| blob | 2b97418c67e2f68f1ddf355cae1091ae1b3eafed |
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 && \
177 !ARCH_HAS_NMI_WATCHDOG
179 config BOOTPARAM_SOFTLOCKUP_PANIC
180 bool "Panic (Reboot) On Soft Lockups"
181 depends on LOCKUP_DETECTOR
182 help
183 Say Y here to enable the kernel to panic on "soft lockups",
184 which are bugs that cause the kernel to loop in kernel
185 mode for more than 60 seconds, without giving other tasks a
186 chance to run.
188 The panic can be used in combination with panic_timeout,
189 to cause the system to reboot automatically after a
190 lockup has been detected. This feature is useful for
191 high-availability systems that have uptime guarantees and
192 where a lockup must be resolved ASAP.
194 Say N if unsure.
196 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
197 int
198 depends on LOCKUP_DETECTOR
199 range 0 1
200 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
201 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
203 config DETECT_HUNG_TASK
204 bool "Detect Hung Tasks"
205 depends on DEBUG_KERNEL
206 default DETECT_SOFTLOCKUP
207 help
208 Say Y here to enable the kernel to detect "hung tasks",
209 which are bugs that cause the task to be stuck in
210 uninterruptible "D" state indefinitiley.
212 When a hung task is detected, the kernel will print the
213 current stack trace (which you should report), but the
214 task will stay in uninterruptible state. If lockdep is
215 enabled then all held locks will also be reported. This
216 feature has negligible overhead.
218 config BOOTPARAM_HUNG_TASK_PANIC
219 bool "Panic (Reboot) On Hung Tasks"
220 depends on DETECT_HUNG_TASK
221 help
222 Say Y here to enable the kernel to panic on "hung tasks",
223 which are bugs that cause the kernel to leave a task stuck
224 in uninterruptible "D" state.
226 The panic can be used in combination with panic_timeout,
227 to cause the system to reboot automatically after a
228 hung task has been detected. This feature is useful for
229 high-availability systems that have uptime guarantees and
230 where a hung tasks must be resolved ASAP.
232 Say N if unsure.
234 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
235 int
236 depends on DETECT_HUNG_TASK
237 range 0 1
238 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
239 default 1 if BOOTPARAM_HUNG_TASK_PANIC
241 config SCHED_DEBUG
242 bool "Collect scheduler debugging info"
243 depends on DEBUG_KERNEL && PROC_FS
244 default y
245 help
246 If you say Y here, the /proc/sched_debug file will be provided
247 that can help debug the scheduler. The runtime overhead of this
248 option is minimal.
250 config SCHEDSTATS
251 bool "Collect scheduler statistics"
252 depends on DEBUG_KERNEL && PROC_FS
253 help
254 If you say Y here, additional code will be inserted into the
255 scheduler and related routines to collect statistics about
256 scheduler behavior and provide them in /proc/schedstat. These
257 stats may be useful for both tuning and debugging the scheduler
258 If you aren't debugging the scheduler or trying to tune a specific
259 application, you can say N to avoid the very slight overhead
260 this adds.
262 config TIMER_STATS
263 bool "Collect kernel timers statistics"
264 depends on DEBUG_KERNEL && PROC_FS
265 help
266 If you say Y here, additional code will be inserted into the
267 timer routines to collect statistics about kernel timers being
268 reprogrammed. The statistics can be read from /proc/timer_stats.
269 The statistics collection is started by writing 1 to /proc/timer_stats,
270 writing 0 stops it. This feature is useful to collect information
271 about timer usage patterns in kernel and userspace. This feature
272 is lightweight if enabled in the kernel config but not activated
273 (it defaults to deactivated on bootup and will only be activated
274 if some application like powertop activates it explicitly).
276 config DEBUG_OBJECTS
277 bool "Debug object operations"
278 depends on DEBUG_KERNEL
279 help
280 If you say Y here, additional code will be inserted into the
281 kernel to track the life time of various objects and validate
282 the operations on those objects.
284 config DEBUG_OBJECTS_SELFTEST
285 bool "Debug objects selftest"
286 depends on DEBUG_OBJECTS
287 help
288 This enables the selftest of the object debug code.
290 config DEBUG_OBJECTS_FREE
291 bool "Debug objects in freed memory"
292 depends on DEBUG_OBJECTS
293 help
294 This enables checks whether a k/v free operation frees an area
295 which contains an object which has not been deactivated
296 properly. This can make kmalloc/kfree-intensive workloads
297 much slower.
