| blob | c768bcdda1b700331a991cad681c5c2d6862c419 |
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.
12 config DEFAULT_MESSAGE_LOGLEVEL
13 int "Default message log level (1-7)"
14 range 1 7
15 default "4"
16 help
17 Default log level for printk statements with no specified priority.
19 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
20 that are auditing their logs closely may want to set it to a lower
21 priority.
23 config ENABLE_WARN_DEPRECATED
24 bool "Enable __deprecated logic"
25 default y
26 help
27 Enable the __deprecated logic in the kernel build.
28 Disable this to suppress the "warning: 'foo' is deprecated
29 (declared at kernel/power/somefile.c:1234)" messages.
31 config ENABLE_MUST_CHECK
32 bool "Enable __must_check logic"
33 default y
34 help
35 Enable the __must_check logic in the kernel build. Disable this to
36 suppress the "warning: ignoring return value of 'foo', declared with
37 attribute warn_unused_result" messages.
39 config FRAME_WARN
40 int "Warn for stack frames larger than (needs gcc 4.4)"
41 range 0 8192
42 default 1024 if !64BIT
43 default 2048 if 64BIT
44 help
45 Tell gcc to warn at build time for stack frames larger than this.
46 Setting this too low will cause a lot of warnings.
47 Setting it to 0 disables the warning.
48 Requires gcc 4.4
50 config MAGIC_SYSRQ
51 bool "Magic SysRq key"
52 depends on !UML
53 help
54 If you say Y here, you will have some control over the system even
55 if the system crashes for example during kernel debugging (e.g., you
56 will be able to flush the buffer cache to disk, reboot the system
57 immediately or dump some status information). This is accomplished
58 by pressing various keys while holding SysRq (Alt+PrintScreen). It
59 also works on a serial console (on PC hardware at least), if you
60 send a BREAK and then within 5 seconds a command keypress. The
61 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
62 unless you really know what this hack does.
64 config STRIP_ASM_SYMS
65 bool "Strip assembler-generated symbols during link"
66 default n
67 help
68 Strip internal assembler-generated symbols during a link (symbols
69 that look like '.Lxxx') so they don't pollute the output of
70 get_wchan() and suchlike.
72 config UNUSED_SYMBOLS
73 bool "Enable unused/obsolete exported symbols"
74 default y if X86
75 help
76 Unused but exported symbols make the kernel needlessly bigger. For
77 that reason most of these unused exports will soon be removed. This
78 option is provided temporarily to provide a transition period in case
79 some external kernel module needs one of these symbols anyway. If you
80 encounter such a case in your module, consider if you are actually
81 using the right API. (rationale: since nobody in the kernel is using
82 this in a module, there is a pretty good chance it's actually the
83 wrong interface to use). If you really need the symbol, please send a
84 mail to the linux kernel mailing list mentioning the symbol and why
85 you really need it, and what the merge plan to the mainline kernel for
86 your module is.
88 config DEBUG_FS
89 bool "Debug Filesystem"
90 help
91 debugfs is a virtual file system that kernel developers use to put
92 debugging files into. Enable this option to be able to read and
93 write to these files.
95 For detailed documentation on the debugfs API, see
96 Documentation/DocBook/filesystems.
98 If unsure, say N.
100 config HEADERS_CHECK
101 bool "Run 'make headers_check' when building vmlinux"
102 depends on !UML
103 help
104 This option will extract the user-visible kernel headers whenever
105 building the kernel, and will run basic sanity checks on them to
106 ensure that exported files do not attempt to include files which
107 were not exported, etc.
109 If you're making modifications to header files which are
110 relevant for userspace, say 'Y', and check the headers
111 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
112 your build tree), to make sure they're suitable.
114 config DEBUG_SECTION_MISMATCH
115 bool "Enable full Section mismatch analysis"
116 help
117 The section mismatch analysis checks if there are illegal
118 references from one section to another section.
119 Linux will during link or during runtime drop some sections
120 and any use of code/data previously in these sections will
121 most likely result in an oops.
122 In the code functions and variables are annotated with
123 __init, __devinit etc. (see full list in include/linux/init.h)
124 which results in the code/data being placed in specific sections.
125 The section mismatch analysis is always done after a full
126 kernel build but enabling this option will in addition
127 do the following:
128 - Add the option -fno-inline-functions-called-once to gcc
129 When inlining a function annotated __init in a non-init
130 function we would lose the section information and thus
131 the analysis would not catch the illegal reference.
132 This option tells gcc to inline less but will also
133 result in a larger kernel.
134 - Run the section mismatch analysis for each module/built-in.o
135 When we run the section mismatch analysis on vmlinux.o we
136 lose valueble information about where the mismatch was
137 introduced.
138 Running the analysis for each module/built-in.o file
139 will tell where the mismatch happens much closer to the
140 source. The drawback is that we will report the same
141 mismatch at least twice.
142 - Enable verbose reporting from modpost to help solving
143 the section mismatches reported.
145 config DEBUG_KERNEL
146 bool "Kernel debugging"
147 help
148 Say Y here if you are developing drivers or trying to debug and
149 identify kernel problems.
151 config DEBUG_SHIRQ
152 bool "Debug shared IRQ handlers"
153 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
154 help
155 Enable this to generate a spurious interrupt as soon as a shared
156 interrupt handler is registered, and just before one is deregistered.
157 Drivers ought to be able to handle interrupts coming in at those
158 points; some don't and need to be caught.
