2 config PRINTK_TIME
3 bool "Show timing information on printks"
4 depends on PRINTK
5 help
6 Selecting this option causes time stamps of the printk()
7 messages to be added to the output of the syslog() system
8 call and at the console.
10 The timestamp is always recorded internally, and exported
11 to /dev/kmsg. This flag just specifies if the timestamp should
12 be included, not that the timestamp is recorded.
14 The behavior is also controlled by the kernel command line
15 parameter printk.time=1. See Documentation/kernel-parameters.txt
17 config DEFAULT_MESSAGE_LOGLEVEL
18 int "Default message log level (1-7)"
19 range 1 7
20 default "4"
21 help
22 Default log level for printk statements with no specified priority.
24 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
25 that are auditing their logs closely may want to set it to a lower
26 priority.
28 config ENABLE_WARN_DEPRECATED
29 bool "Enable __deprecated logic"
30 default y
31 help
32 Enable the __deprecated logic in the kernel build.
33 Disable this to suppress the "warning: 'foo' is deprecated
34 (declared at kernel/power/somefile.c:1234)" messages.
36 config ENABLE_MUST_CHECK
37 bool "Enable __must_check logic"
38 default y
39 help
40 Enable the __must_check logic in the kernel build. Disable this to
41 suppress the "warning: ignoring return value of 'foo', declared with
42 attribute warn_unused_result" messages.
44 config FRAME_WARN
45 int "Warn for stack frames larger than (needs gcc 4.4)"
46 range 0 8192
47 default 1024 if !64BIT
48 default 2048 if 64BIT
49 help
50 Tell gcc to warn at build time for stack frames larger than this.
51 Setting this too low will cause a lot of warnings.
52 Setting it to 0 disables the warning.
53 Requires gcc 4.4
55 config MAGIC_SYSRQ
56 bool "Magic SysRq key"
57 depends on !UML
58 help
59 If you say Y here, you will have some control over the system even
60 if the system crashes for example during kernel debugging (e.g., you
61 will be able to flush the buffer cache to disk, reboot the system
62 immediately or dump some status information). This is accomplished
63 by pressing various keys while holding SysRq (Alt+PrintScreen). It
64 also works on a serial console (on PC hardware at least), if you
65 send a BREAK and then within 5 seconds a command keypress. The
66 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
67 unless you really know what this hack does.
69 config STRIP_ASM_SYMS
70 bool "Strip assembler-generated symbols during link"
71 default n
72 help
73 Strip internal assembler-generated symbols during a link (symbols
74 that look like '.Lxxx') so they don't pollute the output of
75 get_wchan() and suchlike.
77 config READABLE_ASM
78 bool "Generate readable assembler code"
79 depends on DEBUG_KERNEL
80 help
81 Disable some compiler optimizations that tend to generate human unreadable
82 assembler output. This may make the kernel slightly slower, but it helps
83 to keep kernel developers who have to stare a lot at assembler listings
84 sane.
86 config UNUSED_SYMBOLS
87 bool "Enable unused/obsolete exported symbols"
88 default y if X86
89 help
90 Unused but exported symbols make the kernel needlessly bigger. For
91 that reason most of these unused exports will soon be removed. This
92 option is provided temporarily to provide a transition period in case
93 some external kernel module needs one of these symbols anyway. If you
94 encounter such a case in your module, consider if you are actually
95 using the right API. (rationale: since nobody in the kernel is using
96 this in a module, there is a pretty good chance it's actually the
97 wrong interface to use). If you really need the symbol, please send a
98 mail to the linux kernel mailing list mentioning the symbol and why
99 you really need it, and what the merge plan to the mainline kernel for
100 your module is.
102 config DEBUG_FS
103 bool "Debug Filesystem"
104 help
105 debugfs is a virtual file system that kernel developers use to put
106 debugging files into. Enable this option to be able to read and
107 write to these files.
109 For detailed documentation on the debugfs API, see
110 Documentation/DocBook/filesystems.
112 If unsure, say N.
114 config HEADERS_CHECK
115 bool "Run 'make headers_check' when building vmlinux"
116 depends on !UML
117 help
118 This option will extract the user-visible kernel headers whenever
119 building the kernel, and will run basic sanity checks on them to
120 ensure that exported files do not attempt to include files which
121 were not exported, etc.
