3 bool "Show timing information on printks"
6 Selecting this option causes timing information to be
7 included in printk output. This allows you to measure
8 the interval between kernel operations, including bootup
9 operations. This is useful for identifying long delays
10 in kernel startup. Or add printk.time=1 at boot-time.
11 See Documentation/kernel-parameters.txt
13 config ENABLE_WARN_DEPRECATED
14 bool "Enable __deprecated logic"
17 Enable the __deprecated logic in the kernel build.
18 Disable this to suppress the "warning: 'foo' is deprecated
19 (declared at kernel/power/somefile.c:1234)" messages.
21 config ENABLE_MUST_CHECK
22 bool "Enable __must_check logic"
25 Enable the __must_check logic in the kernel build. Disable this to
26 suppress the "warning: ignoring return value of 'foo', declared with
27 attribute warn_unused_result" messages.
30 int "Warn for stack frames larger than (needs gcc 4.4)"
32 default 1024 if !64BIT
35 Tell gcc to warn at build time for stack frames larger than this.
36 Setting this too low will cause a lot of warnings.
37 Setting it to 0 disables the warning.
41 bool "Magic SysRq key"
44 If you say Y here, you will have some control over the system even
45 if the system crashes for example during kernel debugging (e.g., you
46 will be able to flush the buffer cache to disk, reboot the system
47 immediately or dump some status information). This is accomplished
48 by pressing various keys while holding SysRq (Alt+PrintScreen). It
49 also works on a serial console (on PC hardware at least), if you
50 send a BREAK and then within 5 seconds a command keypress. The
51 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
52 unless you really know what this hack does.
55 bool "Strip assembler-generated symbols during link"
58 Strip internal assembler-generated symbols during a link (symbols
59 that look like '.Lxxx') so they don't pollute the output of
60 get_wchan() and suchlike.
63 bool "Enable unused/obsolete exported symbols"
66 Unused but exported symbols make the kernel needlessly bigger. For
67 that reason most of these unused exports will soon be removed. This
68 option is provided temporarily to provide a transition period in case
69 some external kernel module needs one of these symbols anyway. If you
70 encounter such a case in your module, consider if you are actually
71 using the right API. (rationale: since nobody in the kernel is using
72 this in a module, there is a pretty good chance it's actually the
73 wrong interface to use). If you really need the symbol, please send a
74 mail to the linux kernel mailing list mentioning the symbol and why
75 you really need it, and what the merge plan to the mainline kernel for
79 bool "Debug Filesystem"
81 debugfs is a virtual file system that kernel developers use to put
82 debugging files into. Enable this option to be able to read and
85 For detailed documentation on the debugfs API, see
86 Documentation/DocBook/filesystems.
91 bool "Run 'make headers_check' when building vmlinux"
94 This option will extract the user-visible kernel headers whenever
95 building the kernel, and will run basic sanity checks on them to
96 ensure that exported files do not attempt to include files which
97 were not exported, etc.
99 If you're making modifications to header files which are
100 relevant for userspace, say 'Y', and check the headers
101 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
102 your build tree), to make sure they're suitable.
104 config DEBUG_SECTION_MISMATCH
105 bool "Enable full Section mismatch analysis"
106 depends on UNDEFINED || (BLACKFIN)
108 # This option is on purpose disabled for now.
109 # It will be enabled when we are down to a reasonable number
110 # of section mismatch warnings (< 10 for an allyesconfig build)
112 The section mismatch analysis checks if there are illegal
113 references from one section to another section.
114 Linux will during link or during runtime drop some sections
115 and any use of code/data previously in these sections will
116 most likely result in an oops.
117 In the code functions and variables are annotated with
118 __init, __devinit etc. (see full list in include/linux/init.h)
119 which results in the code/data being placed in specific sections.
120 The section mismatch analysis is always done after a full
121 kernel build but enabling this option will in addition
123 - Add the option -fno-inline-functions-called-once to gcc
124 When inlining a function annotated __init in a non-init
125 function we would lose the section information and thus
126 the analysis would not catch the illegal reference.
127 This option tells gcc to inline less but will also
128 result in a larger kernel.
129 - Run the section mismatch analysis for each module/built-in.o
130 When we run the section mismatch analysis on vmlinux.o we
131 lose valueble information about where the mismatch was
133 Running the analysis for each module/built-in.o file
134 will tell where the mismatch happens much closer to the
135 source. The drawback is that we will report the same
136 mismatch at least twice.
137 - Enable verbose reporting from modpost to help solving
138 the section mismatches reported.
141 bool "Kernel debugging"
143 Say Y here if you are developing drivers or trying to debug and
144 identify kernel problems.
147 bool "Debug shared IRQ handlers"
148 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
150 Enable this to generate a spurious interrupt as soon as a shared
151 interrupt handler is registered, and just before one is deregistered.
