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"
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 DETECT_SOFTLOCKUP
155 bool "Detect Soft Lockups"
156 depends on DEBUG_KERNEL && !S390
159 Say Y here to enable the kernel to detect "soft lockups",
160 which are bugs that cause the kernel to loop in kernel
161 mode for more than 60 seconds, without giving other tasks a
164 When a soft-lockup is detected, the kernel will print the
165 current stack trace (which you should report), but the
166 system will stay locked up. This feature has negligible
169 (Note that "hard lockups" are separate type of bugs that
170 can be detected via the NMI-watchdog, on platforms that
174 bool "Detect Hard Lockups with an NMI Watchdog"
175 depends on DEBUG_KERNEL && PERF_EVENTS && PERF_EVENTS_NMI
178 Say Y here to enable the kernel to use the NMI as a watchdog
179 to detect hard lockups. This is useful when a cpu hangs for no
180 reason but can still respond to NMIs. A backtrace is displayed
181 for reviewing and reporting.
183 The overhead should be minimal, just an extra NMI every few
186 config BOOTPARAM_SOFTLOCKUP_PANIC
187 bool "Panic (Reboot) On Soft Lockups"
188 depends on DETECT_SOFTLOCKUP
190 Say Y here to enable the kernel to panic on "soft lockups",
191 which are bugs that cause the kernel to loop in kernel
192 mode for more than 60 seconds, without giving other tasks a
195 The panic can be used in combination with panic_timeout,
196 to cause the system to reboot automatically after a
197 lockup has been detected. This feature is useful for
198 high-availability systems that have uptime guarantees and
199 where a lockup must be resolved ASAP.
203 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
205 depends on DETECT_SOFTLOCKUP
207 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
208 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
210 config DETECT_HUNG_TASK
211 bool "Detect Hung Tasks"
212 depends on DEBUG_KERNEL
213 default DETECT_SOFTLOCKUP
215 Say Y here to enable the kernel to detect "hung tasks",
216 which are bugs that cause the task to be stuck in
217 uninterruptible "D" state indefinitiley.
219 When a hung task is detected, the kernel will print the
220 current stack trace (which you should report), but the
221 task will stay in uninterruptible state. If lockdep is
222 enabled then all held locks will also be reported. This
223 feature has negligible overhead.
225 config BOOTPARAM_HUNG_TASK_PANIC
226 bool "Panic (Reboot) On Hung Tasks"
227 depends on DETECT_HUNG_TASK
229 Say Y here to enable the kernel to panic on "hung tasks",
230 which are bugs that cause the kernel to leave a task stuck
231 in uninterruptible "D" state.
233 The panic can be used in combination with panic_timeout,
234 to cause the system to reboot automatically after a
235 hung task has been detected. This feature is useful for
236 high-availability systems that have uptime guarantees and
237 where a hung tasks must be resolved ASAP.
241 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
243 depends on DETECT_HUNG_TASK
245 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
246 default 1 if BOOTPARAM_HUNG_TASK_PANIC
249 bool "Collect scheduler debugging info"
250 depends on DEBUG_KERNEL && PROC_FS
253 If you say Y here, the /proc/sched_debug file will be provided
254 that can help debug the scheduler. The runtime overhead of this
258 bool "Collect scheduler statistics"
259 depends on DEBUG_KERNEL && PROC_FS
261 If you say Y here, additional code will be inserted into the
262 scheduler and related routines to collect statistics about
263 scheduler behavior and provide them in /proc/schedstat. These
264 stats may be useful for both tuning and debugging the scheduler
265 If you aren't debugging the scheduler or trying to tune a specific
266 application, you can say N to avoid the very slight overhead
270 bool "Collect kernel timers statistics"
271 depends on DEBUG_KERNEL && PROC_FS
273 If you say Y here, additional code will be inserted into the
274 timer routines to collect statistics about kernel timers being
275 reprogrammed. The statistics can be read from /proc/timer_stats.