299 config DEBUG_OBJECTS_TIMERS
300 bool "Debug timer objects"
301 depends on DEBUG_OBJECTS
302 help
303 If you say Y here, additional code will be inserted into the
304 timer routines to track the life time of timer objects and
305 validate the timer operations.
307 config DEBUG_OBJECTS_WORK
308 bool "Debug work objects"
309 depends on DEBUG_OBJECTS
310 help
311 If you say Y here, additional code will be inserted into the
312 work queue routines to track the life time of work objects and
313 validate the work operations.
315 config DEBUG_OBJECTS_RCU_HEAD
316 bool "Debug RCU callbacks objects"
317 depends on DEBUG_OBJECTS && PREEMPT
318 help
319 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
321 config DEBUG_OBJECTS_PERCPU_COUNTER
322 bool "Debug percpu counter objects"
323 depends on DEBUG_OBJECTS
324 help
325 If you say Y here, additional code will be inserted into the
326 percpu counter routines to track the life time of percpu counter
327 objects and validate the percpu counter operations.
329 config DEBUG_OBJECTS_ENABLE_DEFAULT
330 int "debug_objects bootup default value (0-1)"
331 range 0 1
332 default "1"
333 depends on DEBUG_OBJECTS
334 help
335 Debug objects boot parameter default value
337 config DEBUG_SLAB
338 bool "Debug slab memory allocations"
339 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
340 help
341 Say Y here to have the kernel do limited verification on memory
342 allocation as well as poisoning memory on free to catch use of freed
343 memory. This can make kmalloc/kfree-intensive workloads much slower.
345 config DEBUG_SLAB_LEAK
346 bool "Memory leak debugging"
347 depends on DEBUG_SLAB
349 config SLUB_DEBUG_ON
350 bool "SLUB debugging on by default"
351 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
352 default n
353 help
354 Boot with debugging on by default. SLUB boots by default with
355 the runtime debug capabilities switched off. Enabling this is
356 equivalent to specifying the "slub_debug" parameter on boot.
357 There is no support for more fine grained debug control like
358 possible with slub_debug=xxx. SLUB debugging may be switched
359 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
360 "slub_debug=-".
362 config SLUB_STATS
363 default n
364 bool "Enable SLUB performance statistics"
365 depends on SLUB && SYSFS
366 help
367 SLUB statistics are useful to debug SLUBs allocation behavior in
368 order find ways to optimize the allocator. This should never be
369 enabled for production use since keeping statistics slows down
370 the allocator by a few percentage points. The slabinfo command
371 supports the determination of the most active slabs to figure
372 out which slabs are relevant to a particular load.
373 Try running: slabinfo -DA
375 config DEBUG_KMEMLEAK
376 bool "Kernel memory leak detector"
377 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
378 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
380 select DEBUG_FS if SYSFS
381 select STACKTRACE if STACKTRACE_SUPPORT
382 select KALLSYMS
383 select CRC32
384 help
385 Say Y here if you want to enable the memory leak
386 detector. The memory allocation/freeing is traced in a way
387 similar to the Boehm's conservative garbage collector, the
388 difference being that the orphan objects are not freed but
389 only shown in /sys/kernel/debug/kmemleak. Enabling this
390 feature will introduce an overhead to memory
391 allocations. See Documentation/kmemleak.txt for more
392 details.
394 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
395 of finding leaks due to the slab objects poisoning.
397 In order to access the kmemleak file, debugfs needs to be
398 mounted (usually at /sys/kernel/debug).
400 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
401 int "Maximum kmemleak early log entries"
402 depends on DEBUG_KMEMLEAK
403 range 200 40000
404 default 400
405 help
406 Kmemleak must track all the memory allocations to avoid
407 reporting false positives. Since memory may be allocated or
408 freed before kmemleak is initialised, an early log buffer is
409 used to store these actions. If kmemleak reports "early log
410 buffer exceeded", please increase this value.
412 config DEBUG_KMEMLEAK_TEST
413 tristate "Simple test for the kernel memory leak detector"
414 depends on DEBUG_KMEMLEAK
415 help
416 Say Y or M here to build a test for the kernel memory leak
417 detector. This option enables a module that explicitly leaks
418 memory.
420 If unsure, say N.
422 config DEBUG_KMEMLEAK_DEFAULT_OFF
423 bool "Default kmemleak to off"
424 depends on DEBUG_KMEMLEAK
425 help
426 Say Y here to disable kmemleak by default. It can then be enabled
427 on the command line via kmemleak=on.
429 config DEBUG_PREEMPT
430 bool "Debug preemptible kernel"
431 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
432 default y
433 help
434 If you say Y here then the kernel will use a debug variant of the
435 commonly used smp_processor_id() function and will print warnings
436 if kernel code uses it in a preemption-unsafe way. Also, the kernel
437 will detect preemption count underflows.