152 Drivers ought to be able to handle interrupts coming in at those
153 points; some don't and need to be caught.
155 config LOCKUP_DETECTOR
156 bool "Detect Hard and Soft Lockups"
157 depends on DEBUG_KERNEL && !S390
159 Say Y here to enable the kernel to act as a watchdog to detect
160 hard and soft lockups.
162 Softlockups are bugs that cause the kernel to loop in kernel
163 mode for more than 60 seconds, without giving other tasks a
164 chance to run. The current stack trace is displayed upon
165 detection and the system will stay locked up.
167 Hardlockups are bugs that cause the CPU to loop in kernel mode
168 for more than 60 seconds, without letting other interrupts have a
169 chance to run. The current stack trace is displayed upon detection
170 and the system will stay locked up.
172 The overhead should be minimal. A periodic hrtimer runs to
173 generate interrupts and kick the watchdog task every 10-12 seconds.
174 An NMI is generated every 60 seconds or so to check for hardlockups.
176 config HARDLOCKUP_DETECTOR
177 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
178 !ARCH_HAS_NMI_WATCHDOG
180 config BOOTPARAM_SOFTLOCKUP_PANIC
181 bool "Panic (Reboot) On Soft Lockups"
182 depends on LOCKUP_DETECTOR
184 Say Y here to enable the kernel to panic on "soft lockups",
185 which are bugs that cause the kernel to loop in kernel
186 mode for more than 60 seconds, without giving other tasks a
189 The panic can be used in combination with panic_timeout,
190 to cause the system to reboot automatically after a
191 lockup has been detected. This feature is useful for
192 high-availability systems that have uptime guarantees and
193 where a lockup must be resolved ASAP.
197 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
199 depends on LOCKUP_DETECTOR
201 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
202 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
204 config DETECT_HUNG_TASK
205 bool "Detect Hung Tasks"
206 depends on DEBUG_KERNEL
207 default DETECT_SOFTLOCKUP
209 Say Y here to enable the kernel to detect "hung tasks",
210 which are bugs that cause the task to be stuck in
211 uninterruptible "D" state indefinitiley.
213 When a hung task is detected, the kernel will print the
214 current stack trace (which you should report), but the
215 task will stay in uninterruptible state. If lockdep is
216 enabled then all held locks will also be reported. This
217 feature has negligible overhead.
219 config BOOTPARAM_HUNG_TASK_PANIC
220 bool "Panic (Reboot) On Hung Tasks"
221 depends on DETECT_HUNG_TASK
223 Say Y here to enable the kernel to panic on "hung tasks",
224 which are bugs that cause the kernel to leave a task stuck
225 in uninterruptible "D" state.
227 The panic can be used in combination with panic_timeout,
228 to cause the system to reboot automatically after a
229 hung task has been detected. This feature is useful for
230 high-availability systems that have uptime guarantees and
231 where a hung tasks must be resolved ASAP.
235 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
237 depends on DETECT_HUNG_TASK
239 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
240 default 1 if BOOTPARAM_HUNG_TASK_PANIC
243 bool "Collect scheduler debugging info"
244 depends on DEBUG_KERNEL && PROC_FS
247 If you say Y here, the /proc/sched_debug file will be provided
248 that can help debug the scheduler. The runtime overhead of this
252 bool "Collect scheduler statistics"
253 depends on DEBUG_KERNEL && PROC_FS
255 If you say Y here, additional code will be inserted into the
256 scheduler and related routines to collect statistics about
257 scheduler behavior and provide them in /proc/schedstat. These
258 stats may be useful for both tuning and debugging the scheduler
259 If you aren't debugging the scheduler or trying to tune a specific
260 application, you can say N to avoid the very slight overhead
264 bool "Collect kernel timers statistics"
265 depends on DEBUG_KERNEL && PROC_FS
267 If you say Y here, additional code will be inserted into the
268 timer routines to collect statistics about kernel timers being
269 reprogrammed. The statistics can be read from /proc/timer_stats.
270 The statistics collection is started by writing 1 to /proc/timer_stats,
271 writing 0 stops it. This feature is useful to collect information
272 about timer usage patterns in kernel and userspace. This feature
273 is lightweight if enabled in the kernel config but not activated
274 (it defaults to deactivated on bootup and will only be activated
275 if some application like powertop activates it explicitly).
278 bool "Debug object operations"
279 depends on DEBUG_KERNEL
281 If you say Y here, additional code will be inserted into the
282 kernel to track the life time of various objects and validate
283 the operations on those objects.
