3 bool "Show timing information on printks"
6 Selecting this option causes timing information to be
7 included in printk output. This allows you to measure
8 the interval between kernel operations, including bootup
9 operations. This is useful for identifying long delays
12 config ENABLE_WARN_DEPRECATED
13 bool "Enable __deprecated logic"
16 Enable the __deprecated logic in the kernel build.
17 Disable this to suppress the "warning: 'foo' is deprecated
18 (declared at kernel/power/somefile.c:1234)" messages.
20 config ENABLE_MUST_CHECK
21 bool "Enable __must_check logic"
24 Enable the __must_check logic in the kernel build. Disable this to
25 suppress the "warning: ignoring return value of 'foo', declared with
26 attribute warn_unused_result" messages.
29 int "Warn for stack frames larger than (needs gcc 4.4)"
31 default 1024 if !64BIT
34 Tell gcc to warn at build time for stack frames larger than this.
35 Setting this too low will cause a lot of warnings.
36 Setting it to 0 disables the warning.
40 bool "Magic SysRq key"
43 If you say Y here, you will have some control over the system even
44 if the system crashes for example during kernel debugging (e.g., you
45 will be able to flush the buffer cache to disk, reboot the system
46 immediately or dump some status information). This is accomplished
47 by pressing various keys while holding SysRq (Alt+PrintScreen). It
48 also works on a serial console (on PC hardware at least), if you
49 send a BREAK and then within 5 seconds a command keypress. The
50 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
51 unless you really know what this hack does.
54 bool "Strip assembler-generated symbols during link"
57 Strip internal assembler-generated symbols during a link (symbols
58 that look like '.Lxxx') so they don't pollute the output of
59 get_wchan() and suchlike.
62 bool "Enable unused/obsolete exported symbols"
65 Unused but exported symbols make the kernel needlessly bigger. For
66 that reason most of these unused exports will soon be removed. This
67 option is provided temporarily to provide a transition period in case
68 some external kernel module needs one of these symbols anyway. If you
69 encounter such a case in your module, consider if you are actually
70 using the right API. (rationale: since nobody in the kernel is using
71 this in a module, there is a pretty good chance it's actually the
72 wrong interface to use). If you really need the symbol, please send a
73 mail to the linux kernel mailing list mentioning the symbol and why
74 you really need it, and what the merge plan to the mainline kernel for
78 bool "Debug Filesystem"
81 debugfs is a virtual file system that kernel developers use to put
82 debugging files into. Enable this option to be able to read and
85 For detailed documentation on the debugfs API, see
86 Documentation/DocBook/filesystems.
91 bool "Run 'make headers_check' when building vmlinux"
94 This option will extract the user-visible kernel headers whenever
95 building the kernel, and will run basic sanity checks on them to
96 ensure that exported files do not attempt to include files which
97 were not exported, etc.
99 If you're making modifications to header files which are
100 relevant for userspace, say 'Y', and check the headers
101 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
102 your build tree), to make sure they're suitable.
104 config DEBUG_SECTION_MISMATCH
105 bool "Enable full Section mismatch analysis"
106 depends on UNDEFINED || (BLACKFIN)
108 # This option is on purpose disabled for now.
109 # It will be enabled when we are down to a reasonable number
110 # of section mismatch warnings (< 10 for an allyesconfig build)
112 The section mismatch analysis checks if there are illegal
113 references from one section to another section.
114 Linux will during link or during runtime drop some sections
115 and any use of code/data previously in these sections will
116 most likely result in an oops.
117 In the code functions and variables are annotated with
118 __init, __devinit etc. (see full list in include/linux/init.h)
119 which results in the code/data being placed in specific sections.
120 The section mismatch analysis is always done after a full
121 kernel build but enabling this option will in addition
123 - Add the option -fno-inline-functions-called-once to gcc
124 When inlining a function annotated __init in a non-init
125 function we would lose the section information and thus
126 the analysis would not catch the illegal reference.
127 This option tells gcc to inline less but will also
128 result in a larger kernel.
129 - Run the section mismatch analysis for each module/built-in.o
130 When we run the section mismatch analysis on vmlinux.o we
131 lose valueble information about where the mismatch was
133 Running the analysis for each module/built-in.o file
134 will tell where the mismatch happens much closer to the
135 source. The drawback is that we will report the same
136 mismatch at least twice.
