149. system will stay locked up. This feature has negligible
  150. overhead.
  151. (Note that "hard lockups" are separate type of bugs that
  152. can be detected via the NMI-watchdog, on platforms that
  153. support it.)
  154. config BOOTPARAM_SOFTLOCKUP_PANIC
  155. bool "Panic (Reboot) On Soft Lockups"
  156. depends on DETECT_SOFTLOCKUP
  157. help
  158. Say Y here to enable the kernel to panic on "soft lockups",
  159. which are bugs that cause the kernel to loop in kernel
  160. mode for more than 60 seconds, without giving other tasks a
  161. chance to run.
  162. The panic can be used in combination with panic_timeout,
  163. to cause the system to reboot automatically after a
  164. lockup has been detected. This feature is useful for
  165. high-availability systems that have uptime guarantees and
  166. where a lockup must be resolved ASAP.
  167. Say N if unsure.
  168. config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
  169. int
  170. depends on DETECT_SOFTLOCKUP
  171. range 0 1
  172. default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
  173. default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
  174. config DETECT_HUNG_TASK
  175. bool "Detect Hung Tasks"
  176. depends on DEBUG_KERNEL
  177. default DETECT_SOFTLOCKUP
  178. help
  179. Say Y here to enable the kernel to detect "hung tasks",
  180. which are bugs that cause the task to be stuck in
  181. uninterruptible "D" state indefinitiley.
  182. When a hung task is detected, the kernel will print the
  183. current stack trace (which you should report), but the
  184. task will stay in uninterruptible state. If lockdep is
  185. enabled then all held locks will also be reported. This
  186. feature has negligible overhead.
  187. config BOOTPARAM_HUNG_TASK_PANIC
  188. bool "Panic (Reboot) On Hung Tasks"
  189. depends on DETECT_HUNG_TASK
  190. help
  191. Say Y here to enable the kernel to panic on "hung tasks",
  192. which are bugs that cause the kernel to leave a task stuck
  193. in uninterruptible "D" state.
  194. The panic can be used in combination with panic_timeout,
  195. to cause the system to reboot automatically after a
  196. hung task has been detected. This feature is useful for
  197. high-availability systems that have uptime guarantees and
  198. where a hung tasks must be resolved ASAP.
  199. Say N if unsure.
  200. config BOOTPARAM_HUNG_TASK_PANIC_VALUE
  201. int
  202. depends on DETECT_HUNG_TASK
  203. range 0 1
  204. default 0 if !BOOTPARAM_HUNG_TASK_PANIC
  205. default 1 if BOOTPARAM_HUNG_TASK_PANIC
  206. config SCHED_DEBUG
  207. bool "Collect scheduler debugging info"
  208. depends on DEBUG_KERNEL && PROC_FS
  209. default y
  210. help
  211. If you say Y here, the /proc/sched_debug file will be provided
  212. that can help debug the scheduler. The runtime overhead of this
  213. option is minimal.
  214. config SCHEDSTATS
  215. bool "Collect scheduler statistics"
  216. depends on DEBUG_KERNEL && PROC_FS
  217. help
  218. If you say Y here, additional code will be inserted into the
  219. scheduler and related routines to collect statistics about
  220. scheduler behavior and provide them in /proc/schedstat. These
  221. stats may be useful for both tuning and debugging the scheduler
  222. If you aren't debugging the scheduler or trying to tune a specific
  223. application, you can say N to avoid the very slight overhead
  224. this adds.
  225. config TIMER_STATS
  226. bool "Collect kernel timers statistics"
  227. depends on DEBUG_KERNEL && PROC_FS
  228. help
  229. If you say Y here, additional code will be inserted into the
  230. timer routines to collect statistics about kernel timers being
  231. reprogrammed. The statistics can be read from /proc/timer_stats.
  232. The statistics collection is started by writing 1 to /proc/timer_stats,
  233. writing 0 stops it. This feature is useful to collect information
  234. about timer usage patterns in kernel and userspace. This feature
  235. is lightweight if enabled in the kernel config but not activated
  236. (it defaults to deactivated on bootup and will only be activated
  237. if some application like powertop activates it explicitly).