123 If you're making modifications to header files which are
124 relevant for userspace, say 'Y', and check the headers
125 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
126 your build tree), to make sure they're suitable.
128 config DEBUG_SECTION_MISMATCH
129 bool "Enable full Section mismatch analysis"
130 help
131 The section mismatch analysis checks if there are illegal
132 references from one section to another section.
133 During linktime or runtime, some sections are dropped;
134 any use of code/data previously in these sections would
135 most likely result in an oops.
136 In the code, functions and variables are annotated with
137 __init, __cpuinit, etc. (see the full list in include/linux/init.h),
138 which results in the code/data being placed in specific sections.
139 The section mismatch analysis is always performed after a full
140 kernel build, and enabling this option causes the following
141 additional steps to occur:
142 - Add the option -fno-inline-functions-called-once to gcc commands.
143 When inlining a function annotated with __init in a non-init
144 function, we would lose the section information and thus
145 the analysis would not catch the illegal reference.
146 This option tells gcc to inline less (but it does result in
147 a larger kernel).
148 - Run the section mismatch analysis for each module/built-in.o file.
149 When we run the section mismatch analysis on vmlinux.o, we
150 lose valueble information about where the mismatch was
151 introduced.
152 Running the analysis for each module/built-in.o file
153 tells where the mismatch happens much closer to the
154 source. The drawback is that the same mismatch is
155 reported at least twice.
156 - Enable verbose reporting from modpost in order to help resolve
157 the section mismatches that are reported.
159 config DEBUG_KERNEL
160 bool "Kernel debugging"
161 help
162 Say Y here if you are developing drivers or trying to debug and
163 identify kernel problems.
165 config DEBUG_SHIRQ
166 bool "Debug shared IRQ handlers"
167 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
168 help
169 Enable this to generate a spurious interrupt as soon as a shared
170 interrupt handler is registered, and just before one is deregistered.
171 Drivers ought to be able to handle interrupts coming in at those
172 points; some don't and need to be caught.
174 config LOCKUP_DETECTOR
175 bool "Detect Hard and Soft Lockups"
176 depends on DEBUG_KERNEL && !S390
177 help
178 Say Y here to enable the kernel to act as a watchdog to detect
179 hard and soft lockups.
181 Softlockups are bugs that cause the kernel to loop in kernel
182 mode for more than 20 seconds, without giving other tasks a
183 chance to run. The current stack trace is displayed upon
184 detection and the system will stay locked up.
186 Hardlockups are bugs that cause the CPU to loop in kernel mode
187 for more than 10 seconds, without letting other interrupts have a
188 chance to run. The current stack trace is displayed upon detection
189 and the system will stay locked up.
191 The overhead should be minimal. A periodic hrtimer runs to
192 generate interrupts and kick the watchdog task every 4 seconds.
193 An NMI is generated every 10 seconds or so to check for hardlockups.
194 If NMIs are not available on the platform, every 12 seconds the
195 hrtimer interrupt on one cpu will be used to check for hardlockups
196 on the next cpu.
198 The frequency of hrtimer and NMI events and the soft and hard lockup
199 thresholds can be controlled through the sysctl watchdog_thresh.
201 config HARDLOCKUP_DETECTOR_NMI
202 def_bool y
203 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
204 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
206 config HARDLOCKUP_DETECTOR_OTHER_CPU
207 def_bool y
208 depends on LOCKUP_DETECTOR && SMP
209 depends on !HARDLOCKUP_DETECTOR_NMI && !HAVE_NMI_WATCHDOG
211 config HARDLOCKUP_DETECTOR
212 def_bool y
213 depends on HARDLOCKUP_DETECTOR_NMI || HARDLOCKUP_DETECTOR_OTHER_CPU
215 config BOOTPARAM_HARDLOCKUP_PANIC
216 bool "Panic (Reboot) On Hard Lockups"
217 depends on HARDLOCKUP_DETECTOR
218 help
219 Say Y here to enable the kernel to panic on "hard lockups",
220 which are bugs that cause the kernel to loop in kernel
221 mode with interrupts disabled for more than 10 seconds (configurable
222 using the watchdog_thresh sysctl).