137 - Enable verbose reporting from modpost to help solving
138 the section mismatches reported.
141 bool "Kernel debugging"
143 Say Y here if you are developing drivers or trying to debug and
144 identify kernel problems.
147 bool "Debug shared IRQ handlers"
148 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
150 Enable this to generate a spurious interrupt as soon as a shared
151 interrupt handler is registered, and just before one is deregistered.
152 Drivers ought to be able to handle interrupts coming in at those
153 points; some don't and need to be caught.
155 config DETECT_SOFTLOCKUP
157 depends on DEBUG_KERNEL && !S390
160 Say Y here to enable the kernel to detect "soft lockups",
161 which are bugs that cause the kernel to loop in kernel
162 mode for more than 60 seconds, without giving other tasks a
165 When a soft-lockup is detected, the kernel will print the
166 current stack trace (which you should report), but the
167 system will stay locked up. This feature has negligible
170 (Note that "hard lockups" are separate type of bugs that
171 can be detected via the NMI-watchdog, on platforms that
174 config LOCKUP_DETECTOR
175 bool "Detect Hard and Soft Lockups"
176 depends on DEBUG_KERNEL
177 default DETECT_SOFTLOCKUP
179 Say Y here to enable the kernel to act as a watchdog to detect
180 hard and soft lockups.
182 Softlockups are bugs that cause the kernel to loop in kernel
183 mode for more than 60 seconds, without giving other tasks a
184 chance to run. The current stack trace is displayed upon
185 detection and the system will stay locked up.
187 Hardlockups are bugs that cause the CPU to loop in kernel mode
188 for more than 60 seconds, without letting other interrupts have a
189 chance to run. The current stack trace is displayed upon detection
190 and the system will stay locked up.
192 The overhead should be minimal. A periodic hrtimer runs to
193 generate interrupts and kick the watchdog task every 10-12 seconds.
194 An NMI is generated every 60 seconds or so to check for hardlockups.
196 config BOOTPARAM_SOFTLOCKUP_PANIC
197 bool "Panic (Reboot) On Soft Lockups"
198 depends on DETECT_SOFTLOCKUP
200 Say Y here to enable the kernel to panic on "soft lockups",
201 which are bugs that cause the kernel to loop in kernel
202 mode for more than 60 seconds, without giving other tasks a
205 The panic can be used in combination with panic_timeout,
206 to cause the system to reboot automatically after a
207 lockup has been detected. This feature is useful for
208 high-availability systems that have uptime guarantees and
209 where a lockup must be resolved ASAP.
213 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
215 depends on DETECT_SOFTLOCKUP
217 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
218 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
220 config DETECT_HUNG_TASK
221 bool "Detect Hung Tasks"
222 depends on DEBUG_KERNEL
223 default DETECT_SOFTLOCKUP
225 Say Y here to enable the kernel to detect "hung tasks",
226 which are bugs that cause the task to be stuck in
227 uninterruptible "D" state indefinitiley.
229 When a hung task is detected, the kernel will print the
230 current stack trace (which you should report), but the
231 task will stay in uninterruptible state. If lockdep is
232 enabled then all held locks will also be reported. This
233 feature has negligible overhead.
235 config BOOTPARAM_HUNG_TASK_PANIC
236 bool "Panic (Reboot) On Hung Tasks"
237 depends on DETECT_HUNG_TASK
239 Say Y here to enable the kernel to panic on "hung tasks",
240 which are bugs that cause the kernel to leave a task stuck
241 in uninterruptible "D" state.
243 The panic can be used in combination with panic_timeout,
244 to cause the system to reboot automatically after a
245 hung task has been detected. This feature is useful for
246 high-availability systems that have uptime guarantees and
247 where a hung tasks must be resolved ASAP.
