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
12 config ENABLE_WARN_DEPRECATED
13 bool "Enable __deprecated logic"
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"
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.
29 int "Warn for stack frames larger than (needs gcc 4.4)"
31 default 1024 if !64BIT
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.
40 bool "Magic SysRq key"
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.
54 bool "Strip assembler-generated symbols during link"
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.
62 bool "Enable unused/obsolete exported symbols"
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
78 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 DETECT_SOFTLOCKUP
156 bool "Detect Soft Lockups"
157 depends on DEBUG_KERNEL && !S390
160 Say Y here to enable the kernel to detect "soft lockups",
161 which are bugs that cause the kernel to loop in kernel
162 mode for more than 60 seconds, without giving other tasks a
165 When a soft-lockup is detected, the kernel will print the
166 current stack trace (which you should report), but the
167 system will stay locked up. This feature has negligible
170 (Note that "hard lockups" are separate type of bugs that
171 can be detected via the NMI-watchdog, on platforms that
174 config BOOTPARAM_SOFTLOCKUP_PANIC
175 bool "Panic (Reboot) On Soft Lockups"
176 depends on DETECT_SOFTLOCKUP
178 Say Y here to enable the kernel to panic on "soft lockups",
179 which are bugs that cause the kernel to loop in kernel
180 mode for more than 60 seconds, without giving other tasks a
183 The panic can be used in combination with panic_timeout,
184 to cause the system to reboot automatically after a
185 lockup has been detected. This feature is useful for
186 high-availability systems that have uptime guarantees and
187 where a lockup must be resolved ASAP.
191 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
193 depends on DETECT_SOFTLOCKUP
195 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
196 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
198 config DETECT_HUNG_TASK
199 bool "Detect Hung Tasks"
200 depends on DEBUG_KERNEL
201 default DETECT_SOFTLOCKUP
203 Say Y here to enable the kernel to detect "hung tasks",
204 which are bugs that cause the task to be stuck in
205 uninterruptible "D" state indefinitiley.
207 When a hung task is detected, the kernel will print the
208 current stack trace (which you should report), but the
209 task will stay in uninterruptible state. If lockdep is
210 enabled then all held locks will also be reported. This
211 feature has negligible overhead.
213 config BOOTPARAM_HUNG_TASK_PANIC
214 bool "Panic (Reboot) On Hung Tasks"
215 depends on DETECT_HUNG_TASK
217 Say Y here to enable the kernel to panic on "hung tasks",
218 which are bugs that cause the kernel to leave a task stuck
219 in uninterruptible "D" state.
221 The panic can be used in combination with panic_timeout,
222 to cause the system to reboot automatically after a
223 hung task has been detected. This feature is useful for
224 high-availability systems that have uptime guarantees and
225 where a hung tasks must be resolved ASAP.
229 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
231 depends on DETECT_HUNG_TASK
233 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
234 default 1 if BOOTPARAM_HUNG_TASK_PANIC
237 bool "Collect scheduler debugging info"
238 depends on DEBUG_KERNEL && PROC_FS
241 If you say Y here, the /proc/sched_debug file will be provided
242 that can help debug the scheduler. The runtime overhead of this
246 bool "Collect scheduler statistics"
247 depends on DEBUG_KERNEL && PROC_FS
249 If you say Y here, additional code will be inserted into the
250 scheduler and related routines to collect statistics about
251 scheduler behavior and provide them in /proc/schedstat. These
252 stats may be useful for both tuning and debugging the scheduler
253 If you aren't debugging the scheduler or trying to tune a specific
254 application, you can say N to avoid the very slight overhead
258 bool "Collect kernel timers statistics"
259 depends on DEBUG_KERNEL && PROC_FS
261 If you say Y here, additional code will be inserted into the
262 timer routines to collect statistics about kernel timers being
263 reprogrammed. The statistics can be read from /proc/timer_stats.
264 The statistics collection is started by writing 1 to /proc/timer_stats,
265 writing 0 stops it. This feature is useful to collect information
266 about timer usage patterns in kernel and userspace. This feature
267 is lightweight if enabled in the kernel config but not activated
268 (it defaults to deactivated on bootup and will only be activated
269 if some application like powertop activates it explicitly).
