Kconfig.debug 14 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_KERNEL
  46. bool "Kernel debugging"
  47. help
  48. Say Y here if you are developing drivers or trying to debug and
  49. identify kernel problems.
  50. config LOG_BUF_SHIFT
  51. int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
  52. range 12 21
  53. default 17 if S390 || LOCKDEP
  54. default 16 if X86_NUMAQ || IA64
  55. default 15 if SMP
  56. default 14
  57. help
  58. Select kernel log buffer size as a power of 2.
  59. Defaults and Examples:
  60. 17 => 128 KB for S/390
  61. 16 => 64 KB for x86 NUMAQ or IA-64
  62. 15 => 32 KB for SMP
  63. 14 => 16 KB for uniprocessor
  64. 13 => 8 KB
  65. 12 => 4 KB
  66. config DETECT_SOFTLOCKUP
  67. bool "Detect Soft Lockups"
  68. depends on DEBUG_KERNEL && !S390
  69. default y
  70. help
  71. Say Y here to enable the kernel to detect "soft lockups",
  72. which are bugs that cause the kernel to loop in kernel
  73. mode for more than 10 seconds, without giving other tasks a
  74. chance to run.
  75. When a soft-lockup is detected, the kernel will print the
  76. current stack trace (which you should report), but the
  77. system will stay locked up. This feature has negligible
  78. overhead.
  79. (Note that "hard lockups" are separate type of bugs that
  80. can be detected via the NMI-watchdog, on platforms that
  81. support it.)
  82. config SCHEDSTATS
  83. bool "Collect scheduler statistics"
  84. depends on DEBUG_KERNEL && PROC_FS
  85. help
  86. If you say Y here, additional code will be inserted into the
  87. scheduler and related routines to collect statistics about
  88. scheduler behavior and provide them in /proc/schedstat. These
  89. stats may be useful for both tuning and debugging the scheduler
  90. If you aren't debugging the scheduler or trying to tune a specific
  91. application, you can say N to avoid the very slight overhead
  92. this adds.
  93. config DEBUG_SLAB
  94. bool "Debug slab memory allocations"
  95. depends on DEBUG_KERNEL && SLAB
  96. help
  97. Say Y here to have the kernel do limited verification on memory
  98. allocation as well as poisoning memory on free to catch use of freed
  99. memory. This can make kmalloc/kfree-intensive workloads much slower.
  100. config DEBUG_SLAB_LEAK
  101. bool "Memory leak debugging"
  102. depends on DEBUG_SLAB
  103. config DEBUG_PREEMPT
  104. bool "Debug preemptible kernel"
  105. depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
  106. default y
  107. help
  108. If you say Y here then the kernel will use a debug variant of the
  109. commonly used smp_processor_id() function and will print warnings
  110. if kernel code uses it in a preemption-unsafe way. Also, the kernel
  111. will detect preemption count underflows.
  112. config DEBUG_RT_MUTEXES
  113. bool "RT Mutex debugging, deadlock detection"
  114. depends on DEBUG_KERNEL && RT_MUTEXES
  115. help
  116. This allows rt mutex semantics violations and rt mutex related
  117. deadlocks (lockups) to be detected and reported automatically.
  118. config DEBUG_PI_LIST
  119. bool
  120. default y
  121. depends on DEBUG_RT_MUTEXES
  122. config RT_MUTEX_TESTER
  123. bool "Built-in scriptable tester for rt-mutexes"
  124. depends on DEBUG_KERNEL && RT_MUTEXES
  125. help
  126. This option enables a rt-mutex tester.
  127. config DEBUG_SPINLOCK
  128. bool "Spinlock and rw-lock debugging: basic checks"
  129. depends on DEBUG_KERNEL
  130. help
  131. Say Y here and build SMP to catch missing spinlock initialization
  132. and certain other kinds of spinlock errors commonly made. This is
  133. best used in conjunction with the NMI watchdog so that spinlock
  134. deadlocks are also debuggable.
  135. config DEBUG_MUTEXES
  136. bool "Mutex debugging: basic checks"
  137. depends on DEBUG_KERNEL
  138. help
  139. This feature allows mutex semantics violations to be detected and
  140. reported.
  141. config DEBUG_RWSEMS
  142. bool "RW-sem debugging: basic checks"
  143. depends on DEBUG_KERNEL
  144. help
  145. This feature allows read-write semaphore semantics violations to
  146. be detected and reported.