251 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
253 depends on DETECT_HUNG_TASK
255 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
256 default 1 if BOOTPARAM_HUNG_TASK_PANIC
259 bool "Collect scheduler debugging info"
260 depends on DEBUG_KERNEL && PROC_FS
263 If you say Y here, the /proc/sched_debug file will be provided
264 that can help debug the scheduler. The runtime overhead of this
268 bool "Collect scheduler statistics"
269 depends on DEBUG_KERNEL && PROC_FS
271 If you say Y here, additional code will be inserted into the
272 scheduler and related routines to collect statistics about
273 scheduler behavior and provide them in /proc/schedstat. These
274 stats may be useful for both tuning and debugging the scheduler
275 If you aren't debugging the scheduler or trying to tune a specific
276 application, you can say N to avoid the very slight overhead
280 bool "Collect kernel timers statistics"
281 depends on DEBUG_KERNEL && PROC_FS
283 If you say Y here, additional code will be inserted into the
284 timer routines to collect statistics about kernel timers being
285 reprogrammed. The statistics can be read from /proc/timer_stats.
286 The statistics collection is started by writing 1 to /proc/timer_stats,
287 writing 0 stops it. This feature is useful to collect information
288 about timer usage patterns in kernel and userspace. This feature
289 is lightweight if enabled in the kernel config but not activated
290 (it defaults to deactivated on bootup and will only be activated
291 if some application like powertop activates it explicitly).
294 bool "Debug object operations"
295 depends on DEBUG_KERNEL
297 If you say Y here, additional code will be inserted into the
298 kernel to track the life time of various objects and validate
299 the operations on those objects.
301 config DEBUG_OBJECTS_SELFTEST
302 bool "Debug objects selftest"
303 depends on DEBUG_OBJECTS
305 This enables the selftest of the object debug code.
307 config DEBUG_OBJECTS_FREE
308 bool "Debug objects in freed memory"
309 depends on DEBUG_OBJECTS
311 This enables checks whether a k/v free operation frees an area
312 which contains an object which has not been deactivated
313 properly. This can make kmalloc/kfree-intensive workloads
316 config DEBUG_OBJECTS_TIMERS
317 bool "Debug timer objects"
318 depends on DEBUG_OBJECTS
320 If you say Y here, additional code will be inserted into the
321 timer routines to track the life time of timer objects and
322 validate the timer operations.
324 config DEBUG_OBJECTS_WORK
325 bool "Debug work objects"
326 depends on DEBUG_OBJECTS
328 If you say Y here, additional code will be inserted into the
329 work queue routines to track the life time of work objects and
330 validate the work operations.
332 config DEBUG_OBJECTS_ENABLE_DEFAULT
333 int "debug_objects bootup default value (0-1)"
336 depends on DEBUG_OBJECTS
338 Debug objects boot parameter default value
341 bool "Debug slab memory allocations"
342 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
344 Say Y here to have the kernel do limited verification on memory
345 allocation as well as poisoning memory on free to catch use of freed
346 memory. This can make kmalloc/kfree-intensive workloads much slower.
348 config DEBUG_SLAB_LEAK
349 bool "Memory leak debugging"
350 depends on DEBUG_SLAB
353 bool "SLUB debugging on by default"
354 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
357 Boot with debugging on by default. SLUB boots by default with
358 the runtime debug capabilities switched off. Enabling this is
359 equivalent to specifying the "slub_debug" parameter on boot.
360 There is no support for more fine grained debug control like
361 possible with slub_debug=xxx. SLUB debugging may be switched
362 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
367 bool "Enable SLUB performance statistics"
368 depends on SLUB && SLUB_DEBUG && SYSFS
370 SLUB statistics are useful to debug SLUBs allocation behavior in
371 order find ways to optimize the allocator. This should never be
372 enabled for production use since keeping statistics slows down
373 the allocator by a few percentage points. The slabinfo command
374 supports the determination of the most active slabs to figure
375 out which slabs are relevant to a particular load.
376 Try running: slabinfo -DA
378 config DEBUG_KMEMLEAK
379 bool "Kernel memory leak detector"
380 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
381 (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE)
383 select DEBUG_FS if SYSFS
384 select STACKTRACE if STACKTRACE_SUPPORT
388 Say Y here if you want to enable the memory leak
389 detector. The memory allocation/freeing is traced in a way
390 similar to the Boehm's conservative garbage collector, the
391 difference being that the orphan objects are not freed but
392 only shown in /sys/kernel/debug/kmemleak. Enabling this
393 feature will introduce an overhead to memory
394 allocations. See Documentation/kmemleak.txt for more
397 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
398 of finding leaks due to the slab objects poisoning.