  238. config DEBUG_OBJECTS
  239. bool "Debug object operations"
  240. depends on DEBUG_KERNEL
  241. help
  242. If you say Y here, additional code will be inserted into the
  243. kernel to track the life time of various objects and validate
  244. the operations on those objects.
  245. config DEBUG_OBJECTS_SELFTEST
  246. bool "Debug objects selftest"
  247. depends on DEBUG_OBJECTS
  248. help
  249. This enables the selftest of the object debug code.
  250. config DEBUG_OBJECTS_FREE
  251. bool "Debug objects in freed memory"
  252. depends on DEBUG_OBJECTS
  253. help
  254. This enables checks whether a k/v free operation frees an area
  255. which contains an object which has not been deactivated
  256. properly. This can make kmalloc/kfree-intensive workloads
  257. much slower.
  258. config DEBUG_OBJECTS_TIMERS
  259. bool "Debug timer objects"
  260. depends on DEBUG_OBJECTS
  261. help
  262. If you say Y here, additional code will be inserted into the
  263. timer routines to track the life time of timer objects and
  264. validate the timer operations.
  265. config DEBUG_OBJECTS_WORK
  266. bool "Debug work objects"
  267. depends on DEBUG_OBJECTS
  268. help
  269. If you say Y here, additional code will be inserted into the
  270. work queue routines to track the life time of work objects and
  271. validate the work operations.
  272. config DEBUG_OBJECTS_ENABLE_DEFAULT
  273. int "debug_objects bootup default value (0-1)"
  274. range 0 1
  275. default "1"
  276. depends on DEBUG_OBJECTS
  277. help
  278. Debug objects boot parameter default value
  279. config DEBUG_SLAB
  280. bool "Debug slab memory allocations"
  281. depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
  282. help
  283. Say Y here to have the kernel do limited verification on memory
  284. allocation as well as poisoning memory on free to catch use of freed
  285. memory. This can make kmalloc/kfree-intensive workloads much slower.
  286. config DEBUG_SLAB_LEAK
  287. bool "Memory leak debugging"
  288. depends on DEBUG_SLAB
  289. config SLUB_DEBUG_ON
  290. bool "SLUB debugging on by default"
  291. depends on SLUB && SLUB_DEBUG && !KMEMCHECK
  292. default n
  293. help
  294. Boot with debugging on by default. SLUB boots by default with
  295. the runtime debug capabilities switched off. Enabling this is
  296. equivalent to specifying the "slub_debug" parameter on boot.
  297. There is no support for more fine grained debug control like
  298. possible with slub_debug=xxx. SLUB debugging may be switched
  299. off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
  300. "slub_debug=-".
  301. config SLUB_STATS
  302. default n
  303. bool "Enable SLUB performance statistics"
  304. depends on SLUB && SLUB_DEBUG && SYSFS
  305. help
  306. SLUB statistics are useful to debug SLUBs allocation behavior in
  307. order find ways to optimize the allocator. This should never be
  308. enabled for production use since keeping statistics slows down
  309. the allocator by a few percentage points. The slabinfo command
  310. supports the determination of the most active slabs to figure
  311. out which slabs are relevant to a particular load.
  312. Try running: slabinfo -DA
  313. config DEBUG_KMEMLEAK
  314. bool "Kernel memory leak detector"
  315. depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
  316. (X86 || ARM || PPC || S390)
  317. select DEBUG_FS if SYSFS
  318. select STACKTRACE if STACKTRACE_SUPPORT
  319. select KALLSYMS
  320. help
  321. Say Y here if you want to enable the memory leak
  322. detector. The memory allocation/freeing is traced in a way
  323. similar to the Boehm's conservative garbage collector, the
  324. difference being that the orphan objects are not freed but
  325. only shown in /sys/kernel/debug/kmemleak. Enabling this
  326. feature will introduce an overhead to memory
  327. allocations. See Documentation/kmemleak.txt for more
  328. details.
  329. Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
  330. of finding leaks due to the slab objects poisoning.
  331. In order to access the kmemleak file, debugfs needs to be
  332. mounted (usually at /sys/kernel/debug).
