| blob | 28b42b9274d0b5fe47522d9df8158498be12319a |
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 ENABLE_WARN_DEPRECATED
13 bool "Enable __deprecated logic"
14 default y
15 help
16 Enable the __deprecated logic in the kernel build.
17 Disable this to suppress the "warning: 'foo' is deprecated
18 (declared at kernel/power/somefile.c:1234)" messages.
20 config ENABLE_MUST_CHECK
21 bool "Enable __must_check logic"
22 default y
23 help
24 Enable the __must_check logic in the kernel build. Disable this to
25 suppress the "warning: ignoring return value of 'foo', declared with
26 attribute warn_unused_result" messages.
28 config FRAME_WARN
29 int "Warn for stack frames larger than (needs gcc 4.4)"
30 range 0 8192
31 default 1024 if !64BIT
32 default 2048 if 64BIT
33 help
34 Tell gcc to warn at build time for stack frames larger than this.
35 Setting this too low will cause a lot of warnings.
36 Setting it to 0 disables the warning.
37 Requires gcc 4.4
39 config MAGIC_SYSRQ
40 bool "Magic SysRq key"
41 depends on !UML
42 help
43 If you say Y here, you will have some control over the system even
44 if the system crashes for example during kernel debugging (e.g., you
45 will be able to flush the buffer cache to disk, reboot the system
46 immediately or dump some status information). This is accomplished
47 by pressing various keys while holding SysRq (Alt+PrintScreen). It
48 also works on a serial console (on PC hardware at least), if you
49 send a BREAK and then within 5 seconds a command keypress. The
50 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
51 unless you really know what this hack does.
53 config STRIP_ASM_SYMS
54 bool "Strip assembler-generated symbols during link"
55 default n
56 help
57 Strip internal assembler-generated symbols during a link (symbols
58 that look like '.Lxxx') so they don't pollute the output of
59 get_wchan() and suchlike.
61 config UNUSED_SYMBOLS
62 bool "Enable unused/obsolete exported symbols"
63 default y if X86
64 help
65 Unused but exported symbols make the kernel needlessly bigger. For
66 that reason most of these unused exports will soon be removed. This
67 option is provided temporarily to provide a transition period in case
68 some external kernel module needs one of these symbols anyway. If you
69 encounter such a case in your module, consider if you are actually
70 using the right API. (rationale: since nobody in the kernel is using
71 this in a module, there is a pretty good chance it's actually the
72 wrong interface to use). If you really need the symbol, please send a
73 mail to the linux kernel mailing list mentioning the symbol and why
74 you really need it, and what the merge plan to the mainline kernel for
75 your module is.
77 config DEBUG_FS
78 bool "Debug Filesystem"
79 help
80 debugfs is a virtual file system that kernel developers use to put
81 debugging files into. Enable this option to be able to read and
82 write to these files.
84 For detailed documentation on the debugfs API, see
85 Documentation/DocBook/filesystems.
87 If unsure, say N.
89 config HEADERS_CHECK
90 bool "Run 'make headers_check' when building vmlinux"
91 depends on !UML
92 help
93 This option will extract the user-visible kernel headers whenever
94 building the kernel, and will run basic sanity checks on them to
95 ensure that exported files do not attempt to include files which
96 were not exported, etc.
98 If you're making modifications to header files which are
99 relevant for userspace, say 'Y', and check the headers
100 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
101 your build tree), to make sure they're suitable.
103 config DEBUG_SECTION_MISMATCH
104 bool "Enable full Section mismatch analysis"
105 depends on UNDEFINED || (BLACKFIN)
106 default y
107 # This option is on purpose disabled for now.
108 # It will be enabled when we are down to a reasonable number
109 # of section mismatch warnings (< 10 for an allyesconfig build)
110 help
111 The section mismatch analysis checks if there are illegal
112 references from one section to another section.
113 Linux will during link or during runtime drop some sections
114 and any use of code/data previously in these sections will
115 most likely result in an oops.
116 In the code functions and variables are annotated with
117 __init, __devinit etc. (see full list in include/linux/init.h)
118 which results in the code/data being placed in specific sections.
119 The section mismatch analysis is always done after a full
120 kernel build but enabling this option will in addition
121 do the following:
122 - Add the option -fno-inline-functions-called-once to gcc
123 When inlining a function annotated __init in a non-init
124 function we would lose the section information and thus
125 the analysis would not catch the illegal reference.
126 This option tells gcc to inline less but will also
127 result in a larger kernel.
128 - Run the section mismatch analysis for each module/built-in.o
129 When we run the section mismatch analysis on vmlinux.o we
130 lose valueble information about where the mismatch was
131 introduced.
132 Running the analysis for each module/built-in.o file
133 will tell where the mismatch happens much closer to the
134 source. The drawback is that we will report the same
135 mismatch at least twice.
136 - Enable verbose reporting from modpost to help solving
137 the section mismatches reported.
139 config DEBUG_KERNEL
140 bool "Kernel debugging"
141 help
142 Say Y here if you are developing drivers or trying to debug and
143 identify kernel problems.
145 config DEBUG_SHIRQ
146 bool "Debug shared IRQ handlers"
147 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
148 help
149 Enable this to generate a spurious interrupt as soon as a shared
150 interrupt handler is registered, and just before one is deregistered.
151 Drivers ought to be able to handle interrupts coming in at those
152 points; some don't and need to be caught.