439 config DEBUG_RT_MUTEXES
440 bool "RT Mutex debugging, deadlock detection"
441 depends on DEBUG_KERNEL && RT_MUTEXES
442 help
443 This allows rt mutex semantics violations and rt mutex related
444 deadlocks (lockups) to be detected and reported automatically.
446 config DEBUG_PI_LIST
447 bool
448 default y
449 depends on DEBUG_RT_MUTEXES
451 config RT_MUTEX_TESTER
452 bool "Built-in scriptable tester for rt-mutexes"
453 depends on DEBUG_KERNEL && RT_MUTEXES
454 help
455 This option enables a rt-mutex tester.
457 config DEBUG_SPINLOCK
458 bool "Spinlock and rw-lock debugging: basic checks"
459 depends on DEBUG_KERNEL
460 help
461 Say Y here and build SMP to catch missing spinlock initialization
462 and certain other kinds of spinlock errors commonly made. This is
463 best used in conjunction with the NMI watchdog so that spinlock
464 deadlocks are also debuggable.
466 config DEBUG_MUTEXES
467 bool "Mutex debugging: basic checks"
468 depends on DEBUG_KERNEL
469 help
470 This feature allows mutex semantics violations to be detected and
471 reported.
473 config BKL
474 bool "Big Kernel Lock" if (SMP || PREEMPT)
475 default y
476 help
477 This is the traditional lock that is used in old code instead
478 of proper locking. All drivers that use the BKL should depend
479 on this symbol.
480 Say Y here unless you are working on removing the BKL.
482 config DEBUG_LOCK_ALLOC
483 bool "Lock debugging: detect incorrect freeing of live locks"
484 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
485 select DEBUG_SPINLOCK
486 select DEBUG_MUTEXES
487 select LOCKDEP
488 help
489 This feature will check whether any held lock (spinlock, rwlock,
490 mutex or rwsem) is incorrectly freed by the kernel, via any of the
491 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
492 vfree(), etc.), whether a live lock is incorrectly reinitialized via
493 spin_lock_init()/mutex_init()/etc., or whether there is any lock
494 held during task exit.
496 config PROVE_LOCKING
497 bool "Lock debugging: prove locking correctness"
498 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
499 select LOCKDEP
500 select DEBUG_SPINLOCK
501 select DEBUG_MUTEXES
502 select DEBUG_LOCK_ALLOC
503 select TRACE_IRQFLAGS
504 default n
505 help
506 This feature enables the kernel to prove that all locking
507 that occurs in the kernel runtime is mathematically
508 correct: that under no circumstance could an arbitrary (and
509 not yet triggered) combination of observed locking
510 sequences (on an arbitrary number of CPUs, running an
511 arbitrary number of tasks and interrupt contexts) cause a
512 deadlock.
514 In short, this feature enables the kernel to report locking
515 related deadlocks before they actually occur.
517 The proof does not depend on how hard and complex a
518 deadlock scenario would be to trigger: how many
519 participant CPUs, tasks and irq-contexts would be needed
520 for it to trigger. The proof also does not depend on
521 timing: if a race and a resulting deadlock is possible
522 theoretically (no matter how unlikely the race scenario
523 is), it will be proven so and will immediately be
524 reported by the kernel (once the event is observed that
525 makes the deadlock theoretically possible).
527 If a deadlock is impossible (i.e. the locking rules, as
528 observed by the kernel, are mathematically correct), the
529 kernel reports nothing.
531 NOTE: this feature can also be enabled for rwlocks, mutexes
532 and rwsems - in which case all dependencies between these
533 different locking variants are observed and mapped too, and
534 the proof of observed correctness is also maintained for an
535 arbitrary combination of these separate locking variants.
537 For more details, see Documentation/lockdep-design.txt.
539 config PROVE_RCU
540 bool "RCU debugging: prove RCU correctness"
541 depends on PROVE_LOCKING
542 default n
543 help
544 This feature enables lockdep extensions that check for correct
545 use of RCU APIs. This is currently under development. Say Y
546 if you want to debug RCU usage or help work on the PROVE_RCU
547 feature.
549 Say N if you are unsure.
551 config PROVE_RCU_REPEATEDLY
552 bool "RCU debugging: don't disable PROVE_RCU on first splat"
553 depends on PROVE_RCU
554 default n
555 help
556 By itself, PROVE_RCU will disable checking upon issuing the
557 first warning (or "splat"). This feature prevents such
558 disabling, allowing multiple RCU-lockdep warnings to be printed
559 on a single reboot.
