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 LOCKUP_DETECTOR
156 bool "Detect Hard and Soft Lockups"
157 depends on DEBUG_KERNEL && !S390
160 Say Y here to enable the kernel to act as a watchdog to detect
161 hard and soft lockups.
163 Softlockups are bugs that cause the kernel to loop in kernel
164 mode for more than 60 seconds, without giving other tasks a
165 chance to run. The current stack trace is displayed upon
166 detection and the system will stay locked up.
168 Hardlockups are bugs that cause the CPU to loop in kernel mode
169 for more than 60 seconds, without letting other interrupts have a
170 chance to run. The current stack trace is displayed upon detection
171 and the system will stay locked up.
173 The overhead should be minimal. A periodic hrtimer runs to
174 generate interrupts and kick the watchdog task every 10-12 seconds.
175 An NMI is generated every 60 seconds or so to check for hardlockups.
177 config HARDLOCKUP_DETECTOR
178 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI
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_ENABLE_DEFAULT
317 int "debug_objects bootup default value (0-1)"
320 depends on DEBUG_OBJECTS
322 Debug objects boot parameter default value
325 bool "Debug slab memory allocations"
326 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
328 Say Y here to have the kernel do limited verification on memory
329 allocation as well as poisoning memory on free to catch use of freed
330 memory. This can make kmalloc/kfree-intensive workloads much slower.
332 config DEBUG_SLAB_LEAK
333 bool "Memory leak debugging"
334 depends on DEBUG_SLAB
337 bool "SLUB debugging on by default"
338 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
341 Boot with debugging on by default. SLUB boots by default with
342 the runtime debug capabilities switched off. Enabling this is
343 equivalent to specifying the "slub_debug" parameter on boot.
344 There is no support for more fine grained debug control like
345 possible with slub_debug=xxx. SLUB debugging may be switched
346 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
351 bool "Enable SLUB performance statistics"
352 depends on SLUB && SLUB_DEBUG && SYSFS
354 SLUB statistics are useful to debug SLUBs allocation behavior in
355 order find ways to optimize the allocator. This should never be
356 enabled for production use since keeping statistics slows down
357 the allocator by a few percentage points. The slabinfo command
358 supports the determination of the most active slabs to figure
359 out which slabs are relevant to a particular load.
360 Try running: slabinfo -DA
362 config DEBUG_KMEMLEAK
363 bool "Kernel memory leak detector"
364 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
365 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE)
367 select DEBUG_FS if SYSFS
368 select STACKTRACE if STACKTRACE_SUPPORT
372 Say Y here if you want to enable the memory leak
373 detector. The memory allocation/freeing is traced in a way
374 similar to the Boehm's conservative garbage collector, the
375 difference being that the orphan objects are not freed but
376 only shown in /sys/kernel/debug/kmemleak. Enabling this
377 feature will introduce an overhead to memory
378 allocations. See Documentation/kmemleak.txt for more
381 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
382 of finding leaks due to the slab objects poisoning.
384 In order to access the kmemleak file, debugfs needs to be
385 mounted (usually at /sys/kernel/debug).
387 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
388 int "Maximum kmemleak early log entries"
389 depends on DEBUG_KMEMLEAK
393 Kmemleak must track all the memory allocations to avoid
394 reporting false positives. Since memory may be allocated or
395 freed before kmemleak is initialised, an early log buffer is
396 used to store these actions. If kmemleak reports "early log
397 buffer exceeded", please increase this value.
399 config DEBUG_KMEMLEAK_TEST
400 tristate "Simple test for the kernel memory leak detector"
401 depends on DEBUG_KMEMLEAK
403 Say Y or M here to build a test for the kernel memory leak
404 detector. This option enables a module that explicitly leaks
410 bool "Debug preemptible kernel"
411 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
414 If you say Y here then the kernel will use a debug variant of the
415 commonly used smp_processor_id() function and will print warnings
416 if kernel code uses it in a preemption-unsafe way. Also, the kernel
417 will detect preemption count underflows.