224 Say N if unsure.
226 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
227 int
228 depends on HARDLOCKUP_DETECTOR
229 range 0 1
230 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
231 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
233 config BOOTPARAM_SOFTLOCKUP_PANIC
234 bool "Panic (Reboot) On Soft Lockups"
235 depends on LOCKUP_DETECTOR
236 help
237 Say Y here to enable the kernel to panic on "soft lockups",
238 which are bugs that cause the kernel to loop in kernel
239 mode for more than 20 seconds (configurable using the watchdog_thresh
240 sysctl), without giving other tasks a chance to run.
242 The panic can be used in combination with panic_timeout,
243 to cause the system to reboot automatically after a
244 lockup has been detected. This feature is useful for
245 high-availability systems that have uptime guarantees and
246 where a lockup must be resolved ASAP.
248 Say N if unsure.
250 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
251 int
252 depends on LOCKUP_DETECTOR
253 range 0 1
254 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
255 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
257 config PANIC_ON_OOPS
258 bool "Panic on Oops" if EXPERT
259 default n
260 help
261 Say Y here to enable the kernel to panic when it oopses. This
262 has the same effect as setting oops=panic on the kernel command
263 line.
265 This feature is useful to ensure that the kernel does not do
266 anything erroneous after an oops which could result in data
267 corruption or other issues.
269 Say N if unsure.
271 config PANIC_ON_OOPS_VALUE
272 int
273 range 0 1
274 default 0 if !PANIC_ON_OOPS
275 default 1 if PANIC_ON_OOPS
277 config DETECT_HUNG_TASK
278 bool "Detect Hung Tasks"
279 depends on DEBUG_KERNEL
280 default LOCKUP_DETECTOR
281 help
282 Say Y here to enable the kernel to detect "hung tasks",
283 which are bugs that cause the task to be stuck in
284 uninterruptible "D" state indefinitiley.
286 When a hung task is detected, the kernel will print the
287 current stack trace (which you should report), but the
288 task will stay in uninterruptible state. If lockdep is
289 enabled then all held locks will also be reported. This
290 feature has negligible overhead.
292 config DEFAULT_HUNG_TASK_TIMEOUT
293 int "Default timeout for hung task detection (in seconds)"
294 depends on DETECT_HUNG_TASK
295 default 120
296 help
297 This option controls the default timeout (in seconds) used
298 to determine when a task has become non-responsive and should
299 be considered hung.
301 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
302 sysctl or by writing a value to
303 /proc/sys/kernel/hung_task_timeout_secs.
305 A timeout of 0 disables the check. The default is two minutes.
306 Keeping the default should be fine in most cases.
308 config BOOTPARAM_HUNG_TASK_PANIC
309 bool "Panic (Reboot) On Hung Tasks"
310 depends on DETECT_HUNG_TASK
311 help
312 Say Y here to enable the kernel to panic on "hung tasks",
313 which are bugs that cause the kernel to leave a task stuck
314 in uninterruptible "D" state.
316 The panic can be used in combination with panic_timeout,
317 to cause the system to reboot automatically after a
318 hung task has been detected. This feature is useful for
319 high-availability systems that have uptime guarantees and
320 where a hung tasks must be resolved ASAP.
322 Say N if unsure.
324 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
325 int
326 depends on DETECT_HUNG_TASK
327 range 0 1
328 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
329 default 1 if BOOTPARAM_HUNG_TASK_PANIC
331 config SCHED_DEBUG
332 bool "Collect scheduler debugging info"
333 depends on DEBUG_KERNEL && PROC_FS
334 default y
335 help
336 If you say Y here, the /proc/sched_debug file will be provided
337 that can help debug the scheduler. The runtime overhead of this
338 option is minimal.
340 config SCHEDSTATS
341 bool "Collect scheduler statistics"
342 depends on DEBUG_KERNEL && PROC_FS
343 help
344 If you say Y here, additional code will be inserted into the
345 scheduler and related routines to collect statistics about
346 scheduler behavior and provide them in /proc/schedstat. These
347 stats may be useful for both tuning and debugging the scheduler
348 If you aren't debugging the scheduler or trying to tune a specific
349 application, you can say N to avoid the very slight overhead
350 this adds.