400 In order to access the kmemleak file, debugfs needs to be
401 mounted (usually at /sys/kernel/debug).
403 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
404 int "Maximum kmemleak early log entries"
405 depends on DEBUG_KMEMLEAK
409 Kmemleak must track all the memory allocations to avoid
410 reporting false positives. Since memory may be allocated or
411 freed before kmemleak is initialised, an early log buffer is
412 used to store these actions. If kmemleak reports "early log
413 buffer exceeded", please increase this value.
415 config DEBUG_KMEMLEAK_TEST
416 tristate "Simple test for the kernel memory leak detector"
417 depends on DEBUG_KMEMLEAK
419 Say Y or M here to build a test for the kernel memory leak
420 detector. This option enables a module that explicitly leaks
426 bool "Debug preemptible kernel"
427 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
430 If you say Y here then the kernel will use a debug variant of the
431 commonly used smp_processor_id() function and will print warnings
432 if kernel code uses it in a preemption-unsafe way. Also, the kernel
433 will detect preemption count underflows.
435 config DEBUG_RT_MUTEXES
436 bool "RT Mutex debugging, deadlock detection"
437 depends on DEBUG_KERNEL && RT_MUTEXES
439 This allows rt mutex semantics violations and rt mutex related
440 deadlocks (lockups) to be detected and reported automatically.
445 depends on DEBUG_RT_MUTEXES
447 config RT_MUTEX_TESTER
448 bool "Built-in scriptable tester for rt-mutexes"
449 depends on DEBUG_KERNEL && RT_MUTEXES
451 This option enables a rt-mutex tester.
453 config DEBUG_SPINLOCK
454 bool "Spinlock and rw-lock debugging: basic checks"
455 depends on DEBUG_KERNEL
457 Say Y here and build SMP to catch missing spinlock initialization
458 and certain other kinds of spinlock errors commonly made. This is
459 best used in conjunction with the NMI watchdog so that spinlock
460 deadlocks are also debuggable.
463 bool "Mutex debugging: basic checks"
464 depends on DEBUG_KERNEL
466 This feature allows mutex semantics violations to be detected and
469 config DEBUG_LOCK_ALLOC
470 bool "Lock debugging: detect incorrect freeing of live locks"
471 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
472 select DEBUG_SPINLOCK
476 This feature will check whether any held lock (spinlock, rwlock,
477 mutex or rwsem) is incorrectly freed by the kernel, via any of the
478 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
479 vfree(), etc.), whether a live lock is incorrectly reinitialized via
480 spin_lock_init()/mutex_init()/etc., or whether there is any lock
481 held during task exit.
484 bool "Lock debugging: prove locking correctness"
485 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
487 select DEBUG_SPINLOCK
489 select DEBUG_LOCK_ALLOC
492 This feature enables the kernel to prove that all locking
493 that occurs in the kernel runtime is mathematically
494 correct: that under no circumstance could an arbitrary (and
495 not yet triggered) combination of observed locking
496 sequences (on an arbitrary number of CPUs, running an
497 arbitrary number of tasks and interrupt contexts) cause a
500 In short, this feature enables the kernel to report locking
501 related deadlocks before they actually occur.
503 The proof does not depend on how hard and complex a
504 deadlock scenario would be to trigger: how many
505 participant CPUs, tasks and irq-contexts would be needed
506 for it to trigger. The proof also does not depend on
507 timing: if a race and a resulting deadlock is possible
508 theoretically (no matter how unlikely the race scenario
509 is), it will be proven so and will immediately be
510 reported by the kernel (once the event is observed that
511 makes the deadlock theoretically possible).
513 If a deadlock is impossible (i.e. the locking rules, as
514 observed by the kernel, are mathematically correct), the
515 kernel reports nothing.
517 NOTE: this feature can also be enabled for rwlocks, mutexes
518 and rwsems - in which case all dependencies between these
519 different locking variants are observed and mapped too, and
520 the proof of observed correctness is also maintained for an
521 arbitrary combination of these separate locking variants.