160 config LOCKUP_DETECTOR
161 bool "Detect Hard and Soft Lockups"
162 depends on DEBUG_KERNEL && !S390
163 help
164 Say Y here to enable the kernel to act as a watchdog to detect
165 hard and soft lockups.
167 Softlockups are bugs that cause the kernel to loop in kernel
168 mode for more than 60 seconds, without giving other tasks a
169 chance to run. The current stack trace is displayed upon
170 detection and the system will stay locked up.
172 Hardlockups are bugs that cause the CPU to loop in kernel mode
173 for more than 60 seconds, without letting other interrupts have a
174 chance to run. The current stack trace is displayed upon detection
175 and the system will stay locked up.
177 The overhead should be minimal. A periodic hrtimer runs to
178 generate interrupts and kick the watchdog task every 10-12 seconds.
179 An NMI is generated every 60 seconds or so to check for hardlockups.
181 config HARDLOCKUP_DETECTOR
182 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
183 !ARCH_HAS_NMI_WATCHDOG
185 config BOOTPARAM_HARDLOCKUP_PANIC
186 bool "Panic (Reboot) On Hard Lockups"
187 depends on LOCKUP_DETECTOR
188 help
189 Say Y here to enable the kernel to panic on "hard lockups",
190 which are bugs that cause the kernel to loop in kernel
191 mode with interrupts disabled for more than 60 seconds.
193 Say N if unsure.
195 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
196 int
197 depends on LOCKUP_DETECTOR
198 range 0 1
199 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
200 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
202 config BOOTPARAM_SOFTLOCKUP_PANIC
203 bool "Panic (Reboot) On Soft Lockups"
204 depends on LOCKUP_DETECTOR
205 help
206 Say Y here to enable the kernel to panic on "soft lockups",
207 which are bugs that cause the kernel to loop in kernel
208 mode for more than 60 seconds, without giving other tasks a
209 chance to run.
211 The panic can be used in combination with panic_timeout,
212 to cause the system to reboot automatically after a
213 lockup has been detected. This feature is useful for
214 high-availability systems that have uptime guarantees and
215 where a lockup must be resolved ASAP.
217 Say N if unsure.
219 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
220 int
221 depends on LOCKUP_DETECTOR
222 range 0 1
223 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
224 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
226 config DETECT_HUNG_TASK
227 bool "Detect Hung Tasks"
228 depends on DEBUG_KERNEL
229 default DETECT_SOFTLOCKUP
230 help
231 Say Y here to enable the kernel to detect "hung tasks",
232 which are bugs that cause the task to be stuck in
233 uninterruptible "D" state indefinitiley.
235 When a hung task is detected, the kernel will print the
236 current stack trace (which you should report), but the
237 task will stay in uninterruptible state. If lockdep is
238 enabled then all held locks will also be reported. This
239 feature has negligible overhead.
241 config BOOTPARAM_HUNG_TASK_PANIC
242 bool "Panic (Reboot) On Hung Tasks"
243 depends on DETECT_HUNG_TASK
244 help
245 Say Y here to enable the kernel to panic on "hung tasks",
246 which are bugs that cause the kernel to leave a task stuck
247 in uninterruptible "D" state.
249 The panic can be used in combination with panic_timeout,
250 to cause the system to reboot automatically after a
251 hung task has been detected. This feature is useful for
252 high-availability systems that have uptime guarantees and
253 where a hung tasks must be resolved ASAP.
255 Say N if unsure.
257 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
258 int
259 depends on DETECT_HUNG_TASK
260 range 0 1
261 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
262 default 1 if BOOTPARAM_HUNG_TASK_PANIC
264 config SCHED_DEBUG
265 bool "Collect scheduler debugging info"
266 depends on DEBUG_KERNEL && PROC_FS
267 default y
268 help
269 If you say Y here, the /proc/sched_debug file will be provided
270 that can help debug the scheduler. The runtime overhead of this
271 option is minimal.
273 config SCHEDSTATS
274 bool "Collect scheduler statistics"
275 depends on DEBUG_KERNEL && PROC_FS
276 help
277 If you say Y here, additional code will be inserted into the
278 scheduler and related routines to collect statistics about
279 scheduler behavior and provide them in /proc/schedstat. These
280 stats may be useful for both tuning and debugging the scheduler
281 If you aren't debugging the scheduler or trying to tune a specific
282 application, you can say N to avoid the very slight overhead
283 this adds.
285 config TIMER_STATS
286 bool "Collect kernel timers statistics"
287 depends on DEBUG_KERNEL && PROC_FS
288 help
289 If you say Y here, additional code will be inserted into the
290 timer routines to collect statistics about kernel timers being
291 reprogrammed. The statistics can be read from /proc/timer_stats.
292 The statistics collection is started by writing 1 to /proc/timer_stats,
293 writing 0 stops it. This feature is useful to collect information
294 about timer usage patterns in kernel and userspace. This feature
295 is lightweight if enabled in the kernel config but not activated
296 (it defaults to deactivated on bootup and will only be activated
297 if some application like powertop activates it explicitly).
299 config DEBUG_OBJECTS
300 bool "Debug object operations"
301 depends on DEBUG_KERNEL
302 help
303 If you say Y here, additional code will be inserted into the
304 kernel to track the life time of various objects and validate
305 the operations on those objects.