419 config DEBUG_RT_MUTEXES
420 bool "RT Mutex debugging, deadlock detection"
421 depends on DEBUG_KERNEL && RT_MUTEXES
423 This allows rt mutex semantics violations and rt mutex related
424 deadlocks (lockups) to be detected and reported automatically.
429 depends on DEBUG_RT_MUTEXES
431 config RT_MUTEX_TESTER
432 bool "Built-in scriptable tester for rt-mutexes"
433 depends on DEBUG_KERNEL && RT_MUTEXES
435 This option enables a rt-mutex tester.
437 config DEBUG_SPINLOCK
438 bool "Spinlock and rw-lock debugging: basic checks"
439 depends on DEBUG_KERNEL
441 Say Y here and build SMP to catch missing spinlock initialization
442 and certain other kinds of spinlock errors commonly made. This is
443 best used in conjunction with the NMI watchdog so that spinlock
444 deadlocks are also debuggable.
447 bool "Mutex debugging: basic checks"
448 depends on DEBUG_KERNEL
450 This feature allows mutex semantics violations to be detected and
453 config DEBUG_LOCK_ALLOC
454 bool "Lock debugging: detect incorrect freeing of live locks"
455 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
456 select DEBUG_SPINLOCK
460 This feature will check whether any held lock (spinlock, rwlock,
461 mutex or rwsem) is incorrectly freed by the kernel, via any of the
462 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
463 vfree(), etc.), whether a live lock is incorrectly reinitialized via
464 spin_lock_init()/mutex_init()/etc., or whether there is any lock
465 held during task exit.
468 bool "Lock debugging: prove locking correctness"
469 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
471 select DEBUG_SPINLOCK
473 select DEBUG_LOCK_ALLOC
476 This feature enables the kernel to prove that all locking
477 that occurs in the kernel runtime is mathematically
478 correct: that under no circumstance could an arbitrary (and
479 not yet triggered) combination of observed locking
480 sequences (on an arbitrary number of CPUs, running an
481 arbitrary number of tasks and interrupt contexts) cause a
484 In short, this feature enables the kernel to report locking
485 related deadlocks before they actually occur.
487 The proof does not depend on how hard and complex a
488 deadlock scenario would be to trigger: how many
489 participant CPUs, tasks and irq-contexts would be needed
490 for it to trigger. The proof also does not depend on
491 timing: if a race and a resulting deadlock is possible
492 theoretically (no matter how unlikely the race scenario
493 is), it will be proven so and will immediately be
494 reported by the kernel (once the event is observed that
495 makes the deadlock theoretically possible).
497 If a deadlock is impossible (i.e. the locking rules, as
498 observed by the kernel, are mathematically correct), the
499 kernel reports nothing.
501 NOTE: this feature can also be enabled for rwlocks, mutexes
502 and rwsems - in which case all dependencies between these
503 different locking variants are observed and mapped too, and
504 the proof of observed correctness is also maintained for an
505 arbitrary combination of these separate locking variants.
507 For more details, see Documentation/lockdep-design.txt.
510 bool "RCU debugging: prove RCU correctness"
511 depends on PROVE_LOCKING
514 This feature enables lockdep extensions that check for correct
515 use of RCU APIs. This is currently under development. Say Y
516 if you want to debug RCU usage or help work on the PROVE_RCU
519 Say N if you are unsure.
523 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
525 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
530 bool "Lock usage statistics"
531 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
533 select DEBUG_SPINLOCK
535 select DEBUG_LOCK_ALLOC
538 This feature enables tracking lock contention points
540 For more details, see Documentation/lockstat.txt
542 This also enables lock events required by "perf lock",
544 If you want to use "perf lock", you also need to turn on
545 CONFIG_EVENT_TRACING.
547 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
548 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
551 bool "Lock dependency engine debugging"
552 depends on DEBUG_KERNEL && LOCKDEP
554 If you say Y here, the lock dependency engine will do
555 additional runtime checks to debug itself, at the price
556 of more runtime overhead.
