| blob | 4d6100d83e599a0d7dcab4186875a413f977245c |
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 LOCKUP_DETECTOR
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_ATOMIC_SLEEP
652 bool "Sleep inside atomic section checking"
653 select PREEMPT_COUNT
654 depends on DEBUG_KERNEL
655 help
656 If you say Y here, various routines which may sleep will become very
657 noisy if they are called inside atomic sections: when a spinlock is
658 held, inside an rcu read side critical section, inside preempt disabled
659 sections, inside an interrupt, etc...
661 config DEBUG_LOCKING_API_SELFTESTS
662 bool "Locking API boot-time self-tests"
663 depends on DEBUG_KERNEL
664 help
665 Say Y here if you want the kernel to run a short self-test during
666 bootup. The self-test checks whether common types of locking bugs
667 are detected by debugging mechanisms or not. (if you disable
668 lock debugging then those bugs wont be detected of course.)
669 The following locking APIs are covered: spinlocks, rwlocks,
670 mutexes and rwsems.
672 config STACKTRACE
673 bool
674 depends on STACKTRACE_SUPPORT
676 config DEBUG_STACK_USAGE
677 bool "Stack utilization instrumentation"
678 depends on DEBUG_KERNEL
679 help
680 Enables the display of the minimum amount of free stack which each
681 task has ever had available in the sysrq-T and sysrq-P debug output.
683 This option will slow down process creation somewhat.
685 config DEBUG_KOBJECT
686 bool "kobject debugging"
687 depends on DEBUG_KERNEL
688 help
689 If you say Y here, some extra kobject debugging messages will be sent
690 to the syslog.
692 config DEBUG_HIGHMEM
693 bool "Highmem debugging"
694 depends on DEBUG_KERNEL && HIGHMEM
695 help
696 This options enables addition error checking for high memory systems.
697 Disable for production systems.
699 config DEBUG_BUGVERBOSE
700 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
701 depends on BUG
702 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
703 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || TILE
704 default y
705 help
706 Say Y here to make BUG() panics output the file name and line number
707 of the BUG call as well as the EIP and oops trace. This aids
708 debugging but costs about 70-100K of memory.
710 config DEBUG_INFO
711 bool "Compile the kernel with debug info"
712 depends on DEBUG_KERNEL
713 help
714 If you say Y here the resulting kernel image will include
715 debugging info resulting in a larger kernel image.
716 This adds debug symbols to the kernel and modules (gcc -g), and
717 is needed if you intend to use kernel crashdump or binary object
718 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
719 Say Y here only if you plan to debug the kernel.
721 If unsure, say N.
723 config DEBUG_INFO_REDUCED
724 bool "Reduce debugging information"
725 depends on DEBUG_INFO
726 help
727 If you say Y here gcc is instructed to generate less debugging
728 information for structure types. This means that tools that
729 need full debugging information (like kgdb or systemtap) won't
730 be happy. But if you merely need debugging information to
731 resolve line numbers there is no loss. Advantage is that
732 build directory object sizes shrink dramatically over a full
733 DEBUG_INFO build and compile times are reduced too.
734 Only works with newer gcc versions.
736 config DEBUG_VM
737 bool "Debug VM"
738 depends on DEBUG_KERNEL
739 help
740 Enable this to turn on extended checks in the virtual-memory system
741 that may impact performance.
743 If unsure, say N.
745 config DEBUG_VIRTUAL
746 bool "Debug VM translations"
747 depends on DEBUG_KERNEL && X86
748 help
749 Enable some costly sanity checks in virtual to page code. This can
750 catch mistakes with virt_to_page() and friends.
752 If unsure, say N.
754 config DEBUG_NOMMU_REGIONS
755 bool "Debug the global anon/private NOMMU mapping region tree"
756 depends on DEBUG_KERNEL && !MMU
757 help
758 This option causes the global tree of anonymous and private mapping
759 regions to be regularly checked for invalid topology.
761 config DEBUG_WRITECOUNT
762 bool "Debug filesystem writers count"
763 depends on DEBUG_KERNEL
764 help
765 Enable this to catch wrong use of the writers count in struct
766 vfsmount. This will increase the size of each file struct by
767 32 bits.
769 If unsure, say N.
771 config DEBUG_MEMORY_INIT
772 bool "Debug memory initialisation" if EXPERT
773 default !EXPERT
774 help
775 Enable this for additional checks during memory initialisation.
776 The sanity checks verify aspects of the VM such as the memory model
777 and other information provided by the architecture. Verbose
778 information will be printed at KERN_DEBUG loglevel depending
779 on the mminit_loglevel= command-line option.