285 config DEBUG_OBJECTS_SELFTEST
286 bool "Debug objects selftest"
287 depends on DEBUG_OBJECTS
289 This enables the selftest of the object debug code.
291 config DEBUG_OBJECTS_FREE
292 bool "Debug objects in freed memory"
293 depends on DEBUG_OBJECTS
295 This enables checks whether a k/v free operation frees an area
296 which contains an object which has not been deactivated
297 properly. This can make kmalloc/kfree-intensive workloads
300 config DEBUG_OBJECTS_TIMERS
301 bool "Debug timer objects"
302 depends on DEBUG_OBJECTS
304 If you say Y here, additional code will be inserted into the
305 timer routines to track the life time of timer objects and
306 validate the timer operations.
308 config DEBUG_OBJECTS_WORK
309 bool "Debug work objects"
310 depends on DEBUG_OBJECTS
312 If you say Y here, additional code will be inserted into the
313 work queue routines to track the life time of work objects and
314 validate the work operations.
316 config DEBUG_OBJECTS_RCU_HEAD
317 bool "Debug RCU callbacks objects"
318 depends on DEBUG_OBJECTS && PREEMPT
320 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
322 config DEBUG_OBJECTS_PERCPU_COUNTER
323 bool "Debug percpu counter objects"
324 depends on DEBUG_OBJECTS
326 If you say Y here, additional code will be inserted into the
327 percpu counter routines to track the life time of percpu counter
328 objects and validate the percpu counter operations.
330 config DEBUG_OBJECTS_ENABLE_DEFAULT
331 int "debug_objects bootup default value (0-1)"
334 depends on DEBUG_OBJECTS
336 Debug objects boot parameter default value
339 bool "Debug slab memory allocations"
340 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
342 Say Y here to have the kernel do limited verification on memory
343 allocation as well as poisoning memory on free to catch use of freed
344 memory. This can make kmalloc/kfree-intensive workloads much slower.
346 config DEBUG_SLAB_LEAK
347 bool "Memory leak debugging"
348 depends on DEBUG_SLAB
351 bool "SLUB debugging on by default"
352 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
355 Boot with debugging on by default. SLUB boots by default with
356 the runtime debug capabilities switched off. Enabling this is
357 equivalent to specifying the "slub_debug" parameter on boot.
358 There is no support for more fine grained debug control like
359 possible with slub_debug=xxx. SLUB debugging may be switched
360 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
365 bool "Enable SLUB performance statistics"
366 depends on SLUB && SYSFS
368 SLUB statistics are useful to debug SLUBs allocation behavior in
369 order find ways to optimize the allocator. This should never be
370 enabled for production use since keeping statistics slows down
371 the allocator by a few percentage points. The slabinfo command
372 supports the determination of the most active slabs to figure
373 out which slabs are relevant to a particular load.
374 Try running: slabinfo -DA
376 config DEBUG_KMEMLEAK
377 bool "Kernel memory leak detector"
378 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
379 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
381 select DEBUG_FS if SYSFS
382 select STACKTRACE if STACKTRACE_SUPPORT
386 Say Y here if you want to enable the memory leak
387 detector. The memory allocation/freeing is traced in a way
388 similar to the Boehm's conservative garbage collector, the
389 difference being that the orphan objects are not freed but
390 only shown in /sys/kernel/debug/kmemleak. Enabling this
391 feature will introduce an overhead to memory
392 allocations. See Documentation/kmemleak.txt for more
395 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
396 of finding leaks due to the slab objects poisoning.
398 In order to access the kmemleak file, debugfs needs to be
399 mounted (usually at /sys/kernel/debug).
401 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
402 int "Maximum kmemleak early log entries"
403 depends on DEBUG_KMEMLEAK
407 Kmemleak must track all the memory allocations to avoid
408 reporting false positives. Since memory may be allocated or
409 freed before kmemleak is initialised, an early log buffer is
410 used to store these actions. If kmemleak reports "early log
411 buffer exceeded", please increase this value.
413 config DEBUG_KMEMLEAK_TEST
414 tristate "Simple test for the kernel memory leak detector"
415 depends on DEBUG_KMEMLEAK
417 Say Y or M here to build a test for the kernel memory leak
418 detector. This option enables a module that explicitly leaks
423 config DEBUG_KMEMLEAK_DEFAULT_OFF
424 bool "Default kmemleak to off"
425 depends on DEBUG_KMEMLEAK
427 Say Y here to disable kmemleak by default. It can then be enabled
428 on the command line via kmemleak=on.
431 bool "Debug preemptible kernel"
432 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
435 If you say Y here then the kernel will use a debug variant of the
436 commonly used smp_processor_id() function and will print warnings
437 if kernel code uses it in a preemption-unsafe way. Also, the kernel
438 will detect preemption count underflows.