154 config LOCKUP_DETECTOR
155 bool "Detect Hard and Soft Lockups"
156 depends on DEBUG_KERNEL && !S390
157 help
158 Say Y here to enable the kernel to act as a watchdog to detect
159 hard and soft lockups.
161 Softlockups are bugs that cause the kernel to loop in kernel
162 mode for more than 60 seconds, without giving other tasks a
163 chance to run. The current stack trace is displayed upon
164 detection and the system will stay locked up.
166 Hardlockups are bugs that cause the CPU to loop in kernel mode
167 for more than 60 seconds, without letting other interrupts have a
168 chance to run. The current stack trace is displayed upon detection
169 and the system will stay locked up.
171 The overhead should be minimal. A periodic hrtimer runs to
172 generate interrupts and kick the watchdog task every 10-12 seconds.
173 An NMI is generated every 60 seconds or so to check for hardlockups.
175 config HARDLOCKUP_DETECTOR
176 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI
178 config BOOTPARAM_SOFTLOCKUP_PANIC
179 bool "Panic (Reboot) On Soft Lockups"
180 depends on LOCKUP_DETECTOR
181 help
182 Say Y here to enable the kernel to panic on "soft lockups",
183 which are bugs that cause the kernel to loop in kernel
184 mode for more than 60 seconds, without giving other tasks a
185 chance to run.
187 The panic can be used in combination with panic_timeout,
188 to cause the system to reboot automatically after a
189 lockup has been detected. This feature is useful for
190 high-availability systems that have uptime guarantees and
191 where a lockup must be resolved ASAP.
193 Say N if unsure.
195 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
196 int
197 depends on LOCKUP_DETECTOR
198 range 0 1
199 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
200 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
202 config DETECT_HUNG_TASK
203 bool "Detect Hung Tasks"
204 depends on DEBUG_KERNEL
205 default DETECT_SOFTLOCKUP
206 help
207 Say Y here to enable the kernel to detect "hung tasks",
208 which are bugs that cause the task to be stuck in
209 uninterruptible "D" state indefinitiley.
211 When a hung task is detected, the kernel will print the
212 current stack trace (which you should report), but the
213 task will stay in uninterruptible state. If lockdep is
214 enabled then all held locks will also be reported. This
215 feature has negligible overhead.
217 config BOOTPARAM_HUNG_TASK_PANIC
218 bool "Panic (Reboot) On Hung Tasks"
219 depends on DETECT_HUNG_TASK
220 help
221 Say Y here to enable the kernel to panic on "hung tasks",
222 which are bugs that cause the kernel to leave a task stuck
223 in uninterruptible "D" state.
225 The panic can be used in combination with panic_timeout,
226 to cause the system to reboot automatically after a
227 hung task has been detected. This feature is useful for
228 high-availability systems that have uptime guarantees and
229 where a hung tasks must be resolved ASAP.
231 Say N if unsure.
233 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
234 int
235 depends on DETECT_HUNG_TASK
236 range 0 1
237 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
238 default 1 if BOOTPARAM_HUNG_TASK_PANIC
240 config SCHED_DEBUG
241 bool "Collect scheduler debugging info"
242 depends on DEBUG_KERNEL && PROC_FS
243 default y
244 help
245 If you say Y here, the /proc/sched_debug file will be provided
246 that can help debug the scheduler. The runtime overhead of this
247 option is minimal.
249 config SCHEDSTATS
250 bool "Collect scheduler statistics"
251 depends on DEBUG_KERNEL && PROC_FS
252 help
253 If you say Y here, additional code will be inserted into the
254 scheduler and related routines to collect statistics about
255 scheduler behavior and provide them in /proc/schedstat. These
256 stats may be useful for both tuning and debugging the scheduler
257 If you aren't debugging the scheduler or trying to tune a specific
258 application, you can say N to avoid the very slight overhead
259 this adds.
261 config TIMER_STATS
262 bool "Collect kernel timers statistics"
263 depends on DEBUG_KERNEL && PROC_FS
264 help
265 If you say Y here, additional code will be inserted into the
266 timer routines to collect statistics about kernel timers being
267 reprogrammed. The statistics can be read from /proc/timer_stats.
268 The statistics collection is started by writing 1 to /proc/timer_stats,
269 writing 0 stops it. This feature is useful to collect information
270 about timer usage patterns in kernel and userspace. This feature
271 is lightweight if enabled in the kernel config but not activated
272 (it defaults to deactivated on bootup and will only be activated
273 if some application like powertop activates it explicitly).
275 config DEBUG_OBJECTS
276 bool "Debug object operations"
277 depends on DEBUG_KERNEL
278 help
279 If you say Y here, additional code will be inserted into the
280 kernel to track the life time of various objects and validate
281 the operations on those objects.
283 config DEBUG_OBJECTS_SELFTEST
284 bool "Debug objects selftest"
285 depends on DEBUG_OBJECTS
286 help
287 This enables the selftest of the object debug code.
289 config DEBUG_OBJECTS_FREE
290 bool "Debug objects in freed memory"
291 depends on DEBUG_OBJECTS
292 help
293 This enables checks whether a k/v free operation frees an area
294 which contains an object which has not been deactivated
295 properly. This can make kmalloc/kfree-intensive workloads
296 much slower.
