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 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
173 config BOOTPARAM_SOFTLOCKUP_PANIC
174 bool "Panic (Reboot) On Soft Lockups"
175 depends on DETECT_SOFTLOCKUP
177 Say Y here to enable the kernel to panic on "soft lockups",
178 which are bugs that cause the kernel to loop in kernel
179 mode for more than 60 seconds, without giving other tasks a
182 The panic can be used in combination with panic_timeout,
183 to cause the system to reboot automatically after a
184 lockup has been detected. This feature is useful for
185 high-availability systems that have uptime guarantees and
186 where a lockup must be resolved ASAP.
190 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
192 depends on DETECT_SOFTLOCKUP
194 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
195 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
197 config DETECT_HUNG_TASK
198 bool "Detect Hung Tasks"
199 depends on DEBUG_KERNEL
200 default DETECT_SOFTLOCKUP
202 Say Y here to enable the kernel to detect "hung tasks",
203 which are bugs that cause the task to be stuck in
204 uninterruptible "D" state indefinitiley.
206 When a hung task is detected, the kernel will print the
207 current stack trace (which you should report), but the
208 task will stay in uninterruptible state. If lockdep is
209 enabled then all held locks will also be reported. This
210 feature has negligible overhead.
212 config BOOTPARAM_HUNG_TASK_PANIC
213 bool "Panic (Reboot) On Hung Tasks"
214 depends on DETECT_HUNG_TASK
216 Say Y here to enable the kernel to panic on "hung tasks",
217 which are bugs that cause the kernel to leave a task stuck
218 in uninterruptible "D" state.
220 The panic can be used in combination with panic_timeout,
221 to cause the system to reboot automatically after a
222 hung task has been detected. This feature is useful for
223 high-availability systems that have uptime guarantees and
224 where a hung tasks must be resolved ASAP.
228 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
230 depends on DETECT_HUNG_TASK
232 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
233 default 1 if BOOTPARAM_HUNG_TASK_PANIC
236 bool "Collect scheduler debugging info"
237 depends on DEBUG_KERNEL && PROC_FS
240 If you say Y here, the /proc/sched_debug file will be provided
241 that can help debug the scheduler. The runtime overhead of this
245 bool "Collect scheduler statistics"
246 depends on DEBUG_KERNEL && PROC_FS
248 If you say Y here, additional code will be inserted into the
249 scheduler and related routines to collect statistics about
250 scheduler behavior and provide them in /proc/schedstat. These
251 stats may be useful for both tuning and debugging the scheduler
252 If you aren't debugging the scheduler or trying to tune a specific
253 application, you can say N to avoid the very slight overhead
257 bool "Collect kernel timers statistics"
258 depends on DEBUG_KERNEL && PROC_FS
260 If you say Y here, additional code will be inserted into the
261 timer routines to collect statistics about kernel timers being
262 reprogrammed. The statistics can be read from /proc/timer_stats.
263 The statistics collection is started by writing 1 to /proc/timer_stats,
264 writing 0 stops it. This feature is useful to collect information
265 about timer usage patterns in kernel and userspace. This feature
266 is lightweight if enabled in the kernel config but not activated
267 (it defaults to deactivated on bootup and will only be activated
268 if some application like powertop activates it explicitly).
271 bool "Debug object operations"
272 depends on DEBUG_KERNEL
274 If you say Y here, additional code will be inserted into the
275 kernel to track the life time of various objects and validate
276 the operations on those objects.
278 config DEBUG_OBJECTS_SELFTEST
279 bool "Debug objects selftest"
280 depends on DEBUG_OBJECTS
282 This enables the selftest of the object debug code.
284 config DEBUG_OBJECTS_FREE
285 bool "Debug objects in freed memory"
286 depends on DEBUG_OBJECTS
288 This enables checks whether a k/v free operation frees an area
289 which contains an object which has not been deactivated
290 properly. This can make kmalloc/kfree-intensive workloads
293 config DEBUG_OBJECTS_TIMERS
294 bool "Debug timer objects"
295 depends on DEBUG_OBJECTS
297 If you say Y here, additional code will be inserted into the
298 timer routines to track the life time of timer objects and
299 validate the timer operations.