  333. config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
  334. int "Maximum kmemleak early log entries"
  335. depends on DEBUG_KMEMLEAK
  336. range 200 40000
  337. default 400
  338. help
  339. Kmemleak must track all the memory allocations to avoid
  340. reporting false positives. Since memory may be allocated or
  341. freed before kmemleak is initialised, an early log buffer is
  342. used to store these actions. If kmemleak reports "early log
  343. buffer exceeded", please increase this value.
  344. config DEBUG_KMEMLEAK_TEST
  345. tristate "Simple test for the kernel memory leak detector"
  346. depends on DEBUG_KMEMLEAK
  347. help
  348. Say Y or M here to build a test for the kernel memory leak
  349. detector. This option enables a module that explicitly leaks
  350. memory.
  351. If unsure, say N.
  352. config DEBUG_PREEMPT
  353. bool "Debug preemptible kernel"
  354. depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
  355. default y
  356. help
  357. If you say Y here then the kernel will use a debug variant of the
  358. commonly used smp_processor_id() function and will print warnings
  359. if kernel code uses it in a preemption-unsafe way. Also, the kernel
  360. will detect preemption count underflows.
  361. config DEBUG_RT_MUTEXES
  362. bool "RT Mutex debugging, deadlock detection"
  363. depends on DEBUG_KERNEL && RT_MUTEXES
  364. help
  365. This allows rt mutex semantics violations and rt mutex related
  366. deadlocks (lockups) to be detected and reported automatically.
  367. config DEBUG_PI_LIST
  368. bool
  369. default y
  370. depends on DEBUG_RT_MUTEXES
  371. config RT_MUTEX_TESTER
  372. bool "Built-in scriptable tester for rt-mutexes"
  373. depends on DEBUG_KERNEL && RT_MUTEXES
  374. help
  375. This option enables a rt-mutex tester.
  376. config DEBUG_SPINLOCK
  377. bool "Spinlock and rw-lock debugging: basic checks"
  378. depends on DEBUG_KERNEL
  379. help
  380. Say Y here and build SMP to catch missing spinlock initialization
  381. and certain other kinds of spinlock errors commonly made. This is
  382. best used in conjunction with the NMI watchdog so that spinlock
  383. deadlocks are also debuggable.
  384. config DEBUG_MUTEXES
  385. bool "Mutex debugging: basic checks"
  386. depends on DEBUG_KERNEL
  387. help
  388. This feature allows mutex semantics violations to be detected and
  389. reported.
  390. config DEBUG_LOCK_ALLOC
  391. bool "Lock debugging: detect incorrect freeing of live locks"
  392. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  393. select DEBUG_SPINLOCK
  394. select DEBUG_MUTEXES
  395. select LOCKDEP
  396. help
  397. This feature will check whether any held lock (spinlock, rwlock,
  398. mutex or rwsem) is incorrectly freed by the kernel, via any of the
  399. memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
  400. vfree(), etc.), whether a live lock is incorrectly reinitialized via
  401. spin_lock_init()/mutex_init()/etc., or whether there is any lock
  402. held during task exit.
  403. config PROVE_LOCKING
  404. bool "Lock debugging: prove locking correctness"
  405. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  406. select LOCKDEP
  407. select DEBUG_SPINLOCK
  408. select DEBUG_MUTEXES
  409. select DEBUG_LOCK_ALLOC
  410. default n
  411. help
  412. This feature enables the kernel to prove that all locking
  413. that occurs in the kernel runtime is mathematically
  414. correct: that under no circumstance could an arbitrary (and
  415. not yet triggered) combination of observed locking
  416. sequences (on an arbitrary number of CPUs, running an
  417. arbitrary number of tasks and interrupt contexts) cause a
  418. deadlock.
  419. In short, this feature enables the kernel to report locking
  420. related deadlocks before they actually occur.
  421. The proof does not depend on how hard and complex a
  422. deadlock scenario would be to trigger: how many
  423. participant CPUs, tasks and irq-contexts would be needed
  424. for it to trigger. The proof also does not depend on
  425. timing: if a race and a resulting deadlock is possible
  426. theoretically (no matter how unlikely the race scenario
  427. is), it will be proven so and will immediately be
  428. reported by the kernel (once the event is observed that
  429. makes the deadlock theoretically possible).