307 config DEBUG_OBJECTS_SELFTEST
308 bool "Debug objects selftest"
309 depends on DEBUG_OBJECTS
310 help
311 This enables the selftest of the object debug code.
313 config DEBUG_OBJECTS_FREE
314 bool "Debug objects in freed memory"
315 depends on DEBUG_OBJECTS
316 help
317 This enables checks whether a k/v free operation frees an area
318 which contains an object which has not been deactivated
319 properly. This can make kmalloc/kfree-intensive workloads
320 much slower.
322 config DEBUG_OBJECTS_TIMERS
323 bool "Debug timer objects"
324 depends on DEBUG_OBJECTS
325 help
326 If you say Y here, additional code will be inserted into the
327 timer routines to track the life time of timer objects and
328 validate the timer operations.
330 config DEBUG_OBJECTS_WORK
331 bool "Debug work objects"
332 depends on DEBUG_OBJECTS
333 help
334 If you say Y here, additional code will be inserted into the
335 work queue routines to track the life time of work objects and
336 validate the work operations.
338 config DEBUG_OBJECTS_RCU_HEAD
339 bool "Debug RCU callbacks objects"
340 depends on DEBUG_OBJECTS && PREEMPT
341 help
342 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
344 config DEBUG_OBJECTS_PERCPU_COUNTER
345 bool "Debug percpu counter objects"
346 depends on DEBUG_OBJECTS
347 help
348 If you say Y here, additional code will be inserted into the
349 percpu counter routines to track the life time of percpu counter
350 objects and validate the percpu counter operations.
352 config DEBUG_OBJECTS_ENABLE_DEFAULT
353 int "debug_objects bootup default value (0-1)"
354 range 0 1
355 default "1"
356 depends on DEBUG_OBJECTS
357 help
358 Debug objects boot parameter default value
360 config DEBUG_SLAB
361 bool "Debug slab memory allocations"
362 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
363 help
364 Say Y here to have the kernel do limited verification on memory
365 allocation as well as poisoning memory on free to catch use of freed
366 memory. This can make kmalloc/kfree-intensive workloads much slower.
368 config DEBUG_SLAB_LEAK
369 bool "Memory leak debugging"
370 depends on DEBUG_SLAB
372 config SLUB_DEBUG_ON
373 bool "SLUB debugging on by default"
374 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
375 default n
376 help
377 Boot with debugging on by default. SLUB boots by default with
378 the runtime debug capabilities switched off. Enabling this is
379 equivalent to specifying the "slub_debug" parameter on boot.
380 There is no support for more fine grained debug control like
381 possible with slub_debug=xxx. SLUB debugging may be switched
382 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
383 "slub_debug=-".
385 config SLUB_STATS
386 default n
387 bool "Enable SLUB performance statistics"
388 depends on SLUB && SYSFS
389 help
390 SLUB statistics are useful to debug SLUBs allocation behavior in
391 order find ways to optimize the allocator. This should never be
392 enabled for production use since keeping statistics slows down
393 the allocator by a few percentage points. The slabinfo command
394 supports the determination of the most active slabs to figure
395 out which slabs are relevant to a particular load.
396 Try running: slabinfo -DA
398 config DEBUG_KMEMLEAK
399 bool "Kernel memory leak detector"
400 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
401 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
403 select DEBUG_FS if SYSFS
404 select STACKTRACE if STACKTRACE_SUPPORT
405 select KALLSYMS
406 select CRC32
407 help
408 Say Y here if you want to enable the memory leak
409 detector. The memory allocation/freeing is traced in a way
410 similar to the Boehm's conservative garbage collector, the
411 difference being that the orphan objects are not freed but
412 only shown in /sys/kernel/debug/kmemleak. Enabling this
413 feature will introduce an overhead to memory
414 allocations. See Documentation/kmemleak.txt for more
415 details.
417 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
418 of finding leaks due to the slab objects poisoning.
420 In order to access the kmemleak file, debugfs needs to be
421 mounted (usually at /sys/kernel/debug).
423 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
424 int "Maximum kmemleak early log entries"
425 depends on DEBUG_KMEMLEAK
426 range 200 40000
427 default 400
428 help
429 Kmemleak must track all the memory allocations to avoid
430 reporting false positives. Since memory may be allocated or
431 freed before kmemleak is initialised, an early log buffer is
432 used to store these actions. If kmemleak reports "early log
433 buffer exceeded", please increase this value.
435 config DEBUG_KMEMLEAK_TEST
436 tristate "Simple test for the kernel memory leak detector"
437 depends on DEBUG_KMEMLEAK && m
438 help
439 This option enables a module that explicitly leaks memory.
441 If unsure, say N.
443 config DEBUG_KMEMLEAK_DEFAULT_OFF
444 bool "Default kmemleak to off"
445 depends on DEBUG_KMEMLEAK
446 help
447 Say Y here to disable kmemleak by default. It can then be enabled
448 on the command line via kmemleak=on.
450 config DEBUG_PREEMPT
451 bool "Debug preemptible kernel"
452 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
453 default y
454 help
455 If you say Y here then the kernel will use a debug variant of the
456 commonly used smp_processor_id() function and will print warnings
457 if kernel code uses it in a preemption-unsafe way. Also, the kernel
458 will detect preemption count underflows.
460 config DEBUG_RT_MUTEXES
461 bool "RT Mutex debugging, deadlock detection"
462 depends on DEBUG_KERNEL && RT_MUTEXES
463 help
464 This allows rt mutex semantics violations and rt mutex related
465 deadlocks (lockups) to be detected and reported automatically.