352 config TIMER_STATS
353 bool "Collect kernel timers statistics"
354 depends on DEBUG_KERNEL && PROC_FS
355 help
356 If you say Y here, additional code will be inserted into the
357 timer routines to collect statistics about kernel timers being
358 reprogrammed. The statistics can be read from /proc/timer_stats.
359 The statistics collection is started by writing 1 to /proc/timer_stats,
360 writing 0 stops it. This feature is useful to collect information
361 about timer usage patterns in kernel and userspace. This feature
362 is lightweight if enabled in the kernel config but not activated
363 (it defaults to deactivated on bootup and will only be activated
364 if some application like powertop activates it explicitly).
366 config DEBUG_OBJECTS
367 bool "Debug object operations"
368 depends on DEBUG_KERNEL
369 help
370 If you say Y here, additional code will be inserted into the
371 kernel to track the life time of various objects and validate
372 the operations on those objects.
374 config DEBUG_OBJECTS_SELFTEST
375 bool "Debug objects selftest"
376 depends on DEBUG_OBJECTS
377 help
378 This enables the selftest of the object debug code.
380 config DEBUG_OBJECTS_FREE
381 bool "Debug objects in freed memory"
382 depends on DEBUG_OBJECTS
383 help
384 This enables checks whether a k/v free operation frees an area
385 which contains an object which has not been deactivated
386 properly. This can make kmalloc/kfree-intensive workloads
387 much slower.
389 config DEBUG_OBJECTS_TIMERS
390 bool "Debug timer objects"
391 depends on DEBUG_OBJECTS
392 help
393 If you say Y here, additional code will be inserted into the
394 timer routines to track the life time of timer objects and
395 validate the timer operations.
397 config DEBUG_OBJECTS_WORK
398 bool "Debug work objects"
399 depends on DEBUG_OBJECTS
400 help
401 If you say Y here, additional code will be inserted into the
402 work queue routines to track the life time of work objects and
403 validate the work operations.
405 config DEBUG_OBJECTS_RCU_HEAD
406 bool "Debug RCU callbacks objects"
407 depends on DEBUG_OBJECTS
408 help
409 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
411 config DEBUG_OBJECTS_PERCPU_COUNTER
412 bool "Debug percpu counter objects"
413 depends on DEBUG_OBJECTS
414 help
415 If you say Y here, additional code will be inserted into the
416 percpu counter routines to track the life time of percpu counter
417 objects and validate the percpu counter operations.
419 config DEBUG_OBJECTS_ENABLE_DEFAULT
420 int "debug_objects bootup default value (0-1)"
421 range 0 1
422 default "1"
423 depends on DEBUG_OBJECTS
424 help
425 Debug objects boot parameter default value
427 config DEBUG_SLAB
428 bool "Debug slab memory allocations"
429 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
430 help
431 Say Y here to have the kernel do limited verification on memory
432 allocation as well as poisoning memory on free to catch use of freed
433 memory. This can make kmalloc/kfree-intensive workloads much slower.
435 config DEBUG_SLAB_LEAK
436 bool "Memory leak debugging"
437 depends on DEBUG_SLAB
439 config SLUB_DEBUG_ON
440 bool "SLUB debugging on by default"
441 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
442 default n
443 help
444 Boot with debugging on by default. SLUB boots by default with
445 the runtime debug capabilities switched off. Enabling this is
446 equivalent to specifying the "slub_debug" parameter on boot.
447 There is no support for more fine grained debug control like
448 possible with slub_debug=xxx. SLUB debugging may be switched
449 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
450 "slub_debug=-".
452 config SLUB_STATS
453 default n
454 bool "Enable SLUB performance statistics"
455 depends on SLUB && SYSFS
456 help
457 SLUB statistics are useful to debug SLUBs allocation behavior in
458 order find ways to optimize the allocator. This should never be
459 enabled for production use since keeping statistics slows down
460 the allocator by a few percentage points. The slabinfo command
461 supports the determination of the most active slabs to figure
462 out which slabs are relevant to a particular load.