  147. config DEBUG_LOCK_ALLOC
  148. bool "Lock debugging: detect incorrect freeing of live locks"
  149. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  150. select DEBUG_SPINLOCK
  151. select DEBUG_MUTEXES
  152. select DEBUG_RWSEMS
  153. select LOCKDEP
  154. help
  155. This feature will check whether any held lock (spinlock, rwlock,
  156. mutex or rwsem) is incorrectly freed by the kernel, via any of the
  157. memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
  158. vfree(), etc.), whether a live lock is incorrectly reinitialized via
  159. spin_lock_init()/mutex_init()/etc., or whether there is any lock
  160. held during task exit.
  161. config PROVE_LOCKING
  162. bool "Lock debugging: prove locking correctness"
  163. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  164. select LOCKDEP
  165. select DEBUG_SPINLOCK
  166. select DEBUG_MUTEXES
  167. select DEBUG_RWSEMS
  168. select DEBUG_LOCK_ALLOC
  169. default n
  170. help
  171. This feature enables the kernel to prove that all locking
  172. that occurs in the kernel runtime is mathematically
  173. correct: that under no circumstance could an arbitrary (and
  174. not yet triggered) combination of observed locking
  175. sequences (on an arbitrary number of CPUs, running an
  176. arbitrary number of tasks and interrupt contexts) cause a
  177. deadlock.
  178. In short, this feature enables the kernel to report locking
  179. related deadlocks before they actually occur.
  180. The proof does not depend on how hard and complex a
  181. deadlock scenario would be to trigger: how many
  182. participant CPUs, tasks and irq-contexts would be needed
  183. for it to trigger. The proof also does not depend on
  184. timing: if a race and a resulting deadlock is possible
  185. theoretically (no matter how unlikely the race scenario
  186. is), it will be proven so and will immediately be
  187. reported by the kernel (once the event is observed that
  188. makes the deadlock theoretically possible).
  189. If a deadlock is impossible (i.e. the locking rules, as
  190. observed by the kernel, are mathematically correct), the
  191. kernel reports nothing.
  192. NOTE: this feature can also be enabled for rwlocks, mutexes
  193. and rwsems - in which case all dependencies between these
  194. different locking variants are observed and mapped too, and
  195. the proof of observed correctness is also maintained for an
  196. arbitrary combination of these separate locking variants.
  197. For more details, see Documentation/lockdep-design.txt.
  198. config LOCKDEP
  199. bool
  200. depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
  201. select STACKTRACE
  202. select FRAME_POINTER if !X86
  203. select KALLSYMS
  204. select KALLSYMS_ALL
  205. config DEBUG_LOCKDEP
  206. bool "Lock dependency engine debugging"
  207. depends on DEBUG_KERNEL && LOCKDEP
  208. help
  209. If you say Y here, the lock dependency engine will do
  210. additional runtime checks to debug itself, at the price
  211. of more runtime overhead.
  212. config TRACE_IRQFLAGS
  213. depends on DEBUG_KERNEL
  214. bool
  215. default y
  216. depends on TRACE_IRQFLAGS_SUPPORT
  217. depends on PROVE_LOCKING
  218. config DEBUG_SPINLOCK_SLEEP
  219. bool "Spinlock debugging: sleep-inside-spinlock checking"
  220. depends on DEBUG_KERNEL
  221. help
  222. If you say Y here, various routines which may sleep will become very
  223. noisy if they are called with a spinlock held.
  224. config DEBUG_LOCKING_API_SELFTESTS
  225. bool "Locking API boot-time self-tests"
  226. depends on DEBUG_KERNEL
  227. help
  228. Say Y here if you want the kernel to run a short self-test during
  229. bootup. The self-test checks whether common types of locking bugs
  230. are detected by debugging mechanisms or not. (if you disable
  231. lock debugging then those bugs wont be detected of course.)
  232. The following locking APIs are covered: spinlocks, rwlocks,
  233. mutexes and rwsems.
  234. config STACKTRACE
  235. bool
  236. depends on DEBUG_KERNEL
  237. depends on STACKTRACE_SUPPORT
  238. config DEBUG_KOBJECT
  239. bool "kobject debugging"
  240. depends on DEBUG_KERNEL
  241. help
  242. If you say Y here, some extra kobject debugging messages will be sent
  243. to the syslog.
  244. config DEBUG_HIGHMEM
  245. bool "Highmem debugging"
  246. depends on DEBUG_KERNEL && HIGHMEM
  247. help
  248. This options enables addition error checking for high memory systems.
  249. Disable for production systems.
  250. config DEBUG_BUGVERBOSE
  251. bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
  252. depends on BUG
  253. depends on ARM || ARM26 || AVR32 || M32R || M68K || SPARC32 || SPARC64 || X86_32 || FRV || SUPERH
  254. default !EMBEDDED
  255. help
  256. Say Y here to make BUG() panics output the file name and line number
  257. of the BUG call as well as the EIP and oops trace. This aids
  258. debugging but costs about 70-100K of memory.