276 The statistics collection is started by writing 1 to /proc/timer_stats,
277 writing 0 stops it. This feature is useful to collect information
278 about timer usage patterns in kernel and userspace. This feature
279 is lightweight if enabled in the kernel config but not activated
280 (it defaults to deactivated on bootup and will only be activated
281 if some application like powertop activates it explicitly).
284 bool "Debug object operations"
285 depends on DEBUG_KERNEL
287 If you say Y here, additional code will be inserted into the
288 kernel to track the life time of various objects and validate
289 the operations on those objects.
291 config DEBUG_OBJECTS_SELFTEST
292 bool "Debug objects selftest"
293 depends on DEBUG_OBJECTS
295 This enables the selftest of the object debug code.
297 config DEBUG_OBJECTS_FREE
298 bool "Debug objects in freed memory"
299 depends on DEBUG_OBJECTS
301 This enables checks whether a k/v free operation frees an area
302 which contains an object which has not been deactivated
303 properly. This can make kmalloc/kfree-intensive workloads
306 config DEBUG_OBJECTS_TIMERS
307 bool "Debug timer objects"
308 depends on DEBUG_OBJECTS
310 If you say Y here, additional code will be inserted into the
311 timer routines to track the life time of timer objects and
312 validate the timer operations.
314 config DEBUG_OBJECTS_WORK
315 bool "Debug work objects"
316 depends on DEBUG_OBJECTS
318 If you say Y here, additional code will be inserted into the
319 work queue routines to track the life time of work objects and
320 validate the work operations.
322 config DEBUG_OBJECTS_ENABLE_DEFAULT
323 int "debug_objects bootup default value (0-1)"
326 depends on DEBUG_OBJECTS
328 Debug objects boot parameter default value
331 bool "Debug slab memory allocations"
332 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
334 Say Y here to have the kernel do limited verification on memory
335 allocation as well as poisoning memory on free to catch use of freed
336 memory. This can make kmalloc/kfree-intensive workloads much slower.
338 config DEBUG_SLAB_LEAK
339 bool "Memory leak debugging"
340 depends on DEBUG_SLAB
343 bool "SLUB debugging on by default"
344 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
347 Boot with debugging on by default. SLUB boots by default with
348 the runtime debug capabilities switched off. Enabling this is
349 equivalent to specifying the "slub_debug" parameter on boot.
350 There is no support for more fine grained debug control like
351 possible with slub_debug=xxx. SLUB debugging may be switched
352 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
357 bool "Enable SLUB performance statistics"
358 depends on SLUB && SLUB_DEBUG && SYSFS
360 SLUB statistics are useful to debug SLUBs allocation behavior in
361 order find ways to optimize the allocator. This should never be
362 enabled for production use since keeping statistics slows down
363 the allocator by a few percentage points. The slabinfo command
364 supports the determination of the most active slabs to figure
365 out which slabs are relevant to a particular load.
366 Try running: slabinfo -DA
368 config DEBUG_KMEMLEAK
369 bool "Kernel memory leak detector"
370 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
371 (X86 || ARM || PPC || S390)
373 select DEBUG_FS if SYSFS
374 select STACKTRACE if STACKTRACE_SUPPORT
378 Say Y here if you want to enable the memory leak
379 detector. The memory allocation/freeing is traced in a way
380 similar to the Boehm's conservative garbage collector, the
381 difference being that the orphan objects are not freed but
382 only shown in /sys/kernel/debug/kmemleak. Enabling this
383 feature will introduce an overhead to memory
384 allocations. See Documentation/kmemleak.txt for more
387 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
388 of finding leaks due to the slab objects poisoning.
390 In order to access the kmemleak file, debugfs needs to be
391 mounted (usually at /sys/kernel/debug).
393 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
394 int "Maximum kmemleak early log entries"
395 depends on DEBUG_KMEMLEAK
399 Kmemleak must track all the memory allocations to avoid
400 reporting false positives. Since memory may be allocated or
401 freed before kmemleak is initialised, an early log buffer is
402 used to store these actions. If kmemleak reports "early log
403 buffer exceeded", please increase this value.