558 config TRACE_IRQFLAGS
559 depends on DEBUG_KERNEL
562 depends on TRACE_IRQFLAGS_SUPPORT
563 depends on PROVE_LOCKING
565 config DEBUG_SPINLOCK_SLEEP
566 bool "Spinlock debugging: sleep-inside-spinlock checking"
567 depends on DEBUG_KERNEL
569 If you say Y here, various routines which may sleep will become very
570 noisy if they are called with a spinlock held.
572 config DEBUG_LOCKING_API_SELFTESTS
573 bool "Locking API boot-time self-tests"
574 depends on DEBUG_KERNEL
576 Say Y here if you want the kernel to run a short self-test during
577 bootup. The self-test checks whether common types of locking bugs
578 are detected by debugging mechanisms or not. (if you disable
579 lock debugging then those bugs wont be detected of course.)
580 The following locking APIs are covered: spinlocks, rwlocks,
585 depends on STACKTRACE_SUPPORT
588 bool "kobject debugging"
589 depends on DEBUG_KERNEL
591 If you say Y here, some extra kobject debugging messages will be sent
595 bool "Highmem debugging"
596 depends on DEBUG_KERNEL && HIGHMEM
598 This options enables addition error checking for high memory systems.
599 Disable for production systems.
601 config DEBUG_BUGVERBOSE
602 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
604 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
605 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
608 Say Y here to make BUG() panics output the file name and line number
609 of the BUG call as well as the EIP and oops trace. This aids
610 debugging but costs about 70-100K of memory.
613 bool "Compile the kernel with debug info"
614 depends on DEBUG_KERNEL
616 If you say Y here the resulting kernel image will include
617 debugging info resulting in a larger kernel image.
618 This adds debug symbols to the kernel and modules (gcc -g), and
619 is needed if you intend to use kernel crashdump or binary object
620 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
621 Say Y here only if you plan to debug the kernel.
627 depends on DEBUG_KERNEL
629 Enable this to turn on extended checks in the virtual-memory system
630 that may impact performance.
635 bool "Debug VM translations"
636 depends on DEBUG_KERNEL && X86
638 Enable some costly sanity checks in virtual to page code. This can
639 catch mistakes with virt_to_page() and friends.
643 config DEBUG_NOMMU_REGIONS
644 bool "Debug the global anon/private NOMMU mapping region tree"
645 depends on DEBUG_KERNEL && !MMU
647 This option causes the global tree of anonymous and private mapping
648 regions to be regularly checked for invalid topology.
650 config DEBUG_WRITECOUNT
651 bool "Debug filesystem writers count"
652 depends on DEBUG_KERNEL
654 Enable this to catch wrong use of the writers count in struct
655 vfsmount. This will increase the size of each file struct by
660 config DEBUG_MEMORY_INIT
661 bool "Debug memory initialisation" if EMBEDDED
664 Enable this for additional checks during memory initialisation.
665 The sanity checks verify aspects of the VM such as the memory model
666 and other information provided by the architecture. Verbose
667 information will be printed at KERN_DEBUG loglevel depending
668 on the mminit_loglevel= command-line option.
673 bool "Debug linked list manipulation"
674 depends on DEBUG_KERNEL
676 Enable this to turn on extended checks in the linked-list
682 bool "Debug SG table operations"
683 depends on DEBUG_KERNEL
685 Enable this to turn on checks on scatter-gather tables. This can
686 help find problems with drivers that do not properly initialize
691 config DEBUG_NOTIFIERS
692 bool "Debug notifier call chains"
693 depends on DEBUG_KERNEL
695 Enable this to turn on sanity checking for notifier call chains.
696 This is most useful for kernel developers to make sure that
697 modules properly unregister themselves from notifier chains.
698 This is a relatively cheap check but if you care about maximum
701 config DEBUG_CREDENTIALS
702 bool "Debug credential management"
703 depends on DEBUG_KERNEL
705 Enable this to turn on some debug checking for credential
706 management. The additional code keeps track of the number of
707 pointers from task_structs to any given cred struct, and checks to
708 see that this number never exceeds the usage count of the cred
711 Furthermore, if SELinux is enabled, this also checks that the
712 security pointer in the cred struct is never seen to be invalid.
