| blob | dd373c8ee94399efad67ad5bc3adf57e51cf4a3d |
2 config PRINTK_TIME
3 bool "Show timing information on printks"
4 depends on PRINTK
5 help
6 Selecting this option causes timing information to be
7 included in printk output. This allows you to measure
8 the interval between kernel operations, including bootup
9 operations. This is useful for identifying long delays
10 in kernel startup. Or add printk.time=1 at boot-time.
11 See Documentation/kernel-parameters.txt
13 config DEFAULT_MESSAGE_LOGLEVEL
14 int "Default message log level (1-7)"
15 range 1 7
16 default "4"
17 help
18 Default log level for printk statements with no specified priority.
20 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
21 that are auditing their logs closely may want to set it to a lower
22 priority.
24 config ENABLE_WARN_DEPRECATED
25 bool "Enable __deprecated logic"
26 default y
27 help
28 Enable the __deprecated logic in the kernel build.
29 Disable this to suppress the "warning: 'foo' is deprecated
30 (declared at kernel/power/somefile.c:1234)" messages.
32 config ENABLE_MUST_CHECK
33 bool "Enable __must_check logic"
34 default y
35 help
36 Enable the __must_check logic in the kernel build. Disable this to
37 suppress the "warning: ignoring return value of 'foo', declared with
38 attribute warn_unused_result" messages.
40 config FRAME_WARN
41 int "Warn for stack frames larger than (needs gcc 4.4)"
42 range 0 8192
43 default 1024 if !64BIT
44 default 2048 if 64BIT
45 help
46 Tell gcc to warn at build time for stack frames larger than this.
47 Setting this too low will cause a lot of warnings.
48 Setting it to 0 disables the warning.
49 Requires gcc 4.4
51 config MAGIC_SYSRQ
52 bool "Magic SysRq key"
53 depends on !UML
54 help
55 If you say Y here, you will have some control over the system even
56 if the system crashes for example during kernel debugging (e.g., you
57 will be able to flush the buffer cache to disk, reboot the system
58 immediately or dump some status information). This is accomplished
59 by pressing various keys while holding SysRq (Alt+PrintScreen). It
60 also works on a serial console (on PC hardware at least), if you
61 send a BREAK and then within 5 seconds a command keypress. The
62 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
63 unless you really know what this hack does.
65 config STRIP_ASM_SYMS
66 bool "Strip assembler-generated symbols during link"
67 default n
68 help
69 Strip internal assembler-generated symbols during a link (symbols
70 that look like '.Lxxx') so they don't pollute the output of
71 get_wchan() and suchlike.
73 config UNUSED_SYMBOLS
74 bool "Enable unused/obsolete exported symbols"
75 default y if X86
76 help
77 Unused but exported symbols make the kernel needlessly bigger. For
78 that reason most of these unused exports will soon be removed. This
79 option is provided temporarily to provide a transition period in case
80 some external kernel module needs one of these symbols anyway. If you
81 encounter such a case in your module, consider if you are actually
82 using the right API. (rationale: since nobody in the kernel is using
83 this in a module, there is a pretty good chance it's actually the
84 wrong interface to use). If you really need the symbol, please send a
85 mail to the linux kernel mailing list mentioning the symbol and why
86 you really need it, and what the merge plan to the mainline kernel for
87 your module is.
89 config DEBUG_FS
90 bool "Debug Filesystem"
91 help
92 debugfs is a virtual file system that kernel developers use to put
93 debugging files into. Enable this option to be able to read and
94 write to these files.
96 For detailed documentation on the debugfs API, see
97 Documentation/DocBook/filesystems.
99 If unsure, say N.
101 config HEADERS_CHECK
102 bool "Run 'make headers_check' when building vmlinux"
103 depends on !UML
104 help
105 This option will extract the user-visible kernel headers whenever
106 building the kernel, and will run basic sanity checks on them to
107 ensure that exported files do not attempt to include files which
108 were not exported, etc.
110 If you're making modifications to header files which are
111 relevant for userspace, say 'Y', and check the headers
112 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
113 your build tree), to make sure they're suitable.
115 config DEBUG_SECTION_MISMATCH
116 bool "Enable full Section mismatch analysis"
117 help
118 The section mismatch analysis checks if there are illegal
119 references from one section to another section.
120 Linux will during link or during runtime drop some sections
121 and any use of code/data previously in these sections will
122 most likely result in an oops.
123 In the code functions and variables are annotated with
124 __init, __devinit etc. (see full list in include/linux/init.h)
125 which results in the code/data being placed in specific sections.
126 The section mismatch analysis is always done after a full
127 kernel build but enabling this option will in addition
128 do the following:
129 - Add the option -fno-inline-functions-called-once to gcc
130 When inlining a function annotated __init in a non-init
131 function we would lose the section information and thus
132 the analysis would not catch the illegal reference.
133 This option tells gcc to inline less but will also
134 result in a larger kernel.
135 - Run the section mismatch analysis for each module/built-in.o
136 When we run the section mismatch analysis on vmlinux.o we
137 lose valueble information about where the mismatch was
138 introduced.
139 Running the analysis for each module/built-in.o file
140 will tell where the mismatch happens much closer to the
141 source. The drawback is that we will report the same
142 mismatch at least twice.
143 - Enable verbose reporting from modpost to help solving
144 the section mismatches reported.
146 config DEBUG_KERNEL
147 bool "Kernel debugging"
148 help
149 Say Y here if you are developing drivers or trying to debug and
150 identify kernel problems.