561 Say Y to allow multiple RCU-lockdep warnings per boot.
563 Say N if you are unsure.
565 config SPARSE_RCU_POINTER
566 bool "RCU debugging: sparse-based checks for pointer usage"
567 default n
568 help
569 This feature enables the __rcu sparse annotation for
570 RCU-protected pointers. This annotation will cause sparse
571 to flag any non-RCU used of annotated pointers. This can be
572 helpful when debugging RCU usage. Please note that this feature
573 is not intended to enforce code cleanliness; it is instead merely
574 a debugging aid.
576 Say Y to make sparse flag questionable use of RCU-protected pointers
578 Say N if you are unsure.
580 config LOCKDEP
581 bool
582 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
583 select STACKTRACE
584 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
585 select KALLSYMS
586 select KALLSYMS_ALL
588 config LOCK_STAT
589 bool "Lock usage statistics"
590 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
591 select LOCKDEP
592 select DEBUG_SPINLOCK
593 select DEBUG_MUTEXES
594 select DEBUG_LOCK_ALLOC
595 default n
596 help
597 This feature enables tracking lock contention points
599 For more details, see Documentation/lockstat.txt
601 This also enables lock events required by "perf lock",
602 subcommand of perf.
603 If you want to use "perf lock", you also need to turn on
604 CONFIG_EVENT_TRACING.
606 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
607 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
609 config DEBUG_LOCKDEP
610 bool "Lock dependency engine debugging"
611 depends on DEBUG_KERNEL && LOCKDEP
612 help
613 If you say Y here, the lock dependency engine will do
614 additional runtime checks to debug itself, at the price
615 of more runtime overhead.
617 config TRACE_IRQFLAGS
618 bool
619 help
620 Enables hooks to interrupt enabling and disabling for
621 either tracing or lock debugging.
623 config DEBUG_SPINLOCK_SLEEP
624 bool "Spinlock debugging: sleep-inside-spinlock checking"
625 depends on DEBUG_KERNEL
626 help
627 If you say Y here, various routines which may sleep will become very
628 noisy if they are called with a spinlock held.
630 config DEBUG_LOCKING_API_SELFTESTS
631 bool "Locking API boot-time self-tests"
632 depends on DEBUG_KERNEL
633 help
634 Say Y here if you want the kernel to run a short self-test during
635 bootup. The self-test checks whether common types of locking bugs
636 are detected by debugging mechanisms or not. (if you disable
637 lock debugging then those bugs wont be detected of course.)
638 The following locking APIs are covered: spinlocks, rwlocks,
639 mutexes and rwsems.
641 config STACKTRACE
642 bool
643 depends on STACKTRACE_SUPPORT
645 config DEBUG_KOBJECT
646 bool "kobject debugging"
647 depends on DEBUG_KERNEL
648 help
649 If you say Y here, some extra kobject debugging messages will be sent
650 to the syslog.
652 config DEBUG_HIGHMEM
653 bool "Highmem debugging"
654 depends on DEBUG_KERNEL && HIGHMEM
655 help
656 This options enables addition error checking for high memory systems.
657 Disable for production systems.
659 config DEBUG_BUGVERBOSE
660 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
661 depends on BUG
662 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
663 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
664 default y
665 help
666 Say Y here to make BUG() panics output the file name and line number
667 of the BUG call as well as the EIP and oops trace. This aids
668 debugging but costs about 70-100K of memory.
670 config DEBUG_INFO
671 bool "Compile the kernel with debug info"
672 depends on DEBUG_KERNEL
673 help
674 If you say Y here the resulting kernel image will include
675 debugging info resulting in a larger kernel image.
676 This adds debug symbols to the kernel and modules (gcc -g), and
677 is needed if you intend to use kernel crashdump or binary object
678 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
679 Say Y here only if you plan to debug the kernel.
681 If unsure, say N.
683 config DEBUG_INFO_REDUCED
684 bool "Reduce debugging information"
685 depends on DEBUG_INFO
686 help
687 If you say Y here gcc is instructed to generate less debugging
688 information for structure types. This means that tools that
689 need full debugging information (like kgdb or systemtap) won't
690 be happy. But if you merely need debugging information to
691 resolve line numbers there is no loss. Advantage is that
692 build directory object sizes shrink dramatically over a full
693 DEBUG_INFO build and compile times are reduced too.
694 Only works with newer gcc versions.
696 config DEBUG_VM
697 bool "Debug VM"
698 depends on DEBUG_KERNEL
699 help
700 Enable this to turn on extended checks in the virtual-memory system
701 that may impact performance.