467 config DEBUG_PI_LIST
468 bool
469 default y
470 depends on DEBUG_RT_MUTEXES
472 config RT_MUTEX_TESTER
473 bool "Built-in scriptable tester for rt-mutexes"
474 depends on DEBUG_KERNEL && RT_MUTEXES
475 help
476 This option enables a rt-mutex tester.
478 config DEBUG_SPINLOCK
479 bool "Spinlock and rw-lock debugging: basic checks"
480 depends on DEBUG_KERNEL
481 help
482 Say Y here and build SMP to catch missing spinlock initialization
483 and certain other kinds of spinlock errors commonly made. This is
484 best used in conjunction with the NMI watchdog so that spinlock
485 deadlocks are also debuggable.
487 config DEBUG_MUTEXES
488 bool "Mutex debugging: basic checks"
489 depends on DEBUG_KERNEL
490 help
491 This feature allows mutex semantics violations to be detected and
492 reported.
494 config DEBUG_LOCK_ALLOC
495 bool "Lock debugging: detect incorrect freeing of live locks"
496 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
497 select DEBUG_SPINLOCK
498 select DEBUG_MUTEXES
499 select LOCKDEP
500 help
501 This feature will check whether any held lock (spinlock, rwlock,
502 mutex or rwsem) is incorrectly freed by the kernel, via any of the
503 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
504 vfree(), etc.), whether a live lock is incorrectly reinitialized via
505 spin_lock_init()/mutex_init()/etc., or whether there is any lock
506 held during task exit.
508 config PROVE_LOCKING
509 bool "Lock debugging: prove locking correctness"
510 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
511 select LOCKDEP
512 select DEBUG_SPINLOCK
513 select DEBUG_MUTEXES
514 select DEBUG_LOCK_ALLOC
515 select TRACE_IRQFLAGS
516 default n
517 help
518 This feature enables the kernel to prove that all locking
519 that occurs in the kernel runtime is mathematically
520 correct: that under no circumstance could an arbitrary (and
521 not yet triggered) combination of observed locking
522 sequences (on an arbitrary number of CPUs, running an
523 arbitrary number of tasks and interrupt contexts) cause a
524 deadlock.
526 In short, this feature enables the kernel to report locking
527 related deadlocks before they actually occur.
529 The proof does not depend on how hard and complex a
530 deadlock scenario would be to trigger: how many
531 participant CPUs, tasks and irq-contexts would be needed
532 for it to trigger. The proof also does not depend on
533 timing: if a race and a resulting deadlock is possible
534 theoretically (no matter how unlikely the race scenario
535 is), it will be proven so and will immediately be
536 reported by the kernel (once the event is observed that
537 makes the deadlock theoretically possible).
539 If a deadlock is impossible (i.e. the locking rules, as
540 observed by the kernel, are mathematically correct), the
541 kernel reports nothing.
543 NOTE: this feature can also be enabled for rwlocks, mutexes
544 and rwsems - in which case all dependencies between these
545 different locking variants are observed and mapped too, and
546 the proof of observed correctness is also maintained for an
547 arbitrary combination of these separate locking variants.
549 For more details, see Documentation/lockdep-design.txt.
551 config PROVE_RCU
552 bool "RCU debugging: prove RCU correctness"
553 depends on PROVE_LOCKING
554 default n
555 help
556 This feature enables lockdep extensions that check for correct
557 use of RCU APIs. This is currently under development. Say Y
558 if you want to debug RCU usage or help work on the PROVE_RCU
559 feature.
561 Say N if you are unsure.
563 config PROVE_RCU_REPEATEDLY
564 bool "RCU debugging: don't disable PROVE_RCU on first splat"
565 depends on PROVE_RCU
566 default n
567 help
568 By itself, PROVE_RCU will disable checking upon issuing the
569 first warning (or "splat"). This feature prevents such
570 disabling, allowing multiple RCU-lockdep warnings to be printed
571 on a single reboot.
573 Say Y to allow multiple RCU-lockdep warnings per boot.
575 Say N if you are unsure.
577 config SPARSE_RCU_POINTER
578 bool "RCU debugging: sparse-based checks for pointer usage"
579 default n
580 help
581 This feature enables the __rcu sparse annotation for
582 RCU-protected pointers. This annotation will cause sparse
583 to flag any non-RCU used of annotated pointers. This can be
584 helpful when debugging RCU usage. Please note that this feature
585 is not intended to enforce code cleanliness; it is instead merely
586 a debugging aid.
588 Say Y to make sparse flag questionable use of RCU-protected pointers
590 Say N if you are unsure.
592 config LOCKDEP
593 bool
594 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
595 select STACKTRACE
596 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
597 select KALLSYMS
598 select KALLSYMS_ALL
600 config LOCK_STAT
601 bool "Lock usage statistics"
602 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
603 select LOCKDEP
604 select DEBUG_SPINLOCK
605 select DEBUG_MUTEXES
606 select DEBUG_LOCK_ALLOC
607 default n
608 help
609 This feature enables tracking lock contention points
611 For more details, see Documentation/lockstat.txt
613 This also enables lock events required by "perf lock",
614 subcommand of perf.
615 If you want to use "perf lock", you also need to turn on
616 CONFIG_EVENT_TRACING.
618 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
619 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
621 config DEBUG_LOCKDEP
622 bool "Lock dependency engine debugging"
623 depends on DEBUG_KERNEL && LOCKDEP
624 help
625 If you say Y here, the lock dependency engine will do
626 additional runtime checks to debug itself, at the price
627 of more runtime overhead.