  430. If a deadlock is impossible (i.e. the locking rules, as
  431. observed by the kernel, are mathematically correct), the
  432. kernel reports nothing.
  433. NOTE: this feature can also be enabled for rwlocks, mutexes
  434. and rwsems - in which case all dependencies between these
  435. different locking variants are observed and mapped too, and
  436. the proof of observed correctness is also maintained for an
  437. arbitrary combination of these separate locking variants.
  438. For more details, see Documentation/lockdep-design.txt.
  439. config LOCKDEP
  440. bool
  441. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  442. select STACKTRACE
  443. select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
  444. select KALLSYMS
  445. select KALLSYMS_ALL
  446. config LOCK_STAT
  447. bool "Lock usage statistics"
  448. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  449. select LOCKDEP
  450. select DEBUG_SPINLOCK
  451. select DEBUG_MUTEXES
  452. select DEBUG_LOCK_ALLOC
  453. default n
  454. help
  455. This feature enables tracking lock contention points
  456. For more details, see Documentation/lockstat.txt
  457. config DEBUG_LOCKDEP
  458. bool "Lock dependency engine debugging"
  459. depends on DEBUG_KERNEL && LOCKDEP
  460. help
  461. If you say Y here, the lock dependency engine will do
  462. additional runtime checks to debug itself, at the price
  463. of more runtime overhead.
  464. config TRACE_IRQFLAGS
  465. depends on DEBUG_KERNEL
  466. bool
  467. default y
  468. depends on TRACE_IRQFLAGS_SUPPORT
  469. depends on PROVE_LOCKING
  470. config DEBUG_SPINLOCK_SLEEP
  471. bool "Spinlock debugging: sleep-inside-spinlock checking"
  472. depends on DEBUG_KERNEL
  473. help
  474. If you say Y here, various routines which may sleep will become very
  475. noisy if they are called with a spinlock held.
  476. config DEBUG_LOCKING_API_SELFTESTS
  477. bool "Locking API boot-time self-tests"
  478. depends on DEBUG_KERNEL
  479. help
  480. Say Y here if you want the kernel to run a short self-test during
  481. bootup. The self-test checks whether common types of locking bugs
  482. are detected by debugging mechanisms or not. (if you disable
  483. lock debugging then those bugs wont be detected of course.)
  484. The following locking APIs are covered: spinlocks, rwlocks,
  485. mutexes and rwsems.
  486. config STACKTRACE
  487. bool
  488. depends on STACKTRACE_SUPPORT
  489. config DEBUG_KOBJECT
  490. bool "kobject debugging"
  491. depends on DEBUG_KERNEL
  492. help
  493. If you say Y here, some extra kobject debugging messages will be sent
  494. to the syslog.
  495. config DEBUG_HIGHMEM
  496. bool "Highmem debugging"
  497. depends on DEBUG_KERNEL && HIGHMEM
  498. help
  499. This options enables addition error checking for high memory systems.
  500. Disable for production systems.
  501. config DEBUG_BUGVERBOSE
  502. bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
  503. depends on BUG
  504. depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
  505. FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
  506. default !EMBEDDED
  507. help
  508. Say Y here to make BUG() panics output the file name and line number
  509. of the BUG call as well as the EIP and oops trace. This aids
  510. debugging but costs about 70-100K of memory.
  511. config DEBUG_INFO
  512. bool "Compile the kernel with debug info"
  513. depends on DEBUG_KERNEL
  514. help
  515. If you say Y here the resulting kernel image will include
  516. debugging info resulting in a larger kernel image.
  517. This adds debug symbols to the kernel and modules (gcc -g), and
  518. is needed if you intend to use kernel crashdump or binary object
  519. tools like crash, kgdb, LKCD, gdb, etc on the kernel.
  520. Say Y here only if you plan to debug the kernel.
  521. If unsure, say N.
  522. config DEBUG_VM
  523. bool "Debug VM"
  524. depends on DEBUG_KERNEL
  525. help
  526. Enable this to turn on extended checks in the virtual-memory system
  527. that may impact performance.