703 If unsure, say N.
705 config DEBUG_VIRTUAL
706 bool "Debug VM translations"
707 depends on DEBUG_KERNEL && X86
708 help
709 Enable some costly sanity checks in virtual to page code. This can
710 catch mistakes with virt_to_page() and friends.
712 If unsure, say N.
714 config DEBUG_NOMMU_REGIONS
715 bool "Debug the global anon/private NOMMU mapping region tree"
716 depends on DEBUG_KERNEL && !MMU
717 help
718 This option causes the global tree of anonymous and private mapping
719 regions to be regularly checked for invalid topology.
721 config DEBUG_WRITECOUNT
722 bool "Debug filesystem writers count"
723 depends on DEBUG_KERNEL
724 help
725 Enable this to catch wrong use of the writers count in struct
726 vfsmount. This will increase the size of each file struct by
727 32 bits.
729 If unsure, say N.
731 config DEBUG_MEMORY_INIT
732 bool "Debug memory initialisation" if EXPERT
733 default !EXPERT
734 help
735 Enable this for additional checks during memory initialisation.
736 The sanity checks verify aspects of the VM such as the memory model
737 and other information provided by the architecture. Verbose
738 information will be printed at KERN_DEBUG loglevel depending
739 on the mminit_loglevel= command-line option.
741 If unsure, say Y
743 config DEBUG_LIST
744 bool "Debug linked list manipulation"
745 depends on DEBUG_KERNEL
746 help
747 Enable this to turn on extended checks in the linked-list
748 walking routines.
750 If unsure, say N.
752 config TEST_LIST_SORT
753 bool "Linked list sorting test"
754 depends on DEBUG_KERNEL
755 help
756 Enable this to turn on 'list_sort()' function test. This test is
757 executed only once during system boot, so affects only boot time.
759 If unsure, say N.
761 config DEBUG_SG
762 bool "Debug SG table operations"
763 depends on DEBUG_KERNEL
764 help
765 Enable this to turn on checks on scatter-gather tables. This can
766 help find problems with drivers that do not properly initialize
767 their sg tables.
769 If unsure, say N.
771 config DEBUG_NOTIFIERS
772 bool "Debug notifier call chains"
773 depends on DEBUG_KERNEL
774 help
775 Enable this to turn on sanity checking for notifier call chains.
776 This is most useful for kernel developers to make sure that
777 modules properly unregister themselves from notifier chains.
778 This is a relatively cheap check but if you care about maximum
779 performance, say N.
781 config DEBUG_CREDENTIALS
782 bool "Debug credential management"
783 depends on DEBUG_KERNEL
784 help
785 Enable this to turn on some debug checking for credential
786 management. The additional code keeps track of the number of
787 pointers from task_structs to any given cred struct, and checks to
788 see that this number never exceeds the usage count of the cred
789 struct.
791 Furthermore, if SELinux is enabled, this also checks that the
792 security pointer in the cred struct is never seen to be invalid.
794 If unsure, say N.
796 #
797 # Select this config option from the architecture Kconfig, if it
798 # it is preferred to always offer frame pointers as a config
799 # option on the architecture (regardless of KERNEL_DEBUG):
800 #
801 config ARCH_WANT_FRAME_POINTERS
802 bool
803 help
805 config FRAME_POINTER
806 bool "Compile the kernel with frame pointers"
807 depends on DEBUG_KERNEL && \
808 (CRIS || M68K || FRV || UML || \
809 AVR32 || SUPERH || BLACKFIN || MN10300) || \
810 ARCH_WANT_FRAME_POINTERS
811 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
812 help
813 If you say Y here the resulting kernel image will be slightly
814 larger and slower, but it gives very useful debugging information
815 in case of kernel bugs. (precise oopses/stacktraces/warnings)
817 config BOOT_PRINTK_DELAY
818 bool "Delay each boot printk message by N milliseconds"
819 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
820 help
821 This build option allows you to read kernel boot messages
822 by inserting a short delay after each one. The delay is
823 specified in milliseconds on the kernel command line,
824 using "boot_delay=N".
826 It is likely that you would also need to use "lpj=M" to preset
827 the "loops per jiffie" value.
828 See a previous boot log for the "lpj" value to use for your
829 system, and then set "lpj=M" before setting "boot_delay=N".
830 NOTE: Using this option may adversely affect SMP systems.
831 I.e., processors other than the first one may not boot up.
832 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
833 what it believes to be lockup conditions.
835 config RCU_TORTURE_TEST
836 tristate "torture tests for RCU"
837 depends on DEBUG_KERNEL
838 default n
839 help
840 This option provides a kernel module that runs torture tests
841 on the RCU infrastructure. The kernel module may be built
842 after the fact on the running kernel to be tested, if desired.