405 config DEBUG_KMEMLEAK_TEST
406 tristate "Simple test for the kernel memory leak detector"
407 depends on DEBUG_KMEMLEAK
409 Say Y or M here to build a test for the kernel memory leak
410 detector. This option enables a module that explicitly leaks
416 bool "Debug preemptible kernel"
417 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
420 If you say Y here then the kernel will use a debug variant of the
421 commonly used smp_processor_id() function and will print warnings
422 if kernel code uses it in a preemption-unsafe way. Also, the kernel
423 will detect preemption count underflows.
425 config DEBUG_RT_MUTEXES
426 bool "RT Mutex debugging, deadlock detection"
427 depends on DEBUG_KERNEL && RT_MUTEXES
429 This allows rt mutex semantics violations and rt mutex related
430 deadlocks (lockups) to be detected and reported automatically.
435 depends on DEBUG_RT_MUTEXES
437 config RT_MUTEX_TESTER
438 bool "Built-in scriptable tester for rt-mutexes"
439 depends on DEBUG_KERNEL && RT_MUTEXES
441 This option enables a rt-mutex tester.
443 config DEBUG_SPINLOCK
444 bool "Spinlock and rw-lock debugging: basic checks"
445 depends on DEBUG_KERNEL
447 Say Y here and build SMP to catch missing spinlock initialization
448 and certain other kinds of spinlock errors commonly made. This is
449 best used in conjunction with the NMI watchdog so that spinlock
450 deadlocks are also debuggable.
453 bool "Mutex debugging: basic checks"
454 depends on DEBUG_KERNEL
456 This feature allows mutex semantics violations to be detected and
459 config DEBUG_LOCK_ALLOC
460 bool "Lock debugging: detect incorrect freeing of live locks"
461 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
462 select DEBUG_SPINLOCK
466 This feature will check whether any held lock (spinlock, rwlock,
467 mutex or rwsem) is incorrectly freed by the kernel, via any of the
468 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
469 vfree(), etc.), whether a live lock is incorrectly reinitialized via
470 spin_lock_init()/mutex_init()/etc., or whether there is any lock
471 held during task exit.
474 bool "Lock debugging: prove locking correctness"
475 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
477 select DEBUG_SPINLOCK
479 select DEBUG_LOCK_ALLOC
482 This feature enables the kernel to prove that all locking
483 that occurs in the kernel runtime is mathematically
484 correct: that under no circumstance could an arbitrary (and
485 not yet triggered) combination of observed locking
486 sequences (on an arbitrary number of CPUs, running an
487 arbitrary number of tasks and interrupt contexts) cause a
490 In short, this feature enables the kernel to report locking
491 related deadlocks before they actually occur.
493 The proof does not depend on how hard and complex a
494 deadlock scenario would be to trigger: how many
495 participant CPUs, tasks and irq-contexts would be needed
496 for it to trigger. The proof also does not depend on
497 timing: if a race and a resulting deadlock is possible
498 theoretically (no matter how unlikely the race scenario
499 is), it will be proven so and will immediately be
500 reported by the kernel (once the event is observed that
501 makes the deadlock theoretically possible).
503 If a deadlock is impossible (i.e. the locking rules, as
504 observed by the kernel, are mathematically correct), the
505 kernel reports nothing.
507 NOTE: this feature can also be enabled for rwlocks, mutexes
508 and rwsems - in which case all dependencies between these
509 different locking variants are observed and mapped too, and
510 the proof of observed correctness is also maintained for an
511 arbitrary combination of these separate locking variants.
513 For more details, see Documentation/lockdep-design.txt.
517 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
519 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
524 bool "Lock usage statistics"
525 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
527 select DEBUG_SPINLOCK
529 select DEBUG_LOCK_ALLOC
532 This feature enables tracking lock contention points
534 For more details, see Documentation/lockstat.txt
537 bool "Lock dependency engine debugging"
538 depends on DEBUG_KERNEL && LOCKDEP
540 If you say Y here, the lock dependency engine will do
541 additional runtime checks to debug itself, at the price
542 of more runtime overhead.