463 Try running: slabinfo -DA
465 config HAVE_DEBUG_KMEMLEAK
466 bool
468 config DEBUG_KMEMLEAK
469 bool "Kernel memory leak detector"
470 depends on DEBUG_KERNEL && EXPERIMENTAL && HAVE_DEBUG_KMEMLEAK
471 select DEBUG_FS
472 select STACKTRACE if STACKTRACE_SUPPORT
473 select KALLSYMS
474 select CRC32
475 help
476 Say Y here if you want to enable the memory leak
477 detector. The memory allocation/freeing is traced in a way
478 similar to the Boehm's conservative garbage collector, the
479 difference being that the orphan objects are not freed but
480 only shown in /sys/kernel/debug/kmemleak. Enabling this
481 feature will introduce an overhead to memory
482 allocations. See Documentation/kmemleak.txt for more
483 details.
485 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
486 of finding leaks due to the slab objects poisoning.
488 In order to access the kmemleak file, debugfs needs to be
489 mounted (usually at /sys/kernel/debug).
491 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
492 int "Maximum kmemleak early log entries"
493 depends on DEBUG_KMEMLEAK
494 range 200 40000
495 default 400
496 help
497 Kmemleak must track all the memory allocations to avoid
498 reporting false positives. Since memory may be allocated or
499 freed before kmemleak is initialised, an early log buffer is
500 used to store these actions. If kmemleak reports "early log
501 buffer exceeded", please increase this value.
503 config DEBUG_KMEMLEAK_TEST
504 tristate "Simple test for the kernel memory leak detector"
505 depends on DEBUG_KMEMLEAK && m
506 help
507 This option enables a module that explicitly leaks memory.
509 If unsure, say N.
511 config DEBUG_KMEMLEAK_DEFAULT_OFF
512 bool "Default kmemleak to off"
513 depends on DEBUG_KMEMLEAK
514 help
515 Say Y here to disable kmemleak by default. It can then be enabled
516 on the command line via kmemleak=on.
518 config DEBUG_PREEMPT
519 bool "Debug preemptible kernel"
520 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
521 default y
522 help
523 If you say Y here then the kernel will use a debug variant of the
524 commonly used smp_processor_id() function and will print warnings
525 if kernel code uses it in a preemption-unsafe way. Also, the kernel
526 will detect preemption count underflows.
528 config DEBUG_RT_MUTEXES
529 bool "RT Mutex debugging, deadlock detection"
530 depends on DEBUG_KERNEL && RT_MUTEXES
531 help
532 This allows rt mutex semantics violations and rt mutex related
533 deadlocks (lockups) to be detected and reported automatically.
535 config DEBUG_PI_LIST
536 bool
537 default y
538 depends on DEBUG_RT_MUTEXES
540 config RT_MUTEX_TESTER
541 bool "Built-in scriptable tester for rt-mutexes"
542 depends on DEBUG_KERNEL && RT_MUTEXES
543 help
544 This option enables a rt-mutex tester.
546 config DEBUG_SPINLOCK
547 bool "Spinlock and rw-lock debugging: basic checks"
548 depends on DEBUG_KERNEL
549 select UNINLINE_SPIN_UNLOCK
550 help
551 Say Y here and build SMP to catch missing spinlock initialization
552 and certain other kinds of spinlock errors commonly made. This is
553 best used in conjunction with the NMI watchdog so that spinlock
554 deadlocks are also debuggable.
556 config DEBUG_MUTEXES
557 bool "Mutex debugging: basic checks"
558 depends on DEBUG_KERNEL
559 help
560 This feature allows mutex semantics violations to be detected and
561 reported.
563 config DEBUG_LOCK_ALLOC
564 bool "Lock debugging: detect incorrect freeing of live locks"
565 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
566 select DEBUG_SPINLOCK
567 select DEBUG_MUTEXES
568 select LOCKDEP
569 help
570 This feature will check whether any held lock (spinlock, rwlock,
571 mutex or rwsem) is incorrectly freed by the kernel, via any of the
572 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
573 vfree(), etc.), whether a live lock is incorrectly reinitialized via
574 spin_lock_init()/mutex_init()/etc., or whether there is any lock
575 held during task exit.