717 # Select this config option from the architecture Kconfig, if it
718 # it is preferred to always offer frame pointers as a config
719 # option on the architecture (regardless of KERNEL_DEBUG):
721 config ARCH_WANT_FRAME_POINTERS
726 bool "Compile the kernel with frame pointers"
727 depends on DEBUG_KERNEL && \
728 (CRIS || M68K || M68KNOMMU || FRV || UML || \
729 AVR32 || SUPERH || BLACKFIN || MN10300) || \
730 ARCH_WANT_FRAME_POINTERS
731 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
733 If you say Y here the resulting kernel image will be slightly
734 larger and slower, but it gives very useful debugging information
735 in case of kernel bugs. (precise oopses/stacktraces/warnings)
737 config BOOT_PRINTK_DELAY
738 bool "Delay each boot printk message by N milliseconds"
739 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
741 This build option allows you to read kernel boot messages
742 by inserting a short delay after each one. The delay is
743 specified in milliseconds on the kernel command line,
744 using "boot_delay=N".
746 It is likely that you would also need to use "lpj=M" to preset
747 the "loops per jiffie" value.
748 See a previous boot log for the "lpj" value to use for your
749 system, and then set "lpj=M" before setting "boot_delay=N".
750 NOTE: Using this option may adversely affect SMP systems.
751 I.e., processors other than the first one may not boot up.
752 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
753 what it believes to be lockup conditions.
755 config RCU_TORTURE_TEST
756 tristate "torture tests for RCU"
757 depends on DEBUG_KERNEL
760 This option provides a kernel module that runs torture tests
761 on the RCU infrastructure. The kernel module may be built
762 after the fact on the running kernel to be tested, if desired.
764 Say Y here if you want RCU torture tests to be built into
766 Say M if you want the RCU torture tests to build as a module.
767 Say N if you are unsure.
769 config RCU_TORTURE_TEST_RUNNABLE
770 bool "torture tests for RCU runnable by default"
771 depends on RCU_TORTURE_TEST = y
774 This option provides a way to build the RCU torture tests
775 directly into the kernel without them starting up at boot
776 time. You can use /proc/sys/kernel/rcutorture_runnable
777 to manually override this setting. This /proc file is
778 available only when the RCU torture tests have been built
781 Say Y here if you want the RCU torture tests to start during
782 boot (you probably don't).
783 Say N here if you want the RCU torture tests to start only
784 after being manually enabled via /proc.
786 config RCU_CPU_STALL_DETECTOR
787 bool "Check for stalled CPUs delaying RCU grace periods"
788 depends on TREE_RCU || TREE_PREEMPT_RCU
791 This option causes RCU to printk information on which
792 CPUs are delaying the current grace period, but only when
793 the grace period extends for excessive time periods.
795 Say N if you want to disable such checks.
797 Say Y if you are unsure.
799 config RCU_CPU_STALL_VERBOSE
800 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
801 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
804 This option causes RCU to printk detailed per-task information
805 for any tasks that are stalling the current RCU grace period.
807 Say N if you are unsure.
809 Say Y if you want to enable such checks.
811 config KPROBES_SANITY_TEST
812 bool "Kprobes sanity tests"
813 depends on DEBUG_KERNEL
817 This option provides for testing basic kprobes functionality on
818 boot. A sample kprobe, jprobe and kretprobe are inserted and
819 verified for functionality.
821 Say N if you are unsure.
823 config BACKTRACE_SELF_TEST
824 tristate "Self test for the backtrace code"
825 depends on DEBUG_KERNEL
828 This option provides a kernel module that can be used to test
829 the kernel stack backtrace code. This option is not useful
830 for distributions or general kernels, but only for kernel
831 developers working on architecture code.
833 Note that if you want to also test saved backtraces, you will
834 have to enable STACKTRACE as well.