629 config TRACE_IRQFLAGS
630 bool
631 help
632 Enables hooks to interrupt enabling and disabling for
633 either tracing or lock debugging.
635 config DEBUG_SPINLOCK_SLEEP
636 bool "Spinlock debugging: sleep-inside-spinlock checking"
637 depends on DEBUG_KERNEL
638 help
639 If you say Y here, various routines which may sleep will become very
640 noisy if they are called with a spinlock held.
642 config DEBUG_LOCKING_API_SELFTESTS
643 bool "Locking API boot-time self-tests"
644 depends on DEBUG_KERNEL
645 help
646 Say Y here if you want the kernel to run a short self-test during
647 bootup. The self-test checks whether common types of locking bugs
648 are detected by debugging mechanisms or not. (if you disable
649 lock debugging then those bugs wont be detected of course.)
650 The following locking APIs are covered: spinlocks, rwlocks,
651 mutexes and rwsems.
653 config STACKTRACE
654 bool
655 depends on STACKTRACE_SUPPORT
657 config DEBUG_KOBJECT
658 bool "kobject debugging"
659 depends on DEBUG_KERNEL
660 help
661 If you say Y here, some extra kobject debugging messages will be sent
662 to the syslog.
664 config DEBUG_HIGHMEM
665 bool "Highmem debugging"
666 depends on DEBUG_KERNEL && HIGHMEM
667 help
668 This options enables addition error checking for high memory systems.
669 Disable for production systems.
671 config DEBUG_BUGVERBOSE
672 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
673 depends on BUG
674 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
675 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
676 default y
677 help
678 Say Y here to make BUG() panics output the file name and line number
679 of the BUG call as well as the EIP and oops trace. This aids
680 debugging but costs about 70-100K of memory.
682 config DEBUG_INFO
683 bool "Compile the kernel with debug info"
684 depends on DEBUG_KERNEL
685 help
686 If you say Y here the resulting kernel image will include
687 debugging info resulting in a larger kernel image.
688 This adds debug symbols to the kernel and modules (gcc -g), and
689 is needed if you intend to use kernel crashdump or binary object
690 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
691 Say Y here only if you plan to debug the kernel.
693 If unsure, say N.
695 config DEBUG_INFO_REDUCED
696 bool "Reduce debugging information"
697 depends on DEBUG_INFO
698 help
699 If you say Y here gcc is instructed to generate less debugging
700 information for structure types. This means that tools that
701 need full debugging information (like kgdb or systemtap) won't
702 be happy. But if you merely need debugging information to
703 resolve line numbers there is no loss. Advantage is that
704 build directory object sizes shrink dramatically over a full
705 DEBUG_INFO build and compile times are reduced too.
706 Only works with newer gcc versions.
708 config DEBUG_VM
709 bool "Debug VM"
710 depends on DEBUG_KERNEL
711 help
712 Enable this to turn on extended checks in the virtual-memory system
713 that may impact performance.
715 If unsure, say N.
717 config DEBUG_VIRTUAL
718 bool "Debug VM translations"
719 depends on DEBUG_KERNEL && X86
720 help
721 Enable some costly sanity checks in virtual to page code. This can
722 catch mistakes with virt_to_page() and friends.
724 If unsure, say N.
726 config DEBUG_NOMMU_REGIONS
727 bool "Debug the global anon/private NOMMU mapping region tree"
728 depends on DEBUG_KERNEL && !MMU
729 help
730 This option causes the global tree of anonymous and private mapping
731 regions to be regularly checked for invalid topology.
733 config DEBUG_WRITECOUNT
734 bool "Debug filesystem writers count"
735 depends on DEBUG_KERNEL
736 help
737 Enable this to catch wrong use of the writers count in struct
738 vfsmount. This will increase the size of each file struct by
739 32 bits.
741 If unsure, say N.
743 config DEBUG_MEMORY_INIT
744 bool "Debug memory initialisation" if EXPERT
745 default !EXPERT
746 help
747 Enable this for additional checks during memory initialisation.
748 The sanity checks verify aspects of the VM such as the memory model
749 and other information provided by the architecture. Verbose
750 information will be printed at KERN_DEBUG loglevel depending
751 on the mminit_loglevel= command-line option.
753 If unsure, say Y
755 config DEBUG_LIST
756 bool "Debug linked list manipulation"
757 depends on DEBUG_KERNEL
758 help
759 Enable this to turn on extended checks in the linked-list
760 walking routines.
762 If unsure, say N.
764 config TEST_LIST_SORT
765 bool "Linked list sorting test"
766 depends on DEBUG_KERNEL
767 help
768 Enable this to turn on 'list_sort()' function test. This test is
769 executed only once during system boot, so affects only boot time.
771 If unsure, say N.
773 config DEBUG_SG
774 bool "Debug SG table operations"
775 depends on DEBUG_KERNEL
776 help
777 Enable this to turn on checks on scatter-gather tables. This can
778 help find problems with drivers that do not properly initialize
779 their sg tables.
781 If unsure, say N.
783 config DEBUG_NOTIFIERS
784 bool "Debug notifier call chains"
785 depends on DEBUG_KERNEL
786 help
787 Enable this to turn on sanity checking for notifier call chains.
788 This is most useful for kernel developers to make sure that
789 modules properly unregister themselves from notifier chains.