301 config DEBUG_OBJECTS_WORK
302 bool "Debug work objects"
303 depends on DEBUG_OBJECTS
305 If you say Y here, additional code will be inserted into the
306 work queue routines to track the life time of work objects and
307 validate the work operations.
309 config DEBUG_OBJECTS_ENABLE_DEFAULT
310 int "debug_objects bootup default value (0-1)"
313 depends on DEBUG_OBJECTS
315 Debug objects boot parameter default value
318 bool "Debug slab memory allocations"
319 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
321 Say Y here to have the kernel do limited verification on memory
322 allocation as well as poisoning memory on free to catch use of freed
323 memory. This can make kmalloc/kfree-intensive workloads much slower.
325 config DEBUG_SLAB_LEAK
326 bool "Memory leak debugging"
327 depends on DEBUG_SLAB
330 bool "SLUB debugging on by default"
331 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
334 Boot with debugging on by default. SLUB boots by default with
335 the runtime debug capabilities switched off. Enabling this is
336 equivalent to specifying the "slub_debug" parameter on boot.
337 There is no support for more fine grained debug control like
338 possible with slub_debug=xxx. SLUB debugging may be switched
339 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
344 bool "Enable SLUB performance statistics"
345 depends on SLUB && SLUB_DEBUG && SYSFS
347 SLUB statistics are useful to debug SLUBs allocation behavior in
348 order find ways to optimize the allocator. This should never be
349 enabled for production use since keeping statistics slows down
350 the allocator by a few percentage points. The slabinfo command
351 supports the determination of the most active slabs to figure
352 out which slabs are relevant to a particular load.
353 Try running: slabinfo -DA
355 config DEBUG_KMEMLEAK
356 bool "Kernel memory leak detector"
357 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
358 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE)
360 select DEBUG_FS if SYSFS
361 select STACKTRACE if STACKTRACE_SUPPORT
365 Say Y here if you want to enable the memory leak
366 detector. The memory allocation/freeing is traced in a way
367 similar to the Boehm's conservative garbage collector, the
368 difference being that the orphan objects are not freed but
369 only shown in /sys/kernel/debug/kmemleak. Enabling this
370 feature will introduce an overhead to memory
371 allocations. See Documentation/kmemleak.txt for more
374 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
375 of finding leaks due to the slab objects poisoning.
377 In order to access the kmemleak file, debugfs needs to be
378 mounted (usually at /sys/kernel/debug).
380 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
381 int "Maximum kmemleak early log entries"
382 depends on DEBUG_KMEMLEAK
386 Kmemleak must track all the memory allocations to avoid
387 reporting false positives. Since memory may be allocated or
388 freed before kmemleak is initialised, an early log buffer is
389 used to store these actions. If kmemleak reports "early log
390 buffer exceeded", please increase this value.
392 config DEBUG_KMEMLEAK_TEST
393 tristate "Simple test for the kernel memory leak detector"
394 depends on DEBUG_KMEMLEAK
396 Say Y or M here to build a test for the kernel memory leak
397 detector. This option enables a module that explicitly leaks
403 bool "Debug preemptible kernel"
404 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
407 If you say Y here then the kernel will use a debug variant of the
408 commonly used smp_processor_id() function and will print warnings
409 if kernel code uses it in a preemption-unsafe way. Also, the kernel
410 will detect preemption count underflows.
412 config DEBUG_RT_MUTEXES
413 bool "RT Mutex debugging, deadlock detection"
414 depends on DEBUG_KERNEL && RT_MUTEXES
416 This allows rt mutex semantics violations and rt mutex related
417 deadlocks (lockups) to be detected and reported automatically.
422 depends on DEBUG_RT_MUTEXES
424 config RT_MUTEX_TESTER
425 bool "Built-in scriptable tester for rt-mutexes"
426 depends on DEBUG_KERNEL && RT_MUTEXES
428 This option enables a rt-mutex tester.
430 config DEBUG_SPINLOCK
431 bool "Spinlock and rw-lock debugging: basic checks"
432 depends on DEBUG_KERNEL
434 Say Y here and build SMP to catch missing spinlock initialization
435 and certain other kinds of spinlock errors commonly made. This is
436 best used in conjunction with the NMI watchdog so that spinlock
437 deadlocks are also debuggable.