  259. config DEBUG_INFO
  260. bool "Compile the kernel with debug info"
  261. depends on DEBUG_KERNEL
  262. help
  263. If you say Y here the resulting kernel image will include
  264. debugging info resulting in a larger kernel image.
  265. Say Y here only if you plan to debug the kernel.
  266. If unsure, say N.
  267. config DEBUG_FS
  268. bool "Debug Filesystem"
  269. depends on SYSFS
  270. help
  271. debugfs is a virtual file system that kernel developers use to put
  272. debugging files into. Enable this option to be able to read and
  273. write to these files.
  274. If unsure, say N.
  275. config DEBUG_VM
  276. bool "Debug VM"
  277. depends on DEBUG_KERNEL
  278. help
  279. Enable this to turn on extended checks in the virtual-memory system
  280. that may impact performance.
  281. If unsure, say N.
  282. config DEBUG_LIST
  283. bool "Debug linked list manipulation"
  284. depends on DEBUG_KERNEL
  285. help
  286. Enable this to turn on extended checks in the linked-list
  287. walking routines.
  288. If unsure, say N.
  289. config FRAME_POINTER
  290. bool "Compile the kernel with frame pointers"
  291. depends on DEBUG_KERNEL && (X86 || CRIS || M68K || M68KNOMMU || FRV || UML || S390 || AVR32 || SUPERH)
  292. default y if DEBUG_INFO && UML
  293. help
  294. If you say Y here the resulting kernel image will be slightly larger
  295. and slower, but it might give very useful debugging information on
  296. some architectures or if you use external debuggers.
  297. If you don't debug the kernel, you can say N.
  298. config UNWIND_INFO
  299. bool "Compile the kernel with frame unwind information"
  300. depends on !IA64 && !PARISC && !ARM
  301. depends on !MODULES || !(MIPS || PPC || SUPERH || V850)
  302. help
  303. If you say Y here the resulting kernel image will be slightly larger
  304. but not slower, and it will give very useful debugging information.
  305. If you don't debug the kernel, you can say N, but we may not be able
  306. to solve problems without frame unwind information or frame pointers.
  307. config STACK_UNWIND
  308. bool "Stack unwind support"
  309. depends on UNWIND_INFO
  310. depends on X86
  311. help
  312. This enables more precise stack traces, omitting all unrelated
  313. occurrences of pointers into kernel code from the dump.
  314. config FORCED_INLINING
  315. bool "Force gcc to inline functions marked 'inline'"
  316. depends on DEBUG_KERNEL
  317. default y
  318. help
  319. This option determines if the kernel forces gcc to inline the functions
  320. developers have marked 'inline'. Doing so takes away freedom from gcc to
  321. do what it thinks is best, which is desirable for the gcc 3.x series of
  322. compilers. The gcc 4.x series have a rewritten inlining algorithm and
  323. disabling this option will generate a smaller kernel there. Hopefully
  324. this algorithm is so good that allowing gcc4 to make the decision can
  325. become the default in the future, until then this option is there to
  326. test gcc for this.
  327. config HEADERS_CHECK
  328. bool "Run 'make headers_check' when building vmlinux"
  329. depends on !UML
  330. help
  331. This option will extract the user-visible kernel headers whenever
  332. building the kernel, and will run basic sanity checks on them to
  333. ensure that exported files do not attempt to include files which
  334. were not exported, etc.
  335. If you're making modifications to header files which are
  336. relevant for userspace, say 'Y', and check the headers
  337. exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
  338. your build tree), to make sure they're suitable.
  339. config RCU_TORTURE_TEST
  340. tristate "torture tests for RCU"
  341. depends on DEBUG_KERNEL
  342. default n
  343. help
  344. This option provides a kernel module that runs torture tests
  345. on the RCU infrastructure. The kernel module may be built
  346. after the fact on the running kernel to be tested, if desired.
  347. Say Y here if you want RCU torture tests to start automatically
  348. at boot time (you probably don't).
  349. Say M if you want the RCU torture tests to build as a module.
  350. Say N if you are unsure.
  351. config LKDTM
  352. tristate "Linux Kernel Dump Test Tool Module"
  353. depends on KPROBES
  354. default n
  355. help
  356. This module enables testing of the different dumping mechanisms by
  357. inducing system failures at predefined crash points.
  358. If you don't need it: say N
  359. Choose M here to compile this code as a module. The module will be
  360. called lkdtm.
  361. Documentation on how to use the module can be found in
  362. drivers/misc/lkdtm.c