Kconfig.debug 16 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_MUST_CHECK
  11. bool "Enable __must_check logic"
  12. default y
  13. help
  14. Enable the __must_check logic in the kernel build. Disable this to
  15. suppress the "warning: ignoring return value of 'foo', declared with
  16. attribute warn_unused_result" messages.
  17. config MAGIC_SYSRQ
  18. bool "Magic SysRq key"
  19. depends on !UML
  20. help
  21. If you say Y here, you will have some control over the system even
  22. if the system crashes for example during kernel debugging (e.g., you
  23. will be able to flush the buffer cache to disk, reboot the system
  24. immediately or dump some status information). This is accomplished
  25. by pressing various keys while holding SysRq (Alt+PrintScreen). It
  26. also works on a serial console (on PC hardware at least), if you
  27. send a BREAK and then within 5 seconds a command keypress. The
  28. keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  29. unless you really know what this hack does.
  30. config UNUSED_SYMBOLS
  31. bool "Enable unused/obsolete exported symbols"
  32. default y if X86
  33. help
  34. Unused but exported symbols make the kernel needlessly bigger. For
  35. that reason most of these unused exports will soon be removed. This
  36. option is provided temporarily to provide a transition period in case
  37. some external kernel module needs one of these symbols anyway. If you
  38. encounter such a case in your module, consider if you are actually
  39. using the right API. (rationale: since nobody in the kernel is using
  40. this in a module, there is a pretty good chance it's actually the
  41. wrong interface to use). If you really need the symbol, please send a
  42. mail to the linux kernel mailing list mentioning the symbol and why
  43. you really need it, and what the merge plan to the mainline kernel for
  44. your module is.
  45. config DEBUG_FS
  46. bool "Debug Filesystem"
  47. depends on SYSFS
  48. help
  49. debugfs is a virtual file system that kernel developers use to put
  50. debugging files into. Enable this option to be able to read and
  51. write to these files.
  52. If unsure, say N.
  53. config HEADERS_CHECK
  54. bool "Run 'make headers_check' when building vmlinux"
  55. depends on !UML
  56. help
  57. This option will extract the user-visible kernel headers whenever
  58. building the kernel, and will run basic sanity checks on them to
  59. ensure that exported files do not attempt to include files which
  60. were not exported, etc.
  61. If you're making modifications to header files which are
  62. relevant for userspace, say 'Y', and check the headers
  63. exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  64. your build tree), to make sure they're suitable.
  65. config DEBUG_KERNEL
  66. bool "Kernel debugging"
  67. help
  68. Say Y here if you are developing drivers or trying to debug and
  69. identify kernel problems.
  70. config DEBUG_SHIRQ
  71. bool "Debug shared IRQ handlers"
  72. depends on DEBUG_KERNEL && GENERIC_HARDIRQS
  73. help
  74. Enable this to generate a spurious interrupt as soon as a shared
  75. interrupt handler is registered, and just before one is deregistered.
  76. Drivers ought to be able to handle interrupts coming in at those
  77. points; some don't and need to be caught.
  78. config LOG_BUF_SHIFT
  79. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
  80. range 12 21
  81. default 17 if S390 || LOCKDEP
  82. default 16 if X86_NUMAQ || IA64
  83. default 15 if SMP
  84. default 14
  85. help
  86. Select kernel log buffer size as a power of 2.
  87. Defaults and Examples:
  88. 17 => 128 KB for S/390
  89. 16 => 64 KB for x86 NUMAQ or IA-64
  90. 15 => 32 KB for SMP
  91. 14 => 16 KB for uniprocessor
  92. 13 => 8 KB
  93. 12 => 4 KB
  94. config DETECT_SOFTLOCKUP
  95. bool "Detect Soft Lockups"
  96. depends on DEBUG_KERNEL && !S390
  97. default y
  98. help
  99. Say Y here to enable the kernel to detect "soft lockups",
  100. which are bugs that cause the kernel to loop in kernel
  101. mode for more than 10 seconds, without giving other tasks a
  102. chance to run.
  103. When a soft-lockup is detected, the kernel will print the
  104. current stack trace (which you should report), but the
  105. system will stay locked up. This feature has negligible
  106. overhead.
  107. (Note that "hard lockups" are separate type of bugs that
  108. can be detected via the NMI-watchdog, on platforms that
  109. support it.)