577 config PROVE_LOCKING
578 bool "Lock debugging: prove locking correctness"
579 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
580 select LOCKDEP
581 select DEBUG_SPINLOCK
582 select DEBUG_MUTEXES
583 select DEBUG_LOCK_ALLOC
584 select TRACE_IRQFLAGS
585 default n
586 help
587 This feature enables the kernel to prove that all locking
588 that occurs in the kernel runtime is mathematically
589 correct: that under no circumstance could an arbitrary (and
590 not yet triggered) combination of observed locking
591 sequences (on an arbitrary number of CPUs, running an
592 arbitrary number of tasks and interrupt contexts) cause a
593 deadlock.
595 In short, this feature enables the kernel to report locking
596 related deadlocks before they actually occur.
598 The proof does not depend on how hard and complex a
599 deadlock scenario would be to trigger: how many
600 participant CPUs, tasks and irq-contexts would be needed
601 for it to trigger. The proof also does not depend on
602 timing: if a race and a resulting deadlock is possible
603 theoretically (no matter how unlikely the race scenario
604 is), it will be proven so and will immediately be
605 reported by the kernel (once the event is observed that
606 makes the deadlock theoretically possible).
608 If a deadlock is impossible (i.e. the locking rules, as
609 observed by the kernel, are mathematically correct), the
610 kernel reports nothing.
612 NOTE: this feature can also be enabled for rwlocks, mutexes
613 and rwsems - in which case all dependencies between these
614 different locking variants are observed and mapped too, and
615 the proof of observed correctness is also maintained for an
616 arbitrary combination of these separate locking variants.
618 For more details, see Documentation/lockdep-design.txt.
620 config PROVE_RCU
621 bool "RCU debugging: prove RCU correctness"
622 depends on PROVE_LOCKING
623 default n
624 help
625 This feature enables lockdep extensions that check for correct
626 use of RCU APIs. This is currently under development. Say Y
627 if you want to debug RCU usage or help work on the PROVE_RCU
628 feature.
630 Say N if you are unsure.
632 config PROVE_RCU_REPEATEDLY
633 bool "RCU debugging: don't disable PROVE_RCU on first splat"
634 depends on PROVE_RCU
635 default n
636 help
637 By itself, PROVE_RCU will disable checking upon issuing the
638 first warning (or "splat"). This feature prevents such
639 disabling, allowing multiple RCU-lockdep warnings to be printed
640 on a single reboot.
642 Say Y to allow multiple RCU-lockdep warnings per boot.
644 Say N if you are unsure.
646 config PROVE_RCU_DELAY
647 bool "RCU debugging: preemptible RCU race provocation"
648 depends on DEBUG_KERNEL && PREEMPT_RCU
649 default n
650 help
651 There is a class of races that involve an unlikely preemption
652 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
653 been set to INT_MIN. This feature inserts a delay at that
654 point to increase the probability of these races.
656 Say Y to increase probability of preemption of __rcu_read_unlock().
658 Say N if you are unsure.
660 config SPARSE_RCU_POINTER
661 bool "RCU debugging: sparse-based checks for pointer usage"
662 default n
663 help
664 This feature enables the __rcu sparse annotation for
665 RCU-protected pointers. This annotation will cause sparse
666 to flag any non-RCU used of annotated pointers. This can be
667 helpful when debugging RCU usage. Please note that this feature
668 is not intended to enforce code cleanliness; it is instead merely
669 a debugging aid.
671 Say Y to make sparse flag questionable use of RCU-protected pointers
673 Say N if you are unsure.
675 config LOCKDEP
676 bool
677 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
678 select STACKTRACE
679 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
680 select KALLSYMS
681 select KALLSYMS_ALL
683 config LOCK_STAT
684 bool "Lock usage statistics"
685 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
686 select LOCKDEP
687 select DEBUG_SPINLOCK
688 select DEBUG_MUTEXES
689 select DEBUG_LOCK_ALLOC
690 default n
691 help
692 This feature enables tracking lock contention points
694 For more details, see Documentation/lockstat.txt
696 This also enables lock events required by "perf lock",
697 subcommand of perf.