440 bool "Mutex debugging: basic checks"
441 depends on DEBUG_KERNEL
443 This feature allows mutex semantics violations to be detected and
446 config DEBUG_LOCK_ALLOC
447 bool "Lock debugging: detect incorrect freeing of live locks"
448 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
449 select DEBUG_SPINLOCK
453 This feature will check whether any held lock (spinlock, rwlock,
454 mutex or rwsem) is incorrectly freed by the kernel, via any of the
455 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
456 vfree(), etc.), whether a live lock is incorrectly reinitialized via
457 spin_lock_init()/mutex_init()/etc., or whether there is any lock
458 held during task exit.
461 bool "Lock debugging: prove locking correctness"
462 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
464 select DEBUG_SPINLOCK
466 select DEBUG_LOCK_ALLOC
469 This feature enables the kernel to prove that all locking
470 that occurs in the kernel runtime is mathematically
471 correct: that under no circumstance could an arbitrary (and
472 not yet triggered) combination of observed locking
473 sequences (on an arbitrary number of CPUs, running an
474 arbitrary number of tasks and interrupt contexts) cause a
477 In short, this feature enables the kernel to report locking
478 related deadlocks before they actually occur.
480 The proof does not depend on how hard and complex a
481 deadlock scenario would be to trigger: how many
482 participant CPUs, tasks and irq-contexts would be needed
483 for it to trigger. The proof also does not depend on
484 timing: if a race and a resulting deadlock is possible
485 theoretically (no matter how unlikely the race scenario
486 is), it will be proven so and will immediately be
487 reported by the kernel (once the event is observed that
488 makes the deadlock theoretically possible).
490 If a deadlock is impossible (i.e. the locking rules, as
491 observed by the kernel, are mathematically correct), the
492 kernel reports nothing.
494 NOTE: this feature can also be enabled for rwlocks, mutexes
495 and rwsems - in which case all dependencies between these
496 different locking variants are observed and mapped too, and
497 the proof of observed correctness is also maintained for an
498 arbitrary combination of these separate locking variants.
500 For more details, see Documentation/lockdep-design.txt.
503 bool "RCU debugging: prove RCU correctness"
504 depends on PROVE_LOCKING
507 This feature enables lockdep extensions that check for correct
508 use of RCU APIs. This is currently under development. Say Y
509 if you want to debug RCU usage or help work on the PROVE_RCU
512 Say N if you are unsure.
514 config PROVE_RCU_REPEATEDLY
515 bool "RCU debugging: don't disable PROVE_RCU on first splat"
519 By itself, PROVE_RCU will disable checking upon issuing the
520 first warning (or "splat"). This feature prevents such
521 disabling, allowing multiple RCU-lockdep warnings to be printed
524 Say N if you are unsure.
528 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
530 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
535 bool "Lock usage statistics"
536 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
538 select DEBUG_SPINLOCK
540 select DEBUG_LOCK_ALLOC
543 This feature enables tracking lock contention points
545 For more details, see Documentation/lockstat.txt
547 This also enables lock events required by "perf lock",
549 If you want to use "perf lock", you also need to turn on
550 CONFIG_EVENT_TRACING.
552 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
553 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
556 bool "Lock dependency engine debugging"
557 depends on DEBUG_KERNEL && LOCKDEP
559 If you say Y here, the lock dependency engine will do
560 additional runtime checks to debug itself, at the price
561 of more runtime overhead.
563 config TRACE_IRQFLAGS
564 depends on DEBUG_KERNEL
567 depends on TRACE_IRQFLAGS_SUPPORT
568 depends on PROVE_LOCKING
570 config DEBUG_SPINLOCK_SLEEP
571 bool "Spinlock debugging: sleep-inside-spinlock checking"
572 depends on DEBUG_KERNEL
574 If you say Y here, various routines which may sleep will become very
575 noisy if they are called with a spinlock held.
