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"
80 debugfs is a virtual file system that kernel developers use to put
81 debugging files into. Enable this option to be able to read and
84 For detailed documentation on the debugfs API, see
85 Documentation/DocBook/filesystems.
90 bool "Run 'make headers_check' when building vmlinux"
93 This option will extract the user-visible kernel headers whenever
94 building the kernel, and will run basic sanity checks on them to
95 ensure that exported files do not attempt to include files which
96 were not exported, etc.
98 If you're making modifications to header files which are
99 relevant for userspace, say 'Y', and check the headers
100 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
101 your build tree), to make sure they're suitable.
103 config DEBUG_SECTION_MISMATCH
104 bool "Enable full Section mismatch analysis"
105 depends on UNDEFINED || (BLACKFIN)
107 # This option is on purpose disabled for now.
108 # It will be enabled when we are down to a reasonable number
109 # of section mismatch warnings (< 10 for an allyesconfig build)
111 The section mismatch analysis checks if there are illegal
112 references from one section to another section.
113 Linux will during link or during runtime drop some sections
114 and any use of code/data previously in these sections will
115 most likely result in an oops.
116 In the code functions and variables are annotated with
117 __init, __devinit etc. (see full list in include/linux/init.h)
118 which results in the code/data being placed in specific sections.
119 The section mismatch analysis is always done after a full
120 kernel build but enabling this option will in addition
122 - Add the option -fno-inline-functions-called-once to gcc
123 When inlining a function annotated __init in a non-init
124 function we would lose the section information and thus
125 the analysis would not catch the illegal reference.
126 This option tells gcc to inline less but will also
127 result in a larger kernel.
128 - Run the section mismatch analysis for each module/built-in.o
129 When we run the section mismatch analysis on vmlinux.o we
130 lose valueble information about where the mismatch was
132 Running the analysis for each module/built-in.o file
133 will tell where the mismatch happens much closer to the
134 source. The drawback is that we will report the same
135 mismatch at least twice.
136 - Enable verbose reporting from modpost to help solving
137 the section mismatches reported.
140 bool "Kernel debugging"
142 Say Y here if you are developing drivers or trying to debug and
143 identify kernel problems.
146 bool "Debug shared IRQ handlers"
147 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
149 Enable this to generate a spurious interrupt as soon as a shared
150 interrupt handler is registered, and just before one is deregistered.
151 Drivers ought to be able to handle interrupts coming in at those
152 points; some don't and need to be caught.
154 config LOCKUP_DETECTOR
155 bool "Detect Hard and Soft Lockups"
156 depends on DEBUG_KERNEL && !S390
158 Say Y here to enable the kernel to act as a watchdog to detect
159 hard and soft lockups.
161 Softlockups are bugs that cause the kernel to loop in kernel
162 mode for more than 60 seconds, without giving other tasks a
163 chance to run. The current stack trace is displayed upon
164 detection and the system will stay locked up.
166 Hardlockups are bugs that cause the CPU to loop in kernel mode
167 for more than 60 seconds, without letting other interrupts have a
168 chance to run. The current stack trace is displayed upon detection
169 and the system will stay locked up.
171 The overhead should be minimal. A periodic hrtimer runs to
172 generate interrupts and kick the watchdog task every 10-12 seconds.
173 An NMI is generated every 60 seconds or so to check for hardlockups.
175 config HARDLOCKUP_DETECTOR
176 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI
178 config BOOTPARAM_SOFTLOCKUP_PANIC
179 bool "Panic (Reboot) On Soft Lockups"
180 depends on LOCKUP_DETECTOR
182 Say Y here to enable the kernel to panic on "soft lockups",
183 which are bugs that cause the kernel to loop in kernel
184 mode for more than 60 seconds, without giving other tasks a
187 The panic can be used in combination with panic_timeout,
188 to cause the system to reboot automatically after a
189 lockup has been detected. This feature is useful for
190 high-availability systems that have uptime guarantees and
191 where a lockup must be resolved ASAP.