440 config DEBUG_RT_MUTEXES
441 bool "RT Mutex debugging, deadlock detection"
442 depends on DEBUG_KERNEL && RT_MUTEXES
444 This allows rt mutex semantics violations and rt mutex related
445 deadlocks (lockups) to be detected and reported automatically.
450 depends on DEBUG_RT_MUTEXES
452 config RT_MUTEX_TESTER
453 bool "Built-in scriptable tester for rt-mutexes"
454 depends on DEBUG_KERNEL && RT_MUTEXES
456 This option enables a rt-mutex tester.
458 config DEBUG_SPINLOCK
459 bool "Spinlock and rw-lock debugging: basic checks"
460 depends on DEBUG_KERNEL
462 Say Y here and build SMP to catch missing spinlock initialization
463 and certain other kinds of spinlock errors commonly made. This is
464 best used in conjunction with the NMI watchdog so that spinlock
465 deadlocks are also debuggable.
468 bool "Mutex debugging: basic checks"
469 depends on DEBUG_KERNEL
471 This feature allows mutex semantics violations to be detected and
474 config DEBUG_LOCK_ALLOC
475 bool "Lock debugging: detect incorrect freeing of live locks"
476 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
477 select DEBUG_SPINLOCK
481 This feature will check whether any held lock (spinlock, rwlock,
482 mutex or rwsem) is incorrectly freed by the kernel, via any of the
483 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
484 vfree(), etc.), whether a live lock is incorrectly reinitialized via
485 spin_lock_init()/mutex_init()/etc., or whether there is any lock
486 held during task exit.
489 bool "Lock debugging: prove locking correctness"
490 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
492 select DEBUG_SPINLOCK
494 select DEBUG_LOCK_ALLOC
495 select TRACE_IRQFLAGS
498 This feature enables the kernel to prove that all locking
499 that occurs in the kernel runtime is mathematically
500 correct: that under no circumstance could an arbitrary (and
501 not yet triggered) combination of observed locking
502 sequences (on an arbitrary number of CPUs, running an
503 arbitrary number of tasks and interrupt contexts) cause a
506 In short, this feature enables the kernel to report locking
507 related deadlocks before they actually occur.
509 The proof does not depend on how hard and complex a
510 deadlock scenario would be to trigger: how many
511 participant CPUs, tasks and irq-contexts would be needed
512 for it to trigger. The proof also does not depend on
513 timing: if a race and a resulting deadlock is possible
514 theoretically (no matter how unlikely the race scenario
515 is), it will be proven so and will immediately be
516 reported by the kernel (once the event is observed that
517 makes the deadlock theoretically possible).
519 If a deadlock is impossible (i.e. the locking rules, as
520 observed by the kernel, are mathematically correct), the
521 kernel reports nothing.
523 NOTE: this feature can also be enabled for rwlocks, mutexes
524 and rwsems - in which case all dependencies between these
525 different locking variants are observed and mapped too, and
526 the proof of observed correctness is also maintained for an
527 arbitrary combination of these separate locking variants.
529 For more details, see Documentation/lockdep-design.txt.
532 bool "RCU debugging: prove RCU correctness"
533 depends on PROVE_LOCKING
536 This feature enables lockdep extensions that check for correct
537 use of RCU APIs. This is currently under development. Say Y
538 if you want to debug RCU usage or help work on the PROVE_RCU
541 Say N if you are unsure.
543 config PROVE_RCU_REPEATEDLY
544 bool "RCU debugging: don't disable PROVE_RCU on first splat"
548 By itself, PROVE_RCU will disable checking upon issuing the
549 first warning (or "splat"). This feature prevents such
550 disabling, allowing multiple RCU-lockdep warnings to be printed
553 Say Y to allow multiple RCU-lockdep warnings per boot.
555 Say N if you are unsure.
557 config SPARSE_RCU_POINTER
558 bool "RCU debugging: sparse-based checks for pointer usage"
561 This feature enables the __rcu sparse annotation for
562 RCU-protected pointers. This annotation will cause sparse
563 to flag any non-RCU used of annotated pointers. This can be
564 helpful when debugging RCU usage. Please note that this feature
565 is not intended to enforce code cleanliness; it is instead merely
568 Say Y to make sparse flag questionable use of RCU-protected pointers
570 Say N if you are unsure.
574 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
576 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
581 bool "Lock usage statistics"
582 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
584 select DEBUG_SPINLOCK
586 select DEBUG_LOCK_ALLOC
589 This feature enables tracking lock contention points
591 For more details, see Documentation/lockstat.txt
593 This also enables lock events required by "perf lock",
595 If you want to use "perf lock", you also need to turn on
596 CONFIG_EVENT_TRACING.
598 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
599 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
602 bool "Lock dependency engine debugging"
603 depends on DEBUG_KERNEL && LOCKDEP
605 If you say Y here, the lock dependency engine will do
606 additional runtime checks to debug itself, at the price
607 of more runtime overhead.