298 config DEBUG_OBJECTS_TIMERS
299 bool "Debug timer objects"
300 depends on DEBUG_OBJECTS
301 help
302 If you say Y here, additional code will be inserted into the
303 timer routines to track the life time of timer objects and
304 validate the timer operations.
306 config DEBUG_OBJECTS_WORK
307 bool "Debug work objects"
308 depends on DEBUG_OBJECTS
309 help
310 If you say Y here, additional code will be inserted into the
311 work queue routines to track the life time of work objects and
312 validate the work operations.
314 config DEBUG_OBJECTS_RCU_HEAD
315 bool "Debug RCU callbacks objects"
316 depends on DEBUG_OBJECTS && PREEMPT
317 help
318 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
320 config DEBUG_OBJECTS_PERCPU_COUNTER
321 bool "Debug percpu counter objects"
322 depends on DEBUG_OBJECTS
323 help
324 If you say Y here, additional code will be inserted into the
325 percpu counter routines to track the life time of percpu counter
326 objects and validate the percpu counter operations.
328 config DEBUG_OBJECTS_ENABLE_DEFAULT
329 int "debug_objects bootup default value (0-1)"
330 range 0 1
331 default "1"
332 depends on DEBUG_OBJECTS
333 help
334 Debug objects boot parameter default value
336 config DEBUG_SLAB
337 bool "Debug slab memory allocations"
338 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
339 help
340 Say Y here to have the kernel do limited verification on memory
341 allocation as well as poisoning memory on free to catch use of freed
342 memory. This can make kmalloc/kfree-intensive workloads much slower.
344 config DEBUG_SLAB_LEAK
345 bool "Memory leak debugging"
346 depends on DEBUG_SLAB
348 config SLUB_DEBUG_ON
349 bool "SLUB debugging on by default"
350 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
351 default n
352 help
353 Boot with debugging on by default. SLUB boots by default with
354 the runtime debug capabilities switched off. Enabling this is
355 equivalent to specifying the "slub_debug" parameter on boot.
356 There is no support for more fine grained debug control like
357 possible with slub_debug=xxx. SLUB debugging may be switched
358 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
359 "slub_debug=-".
361 config SLUB_STATS
362 default n
363 bool "Enable SLUB performance statistics"
364 depends on SLUB && SYSFS
365 help
366 SLUB statistics are useful to debug SLUBs allocation behavior in
367 order find ways to optimize the allocator. This should never be
368 enabled for production use since keeping statistics slows down
369 the allocator by a few percentage points. The slabinfo command
370 supports the determination of the most active slabs to figure
371 out which slabs are relevant to a particular load.
372 Try running: slabinfo -DA
374 config DEBUG_KMEMLEAK
375 bool "Kernel memory leak detector"
376 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
377 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
379 select DEBUG_FS if SYSFS
380 select STACKTRACE if STACKTRACE_SUPPORT
381 select KALLSYMS
382 select CRC32
383 help
384 Say Y here if you want to enable the memory leak
385 detector. The memory allocation/freeing is traced in a way
386 similar to the Boehm's conservative garbage collector, the
387 difference being that the orphan objects are not freed but
388 only shown in /sys/kernel/debug/kmemleak. Enabling this
389 feature will introduce an overhead to memory
390 allocations. See Documentation/kmemleak.txt for more
391 details.
393 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
394 of finding leaks due to the slab objects poisoning.
396 In order to access the kmemleak file, debugfs needs to be
397 mounted (usually at /sys/kernel/debug).
399 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
400 int "Maximum kmemleak early log entries"
401 depends on DEBUG_KMEMLEAK
402 range 200 40000
403 default 400
404 help
405 Kmemleak must track all the memory allocations to avoid
406 reporting false positives. Since memory may be allocated or
407 freed before kmemleak is initialised, an early log buffer is
408 used to store these actions. If kmemleak reports "early log
409 buffer exceeded", please increase this value.
411 config DEBUG_KMEMLEAK_TEST
412 tristate "Simple test for the kernel memory leak detector"
413 depends on DEBUG_KMEMLEAK
414 help
415 Say Y or M here to build a test for the kernel memory leak
416 detector. This option enables a module that explicitly leaks
417 memory.
419 If unsure, say N.
421 config DEBUG_KMEMLEAK_DEFAULT_OFF
422 bool "Default kmemleak to off"
423 depends on DEBUG_KMEMLEAK
424 help
425 Say Y here to disable kmemleak by default. It can then be enabled
426 on the command line via kmemleak=on.
428 config DEBUG_PREEMPT
429 bool "Debug preemptible kernel"
430 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
431 default y
432 help
433 If you say Y here then the kernel will use a debug variant of the
434 commonly used smp_processor_id() function and will print warnings
435 if kernel code uses it in a preemption-unsafe way. Also, the kernel
436 will detect preemption count underflows.
438 config DEBUG_RT_MUTEXES
439 bool "RT Mutex debugging, deadlock detection"
440 depends on DEBUG_KERNEL && RT_MUTEXES
441 help
442 This allows rt mutex semantics violations and rt mutex related
443 deadlocks (lockups) to be detected and reported automatically.