195 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
197 depends on LOCKUP_DETECTOR
199 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
200 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
202 config DETECT_HUNG_TASK
203 bool "Detect Hung Tasks"
204 depends on DEBUG_KERNEL
205 default DETECT_SOFTLOCKUP
207 Say Y here to enable the kernel to detect "hung tasks",
208 which are bugs that cause the task to be stuck in
209 uninterruptible "D" state indefinitiley.
211 When a hung task is detected, the kernel will print the
212 current stack trace (which you should report), but the
213 task will stay in uninterruptible state. If lockdep is
214 enabled then all held locks will also be reported. This
215 feature has negligible overhead.
217 config BOOTPARAM_HUNG_TASK_PANIC
218 bool "Panic (Reboot) On Hung Tasks"
219 depends on DETECT_HUNG_TASK
221 Say Y here to enable the kernel to panic on "hung tasks",
222 which are bugs that cause the kernel to leave a task stuck
223 in uninterruptible "D" state.
225 The panic can be used in combination with panic_timeout,
226 to cause the system to reboot automatically after a
227 hung task has been detected. This feature is useful for
228 high-availability systems that have uptime guarantees and
229 where a hung tasks must be resolved ASAP.
233 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
235 depends on DETECT_HUNG_TASK
237 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
238 default 1 if BOOTPARAM_HUNG_TASK_PANIC
241 bool "Collect scheduler debugging info"
242 depends on DEBUG_KERNEL && PROC_FS
245 If you say Y here, the /proc/sched_debug file will be provided
246 that can help debug the scheduler. The runtime overhead of this
250 bool "Collect scheduler statistics"
251 depends on DEBUG_KERNEL && PROC_FS
253 If you say Y here, additional code will be inserted into the
254 scheduler and related routines to collect statistics about
255 scheduler behavior and provide them in /proc/schedstat. These
256 stats may be useful for both tuning and debugging the scheduler
257 If you aren't debugging the scheduler or trying to tune a specific
258 application, you can say N to avoid the very slight overhead
262 bool "Collect kernel timers statistics"
263 depends on DEBUG_KERNEL && PROC_FS
265 If you say Y here, additional code will be inserted into the
266 timer routines to collect statistics about kernel timers being
267 reprogrammed. The statistics can be read from /proc/timer_stats.
268 The statistics collection is started by writing 1 to /proc/timer_stats,
269 writing 0 stops it. This feature is useful to collect information
270 about timer usage patterns in kernel and userspace. This feature
271 is lightweight if enabled in the kernel config but not activated
272 (it defaults to deactivated on bootup and will only be activated
273 if some application like powertop activates it explicitly).
276 bool "Debug object operations"
277 depends on DEBUG_KERNEL
279 If you say Y here, additional code will be inserted into the
280 kernel to track the life time of various objects and validate
281 the operations on those objects.
283 config DEBUG_OBJECTS_SELFTEST
284 bool "Debug objects selftest"
285 depends on DEBUG_OBJECTS
287 This enables the selftest of the object debug code.
289 config DEBUG_OBJECTS_FREE
290 bool "Debug objects in freed memory"
291 depends on DEBUG_OBJECTS
293 This enables checks whether a k/v free operation frees an area
294 which contains an object which has not been deactivated
295 properly. This can make kmalloc/kfree-intensive workloads
298 config DEBUG_OBJECTS_TIMERS
299 bool "Debug timer objects"
300 depends on DEBUG_OBJECTS
302 If you say Y here, additional code will be inserted into the
303 timer routines to track the life time of timer objects and
304 validate the timer operations.
306 config DEBUG_OBJECTS_WORK
307 bool "Debug work objects"
308 depends on DEBUG_OBJECTS
310 If you say Y here, additional code will be inserted into the
311 work queue routines to track the life time of work objects and
312 validate the work operations.
314 config DEBUG_OBJECTS_RCU_HEAD
315 bool "Debug RCU callbacks objects"
316 depends on DEBUG_OBJECTS && PREEMPT
318 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
320 config DEBUG_OBJECTS_ENABLE_DEFAULT
321 int "debug_objects bootup default value (0-1)"
324 depends on DEBUG_OBJECTS
326 Debug objects boot parameter default value
329 bool "Debug slab memory allocations"
330 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
332 Say Y here to have the kernel do limited verification on memory
333 allocation as well as poisoning memory on free to catch use of freed
334 memory. This can make kmalloc/kfree-intensive workloads much slower.