272 bool "Debug object operations"
273 depends on DEBUG_KERNEL
275 If you say Y here, additional code will be inserted into the
276 kernel to track the life time of various objects and validate
277 the operations on those objects.
279 config DEBUG_OBJECTS_SELFTEST
280 bool "Debug objects selftest"
281 depends on DEBUG_OBJECTS
283 This enables the selftest of the object debug code.
285 config DEBUG_OBJECTS_FREE
286 bool "Debug objects in freed memory"
287 depends on DEBUG_OBJECTS
289 This enables checks whether a k/v free operation frees an area
290 which contains an object which has not been deactivated
291 properly. This can make kmalloc/kfree-intensive workloads
294 config DEBUG_OBJECTS_TIMERS
295 bool "Debug timer objects"
296 depends on DEBUG_OBJECTS
298 If you say Y here, additional code will be inserted into the
299 timer routines to track the life time of timer objects and
300 validate the timer operations.
302 config DEBUG_OBJECTS_WORK
303 bool "Debug work objects"
304 depends on DEBUG_OBJECTS
306 If you say Y here, additional code will be inserted into the
307 work queue routines to track the life time of work objects and
308 validate the work operations.
310 config DEBUG_OBJECTS_ENABLE_DEFAULT
311 int "debug_objects bootup default value (0-1)"
314 depends on DEBUG_OBJECTS
316 Debug objects boot parameter default value
319 bool "Debug slab memory allocations"
320 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
322 Say Y here to have the kernel do limited verification on memory
323 allocation as well as poisoning memory on free to catch use of freed
324 memory. This can make kmalloc/kfree-intensive workloads much slower.
326 config DEBUG_SLAB_LEAK
327 bool "Memory leak debugging"
328 depends on DEBUG_SLAB
331 bool "SLUB debugging on by default"
332 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
335 Boot with debugging on by default. SLUB boots by default with
336 the runtime debug capabilities switched off. Enabling this is
337 equivalent to specifying the "slub_debug" parameter on boot.
338 There is no support for more fine grained debug control like
339 possible with slub_debug=xxx. SLUB debugging may be switched
340 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
345 bool "Enable SLUB performance statistics"
346 depends on SLUB && SLUB_DEBUG && SYSFS
348 SLUB statistics are useful to debug SLUBs allocation behavior in
349 order find ways to optimize the allocator. This should never be
350 enabled for production use since keeping statistics slows down
351 the allocator by a few percentage points. The slabinfo command
352 supports the determination of the most active slabs to figure
353 out which slabs are relevant to a particular load.
354 Try running: slabinfo -DA
356 config DEBUG_KMEMLEAK
357 bool "Kernel memory leak detector"
358 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
359 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE)
361 select DEBUG_FS if SYSFS
362 select STACKTRACE if STACKTRACE_SUPPORT
366 Say Y here if you want to enable the memory leak
367 detector. The memory allocation/freeing is traced in a way
368 similar to the Boehm's conservative garbage collector, the
369 difference being that the orphan objects are not freed but
370 only shown in /sys/kernel/debug/kmemleak. Enabling this
371 feature will introduce an overhead to memory
372 allocations. See Documentation/kmemleak.txt for more
375 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
376 of finding leaks due to the slab objects poisoning.
378 In order to access the kmemleak file, debugfs needs to be
379 mounted (usually at /sys/kernel/debug).
381 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
382 int "Maximum kmemleak early log entries"
383 depends on DEBUG_KMEMLEAK
387 Kmemleak must track all the memory allocations to avoid
388 reporting false positives. Since memory may be allocated or
389 freed before kmemleak is initialised, an early log buffer is
390 used to store these actions. If kmemleak reports "early log
391 buffer exceeded", please increase this value.
393 config DEBUG_KMEMLEAK_TEST
394 tristate "Simple test for the kernel memory leak detector"
395 depends on DEBUG_KMEMLEAK
397 Say Y or M here to build a test for the kernel memory leak
398 detector. This option enables a module that explicitly leaks
403 config DEBUG_KMEMLEAK_DEFAULT_OFF
404 bool "Default kmemleak to off"
405 depends on DEBUG_KMEMLEAK
407 Say Y here to disable kmemleak by default. It can then be enabled
408 on the command line via kmemleak=on.