781 If unsure, say Y
783 config DEBUG_LIST
784 bool "Debug linked list manipulation"
785 depends on DEBUG_KERNEL
786 help
787 Enable this to turn on extended checks in the linked-list
788 walking routines.
790 If unsure, say N.
792 config TEST_LIST_SORT
793 bool "Linked list sorting test"
794 depends on DEBUG_KERNEL
795 help
796 Enable this to turn on 'list_sort()' function test. This test is
797 executed only once during system boot, so affects only boot time.
799 If unsure, say N.
801 config DEBUG_SG
802 bool "Debug SG table operations"
803 depends on DEBUG_KERNEL
804 help
805 Enable this to turn on checks on scatter-gather tables. This can
806 help find problems with drivers that do not properly initialize
807 their sg tables.
809 If unsure, say N.
811 config DEBUG_NOTIFIERS
812 bool "Debug notifier call chains"
813 depends on DEBUG_KERNEL
814 help
815 Enable this to turn on sanity checking for notifier call chains.
816 This is most useful for kernel developers to make sure that
817 modules properly unregister themselves from notifier chains.
818 This is a relatively cheap check but if you care about maximum
819 performance, say N.
821 config DEBUG_CREDENTIALS
822 bool "Debug credential management"
823 depends on DEBUG_KERNEL
824 help
825 Enable this to turn on some debug checking for credential
826 management. The additional code keeps track of the number of
827 pointers from task_structs to any given cred struct, and checks to
828 see that this number never exceeds the usage count of the cred
829 struct.
831 Furthermore, if SELinux is enabled, this also checks that the
832 security pointer in the cred struct is never seen to be invalid.
834 If unsure, say N.
836 #
837 # Select this config option from the architecture Kconfig, if it
838 # is preferred to always offer frame pointers as a config
839 # option on the architecture (regardless of KERNEL_DEBUG):
840 #
841 config ARCH_WANT_FRAME_POINTERS
842 bool
843 help
845 config FRAME_POINTER
846 bool "Compile the kernel with frame pointers"
847 depends on DEBUG_KERNEL && \
848 (CRIS || M68K || FRV || UML || \
849 AVR32 || SUPERH || BLACKFIN || MN10300) || \
850 ARCH_WANT_FRAME_POINTERS
851 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
852 help
853 If you say Y here the resulting kernel image will be slightly
854 larger and slower, but it gives very useful debugging information
855 in case of kernel bugs. (precise oopses/stacktraces/warnings)
857 config BOOT_PRINTK_DELAY
858 bool "Delay each boot printk message by N milliseconds"
859 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
860 help
861 This build option allows you to read kernel boot messages
862 by inserting a short delay after each one. The delay is
863 specified in milliseconds on the kernel command line,
864 using "boot_delay=N".
866 It is likely that you would also need to use "lpj=M" to preset
867 the "loops per jiffie" value.
868 See a previous boot log for the "lpj" value to use for your
869 system, and then set "lpj=M" before setting "boot_delay=N".
870 NOTE: Using this option may adversely affect SMP systems.
871 I.e., processors other than the first one may not boot up.
872 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
873 what it believes to be lockup conditions.
875 config RCU_TORTURE_TEST
876 tristate "torture tests for RCU"
877 depends on DEBUG_KERNEL
878 default n
879 help
880 This option provides a kernel module that runs torture tests
881 on the RCU infrastructure. The kernel module may be built
882 after the fact on the running kernel to be tested, if desired.
884 Say Y here if you want RCU torture tests to be built into
885 the kernel.
886 Say M if you want the RCU torture tests to build as a module.
887 Say N if you are unsure.
889 config RCU_TORTURE_TEST_RUNNABLE
890 bool "torture tests for RCU runnable by default"
891 depends on RCU_TORTURE_TEST = y
892 default n
893 help
894 This option provides a way to build the RCU torture tests
895 directly into the kernel without them starting up at boot
896 time. You can use /proc/sys/kernel/rcutorture_runnable
897 to manually override this setting. This /proc file is
898 available only when the RCU torture tests have been built
899 into the kernel.
901 Say Y here if you want the RCU torture tests to start during
902 boot (you probably don't).
903 Say N here if you want the RCU torture tests to start only
904 after being manually enabled via /proc.