336 config DEBUG_SLAB_LEAK
337 bool "Memory leak debugging"
338 depends on DEBUG_SLAB
341 bool "SLUB debugging on by default"
342 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
345 Boot with debugging on by default. SLUB boots by default with
346 the runtime debug capabilities switched off. Enabling this is
347 equivalent to specifying the "slub_debug" parameter on boot.
348 There is no support for more fine grained debug control like
349 possible with slub_debug=xxx. SLUB debugging may be switched
350 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
355 bool "Enable SLUB performance statistics"
356 depends on SLUB && SLUB_DEBUG && SYSFS
358 SLUB statistics are useful to debug SLUBs allocation behavior in
359 order find ways to optimize the allocator. This should never be
360 enabled for production use since keeping statistics slows down
361 the allocator by a few percentage points. The slabinfo command
362 supports the determination of the most active slabs to figure
363 out which slabs are relevant to a particular load.
364 Try running: slabinfo -DA
366 config DEBUG_KMEMLEAK
367 bool "Kernel memory leak detector"
368 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
369 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE)
371 select DEBUG_FS if SYSFS
372 select STACKTRACE if STACKTRACE_SUPPORT
376 Say Y here if you want to enable the memory leak
377 detector. The memory allocation/freeing is traced in a way
378 similar to the Boehm's conservative garbage collector, the
379 difference being that the orphan objects are not freed but
380 only shown in /sys/kernel/debug/kmemleak. Enabling this
381 feature will introduce an overhead to memory
382 allocations. See Documentation/kmemleak.txt for more
385 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
386 of finding leaks due to the slab objects poisoning.
388 In order to access the kmemleak file, debugfs needs to be
389 mounted (usually at /sys/kernel/debug).
391 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
392 int "Maximum kmemleak early log entries"
393 depends on DEBUG_KMEMLEAK
397 Kmemleak must track all the memory allocations to avoid
398 reporting false positives. Since memory may be allocated or
399 freed before kmemleak is initialised, an early log buffer is
400 used to store these actions. If kmemleak reports "early log
401 buffer exceeded", please increase this value.
403 config DEBUG_KMEMLEAK_TEST
404 tristate "Simple test for the kernel memory leak detector"
405 depends on DEBUG_KMEMLEAK
407 Say Y or M here to build a test for the kernel memory leak
408 detector. This option enables a module that explicitly leaks
413 config DEBUG_KMEMLEAK_DEFAULT_OFF
414 bool "Default kmemleak to off"
415 depends on DEBUG_KMEMLEAK
417 Say Y here to disable kmemleak by default. It can then be enabled
418 on the command line via kmemleak=on.
421 bool "Debug preemptible kernel"
422 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
425 If you say Y here then the kernel will use a debug variant of the
426 commonly used smp_processor_id() function and will print warnings
427 if kernel code uses it in a preemption-unsafe way. Also, the kernel
428 will detect preemption count underflows.
430 config DEBUG_RT_MUTEXES
431 bool "RT Mutex debugging, deadlock detection"
432 depends on DEBUG_KERNEL && RT_MUTEXES
434 This allows rt mutex semantics violations and rt mutex related
435 deadlocks (lockups) to be detected and reported automatically.
440 depends on DEBUG_RT_MUTEXES
442 config RT_MUTEX_TESTER
443 bool "Built-in scriptable tester for rt-mutexes"
444 depends on DEBUG_KERNEL && RT_MUTEXES
446 This option enables a rt-mutex tester.
448 config DEBUG_SPINLOCK
449 bool "Spinlock and rw-lock debugging: basic checks"
450 depends on DEBUG_KERNEL
452 Say Y here and build SMP to catch missing spinlock initialization
453 and certain other kinds of spinlock errors commonly made. This is
454 best used in conjunction with the NMI watchdog so that spinlock
455 deadlocks are also debuggable.