577 config DEBUG_LOCKING_API_SELFTESTS
578 bool "Locking API boot-time self-tests"
579 depends on DEBUG_KERNEL
581 Say Y here if you want the kernel to run a short self-test during
582 bootup. The self-test checks whether common types of locking bugs
583 are detected by debugging mechanisms or not. (if you disable
584 lock debugging then those bugs wont be detected of course.)
585 The following locking APIs are covered: spinlocks, rwlocks,
590 depends on STACKTRACE_SUPPORT
593 bool "kobject debugging"
594 depends on DEBUG_KERNEL
596 If you say Y here, some extra kobject debugging messages will be sent
600 bool "Highmem debugging"
601 depends on DEBUG_KERNEL && HIGHMEM
603 This options enables addition error checking for high memory systems.
604 Disable for production systems.
606 config DEBUG_BUGVERBOSE
607 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
609 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
610 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
613 Say Y here to make BUG() panics output the file name and line number
614 of the BUG call as well as the EIP and oops trace. This aids
615 debugging but costs about 70-100K of memory.
618 bool "Compile the kernel with debug info"
619 depends on DEBUG_KERNEL
621 If you say Y here the resulting kernel image will include
622 debugging info resulting in a larger kernel image.
623 This adds debug symbols to the kernel and modules (gcc -g), and
624 is needed if you intend to use kernel crashdump or binary object
625 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
626 Say Y here only if you plan to debug the kernel.
632 depends on DEBUG_KERNEL
634 Enable this to turn on extended checks in the virtual-memory system
635 that may impact performance.
640 bool "Debug VM translations"
641 depends on DEBUG_KERNEL && X86
643 Enable some costly sanity checks in virtual to page code. This can
644 catch mistakes with virt_to_page() and friends.
648 config DEBUG_NOMMU_REGIONS
649 bool "Debug the global anon/private NOMMU mapping region tree"
650 depends on DEBUG_KERNEL && !MMU
652 This option causes the global tree of anonymous and private mapping
653 regions to be regularly checked for invalid topology.
655 config DEBUG_WRITECOUNT
656 bool "Debug filesystem writers count"
657 depends on DEBUG_KERNEL
659 Enable this to catch wrong use of the writers count in struct
660 vfsmount. This will increase the size of each file struct by
665 config DEBUG_MEMORY_INIT
666 bool "Debug memory initialisation" if EMBEDDED
669 Enable this for additional checks during memory initialisation.
670 The sanity checks verify aspects of the VM such as the memory model
671 and other information provided by the architecture. Verbose
672 information will be printed at KERN_DEBUG loglevel depending
673 on the mminit_loglevel= command-line option.
678 bool "Debug linked list manipulation"
679 depends on DEBUG_KERNEL
681 Enable this to turn on extended checks in the linked-list
687 bool "Debug SG table operations"
688 depends on DEBUG_KERNEL
690 Enable this to turn on checks on scatter-gather tables. This can
691 help find problems with drivers that do not properly initialize
696 config DEBUG_NOTIFIERS
697 bool "Debug notifier call chains"
698 depends on DEBUG_KERNEL
700 Enable this to turn on sanity checking for notifier call chains.
701 This is most useful for kernel developers to make sure that
702 modules properly unregister themselves from notifier chains.
703 This is a relatively cheap check but if you care about maximum
706 config DEBUG_CREDENTIALS
707 bool "Debug credential management"
708 depends on DEBUG_KERNEL
710 Enable this to turn on some debug checking for credential
711 management. The additional code keeps track of the number of
712 pointers from task_structs to any given cred struct, and checks to
713 see that this number never exceeds the usage count of the cred
716 Furthermore, if SELinux is enabled, this also checks that the
717 security pointer in the cred struct is never seen to be invalid.