411 bool "Debug preemptible kernel"
412 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
415 If you say Y here then the kernel will use a debug variant of the
416 commonly used smp_processor_id() function and will print warnings
417 if kernel code uses it in a preemption-unsafe way. Also, the kernel
418 will detect preemption count underflows.
420 config DEBUG_RT_MUTEXES
421 bool "RT Mutex debugging, deadlock detection"
422 depends on DEBUG_KERNEL && RT_MUTEXES
424 This allows rt mutex semantics violations and rt mutex related
425 deadlocks (lockups) to be detected and reported automatically.
430 depends on DEBUG_RT_MUTEXES
432 config RT_MUTEX_TESTER
433 bool "Built-in scriptable tester for rt-mutexes"
434 depends on DEBUG_KERNEL && RT_MUTEXES
436 This option enables a rt-mutex tester.
438 config DEBUG_SPINLOCK
439 bool "Spinlock and rw-lock debugging: basic checks"
440 depends on DEBUG_KERNEL
442 Say Y here and build SMP to catch missing spinlock initialization
443 and certain other kinds of spinlock errors commonly made. This is
444 best used in conjunction with the NMI watchdog so that spinlock
445 deadlocks are also debuggable.
448 bool "Mutex debugging: basic checks"
449 depends on DEBUG_KERNEL
451 This feature allows mutex semantics violations to be detected and
454 config DEBUG_LOCK_ALLOC
455 bool "Lock debugging: detect incorrect freeing of live locks"
456 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
457 select DEBUG_SPINLOCK
461 This feature will check whether any held lock (spinlock, rwlock,
462 mutex or rwsem) is incorrectly freed by the kernel, via any of the
463 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
464 vfree(), etc.), whether a live lock is incorrectly reinitialized via
465 spin_lock_init()/mutex_init()/etc., or whether there is any lock
466 held during task exit.
469 bool "Lock debugging: prove locking correctness"
470 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
472 select DEBUG_SPINLOCK
474 select DEBUG_LOCK_ALLOC
477 This feature enables the kernel to prove that all locking
478 that occurs in the kernel runtime is mathematically
479 correct: that under no circumstance could an arbitrary (and
480 not yet triggered) combination of observed locking
481 sequences (on an arbitrary number of CPUs, running an
482 arbitrary number of tasks and interrupt contexts) cause a
485 In short, this feature enables the kernel to report locking
486 related deadlocks before they actually occur.
488 The proof does not depend on how hard and complex a
489 deadlock scenario would be to trigger: how many
490 participant CPUs, tasks and irq-contexts would be needed
491 for it to trigger. The proof also does not depend on
492 timing: if a race and a resulting deadlock is possible
493 theoretically (no matter how unlikely the race scenario
494 is), it will be proven so and will immediately be
495 reported by the kernel (once the event is observed that
496 makes the deadlock theoretically possible).
498 If a deadlock is impossible (i.e. the locking rules, as
499 observed by the kernel, are mathematically correct), the
500 kernel reports nothing.
502 NOTE: this feature can also be enabled for rwlocks, mutexes
503 and rwsems - in which case all dependencies between these
504 different locking variants are observed and mapped too, and
505 the proof of observed correctness is also maintained for an
506 arbitrary combination of these separate locking variants.
508 For more details, see Documentation/lockdep-design.txt.
511 bool "RCU debugging: prove RCU correctness"
512 depends on PROVE_LOCKING
515 This feature enables lockdep extensions that check for correct
516 use of RCU APIs. This is currently under development. Say Y
517 if you want to debug RCU usage or help work on the PROVE_RCU
520 Say N if you are unsure.
522 config PROVE_RCU_REPEATEDLY
523 bool "RCU debugging: don't disable PROVE_RCU on first splat"
527 By itself, PROVE_RCU will disable checking upon issuing the
528 first warning (or "splat"). This feature prevents such
529 disabling, allowing multiple RCU-lockdep warnings to be printed
532 Say N if you are unsure.
536 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
538 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
543 bool "Lock usage statistics"
544 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
546 select DEBUG_SPINLOCK
548 select DEBUG_LOCK_ALLOC
551 This feature enables tracking lock contention points
553 For more details, see Documentation/lockstat.txt
555 This also enables lock events required by "perf lock",
557 If you want to use "perf lock", you also need to turn on
558 CONFIG_EVENT_TRACING.
560 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
561 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
564 bool "Lock dependency engine debugging"
565 depends on DEBUG_KERNEL && LOCKDEP
567 If you say Y here, the lock dependency engine will do
568 additional runtime checks to debug itself, at the price
569 of more runtime overhead.