445 config DEBUG_PI_LIST
446 bool
447 default y
448 depends on DEBUG_RT_MUTEXES
450 config RT_MUTEX_TESTER
451 bool "Built-in scriptable tester for rt-mutexes"
452 depends on DEBUG_KERNEL && RT_MUTEXES
453 help
454 This option enables a rt-mutex tester.
456 config DEBUG_SPINLOCK
457 bool "Spinlock and rw-lock debugging: basic checks"
458 depends on DEBUG_KERNEL
459 help
460 Say Y here and build SMP to catch missing spinlock initialization
461 and certain other kinds of spinlock errors commonly made. This is
462 best used in conjunction with the NMI watchdog so that spinlock
463 deadlocks are also debuggable.
465 config DEBUG_MUTEXES
466 bool "Mutex debugging: basic checks"
467 depends on DEBUG_KERNEL
468 help
469 This feature allows mutex semantics violations to be detected and
470 reported.
472 config BKL
473 bool "Big Kernel Lock" if (SMP || PREEMPT)
474 default y
475 help
476 This is the traditional lock that is used in old code instead
477 of proper locking. All drivers that use the BKL should depend
478 on this symbol.
479 Say Y here unless you are working on removing the BKL.
481 config DEBUG_LOCK_ALLOC
482 bool "Lock debugging: detect incorrect freeing of live locks"
483 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
484 select DEBUG_SPINLOCK
485 select DEBUG_MUTEXES
486 select LOCKDEP
487 help
488 This feature will check whether any held lock (spinlock, rwlock,
489 mutex or rwsem) is incorrectly freed by the kernel, via any of the
490 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
491 vfree(), etc.), whether a live lock is incorrectly reinitialized via
492 spin_lock_init()/mutex_init()/etc., or whether there is any lock
493 held during task exit.
495 config PROVE_LOCKING
496 bool "Lock debugging: prove locking correctness"
497 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
498 select LOCKDEP
499 select DEBUG_SPINLOCK
500 select DEBUG_MUTEXES
501 select DEBUG_LOCK_ALLOC
502 select TRACE_IRQFLAGS
503 default n
504 help
505 This feature enables the kernel to prove that all locking
506 that occurs in the kernel runtime is mathematically
507 correct: that under no circumstance could an arbitrary (and
508 not yet triggered) combination of observed locking
509 sequences (on an arbitrary number of CPUs, running an
510 arbitrary number of tasks and interrupt contexts) cause a
511 deadlock.
513 In short, this feature enables the kernel to report locking
514 related deadlocks before they actually occur.
516 The proof does not depend on how hard and complex a
517 deadlock scenario would be to trigger: how many
518 participant CPUs, tasks and irq-contexts would be needed
519 for it to trigger. The proof also does not depend on
520 timing: if a race and a resulting deadlock is possible
521 theoretically (no matter how unlikely the race scenario
522 is), it will be proven so and will immediately be
523 reported by the kernel (once the event is observed that
524 makes the deadlock theoretically possible).
526 If a deadlock is impossible (i.e. the locking rules, as
527 observed by the kernel, are mathematically correct), the
528 kernel reports nothing.
530 NOTE: this feature can also be enabled for rwlocks, mutexes
531 and rwsems - in which case all dependencies between these
532 different locking variants are observed and mapped too, and
533 the proof of observed correctness is also maintained for an
534 arbitrary combination of these separate locking variants.
536 For more details, see Documentation/lockdep-design.txt.
538 config PROVE_RCU
539 bool "RCU debugging: prove RCU correctness"
540 depends on PROVE_LOCKING
541 default n
542 help
543 This feature enables lockdep extensions that check for correct
544 use of RCU APIs. This is currently under development. Say Y
545 if you want to debug RCU usage or help work on the PROVE_RCU
546 feature.
548 Say N if you are unsure.
550 config PROVE_RCU_REPEATEDLY
551 bool "RCU debugging: don't disable PROVE_RCU on first splat"
552 depends on PROVE_RCU
553 default n
554 help
555 By itself, PROVE_RCU will disable checking upon issuing the
556 first warning (or "splat"). This feature prevents such
557 disabling, allowing multiple RCU-lockdep warnings to be printed
558 on a single reboot.
560 Say Y to allow multiple RCU-lockdep warnings per boot.
562 Say N if you are unsure.
564 config SPARSE_RCU_POINTER
565 bool "RCU debugging: sparse-based checks for pointer usage"
566 default n
567 help
568 This feature enables the __rcu sparse annotation for
569 RCU-protected pointers. This annotation will cause sparse
570 to flag any non-RCU used of annotated pointers. This can be
571 helpful when debugging RCU usage. Please note that this feature
572 is not intended to enforce code cleanliness; it is instead merely
573 a debugging aid.
575 Say Y to make sparse flag questionable use of RCU-protected pointers
577 Say N if you are unsure.
579 config LOCKDEP
580 bool
581 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
582 select STACKTRACE
583 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
584 select KALLSYMS
585 select KALLSYMS_ALL
587 config LOCK_STAT
588 bool "Lock usage statistics"
589 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
590 select LOCKDEP
591 select DEBUG_SPINLOCK
592 select DEBUG_MUTEXES
593 select DEBUG_LOCK_ALLOC
594 default n
595 help
596 This feature enables tracking lock contention points
598 For more details, see Documentation/lockstat.txt
600 This also enables lock events required by "perf lock",
601 subcommand of perf.
602 If you want to use "perf lock", you also need to turn on
603 CONFIG_EVENT_TRACING.
605 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
606 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
608 config DEBUG_LOCKDEP
609 bool "Lock dependency engine debugging"
610 depends on DEBUG_KERNEL && LOCKDEP
611 help
612 If you say Y here, the lock dependency engine will do
613 additional runtime checks to debug itself, at the price
614 of more runtime overhead.