722 # Select this config option from the architecture Kconfig, if it
723 # it is preferred to always offer frame pointers as a config
724 # option on the architecture (regardless of KERNEL_DEBUG):
726 config ARCH_WANT_FRAME_POINTERS
731 bool "Compile the kernel with frame pointers"
732 depends on DEBUG_KERNEL && \
733 (CRIS || M68K || M68KNOMMU || FRV || UML || \
734 AVR32 || SUPERH || BLACKFIN || MN10300) || \
735 ARCH_WANT_FRAME_POINTERS
736 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
738 If you say Y here the resulting kernel image will be slightly
739 larger and slower, but it gives very useful debugging information
740 in case of kernel bugs. (precise oopses/stacktraces/warnings)
742 config BOOT_PRINTK_DELAY
743 bool "Delay each boot printk message by N milliseconds"
744 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
746 This build option allows you to read kernel boot messages
747 by inserting a short delay after each one. The delay is
748 specified in milliseconds on the kernel command line,
749 using "boot_delay=N".
751 It is likely that you would also need to use "lpj=M" to preset
752 the "loops per jiffie" value.
753 See a previous boot log for the "lpj" value to use for your
754 system, and then set "lpj=M" before setting "boot_delay=N".
755 NOTE: Using this option may adversely affect SMP systems.
756 I.e., processors other than the first one may not boot up.
757 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
758 what it believes to be lockup conditions.
760 config RCU_TORTURE_TEST
761 tristate "torture tests for RCU"
762 depends on DEBUG_KERNEL
765 This option provides a kernel module that runs torture tests
766 on the RCU infrastructure. The kernel module may be built
767 after the fact on the running kernel to be tested, if desired.
769 Say Y here if you want RCU torture tests to be built into
771 Say M if you want the RCU torture tests to build as a module.
772 Say N if you are unsure.
774 config RCU_TORTURE_TEST_RUNNABLE
775 bool "torture tests for RCU runnable by default"
776 depends on RCU_TORTURE_TEST = y
779 This option provides a way to build the RCU torture tests
780 directly into the kernel without them starting up at boot
781 time. You can use /proc/sys/kernel/rcutorture_runnable
782 to manually override this setting. This /proc file is
783 available only when the RCU torture tests have been built
786 Say Y here if you want the RCU torture tests to start during
787 boot (you probably don't).
788 Say N here if you want the RCU torture tests to start only
789 after being manually enabled via /proc.
791 config RCU_CPU_STALL_DETECTOR
792 bool "Check for stalled CPUs delaying RCU grace periods"
793 depends on TREE_RCU || TREE_PREEMPT_RCU
796 This option causes RCU to printk information on which
797 CPUs are delaying the current grace period, but only when
798 the grace period extends for excessive time periods.
800 Say N if you want to disable such checks.
802 Say Y if you are unsure.
804 config RCU_CPU_STALL_VERBOSE
805 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
806 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
809 This option causes RCU to printk detailed per-task information
810 for any tasks that are stalling the current RCU grace period.
812 Say N if you are unsure.
814 Say Y if you want to enable such checks.
816 config KPROBES_SANITY_TEST
817 bool "Kprobes sanity tests"
818 depends on DEBUG_KERNEL
822 This option provides for testing basic kprobes functionality on
823 boot. A sample kprobe, jprobe and kretprobe are inserted and
824 verified for functionality.
826 Say N if you are unsure.
828 config BACKTRACE_SELF_TEST
829 tristate "Self test for the backtrace code"
830 depends on DEBUG_KERNEL
833 This option provides a kernel module that can be used to test
834 the kernel stack backtrace code. This option is not useful
835 for distributions or general kernels, but only for kernel
836 developers working on architecture code.
838 Note that if you want to also test saved backtraces, you will
839 have to enable STACKTRACE as well.
841 Say N if you are unsure.
843 config DEBUG_BLOCK_EXT_DEVT
844 bool "Force extended block device numbers and spread them"
845 depends on DEBUG_KERNEL
849 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
850 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
851 YOU ARE DOING. Distros, please enable this and fix whatever
854 Conventionally, block device numbers are allocated from
855 predetermined contiguous area. However, extended block area
856 may introduce non-contiguous block device numbers. This
857 option forces most block device numbers to be allocated from
858 the extended space and spreads them to discover kernel or
859 userland code paths which assume predetermined contiguous
860 device number allocation.