152 config DEBUG_SHIRQ
153 bool "Debug shared IRQ handlers"
154 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
155 help
156 Enable this to generate a spurious interrupt as soon as a shared
157 interrupt handler is registered, and just before one is deregistered.
158 Drivers ought to be able to handle interrupts coming in at those
159 points; some don't and need to be caught.
161 config LOCKUP_DETECTOR
162 bool "Detect Hard and Soft Lockups"
163 depends on DEBUG_KERNEL && !S390
164 help
165 Say Y here to enable the kernel to act as a watchdog to detect
166 hard and soft lockups.
168 Softlockups are bugs that cause the kernel to loop in kernel
169 mode for more than 60 seconds, without giving other tasks a
170 chance to run. The current stack trace is displayed upon
171 detection and the system will stay locked up.
173 Hardlockups are bugs that cause the CPU to loop in kernel mode
174 for more than 60 seconds, without letting other interrupts have a
175 chance to run. The current stack trace is displayed upon detection
176 and the system will stay locked up.
178 The overhead should be minimal. A periodic hrtimer runs to
179 generate interrupts and kick the watchdog task every 10-12 seconds.
180 An NMI is generated every 60 seconds or so to check for hardlockups.
182 config HARDLOCKUP_DETECTOR
183 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
184 !ARCH_HAS_NMI_WATCHDOG
186 config BOOTPARAM_HARDLOCKUP_PANIC
187 bool "Panic (Reboot) On Hard Lockups"
188 depends on LOCKUP_DETECTOR
189 help
190 Say Y here to enable the kernel to panic on "hard lockups",
191 which are bugs that cause the kernel to loop in kernel
192 mode with interrupts disabled for more than 60 seconds.
194 Say N if unsure.
196 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
197 int
198 depends on LOCKUP_DETECTOR
199 range 0 1
200 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
201 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
203 config BOOTPARAM_SOFTLOCKUP_PANIC
204 bool "Panic (Reboot) On Soft Lockups"
205 depends on LOCKUP_DETECTOR
206 help
207 Say Y here to enable the kernel to panic on "soft lockups",
208 which are bugs that cause the kernel to loop in kernel
209 mode for more than 60 seconds, without giving other tasks a
210 chance to run.
212 The panic can be used in combination with panic_timeout,
213 to cause the system to reboot automatically after a
214 lockup has been detected. This feature is useful for
215 high-availability systems that have uptime guarantees and
216 where a lockup must be resolved ASAP.
218 Say N if unsure.
220 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
221 int
222 depends on LOCKUP_DETECTOR
223 range 0 1
224 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
225 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
227 config DETECT_HUNG_TASK
228 bool "Detect Hung Tasks"
229 depends on DEBUG_KERNEL
230 default DETECT_SOFTLOCKUP
231 help
232 Say Y here to enable the kernel to detect "hung tasks",
233 which are bugs that cause the task to be stuck in
234 uninterruptible "D" state indefinitiley.
236 When a hung task is detected, the kernel will print the
237 current stack trace (which you should report), but the
238 task will stay in uninterruptible state. If lockdep is
239 enabled then all held locks will also be reported. This
240 feature has negligible overhead.
242 config DEFAULT_HUNG_TASK_TIMEOUT
243 int "Default timeout for hung task detection (in seconds)"
244 depends on DETECT_HUNG_TASK
245 default 120
246 help
247 This option controls the default timeout (in seconds) used
248 to determine when a task has become non-responsive and should
249 be considered hung.
251 It can be adjusted at runtime via the kernel.hung_task_timeout
252 sysctl or by writing a value to /proc/sys/kernel/hung_task_timeout.
254 A timeout of 0 disables the check. The default is two minutes.
255 Keeping the default should be fine in most cases.
257 config BOOTPARAM_HUNG_TASK_PANIC
258 bool "Panic (Reboot) On Hung Tasks"
259 depends on DETECT_HUNG_TASK
260 help
261 Say Y here to enable the kernel to panic on "hung tasks",
262 which are bugs that cause the kernel to leave a task stuck
263 in uninterruptible "D" state.
265 The panic can be used in combination with panic_timeout,
266 to cause the system to reboot automatically after a
267 hung task has been detected. This feature is useful for
268 high-availability systems that have uptime guarantees and
269 where a hung tasks must be resolved ASAP.
271 Say N if unsure.
273 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
274 int
275 depends on DETECT_HUNG_TASK
276 range 0 1
277 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
278 default 1 if BOOTPARAM_HUNG_TASK_PANIC
280 config SCHED_DEBUG
281 bool "Collect scheduler debugging info"
282 depends on DEBUG_KERNEL && PROC_FS
283 default y
284 help
285 If you say Y here, the /proc/sched_debug file will be provided
286 that can help debug the scheduler. The runtime overhead of this
287 option is minimal.
289 config SCHEDSTATS
290 bool "Collect scheduler statistics"
291 depends on DEBUG_KERNEL && PROC_FS
292 help
293 If you say Y here, additional code will be inserted into the
294 scheduler and related routines to collect statistics about
295 scheduler behavior and provide them in /proc/schedstat. These
296 stats may be useful for both tuning and debugging the scheduler
297 If you aren't debugging the scheduler or trying to tune a specific
298 application, you can say N to avoid the very slight overhead
299 this adds.
301 config TIMER_STATS
302 bool "Collect kernel timers statistics"
303 depends on DEBUG_KERNEL && PROC_FS
304 help
305 If you say Y here, additional code will be inserted into the
306 timer routines to collect statistics about kernel timers being
307 reprogrammed. The statistics can be read from /proc/timer_stats.