609 config TRACE_IRQFLAGS
612 Enables hooks to interrupt enabling and disabling for
613 either tracing or lock debugging.
615 config DEBUG_SPINLOCK_SLEEP
616 bool "Spinlock debugging: sleep-inside-spinlock checking"
617 depends on DEBUG_KERNEL
619 If you say Y here, various routines which may sleep will become very
620 noisy if they are called with a spinlock held.
622 config DEBUG_LOCKING_API_SELFTESTS
623 bool "Locking API boot-time self-tests"
624 depends on DEBUG_KERNEL
626 Say Y here if you want the kernel to run a short self-test during
627 bootup. The self-test checks whether common types of locking bugs
628 are detected by debugging mechanisms or not. (if you disable
629 lock debugging then those bugs wont be detected of course.)
630 The following locking APIs are covered: spinlocks, rwlocks,
635 depends on STACKTRACE_SUPPORT
638 bool "kobject debugging"
639 depends on DEBUG_KERNEL
641 If you say Y here, some extra kobject debugging messages will be sent
645 bool "Highmem debugging"
646 depends on DEBUG_KERNEL && HIGHMEM
648 This options enables addition error checking for high memory systems.
649 Disable for production systems.
651 config DEBUG_BUGVERBOSE
652 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
654 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
655 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
658 Say Y here to make BUG() panics output the file name and line number
659 of the BUG call as well as the EIP and oops trace. This aids
660 debugging but costs about 70-100K of memory.
663 bool "Compile the kernel with debug info"
664 depends on DEBUG_KERNEL
666 If you say Y here the resulting kernel image will include
667 debugging info resulting in a larger kernel image.
668 This adds debug symbols to the kernel and modules (gcc -g), and
669 is needed if you intend to use kernel crashdump or binary object
670 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
671 Say Y here only if you plan to debug the kernel.
675 config DEBUG_INFO_REDUCED
676 bool "Reduce debugging information"
677 depends on DEBUG_INFO
679 If you say Y here gcc is instructed to generate less debugging
680 information for structure types. This means that tools that
681 need full debugging information (like kgdb or systemtap) won't
682 be happy. But if you merely need debugging information to
683 resolve line numbers there is no loss. Advantage is that
684 build directory object sizes shrink dramatically over a full
685 DEBUG_INFO build and compile times are reduced too.
686 Only works with newer gcc versions.
690 depends on DEBUG_KERNEL
692 Enable this to turn on extended checks in the virtual-memory system
693 that may impact performance.
698 bool "Debug VM translations"
699 depends on DEBUG_KERNEL && X86
701 Enable some costly sanity checks in virtual to page code. This can
702 catch mistakes with virt_to_page() and friends.
706 config DEBUG_NOMMU_REGIONS
707 bool "Debug the global anon/private NOMMU mapping region tree"
708 depends on DEBUG_KERNEL && !MMU
710 This option causes the global tree of anonymous and private mapping
711 regions to be regularly checked for invalid topology.
713 config DEBUG_WRITECOUNT
714 bool "Debug filesystem writers count"
715 depends on DEBUG_KERNEL
717 Enable this to catch wrong use of the writers count in struct
718 vfsmount. This will increase the size of each file struct by
723 config DEBUG_MEMORY_INIT
724 bool "Debug memory initialisation" if EXPERT
727 Enable this for additional checks during memory initialisation.
728 The sanity checks verify aspects of the VM such as the memory model
729 and other information provided by the architecture. Verbose
730 information will be printed at KERN_DEBUG loglevel depending
731 on the mminit_loglevel= command-line option.
736 bool "Debug linked list manipulation"
737 depends on DEBUG_KERNEL
739 Enable this to turn on extended checks in the linked-list
744 config TEST_LIST_SORT
745 bool "Linked list sorting test"
746 depends on DEBUG_KERNEL
748 Enable this to turn on 'list_sort()' function test. This test is
749 executed only once during system boot, so affects only boot time.
754 bool "Debug SG table operations"
755 depends on DEBUG_KERNEL
757 Enable this to turn on checks on scatter-gather tables. This can
758 help find problems with drivers that do not properly initialize
763 config DEBUG_NOTIFIERS
764 bool "Debug notifier call chains"
765 depends on DEBUG_KERNEL
767 Enable this to turn on sanity checking for notifier call chains.
768 This is most useful for kernel developers to make sure that
769 modules properly unregister themselves from notifier chains.