906 config RCU_CPU_STALL_TIMEOUT
907 int "RCU CPU stall timeout in seconds"
908 depends on TREE_RCU || TREE_PREEMPT_RCU
909 range 3 300
910 default 60
911 help
912 If a given RCU grace period extends more than the specified
913 number of seconds, a CPU stall warning is printed. If the
914 RCU grace period persists, additional CPU stall warnings are
915 printed at more widely spaced intervals.
917 config RCU_CPU_STALL_VERBOSE
918 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
919 depends on TREE_PREEMPT_RCU
920 default y
921 help
922 This option causes RCU to printk detailed per-task information
923 for any tasks that are stalling the current RCU grace period.
925 Say N if you are unsure.
927 Say Y if you want to enable such checks.
929 config KPROBES_SANITY_TEST
930 bool "Kprobes sanity tests"
931 depends on DEBUG_KERNEL
932 depends on KPROBES
933 default n
934 help
935 This option provides for testing basic kprobes functionality on
936 boot. A sample kprobe, jprobe and kretprobe are inserted and
937 verified for functionality.
939 Say N if you are unsure.
941 config BACKTRACE_SELF_TEST
942 tristate "Self test for the backtrace code"
943 depends on DEBUG_KERNEL
944 default n
945 help
946 This option provides a kernel module that can be used to test
947 the kernel stack backtrace code. This option is not useful
948 for distributions or general kernels, but only for kernel
949 developers working on architecture code.
951 Note that if you want to also test saved backtraces, you will
952 have to enable STACKTRACE as well.
954 Say N if you are unsure.
956 config DEBUG_BLOCK_EXT_DEVT
957 bool "Force extended block device numbers and spread them"
958 depends on DEBUG_KERNEL
959 depends on BLOCK
960 default n
961 help
962 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
963 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
964 YOU ARE DOING. Distros, please enable this and fix whatever
965 is broken.
967 Conventionally, block device numbers are allocated from
968 predetermined contiguous area. However, extended block area
969 may introduce non-contiguous block device numbers. This
970 option forces most block device numbers to be allocated from
971 the extended space and spreads them to discover kernel or
972 userland code paths which assume predetermined contiguous
973 device number allocation.
975 Note that turning on this debug option shuffles all the
976 device numbers for all IDE and SCSI devices including libata
977 ones, so root partition specified using device number
978 directly (via rdev or root=MAJ:MIN) won't work anymore.
979 Textual device names (root=/dev/sdXn) will continue to work.
981 Say N if you are unsure.
983 config DEBUG_FORCE_WEAK_PER_CPU
984 bool "Force weak per-cpu definitions"
985 depends on DEBUG_KERNEL
986 help
987 s390 and alpha require percpu variables in modules to be
988 defined weak to work around addressing range issue which
989 puts the following two restrictions on percpu variable
990 definitions.
992 1. percpu symbols must be unique whether static or not
993 2. percpu variables can't be defined inside a function
995 To ensure that generic code follows the above rules, this
996 option forces all percpu variables to be defined as weak.
998 config DEBUG_PER_CPU_MAPS
999 bool "Debug access to per_cpu maps"
1000 depends on DEBUG_KERNEL
1001 depends on SMP
1002 help
1003 Say Y to verify that the per_cpu map being accessed has
1004 been set up. This adds a fair amount of code to kernel memory
1005 and decreases performance.
1007 Say N if unsure.
1009 config LKDTM
1010 tristate "Linux Kernel Dump Test Tool Module"
1011 depends on DEBUG_FS
1012 depends on BLOCK
1013 default n
1014 help
1015 This module enables testing of the different dumping mechanisms by
1016 inducing system failures at predefined crash points.
1017 If you don't need it: say N
1018 Choose M here to compile this code as a module. The module will be
1019 called lkdtm.
1021 Documentation on how to use the module can be found in
1022 Documentation/fault-injection/provoke-crashes.txt
1024 config CPU_NOTIFIER_ERROR_INJECT
1025 tristate "CPU notifier error injection module"
1026 depends on HOTPLUG_CPU && DEBUG_KERNEL
1027 help
1028 This option provides a kernel module that can be used to test
1029 the error handling of the cpu notifiers
1031 To compile this code as a module, choose M here: the module will
1032 be called cpu-notifier-error-inject.