790 This is a relatively cheap check but if you care about maximum
791 performance, say N.
793 config DEBUG_CREDENTIALS
794 bool "Debug credential management"
795 depends on DEBUG_KERNEL
796 help
797 Enable this to turn on some debug checking for credential
798 management. The additional code keeps track of the number of
799 pointers from task_structs to any given cred struct, and checks to
800 see that this number never exceeds the usage count of the cred
801 struct.
803 Furthermore, if SELinux is enabled, this also checks that the
804 security pointer in the cred struct is never seen to be invalid.
806 If unsure, say N.
808 #
809 # Select this config option from the architecture Kconfig, if it
810 # it is preferred to always offer frame pointers as a config
811 # option on the architecture (regardless of KERNEL_DEBUG):
812 #
813 config ARCH_WANT_FRAME_POINTERS
814 bool
815 help
817 config FRAME_POINTER
818 bool "Compile the kernel with frame pointers"
819 depends on DEBUG_KERNEL && \
820 (CRIS || M68K || FRV || UML || \
821 AVR32 || SUPERH || BLACKFIN || MN10300) || \
822 ARCH_WANT_FRAME_POINTERS
823 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
824 help
825 If you say Y here the resulting kernel image will be slightly
826 larger and slower, but it gives very useful debugging information
827 in case of kernel bugs. (precise oopses/stacktraces/warnings)
829 config BOOT_PRINTK_DELAY
830 bool "Delay each boot printk message by N milliseconds"
831 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
832 help
833 This build option allows you to read kernel boot messages
834 by inserting a short delay after each one. The delay is
835 specified in milliseconds on the kernel command line,
836 using "boot_delay=N".
838 It is likely that you would also need to use "lpj=M" to preset
839 the "loops per jiffie" value.
840 See a previous boot log for the "lpj" value to use for your
841 system, and then set "lpj=M" before setting "boot_delay=N".
842 NOTE: Using this option may adversely affect SMP systems.
843 I.e., processors other than the first one may not boot up.
844 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
845 what it believes to be lockup conditions.
847 config RCU_TORTURE_TEST
848 tristate "torture tests for RCU"
849 depends on DEBUG_KERNEL
850 default n
851 help
852 This option provides a kernel module that runs torture tests
853 on the RCU infrastructure. The kernel module may be built
854 after the fact on the running kernel to be tested, if desired.
856 Say Y here if you want RCU torture tests to be built into
857 the kernel.
858 Say M if you want the RCU torture tests to build as a module.
859 Say N if you are unsure.
861 config RCU_TORTURE_TEST_RUNNABLE
862 bool "torture tests for RCU runnable by default"
863 depends on RCU_TORTURE_TEST = y
864 default n
865 help
866 This option provides a way to build the RCU torture tests
867 directly into the kernel without them starting up at boot
868 time. You can use /proc/sys/kernel/rcutorture_runnable
869 to manually override this setting. This /proc file is
870 available only when the RCU torture tests have been built
871 into the kernel.
873 Say Y here if you want the RCU torture tests to start during
874 boot (you probably don't).
875 Say N here if you want the RCU torture tests to start only
876 after being manually enabled via /proc.
878 config RCU_CPU_STALL_DETECTOR
879 bool "Check for stalled CPUs delaying RCU grace periods"
880 depends on TREE_RCU || TREE_PREEMPT_RCU
881 default y
882 help
883 This option causes RCU to printk information on which
884 CPUs are delaying the current grace period, but only when
885 the grace period extends for excessive time periods.
887 Say N if you want to disable such checks.
889 Say Y if you are unsure.
891 config RCU_CPU_STALL_TIMEOUT
892 int "RCU CPU stall timeout in seconds"
893 depends on RCU_CPU_STALL_DETECTOR
894 range 3 300
895 default 60
896 help
897 If a given RCU grace period extends more than the specified
898 number of seconds, a CPU stall warning is printed. If the
899 RCU grace period persists, additional CPU stall warnings are
900 printed at more widely spaced intervals.
902 config RCU_CPU_STALL_DETECTOR_RUNNABLE
903 bool "RCU CPU stall checking starts automatically at boot"
904 depends on RCU_CPU_STALL_DETECTOR
905 default y
906 help
907 If set, start checking for RCU CPU stalls immediately on
908 boot. Otherwise, RCU CPU stall checking must be manually
909 enabled.
911 Say Y if you are unsure.
913 Say N if you wish to suppress RCU CPU stall checking during boot.
915 config RCU_CPU_STALL_VERBOSE
916 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
917 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
918 default y
919 help
920 This option causes RCU to printk detailed per-task information
921 for any tasks that are stalling the current RCU grace period.
923 Say N if you are unsure.
925 Say Y if you want to enable such checks.
927 config KPROBES_SANITY_TEST
928 bool "Kprobes sanity tests"
929 depends on DEBUG_KERNEL
930 depends on KPROBES
931 default n
932 help
933 This option provides for testing basic kprobes functionality on
934 boot. A sample kprobe, jprobe and kretprobe are inserted and
935 verified for functionality.
937 Say N if you are unsure.
939 config BACKTRACE_SELF_TEST
940 tristate "Self test for the backtrace code"
941 depends on DEBUG_KERNEL
942 default n
943 help
944 This option provides a kernel module that can be used to test
945 the kernel stack backtrace code. This option is not useful
946 for distributions or general kernels, but only for kernel
947 developers working on architecture code.