458 bool "Mutex debugging: basic checks"
459 depends on DEBUG_KERNEL
461 This feature allows mutex semantics violations to be detected and
464 config DEBUG_LOCK_ALLOC
465 bool "Lock debugging: detect incorrect freeing of live locks"
466 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
467 select DEBUG_SPINLOCK
471 This feature will check whether any held lock (spinlock, rwlock,
472 mutex or rwsem) is incorrectly freed by the kernel, via any of the
473 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
474 vfree(), etc.), whether a live lock is incorrectly reinitialized via
475 spin_lock_init()/mutex_init()/etc., or whether there is any lock
476 held during task exit.
479 bool "Lock debugging: prove locking correctness"
480 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
482 select DEBUG_SPINLOCK
484 select DEBUG_LOCK_ALLOC
487 This feature enables the kernel to prove that all locking
488 that occurs in the kernel runtime is mathematically
489 correct: that under no circumstance could an arbitrary (and
490 not yet triggered) combination of observed locking
491 sequences (on an arbitrary number of CPUs, running an
492 arbitrary number of tasks and interrupt contexts) cause a
495 In short, this feature enables the kernel to report locking
496 related deadlocks before they actually occur.
498 The proof does not depend on how hard and complex a
499 deadlock scenario would be to trigger: how many
500 participant CPUs, tasks and irq-contexts would be needed
501 for it to trigger. The proof also does not depend on
502 timing: if a race and a resulting deadlock is possible
503 theoretically (no matter how unlikely the race scenario
504 is), it will be proven so and will immediately be
505 reported by the kernel (once the event is observed that
506 makes the deadlock theoretically possible).
508 If a deadlock is impossible (i.e. the locking rules, as
509 observed by the kernel, are mathematically correct), the
510 kernel reports nothing.
512 NOTE: this feature can also be enabled for rwlocks, mutexes
513 and rwsems - in which case all dependencies between these
514 different locking variants are observed and mapped too, and
515 the proof of observed correctness is also maintained for an
516 arbitrary combination of these separate locking variants.
518 For more details, see Documentation/lockdep-design.txt.
521 bool "RCU debugging: prove RCU correctness"
522 depends on PROVE_LOCKING
525 This feature enables lockdep extensions that check for correct
526 use of RCU APIs. This is currently under development. Say Y
527 if you want to debug RCU usage or help work on the PROVE_RCU
530 Say N if you are unsure.
532 config PROVE_RCU_REPEATEDLY
533 bool "RCU debugging: don't disable PROVE_RCU on first splat"
537 By itself, PROVE_RCU will disable checking upon issuing the
538 first warning (or "splat"). This feature prevents such
539 disabling, allowing multiple RCU-lockdep warnings to be printed
542 Say N if you are unsure.
546 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
548 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
553 bool "Lock usage statistics"
554 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
556 select DEBUG_SPINLOCK
558 select DEBUG_LOCK_ALLOC
561 This feature enables tracking lock contention points
563 For more details, see Documentation/lockstat.txt
565 This also enables lock events required by "perf lock",
567 If you want to use "perf lock", you also need to turn on
568 CONFIG_EVENT_TRACING.
570 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
571 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
574 bool "Lock dependency engine debugging"
575 depends on DEBUG_KERNEL && LOCKDEP
577 If you say Y here, the lock dependency engine will do
578 additional runtime checks to debug itself, at the price
579 of more runtime overhead.
581 config TRACE_IRQFLAGS
582 depends on DEBUG_KERNEL
585 depends on TRACE_IRQFLAGS_SUPPORT
586 depends on PROVE_LOCKING
588 config DEBUG_SPINLOCK_SLEEP
589 bool "Spinlock debugging: sleep-inside-spinlock checking"
590 depends on DEBUG_KERNEL
592 If you say Y here, various routines which may sleep will become very
593 noisy if they are called with a spinlock held.
595 config DEBUG_LOCKING_API_SELFTESTS
596 bool "Locking API boot-time self-tests"
597 depends on DEBUG_KERNEL
599 Say Y here if you want the kernel to run a short self-test during
600 bootup. The self-test checks whether common types of locking bugs
601 are detected by debugging mechanisms or not. (if you disable
602 lock debugging then those bugs wont be detected of course.)