1034 If unsure, say N.
1036 config FAULT_INJECTION
1037 bool "Fault-injection framework"
1038 depends on DEBUG_KERNEL
1039 help
1040 Provide fault-injection framework.
1041 For more details, see Documentation/fault-injection/.
1043 config FAILSLAB
1044 bool "Fault-injection capability for kmalloc"
1045 depends on FAULT_INJECTION
1046 depends on SLAB || SLUB
1047 help
1048 Provide fault-injection capability for kmalloc.
1050 config FAIL_PAGE_ALLOC
1051 bool "Fault-injection capabilitiy for alloc_pages()"
1052 depends on FAULT_INJECTION
1053 help
1054 Provide fault-injection capability for alloc_pages().
1056 config FAIL_MAKE_REQUEST
1057 bool "Fault-injection capability for disk IO"
1058 depends on FAULT_INJECTION && BLOCK
1059 help
1060 Provide fault-injection capability for disk IO.
1062 config FAIL_IO_TIMEOUT
1063 bool "Fault-injection capability for faking disk interrupts"
1064 depends on FAULT_INJECTION && BLOCK
1065 help
1066 Provide fault-injection capability on end IO handling. This
1067 will make the block layer "forget" an interrupt as configured,
1068 thus exercising the error handling.
1070 Only works with drivers that use the generic timeout handling,
1071 for others it wont do anything.
1073 config FAIL_MMC_REQUEST
1074 bool "Fault-injection capability for MMC IO"
1075 select DEBUG_FS
1076 depends on FAULT_INJECTION && MMC
1077 help
1078 Provide fault-injection capability for MMC IO.
1079 This will make the mmc core return data errors. This is
1080 useful to test the error handling in the mmc block device
1081 and to test how the mmc host driver handles retries from
1082 the block device.
1084 config FAULT_INJECTION_DEBUG_FS
1085 bool "Debugfs entries for fault-injection capabilities"
1086 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1087 help
1088 Enable configuration of fault-injection capabilities via debugfs.
1090 config FAULT_INJECTION_STACKTRACE_FILTER
1091 bool "stacktrace filter for fault-injection capabilities"
1092 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1093 depends on !X86_64
1094 select STACKTRACE
1095 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
1096 help
1097 Provide stacktrace filter for fault-injection capabilities
1099 config LATENCYTOP
1100 bool "Latency measuring infrastructure"
1101 depends on HAVE_LATENCYTOP_SUPPORT
1102 depends on DEBUG_KERNEL
1103 depends on STACKTRACE_SUPPORT
1104 depends on PROC_FS
1105 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
1106 select KALLSYMS
1107 select KALLSYMS_ALL
1108 select STACKTRACE
1109 select SCHEDSTATS
1110 select SCHED_DEBUG
1111 help
1112 Enable this option if you want to use the LatencyTOP tool
1113 to find out which userspace is blocking on what kernel operations.
1115 config SYSCTL_SYSCALL_CHECK
1116 bool "Sysctl checks"
1117 depends on SYSCTL
1118 ---help---
1119 sys_sysctl uses binary paths that have been found challenging
1120 to properly maintain and use. This enables checks that help
1121 you to keep things correct.
1123 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1124 bool
1126 config DEBUG_STRICT_USER_COPY_CHECKS
1127 bool "Strict user copy size checks"
1128 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1129 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1130 help
1131 Enabling this option turns a certain set of sanity checks for user
1132 copy operations into compile time failures.
1134 The copy_from_user() etc checks are there to help test if there
1135 are sufficient security checks on the length argument of
1136 the copy operation, by having gcc prove that the argument is
1137 within bounds.
1139 If unsure, say N.
1141 source mm/Kconfig.debug
1142 source kernel/trace/Kconfig
1144 config PROVIDE_OHCI1394_DMA_INIT
1145 bool "Remote debugging over FireWire early on boot"
1146 depends on PCI && X86
1147 help
1148 If you want to debug problems which hang or crash the kernel early
1149 on boot and the crashing machine has a FireWire port, you can use
1150 this feature to remotely access the memory of the crashed machine
1151 over FireWire. This employs remote DMA as part of the OHCI1394
1152 specification which is now the standard for FireWire controllers.
1154 With remote DMA, you can monitor the printk buffer remotely using
1155 firescope and access all memory below 4GB using fireproxy from gdb.
1156 Even controlling a kernel debugger is possible using remote DMA.
1158 Usage:
1160 If ohci1394_dma=early is used as boot parameter, it will initialize
1161 all OHCI1394 controllers which are found in the PCI config space.
1163 As all changes to the FireWire bus such as enabling and disabling
1164 devices cause a bus reset and thereby disable remote DMA for all
1165 devices, be sure to have the cable plugged and FireWire enabled on
1166 the debugging host before booting the debug target for debugging.