949 Note that if you want to also test saved backtraces, you will
950 have to enable STACKTRACE as well.
952 Say N if you are unsure.
954 config DEBUG_BLOCK_EXT_DEVT
955 bool "Force extended block device numbers and spread them"
956 depends on DEBUG_KERNEL
957 depends on BLOCK
958 default n
959 help
960 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
961 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
962 YOU ARE DOING. Distros, please enable this and fix whatever
963 is broken.
965 Conventionally, block device numbers are allocated from
966 predetermined contiguous area. However, extended block area
967 may introduce non-contiguous block device numbers. This
968 option forces most block device numbers to be allocated from
969 the extended space and spreads them to discover kernel or
970 userland code paths which assume predetermined contiguous
971 device number allocation.
973 Note that turning on this debug option shuffles all the
974 device numbers for all IDE and SCSI devices including libata
975 ones, so root partition specified using device number
976 directly (via rdev or root=MAJ:MIN) won't work anymore.
977 Textual device names (root=/dev/sdXn) will continue to work.
979 Say N if you are unsure.
981 config DEBUG_FORCE_WEAK_PER_CPU
982 bool "Force weak per-cpu definitions"
983 depends on DEBUG_KERNEL
984 help
985 s390 and alpha require percpu variables in modules to be
986 defined weak to work around addressing range issue which
987 puts the following two restrictions on percpu variable
988 definitions.
990 1. percpu symbols must be unique whether static or not
991 2. percpu variables can't be defined inside a function
993 To ensure that generic code follows the above rules, this
994 option forces all percpu variables to be defined as weak.
996 config LKDTM
997 tristate "Linux Kernel Dump Test Tool Module"
998 depends on DEBUG_FS
999 depends on BLOCK
1000 default n
1001 help
1002 This module enables testing of the different dumping mechanisms by
1003 inducing system failures at predefined crash points.
1004 If you don't need it: say N
1005 Choose M here to compile this code as a module. The module will be
1006 called lkdtm.
1008 Documentation on how to use the module can be found in
1009 Documentation/fault-injection/provoke-crashes.txt
1011 config CPU_NOTIFIER_ERROR_INJECT
1012 tristate "CPU notifier error injection module"
1013 depends on HOTPLUG_CPU && DEBUG_KERNEL
1014 help
1015 This option provides a kernel module that can be used to test
1016 the error handling of the cpu notifiers
1018 To compile this code as a module, choose M here: the module will
1019 be called cpu-notifier-error-inject.
1021 If unsure, say N.
1023 config FAULT_INJECTION
1024 bool "Fault-injection framework"
1025 depends on DEBUG_KERNEL
1026 help
1027 Provide fault-injection framework.
1028 For more details, see Documentation/fault-injection/.
1030 config FAILSLAB
1031 bool "Fault-injection capability for kmalloc"
1032 depends on FAULT_INJECTION
1033 depends on SLAB || SLUB
1034 help
1035 Provide fault-injection capability for kmalloc.
1037 config FAIL_PAGE_ALLOC
1038 bool "Fault-injection capabilitiy for alloc_pages()"
1039 depends on FAULT_INJECTION
1040 help
1041 Provide fault-injection capability for alloc_pages().
1043 config FAIL_MAKE_REQUEST
1044 bool "Fault-injection capability for disk IO"
1045 depends on FAULT_INJECTION && BLOCK
1046 help
1047 Provide fault-injection capability for disk IO.
1049 config FAIL_IO_TIMEOUT
1050 bool "Fault-injection capability for faking disk interrupts"
1051 depends on FAULT_INJECTION && BLOCK
1052 help
1053 Provide fault-injection capability on end IO handling. This
1054 will make the block layer "forget" an interrupt as configured,
1055 thus exercising the error handling.
1057 Only works with drivers that use the generic timeout handling,
1058 for others it wont do anything.
1060 config FAULT_INJECTION_DEBUG_FS
1061 bool "Debugfs entries for fault-injection capabilities"
1062 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1063 help
1064 Enable configuration of fault-injection capabilities via debugfs.
1066 config FAULT_INJECTION_STACKTRACE_FILTER
1067 bool "stacktrace filter for fault-injection capabilities"
1068 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1069 depends on !X86_64
1070 select STACKTRACE
1071 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
1072 help
1073 Provide stacktrace filter for fault-injection capabilities
1075 config LATENCYTOP
1076 bool "Latency measuring infrastructure"
1077 depends on HAVE_LATENCYTOP_SUPPORT
1078 depends on DEBUG_KERNEL
1079 depends on STACKTRACE_SUPPORT
1080 depends on PROC_FS
1081 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
1082 select KALLSYMS
1083 select KALLSYMS_ALL
1084 select STACKTRACE
1085 select SCHEDSTATS
1086 select SCHED_DEBUG
1087 help
1088 Enable this option if you want to use the LatencyTOP tool
1089 to find out which userspace is blocking on what kernel operations.
1091 config SYSCTL_SYSCALL_CHECK
1092 bool "Sysctl checks"
1093 depends on SYSCTL
1094 ---help---
1095 sys_sysctl uses binary paths that have been found challenging
1096 to properly maintain and use. This enables checks that help
1097 you to keep things correct.