616 config TRACE_IRQFLAGS
617 bool
618 help
619 Enables hooks to interrupt enabling and disabling for
620 either tracing or lock debugging.
622 config DEBUG_SPINLOCK_SLEEP
623 bool "Spinlock debugging: sleep-inside-spinlock checking"
624 depends on DEBUG_KERNEL
625 help
626 If you say Y here, various routines which may sleep will become very
627 noisy if they are called with a spinlock held.
629 config DEBUG_LOCKING_API_SELFTESTS
630 bool "Locking API boot-time self-tests"
631 depends on DEBUG_KERNEL
632 help
633 Say Y here if you want the kernel to run a short self-test during
634 bootup. The self-test checks whether common types of locking bugs
635 are detected by debugging mechanisms or not. (if you disable
636 lock debugging then those bugs wont be detected of course.)
637 The following locking APIs are covered: spinlocks, rwlocks,
638 mutexes and rwsems.
640 config STACKTRACE
641 bool
642 depends on STACKTRACE_SUPPORT
644 config DEBUG_KOBJECT
645 bool "kobject debugging"
646 depends on DEBUG_KERNEL
647 help
648 If you say Y here, some extra kobject debugging messages will be sent
649 to the syslog.
651 config DEBUG_HIGHMEM
652 bool "Highmem debugging"
653 depends on DEBUG_KERNEL && HIGHMEM
654 help
655 This options enables addition error checking for high memory systems.
656 Disable for production systems.
658 config DEBUG_BUGVERBOSE
659 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
660 depends on BUG
661 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
662 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
663 default y
664 help
665 Say Y here to make BUG() panics output the file name and line number
666 of the BUG call as well as the EIP and oops trace. This aids
667 debugging but costs about 70-100K of memory.
669 config DEBUG_INFO
670 bool "Compile the kernel with debug info"
671 depends on DEBUG_KERNEL
672 help
673 If you say Y here the resulting kernel image will include
674 debugging info resulting in a larger kernel image.
675 This adds debug symbols to the kernel and modules (gcc -g), and
676 is needed if you intend to use kernel crashdump or binary object
677 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
678 Say Y here only if you plan to debug the kernel.
680 If unsure, say N.
682 config DEBUG_INFO_REDUCED
683 bool "Reduce debugging information"
684 depends on DEBUG_INFO
685 help
686 If you say Y here gcc is instructed to generate less debugging
687 information for structure types. This means that tools that
688 need full debugging information (like kgdb or systemtap) won't
689 be happy. But if you merely need debugging information to
690 resolve line numbers there is no loss. Advantage is that
691 build directory object sizes shrink dramatically over a full
692 DEBUG_INFO build and compile times are reduced too.
693 Only works with newer gcc versions.
695 config DEBUG_VM
696 bool "Debug VM"
697 depends on DEBUG_KERNEL
698 help
699 Enable this to turn on extended checks in the virtual-memory system
700 that may impact performance.
702 If unsure, say N.
704 config DEBUG_VIRTUAL
705 bool "Debug VM translations"
706 depends on DEBUG_KERNEL && X86
707 help
708 Enable some costly sanity checks in virtual to page code. This can
709 catch mistakes with virt_to_page() and friends.
711 If unsure, say N.
713 config DEBUG_NOMMU_REGIONS
714 bool "Debug the global anon/private NOMMU mapping region tree"
715 depends on DEBUG_KERNEL && !MMU
716 help
717 This option causes the global tree of anonymous and private mapping
718 regions to be regularly checked for invalid topology.
720 config DEBUG_WRITECOUNT
721 bool "Debug filesystem writers count"
722 depends on DEBUG_KERNEL
723 help
724 Enable this to catch wrong use of the writers count in struct
725 vfsmount. This will increase the size of each file struct by
726 32 bits.
728 If unsure, say N.
730 config DEBUG_MEMORY_INIT
731 bool "Debug memory initialisation" if EMBEDDED
732 default !EMBEDDED
733 help
734 Enable this for additional checks during memory initialisation.
735 The sanity checks verify aspects of the VM such as the memory model
736 and other information provided by the architecture. Verbose
737 information will be printed at KERN_DEBUG loglevel depending
738 on the mminit_loglevel= command-line option.
740 If unsure, say Y
742 config DEBUG_LIST
743 bool "Debug linked list manipulation"
744 depends on DEBUG_KERNEL
745 help
746 Enable this to turn on extended checks in the linked-list
747 walking routines.
749 If unsure, say N.
751 config TEST_LIST_SORT
752 bool "Linked list sorting test"
753 depends on DEBUG_KERNEL
754 help
755 Enable this to turn on 'list_sort()' function test. This test is
756 executed only once during system boot, so affects only boot time.
758 If unsure, say N.
760 config DEBUG_SG
761 bool "Debug SG table operations"
762 depends on DEBUG_KERNEL
763 help
764 Enable this to turn on checks on scatter-gather tables. This can
765 help find problems with drivers that do not properly initialize
766 their sg tables.
768 If unsure, say N.
770 config DEBUG_NOTIFIERS
771 bool "Debug notifier call chains"
772 depends on DEBUG_KERNEL
773 help
774 Enable this to turn on sanity checking for notifier call chains.
775 This is most useful for kernel developers to make sure that
776 modules properly unregister themselves from notifier chains.