571 config TRACE_IRQFLAGS
572 depends on DEBUG_KERNEL
575 depends on TRACE_IRQFLAGS_SUPPORT
576 depends on PROVE_LOCKING
578 config DEBUG_SPINLOCK_SLEEP
579 bool "Spinlock debugging: sleep-inside-spinlock checking"
580 depends on DEBUG_KERNEL
582 If you say Y here, various routines which may sleep will become very
583 noisy if they are called with a spinlock held.
585 config DEBUG_LOCKING_API_SELFTESTS
586 bool "Locking API boot-time self-tests"
587 depends on DEBUG_KERNEL
589 Say Y here if you want the kernel to run a short self-test during
590 bootup. The self-test checks whether common types of locking bugs
591 are detected by debugging mechanisms or not. (if you disable
592 lock debugging then those bugs wont be detected of course.)
593 The following locking APIs are covered: spinlocks, rwlocks,
598 depends on STACKTRACE_SUPPORT
601 bool "kobject debugging"
602 depends on DEBUG_KERNEL
604 If you say Y here, some extra kobject debugging messages will be sent
608 bool "Highmem debugging"
609 depends on DEBUG_KERNEL && HIGHMEM
611 This options enables addition error checking for high memory systems.
612 Disable for production systems.
614 config DEBUG_BUGVERBOSE
615 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
617 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
618 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
621 Say Y here to make BUG() panics output the file name and line number
622 of the BUG call as well as the EIP and oops trace. This aids
623 debugging but costs about 70-100K of memory.
626 bool "Compile the kernel with debug info"
627 depends on DEBUG_KERNEL
629 If you say Y here the resulting kernel image will include
630 debugging info resulting in a larger kernel image.
631 This adds debug symbols to the kernel and modules (gcc -g), and
632 is needed if you intend to use kernel crashdump or binary object
633 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
634 Say Y here only if you plan to debug the kernel.
640 depends on DEBUG_KERNEL
642 Enable this to turn on extended checks in the virtual-memory system
643 that may impact performance.
648 bool "Debug VM translations"
649 depends on DEBUG_KERNEL && X86
651 Enable some costly sanity checks in virtual to page code. This can
652 catch mistakes with virt_to_page() and friends.
656 config DEBUG_NOMMU_REGIONS
657 bool "Debug the global anon/private NOMMU mapping region tree"
658 depends on DEBUG_KERNEL && !MMU
660 This option causes the global tree of anonymous and private mapping
661 regions to be regularly checked for invalid topology.
663 config DEBUG_WRITECOUNT
664 bool "Debug filesystem writers count"
665 depends on DEBUG_KERNEL
667 Enable this to catch wrong use of the writers count in struct
668 vfsmount. This will increase the size of each file struct by
673 config DEBUG_MEMORY_INIT
674 bool "Debug memory initialisation" if EMBEDDED
677 Enable this for additional checks during memory initialisation.
678 The sanity checks verify aspects of the VM such as the memory model
679 and other information provided by the architecture. Verbose
680 information will be printed at KERN_DEBUG loglevel depending
681 on the mminit_loglevel= command-line option.
686 bool "Debug linked list manipulation"
687 depends on DEBUG_KERNEL
689 Enable this to turn on extended checks in the linked-list
695 bool "Debug SG table operations"
696 depends on DEBUG_KERNEL
698 Enable this to turn on checks on scatter-gather tables. This can
699 help find problems with drivers that do not properly initialize
704 config DEBUG_NOTIFIERS
705 bool "Debug notifier call chains"
706 depends on DEBUG_KERNEL
708 Enable this to turn on sanity checking for notifier call chains.
709 This is most useful for kernel developers to make sure that
710 modules properly unregister themselves from notifier chains.
711 This is a relatively cheap check but if you care about maximum
714 config DEBUG_CREDENTIALS
715 bool "Debug credential management"
716 depends on DEBUG_KERNEL
718 Enable this to turn on some debug checking for credential
719 management. The additional code keeps track of the number of
720 pointers from task_structs to any given cred struct, and checks to
721 see that this number never exceeds the usage count of the cred
724 Furthermore, if SELinux is enabled, this also checks that the
725 security pointer in the cred struct is never seen to be invalid.