1099 source mm/Kconfig.debug
1100 source kernel/trace/Kconfig
1102 config PROVIDE_OHCI1394_DMA_INIT
1103 bool "Remote debugging over FireWire early on boot"
1104 depends on PCI && X86
1105 help
1106 If you want to debug problems which hang or crash the kernel early
1107 on boot and the crashing machine has a FireWire port, you can use
1108 this feature to remotely access the memory of the crashed machine
1109 over FireWire. This employs remote DMA as part of the OHCI1394
1110 specification which is now the standard for FireWire controllers.
1112 With remote DMA, you can monitor the printk buffer remotely using
1113 firescope and access all memory below 4GB using fireproxy from gdb.
1114 Even controlling a kernel debugger is possible using remote DMA.
1116 Usage:
1118 If ohci1394_dma=early is used as boot parameter, it will initialize
1119 all OHCI1394 controllers which are found in the PCI config space.
1121 As all changes to the FireWire bus such as enabling and disabling
1122 devices cause a bus reset and thereby disable remote DMA for all
1123 devices, be sure to have the cable plugged and FireWire enabled on
1124 the debugging host before booting the debug target for debugging.
1126 This code (~1k) is freed after boot. By then, the firewire stack
1127 in charge of the OHCI-1394 controllers should be used instead.
1129 See Documentation/debugging-via-ohci1394.txt for more information.
1131 config FIREWIRE_OHCI_REMOTE_DMA
1132 bool "Remote debugging over FireWire with firewire-ohci"
1133 depends on FIREWIRE_OHCI
1134 help
1135 This option lets you use the FireWire bus for remote debugging
1136 with help of the firewire-ohci driver. It enables unfiltered
1137 remote DMA in firewire-ohci.
1138 See Documentation/debugging-via-ohci1394.txt for more information.
1140 If unsure, say N.
1142 config BUILD_DOCSRC
1143 bool "Build targets in Documentation/ tree"
1144 depends on HEADERS_CHECK
1145 help
1146 This option attempts to build objects from the source files in the
1147 kernel Documentation/ tree.
1149 Say N if you are unsure.
1151 config DYNAMIC_DEBUG
1152 bool "Enable dynamic printk() support"
1153 default n
1154 depends on PRINTK
1155 depends on DEBUG_FS
1156 help
1158 Compiles debug level messages into the kernel, which would not
1159 otherwise be available at runtime. These messages can then be
1160 enabled/disabled based on various levels of scope - per source file,
1161 function, module, format string, and line number. This mechanism
1162 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1163 this compile option is a larger kernel text size of about 2%.
1165 Usage:
1167 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1168 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1169 filesystem must first be mounted before making use of this feature.
1170 We refer the control file as: <debugfs>/dynamic_debug/control. This
1171 file contains a list of the debug statements that can be enabled. The
1172 format for each line of the file is:
1174 filename:lineno [module]function flags format
1176 filename : source file of the debug statement
1177 lineno : line number of the debug statement
1178 module : module that contains the debug statement
1179 function : function that contains the debug statement
1180 flags : 'p' means the line is turned 'on' for printing
1181 format : the format used for the debug statement
1183 From a live system:
1185 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1186 # filename:lineno [module]function flags format
1187 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1188 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1189 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1191 Example usage:
1193 // enable the message at line 1603 of file svcsock.c
1194 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1195 <debugfs>/dynamic_debug/control
1197 // enable all the messages in file svcsock.c
1198 nullarbor:~ # echo -n 'file svcsock.c +p' >
1199 <debugfs>/dynamic_debug/control
1201 // enable all the messages in the NFS server module
1202 nullarbor:~ # echo -n 'module nfsd +p' >
1203 <debugfs>/dynamic_debug/control
1205 // enable all 12 messages in the function svc_process()
1206 nullarbor:~ # echo -n 'func svc_process +p' >
1207 <debugfs>/dynamic_debug/control
1209 // disable all 12 messages in the function svc_process()
1210 nullarbor:~ # echo -n 'func svc_process -p' >
1211 <debugfs>/dynamic_debug/control
1213 See Documentation/dynamic-debug-howto.txt for additional information.
1215 config DMA_API_DEBUG
1216 bool "Enable debugging of DMA-API usage"
1217 depends on HAVE_DMA_API_DEBUG
1218 help
1219 Enable this option to debug the use of the DMA API by device drivers.
1220 With this option you will be able to detect common bugs in device
1221 drivers like double-freeing of DMA mappings or freeing mappings that
1222 were never allocated.
1223 This option causes a performance degredation. Use only if you want
1224 to debug device drivers. If unsure, say N.
1226 config ATOMIC64_SELFTEST
1227 bool "Perform an atomic64_t self-test at boot"
1228 help
1229 Enable this option to test the atomic64_t functions at boot.
1231 If unsure, say N.
1233 config ASYNC_RAID6_TEST
1234 tristate "Self test for hardware accelerated raid6 recovery"
1235 depends on ASYNC_RAID6_RECOV
1236 select ASYNC_MEMCPY
1237 ---help---
1238 This is a one-shot self test that permutes through the
1239 recovery of all the possible two disk failure scenarios for a
1240 N-disk array. Recovery is performed with the asynchronous
1241 raid6 recovery routines, and will optionally use an offload
1242 engine if one is available.
1244 If unsure, say N.
1246 source "samples/Kconfig"
1248 source "lib/Kconfig.kgdb"
1250 source "lib/Kconfig.kmemcheck"
1252 config TEST_KSTRTOX
1253 tristate "Test kstrto*() family of functions at runtime"