523 For more details, see Documentation/lockdep-design.txt.
526 bool "RCU debugging: prove RCU correctness"
527 depends on PROVE_LOCKING
530 This feature enables lockdep extensions that check for correct
531 use of RCU APIs. This is currently under development. Say Y
532 if you want to debug RCU usage or help work on the PROVE_RCU
535 Say N if you are unsure.
539 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
541 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
546 bool "Lock usage statistics"
547 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
549 select DEBUG_SPINLOCK
551 select DEBUG_LOCK_ALLOC
554 This feature enables tracking lock contention points
556 For more details, see Documentation/lockstat.txt
558 This also enables lock events required by "perf lock",
560 If you want to use "perf lock", you also need to turn on
561 CONFIG_EVENT_TRACING.
563 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
564 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
567 bool "Lock dependency engine debugging"
568 depends on DEBUG_KERNEL && LOCKDEP
570 If you say Y here, the lock dependency engine will do
571 additional runtime checks to debug itself, at the price
572 of more runtime overhead.
574 config TRACE_IRQFLAGS
575 depends on DEBUG_KERNEL
578 depends on TRACE_IRQFLAGS_SUPPORT
579 depends on PROVE_LOCKING
581 config DEBUG_SPINLOCK_SLEEP
582 bool "Spinlock debugging: sleep-inside-spinlock checking"
583 depends on DEBUG_KERNEL
585 If you say Y here, various routines which may sleep will become very
586 noisy if they are called with a spinlock held.
588 config DEBUG_LOCKING_API_SELFTESTS
589 bool "Locking API boot-time self-tests"
590 depends on DEBUG_KERNEL
592 Say Y here if you want the kernel to run a short self-test during
593 bootup. The self-test checks whether common types of locking bugs
594 are detected by debugging mechanisms or not. (if you disable
595 lock debugging then those bugs wont be detected of course.)
596 The following locking APIs are covered: spinlocks, rwlocks,
601 depends on STACKTRACE_SUPPORT
604 bool "kobject debugging"
605 depends on DEBUG_KERNEL
607 If you say Y here, some extra kobject debugging messages will be sent
611 bool "Highmem debugging"
612 depends on DEBUG_KERNEL && HIGHMEM
614 This options enables addition error checking for high memory systems.
615 Disable for production systems.
617 config DEBUG_BUGVERBOSE
618 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
620 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
621 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
624 Say Y here to make BUG() panics output the file name and line number
625 of the BUG call as well as the EIP and oops trace. This aids
626 debugging but costs about 70-100K of memory.
629 bool "Compile the kernel with debug info"
630 depends on DEBUG_KERNEL
632 If you say Y here the resulting kernel image will include
633 debugging info resulting in a larger kernel image.
634 This adds debug symbols to the kernel and modules (gcc -g), and
635 is needed if you intend to use kernel crashdump or binary object
636 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
637 Say Y here only if you plan to debug the kernel.
643 depends on DEBUG_KERNEL
645 Enable this to turn on extended checks in the virtual-memory system
646 that may impact performance.
651 bool "Debug VM translations"
652 depends on DEBUG_KERNEL && X86
654 Enable some costly sanity checks in virtual to page code. This can
655 catch mistakes with virt_to_page() and friends.
659 config DEBUG_NOMMU_REGIONS
660 bool "Debug the global anon/private NOMMU mapping region tree"
661 depends on DEBUG_KERNEL && !MMU
663 This option causes the global tree of anonymous and private mapping
664 regions to be regularly checked for invalid topology.
666 config DEBUG_WRITECOUNT
667 bool "Debug filesystem writers count"
668 depends on DEBUG_KERNEL
670 Enable this to catch wrong use of the writers count in struct
671 vfsmount. This will increase the size of each file struct by
676 config DEBUG_MEMORY_INIT
677 bool "Debug memory initialisation" if EMBEDDED
680 Enable this for additional checks during memory initialisation.
681 The sanity checks verify aspects of the VM such as the memory model
682 and other information provided by the architecture. Verbose
683 information will be printed at KERN_DEBUG loglevel depending
684 on the mminit_loglevel= command-line option.
689 bool "Debug linked list manipulation"
690 depends on DEBUG_KERNEL
692 Enable this to turn on extended checks in the linked-list
698 bool "Debug SG table operations"
699 depends on DEBUG_KERNEL
701 Enable this to turn on checks on scatter-gather tables. This can
702 help find problems with drivers that do not properly initialize
707 config DEBUG_NOTIFIERS
708 bool "Debug notifier call chains"
709 depends on DEBUG_KERNEL
711 Enable this to turn on sanity checking for notifier call chains.
712 This is most useful for kernel developers to make sure that
713 modules properly unregister themselves from notifier chains.