698 If you want to use "perf lock", you also need to turn on
699 CONFIG_EVENT_TRACING.
701 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
702 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
704 config DEBUG_LOCKDEP
705 bool "Lock dependency engine debugging"
706 depends on DEBUG_KERNEL && LOCKDEP
707 help
708 If you say Y here, the lock dependency engine will do
709 additional runtime checks to debug itself, at the price
710 of more runtime overhead.
712 config TRACE_IRQFLAGS
713 bool
714 help
715 Enables hooks to interrupt enabling and disabling for
716 either tracing or lock debugging.
718 config DEBUG_ATOMIC_SLEEP
719 bool "Sleep inside atomic section checking"
720 select PREEMPT_COUNT
721 depends on DEBUG_KERNEL
722 help
723 If you say Y here, various routines which may sleep will become very
724 noisy if they are called inside atomic sections: when a spinlock is
725 held, inside an rcu read side critical section, inside preempt disabled
726 sections, inside an interrupt, etc...
728 config DEBUG_LOCKING_API_SELFTESTS
729 bool "Locking API boot-time self-tests"
730 depends on DEBUG_KERNEL
731 help
732 Say Y here if you want the kernel to run a short self-test during
733 bootup. The self-test checks whether common types of locking bugs
734 are detected by debugging mechanisms or not. (if you disable
735 lock debugging then those bugs wont be detected of course.)
736 The following locking APIs are covered: spinlocks, rwlocks,
737 mutexes and rwsems.
739 config STACKTRACE
740 bool "Stacktrace"
741 depends on STACKTRACE_SUPPORT
742 default y
744 config DEBUG_STACK_USAGE
745 bool "Stack utilization instrumentation"
746 depends on DEBUG_KERNEL && !IA64 && !PARISC
747 help
748 Enables the display of the minimum amount of free stack which each
749 task has ever had available in the sysrq-T and sysrq-P debug output.
751 This option will slow down process creation somewhat.
753 config DEBUG_KOBJECT
754 bool "kobject debugging"
755 depends on DEBUG_KERNEL
756 help
757 If you say Y here, some extra kobject debugging messages will be sent
758 to the syslog.
760 config DEBUG_HIGHMEM
761 bool "Highmem debugging"
762 depends on DEBUG_KERNEL && HIGHMEM
763 help
764 This options enables addition error checking for high memory systems.
765 Disable for production systems.
767 config HAVE_DEBUG_BUGVERBOSE
768 bool
770 config DEBUG_BUGVERBOSE
771 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
772 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
773 default y
774 help
775 Say Y here to make BUG() panics output the file name and line number
776 of the BUG call as well as the EIP and oops trace. This aids
777 debugging but costs about 70-100K of memory.
779 config DEBUG_INFO
780 bool "Compile the kernel with debug info"
781 depends on DEBUG_KERNEL
782 help
783 If you say Y here the resulting kernel image will include
784 debugging info resulting in a larger kernel image.
785 This adds debug symbols to the kernel and modules (gcc -g), and
786 is needed if you intend to use kernel crashdump or binary object
787 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
788 Say Y here only if you plan to debug the kernel.
790 If unsure, say N.
792 config DEBUG_INFO_REDUCED
793 bool "Reduce debugging information"
794 depends on DEBUG_INFO
795 help
796 If you say Y here gcc is instructed to generate less debugging
797 information for structure types. This means that tools that
798 need full debugging information (like kgdb or systemtap) won't
799 be happy. But if you merely need debugging information to
800 resolve line numbers there is no loss. Advantage is that
801 build directory object sizes shrink dramatically over a full
802 DEBUG_INFO build and compile times are reduced too.
803 Only works with newer gcc versions.
805 config DEBUG_VM
806 bool "Debug VM"
807 depends on DEBUG_KERNEL
808 help
809 Enable this to turn on extended checks in the virtual-memory system
810 that may impact performance.
812 If unsure, say N.
814 config DEBUG_VM_RB
815 bool "Debug VM red-black trees"
816 depends on DEBUG_VM
817 help
818 Enable this to turn on more extended checks in the virtual-memory
819 system that may impact performance.