777 This is a relatively cheap check but if you care about maximum
778 performance, say N.
780 config DEBUG_CREDENTIALS
781 bool "Debug credential management"
782 depends on DEBUG_KERNEL
783 help
784 Enable this to turn on some debug checking for credential
785 management. The additional code keeps track of the number of
786 pointers from task_structs to any given cred struct, and checks to
787 see that this number never exceeds the usage count of the cred
788 struct.
790 Furthermore, if SELinux is enabled, this also checks that the
791 security pointer in the cred struct is never seen to be invalid.
793 If unsure, say N.
795 #
796 # Select this config option from the architecture Kconfig, if it
797 # it is preferred to always offer frame pointers as a config
798 # option on the architecture (regardless of KERNEL_DEBUG):
799 #
800 config ARCH_WANT_FRAME_POINTERS
801 bool
802 help
804 config FRAME_POINTER
805 bool "Compile the kernel with frame pointers"
806 depends on DEBUG_KERNEL && \
807 (CRIS || M68K || M68KNOMMU || FRV || UML || \
808 AVR32 || SUPERH || BLACKFIN || MN10300) || \
809 ARCH_WANT_FRAME_POINTERS
810 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
811 help
812 If you say Y here the resulting kernel image will be slightly
813 larger and slower, but it gives very useful debugging information
814 in case of kernel bugs. (precise oopses/stacktraces/warnings)
816 config BOOT_PRINTK_DELAY
817 bool "Delay each boot printk message by N milliseconds"
818 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
819 help
820 This build option allows you to read kernel boot messages
821 by inserting a short delay after each one. The delay is
822 specified in milliseconds on the kernel command line,
823 using "boot_delay=N".
825 It is likely that you would also need to use "lpj=M" to preset
826 the "loops per jiffie" value.
827 See a previous boot log for the "lpj" value to use for your
828 system, and then set "lpj=M" before setting "boot_delay=N".
829 NOTE: Using this option may adversely affect SMP systems.
830 I.e., processors other than the first one may not boot up.
831 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
832 what it believes to be lockup conditions.
834 config RCU_TORTURE_TEST
835 tristate "torture tests for RCU"
836 depends on DEBUG_KERNEL
837 default n
838 help
839 This option provides a kernel module that runs torture tests
840 on the RCU infrastructure. The kernel module may be built
841 after the fact on the running kernel to be tested, if desired.
843 Say Y here if you want RCU torture tests to be built into
844 the kernel.
845 Say M if you want the RCU torture tests to build as a module.
846 Say N if you are unsure.
848 config RCU_TORTURE_TEST_RUNNABLE
849 bool "torture tests for RCU runnable by default"
850 depends on RCU_TORTURE_TEST = y
851 default n
852 help
853 This option provides a way to build the RCU torture tests
854 directly into the kernel without them starting up at boot
855 time. You can use /proc/sys/kernel/rcutorture_runnable
856 to manually override this setting. This /proc file is
857 available only when the RCU torture tests have been built
858 into the kernel.
860 Say Y here if you want the RCU torture tests to start during
861 boot (you probably don't).
862 Say N here if you want the RCU torture tests to start only
863 after being manually enabled via /proc.
865 config RCU_CPU_STALL_DETECTOR
866 bool "Check for stalled CPUs delaying RCU grace periods"
867 depends on TREE_RCU || TREE_PREEMPT_RCU
868 default y
869 help
870 This option causes RCU to printk information on which
871 CPUs are delaying the current grace period, but only when
872 the grace period extends for excessive time periods.
874 Say N if you want to disable such checks.
876 Say Y if you are unsure.
878 config RCU_CPU_STALL_TIMEOUT
879 int "RCU CPU stall timeout in seconds"
880 depends on RCU_CPU_STALL_DETECTOR
881 range 3 300
882 default 60
883 help
884 If a given RCU grace period extends more than the specified
885 number of seconds, a CPU stall warning is printed. If the
886 RCU grace period persists, additional CPU stall warnings are
887 printed at more widely spaced intervals.
889 config RCU_CPU_STALL_DETECTOR_RUNNABLE
890 bool "RCU CPU stall checking starts automatically at boot"
891 depends on RCU_CPU_STALL_DETECTOR
892 default y
893 help
894 If set, start checking for RCU CPU stalls immediately on
895 boot. Otherwise, RCU CPU stall checking must be manually
896 enabled.
898 Say Y if you are unsure.
900 Say N if you wish to suppress RCU CPU stall checking during boot.
902 config RCU_CPU_STALL_VERBOSE
903 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
904 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
905 default y
906 help
907 This option causes RCU to printk detailed per-task information
908 for any tasks that are stalling the current RCU grace period.
910 Say N if you are unsure.
912 Say Y if you want to enable such checks.
914 config KPROBES_SANITY_TEST
915 bool "Kprobes sanity tests"
916 depends on DEBUG_KERNEL
917 depends on KPROBES
918 default n
919 help
920 This option provides for testing basic kprobes functionality on
921 boot. A sample kprobe, jprobe and kretprobe are inserted and
922 verified for functionality.
924 Say N if you are unsure.
926 config BACKTRACE_SELF_TEST
927 tristate "Self test for the backtrace code"
928 depends on DEBUG_KERNEL
929 default n
930 help
931 This option provides a kernel module that can be used to test
932 the kernel stack backtrace code. This option is not useful
933 for distributions or general kernels, but only for kernel
934 developers working on architecture code.