308 The statistics collection is started by writing 1 to /proc/timer_stats,
309 writing 0 stops it. This feature is useful to collect information
310 about timer usage patterns in kernel and userspace. This feature
311 is lightweight if enabled in the kernel config but not activated
312 (it defaults to deactivated on bootup and will only be activated
313 if some application like powertop activates it explicitly).
315 config DEBUG_OBJECTS
316 bool "Debug object operations"
317 depends on DEBUG_KERNEL
318 help
319 If you say Y here, additional code will be inserted into the
320 kernel to track the life time of various objects and validate
321 the operations on those objects.
323 config DEBUG_OBJECTS_SELFTEST
324 bool "Debug objects selftest"
325 depends on DEBUG_OBJECTS
326 help
327 This enables the selftest of the object debug code.
329 config DEBUG_OBJECTS_FREE
330 bool "Debug objects in freed memory"
331 depends on DEBUG_OBJECTS
332 help
333 This enables checks whether a k/v free operation frees an area
334 which contains an object which has not been deactivated
335 properly. This can make kmalloc/kfree-intensive workloads
336 much slower.
338 config DEBUG_OBJECTS_TIMERS
339 bool "Debug timer objects"
340 depends on DEBUG_OBJECTS
341 help
342 If you say Y here, additional code will be inserted into the
343 timer routines to track the life time of timer objects and
344 validate the timer operations.
346 config DEBUG_OBJECTS_WORK
347 bool "Debug work objects"
348 depends on DEBUG_OBJECTS
349 help
350 If you say Y here, additional code will be inserted into the
351 work queue routines to track the life time of work objects and
352 validate the work operations.
354 config DEBUG_OBJECTS_RCU_HEAD
355 bool "Debug RCU callbacks objects"
356 depends on DEBUG_OBJECTS
357 help
358 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
360 config DEBUG_OBJECTS_PERCPU_COUNTER
361 bool "Debug percpu counter objects"
362 depends on DEBUG_OBJECTS
363 help
364 If you say Y here, additional code will be inserted into the
365 percpu counter routines to track the life time of percpu counter
366 objects and validate the percpu counter operations.
368 config DEBUG_OBJECTS_ENABLE_DEFAULT
369 int "debug_objects bootup default value (0-1)"
370 range 0 1
371 default "1"
372 depends on DEBUG_OBJECTS
373 help
374 Debug objects boot parameter default value
376 config DEBUG_SLAB
377 bool "Debug slab memory allocations"
378 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
379 help
380 Say Y here to have the kernel do limited verification on memory
381 allocation as well as poisoning memory on free to catch use of freed
382 memory. This can make kmalloc/kfree-intensive workloads much slower.
384 config DEBUG_SLAB_LEAK
385 bool "Memory leak debugging"
386 depends on DEBUG_SLAB
388 config SLUB_DEBUG_ON
389 bool "SLUB debugging on by default"
390 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
391 default n
392 help
393 Boot with debugging on by default. SLUB boots by default with
394 the runtime debug capabilities switched off. Enabling this is
395 equivalent to specifying the "slub_debug" parameter on boot.
396 There is no support for more fine grained debug control like
397 possible with slub_debug=xxx. SLUB debugging may be switched
398 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
399 "slub_debug=-".
401 config SLUB_STATS
402 default n
403 bool "Enable SLUB performance statistics"
404 depends on SLUB && SYSFS
405 help
406 SLUB statistics are useful to debug SLUBs allocation behavior in
407 order find ways to optimize the allocator. This should never be
408 enabled for production use since keeping statistics slows down
409 the allocator by a few percentage points. The slabinfo command
410 supports the determination of the most active slabs to figure
411 out which slabs are relevant to a particular load.
412 Try running: slabinfo -DA
414 config DEBUG_KMEMLEAK
415 bool "Kernel memory leak detector"
416 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
417 (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
419 select DEBUG_FS
420 select STACKTRACE if STACKTRACE_SUPPORT
421 select KALLSYMS
422 select CRC32
423 help
424 Say Y here if you want to enable the memory leak
425 detector. The memory allocation/freeing is traced in a way
426 similar to the Boehm's conservative garbage collector, the
427 difference being that the orphan objects are not freed but
428 only shown in /sys/kernel/debug/kmemleak. Enabling this
429 feature will introduce an overhead to memory
430 allocations. See Documentation/kmemleak.txt for more
431 details.
433 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
434 of finding leaks due to the slab objects poisoning.
436 In order to access the kmemleak file, debugfs needs to be
437 mounted (usually at /sys/kernel/debug).
439 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
440 int "Maximum kmemleak early log entries"
441 depends on DEBUG_KMEMLEAK
442 range 200 40000
443 default 400
444 help
445 Kmemleak must track all the memory allocations to avoid
446 reporting false positives. Since memory may be allocated or
447 freed before kmemleak is initialised, an early log buffer is
448 used to store these actions. If kmemleak reports "early log
449 buffer exceeded", please increase this value.
451 config DEBUG_KMEMLEAK_TEST
452 tristate "Simple test for the kernel memory leak detector"
453 depends on DEBUG_KMEMLEAK && m
454 help
455 This option enables a module that explicitly leaks memory.
457 If unsure, say N.
459 config DEBUG_KMEMLEAK_DEFAULT_OFF
460 bool "Default kmemleak to off"
461 depends on DEBUG_KMEMLEAK
462 help
463 Say Y here to disable kmemleak by default. It can then be enabled
464 on the command line via kmemleak=on.