544 config TRACE_IRQFLAGS
545 depends on DEBUG_KERNEL
548 depends on TRACE_IRQFLAGS_SUPPORT
549 depends on PROVE_LOCKING
551 config DEBUG_SPINLOCK_SLEEP
552 bool "Spinlock debugging: sleep-inside-spinlock checking"
553 depends on DEBUG_KERNEL
555 If you say Y here, various routines which may sleep will become very
556 noisy if they are called with a spinlock held.
558 config DEBUG_LOCKING_API_SELFTESTS
559 bool "Locking API boot-time self-tests"
560 depends on DEBUG_KERNEL
562 Say Y here if you want the kernel to run a short self-test during
563 bootup. The self-test checks whether common types of locking bugs
564 are detected by debugging mechanisms or not. (if you disable
565 lock debugging then those bugs wont be detected of course.)
566 The following locking APIs are covered: spinlocks, rwlocks,
571 depends on STACKTRACE_SUPPORT
574 bool "kobject debugging"
575 depends on DEBUG_KERNEL
577 If you say Y here, some extra kobject debugging messages will be sent
581 bool "Highmem debugging"
582 depends on DEBUG_KERNEL && HIGHMEM
584 This options enables addition error checking for high memory systems.
585 Disable for production systems.
587 config DEBUG_BUGVERBOSE
588 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
590 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
591 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
594 Say Y here to make BUG() panics output the file name and line number
595 of the BUG call as well as the EIP and oops trace. This aids
596 debugging but costs about 70-100K of memory.
599 bool "Compile the kernel with debug info"
600 depends on DEBUG_KERNEL
602 If you say Y here the resulting kernel image will include
603 debugging info resulting in a larger kernel image.
604 This adds debug symbols to the kernel and modules (gcc -g), and
605 is needed if you intend to use kernel crashdump or binary object
606 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
607 Say Y here only if you plan to debug the kernel.
613 depends on DEBUG_KERNEL
615 Enable this to turn on extended checks in the virtual-memory system
616 that may impact performance.
621 bool "Debug VM translations"
622 depends on DEBUG_KERNEL && X86
624 Enable some costly sanity checks in virtual to page code. This can
625 catch mistakes with virt_to_page() and friends.
629 config DEBUG_NOMMU_REGIONS
630 bool "Debug the global anon/private NOMMU mapping region tree"
631 depends on DEBUG_KERNEL && !MMU
633 This option causes the global tree of anonymous and private mapping
634 regions to be regularly checked for invalid topology.
636 config DEBUG_WRITECOUNT
637 bool "Debug filesystem writers count"
638 depends on DEBUG_KERNEL
640 Enable this to catch wrong use of the writers count in struct
641 vfsmount. This will increase the size of each file struct by
646 config DEBUG_MEMORY_INIT
647 bool "Debug memory initialisation" if EMBEDDED
650 Enable this for additional checks during memory initialisation.
651 The sanity checks verify aspects of the VM such as the memory model
652 and other information provided by the architecture. Verbose
653 information will be printed at KERN_DEBUG loglevel depending
654 on the mminit_loglevel= command-line option.
659 bool "Debug linked list manipulation"
660 depends on DEBUG_KERNEL
662 Enable this to turn on extended checks in the linked-list
668 bool "Debug SG table operations"
669 depends on DEBUG_KERNEL
671 Enable this to turn on checks on scatter-gather tables. This can
672 help find problems with drivers that do not properly initialize
677 config DEBUG_NOTIFIERS
678 bool "Debug notifier call chains"
679 depends on DEBUG_KERNEL
681 Enable this to turn on sanity checking for notifier call chains.
682 This is most useful for kernel developers to make sure that
683 modules properly unregister themselves from notifier chains.