936 Note that if you want to also test saved backtraces, you will
937 have to enable STACKTRACE as well.
939 Say N if you are unsure.
941 config DEBUG_BLOCK_EXT_DEVT
942 bool "Force extended block device numbers and spread them"
943 depends on DEBUG_KERNEL
944 depends on BLOCK
945 default n
946 help
947 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
948 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
949 YOU ARE DOING. Distros, please enable this and fix whatever
950 is broken.
952 Conventionally, block device numbers are allocated from
953 predetermined contiguous area. However, extended block area
954 may introduce non-contiguous block device numbers. This
955 option forces most block device numbers to be allocated from
956 the extended space and spreads them to discover kernel or
957 userland code paths which assume predetermined contiguous
958 device number allocation.
960 Note that turning on this debug option shuffles all the
961 device numbers for all IDE and SCSI devices including libata
962 ones, so root partition specified using device number
963 directly (via rdev or root=MAJ:MIN) won't work anymore.
964 Textual device names (root=/dev/sdXn) will continue to work.
966 Say N if you are unsure.
968 config DEBUG_FORCE_WEAK_PER_CPU
969 bool "Force weak per-cpu definitions"
970 depends on DEBUG_KERNEL
971 help
972 s390 and alpha require percpu variables in modules to be
973 defined weak to work around addressing range issue which
974 puts the following two restrictions on percpu variable
975 definitions.
977 1. percpu symbols must be unique whether static or not
978 2. percpu variables can't be defined inside a function
980 To ensure that generic code follows the above rules, this
981 option forces all percpu variables to be defined as weak.
983 config LKDTM
984 tristate "Linux Kernel Dump Test Tool Module"
985 depends on DEBUG_FS
986 depends on BLOCK
987 default n
988 help
989 This module enables testing of the different dumping mechanisms by
990 inducing system failures at predefined crash points.
991 If you don't need it: say N
992 Choose M here to compile this code as a module. The module will be
993 called lkdtm.
995 Documentation on how to use the module can be found in
996 Documentation/fault-injection/provoke-crashes.txt
998 config CPU_NOTIFIER_ERROR_INJECT
999 tristate "CPU notifier error injection module"
1000 depends on HOTPLUG_CPU && DEBUG_KERNEL
1001 help
1002 This option provides a kernel module that can be used to test
1003 the error handling of the cpu notifiers
1005 To compile this code as a module, choose M here: the module will
1006 be called cpu-notifier-error-inject.
1008 If unsure, say N.
1010 config FAULT_INJECTION
1011 bool "Fault-injection framework"
1012 depends on DEBUG_KERNEL
1013 help
1014 Provide fault-injection framework.
1015 For more details, see Documentation/fault-injection/.
1017 config FAILSLAB
1018 bool "Fault-injection capability for kmalloc"
1019 depends on FAULT_INJECTION
1020 depends on SLAB || SLUB
1021 help
1022 Provide fault-injection capability for kmalloc.
1024 config FAIL_PAGE_ALLOC
1025 bool "Fault-injection capabilitiy for alloc_pages()"
1026 depends on FAULT_INJECTION
1027 help
1028 Provide fault-injection capability for alloc_pages().
1030 config FAIL_MAKE_REQUEST
1031 bool "Fault-injection capability for disk IO"
1032 depends on FAULT_INJECTION && BLOCK
1033 help
1034 Provide fault-injection capability for disk IO.
1036 config FAIL_IO_TIMEOUT
1037 bool "Fault-injection capability for faking disk interrupts"
1038 depends on FAULT_INJECTION && BLOCK
1039 help
1040 Provide fault-injection capability on end IO handling. This
1041 will make the block layer "forget" an interrupt as configured,
1042 thus exercising the error handling.
1044 Only works with drivers that use the generic timeout handling,
1045 for others it wont do anything.
1047 config FAULT_INJECTION_DEBUG_FS
1048 bool "Debugfs entries for fault-injection capabilities"
1049 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1050 help
1051 Enable configuration of fault-injection capabilities via debugfs.
1053 config FAULT_INJECTION_STACKTRACE_FILTER
1054 bool "stacktrace filter for fault-injection capabilities"
1055 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1056 depends on !X86_64
1057 select STACKTRACE
1058 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
1059 help
1060 Provide stacktrace filter for fault-injection capabilities
1062 config LATENCYTOP
1063 bool "Latency measuring infrastructure"
1064 depends on HAVE_LATENCYTOP_SUPPORT
1065 depends on DEBUG_KERNEL
1066 depends on STACKTRACE_SUPPORT
1067 depends on PROC_FS
1068 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
1069 select KALLSYMS
1070 select KALLSYMS_ALL
1071 select STACKTRACE
1072 select SCHEDSTATS
1073 select SCHED_DEBUG
1074 help
1075 Enable this option if you want to use the LatencyTOP tool
1076 to find out which userspace is blocking on what kernel operations.
1078 config SYSCTL_SYSCALL_CHECK
1079 bool "Sysctl checks"
1080 depends on SYSCTL
1081 ---help---
1082 sys_sysctl uses binary paths that have been found challenging
1083 to properly maintain and use. This enables checks that help
1084 you to keep things correct.