466 config DEBUG_PREEMPT
467 bool "Debug preemptible kernel"
468 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
469 default y
470 help
471 If you say Y here then the kernel will use a debug variant of the
472 commonly used smp_processor_id() function and will print warnings
473 if kernel code uses it in a preemption-unsafe way. Also, the kernel
474 will detect preemption count underflows.
476 config DEBUG_RT_MUTEXES
477 bool "RT Mutex debugging, deadlock detection"
478 depends on DEBUG_KERNEL && RT_MUTEXES
479 help
480 This allows rt mutex semantics violations and rt mutex related
481 deadlocks (lockups) to be detected and reported automatically.
483 config DEBUG_PI_LIST
484 bool
485 default y
486 depends on DEBUG_RT_MUTEXES
488 config RT_MUTEX_TESTER
489 bool "Built-in scriptable tester for rt-mutexes"
490 depends on DEBUG_KERNEL && RT_MUTEXES
491 help
492 This option enables a rt-mutex tester.
494 config DEBUG_SPINLOCK
495 bool "Spinlock and rw-lock debugging: basic checks"
496 depends on DEBUG_KERNEL
497 help
498 Say Y here and build SMP to catch missing spinlock initialization
499 and certain other kinds of spinlock errors commonly made. This is
500 best used in conjunction with the NMI watchdog so that spinlock
501 deadlocks are also debuggable.
503 config DEBUG_MUTEXES
504 bool "Mutex debugging: basic checks"
505 depends on DEBUG_KERNEL
506 help
507 This feature allows mutex semantics violations to be detected and
508 reported.
510 config DEBUG_LOCK_ALLOC
511 bool "Lock debugging: detect incorrect freeing of live locks"
512 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
513 select DEBUG_SPINLOCK
514 select DEBUG_MUTEXES
515 select LOCKDEP
516 help
517 This feature will check whether any held lock (spinlock, rwlock,
518 mutex or rwsem) is incorrectly freed by the kernel, via any of the
519 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
520 vfree(), etc.), whether a live lock is incorrectly reinitialized via
521 spin_lock_init()/mutex_init()/etc., or whether there is any lock
522 held during task exit.
524 config PROVE_LOCKING
525 bool "Lock debugging: prove locking correctness"
526 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
527 select LOCKDEP
528 select DEBUG_SPINLOCK
529 select DEBUG_MUTEXES
530 select DEBUG_LOCK_ALLOC
531 select TRACE_IRQFLAGS
532 default n
533 help
534 This feature enables the kernel to prove that all locking
535 that occurs in the kernel runtime is mathematically
536 correct: that under no circumstance could an arbitrary (and
537 not yet triggered) combination of observed locking
538 sequences (on an arbitrary number of CPUs, running an
539 arbitrary number of tasks and interrupt contexts) cause a
540 deadlock.
542 In short, this feature enables the kernel to report locking
543 related deadlocks before they actually occur.
545 The proof does not depend on how hard and complex a
546 deadlock scenario would be to trigger: how many
547 participant CPUs, tasks and irq-contexts would be needed
548 for it to trigger. The proof also does not depend on
549 timing: if a race and a resulting deadlock is possible
550 theoretically (no matter how unlikely the race scenario
551 is), it will be proven so and will immediately be
552 reported by the kernel (once the event is observed that
553 makes the deadlock theoretically possible).
555 If a deadlock is impossible (i.e. the locking rules, as
556 observed by the kernel, are mathematically correct), the
557 kernel reports nothing.
559 NOTE: this feature can also be enabled for rwlocks, mutexes
560 and rwsems - in which case all dependencies between these
561 different locking variants are observed and mapped too, and
562 the proof of observed correctness is also maintained for an
563 arbitrary combination of these separate locking variants.
565 For more details, see Documentation/lockdep-design.txt.
567 config PROVE_RCU
568 bool "RCU debugging: prove RCU correctness"
569 depends on PROVE_LOCKING
570 default n
571 help
572 This feature enables lockdep extensions that check for correct
573 use of RCU APIs. This is currently under development. Say Y
574 if you want to debug RCU usage or help work on the PROVE_RCU
575 feature.
577 Say N if you are unsure.
579 config PROVE_RCU_REPEATEDLY
580 bool "RCU debugging: don't disable PROVE_RCU on first splat"
581 depends on PROVE_RCU
582 default n
583 help
584 By itself, PROVE_RCU will disable checking upon issuing the
585 first warning (or "splat"). This feature prevents such
586 disabling, allowing multiple RCU-lockdep warnings to be printed
587 on a single reboot.
589 Say Y to allow multiple RCU-lockdep warnings per boot.
591 Say N if you are unsure.
593 config SPARSE_RCU_POINTER
594 bool "RCU debugging: sparse-based checks for pointer usage"
595 default n
596 help
597 This feature enables the __rcu sparse annotation for
598 RCU-protected pointers. This annotation will cause sparse
599 to flag any non-RCU used of annotated pointers. This can be
600 helpful when debugging RCU usage. Please note that this feature
601 is not intended to enforce code cleanliness; it is instead merely
602 a debugging aid.
604 Say Y to make sparse flag questionable use of RCU-protected pointers
606 Say N if you are unsure.
608 config LOCKDEP
609 bool
610 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
611 select STACKTRACE
612 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
613 select KALLSYMS
614 select KALLSYMS_ALL
616 config LOCK_STAT
617 bool "Lock usage statistics"
618 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
619 select LOCKDEP
620 select DEBUG_SPINLOCK
621 select DEBUG_MUTEXES
622 select DEBUG_LOCK_ALLOC
623 default n
624 help
625 This feature enables tracking lock contention points
627 For more details, see Documentation/lockstat.txt
629 This also enables lock events required by "perf lock",
630 subcommand of perf.