770 This is a relatively cheap check but if you care about maximum
773 config DEBUG_CREDENTIALS
774 bool "Debug credential management"
775 depends on DEBUG_KERNEL
777 Enable this to turn on some debug checking for credential
778 management. The additional code keeps track of the number of
779 pointers from task_structs to any given cred struct, and checks to
780 see that this number never exceeds the usage count of the cred
783 Furthermore, if SELinux is enabled, this also checks that the
784 security pointer in the cred struct is never seen to be invalid.
789 # Select this config option from the architecture Kconfig, if it
790 # it is preferred to always offer frame pointers as a config
791 # option on the architecture (regardless of KERNEL_DEBUG):
793 config ARCH_WANT_FRAME_POINTERS
798 bool "Compile the kernel with frame pointers"
799 depends on DEBUG_KERNEL && \
800 (CRIS || M68K || FRV || UML || \
801 AVR32 || SUPERH || BLACKFIN || MN10300) || \
802 ARCH_WANT_FRAME_POINTERS
803 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
805 If you say Y here the resulting kernel image will be slightly
806 larger and slower, but it gives very useful debugging information
807 in case of kernel bugs. (precise oopses/stacktraces/warnings)
809 config BOOT_PRINTK_DELAY
810 bool "Delay each boot printk message by N milliseconds"
811 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
813 This build option allows you to read kernel boot messages
814 by inserting a short delay after each one. The delay is
815 specified in milliseconds on the kernel command line,
816 using "boot_delay=N".
818 It is likely that you would also need to use "lpj=M" to preset
819 the "loops per jiffie" value.
820 See a previous boot log for the "lpj" value to use for your
821 system, and then set "lpj=M" before setting "boot_delay=N".
822 NOTE: Using this option may adversely affect SMP systems.
823 I.e., processors other than the first one may not boot up.
824 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
825 what it believes to be lockup conditions.
827 config RCU_TORTURE_TEST
828 tristate "torture tests for RCU"
829 depends on DEBUG_KERNEL
832 This option provides a kernel module that runs torture tests
833 on the RCU infrastructure. The kernel module may be built
834 after the fact on the running kernel to be tested, if desired.
836 Say Y here if you want RCU torture tests to be built into
838 Say M if you want the RCU torture tests to build as a module.
839 Say N if you are unsure.
841 config RCU_TORTURE_TEST_RUNNABLE
842 bool "torture tests for RCU runnable by default"
843 depends on RCU_TORTURE_TEST = y
846 This option provides a way to build the RCU torture tests
847 directly into the kernel without them starting up at boot
848 time. You can use /proc/sys/kernel/rcutorture_runnable
849 to manually override this setting. This /proc file is
850 available only when the RCU torture tests have been built
853 Say Y here if you want the RCU torture tests to start during
854 boot (you probably don't).
855 Say N here if you want the RCU torture tests to start only
856 after being manually enabled via /proc.
858 config RCU_CPU_STALL_DETECTOR
859 bool "Check for stalled CPUs delaying RCU grace periods"
860 depends on TREE_RCU || TREE_PREEMPT_RCU
863 This option causes RCU to printk information on which
864 CPUs are delaying the current grace period, but only when
865 the grace period extends for excessive time periods.
867 Say N if you want to disable such checks.
869 Say Y if you are unsure.
871 config RCU_CPU_STALL_TIMEOUT
872 int "RCU CPU stall timeout in seconds"
873 depends on RCU_CPU_STALL_DETECTOR
877 If a given RCU grace period extends more than the specified
878 number of seconds, a CPU stall warning is printed. If the
879 RCU grace period persists, additional CPU stall warnings are
880 printed at more widely spaced intervals.
882 config RCU_CPU_STALL_DETECTOR_RUNNABLE
883 bool "RCU CPU stall checking starts automatically at boot"
884 depends on RCU_CPU_STALL_DETECTOR
887 If set, start checking for RCU CPU stalls immediately on
888 boot. Otherwise, RCU CPU stall checking must be manually
891 Say Y if you are unsure.
893 Say N if you wish to suppress RCU CPU stall checking during boot.
895 config RCU_CPU_STALL_VERBOSE
896 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
897 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
900 This option causes RCU to printk detailed per-task information
901 for any tasks that are stalling the current RCU grace period.
903 Say N if you are unsure.
905 Say Y if you want to enable such checks.
907 config KPROBES_SANITY_TEST
908 bool "Kprobes sanity tests"
909 depends on DEBUG_KERNEL
913 This option provides for testing basic kprobes functionality on
914 boot. A sample kprobe, jprobe and kretprobe are inserted and
915 verified for functionality.
917 Say N if you are unsure.
919 config BACKTRACE_SELF_TEST
920 tristate "Self test for the backtrace code"
921 depends on DEBUG_KERNEL
924 This option provides a kernel module that can be used to test
925 the kernel stack backtrace code. This option is not useful
926 for distributions or general kernels, but only for kernel
927 developers working on architecture code.