  528. If unsure, say N.
  529. config DEBUG_VIRTUAL
  530. bool "Debug VM translations"
  531. depends on DEBUG_KERNEL && X86
  532. help
  533. Enable some costly sanity checks in virtual to page code. This can
  534. catch mistakes with virt_to_page() and friends.
  535. If unsure, say N.
  536. config DEBUG_NOMMU_REGIONS
  537. bool "Debug the global anon/private NOMMU mapping region tree"
  538. depends on DEBUG_KERNEL && !MMU
  539. help
  540. This option causes the global tree of anonymous and private mapping
  541. regions to be regularly checked for invalid topology.
  542. config DEBUG_WRITECOUNT
  543. bool "Debug filesystem writers count"
  544. depends on DEBUG_KERNEL
  545. help
  546. Enable this to catch wrong use of the writers count in struct
  547. vfsmount. This will increase the size of each file struct by
  548. 32 bits.
  549. If unsure, say N.
  550. config DEBUG_MEMORY_INIT
  551. bool "Debug memory initialisation" if EMBEDDED
  552. default !EMBEDDED
  553. help
  554. Enable this for additional checks during memory initialisation.
  555. The sanity checks verify aspects of the VM such as the memory model
  556. and other information provided by the architecture. Verbose
  557. information will be printed at KERN_DEBUG loglevel depending
  558. on the mminit_loglevel= command-line option.
  559. If unsure, say Y
  560. config DEBUG_LIST
  561. bool "Debug linked list manipulation"
  562. depends on DEBUG_KERNEL
  563. help
  564. Enable this to turn on extended checks in the linked-list
  565. walking routines.
  566. If unsure, say N.
  567. config DEBUG_SG
  568. bool "Debug SG table operations"
  569. depends on DEBUG_KERNEL
  570. help
  571. Enable this to turn on checks on scatter-gather tables. This can
  572. help find problems with drivers that do not properly initialize
  573. their sg tables.
  574. If unsure, say N.
  575. config DEBUG_NOTIFIERS
  576. bool "Debug notifier call chains"
  577. depends on DEBUG_KERNEL
  578. help
  579. Enable this to turn on sanity checking for notifier call chains.
  580. This is most useful for kernel developers to make sure that
  581. modules properly unregister themselves from notifier chains.
  582. This is a relatively cheap check but if you care about maximum
  583. performance, say N.
  584. config DEBUG_CREDENTIALS
  585. bool "Debug credential management"
  586. depends on DEBUG_KERNEL
  587. help
  588. Enable this to turn on some debug checking for credential
  589. management. The additional code keeps track of the number of
  590. pointers from task_structs to any given cred struct, and checks to
  591. see that this number never exceeds the usage count of the cred
  592. struct.
  593. Furthermore, if SELinux is enabled, this also checks that the
  594. security pointer in the cred struct is never seen to be invalid.
  595. If unsure, say N.
  596. #
  597. # Select this config option from the architecture Kconfig, if it
  598. # it is preferred to always offer frame pointers as a config
  599. # option on the architecture (regardless of KERNEL_DEBUG):
  600. #
  601. config ARCH_WANT_FRAME_POINTERS
  602. bool
  603. help
  604. config FRAME_POINTER
  605. bool "Compile the kernel with frame pointers"
  606. depends on DEBUG_KERNEL && \
  607. (CRIS || M68K || M68KNOMMU || FRV || UML || \
  608. AVR32 || SUPERH || BLACKFIN || MN10300) || \
  609. ARCH_WANT_FRAME_POINTERS
  610. default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
  611. help
  612. If you say Y here the resulting kernel image will be slightly
  613. larger and slower, but it gives very useful debugging information
  614. in case of kernel bugs. (precise oopses/stacktraces/warnings)
  615. config BOOT_PRINTK_DELAY
  616. bool "Delay each boot printk message by N milliseconds"
  617. depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
  618. help
  619. This build option allows you to read kernel boot messages
  620. by inserting a short delay after each one. The delay is
  621. specified in milliseconds on the kernel command line,
  622. using "boot_delay=N".
  623. It is likely that you would also need to use "lpj=M" to preset
  624. the "loops per jiffie" value.
  625. See a previous boot log for the "lpj" value to use for your
  626. system, and then set "lpj=M" before setting "boot_delay=N".