730 # Select this config option from the architecture Kconfig, if it
731 # it is preferred to always offer frame pointers as a config
732 # option on the architecture (regardless of KERNEL_DEBUG):
734 config ARCH_WANT_FRAME_POINTERS
739 bool "Compile the kernel with frame pointers"
740 depends on DEBUG_KERNEL && \
741 (CRIS || M68K || M68KNOMMU || FRV || UML || \
742 AVR32 || SUPERH || BLACKFIN || MN10300) || \
743 ARCH_WANT_FRAME_POINTERS
744 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
746 If you say Y here the resulting kernel image will be slightly
747 larger and slower, but it gives very useful debugging information
748 in case of kernel bugs. (precise oopses/stacktraces/warnings)
750 config BOOT_PRINTK_DELAY
751 bool "Delay each boot printk message by N milliseconds"
752 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
754 This build option allows you to read kernel boot messages
755 by inserting a short delay after each one. The delay is
756 specified in milliseconds on the kernel command line,
757 using "boot_delay=N".
759 It is likely that you would also need to use "lpj=M" to preset
760 the "loops per jiffie" value.
761 See a previous boot log for the "lpj" value to use for your
762 system, and then set "lpj=M" before setting "boot_delay=N".
763 NOTE: Using this option may adversely affect SMP systems.
764 I.e., processors other than the first one may not boot up.
765 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
766 what it believes to be lockup conditions.
768 config RCU_TORTURE_TEST
769 tristate "torture tests for RCU"
770 depends on DEBUG_KERNEL
773 This option provides a kernel module that runs torture tests
774 on the RCU infrastructure. The kernel module may be built
775 after the fact on the running kernel to be tested, if desired.
777 Say Y here if you want RCU torture tests to be built into
779 Say M if you want the RCU torture tests to build as a module.
780 Say N if you are unsure.
782 config RCU_TORTURE_TEST_RUNNABLE
783 bool "torture tests for RCU runnable by default"
784 depends on RCU_TORTURE_TEST = y
787 This option provides a way to build the RCU torture tests
788 directly into the kernel without them starting up at boot
789 time. You can use /proc/sys/kernel/rcutorture_runnable
790 to manually override this setting. This /proc file is
791 available only when the RCU torture tests have been built
794 Say Y here if you want the RCU torture tests to start during
795 boot (you probably don't).
796 Say N here if you want the RCU torture tests to start only
797 after being manually enabled via /proc.
799 config RCU_CPU_STALL_DETECTOR
800 bool "Check for stalled CPUs delaying RCU grace periods"
801 depends on TREE_RCU || TREE_PREEMPT_RCU
804 This option causes RCU to printk information on which
805 CPUs are delaying the current grace period, but only when
806 the grace period extends for excessive time periods.
808 Say N if you want to disable such checks.
810 Say Y if you are unsure.
812 config RCU_CPU_STALL_VERBOSE
813 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
814 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
817 This option causes RCU to printk detailed per-task information
818 for any tasks that are stalling the current RCU grace period.
820 Say N if you are unsure.
822 Say Y if you want to enable such checks.
824 config KPROBES_SANITY_TEST
825 bool "Kprobes sanity tests"
826 depends on DEBUG_KERNEL
830 This option provides for testing basic kprobes functionality on
831 boot. A sample kprobe, jprobe and kretprobe are inserted and
832 verified for functionality.
834 Say N if you are unsure.
836 config BACKTRACE_SELF_TEST
837 tristate "Self test for the backtrace code"
838 depends on DEBUG_KERNEL
841 This option provides a kernel module that can be used to test
842 the kernel stack backtrace code. This option is not useful
843 for distributions or general kernels, but only for kernel
844 developers working on architecture code.
846 Note that if you want to also test saved backtraces, you will
847 have to enable STACKTRACE as well.