684 This is a relatively cheap check but if you care about maximum
687 config DEBUG_CREDENTIALS
688 bool "Debug credential management"
689 depends on DEBUG_KERNEL
691 Enable this to turn on some debug checking for credential
692 management. The additional code keeps track of the number of
693 pointers from task_structs to any given cred struct, and checks to
694 see that this number never exceeds the usage count of the cred
697 Furthermore, if SELinux is enabled, this also checks that the
698 security pointer in the cred struct is never seen to be invalid.
703 # Select this config option from the architecture Kconfig, if it
704 # it is preferred to always offer frame pointers as a config
705 # option on the architecture (regardless of KERNEL_DEBUG):
707 config ARCH_WANT_FRAME_POINTERS
712 bool "Compile the kernel with frame pointers"
713 depends on DEBUG_KERNEL && \
714 (CRIS || M68K || M68KNOMMU || FRV || UML || \
715 AVR32 || SUPERH || BLACKFIN || MN10300) || \
716 ARCH_WANT_FRAME_POINTERS
717 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
719 If you say Y here the resulting kernel image will be slightly
720 larger and slower, but it gives very useful debugging information
721 in case of kernel bugs. (precise oopses/stacktraces/warnings)
723 config BOOT_PRINTK_DELAY
724 bool "Delay each boot printk message by N milliseconds"
725 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
727 This build option allows you to read kernel boot messages
728 by inserting a short delay after each one. The delay is
729 specified in milliseconds on the kernel command line,
730 using "boot_delay=N".
732 It is likely that you would also need to use "lpj=M" to preset
733 the "loops per jiffie" value.
734 See a previous boot log for the "lpj" value to use for your
735 system, and then set "lpj=M" before setting "boot_delay=N".
736 NOTE: Using this option may adversely affect SMP systems.
737 I.e., processors other than the first one may not boot up.
738 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
739 what it believes to be lockup conditions.
741 config RCU_TORTURE_TEST
742 tristate "torture tests for RCU"
743 depends on DEBUG_KERNEL
746 This option provides a kernel module that runs torture tests
747 on the RCU infrastructure. The kernel module may be built
748 after the fact on the running kernel to be tested, if desired.
750 Say Y here if you want RCU torture tests to be built into
752 Say M if you want the RCU torture tests to build as a module.
753 Say N if you are unsure.
755 config RCU_TORTURE_TEST_RUNNABLE
756 bool "torture tests for RCU runnable by default"
757 depends on RCU_TORTURE_TEST = y
760 This option provides a way to build the RCU torture tests
761 directly into the kernel without them starting up at boot
762 time. You can use /proc/sys/kernel/rcutorture_runnable
763 to manually override this setting. This /proc file is
764 available only when the RCU torture tests have been built
767 Say Y here if you want the RCU torture tests to start during
768 boot (you probably don't).
769 Say N here if you want the RCU torture tests to start only
770 after being manually enabled via /proc.
772 config RCU_CPU_STALL_DETECTOR
773 bool "Check for stalled CPUs delaying RCU grace periods"
774 depends on TREE_RCU || TREE_PREEMPT_RCU
777 This option causes RCU to printk information on which
778 CPUs are delaying the current grace period, but only when
779 the grace period extends for excessive time periods.
781 Say Y if you want RCU to perform such checks.
783 Say N if you are unsure.
785 config KPROBES_SANITY_TEST
786 bool "Kprobes sanity tests"
787 depends on DEBUG_KERNEL
791 This option provides for testing basic kprobes functionality on
792 boot. A sample kprobe, jprobe and kretprobe are inserted and
793 verified for functionality.
795 Say N if you are unsure.
797 config BACKTRACE_SELF_TEST
798 tristate "Self test for the backtrace code"
799 depends on DEBUG_KERNEL
802 This option provides a kernel module that can be used to test
803 the kernel stack backtrace code. This option is not useful
804 for distributions or general kernels, but only for kernel
805 developers working on architecture code.
807 Note that if you want to also test saved backtraces, you will
808 have to enable STACKTRACE as well.