844 Say Y here if you want RCU torture tests to be built into
845 the kernel.
846 Say M if you want the RCU torture tests to build as a module.
847 Say N if you are unsure.
849 config RCU_TORTURE_TEST_RUNNABLE
850 bool "torture tests for RCU runnable by default"
851 depends on RCU_TORTURE_TEST = y
852 default n
853 help
854 This option provides a way to build the RCU torture tests
855 directly into the kernel without them starting up at boot
856 time. You can use /proc/sys/kernel/rcutorture_runnable
857 to manually override this setting. This /proc file is
858 available only when the RCU torture tests have been built
859 into the kernel.
861 Say Y here if you want the RCU torture tests to start during
862 boot (you probably don't).
863 Say N here if you want the RCU torture tests to start only
864 after being manually enabled via /proc.
866 config RCU_CPU_STALL_DETECTOR
867 bool "Check for stalled CPUs delaying RCU grace periods"
868 depends on TREE_RCU || TREE_PREEMPT_RCU
869 default y
870 help
871 This option causes RCU to printk information on which
872 CPUs are delaying the current grace period, but only when
873 the grace period extends for excessive time periods.
875 Say N if you want to disable such checks.
877 Say Y if you are unsure.
879 config RCU_CPU_STALL_TIMEOUT
880 int "RCU CPU stall timeout in seconds"
881 depends on RCU_CPU_STALL_DETECTOR
882 range 3 300
883 default 60
884 help
885 If a given RCU grace period extends more than the specified
886 number of seconds, a CPU stall warning is printed. If the
887 RCU grace period persists, additional CPU stall warnings are
888 printed at more widely spaced intervals.
890 config RCU_CPU_STALL_DETECTOR_RUNNABLE
891 bool "RCU CPU stall checking starts automatically at boot"
892 depends on RCU_CPU_STALL_DETECTOR
893 default y
894 help
895 If set, start checking for RCU CPU stalls immediately on
896 boot. Otherwise, RCU CPU stall checking must be manually
897 enabled.
899 Say Y if you are unsure.
901 Say N if you wish to suppress RCU CPU stall checking during boot.
903 config RCU_CPU_STALL_VERBOSE
904 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
905 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
906 default y
907 help
908 This option causes RCU to printk detailed per-task information
909 for any tasks that are stalling the current RCU grace period.
911 Say N if you are unsure.
913 Say Y if you want to enable such checks.
915 config KPROBES_SANITY_TEST
916 bool "Kprobes sanity tests"
917 depends on DEBUG_KERNEL
918 depends on KPROBES
919 default n
920 help
921 This option provides for testing basic kprobes functionality on
922 boot. A sample kprobe, jprobe and kretprobe are inserted and
923 verified for functionality.
925 Say N if you are unsure.
927 config BACKTRACE_SELF_TEST
928 tristate "Self test for the backtrace code"
929 depends on DEBUG_KERNEL
930 default n
931 help
932 This option provides a kernel module that can be used to test
933 the kernel stack backtrace code. This option is not useful
934 for distributions or general kernels, but only for kernel
935 developers working on architecture code.
937 Note that if you want to also test saved backtraces, you will
938 have to enable STACKTRACE as well.
940 Say N if you are unsure.
942 config DEBUG_BLOCK_EXT_DEVT
943 bool "Force extended block device numbers and spread them"
944 depends on DEBUG_KERNEL
945 depends on BLOCK
946 default n
947 help
948 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
949 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
950 YOU ARE DOING. Distros, please enable this and fix whatever
951 is broken.
953 Conventionally, block device numbers are allocated from
954 predetermined contiguous area. However, extended block area
955 may introduce non-contiguous block device numbers. This
956 option forces most block device numbers to be allocated from
957 the extended space and spreads them to discover kernel or
958 userland code paths which assume predetermined contiguous
959 device number allocation.
961 Note that turning on this debug option shuffles all the
962 device numbers for all IDE and SCSI devices including libata
963 ones, so root partition specified using device number
964 directly (via rdev or root=MAJ:MIN) won't work anymore.
965 Textual device names (root=/dev/sdXn) will continue to work.
967 Say N if you are unsure.
969 config DEBUG_FORCE_WEAK_PER_CPU
970 bool "Force weak per-cpu definitions"
971 depends on DEBUG_KERNEL
972 help
973 s390 and alpha require percpu variables in modules to be
974 defined weak to work around addressing range issue which
975 puts the following two restrictions on percpu variable
976 definitions.