1168 This code (~1k) is freed after boot. By then, the firewire stack
1169 in charge of the OHCI-1394 controllers should be used instead.
1171 See Documentation/debugging-via-ohci1394.txt for more information.
1173 config FIREWIRE_OHCI_REMOTE_DMA
1174 bool "Remote debugging over FireWire with firewire-ohci"
1175 depends on FIREWIRE_OHCI
1176 help
1177 This option lets you use the FireWire bus for remote debugging
1178 with help of the firewire-ohci driver. It enables unfiltered
1179 remote DMA in firewire-ohci.
1180 See Documentation/debugging-via-ohci1394.txt for more information.
1182 If unsure, say N.
1184 config BUILD_DOCSRC
1185 bool "Build targets in Documentation/ tree"
1186 depends on HEADERS_CHECK
1187 help
1188 This option attempts to build objects from the source files in the
1189 kernel Documentation/ tree.
1191 Say N if you are unsure.
1193 config DYNAMIC_DEBUG
1194 bool "Enable dynamic printk() support"
1195 default n
1196 depends on PRINTK
1197 depends on DEBUG_FS
1198 help
1200 Compiles debug level messages into the kernel, which would not
1201 otherwise be available at runtime. These messages can then be
1202 enabled/disabled based on various levels of scope - per source file,
1203 function, module, format string, and line number. This mechanism
1204 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1205 this compile option is a larger kernel text size of about 2%.
1207 Usage:
1209 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1210 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1211 filesystem must first be mounted before making use of this feature.
1212 We refer the control file as: <debugfs>/dynamic_debug/control. This
1213 file contains a list of the debug statements that can be enabled. The
1214 format for each line of the file is:
1216 filename:lineno [module]function flags format
1218 filename : source file of the debug statement
1219 lineno : line number of the debug statement
1220 module : module that contains the debug statement
1221 function : function that contains the debug statement
1222 flags : 'p' means the line is turned 'on' for printing
1223 format : the format used for the debug statement
1225 From a live system:
1227 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1228 # filename:lineno [module]function flags format
1229 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1230 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1231 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1233 Example usage:
1235 // enable the message at line 1603 of file svcsock.c
1236 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1237 <debugfs>/dynamic_debug/control
1239 // enable all the messages in file svcsock.c
1240 nullarbor:~ # echo -n 'file svcsock.c +p' >
1241 <debugfs>/dynamic_debug/control
1243 // enable all the messages in the NFS server module
1244 nullarbor:~ # echo -n 'module nfsd +p' >
1245 <debugfs>/dynamic_debug/control
1247 // enable all 12 messages in the function svc_process()
1248 nullarbor:~ # echo -n 'func svc_process +p' >
1249 <debugfs>/dynamic_debug/control
1251 // disable all 12 messages in the function svc_process()
1252 nullarbor:~ # echo -n 'func svc_process -p' >
1253 <debugfs>/dynamic_debug/control
1255 See Documentation/dynamic-debug-howto.txt for additional information.
1257 config DMA_API_DEBUG
1258 bool "Enable debugging of DMA-API usage"
1259 depends on HAVE_DMA_API_DEBUG
1260 help
1261 Enable this option to debug the use of the DMA API by device drivers.
1262 With this option you will be able to detect common bugs in device
1263 drivers like double-freeing of DMA mappings or freeing mappings that
1264 were never allocated.
1265 This option causes a performance degredation. Use only if you want
1266 to debug device drivers. If unsure, say N.
1268 config ATOMIC64_SELFTEST
1269 bool "Perform an atomic64_t self-test at boot"
1270 help
1271 Enable this option to test the atomic64_t functions at boot.
1273 If unsure, say N.
1275 config ASYNC_RAID6_TEST
1276 tristate "Self test for hardware accelerated raid6 recovery"
1277 depends on ASYNC_RAID6_RECOV
1278 select ASYNC_MEMCPY
1279 ---help---
1280 This is a one-shot self test that permutes through the
1281 recovery of all the possible two disk failure scenarios for a
1282 N-disk array. Recovery is performed with the asynchronous
1283 raid6 recovery routines, and will optionally use an offload
1284 engine if one is available.
1286 If unsure, say N.
1288 source "samples/Kconfig"
1290 source "lib/Kconfig.kgdb"
1292 source "lib/Kconfig.kmemcheck"
1294 config TEST_KSTRTOX
1295 tristate "Test kstrto*() family of functions at runtime"