810 Say N if you are unsure.
812 config DEBUG_BLOCK_EXT_DEVT
813 bool "Force extended block device numbers and spread them"
814 depends on DEBUG_KERNEL
818 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
819 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
820 YOU ARE DOING. Distros, please enable this and fix whatever
823 Conventionally, block device numbers are allocated from
824 predetermined contiguous area. However, extended block area
825 may introduce non-contiguous block device numbers. This
826 option forces most block device numbers to be allocated from
827 the extended space and spreads them to discover kernel or
828 userland code paths which assume predetermined contiguous
829 device number allocation.
831 Note that turning on this debug option shuffles all the
832 device numbers for all IDE and SCSI devices including libata
833 ones, so root partition specified using device number
834 directly (via rdev or root=MAJ:MIN) won't work anymore.
835 Textual device names (root=/dev/sdXn) will continue to work.
837 Say N if you are unsure.
839 config DEBUG_FORCE_WEAK_PER_CPU
840 bool "Force weak per-cpu definitions"
841 depends on DEBUG_KERNEL
843 s390 and alpha require percpu variables in modules to be
844 defined weak to work around addressing range issue which
845 puts the following two restrictions on percpu variable
848 1. percpu symbols must be unique whether static or not
849 2. percpu variables can't be defined inside a function
851 To ensure that generic code follows the above rules, this
852 option forces all percpu variables to be defined as weak.
855 tristate "Linux Kernel Dump Test Tool Module"
856 depends on DEBUG_KERNEL
861 This module enables testing of the different dumping mechanisms by
862 inducing system failures at predefined crash points.
863 If you don't need it: say N
864 Choose M here to compile this code as a module. The module will be
867 Documentation on how to use the module can be found in
870 config FAULT_INJECTION
871 bool "Fault-injection framework"
872 depends on DEBUG_KERNEL
874 Provide fault-injection framework.
875 For more details, see Documentation/fault-injection/.
878 bool "Fault-injection capability for kmalloc"
879 depends on FAULT_INJECTION
880 depends on SLAB || SLUB
882 Provide fault-injection capability for kmalloc.
884 config FAIL_PAGE_ALLOC
885 bool "Fault-injection capabilitiy for alloc_pages()"
886 depends on FAULT_INJECTION
888 Provide fault-injection capability for alloc_pages().
890 config FAIL_MAKE_REQUEST
891 bool "Fault-injection capability for disk IO"
892 depends on FAULT_INJECTION && BLOCK
894 Provide fault-injection capability for disk IO.
896 config FAIL_IO_TIMEOUT
897 bool "Faul-injection capability for faking disk interrupts"
898 depends on FAULT_INJECTION && BLOCK
900 Provide fault-injection capability on end IO handling. This
901 will make the block layer "forget" an interrupt as configured,
902 thus exercising the error handling.
904 Only works with drivers that use the generic timeout handling,
905 for others it wont do anything.
907 config FAULT_INJECTION_DEBUG_FS
908 bool "Debugfs entries for fault-injection capabilities"
909 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
911 Enable configuration of fault-injection capabilities via debugfs.
913 config FAULT_INJECTION_STACKTRACE_FILTER
914 bool "stacktrace filter for fault-injection capabilities"
915 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
918 select FRAME_POINTER if !PPC && !S390
920 Provide stacktrace filter for fault-injection capabilities
923 bool "Latency measuring infrastructure"
924 select FRAME_POINTER if !MIPS && !PPC && !S390
930 depends on HAVE_LATENCYTOP_SUPPORT
932 Enable this option if you want to use the LatencyTOP tool
933 to find out which userspace is blocking on what kernel operations.
935 config SYSCTL_SYSCALL_CHECK
939 sys_sysctl uses binary paths that have been found challenging
940 to properly maintain and use. This enables checks that help
941 you to keep things correct.
943 source mm/Kconfig.debug
944 source kernel/trace/Kconfig
946 config PROVIDE_OHCI1394_DMA_INIT
947 bool "Remote debugging over FireWire early on boot"
948 depends on PCI && X86
950 If you want to debug problems which hang or crash the kernel early
951 on boot and the crashing machine has a FireWire port, you can use
952 this feature to remotely access the memory of the crashed machine
953 over FireWire. This employs remote DMA as part of the OHCI1394
954 specification which is now the standard for FireWire controllers.