603 The following locking APIs are covered: spinlocks, rwlocks,
608 depends on STACKTRACE_SUPPORT
612 bool "kobject debugging"
613 depends on DEBUG_KERNEL
615 If you say Y here, some extra kobject debugging messages will be sent
619 bool "Highmem debugging"
620 depends on DEBUG_KERNEL && HIGHMEM
622 This options enables addition error checking for high memory systems.
623 Disable for production systems.
625 config DEBUG_BUGVERBOSE
626 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
628 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
629 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
632 Say Y here to make BUG() panics output the file name and line number
633 of the BUG call as well as the EIP and oops trace. This aids
634 debugging but costs about 70-100K of memory.
637 bool "Compile the kernel with debug info"
638 depends on DEBUG_KERNEL
640 If you say Y here the resulting kernel image will include
641 debugging info resulting in a larger kernel image.
642 This adds debug symbols to the kernel and modules (gcc -g), and
643 is needed if you intend to use kernel crashdump or binary object
644 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
645 Say Y here only if you plan to debug the kernel.
649 config DEBUG_INFO_REDUCED
650 bool "Reduce debugging information"
651 depends on DEBUG_INFO
653 If you say Y here gcc is instructed to generate less debugging
654 information for structure types. This means that tools that
655 need full debugging information (like kgdb or systemtap) won't
656 be happy. But if you merely need debugging information to
657 resolve line numbers there is no loss. Advantage is that
658 build directory object sizes shrink dramatically over a full
659 DEBUG_INFO build and compile times are reduced too.
660 Only works with newer gcc versions.
664 depends on DEBUG_KERNEL
666 Enable this to turn on extended checks in the virtual-memory system
667 that may impact performance.
672 bool "Debug VM translations"
673 depends on DEBUG_KERNEL && X86
675 Enable some costly sanity checks in virtual to page code. This can
676 catch mistakes with virt_to_page() and friends.
680 config DEBUG_NOMMU_REGIONS
681 bool "Debug the global anon/private NOMMU mapping region tree"
682 depends on DEBUG_KERNEL && !MMU
684 This option causes the global tree of anonymous and private mapping
685 regions to be regularly checked for invalid topology.
687 config DEBUG_WRITECOUNT
688 bool "Debug filesystem writers count"
689 depends on DEBUG_KERNEL
691 Enable this to catch wrong use of the writers count in struct
692 vfsmount. This will increase the size of each file struct by
697 config DEBUG_MEMORY_INIT
698 bool "Debug memory initialisation" if EMBEDDED
701 Enable this for additional checks during memory initialisation.
702 The sanity checks verify aspects of the VM such as the memory model
703 and other information provided by the architecture. Verbose
704 information will be printed at KERN_DEBUG loglevel depending
705 on the mminit_loglevel= command-line option.
710 bool "Debug linked list manipulation"
711 depends on DEBUG_KERNEL
713 Enable this to turn on extended checks in the linked-list
719 bool "Debug SG table operations"
720 depends on DEBUG_KERNEL
722 Enable this to turn on checks on scatter-gather tables. This can
723 help find problems with drivers that do not properly initialize
728 config DEBUG_NOTIFIERS
729 bool "Debug notifier call chains"
730 depends on DEBUG_KERNEL
732 Enable this to turn on sanity checking for notifier call chains.
733 This is most useful for kernel developers to make sure that
734 modules properly unregister themselves from notifier chains.
735 This is a relatively cheap check but if you care about maximum
738 config DEBUG_CREDENTIALS
739 bool "Debug credential management"
740 depends on DEBUG_KERNEL
742 Enable this to turn on some debug checking for credential
743 management. The additional code keeps track of the number of
744 pointers from task_structs to any given cred struct, and checks to
745 see that this number never exceeds the usage count of the cred
748 Furthermore, if SELinux is enabled, this also checks that the
749 security pointer in the cred struct is never seen to be invalid.