849 Say N if you are unsure.
851 config DEBUG_BLOCK_EXT_DEVT
852 bool "Force extended block device numbers and spread them"
853 depends on DEBUG_KERNEL
857 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
858 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
859 YOU ARE DOING. Distros, please enable this and fix whatever
862 Conventionally, block device numbers are allocated from
863 predetermined contiguous area. However, extended block area
864 may introduce non-contiguous block device numbers. This
865 option forces most block device numbers to be allocated from
866 the extended space and spreads them to discover kernel or
867 userland code paths which assume predetermined contiguous
868 device number allocation.
870 Note that turning on this debug option shuffles all the
871 device numbers for all IDE and SCSI devices including libata
872 ones, so root partition specified using device number
873 directly (via rdev or root=MAJ:MIN) won't work anymore.
874 Textual device names (root=/dev/sdXn) will continue to work.
876 Say N if you are unsure.
878 config DEBUG_FORCE_WEAK_PER_CPU
879 bool "Force weak per-cpu definitions"
880 depends on DEBUG_KERNEL
882 s390 and alpha require percpu variables in modules to be
883 defined weak to work around addressing range issue which
884 puts the following two restrictions on percpu variable
887 1. percpu symbols must be unique whether static or not
888 2. percpu variables can't be defined inside a function
890 To ensure that generic code follows the above rules, this
891 option forces all percpu variables to be defined as weak.
894 tristate "Linux Kernel Dump Test Tool Module"
899 This module enables testing of the different dumping mechanisms by
900 inducing system failures at predefined crash points.
901 If you don't need it: say N
902 Choose M here to compile this code as a module. The module will be
905 Documentation on how to use the module can be found in
906 Documentation/fault-injection/provoke-crashes.txt
908 config CPU_NOTIFIER_ERROR_INJECT
909 tristate "CPU notifier error injection module"
910 depends on HOTPLUG_CPU && DEBUG_KERNEL
912 This option provides a kernel module that can be used to test
913 the error handling of the cpu notifiers
915 To compile this code as a module, choose M here: the module will
916 be called cpu-notifier-error-inject.
920 config FAULT_INJECTION
921 bool "Fault-injection framework"
922 depends on DEBUG_KERNEL
924 Provide fault-injection framework.
925 For more details, see Documentation/fault-injection/.
928 bool "Fault-injection capability for kmalloc"
929 depends on FAULT_INJECTION
930 depends on SLAB || SLUB
932 Provide fault-injection capability for kmalloc.
934 config FAIL_PAGE_ALLOC
935 bool "Fault-injection capabilitiy for alloc_pages()"
936 depends on FAULT_INJECTION
938 Provide fault-injection capability for alloc_pages().
940 config FAIL_MAKE_REQUEST
941 bool "Fault-injection capability for disk IO"
942 depends on FAULT_INJECTION && BLOCK
944 Provide fault-injection capability for disk IO.
946 config FAIL_IO_TIMEOUT
947 bool "Faul-injection capability for faking disk interrupts"
948 depends on FAULT_INJECTION && BLOCK
950 Provide fault-injection capability on end IO handling. This
951 will make the block layer "forget" an interrupt as configured,
952 thus exercising the error handling.
954 Only works with drivers that use the generic timeout handling,
955 for others it wont do anything.
957 config FAULT_INJECTION_DEBUG_FS
958 bool "Debugfs entries for fault-injection capabilities"
959 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
961 Enable configuration of fault-injection capabilities via debugfs.
963 config FAULT_INJECTION_STACKTRACE_FILTER
964 bool "stacktrace filter for fault-injection capabilities"
965 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
968 select FRAME_POINTER if !PPC && !S390
970 Provide stacktrace filter for fault-injection capabilities
973 bool "Latency measuring infrastructure"
974 select FRAME_POINTER if !MIPS && !PPC && !S390
980 depends on HAVE_LATENCYTOP_SUPPORT
982 Enable this option if you want to use the LatencyTOP tool
983 to find out which userspace is blocking on what kernel operations.
985 config SYSCTL_SYSCALL_CHECK
989 sys_sysctl uses binary paths that have been found challenging
990 to properly maintain and use. This enables checks that help
991 you to keep things correct.
993 source mm/Kconfig.debug
994 source kernel/trace/Kconfig
996 config PROVIDE_OHCI1394_DMA_INIT
997 bool "Remote debugging over FireWire early on boot"
998 depends on PCI && X86
1000 If you want to debug problems which hang or crash the kernel early
1001 on boot and the crashing machine has a FireWire port, you can use
1002 this feature to remotely access the memory of the crashed machine
1003 over FireWire. This employs remote DMA as part of the OHCI1394
1004 specification which is now the standard for FireWire controllers.