714 This is a relatively cheap check but if you care about maximum
717 config DEBUG_CREDENTIALS
718 bool "Debug credential management"
719 depends on DEBUG_KERNEL
721 Enable this to turn on some debug checking for credential
722 management. The additional code keeps track of the number of
723 pointers from task_structs to any given cred struct, and checks to
724 see that this number never exceeds the usage count of the cred
727 Furthermore, if SELinux is enabled, this also checks that the
728 security pointer in the cred struct is never seen to be invalid.
733 # Select this config option from the architecture Kconfig, if it
734 # it is preferred to always offer frame pointers as a config
735 # option on the architecture (regardless of KERNEL_DEBUG):
737 config ARCH_WANT_FRAME_POINTERS
742 bool "Compile the kernel with frame pointers"
743 depends on DEBUG_KERNEL && \
744 (CRIS || M68K || M68KNOMMU || FRV || UML || \
745 AVR32 || SUPERH || BLACKFIN || MN10300) || \
746 ARCH_WANT_FRAME_POINTERS
747 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
749 If you say Y here the resulting kernel image will be slightly
750 larger and slower, but it gives very useful debugging information
751 in case of kernel bugs. (precise oopses/stacktraces/warnings)
753 config BOOT_PRINTK_DELAY
754 bool "Delay each boot printk message by N milliseconds"
755 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
757 This build option allows you to read kernel boot messages
758 by inserting a short delay after each one. The delay is
759 specified in milliseconds on the kernel command line,
760 using "boot_delay=N".
762 It is likely that you would also need to use "lpj=M" to preset
763 the "loops per jiffie" value.
764 See a previous boot log for the "lpj" value to use for your
765 system, and then set "lpj=M" before setting "boot_delay=N".
766 NOTE: Using this option may adversely affect SMP systems.
767 I.e., processors other than the first one may not boot up.
768 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
769 what it believes to be lockup conditions.
771 config RCU_TORTURE_TEST
772 tristate "torture tests for RCU"
773 depends on DEBUG_KERNEL
776 This option provides a kernel module that runs torture tests
777 on the RCU infrastructure. The kernel module may be built
778 after the fact on the running kernel to be tested, if desired.
780 Say Y here if you want RCU torture tests to be built into
782 Say M if you want the RCU torture tests to build as a module.
783 Say N if you are unsure.
785 config RCU_TORTURE_TEST_RUNNABLE
786 bool "torture tests for RCU runnable by default"
787 depends on RCU_TORTURE_TEST = y
790 This option provides a way to build the RCU torture tests
791 directly into the kernel without them starting up at boot
792 time. You can use /proc/sys/kernel/rcutorture_runnable
793 to manually override this setting. This /proc file is
794 available only when the RCU torture tests have been built
797 Say Y here if you want the RCU torture tests to start during
798 boot (you probably don't).
799 Say N here if you want the RCU torture tests to start only
800 after being manually enabled via /proc.
802 config RCU_CPU_STALL_DETECTOR
803 bool "Check for stalled CPUs delaying RCU grace periods"
804 depends on TREE_RCU || TREE_PREEMPT_RCU
807 This option causes RCU to printk information on which
808 CPUs are delaying the current grace period, but only when
809 the grace period extends for excessive time periods.
811 Say N if you want to disable such checks.
813 Say Y if you are unsure.
815 config RCU_CPU_STALL_VERBOSE
816 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
817 depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
820 This option causes RCU to printk detailed per-task information
821 for any tasks that are stalling the current RCU grace period.
823 Say N if you are unsure.
825 Say Y if you want to enable such checks.
827 config KPROBES_SANITY_TEST
828 bool "Kprobes sanity tests"
829 depends on DEBUG_KERNEL
833 This option provides for testing basic kprobes functionality on
834 boot. A sample kprobe, jprobe and kretprobe are inserted and
835 verified for functionality.
837 Say N if you are unsure.
839 config BACKTRACE_SELF_TEST
840 tristate "Self test for the backtrace code"
841 depends on DEBUG_KERNEL
844 This option provides a kernel module that can be used to test
845 the kernel stack backtrace code. This option is not useful
846 for distributions or general kernels, but only for kernel
847 developers working on architecture code.