631 If you want to use "perf lock", you also need to turn on
632 CONFIG_EVENT_TRACING.
634 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
635 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
637 config DEBUG_LOCKDEP
638 bool "Lock dependency engine debugging"
639 depends on DEBUG_KERNEL && LOCKDEP
640 help
641 If you say Y here, the lock dependency engine will do
642 additional runtime checks to debug itself, at the price
643 of more runtime overhead.
645 config TRACE_IRQFLAGS
646 bool
647 help
648 Enables hooks to interrupt enabling and disabling for
649 either tracing or lock debugging.
651 config DEBUG_SPINLOCK_SLEEP
652 bool "Spinlock debugging: sleep-inside-spinlock checking"
653 depends on DEBUG_KERNEL
654 help
655 If you say Y here, various routines which may sleep will become very
656 noisy if they are called with a spinlock held.
658 config DEBUG_LOCKING_API_SELFTESTS
659 bool "Locking API boot-time self-tests"
660 depends on DEBUG_KERNEL
661 help
662 Say Y here if you want the kernel to run a short self-test during
663 bootup. The self-test checks whether common types of locking bugs
664 are detected by debugging mechanisms or not. (if you disable
665 lock debugging then those bugs wont be detected of course.)
666 The following locking APIs are covered: spinlocks, rwlocks,
667 mutexes and rwsems.
669 config STACKTRACE
670 bool
671 depends on STACKTRACE_SUPPORT
673 config DEBUG_STACK_USAGE
674 bool "Stack utilization instrumentation"
675 depends on DEBUG_KERNEL
676 help
677 Enables the display of the minimum amount of free stack which each
678 task has ever had available in the sysrq-T and sysrq-P debug output.
680 This option will slow down process creation somewhat.
682 config DEBUG_KOBJECT
683 bool "kobject debugging"
684 depends on DEBUG_KERNEL
685 help
686 If you say Y here, some extra kobject debugging messages will be sent
687 to the syslog.
689 config DEBUG_HIGHMEM
690 bool "Highmem debugging"
691 depends on DEBUG_KERNEL && HIGHMEM
692 help
693 This options enables addition error checking for high memory systems.
694 Disable for production systems.
696 config DEBUG_BUGVERBOSE
697 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
698 depends on BUG
699 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
700 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || TILE
701 default y
702 help
703 Say Y here to make BUG() panics output the file name and line number
704 of the BUG call as well as the EIP and oops trace. This aids
705 debugging but costs about 70-100K of memory.
707 config DEBUG_INFO
708 bool "Compile the kernel with debug info"
709 depends on DEBUG_KERNEL
710 help
711 If you say Y here the resulting kernel image will include
712 debugging info resulting in a larger kernel image.
713 This adds debug symbols to the kernel and modules (gcc -g), and
714 is needed if you intend to use kernel crashdump or binary object
715 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
716 Say Y here only if you plan to debug the kernel.
718 If unsure, say N.
720 config DEBUG_INFO_REDUCED
721 bool "Reduce debugging information"
722 depends on DEBUG_INFO
723 help
724 If you say Y here gcc is instructed to generate less debugging
725 information for structure types. This means that tools that
726 need full debugging information (like kgdb or systemtap) won't
727 be happy. But if you merely need debugging information to
728 resolve line numbers there is no loss. Advantage is that
729 build directory object sizes shrink dramatically over a full
730 DEBUG_INFO build and compile times are reduced too.
731 Only works with newer gcc versions.
733 config DEBUG_VM
734 bool "Debug VM"
735 depends on DEBUG_KERNEL
736 help
737 Enable this to turn on extended checks in the virtual-memory system
738 that may impact performance.
740 If unsure, say N.
742 config DEBUG_VIRTUAL
743 bool "Debug VM translations"
744 depends on DEBUG_KERNEL && X86
745 help
746 Enable some costly sanity checks in virtual to page code. This can
747 catch mistakes with virt_to_page() and friends.
749 If unsure, say N.
751 config DEBUG_NOMMU_REGIONS
752 bool "Debug the global anon/private NOMMU mapping region tree"
753 depends on DEBUG_KERNEL && !MMU
754 help
755 This option causes the global tree of anonymous and private mapping
756 regions to be regularly checked for invalid topology.
758 config DEBUG_WRITECOUNT
759 bool "Debug filesystem writers count"
760 depends on DEBUG_KERNEL
761 help
762 Enable this to catch wrong use of the writers count in struct
763 vfsmount. This will increase the size of each file struct by
764 32 bits.
766 If unsure, say N.
768 config DEBUG_MEMORY_INIT
769 bool "Debug memory initialisation" if EXPERT
770 default !EXPERT
771 help
772 Enable this for additional checks during memory initialisation.
773 The sanity checks verify aspects of the VM such as the memory model
774 and other information provided by the architecture. Verbose
775 information will be printed at KERN_DEBUG loglevel depending
776 on the mminit_loglevel= command-line option.
778 If unsure, say Y
780 config DEBUG_LIST
781 bool "Debug linked list manipulation"
782 depends on DEBUG_KERNEL
783 help
784 Enable this to turn on extended checks in the linked-list
785 walking routines.