978 1. percpu symbols must be unique whether static or not
979 2. percpu variables can't be defined inside a function
981 To ensure that generic code follows the above rules, this
982 option forces all percpu variables to be defined as weak.
984 config LKDTM
985 tristate "Linux Kernel Dump Test Tool Module"
986 depends on DEBUG_FS
987 depends on BLOCK
988 default n
989 help
990 This module enables testing of the different dumping mechanisms by
991 inducing system failures at predefined crash points.
992 If you don't need it: say N
993 Choose M here to compile this code as a module. The module will be
994 called lkdtm.
996 Documentation on how to use the module can be found in
997 Documentation/fault-injection/provoke-crashes.txt
999 config CPU_NOTIFIER_ERROR_INJECT
1000 tristate "CPU notifier error injection module"
1001 depends on HOTPLUG_CPU && DEBUG_KERNEL
1002 help
1003 This option provides a kernel module that can be used to test
1004 the error handling of the cpu notifiers
1006 To compile this code as a module, choose M here: the module will
1007 be called cpu-notifier-error-inject.
1009 If unsure, say N.
1011 config FAULT_INJECTION
1012 bool "Fault-injection framework"
1013 depends on DEBUG_KERNEL
1014 help
1015 Provide fault-injection framework.
1016 For more details, see Documentation/fault-injection/.
1018 config FAILSLAB
1019 bool "Fault-injection capability for kmalloc"
1020 depends on FAULT_INJECTION
1021 depends on SLAB || SLUB
1022 help
1023 Provide fault-injection capability for kmalloc.
1025 config FAIL_PAGE_ALLOC
1026 bool "Fault-injection capabilitiy for alloc_pages()"
1027 depends on FAULT_INJECTION
1028 help
1029 Provide fault-injection capability for alloc_pages().
1031 config FAIL_MAKE_REQUEST
1032 bool "Fault-injection capability for disk IO"
1033 depends on FAULT_INJECTION && BLOCK
1034 help
1035 Provide fault-injection capability for disk IO.
1037 config FAIL_IO_TIMEOUT
1038 bool "Fault-injection capability for faking disk interrupts"
1039 depends on FAULT_INJECTION && BLOCK
1040 help
1041 Provide fault-injection capability on end IO handling. This
1042 will make the block layer "forget" an interrupt as configured,
1043 thus exercising the error handling.
1045 Only works with drivers that use the generic timeout handling,
1046 for others it wont do anything.
1048 config FAULT_INJECTION_DEBUG_FS
1049 bool "Debugfs entries for fault-injection capabilities"
1050 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1051 help
1052 Enable configuration of fault-injection capabilities via debugfs.
1054 config FAULT_INJECTION_STACKTRACE_FILTER
1055 bool "stacktrace filter for fault-injection capabilities"
1056 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1057 depends on !X86_64
1058 select STACKTRACE
1059 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
1060 help
1061 Provide stacktrace filter for fault-injection capabilities
1063 config LATENCYTOP
1064 bool "Latency measuring infrastructure"
1065 depends on HAVE_LATENCYTOP_SUPPORT
1066 depends on DEBUG_KERNEL
1067 depends on STACKTRACE_SUPPORT
1068 depends on PROC_FS
1069 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
1070 select KALLSYMS
1071 select KALLSYMS_ALL
1072 select STACKTRACE
1073 select SCHEDSTATS
1074 select SCHED_DEBUG
1075 help
1076 Enable this option if you want to use the LatencyTOP tool
1077 to find out which userspace is blocking on what kernel operations.
1079 config SYSCTL_SYSCALL_CHECK
1080 bool "Sysctl checks"
1081 depends on SYSCTL
1082 ---help---
1083 sys_sysctl uses binary paths that have been found challenging
1084 to properly maintain and use. This enables checks that help
1085 you to keep things correct.
1087 source mm/Kconfig.debug
1088 source kernel/trace/Kconfig
1090 config PROVIDE_OHCI1394_DMA_INIT
1091 bool "Remote debugging over FireWire early on boot"
1092 depends on PCI && X86
1093 help
1094 If you want to debug problems which hang or crash the kernel early
1095 on boot and the crashing machine has a FireWire port, you can use
1096 this feature to remotely access the memory of the crashed machine
1097 over FireWire. This employs remote DMA as part of the OHCI1394
1098 specification which is now the standard for FireWire controllers.
1100 With remote DMA, you can monitor the printk buffer remotely using
1101 firescope and access all memory below 4GB using fireproxy from gdb.
1102 Even controlling a kernel debugger is possible using remote DMA.
1104 Usage:
1106 If ohci1394_dma=early is used as boot parameter, it will initialize
1107 all OHCI1394 controllers which are found in the PCI config space.