849 Note that if you want to also test saved backtraces, you will
850 have to enable STACKTRACE as well.
852 Say N if you are unsure.
854 config DEBUG_BLOCK_EXT_DEVT
855 bool "Force extended block device numbers and spread them"
856 depends on DEBUG_KERNEL
860 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
861 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
862 YOU ARE DOING. Distros, please enable this and fix whatever
865 Conventionally, block device numbers are allocated from
866 predetermined contiguous area. However, extended block area
867 may introduce non-contiguous block device numbers. This
868 option forces most block device numbers to be allocated from
869 the extended space and spreads them to discover kernel or
870 userland code paths which assume predetermined contiguous
871 device number allocation.
873 Note that turning on this debug option shuffles all the
874 device numbers for all IDE and SCSI devices including libata
875 ones, so root partition specified using device number
876 directly (via rdev or root=MAJ:MIN) won't work anymore.
877 Textual device names (root=/dev/sdXn) will continue to work.
879 Say N if you are unsure.
881 config DEBUG_FORCE_WEAK_PER_CPU
882 bool "Force weak per-cpu definitions"
883 depends on DEBUG_KERNEL
885 s390 and alpha require percpu variables in modules to be
886 defined weak to work around addressing range issue which
887 puts the following two restrictions on percpu variable
890 1. percpu symbols must be unique whether static or not
891 2. percpu variables can't be defined inside a function
893 To ensure that generic code follows the above rules, this
894 option forces all percpu variables to be defined as weak.
897 tristate "Linux Kernel Dump Test Tool Module"
902 This module enables testing of the different dumping mechanisms by
903 inducing system failures at predefined crash points.
904 If you don't need it: say N
905 Choose M here to compile this code as a module. The module will be
908 Documentation on how to use the module can be found in
909 Documentation/fault-injection/provoke-crashes.txt
911 config FAULT_INJECTION
912 bool "Fault-injection framework"
913 depends on DEBUG_KERNEL
915 Provide fault-injection framework.
916 For more details, see Documentation/fault-injection/.
919 bool "Fault-injection capability for kmalloc"
920 depends on FAULT_INJECTION
921 depends on SLAB || SLUB
923 Provide fault-injection capability for kmalloc.
925 config FAIL_PAGE_ALLOC
926 bool "Fault-injection capabilitiy for alloc_pages()"
927 depends on FAULT_INJECTION
929 Provide fault-injection capability for alloc_pages().
931 config FAIL_MAKE_REQUEST
932 bool "Fault-injection capability for disk IO"
933 depends on FAULT_INJECTION && BLOCK
935 Provide fault-injection capability for disk IO.
937 config FAIL_IO_TIMEOUT
938 bool "Faul-injection capability for faking disk interrupts"
939 depends on FAULT_INJECTION && BLOCK
941 Provide fault-injection capability on end IO handling. This
942 will make the block layer "forget" an interrupt as configured,
943 thus exercising the error handling.
945 Only works with drivers that use the generic timeout handling,
946 for others it wont do anything.
948 config FAULT_INJECTION_DEBUG_FS
949 bool "Debugfs entries for fault-injection capabilities"
950 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
952 Enable configuration of fault-injection capabilities via debugfs.
954 config FAULT_INJECTION_STACKTRACE_FILTER
955 bool "stacktrace filter for fault-injection capabilities"
956 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
959 select FRAME_POINTER if !PPC && !S390
961 Provide stacktrace filter for fault-injection capabilities
964 bool "Latency measuring infrastructure"
965 select FRAME_POINTER if !MIPS && !PPC && !S390
971 depends on HAVE_LATENCYTOP_SUPPORT
973 Enable this option if you want to use the LatencyTOP tool
974 to find out which userspace is blocking on what kernel operations.
976 config SYSCTL_SYSCALL_CHECK
980 sys_sysctl uses binary paths that have been found challenging
981 to properly maintain and use. This enables checks that help
982 you to keep things correct.