1086 source mm/Kconfig.debug
1087 source kernel/trace/Kconfig
1089 config PROVIDE_OHCI1394_DMA_INIT
1090 bool "Remote debugging over FireWire early on boot"
1091 depends on PCI && X86
1092 help
1093 If you want to debug problems which hang or crash the kernel early
1094 on boot and the crashing machine has a FireWire port, you can use
1095 this feature to remotely access the memory of the crashed machine
1096 over FireWire. This employs remote DMA as part of the OHCI1394
1097 specification which is now the standard for FireWire controllers.
1099 With remote DMA, you can monitor the printk buffer remotely using
1100 firescope and access all memory below 4GB using fireproxy from gdb.
1101 Even controlling a kernel debugger is possible using remote DMA.
1103 Usage:
1105 If ohci1394_dma=early is used as boot parameter, it will initialize
1106 all OHCI1394 controllers which are found in the PCI config space.
1108 As all changes to the FireWire bus such as enabling and disabling
1109 devices cause a bus reset and thereby disable remote DMA for all
1110 devices, be sure to have the cable plugged and FireWire enabled on
1111 the debugging host before booting the debug target for debugging.
1113 This code (~1k) is freed after boot. By then, the firewire stack
1114 in charge of the OHCI-1394 controllers should be used instead.
1116 See Documentation/debugging-via-ohci1394.txt for more information.
1118 config FIREWIRE_OHCI_REMOTE_DMA
1119 bool "Remote debugging over FireWire with firewire-ohci"
1120 depends on FIREWIRE_OHCI
1121 help
1122 This option lets you use the FireWire bus for remote debugging
1123 with help of the firewire-ohci driver. It enables unfiltered
1124 remote DMA in firewire-ohci.
1125 See Documentation/debugging-via-ohci1394.txt for more information.
1127 If unsure, say N.
1129 config BUILD_DOCSRC
1130 bool "Build targets in Documentation/ tree"
1131 depends on HEADERS_CHECK
1132 help
1133 This option attempts to build objects from the source files in the
1134 kernel Documentation/ tree.
1136 Say N if you are unsure.
1138 config DYNAMIC_DEBUG
1139 bool "Enable dynamic printk() support"
1140 default n
1141 depends on PRINTK
1142 depends on DEBUG_FS
1143 help
1145 Compiles debug level messages into the kernel, which would not
1146 otherwise be available at runtime. These messages can then be
1147 enabled/disabled based on various levels of scope - per source file,
1148 function, module, format string, and line number. This mechanism
1149 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1150 this compile option is a larger kernel text size of about 2%.
1152 Usage:
1154 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1155 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1156 filesystem must first be mounted before making use of this feature.
1157 We refer the control file as: <debugfs>/dynamic_debug/control. This
1158 file contains a list of the debug statements that can be enabled. The
1159 format for each line of the file is:
1161 filename:lineno [module]function flags format
1163 filename : source file of the debug statement
1164 lineno : line number of the debug statement
1165 module : module that contains the debug statement
1166 function : function that contains the debug statement
1167 flags : 'p' means the line is turned 'on' for printing
1168 format : the format used for the debug statement
1170 From a live system:
1172 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1173 # filename:lineno [module]function flags format
1174 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1175 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1176 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1178 Example usage:
1180 // enable the message at line 1603 of file svcsock.c
1181 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1182 <debugfs>/dynamic_debug/control
1184 // enable all the messages in file svcsock.c
1185 nullarbor:~ # echo -n 'file svcsock.c +p' >
1186 <debugfs>/dynamic_debug/control
1188 // enable all the messages in the NFS server module
1189 nullarbor:~ # echo -n 'module nfsd +p' >
1190 <debugfs>/dynamic_debug/control
1192 // enable all 12 messages in the function svc_process()
1193 nullarbor:~ # echo -n 'func svc_process +p' >
1194 <debugfs>/dynamic_debug/control
1196 // disable all 12 messages in the function svc_process()
1197 nullarbor:~ # echo -n 'func svc_process -p' >
1198 <debugfs>/dynamic_debug/control
1200 See Documentation/dynamic-debug-howto.txt for additional information.
1202 config DMA_API_DEBUG
1203 bool "Enable debugging of DMA-API usage"
1204 depends on HAVE_DMA_API_DEBUG
1205 help
1206 Enable this option to debug the use of the DMA API by device drivers.
1207 With this option you will be able to detect common bugs in device
1208 drivers like double-freeing of DMA mappings or freeing mappings that
1209 were never allocated.
1210 This option causes a performance degredation. Use only if you want
1211 to debug device drivers. If unsure, say N.
1213 config ATOMIC64_SELFTEST
1214 bool "Perform an atomic64_t self-test at boot"
1215 help
1216 Enable this option to test the atomic64_t functions at boot.
1218 If unsure, say N.
1220 config ASYNC_RAID6_TEST
1221 tristate "Self test for hardware accelerated raid6 recovery"
1222 depends on ASYNC_RAID6_RECOV
1223 select ASYNC_MEMCPY
1224 ---help---
1225 This is a one-shot self test that permutes through the
1226 recovery of all the possible two disk failure scenarios for a
1227 N-disk array. Recovery is performed with the asynchronous
1228 raid6 recovery routines, and will optionally use an offload
1229 engine if one is available.
1231 If unsure, say N.
1233 source "samples/Kconfig"
1235 source "lib/Kconfig.kgdb"
1237 source "lib/Kconfig.kmemcheck"