787 If unsure, say N.
789 config TEST_LIST_SORT
790 bool "Linked list sorting test"
791 depends on DEBUG_KERNEL
792 help
793 Enable this to turn on 'list_sort()' function test. This test is
794 executed only once during system boot, so affects only boot time.
796 If unsure, say N.
798 config DEBUG_SG
799 bool "Debug SG table operations"
800 depends on DEBUG_KERNEL
801 help
802 Enable this to turn on checks on scatter-gather tables. This can
803 help find problems with drivers that do not properly initialize
804 their sg tables.
806 If unsure, say N.
808 config DEBUG_NOTIFIERS
809 bool "Debug notifier call chains"
810 depends on DEBUG_KERNEL
811 help
812 Enable this to turn on sanity checking for notifier call chains.
813 This is most useful for kernel developers to make sure that
814 modules properly unregister themselves from notifier chains.
815 This is a relatively cheap check but if you care about maximum
816 performance, say N.
818 config DEBUG_CREDENTIALS
819 bool "Debug credential management"
820 depends on DEBUG_KERNEL
821 help
822 Enable this to turn on some debug checking for credential
823 management. The additional code keeps track of the number of
824 pointers from task_structs to any given cred struct, and checks to
825 see that this number never exceeds the usage count of the cred
826 struct.
828 Furthermore, if SELinux is enabled, this also checks that the
829 security pointer in the cred struct is never seen to be invalid.
831 If unsure, say N.
833 #
834 # Select this config option from the architecture Kconfig, if it
835 # it is preferred to always offer frame pointers as a config
836 # option on the architecture (regardless of KERNEL_DEBUG):
837 #
838 config ARCH_WANT_FRAME_POINTERS
839 bool
840 help
842 config FRAME_POINTER
843 bool "Compile the kernel with frame pointers"
844 depends on DEBUG_KERNEL && \
845 (CRIS || M68K || FRV || UML || \
846 AVR32 || SUPERH || BLACKFIN || MN10300) || \
847 ARCH_WANT_FRAME_POINTERS
848 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
849 help
850 If you say Y here the resulting kernel image will be slightly
851 larger and slower, but it gives very useful debugging information
852 in case of kernel bugs. (precise oopses/stacktraces/warnings)
854 config BOOT_PRINTK_DELAY
855 bool "Delay each boot printk message by N milliseconds"
856 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
857 help
858 This build option allows you to read kernel boot messages
859 by inserting a short delay after each one. The delay is
860 specified in milliseconds on the kernel command line,
861 using "boot_delay=N".
863 It is likely that you would also need to use "lpj=M" to preset
864 the "loops per jiffie" value.
865 See a previous boot log for the "lpj" value to use for your
866 system, and then set "lpj=M" before setting "boot_delay=N".
867 NOTE: Using this option may adversely affect SMP systems.
868 I.e., processors other than the first one may not boot up.
869 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
870 what it believes to be lockup conditions.
872 config RCU_TORTURE_TEST
873 tristate "torture tests for RCU"
874 depends on DEBUG_KERNEL
875 default n
876 help
877 This option provides a kernel module that runs torture tests
878 on the RCU infrastructure. The kernel module may be built
879 after the fact on the running kernel to be tested, if desired.
881 Say Y here if you want RCU torture tests to be built into
882 the kernel.
883 Say M if you want the RCU torture tests to build as a module.
884 Say N if you are unsure.
886 config RCU_TORTURE_TEST_RUNNABLE
887 bool "torture tests for RCU runnable by default"
888 depends on RCU_TORTURE_TEST = y
889 default n
890 help
891 This option provides a way to build the RCU torture tests
892 directly into the kernel without them starting up at boot
893 time. You can use /proc/sys/kernel/rcutorture_runnable
894 to manually override this setting. This /proc file is
895 available only when the RCU torture tests have been built
896 into the kernel.
898 Say Y here if you want the RCU torture tests to start during
899 boot (you probably don't).
900 Say N here if you want the RCU torture tests to start only
901 after being manually enabled via /proc.
903 config RCU_CPU_STALL_TIMEOUT
904 int "RCU CPU stall timeout in seconds"
905 depends on TREE_RCU || TREE_PREEMPT_RCU
906 range 3 300
907 default 60
908 help
909 If a given RCU grace period extends more than the specified
910 number of seconds, a CPU stall warning is printed. If the
911 RCU grace period persists, additional CPU stall warnings are
912 printed at more widely spaced intervals.
914 config RCU_CPU_STALL_VERBOSE
915 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
916 depends on TREE_PREEMPT_RCU
917 default y
918 help
919 This option causes RCU to printk detailed per-task information
920 for any tasks that are stalling the current RCU grace period.
922 Say N if you are unsure.
924 Say Y if you want to enable such checks.
926 config KPROBES_SANITY_TEST
927 bool "Kprobes sanity tests"
928 depends on DEBUG_KERNEL
929 depends on KPROBES
930 default n
931 help
932 This option provides for testing basic kprobes functionality on
933 boot. A sample kprobe, jprobe and kretprobe are inserted and
934 verified for functionality.
936 Say N if you are unsure.
938 config BACKTRACE_SELF_TEST
939 tristate "Self test for the backtrace code"
940 depends on DEBUG_KERNEL
941 default n
942 help
943 This option provides a kernel module that can be used to test
944 the kernel stack backtrace code. This option is not useful
945 for distributions or general kernels, but only for kernel
946 developers working on architecture code.
948 Note that if you want to also test saved backtraces, you will
949 have to enable STACKTRACE as well.