754 # Select this config option from the architecture Kconfig, if it
755 # it is preferred to always offer frame pointers as a config
756 # option on the architecture (regardless of KERNEL_DEBUG):
758 config ARCH_WANT_FRAME_POINTERS
763 bool "Compile the kernel with frame pointers"
764 depends on DEBUG_KERNEL && \
765 (CRIS || M68K || M68KNOMMU || FRV || UML || \
766 AVR32 || SUPERH || BLACKFIN || MN10300) || \
767 ARCH_WANT_FRAME_POINTERS
768 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
770 If you say Y here the resulting kernel image will be slightly
771 larger and slower, but it gives very useful debugging information
772 in case of kernel bugs. (precise oopses/stacktraces/warnings)
774 config BOOT_PRINTK_DELAY
775 bool "Delay each boot printk message by N milliseconds"
776 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
778 This build option allows you to read kernel boot messages
779 by inserting a short delay after each one. The delay is
780 specified in milliseconds on the kernel command line,
781 using "boot_delay=N".
783 It is likely that you would also need to use "lpj=M" to preset
784 the "loops per jiffie" value.
785 See a previous boot log for the "lpj" value to use for your
786 system, and then set "lpj=M" before setting "boot_delay=N".
787 NOTE: Using this option may adversely affect SMP systems.
788 I.e., processors other than the first one may not boot up.
789 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
790 what it believes to be lockup conditions.
792 config RCU_TORTURE_TEST
793 tristate "torture tests for RCU"
794 depends on DEBUG_KERNEL
797 This option provides a kernel module that runs torture tests
798 on the RCU infrastructure. The kernel module may be built
799 after the fact on the running kernel to be tested, if desired.
801 Say Y here if you want RCU torture tests to be built into
803 Say M if you want the RCU torture tests to build as a module.
804 Say N if you are unsure.
806 config RCU_TORTURE_TEST_RUNNABLE
807 bool "torture tests for RCU runnable by default"
808 depends on RCU_TORTURE_TEST = y
811 This option provides a way to build the RCU torture tests
812 directly into the kernel without them starting up at boot
813 time. You can use /proc/sys/kernel/rcutorture_runnable
814 to manually override this setting. This /proc file is
815 available only when the RCU torture tests have been built
818 Say Y here if you want the RCU torture tests to start during
819 boot (you probably don't).
820 Say N here if you want the RCU torture tests to start only
821 after being manually enabled via /proc.
823 config RCU_CPU_STALL_DETECTOR
824 bool "Check for stalled CPUs delaying RCU grace periods"
825 depends on TREE_RCU || TREE_PREEMPT_RCU
828 This option causes RCU to printk information on which
829 CPUs are delaying the current grace period, but only when
830 the grace period extends for excessive time periods.
832 Say N if you want to disable such checks.
834 Say Y if you are unsure.
836 config RCU_CPU_STALL_VERBOSE
837 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
838 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
841 This option causes RCU to printk detailed per-task information
842 for any tasks that are stalling the current RCU grace period.
844 Say N if you are unsure.
846 Say Y if you want to enable such checks.
848 config KPROBES_SANITY_TEST
849 bool "Kprobes sanity tests"
850 depends on DEBUG_KERNEL
854 This option provides for testing basic kprobes functionality on
855 boot. A sample kprobe, jprobe and kretprobe are inserted and
856 verified for functionality.
858 Say N if you are unsure.
860 config BACKTRACE_SELF_TEST
861 tristate "Self test for the backtrace code"
862 depends on DEBUG_KERNEL
865 This option provides a kernel module that can be used to test
866 the kernel stack backtrace code. This option is not useful
867 for distributions or general kernels, but only for kernel
868 developers working on architecture code.
870 Note that if you want to also test saved backtraces, you will
871 have to enable STACKTRACE as well.
873 Say N if you are unsure.
875 config DEBUG_BLOCK_EXT_DEVT
876 bool "Force extended block device numbers and spread them"
877 depends on DEBUG_KERNEL
881 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
882 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
883 YOU ARE DOING. Distros, please enable this and fix whatever
886 Conventionally, block device numbers are allocated from
887 predetermined contiguous area. However, extended block area
888 may introduce non-contiguous block device numbers. This
889 option forces most block device numbers to be allocated from
890 the extended space and spreads them to discover kernel or
891 userland code paths which assume predetermined contiguous
892 device number allocation.