  110. config SCHED_DEBUG
  111. bool "Collect scheduler debugging info"
  112. depends on DEBUG_KERNEL && PROC_FS
  113. default y
  114. help
  115. If you say Y here, the /proc/sched_debug file will be provided
  116. that can help debug the scheduler. The runtime overhead of this
  117. option is minimal.
  118. config SCHEDSTATS
  119. bool "Collect scheduler statistics"
  120. depends on DEBUG_KERNEL && PROC_FS
  121. help
  122. If you say Y here, additional code will be inserted into the
  123. scheduler and related routines to collect statistics about
  124. scheduler behavior and provide them in /proc/schedstat. These
  125. stats may be useful for both tuning and debugging the scheduler
  126. If you aren't debugging the scheduler or trying to tune a specific
  127. application, you can say N to avoid the very slight overhead
  128. this adds.
  129. config TIMER_STATS
  130. bool "Collect kernel timers statistics"
  131. depends on DEBUG_KERNEL && PROC_FS
  132. help
  133. If you say Y here, additional code will be inserted into the
  134. timer routines to collect statistics about kernel timers being
  135. reprogrammed. The statistics can be read from /proc/timer_stats.
  136. The statistics collection is started by writing 1 to /proc/timer_stats,
  137. writing 0 stops it. This feature is useful to collect information
  138. about timer usage patterns in kernel and userspace. This feature
  139. is lightweight if enabled in the kernel config but not activated
  140. (it defaults to deactivated on bootup and will only be activated
  141. if some application like powertop activates it explicitly).
  142. config DEBUG_SLAB
  143. bool "Debug slab memory allocations"
  144. depends on DEBUG_KERNEL && SLAB
  145. help
  146. Say Y here to have the kernel do limited verification on memory
  147. allocation as well as poisoning memory on free to catch use of freed
  148. memory. This can make kmalloc/kfree-intensive workloads much slower.
  149. config DEBUG_SLAB_LEAK
  150. bool "Memory leak debugging"
  151. depends on DEBUG_SLAB
  152. config DEBUG_PREEMPT
  153. bool "Debug preemptible kernel"
  154. depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
  155. default y
  156. help
  157. If you say Y here then the kernel will use a debug variant of the
  158. commonly used smp_processor_id() function and will print warnings
  159. if kernel code uses it in a preemption-unsafe way. Also, the kernel
  160. will detect preemption count underflows.
  161. config DEBUG_RT_MUTEXES
  162. bool "RT Mutex debugging, deadlock detection"
  163. depends on DEBUG_KERNEL && RT_MUTEXES
  164. help
  165. This allows rt mutex semantics violations and rt mutex related
  166. deadlocks (lockups) to be detected and reported automatically.
  167. config DEBUG_PI_LIST
  168. bool
  169. default y
  170. depends on DEBUG_RT_MUTEXES
  171. config RT_MUTEX_TESTER
  172. bool "Built-in scriptable tester for rt-mutexes"
  173. depends on DEBUG_KERNEL && RT_MUTEXES
  174. help
  175. This option enables a rt-mutex tester.
  176. config DEBUG_SPINLOCK
  177. bool "Spinlock and rw-lock debugging: basic checks"
  178. depends on DEBUG_KERNEL
  179. help
  180. Say Y here and build SMP to catch missing spinlock initialization
  181. and certain other kinds of spinlock errors commonly made. This is
  182. best used in conjunction with the NMI watchdog so that spinlock
  183. deadlocks are also debuggable.
  184. config DEBUG_MUTEXES
  185. bool "Mutex debugging: basic checks"
  186. depends on DEBUG_KERNEL
  187. help
  188. This feature allows mutex semantics violations to be detected and
  189. reported.
  190. config DEBUG_LOCK_ALLOC
  191. bool "Lock debugging: detect incorrect freeing of live locks"
  192. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  193. select DEBUG_SPINLOCK
  194. select DEBUG_MUTEXES
  195. select LOCKDEP
  196. help
  197. This feature will check whether any held lock (spinlock, rwlock,
  198. mutex or rwsem) is incorrectly freed by the kernel, via any of the
  199. memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
  200. vfree(), etc.), whether a live lock is incorrectly reinitialized via
  201. spin_lock_init()/mutex_init()/etc., or whether there is any lock
  202. held during task exit.