951 Say N if you are unsure.
953 config DEBUG_BLOCK_EXT_DEVT
954 bool "Force extended block device numbers and spread them"
955 depends on DEBUG_KERNEL
956 depends on BLOCK
957 default n
958 help
959 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
960 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
961 YOU ARE DOING. Distros, please enable this and fix whatever
962 is broken.
964 Conventionally, block device numbers are allocated from
965 predetermined contiguous area. However, extended block area
966 may introduce non-contiguous block device numbers. This
967 option forces most block device numbers to be allocated from
968 the extended space and spreads them to discover kernel or
969 userland code paths which assume predetermined contiguous
970 device number allocation.
972 Note that turning on this debug option shuffles all the
973 device numbers for all IDE and SCSI devices including libata
974 ones, so root partition specified using device number
975 directly (via rdev or root=MAJ:MIN) won't work anymore.
976 Textual device names (root=/dev/sdXn) will continue to work.
978 Say N if you are unsure.
980 config DEBUG_FORCE_WEAK_PER_CPU
981 bool "Force weak per-cpu definitions"
982 depends on DEBUG_KERNEL
983 help
984 s390 and alpha require percpu variables in modules to be
985 defined weak to work around addressing range issue which
986 puts the following two restrictions on percpu variable
987 definitions.
989 1. percpu symbols must be unique whether static or not
990 2. percpu variables can't be defined inside a function
992 To ensure that generic code follows the above rules, this
993 option forces all percpu variables to be defined as weak.
995 config DEBUG_PER_CPU_MAPS
996 bool "Debug access to per_cpu maps"
997 depends on DEBUG_KERNEL
998 depends on SMP
999 help
1000 Say Y to verify that the per_cpu map being accessed has
1001 been set up. This adds a fair amount of code to kernel memory
1002 and decreases performance.
1004 Say N if unsure.
1006 config LKDTM
1007 tristate "Linux Kernel Dump Test Tool Module"
1008 depends on DEBUG_FS
1009 depends on BLOCK
1010 default n
1011 help
1012 This module enables testing of the different dumping mechanisms by
1013 inducing system failures at predefined crash points.
1014 If you don't need it: say N
1015 Choose M here to compile this code as a module. The module will be
1016 called lkdtm.
1018 Documentation on how to use the module can be found in
1019 Documentation/fault-injection/provoke-crashes.txt
1021 config CPU_NOTIFIER_ERROR_INJECT
1022 tristate "CPU notifier error injection module"
1023 depends on HOTPLUG_CPU && DEBUG_KERNEL
1024 help
1025 This option provides a kernel module that can be used to test
1026 the error handling of the cpu notifiers
1028 To compile this code as a module, choose M here: the module will
1029 be called cpu-notifier-error-inject.
1031 If unsure, say N.
1033 config FAULT_INJECTION
1034 bool "Fault-injection framework"
1035 depends on DEBUG_KERNEL
1036 help
1037 Provide fault-injection framework.
1038 For more details, see Documentation/fault-injection/.
1040 config FAILSLAB
1041 bool "Fault-injection capability for kmalloc"
1042 depends on FAULT_INJECTION
1043 depends on SLAB || SLUB
1044 help
1045 Provide fault-injection capability for kmalloc.
1047 config FAIL_PAGE_ALLOC
1048 bool "Fault-injection capabilitiy for alloc_pages()"
1049 depends on FAULT_INJECTION
1050 help
1051 Provide fault-injection capability for alloc_pages().
1053 config FAIL_MAKE_REQUEST
1054 bool "Fault-injection capability for disk IO"
1055 depends on FAULT_INJECTION && BLOCK
1056 help
1057 Provide fault-injection capability for disk IO.
1059 config FAIL_IO_TIMEOUT
1060 bool "Fault-injection capability for faking disk interrupts"
1061 depends on FAULT_INJECTION && BLOCK
1062 help
1063 Provide fault-injection capability on end IO handling. This
1064 will make the block layer "forget" an interrupt as configured,
1065 thus exercising the error handling.
1067 Only works with drivers that use the generic timeout handling,
1068 for others it wont do anything.
1070 config FAULT_INJECTION_DEBUG_FS
1071 bool "Debugfs entries for fault-injection capabilities"
1072 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1073 help
1074 Enable configuration of fault-injection capabilities via debugfs.
1076 config FAULT_INJECTION_STACKTRACE_FILTER
1077 bool "stacktrace filter for fault-injection capabilities"
1078 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1079 depends on !X86_64
1080 select STACKTRACE
1081 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
1082 help
1083 Provide stacktrace filter for fault-injection capabilities
1085 config LATENCYTOP
1086 bool "Latency measuring infrastructure"
1087 depends on HAVE_LATENCYTOP_SUPPORT
1088 depends on DEBUG_KERNEL
1089 depends on STACKTRACE_SUPPORT
1090 depends on PROC_FS
1091 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
1092 select KALLSYMS
1093 select KALLSYMS_ALL
1094 select STACKTRACE
1095 select SCHEDSTATS
1096 select SCHED_DEBUG
1097 help
1098 Enable this option if you want to use the LatencyTOP tool
1099 to find out which userspace is blocking on what kernel operations.
1101 config SYSCTL_SYSCALL_CHECK
1102 bool "Sysctl checks"
1103 depends on SYSCTL
1104 ---help---
1105 sys_sysctl uses binary paths that have been found challenging
1106 to properly maintain and use. This enables checks that help
1107 you to keep things correct.