  627. NOTE: Using this option may adversely affect SMP systems.
  628. I.e., processors other than the first one may not boot up.
  629. BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
  630. what it believes to be lockup conditions.
  631. config RCU_TORTURE_TEST
  632. tristate "torture tests for RCU"
  633. depends on DEBUG_KERNEL
  634. default n
  635. help
  636. This option provides a kernel module that runs torture tests
  637. on the RCU infrastructure. The kernel module may be built
  638. after the fact on the running kernel to be tested, if desired.
  639. Say Y here if you want RCU torture tests to be built into
  640. the kernel.
  641. Say M if you want the RCU torture tests to build as a module.
  642. Say N if you are unsure.
  643. config RCU_TORTURE_TEST_RUNNABLE
  644. bool "torture tests for RCU runnable by default"
  645. depends on RCU_TORTURE_TEST = y
  646. default n
  647. help
  648. This option provides a way to build the RCU torture tests
  649. directly into the kernel without them starting up at boot
  650. time. You can use /proc/sys/kernel/rcutorture_runnable
  651. to manually override this setting. This /proc file is
  652. available only when the RCU torture tests have been built
  653. into the kernel.
  654. Say Y here if you want the RCU torture tests to start during
  655. boot (you probably don't).
  656. Say N here if you want the RCU torture tests to start only
  657. after being manually enabled via /proc.
  658. config RCU_CPU_STALL_DETECTOR
  659. bool "Check for stalled CPUs delaying RCU grace periods"
  660. depends on TREE_RCU || TREE_PREEMPT_RCU
  661. default y
  662. help
  663. This option causes RCU to printk information on which
  664. CPUs are delaying the current grace period, but only when
  665. the grace period extends for excessive time periods.
  666. Say Y if you want RCU to perform such checks.
  667. Say N if you are unsure.
  668. config KPROBES_SANITY_TEST
  669. bool "Kprobes sanity tests"
  670. depends on DEBUG_KERNEL
  671. depends on KPROBES
  672. default n
  673. help
  674. This option provides for testing basic kprobes functionality on
  675. boot. A sample kprobe, jprobe and kretprobe are inserted and
  676. verified for functionality.
  677. Say N if you are unsure.
  678. config BACKTRACE_SELF_TEST
  679. tristate "Self test for the backtrace code"
  680. depends on DEBUG_KERNEL
  681. default n
  682. help
  683. This option provides a kernel module that can be used to test
  684. the kernel stack backtrace code. This option is not useful
  685. for distributions or general kernels, but only for kernel
  686. developers working on architecture code.
  687. Note that if you want to also test saved backtraces, you will
  688. have to enable STACKTRACE as well.
  689. Say N if you are unsure.
  690. config DEBUG_BLOCK_EXT_DEVT
  691. bool "Force extended block device numbers and spread them"
  692. depends on DEBUG_KERNEL
  693. depends on BLOCK
  694. default n
  695. help
  696. BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
  697. SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
  698. YOU ARE DOING. Distros, please enable this and fix whatever
  699. is broken.
  700. Conventionally, block device numbers are allocated from
  701. predetermined contiguous area. However, extended block area
  702. may introduce non-contiguous block device numbers. This
  703. option forces most block device numbers to be allocated from
  704. the extended space and spreads them to discover kernel or
  705. userland code paths which assume predetermined contiguous
  706. device number allocation.
  707. Note that turning on this debug option shuffles all the
  708. device numbers for all IDE and SCSI devices including libata
  709. ones, so root partition specified using device number
  710. directly (via rdev or root=MAJ:MIN) won't work anymore.
  711. Textual device names (root=/dev/sdXn) will continue to work.
  712. Say N if you are unsure.
  713. config DEBUG_FORCE_WEAK_PER_CPU
  714. bool "Force weak per-cpu definitions"
  715. depends on DEBUG_KERNEL
  716. help
  717. s390 and alpha require percpu variables in modules to be
  718. defined weak to work around addressing range issue which
  719. puts the following two restrictions on percpu variable
  720. definitions.