1109 As all changes to the FireWire bus such as enabling and disabling
1110 devices cause a bus reset and thereby disable remote DMA for all
1111 devices, be sure to have the cable plugged and FireWire enabled on
1112 the debugging host before booting the debug target for debugging.
1114 This code (~1k) is freed after boot. By then, the firewire stack
1115 in charge of the OHCI-1394 controllers should be used instead.
1117 See Documentation/debugging-via-ohci1394.txt for more information.
1119 config FIREWIRE_OHCI_REMOTE_DMA
1120 bool "Remote debugging over FireWire with firewire-ohci"
1121 depends on FIREWIRE_OHCI
1122 help
1123 This option lets you use the FireWire bus for remote debugging
1124 with help of the firewire-ohci driver. It enables unfiltered
1125 remote DMA in firewire-ohci.
1126 See Documentation/debugging-via-ohci1394.txt for more information.
1128 If unsure, say N.
1130 config BUILD_DOCSRC
1131 bool "Build targets in Documentation/ tree"
1132 depends on HEADERS_CHECK
1133 help
1134 This option attempts to build objects from the source files in the
1135 kernel Documentation/ tree.
1137 Say N if you are unsure.
1139 config DYNAMIC_DEBUG
1140 bool "Enable dynamic printk() support"
1141 default n
1142 depends on PRINTK
1143 depends on DEBUG_FS
1144 help
1146 Compiles debug level messages into the kernel, which would not
1147 otherwise be available at runtime. These messages can then be
1148 enabled/disabled based on various levels of scope - per source file,
1149 function, module, format string, and line number. This mechanism
1150 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1151 this compile option is a larger kernel text size of about 2%.
1153 Usage:
1155 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1156 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1157 filesystem must first be mounted before making use of this feature.
1158 We refer the control file as: <debugfs>/dynamic_debug/control. This
1159 file contains a list of the debug statements that can be enabled. The
1160 format for each line of the file is:
1162 filename:lineno [module]function flags format
1164 filename : source file of the debug statement
1165 lineno : line number of the debug statement
1166 module : module that contains the debug statement
1167 function : function that contains the debug statement
1168 flags : 'p' means the line is turned 'on' for printing
1169 format : the format used for the debug statement
1171 From a live system:
1173 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1174 # filename:lineno [module]function flags format
1175 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1176 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1177 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1179 Example usage:
1181 // enable the message at line 1603 of file svcsock.c
1182 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1183 <debugfs>/dynamic_debug/control
1185 // enable all the messages in file svcsock.c
1186 nullarbor:~ # echo -n 'file svcsock.c +p' >
1187 <debugfs>/dynamic_debug/control
1189 // enable all the messages in the NFS server module
1190 nullarbor:~ # echo -n 'module nfsd +p' >
1191 <debugfs>/dynamic_debug/control
1193 // enable all 12 messages in the function svc_process()
1194 nullarbor:~ # echo -n 'func svc_process +p' >
1195 <debugfs>/dynamic_debug/control
1197 // disable all 12 messages in the function svc_process()
1198 nullarbor:~ # echo -n 'func svc_process -p' >
1199 <debugfs>/dynamic_debug/control
1201 See Documentation/dynamic-debug-howto.txt for additional information.
1203 config DMA_API_DEBUG
1204 bool "Enable debugging of DMA-API usage"
1205 depends on HAVE_DMA_API_DEBUG
1206 help
1207 Enable this option to debug the use of the DMA API by device drivers.
1208 With this option you will be able to detect common bugs in device
1209 drivers like double-freeing of DMA mappings or freeing mappings that
1210 were never allocated.
1211 This option causes a performance degredation. Use only if you want
1212 to debug device drivers. If unsure, say N.
1214 config ATOMIC64_SELFTEST
1215 bool "Perform an atomic64_t self-test at boot"
1216 help
1217 Enable this option to test the atomic64_t functions at boot.
1219 If unsure, say N.
1221 config ASYNC_RAID6_TEST
1222 tristate "Self test for hardware accelerated raid6 recovery"
1223 depends on ASYNC_RAID6_RECOV
1224 select ASYNC_MEMCPY
1225 ---help---
1226 This is a one-shot self test that permutes through the
1227 recovery of all the possible two disk failure scenarios for a
1228 N-disk array. Recovery is performed with the asynchronous
1229 raid6 recovery routines, and will optionally use an offload
1230 engine if one is available.
1232 If unsure, say N.
1234 source "samples/Kconfig"
1236 source "lib/Kconfig.kgdb"
1238 source "lib/Kconfig.kmemcheck"