956 With remote DMA, you can monitor the printk buffer remotely using
957 firescope and access all memory below 4GB using fireproxy from gdb.
958 Even controlling a kernel debugger is possible using remote DMA.
962 If ohci1394_dma=early is used as boot parameter, it will initialize
963 all OHCI1394 controllers which are found in the PCI config space.
965 As all changes to the FireWire bus such as enabling and disabling
966 devices cause a bus reset and thereby disable remote DMA for all
967 devices, be sure to have the cable plugged and FireWire enabled on
968 the debugging host before booting the debug target for debugging.
970 This code (~1k) is freed after boot. By then, the firewire stack
971 in charge of the OHCI-1394 controllers should be used instead.
973 See Documentation/debugging-via-ohci1394.txt for more information.
975 config FIREWIRE_OHCI_REMOTE_DMA
976 bool "Remote debugging over FireWire with firewire-ohci"
977 depends on FIREWIRE_OHCI
979 This option lets you use the FireWire bus for remote debugging
980 with help of the firewire-ohci driver. It enables unfiltered
981 remote DMA in firewire-ohci.
982 See Documentation/debugging-via-ohci1394.txt for more information.
987 bool "Build targets in Documentation/ tree"
988 depends on HEADERS_CHECK
990 This option attempts to build objects from the source files in the
991 kernel Documentation/ tree.
993 Say N if you are unsure.
996 bool "Enable dynamic printk() support"
1002 Compiles debug level messages into the kernel, which would not
1003 otherwise be available at runtime. These messages can then be
1004 enabled/disabled based on various levels of scope - per source file,
1005 function, module, format string, and line number. This mechanism
1006 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1007 this compile option is a larger kernel text size of about 2%.
1011 Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
1012 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1013 filesystem must first be mounted before making use of this feature.
1014 We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
1015 file contains a list of the debug statements that can be enabled. The
1016 format for each line of the file is:
1018 filename:lineno [module]function flags format
1020 filename : source file of the debug statement
1021 lineno : line number of the debug statement
1022 module : module that contains the debug statement
1023 function : function that contains the debug statement
1024 flags : 'p' means the line is turned 'on' for printing
1025 format : the format used for the debug statement
1029 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
1030 # filename:lineno [module]function flags format
1031 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1032 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1033 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1037 // enable the message at line 1603 of file svcsock.c
1038 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1039 <debugfs>/dynamic_debug/ddebug
1041 // enable all the messages in file svcsock.c
1042 nullarbor:~ # echo -n 'file svcsock.c +p' >
1043 <debugfs>/dynamic_debug/ddebug
1045 // enable all the messages in the NFS server module
1046 nullarbor:~ # echo -n 'module nfsd +p' >
1047 <debugfs>/dynamic_debug/ddebug
1049 // enable all 12 messages in the function svc_process()
1050 nullarbor:~ # echo -n 'func svc_process +p' >
1051 <debugfs>/dynamic_debug/ddebug
1053 // disable all 12 messages in the function svc_process()
1054 nullarbor:~ # echo -n 'func svc_process -p' >
1055 <debugfs>/dynamic_debug/ddebug
1057 See Documentation/dynamic-debug-howto.txt for additional information.
1059 config DMA_API_DEBUG
1060 bool "Enable debugging of DMA-API usage"
1061 depends on HAVE_DMA_API_DEBUG
1063 Enable this option to debug the use of the DMA API by device drivers.
1064 With this option you will be able to detect common bugs in device
1065 drivers like double-freeing of DMA mappings or freeing mappings that
1066 were never allocated.
1067 This option causes a performance degredation. Use only if you want
1068 to debug device drivers. If unsure, say N.
1070 source "samples/Kconfig"
1072 source "lib/Kconfig.kgdb"
1074 source "lib/Kconfig.kmemcheck"