  721. 1. percpu symbols must be unique whether static or not
  722. 2. percpu variables can't be defined inside a function
  723. To ensure that generic code follows the above rules, this
  724. option forces all percpu variables to be defined as weak.
  725. config LKDTM
  726. tristate "Linux Kernel Dump Test Tool Module"
  727. depends on DEBUG_KERNEL
  728. depends on KPROBES
  729. depends on BLOCK
  730. default n
  731. help
  732. This module enables testing of the different dumping mechanisms by
  733. inducing system failures at predefined crash points.
  734. If you don't need it: say N
  735. Choose M here to compile this code as a module. The module will be
  736. called lkdtm.
  737. Documentation on how to use the module can be found in
  738. drivers/misc/lkdtm.c
  739. config FAULT_INJECTION
  740. bool "Fault-injection framework"
  741. depends on DEBUG_KERNEL
  742. help
  743. Provide fault-injection framework.
  744. For more details, see Documentation/fault-injection/.
  745. config FAILSLAB
  746. bool "Fault-injection capability for kmalloc"
  747. depends on FAULT_INJECTION
  748. depends on SLAB || SLUB
  749. help
  750. Provide fault-injection capability for kmalloc.
  751. config FAIL_PAGE_ALLOC
  752. bool "Fault-injection capabilitiy for alloc_pages()"
  753. depends on FAULT_INJECTION
  754. help
  755. Provide fault-injection capability for alloc_pages().
  756. config FAIL_MAKE_REQUEST
  757. bool "Fault-injection capability for disk IO"
  758. depends on FAULT_INJECTION && BLOCK
  759. help
  760. Provide fault-injection capability for disk IO.
  761. config FAIL_IO_TIMEOUT
  762. bool "Faul-injection capability for faking disk interrupts"
  763. depends on FAULT_INJECTION && BLOCK
  764. help
  765. Provide fault-injection capability on end IO handling. This
  766. will make the block layer "forget" an interrupt as configured,
  767. thus exercising the error handling.
  768. Only works with drivers that use the generic timeout handling,
  769. for others it wont do anything.
  770. config FAULT_INJECTION_DEBUG_FS
  771. bool "Debugfs entries for fault-injection capabilities"
  772. depends on FAULT_INJECTION && SYSFS && DEBUG_FS
  773. help
  774. Enable configuration of fault-injection capabilities via debugfs.
  775. config FAULT_INJECTION_STACKTRACE_FILTER
  776. bool "stacktrace filter for fault-injection capabilities"
  777. depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
  778. depends on !X86_64
  779. select STACKTRACE
  780. select FRAME_POINTER if !PPC && !S390
  781. help
  782. Provide stacktrace filter for fault-injection capabilities
  783. config LATENCYTOP
  784. bool "Latency measuring infrastructure"
  785. select FRAME_POINTER if !MIPS && !PPC && !S390
  786. select KALLSYMS
  787. select KALLSYMS_ALL
  788. select STACKTRACE
  789. select SCHEDSTATS
  790. select SCHED_DEBUG
  791. depends on HAVE_LATENCYTOP_SUPPORT
  792. help
  793. Enable this option if you want to use the LatencyTOP tool
  794. to find out which userspace is blocking on what kernel operations.
  795. config SYSCTL_SYSCALL_CHECK
  796. bool "Sysctl checks"
  797. depends on SYSCTL
  798. ---help---
  799. sys_sysctl uses binary paths that have been found challenging
  800. to properly maintain and use. This enables checks that help
  801. you to keep things correct.
  802. source mm/Kconfig.debug
  803. source kernel/trace/Kconfig
  804. config PROVIDE_OHCI1394_DMA_INIT
  805. bool "Remote debugging over FireWire early on boot"
  806. depends on PCI && X86
  807. help
  808. If you want to debug problems which hang or crash the kernel early
  809. on boot and the crashing machine has a FireWire port, you can use
  810. this feature to remotely access the memory of the crashed machine
  811. over FireWire. This employs remote DMA as part of the OHCI1394
  812. specification which is now the standard for FireWire controllers.
  813. With remote DMA, you can monitor the printk buffer remotely using
  814. firescope and access all memory below 4GB using fireproxy from gdb.