  203. config PROVE_LOCKING
  204. bool "Lock debugging: prove locking correctness"
  205. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  206. select LOCKDEP
  207. select DEBUG_SPINLOCK
  208. select DEBUG_MUTEXES
  209. select DEBUG_LOCK_ALLOC
  210. default n
  211. help
  212. This feature enables the kernel to prove that all locking
  213. that occurs in the kernel runtime is mathematically
  214. correct: that under no circumstance could an arbitrary (and
  215. not yet triggered) combination of observed locking
  216. sequences (on an arbitrary number of CPUs, running an
  217. arbitrary number of tasks and interrupt contexts) cause a
  218. deadlock.
  219. In short, this feature enables the kernel to report locking
  220. related deadlocks before they actually occur.
  221. The proof does not depend on how hard and complex a
  222. deadlock scenario would be to trigger: how many
  223. participant CPUs, tasks and irq-contexts would be needed
  224. for it to trigger. The proof also does not depend on
  225. timing: if a race and a resulting deadlock is possible
  226. theoretically (no matter how unlikely the race scenario
  227. is), it will be proven so and will immediately be
  228. reported by the kernel (once the event is observed that
  229. makes the deadlock theoretically possible).
  230. If a deadlock is impossible (i.e. the locking rules, as
  231. observed by the kernel, are mathematically correct), the
  232. kernel reports nothing.
  233. NOTE: this feature can also be enabled for rwlocks, mutexes
  234. and rwsems - in which case all dependencies between these
  235. different locking variants are observed and mapped too, and
  236. the proof of observed correctness is also maintained for an
  237. arbitrary combination of these separate locking variants.
  238. For more details, see Documentation/lockdep-design.txt.
  239. config LOCKDEP
  240. bool
  241. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  242. select STACKTRACE
  243. select FRAME_POINTER if !X86
  244. select KALLSYMS
  245. select KALLSYMS_ALL
  246. config DEBUG_LOCKDEP
  247. bool "Lock dependency engine debugging"
  248. depends on DEBUG_KERNEL && LOCKDEP
  249. help
  250. If you say Y here, the lock dependency engine will do
  251. additional runtime checks to debug itself, at the price
  252. of more runtime overhead.
  253. config TRACE_IRQFLAGS
  254. depends on DEBUG_KERNEL
  255. bool
  256. default y
  257. depends on TRACE_IRQFLAGS_SUPPORT
  258. depends on PROVE_LOCKING
  259. config DEBUG_SPINLOCK_SLEEP
  260. bool "Spinlock debugging: sleep-inside-spinlock checking"
  261. depends on DEBUG_KERNEL
  262. help
  263. If you say Y here, various routines which may sleep will become very
  264. noisy if they are called with a spinlock held.
  265. config DEBUG_LOCKING_API_SELFTESTS
  266. bool "Locking API boot-time self-tests"
  267. depends on DEBUG_KERNEL
  268. help
  269. Say Y here if you want the kernel to run a short self-test during
  270. bootup. The self-test checks whether common types of locking bugs
  271. are detected by debugging mechanisms or not. (if you disable
  272. lock debugging then those bugs wont be detected of course.)
  273. The following locking APIs are covered: spinlocks, rwlocks,
  274. mutexes and rwsems.
  275. config STACKTRACE
  276. bool
  277. depends on DEBUG_KERNEL
  278. depends on STACKTRACE_SUPPORT
  279. config DEBUG_KOBJECT
  280. bool "kobject debugging"
  281. depends on DEBUG_KERNEL
  282. help
  283. If you say Y here, some extra kobject debugging messages will be sent
  284. to the syslog.
  285. config DEBUG_HIGHMEM
  286. bool "Highmem debugging"
  287. depends on DEBUG_KERNEL && HIGHMEM
  288. help
  289. This options enables addition error checking for high memory systems.
  290. Disable for production systems.
  291. config DEBUG_BUGVERBOSE
  292. bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
  293. depends on BUG
  294. depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || FRV || SUPERH || GENERIC_BUG
  295. default !EMBEDDED
  296. help
  297. Say Y here to make BUG() panics output the file name and line number
  298. of the BUG call as well as the EIP and oops trace. This aids
  299. debugging but costs about 70-100K of memory.