894 Note that turning on this debug option shuffles all the
895 device numbers for all IDE and SCSI devices including libata
896 ones, so root partition specified using device number
897 directly (via rdev or root=MAJ:MIN) won't work anymore.
898 Textual device names (root=/dev/sdXn) will continue to work.
900 Say N if you are unsure.
902 config DEBUG_FORCE_WEAK_PER_CPU
903 bool "Force weak per-cpu definitions"
904 depends on DEBUG_KERNEL
906 s390 and alpha require percpu variables in modules to be
907 defined weak to work around addressing range issue which
908 puts the following two restrictions on percpu variable
911 1. percpu symbols must be unique whether static or not
912 2. percpu variables can't be defined inside a function
914 To ensure that generic code follows the above rules, this
915 option forces all percpu variables to be defined as weak.
918 tristate "Linux Kernel Dump Test Tool Module"
923 This module enables testing of the different dumping mechanisms by
924 inducing system failures at predefined crash points.
925 If you don't need it: say N
926 Choose M here to compile this code as a module. The module will be
929 Documentation on how to use the module can be found in
930 Documentation/fault-injection/provoke-crashes.txt
932 config CPU_NOTIFIER_ERROR_INJECT
933 tristate "CPU notifier error injection module"
934 depends on HOTPLUG_CPU && DEBUG_KERNEL
936 This option provides a kernel module that can be used to test
937 the error handling of the cpu notifiers
939 To compile this code as a module, choose M here: the module will
940 be called cpu-notifier-error-inject.
944 config FAULT_INJECTION
945 bool "Fault-injection framework"
946 depends on DEBUG_KERNEL
948 Provide fault-injection framework.
949 For more details, see Documentation/fault-injection/.
952 bool "Fault-injection capability for kmalloc"
953 depends on FAULT_INJECTION
954 depends on SLAB || SLUB
956 Provide fault-injection capability for kmalloc.
958 config FAIL_PAGE_ALLOC
959 bool "Fault-injection capabilitiy for alloc_pages()"
960 depends on FAULT_INJECTION
962 Provide fault-injection capability for alloc_pages().
964 config FAIL_MAKE_REQUEST
965 bool "Fault-injection capability for disk IO"
966 depends on FAULT_INJECTION && BLOCK
968 Provide fault-injection capability for disk IO.
970 config FAIL_IO_TIMEOUT
971 bool "Fault-injection capability for faking disk interrupts"
972 depends on FAULT_INJECTION && BLOCK
974 Provide fault-injection capability on end IO handling. This
975 will make the block layer "forget" an interrupt as configured,
976 thus exercising the error handling.
978 Only works with drivers that use the generic timeout handling,
979 for others it wont do anything.
981 config FAULT_INJECTION_DEBUG_FS
982 bool "Debugfs entries for fault-injection capabilities"
983 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
985 Enable configuration of fault-injection capabilities via debugfs.
987 config FAULT_INJECTION_STACKTRACE_FILTER
988 bool "stacktrace filter for fault-injection capabilities"
989 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
992 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
994 Provide stacktrace filter for fault-injection capabilities
997 bool "Latency measuring infrastructure"
998 depends on HAVE_LATENCYTOP_SUPPORT
999 depends on DEBUG_KERNEL
1000 depends on STACKTRACE_SUPPORT
1002 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
1009 Enable this option if you want to use the LatencyTOP tool
1010 to find out which userspace is blocking on what kernel operations.
1012 config SYSCTL_SYSCALL_CHECK
1013 bool "Sysctl checks"
1016 sys_sysctl uses binary paths that have been found challenging
1017 to properly maintain and use. This enables checks that help
1018 you to keep things correct.
1020 source mm/Kconfig.debug
1021 source kernel/trace/Kconfig
1023 config PROVIDE_OHCI1394_DMA_INIT
1024 bool "Remote debugging over FireWire early on boot"
1025 depends on PCI && X86
1027 If you want to debug problems which hang or crash the kernel early
1028 on boot and the crashing machine has a FireWire port, you can use
1029 this feature to remotely access the memory of the crashed machine
1030 over FireWire. This employs remote DMA as part of the OHCI1394
1031 specification which is now the standard for FireWire controllers.