1006 With remote DMA, you can monitor the printk buffer remotely using
1007 firescope and access all memory below 4GB using fireproxy from gdb.
1008 Even controlling a kernel debugger is possible using remote DMA.
1012 If ohci1394_dma=early is used as boot parameter, it will initialize
1013 all OHCI1394 controllers which are found in the PCI config space.
1015 As all changes to the FireWire bus such as enabling and disabling
1016 devices cause a bus reset and thereby disable remote DMA for all
1017 devices, be sure to have the cable plugged and FireWire enabled on
1018 the debugging host before booting the debug target for debugging.
1020 This code (~1k) is freed after boot. By then, the firewire stack
1021 in charge of the OHCI-1394 controllers should be used instead.
1023 See Documentation/debugging-via-ohci1394.txt for more information.
1025 config FIREWIRE_OHCI_REMOTE_DMA
1026 bool "Remote debugging over FireWire with firewire-ohci"
1027 depends on FIREWIRE_OHCI
1029 This option lets you use the FireWire bus for remote debugging
1030 with help of the firewire-ohci driver. It enables unfiltered
1031 remote DMA in firewire-ohci.
1032 See Documentation/debugging-via-ohci1394.txt for more information.
1037 bool "Build targets in Documentation/ tree"
1038 depends on HEADERS_CHECK
1040 This option attempts to build objects from the source files in the
1041 kernel Documentation/ tree.
1043 Say N if you are unsure.
1045 config DYNAMIC_DEBUG
1046 bool "Enable dynamic printk() support"
1052 Compiles debug level messages into the kernel, which would not
1053 otherwise be available at runtime. These messages can then be
1054 enabled/disabled based on various levels of scope - per source file,
1055 function, module, format string, and line number. This mechanism
1056 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1057 this compile option is a larger kernel text size of about 2%.
1061 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1062 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1063 filesystem must first be mounted before making use of this feature.
1064 We refer the control file as: <debugfs>/dynamic_debug/control. This
1065 file contains a list of the debug statements that can be enabled. The
1066 format for each line of the file is:
1068 filename:lineno [module]function flags format
1070 filename : source file of the debug statement
1071 lineno : line number of the debug statement
1072 module : module that contains the debug statement
1073 function : function that contains the debug statement
1074 flags : 'p' means the line is turned 'on' for printing
1075 format : the format used for the debug statement
1079 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1080 # filename:lineno [module]function flags format
1081 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1082 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1083 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1087 // enable the message at line 1603 of file svcsock.c
1088 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1089 <debugfs>/dynamic_debug/control
1091 // enable all the messages in file svcsock.c
1092 nullarbor:~ # echo -n 'file svcsock.c +p' >
1093 <debugfs>/dynamic_debug/control
1095 // enable all the messages in the NFS server module
1096 nullarbor:~ # echo -n 'module nfsd +p' >
1097 <debugfs>/dynamic_debug/control
1099 // enable all 12 messages in the function svc_process()
1100 nullarbor:~ # echo -n 'func svc_process +p' >
1101 <debugfs>/dynamic_debug/control
1103 // disable all 12 messages in the function svc_process()
1104 nullarbor:~ # echo -n 'func svc_process -p' >
1105 <debugfs>/dynamic_debug/control
1107 See Documentation/dynamic-debug-howto.txt for additional information.
1109 config DMA_API_DEBUG
1110 bool "Enable debugging of DMA-API usage"
1111 depends on HAVE_DMA_API_DEBUG
1113 Enable this option to debug the use of the DMA API by device drivers.
1114 With this option you will be able to detect common bugs in device
1115 drivers like double-freeing of DMA mappings or freeing mappings that
1116 were never allocated.
1117 This option causes a performance degredation. Use only if you want
1118 to debug device drivers. If unsure, say N.
1120 config ATOMIC64_SELFTEST
1121 bool "Perform an atomic64_t self-test at boot"
1123 Enable this option to test the atomic64_t functions at boot.
1127 source "samples/Kconfig"
1129 source "lib/Kconfig.kgdb"
1131 source "lib/Kconfig.kmemcheck"