1109 source mm/Kconfig.debug
1110 source kernel/trace/Kconfig
1112 config PROVIDE_OHCI1394_DMA_INIT
1113 bool "Remote debugging over FireWire early on boot"
1114 depends on PCI && X86
1115 help
1116 If you want to debug problems which hang or crash the kernel early
1117 on boot and the crashing machine has a FireWire port, you can use
1118 this feature to remotely access the memory of the crashed machine
1119 over FireWire. This employs remote DMA as part of the OHCI1394
1120 specification which is now the standard for FireWire controllers.
1122 With remote DMA, you can monitor the printk buffer remotely using
1123 firescope and access all memory below 4GB using fireproxy from gdb.
1124 Even controlling a kernel debugger is possible using remote DMA.
1126 Usage:
1128 If ohci1394_dma=early is used as boot parameter, it will initialize
1129 all OHCI1394 controllers which are found in the PCI config space.
1131 As all changes to the FireWire bus such as enabling and disabling
1132 devices cause a bus reset and thereby disable remote DMA for all
1133 devices, be sure to have the cable plugged and FireWire enabled on
1134 the debugging host before booting the debug target for debugging.
1136 This code (~1k) is freed after boot. By then, the firewire stack
1137 in charge of the OHCI-1394 controllers should be used instead.
1139 See Documentation/debugging-via-ohci1394.txt for more information.
1141 config FIREWIRE_OHCI_REMOTE_DMA
1142 bool "Remote debugging over FireWire with firewire-ohci"
1143 depends on FIREWIRE_OHCI
1144 help
1145 This option lets you use the FireWire bus for remote debugging
1146 with help of the firewire-ohci driver. It enables unfiltered
1147 remote DMA in firewire-ohci.
1148 See Documentation/debugging-via-ohci1394.txt for more information.
1150 If unsure, say N.
1152 config BUILD_DOCSRC
1153 bool "Build targets in Documentation/ tree"
1154 depends on HEADERS_CHECK
1155 help
1156 This option attempts to build objects from the source files in the
1157 kernel Documentation/ tree.
1159 Say N if you are unsure.
1161 config DYNAMIC_DEBUG
1162 bool "Enable dynamic printk() support"
1163 default n
1164 depends on PRINTK
1165 depends on DEBUG_FS
1166 help
1168 Compiles debug level messages into the kernel, which would not
1169 otherwise be available at runtime. These messages can then be
1170 enabled/disabled based on various levels of scope - per source file,
1171 function, module, format string, and line number. This mechanism
1172 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1173 this compile option is a larger kernel text size of about 2%.
1175 Usage:
1177 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1178 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1179 filesystem must first be mounted before making use of this feature.
1180 We refer the control file as: <debugfs>/dynamic_debug/control. This
1181 file contains a list of the debug statements that can be enabled. The
1182 format for each line of the file is:
1184 filename:lineno [module]function flags format
1186 filename : source file of the debug statement
1187 lineno : line number of the debug statement
1188 module : module that contains the debug statement
1189 function : function that contains the debug statement
1190 flags : 'p' means the line is turned 'on' for printing
1191 format : the format used for the debug statement
1193 From a live system:
1195 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1196 # filename:lineno [module]function flags format
1197 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1198 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1199 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1201 Example usage:
1203 // enable the message at line 1603 of file svcsock.c
1204 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1205 <debugfs>/dynamic_debug/control
1207 // enable all the messages in file svcsock.c
1208 nullarbor:~ # echo -n 'file svcsock.c +p' >
1209 <debugfs>/dynamic_debug/control
1211 // enable all the messages in the NFS server module
1212 nullarbor:~ # echo -n 'module nfsd +p' >
1213 <debugfs>/dynamic_debug/control
1215 // enable all 12 messages in the function svc_process()
1216 nullarbor:~ # echo -n 'func svc_process +p' >
1217 <debugfs>/dynamic_debug/control
1219 // disable all 12 messages in the function svc_process()
1220 nullarbor:~ # echo -n 'func svc_process -p' >
1221 <debugfs>/dynamic_debug/control
1223 See Documentation/dynamic-debug-howto.txt for additional information.
1225 config DMA_API_DEBUG
1226 bool "Enable debugging of DMA-API usage"
1227 depends on HAVE_DMA_API_DEBUG
1228 help
1229 Enable this option to debug the use of the DMA API by device drivers.
1230 With this option you will be able to detect common bugs in device
1231 drivers like double-freeing of DMA mappings or freeing mappings that
1232 were never allocated.
1233 This option causes a performance degredation. Use only if you want
1234 to debug device drivers. If unsure, say N.
1236 config ATOMIC64_SELFTEST
1237 bool "Perform an atomic64_t self-test at boot"
1238 help
1239 Enable this option to test the atomic64_t functions at boot.
1241 If unsure, say N.
1243 config ASYNC_RAID6_TEST
1244 tristate "Self test for hardware accelerated raid6 recovery"
1245 depends on ASYNC_RAID6_RECOV
1246 select ASYNC_MEMCPY
1247 ---help---
1248 This is a one-shot self test that permutes through the
1249 recovery of all the possible two disk failure scenarios for a
1250 N-disk array. Recovery is performed with the asynchronous
1251 raid6 recovery routines, and will optionally use an offload
1252 engine if one is available.
1254 If unsure, say N.
1256 source "samples/Kconfig"
1258 source "lib/Kconfig.kgdb"
1260 source "lib/Kconfig.kmemcheck"
1262 config TEST_KSTRTOX
1263 tristate "Test kstrto*() family of functions at runtime"