862 Note that turning on this debug option shuffles all the
863 device numbers for all IDE and SCSI devices including libata
864 ones, so root partition specified using device number
865 directly (via rdev or root=MAJ:MIN) won't work anymore.
866 Textual device names (root=/dev/sdXn) will continue to work.
868 Say N if you are unsure.
870 config DEBUG_FORCE_WEAK_PER_CPU
871 bool "Force weak per-cpu definitions"
872 depends on DEBUG_KERNEL
874 s390 and alpha require percpu variables in modules to be
875 defined weak to work around addressing range issue which
876 puts the following two restrictions on percpu variable
879 1. percpu symbols must be unique whether static or not
880 2. percpu variables can't be defined inside a function
882 To ensure that generic code follows the above rules, this
883 option forces all percpu variables to be defined as weak.
886 tristate "Linux Kernel Dump Test Tool Module"
891 This module enables testing of the different dumping mechanisms by
892 inducing system failures at predefined crash points.
893 If you don't need it: say N
894 Choose M here to compile this code as a module. The module will be
897 Documentation on how to use the module can be found in
898 Documentation/fault-injection/provoke-crashes.txt
900 config CPU_NOTIFIER_ERROR_INJECT
901 tristate "CPU notifier error injection module"
902 depends on HOTPLUG_CPU && DEBUG_KERNEL
904 This option provides a kernel module that can be used to test
905 the error handling of the cpu notifiers
907 To compile this code as a module, choose M here: the module will
908 be called cpu-notifier-error-inject.
912 config FAULT_INJECTION
913 bool "Fault-injection framework"
914 depends on DEBUG_KERNEL
916 Provide fault-injection framework.
917 For more details, see Documentation/fault-injection/.
920 bool "Fault-injection capability for kmalloc"
921 depends on FAULT_INJECTION
922 depends on SLAB || SLUB
924 Provide fault-injection capability for kmalloc.
926 config FAIL_PAGE_ALLOC
927 bool "Fault-injection capabilitiy for alloc_pages()"
928 depends on FAULT_INJECTION
930 Provide fault-injection capability for alloc_pages().
932 config FAIL_MAKE_REQUEST
933 bool "Fault-injection capability for disk IO"
934 depends on FAULT_INJECTION && BLOCK
936 Provide fault-injection capability for disk IO.
938 config FAIL_IO_TIMEOUT
939 bool "Fault-injection capability for faking disk interrupts"
940 depends on FAULT_INJECTION && BLOCK
942 Provide fault-injection capability on end IO handling. This
943 will make the block layer "forget" an interrupt as configured,
944 thus exercising the error handling.
946 Only works with drivers that use the generic timeout handling,
947 for others it wont do anything.
949 config FAULT_INJECTION_DEBUG_FS
950 bool "Debugfs entries for fault-injection capabilities"
951 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
953 Enable configuration of fault-injection capabilities via debugfs.
955 config FAULT_INJECTION_STACKTRACE_FILTER
956 bool "stacktrace filter for fault-injection capabilities"
957 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
960 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE
962 Provide stacktrace filter for fault-injection capabilities
965 bool "Latency measuring infrastructure"
966 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE
972 depends on HAVE_LATENCYTOP_SUPPORT
974 Enable this option if you want to use the LatencyTOP tool
975 to find out which userspace is blocking on what kernel operations.
977 config SYSCTL_SYSCALL_CHECK
981 sys_sysctl uses binary paths that have been found challenging
982 to properly maintain and use. This enables checks that help
983 you to keep things correct.
985 source mm/Kconfig.debug
986 source kernel/trace/Kconfig
988 config PROVIDE_OHCI1394_DMA_INIT
989 bool "Remote debugging over FireWire early on boot"
990 depends on PCI && X86
992 If you want to debug problems which hang or crash the kernel early
993 on boot and the crashing machine has a FireWire port, you can use
994 this feature to remotely access the memory of the crashed machine
995 over FireWire. This employs remote DMA as part of the OHCI1394
996 specification which is now the standard for FireWire controllers.