  300. config DEBUG_INFO
  301. bool "Compile the kernel with debug info"
  302. depends on DEBUG_KERNEL
  303. help
  304. If you say Y here the resulting kernel image will include
  305. debugging info resulting in a larger kernel image.
  306. Say Y here only if you plan to debug the kernel.
  307. If unsure, say N.
  308. config DEBUG_VM
  309. bool "Debug VM"
  310. depends on DEBUG_KERNEL
  311. help
  312. Enable this to turn on extended checks in the virtual-memory system
  313. that may impact performance.
  314. If unsure, say N.
  315. config DEBUG_LIST
  316. bool "Debug linked list manipulation"
  317. depends on DEBUG_KERNEL
  318. help
  319. Enable this to turn on extended checks in the linked-list
  320. walking routines.
  321. If unsure, say N.
  322. config FRAME_POINTER
  323. bool "Compile the kernel with frame pointers"
  324. depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH)
  325. default y if DEBUG_INFO && UML
  326. help
  327. If you say Y here the resulting kernel image will be slightly larger
  328. and slower, but it might give very useful debugging information on
  329. some architectures or if you use external debuggers.
  330. If you don't debug the kernel, you can say N.
  331. config FORCED_INLINING
  332. bool "Force gcc to inline functions marked 'inline'"
  333. depends on DEBUG_KERNEL
  334. default y
  335. help
  336. This option determines if the kernel forces gcc to inline the functions
  337. developers have marked 'inline'. Doing so takes away freedom from gcc to
  338. do what it thinks is best, which is desirable for the gcc 3.x series of
  339. compilers. The gcc 4.x series have a rewritten inlining algorithm and
  340. disabling this option will generate a smaller kernel there. Hopefully
  341. this algorithm is so good that allowing gcc4 to make the decision can
  342. become the default in the future, until then this option is there to
  343. test gcc for this.
  344. config RCU_TORTURE_TEST
  345. tristate "torture tests for RCU"
  346. depends on DEBUG_KERNEL
  347. default n
  348. help
  349. This option provides a kernel module that runs torture tests
  350. on the RCU infrastructure. The kernel module may be built
  351. after the fact on the running kernel to be tested, if desired.
  352. Say Y here if you want RCU torture tests to start automatically
  353. at boot time (you probably don't).
  354. Say M if you want the RCU torture tests to build as a module.
  355. Say N if you are unsure.
  356. config LKDTM
  357. tristate "Linux Kernel Dump Test Tool Module"
  358. depends on DEBUG_KERNEL
  359. depends on KPROBES
  360. default n
  361. help
  362. This module enables testing of the different dumping mechanisms by
  363. inducing system failures at predefined crash points.
  364. If you don't need it: say N
  365. Choose M here to compile this code as a module. The module will be
  366. called lkdtm.
  367. Documentation on how to use the module can be found in
  368. drivers/misc/lkdtm.c
  369. config FAULT_INJECTION
  370. bool "Fault-injection framework"
  371. depends on DEBUG_KERNEL
  372. help
  373. Provide fault-injection framework.
  374. For more details, see Documentation/fault-injection/.
  375. config FAILSLAB
  376. bool "Fault-injection capability for kmalloc"
  377. depends on FAULT_INJECTION
  378. help
  379. Provide fault-injection capability for kmalloc.
  380. config FAIL_PAGE_ALLOC
  381. bool "Fault-injection capabilitiy for alloc_pages()"
  382. depends on FAULT_INJECTION
  383. help
  384. Provide fault-injection capability for alloc_pages().
  385. config FAIL_MAKE_REQUEST
  386. bool "Fault-injection capability for disk IO"
  387. depends on FAULT_INJECTION
  388. help
  389. Provide fault-injection capability for disk IO.
  390. config FAULT_INJECTION_DEBUG_FS
  391. bool "Debugfs entries for fault-injection capabilities"
  392. depends on FAULT_INJECTION && SYSFS && DEBUG_FS
  393. help
  394. Enable configuration of fault-injection capabilities via debugfs.
  395. config FAULT_INJECTION_STACKTRACE_FILTER
  396. bool "stacktrace filter for fault-injection capabilities"
  397. depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
  398. select STACKTRACE
  399. select FRAME_POINTER
  400. help
  401. Provide stacktrace filter for fault-injection capabilities