836 Say N if you are unsure.
838 config DEBUG_BLOCK_EXT_DEVT
839 bool "Force extended block device numbers and spread them"
840 depends on DEBUG_KERNEL
844 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
845 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
846 YOU ARE DOING. Distros, please enable this and fix whatever
849 Conventionally, block device numbers are allocated from
850 predetermined contiguous area. However, extended block area
851 may introduce non-contiguous block device numbers. This
852 option forces most block device numbers to be allocated from
853 the extended space and spreads them to discover kernel or
854 userland code paths which assume predetermined contiguous
855 device number allocation.
857 Note that turning on this debug option shuffles all the
858 device numbers for all IDE and SCSI devices including libata
859 ones, so root partition specified using device number
860 directly (via rdev or root=MAJ:MIN) won't work anymore.
861 Textual device names (root=/dev/sdXn) will continue to work.
863 Say N if you are unsure.
865 config DEBUG_FORCE_WEAK_PER_CPU
866 bool "Force weak per-cpu definitions"
867 depends on DEBUG_KERNEL
869 s390 and alpha require percpu variables in modules to be
870 defined weak to work around addressing range issue which
871 puts the following two restrictions on percpu variable
874 1. percpu symbols must be unique whether static or not
875 2. percpu variables can't be defined inside a function
877 To ensure that generic code follows the above rules, this
878 option forces all percpu variables to be defined as weak.
881 tristate "Linux Kernel Dump Test Tool Module"
886 This module enables testing of the different dumping mechanisms by
887 inducing system failures at predefined crash points.
888 If you don't need it: say N
889 Choose M here to compile this code as a module. The module will be
892 Documentation on how to use the module can be found in
893 Documentation/fault-injection/provoke-crashes.txt
895 config FAULT_INJECTION
896 bool "Fault-injection framework"
897 depends on DEBUG_KERNEL
899 Provide fault-injection framework.
900 For more details, see Documentation/fault-injection/.
903 bool "Fault-injection capability for kmalloc"
904 depends on FAULT_INJECTION
905 depends on SLAB || SLUB
907 Provide fault-injection capability for kmalloc.
909 config FAIL_PAGE_ALLOC
910 bool "Fault-injection capabilitiy for alloc_pages()"
911 depends on FAULT_INJECTION
913 Provide fault-injection capability for alloc_pages().
915 config FAIL_MAKE_REQUEST
916 bool "Fault-injection capability for disk IO"
917 depends on FAULT_INJECTION && BLOCK
919 Provide fault-injection capability for disk IO.
921 config FAIL_IO_TIMEOUT
922 bool "Faul-injection capability for faking disk interrupts"
923 depends on FAULT_INJECTION && BLOCK
925 Provide fault-injection capability on end IO handling. This
926 will make the block layer "forget" an interrupt as configured,
927 thus exercising the error handling.
929 Only works with drivers that use the generic timeout handling,
930 for others it wont do anything.
932 config FAULT_INJECTION_DEBUG_FS
933 bool "Debugfs entries for fault-injection capabilities"
934 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
936 Enable configuration of fault-injection capabilities via debugfs.
938 config FAULT_INJECTION_STACKTRACE_FILTER
939 bool "stacktrace filter for fault-injection capabilities"
940 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
943 select FRAME_POINTER if !PPC && !S390
945 Provide stacktrace filter for fault-injection capabilities
948 bool "Latency measuring infrastructure"
949 select FRAME_POINTER if !MIPS && !PPC && !S390
955 depends on HAVE_LATENCYTOP_SUPPORT
957 Enable this option if you want to use the LatencyTOP tool
958 to find out which userspace is blocking on what kernel operations.
960 config SYSCTL_SYSCALL_CHECK
964 sys_sysctl uses binary paths that have been found challenging
965 to properly maintain and use. This enables checks that help
966 you to keep things correct.
968 source mm/Kconfig.debug
969 source kernel/trace/Kconfig
971 config PROVIDE_OHCI1394_DMA_INIT
972 bool "Remote debugging over FireWire early on boot"
973 depends on PCI && X86
975 If you want to debug problems which hang or crash the kernel early
976 on boot and the crashing machine has a FireWire port, you can use
977 this feature to remotely access the memory of the crashed machine
978 over FireWire. This employs remote DMA as part of the OHCI1394
979 specification which is now the standard for FireWire controllers.