998 With remote DMA, you can monitor the printk buffer remotely using
999 firescope and access all memory below 4GB using fireproxy from gdb.
1000 Even controlling a kernel debugger is possible using remote DMA.
1004 If ohci1394_dma=early is used as boot parameter, it will initialize
1005 all OHCI1394 controllers which are found in the PCI config space.
1007 As all changes to the FireWire bus such as enabling and disabling
1008 devices cause a bus reset and thereby disable remote DMA for all
1009 devices, be sure to have the cable plugged and FireWire enabled on
1010 the debugging host before booting the debug target for debugging.
1012 This code (~1k) is freed after boot. By then, the firewire stack
1013 in charge of the OHCI-1394 controllers should be used instead.
1015 See Documentation/debugging-via-ohci1394.txt for more information.
1017 config FIREWIRE_OHCI_REMOTE_DMA
1018 bool "Remote debugging over FireWire with firewire-ohci"
1019 depends on FIREWIRE_OHCI
1021 This option lets you use the FireWire bus for remote debugging
1022 with help of the firewire-ohci driver. It enables unfiltered
1023 remote DMA in firewire-ohci.
1024 See Documentation/debugging-via-ohci1394.txt for more information.
1029 bool "Build targets in Documentation/ tree"
1030 depends on HEADERS_CHECK
1032 This option attempts to build objects from the source files in the
1033 kernel Documentation/ tree.
1035 Say N if you are unsure.
1037 config DYNAMIC_DEBUG
1038 bool "Enable dynamic printk() support"
1044 Compiles debug level messages into the kernel, which would not
1045 otherwise be available at runtime. These messages can then be
1046 enabled/disabled based on various levels of scope - per source file,
1047 function, module, format string, and line number. This mechanism
1048 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1049 this compile option is a larger kernel text size of about 2%.
1053 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1054 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1055 filesystem must first be mounted before making use of this feature.
1056 We refer the control file as: <debugfs>/dynamic_debug/control. This
1057 file contains a list of the debug statements that can be enabled. The
1058 format for each line of the file is:
1060 filename:lineno [module]function flags format
1062 filename : source file of the debug statement
1063 lineno : line number of the debug statement
1064 module : module that contains the debug statement
1065 function : function that contains the debug statement
1066 flags : 'p' means the line is turned 'on' for printing
1067 format : the format used for the debug statement
1071 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1072 # filename:lineno [module]function flags format
1073 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1074 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1075 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1079 // enable the message at line 1603 of file svcsock.c
1080 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1081 <debugfs>/dynamic_debug/control
1083 // enable all the messages in file svcsock.c
1084 nullarbor:~ # echo -n 'file svcsock.c +p' >
1085 <debugfs>/dynamic_debug/control
1087 // enable all the messages in the NFS server module
1088 nullarbor:~ # echo -n 'module nfsd +p' >
1089 <debugfs>/dynamic_debug/control
1091 // enable all 12 messages in the function svc_process()
1092 nullarbor:~ # echo -n 'func svc_process +p' >
1093 <debugfs>/dynamic_debug/control
1095 // disable all 12 messages in the function svc_process()
1096 nullarbor:~ # echo -n 'func svc_process -p' >
1097 <debugfs>/dynamic_debug/control
1099 See Documentation/dynamic-debug-howto.txt for additional information.
1101 config DMA_API_DEBUG
1102 bool "Enable debugging of DMA-API usage"
1103 depends on HAVE_DMA_API_DEBUG
1105 Enable this option to debug the use of the DMA API by device drivers.
1106 With this option you will be able to detect common bugs in device
1107 drivers like double-freeing of DMA mappings or freeing mappings that
1108 were never allocated.
1109 This option causes a performance degredation. Use only if you want
1110 to debug device drivers. If unsure, say N.
1112 config ATOMIC64_SELFTEST
1113 bool "Perform an atomic64_t self-test at boot"
1115 Enable this option to test the atomic64_t functions at boot.
1119 source "samples/Kconfig"
1121 source "lib/Kconfig.kgdb"
1123 source "lib/Kconfig.kmemcheck"