929 Note that if you want to also test saved backtraces, you will
930 have to enable STACKTRACE as well.
932 Say N if you are unsure.
934 config DEBUG_BLOCK_EXT_DEVT
935 bool "Force extended block device numbers and spread them"
936 depends on DEBUG_KERNEL
940 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
941 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
942 YOU ARE DOING. Distros, please enable this and fix whatever
945 Conventionally, block device numbers are allocated from
946 predetermined contiguous area. However, extended block area
947 may introduce non-contiguous block device numbers. This
948 option forces most block device numbers to be allocated from
949 the extended space and spreads them to discover kernel or
950 userland code paths which assume predetermined contiguous
951 device number allocation.
953 Note that turning on this debug option shuffles all the
954 device numbers for all IDE and SCSI devices including libata
955 ones, so root partition specified using device number
956 directly (via rdev or root=MAJ:MIN) won't work anymore.
957 Textual device names (root=/dev/sdXn) will continue to work.
959 Say N if you are unsure.
961 config DEBUG_FORCE_WEAK_PER_CPU
962 bool "Force weak per-cpu definitions"
963 depends on DEBUG_KERNEL
965 s390 and alpha require percpu variables in modules to be
966 defined weak to work around addressing range issue which
967 puts the following two restrictions on percpu variable
970 1. percpu symbols must be unique whether static or not
971 2. percpu variables can't be defined inside a function
973 To ensure that generic code follows the above rules, this
974 option forces all percpu variables to be defined as weak.
977 tristate "Linux Kernel Dump Test Tool Module"
982 This module enables testing of the different dumping mechanisms by
983 inducing system failures at predefined crash points.
984 If you don't need it: say N
985 Choose M here to compile this code as a module. The module will be
988 Documentation on how to use the module can be found in
989 Documentation/fault-injection/provoke-crashes.txt
991 config CPU_NOTIFIER_ERROR_INJECT
992 tristate "CPU notifier error injection module"
993 depends on HOTPLUG_CPU && DEBUG_KERNEL
995 This option provides a kernel module that can be used to test
996 the error handling of the cpu notifiers
998 To compile this code as a module, choose M here: the module will
999 be called cpu-notifier-error-inject.
1003 config FAULT_INJECTION
1004 bool "Fault-injection framework"
1005 depends on DEBUG_KERNEL
1007 Provide fault-injection framework.
1008 For more details, see Documentation/fault-injection/.
1011 bool "Fault-injection capability for kmalloc"
1012 depends on FAULT_INJECTION
1013 depends on SLAB || SLUB
1015 Provide fault-injection capability for kmalloc.
1017 config FAIL_PAGE_ALLOC
1018 bool "Fault-injection capabilitiy for alloc_pages()"
1019 depends on FAULT_INJECTION
1021 Provide fault-injection capability for alloc_pages().
1023 config FAIL_MAKE_REQUEST
1024 bool "Fault-injection capability for disk IO"
1025 depends on FAULT_INJECTION && BLOCK
1027 Provide fault-injection capability for disk IO.
1029 config FAIL_IO_TIMEOUT
1030 bool "Fault-injection capability for faking disk interrupts"
1031 depends on FAULT_INJECTION && BLOCK
1033 Provide fault-injection capability on end IO handling. This
1034 will make the block layer "forget" an interrupt as configured,
1035 thus exercising the error handling.
1037 Only works with drivers that use the generic timeout handling,
1038 for others it wont do anything.
1040 config FAULT_INJECTION_DEBUG_FS
1041 bool "Debugfs entries for fault-injection capabilities"
1042 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1044 Enable configuration of fault-injection capabilities via debugfs.
1046 config FAULT_INJECTION_STACKTRACE_FILTER
1047 bool "stacktrace filter for fault-injection capabilities"
1048 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1051 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
1053 Provide stacktrace filter for fault-injection capabilities
1056 bool "Latency measuring infrastructure"
1057 depends on HAVE_LATENCYTOP_SUPPORT
1058 depends on DEBUG_KERNEL
1059 depends on STACKTRACE_SUPPORT
1061 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
1068 Enable this option if you want to use the LatencyTOP tool
1069 to find out which userspace is blocking on what kernel operations.
1071 config SYSCTL_SYSCALL_CHECK
1072 bool "Sysctl checks"
1075 sys_sysctl uses binary paths that have been found challenging
1076 to properly maintain and use. This enables checks that help
1077 you to keep things correct.
1079 source mm/Kconfig.debug
1080 source kernel/trace/Kconfig
1082 config PROVIDE_OHCI1394_DMA_INIT
1083 bool "Remote debugging over FireWire early on boot"
1084 depends on PCI && X86
1086 If you want to debug problems which hang or crash the kernel early
1087 on boot and the crashing machine has a FireWire port, you can use
1088 this feature to remotely access the memory of the crashed machine
1089 over FireWire. This employs remote DMA as part of the OHCI1394
1090 specification which is now the standard for FireWire controllers.