981 With remote DMA, you can monitor the printk buffer remotely using
982 firescope and access all memory below 4GB using fireproxy from gdb.
983 Even controlling a kernel debugger is possible using remote DMA.
987 If ohci1394_dma=early is used as boot parameter, it will initialize
988 all OHCI1394 controllers which are found in the PCI config space.
990 As all changes to the FireWire bus such as enabling and disabling
991 devices cause a bus reset and thereby disable remote DMA for all
992 devices, be sure to have the cable plugged and FireWire enabled on
993 the debugging host before booting the debug target for debugging.
995 This code (~1k) is freed after boot. By then, the firewire stack
996 in charge of the OHCI-1394 controllers should be used instead.
998 See Documentation/debugging-via-ohci1394.txt for more information.
1000 config FIREWIRE_OHCI_REMOTE_DMA
1001 bool "Remote debugging over FireWire with firewire-ohci"
1002 depends on FIREWIRE_OHCI
1004 This option lets you use the FireWire bus for remote debugging
1005 with help of the firewire-ohci driver. It enables unfiltered
1006 remote DMA in firewire-ohci.
1007 See Documentation/debugging-via-ohci1394.txt for more information.
1012 bool "Build targets in Documentation/ tree"
1013 depends on HEADERS_CHECK
1015 This option attempts to build objects from the source files in the
1016 kernel Documentation/ tree.
1018 Say N if you are unsure.
1020 config DYNAMIC_DEBUG
1021 bool "Enable dynamic printk() support"
1027 Compiles debug level messages into the kernel, which would not
1028 otherwise be available at runtime. These messages can then be
1029 enabled/disabled based on various levels of scope - per source file,
1030 function, module, format string, and line number. This mechanism
1031 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1032 this compile option is a larger kernel text size of about 2%.
1036 Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
1037 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1038 filesystem must first be mounted before making use of this feature.
1039 We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
1040 file contains a list of the debug statements that can be enabled. The
1041 format for each line of the file is:
1043 filename:lineno [module]function flags format
1045 filename : source file of the debug statement
1046 lineno : line number of the debug statement
1047 module : module that contains the debug statement
1048 function : function that contains the debug statement
1049 flags : 'p' means the line is turned 'on' for printing
1050 format : the format used for the debug statement
1054 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
1055 # filename:lineno [module]function flags format
1056 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1057 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1058 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1062 // enable the message at line 1603 of file svcsock.c
1063 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1064 <debugfs>/dynamic_debug/ddebug
1066 // enable all the messages in file svcsock.c
1067 nullarbor:~ # echo -n 'file svcsock.c +p' >
1068 <debugfs>/dynamic_debug/ddebug
1070 // enable all the messages in the NFS server module
1071 nullarbor:~ # echo -n 'module nfsd +p' >
1072 <debugfs>/dynamic_debug/ddebug
1074 // enable all 12 messages in the function svc_process()
1075 nullarbor:~ # echo -n 'func svc_process +p' >
1076 <debugfs>/dynamic_debug/ddebug
1078 // disable all 12 messages in the function svc_process()
1079 nullarbor:~ # echo -n 'func svc_process -p' >
1080 <debugfs>/dynamic_debug/ddebug
1082 See Documentation/dynamic-debug-howto.txt for additional information.
1084 config DMA_API_DEBUG
1085 bool "Enable debugging of DMA-API usage"
1086 depends on HAVE_DMA_API_DEBUG
1088 Enable this option to debug the use of the DMA API by device drivers.
1089 With this option you will be able to detect common bugs in device
1090 drivers like double-freeing of DMA mappings or freeing mappings that
1091 were never allocated.
1092 This option causes a performance degredation. Use only if you want
1093 to debug device drivers. If unsure, say N.
1095 source "samples/Kconfig"
1097 source "lib/Kconfig.kgdb"
1099 source "lib/Kconfig.kmemcheck"