  815. Even controlling a kernel debugger is possible using remote DMA.
  816. Usage:
  817. If ohci1394_dma=early is used as boot parameter, it will initialize
  818. all OHCI1394 controllers which are found in the PCI config space.
  819. As all changes to the FireWire bus such as enabling and disabling
  820. devices cause a bus reset and thereby disable remote DMA for all
  821. devices, be sure to have the cable plugged and FireWire enabled on
  822. the debugging host before booting the debug target for debugging.
  823. This code (~1k) is freed after boot. By then, the firewire stack
  824. in charge of the OHCI-1394 controllers should be used instead.
  825. See Documentation/debugging-via-ohci1394.txt for more information.
  826. config FIREWIRE_OHCI_REMOTE_DMA
  827. bool "Remote debugging over FireWire with firewire-ohci"
  828. depends on FIREWIRE_OHCI
  829. help
  830. This option lets you use the FireWire bus for remote debugging
  831. with help of the firewire-ohci driver. It enables unfiltered
  832. remote DMA in firewire-ohci.
  833. See Documentation/debugging-via-ohci1394.txt for more information.
  834. If unsure, say N.
  835. config BUILD_DOCSRC
  836. bool "Build targets in Documentation/ tree"
  837. depends on HEADERS_CHECK
  838. help
  839. This option attempts to build objects from the source files in the
  840. kernel Documentation/ tree.
  841. Say N if you are unsure.
  842. config DYNAMIC_DEBUG
  843. bool "Enable dynamic printk() support"
  844. default n
  845. depends on PRINTK
  846. depends on DEBUG_FS
  847. help
  848. Compiles debug level messages into the kernel, which would not
  849. otherwise be available at runtime. These messages can then be
  850. enabled/disabled based on various levels of scope - per source file,
  851. function, module, format string, and line number. This mechanism
  852. implicitly enables all pr_debug() and dev_dbg() calls. The impact of
  853. this compile option is a larger kernel text size of about 2%.
  854. Usage:
  855. Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
  856. which is contained in the 'debugfs' filesystem. Thus, the debugfs
  857. filesystem must first be mounted before making use of this feature.
  858. We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
  859. file contains a list of the debug statements that can be enabled. The
  860. format for each line of the file is:
  861. filename:lineno [module]function flags format
  862. filename : source file of the debug statement
  863. lineno : line number of the debug statement
  864. module : module that contains the debug statement
  865. function : function that contains the debug statement
  866. flags : 'p' means the line is turned 'on' for printing
  867. format : the format used for the debug statement
  868. From a live system:
  869. nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
  870. # filename:lineno [module]function flags format
  871. fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
  872. fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
  873. fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
  874. Example usage:
  875. // enable the message at line 1603 of file svcsock.c
  876. nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
  877. <debugfs>/dynamic_debug/ddebug
  878. // enable all the messages in file svcsock.c
  879. nullarbor:~ # echo -n 'file svcsock.c +p' >
  880. <debugfs>/dynamic_debug/ddebug
  881. // enable all the messages in the NFS server module
  882. nullarbor:~ # echo -n 'module nfsd +p' >
  883. <debugfs>/dynamic_debug/ddebug
  884. // enable all 12 messages in the function svc_process()
  885. nullarbor:~ # echo -n 'func svc_process +p' >
  886. <debugfs>/dynamic_debug/ddebug
  887. // disable all 12 messages in the function svc_process()
  888. nullarbor:~ # echo -n 'func svc_process -p' >
  889. <debugfs>/dynamic_debug/ddebug
  890. See Documentation/dynamic-debug-howto.txt for additional information.
  891. config DMA_API_DEBUG
  892. bool "Enable debugging of DMA-API usage"
  893. depends on HAVE_DMA_API_DEBUG
  894. help
  895. Enable this option to debug the use of the DMA API by device drivers.
  896. With this option you will be able to detect common bugs in device
  897. drivers like double-freeing of DMA mappings or freeing mappings that
  898. were never allocated.
  899. This option causes a performance degredation. Use only if you want
  900. to debug device drivers. If unsure, say N.
  901. source "samples/Kconfig"
  902. source "lib/Kconfig.kgdb"
  903. source "lib/Kconfig.kmemcheck"