1092 With remote DMA, you can monitor the printk buffer remotely using
1093 firescope and access all memory below 4GB using fireproxy from gdb.
1094 Even controlling a kernel debugger is possible using remote DMA.
1098 If ohci1394_dma=early is used as boot parameter, it will initialize
1099 all OHCI1394 controllers which are found in the PCI config space.
1101 As all changes to the FireWire bus such as enabling and disabling
1102 devices cause a bus reset and thereby disable remote DMA for all
1103 devices, be sure to have the cable plugged and FireWire enabled on
1104 the debugging host before booting the debug target for debugging.
1106 This code (~1k) is freed after boot. By then, the firewire stack
1107 in charge of the OHCI-1394 controllers should be used instead.
1109 See Documentation/debugging-via-ohci1394.txt for more information.
1111 config FIREWIRE_OHCI_REMOTE_DMA
1112 bool "Remote debugging over FireWire with firewire-ohci"
1113 depends on FIREWIRE_OHCI
1115 This option lets you use the FireWire bus for remote debugging
1116 with help of the firewire-ohci driver. It enables unfiltered
1117 remote DMA in firewire-ohci.
1118 See Documentation/debugging-via-ohci1394.txt for more information.
1123 bool "Build targets in Documentation/ tree"
1124 depends on HEADERS_CHECK
1126 This option attempts to build objects from the source files in the
1127 kernel Documentation/ tree.
1129 Say N if you are unsure.
1131 config DYNAMIC_DEBUG
1132 bool "Enable dynamic printk() support"
1138 Compiles debug level messages into the kernel, which would not
1139 otherwise be available at runtime. These messages can then be
1140 enabled/disabled based on various levels of scope - per source file,
1141 function, module, format string, and line number. This mechanism
1142 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1143 this compile option is a larger kernel text size of about 2%.
1147 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1148 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1149 filesystem must first be mounted before making use of this feature.
1150 We refer the control file as: <debugfs>/dynamic_debug/control. This
1151 file contains a list of the debug statements that can be enabled. The
1152 format for each line of the file is:
1154 filename:lineno [module]function flags format
1156 filename : source file of the debug statement
1157 lineno : line number of the debug statement
1158 module : module that contains the debug statement
1159 function : function that contains the debug statement
1160 flags : 'p' means the line is turned 'on' for printing
1161 format : the format used for the debug statement
1165 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1166 # filename:lineno [module]function flags format
1167 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1168 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1169 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1173 // enable the message at line 1603 of file svcsock.c
1174 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1175 <debugfs>/dynamic_debug/control
1177 // enable all the messages in file svcsock.c
1178 nullarbor:~ # echo -n 'file svcsock.c +p' >
1179 <debugfs>/dynamic_debug/control
1181 // enable all the messages in the NFS server module
1182 nullarbor:~ # echo -n 'module nfsd +p' >
1183 <debugfs>/dynamic_debug/control
1185 // enable all 12 messages in the function svc_process()
1186 nullarbor:~ # echo -n 'func svc_process +p' >
1187 <debugfs>/dynamic_debug/control
1189 // disable all 12 messages in the function svc_process()
1190 nullarbor:~ # echo -n 'func svc_process -p' >
1191 <debugfs>/dynamic_debug/control
1193 See Documentation/dynamic-debug-howto.txt for additional information.
1195 config DMA_API_DEBUG
1196 bool "Enable debugging of DMA-API usage"
1197 depends on HAVE_DMA_API_DEBUG
1199 Enable this option to debug the use of the DMA API by device drivers.
1200 With this option you will be able to detect common bugs in device
1201 drivers like double-freeing of DMA mappings or freeing mappings that
1202 were never allocated.
1203 This option causes a performance degredation. Use only if you want
1204 to debug device drivers. If unsure, say N.
1206 config ATOMIC64_SELFTEST
1207 bool "Perform an atomic64_t self-test at boot"
1209 Enable this option to test the atomic64_t functions at boot.
1213 config ASYNC_RAID6_TEST
1214 tristate "Self test for hardware accelerated raid6 recovery"
1215 depends on ASYNC_RAID6_RECOV
1218 This is a one-shot self test that permutes through the
1219 recovery of all the possible two disk failure scenarios for a
1220 N-disk array. Recovery is performed with the asynchronous
1221 raid6 recovery routines, and will optionally use an offload
1222 engine if one is available.
1226 source "samples/Kconfig"
1228 source "lib/Kconfig.kgdb"
1230 source "lib/Kconfig.kmemcheck"