984 source mm/Kconfig.debug
985 source kernel/trace/Kconfig
987 config PROVIDE_OHCI1394_DMA_INIT
988 bool "Remote debugging over FireWire early on boot"
989 depends on PCI && X86
991 If you want to debug problems which hang or crash the kernel early
992 on boot and the crashing machine has a FireWire port, you can use
993 this feature to remotely access the memory of the crashed machine
994 over FireWire. This employs remote DMA as part of the OHCI1394
995 specification which is now the standard for FireWire controllers.
997 With remote DMA, you can monitor the printk buffer remotely using
998 firescope and access all memory below 4GB using fireproxy from gdb.
999 Even controlling a kernel debugger is possible using remote DMA.
1003 If ohci1394_dma=early is used as boot parameter, it will initialize
1004 all OHCI1394 controllers which are found in the PCI config space.
1006 As all changes to the FireWire bus such as enabling and disabling
1007 devices cause a bus reset and thereby disable remote DMA for all
1008 devices, be sure to have the cable plugged and FireWire enabled on
1009 the debugging host before booting the debug target for debugging.
1011 This code (~1k) is freed after boot. By then, the firewire stack
1012 in charge of the OHCI-1394 controllers should be used instead.
1014 See Documentation/debugging-via-ohci1394.txt for more information.
1016 config FIREWIRE_OHCI_REMOTE_DMA
1017 bool "Remote debugging over FireWire with firewire-ohci"
1018 depends on FIREWIRE_OHCI
1020 This option lets you use the FireWire bus for remote debugging
1021 with help of the firewire-ohci driver. It enables unfiltered
1022 remote DMA in firewire-ohci.
1023 See Documentation/debugging-via-ohci1394.txt for more information.
1028 bool "Build targets in Documentation/ tree"
1029 depends on HEADERS_CHECK
1031 This option attempts to build objects from the source files in the
1032 kernel Documentation/ tree.
1034 Say N if you are unsure.
1036 config DYNAMIC_DEBUG
1037 bool "Enable dynamic printk() support"
1043 Compiles debug level messages into the kernel, which would not
1044 otherwise be available at runtime. These messages can then be
1045 enabled/disabled based on various levels of scope - per source file,
1046 function, module, format string, and line number. This mechanism
1047 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1048 this compile option is a larger kernel text size of about 2%.
1052 Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
1053 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1054 filesystem must first be mounted before making use of this feature.
1055 We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
1056 file contains a list of the debug statements that can be enabled. The
1057 format for each line of the file is:
1059 filename:lineno [module]function flags format
1061 filename : source file of the debug statement
1062 lineno : line number of the debug statement
1063 module : module that contains the debug statement
1064 function : function that contains the debug statement
1065 flags : 'p' means the line is turned 'on' for printing
1066 format : the format used for the debug statement
1070 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
1071 # filename:lineno [module]function flags format
1072 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1073 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1074 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1078 // enable the message at line 1603 of file svcsock.c
1079 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1080 <debugfs>/dynamic_debug/ddebug
1082 // enable all the messages in file svcsock.c
1083 nullarbor:~ # echo -n 'file svcsock.c +p' >
1084 <debugfs>/dynamic_debug/ddebug
1086 // enable all the messages in the NFS server module
1087 nullarbor:~ # echo -n 'module nfsd +p' >
1088 <debugfs>/dynamic_debug/ddebug
1090 // enable all 12 messages in the function svc_process()
1091 nullarbor:~ # echo -n 'func svc_process +p' >
1092 <debugfs>/dynamic_debug/ddebug
1094 // disable all 12 messages in the function svc_process()
1095 nullarbor:~ # echo -n 'func svc_process -p' >
1096 <debugfs>/dynamic_debug/ddebug
1098 See Documentation/dynamic-debug-howto.txt for additional information.
1100 config DMA_API_DEBUG
1101 bool "Enable debugging of DMA-API usage"
1102 depends on HAVE_DMA_API_DEBUG
1104 Enable this option to debug the use of the DMA API by device drivers.
1105 With this option you will be able to detect common bugs in device
1106 drivers like double-freeing of DMA mappings or freeing mappings that
1107 were never allocated.
1108 This option causes a performance degredation. Use only if you want
1109 to debug device drivers. If unsure, say N.
1111 source "samples/Kconfig"
1113 source "lib/Kconfig.kgdb"
1115 source "lib/Kconfig.kmemcheck"