1033 With remote DMA, you can monitor the printk buffer remotely using
1034 firescope and access all memory below 4GB using fireproxy from gdb.
1035 Even controlling a kernel debugger is possible using remote DMA.
1039 If ohci1394_dma=early is used as boot parameter, it will initialize
1040 all OHCI1394 controllers which are found in the PCI config space.
1042 As all changes to the FireWire bus such as enabling and disabling
1043 devices cause a bus reset and thereby disable remote DMA for all
1044 devices, be sure to have the cable plugged and FireWire enabled on
1045 the debugging host before booting the debug target for debugging.
1047 This code (~1k) is freed after boot. By then, the firewire stack
1048 in charge of the OHCI-1394 controllers should be used instead.
1050 See Documentation/debugging-via-ohci1394.txt for more information.
1052 config FIREWIRE_OHCI_REMOTE_DMA
1053 bool "Remote debugging over FireWire with firewire-ohci"
1054 depends on FIREWIRE_OHCI
1056 This option lets you use the FireWire bus for remote debugging
1057 with help of the firewire-ohci driver. It enables unfiltered
1058 remote DMA in firewire-ohci.
1059 See Documentation/debugging-via-ohci1394.txt for more information.
1064 bool "Build targets in Documentation/ tree"
1065 depends on HEADERS_CHECK
1067 This option attempts to build objects from the source files in the
1068 kernel Documentation/ tree.
1070 Say N if you are unsure.
1072 config DYNAMIC_DEBUG
1073 bool "Enable dynamic printk() support"
1079 Compiles debug level messages into the kernel, which would not
1080 otherwise be available at runtime. These messages can then be
1081 enabled/disabled based on various levels of scope - per source file,
1082 function, module, format string, and line number. This mechanism
1083 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1084 this compile option is a larger kernel text size of about 2%.
1088 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1089 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1090 filesystem must first be mounted before making use of this feature.
1091 We refer the control file as: <debugfs>/dynamic_debug/control. This
1092 file contains a list of the debug statements that can be enabled. The
1093 format for each line of the file is:
1095 filename:lineno [module]function flags format
1097 filename : source file of the debug statement
1098 lineno : line number of the debug statement
1099 module : module that contains the debug statement
1100 function : function that contains the debug statement
1101 flags : 'p' means the line is turned 'on' for printing
1102 format : the format used for the debug statement
1106 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1107 # filename:lineno [module]function flags format
1108 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1109 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1110 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1114 // enable the message at line 1603 of file svcsock.c
1115 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1116 <debugfs>/dynamic_debug/control
1118 // enable all the messages in file svcsock.c
1119 nullarbor:~ # echo -n 'file svcsock.c +p' >
1120 <debugfs>/dynamic_debug/control
1122 // enable all the messages in the NFS server module
1123 nullarbor:~ # echo -n 'module nfsd +p' >
1124 <debugfs>/dynamic_debug/control
1126 // enable all 12 messages in the function svc_process()
1127 nullarbor:~ # echo -n 'func svc_process +p' >
1128 <debugfs>/dynamic_debug/control
1130 // disable all 12 messages in the function svc_process()
1131 nullarbor:~ # echo -n 'func svc_process -p' >
1132 <debugfs>/dynamic_debug/control
1134 See Documentation/dynamic-debug-howto.txt for additional information.
1136 config DMA_API_DEBUG
1137 bool "Enable debugging of DMA-API usage"
1138 depends on HAVE_DMA_API_DEBUG
1140 Enable this option to debug the use of the DMA API by device drivers.
1141 With this option you will be able to detect common bugs in device
1142 drivers like double-freeing of DMA mappings or freeing mappings that
1143 were never allocated.
1144 This option causes a performance degredation. Use only if you want
1145 to debug device drivers. If unsure, say N.
1147 config ATOMIC64_SELFTEST
1148 bool "Perform an atomic64_t self-test at boot"
1150 Enable this option to test the atomic64_t functions at boot.
1154 source "samples/Kconfig"
1156 source "lib/Kconfig.kgdb"
1158 source "lib/Kconfig.kmemcheck"