821 If unsure, say N.
823 config DEBUG_VIRTUAL
824 bool "Debug VM translations"
825 depends on DEBUG_KERNEL && X86
826 help
827 Enable some costly sanity checks in virtual to page code. This can
828 catch mistakes with virt_to_page() and friends.
830 If unsure, say N.
832 config DEBUG_NOMMU_REGIONS
833 bool "Debug the global anon/private NOMMU mapping region tree"
834 depends on DEBUG_KERNEL && !MMU
835 help
836 This option causes the global tree of anonymous and private mapping
837 regions to be regularly checked for invalid topology.
839 config DEBUG_WRITECOUNT
840 bool "Debug filesystem writers count"
841 depends on DEBUG_KERNEL
842 help
843 Enable this to catch wrong use of the writers count in struct
844 vfsmount. This will increase the size of each file struct by
845 32 bits.
847 If unsure, say N.
849 config DEBUG_MEMORY_INIT
850 bool "Debug memory initialisation" if EXPERT
851 default !EXPERT
852 help
853 Enable this for additional checks during memory initialisation.
854 The sanity checks verify aspects of the VM such as the memory model
855 and other information provided by the architecture. Verbose
856 information will be printed at KERN_DEBUG loglevel depending
857 on the mminit_loglevel= command-line option.
859 If unsure, say Y
861 config DEBUG_LIST
862 bool "Debug linked list manipulation"
863 depends on DEBUG_KERNEL
864 help
865 Enable this to turn on extended checks in the linked-list
866 walking routines.
868 If unsure, say N.
870 config TEST_LIST_SORT
871 bool "Linked list sorting test"
872 depends on DEBUG_KERNEL
873 help
874 Enable this to turn on 'list_sort()' function test. This test is
875 executed only once during system boot, so affects only boot time.
877 If unsure, say N.
879 config DEBUG_SG
880 bool "Debug SG table operations"
881 depends on DEBUG_KERNEL
882 help
883 Enable this to turn on checks on scatter-gather tables. This can
884 help find problems with drivers that do not properly initialize
885 their sg tables.
887 If unsure, say N.
889 config DEBUG_NOTIFIERS
890 bool "Debug notifier call chains"
891 depends on DEBUG_KERNEL
892 help
893 Enable this to turn on sanity checking for notifier call chains.
894 This is most useful for kernel developers to make sure that
895 modules properly unregister themselves from notifier chains.
896 This is a relatively cheap check but if you care about maximum
897 performance, say N.
899 config DEBUG_CREDENTIALS
900 bool "Debug credential management"
901 depends on DEBUG_KERNEL
902 help
903 Enable this to turn on some debug checking for credential
904 management. The additional code keeps track of the number of
905 pointers from task_structs to any given cred struct, and checks to
906 see that this number never exceeds the usage count of the cred
907 struct.
909 Furthermore, if SELinux is enabled, this also checks that the
910 security pointer in the cred struct is never seen to be invalid.
912 If unsure, say N.
914 #
915 # Select this config option from the architecture Kconfig, if it
916 # is preferred to always offer frame pointers as a config
917 # option on the architecture (regardless of KERNEL_DEBUG):
918 #
919 config ARCH_WANT_FRAME_POINTERS
920 bool
921 help
923 config FRAME_POINTER
924 bool "Compile the kernel with frame pointers"
925 depends on DEBUG_KERNEL && \
926 (CRIS || M68K || FRV || UML || \
927 AVR32 || SUPERH || BLACKFIN || MN10300) || \
928 ARCH_WANT_FRAME_POINTERS
929 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
930 help
931 If you say Y here the resulting kernel image will be slightly
932 larger and slower, but it gives very useful debugging information
933 in case of kernel bugs. (precise oopses/stacktraces/warnings)
935 config BOOT_PRINTK_DELAY
936 bool "Delay each boot printk message by N milliseconds"
937 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
938 help
939 This build option allows you to read kernel boot messages
940 by inserting a short delay after each one. The delay is
941 specified in milliseconds on the kernel command line,
942 using "boot_delay=N".
944 It is likely that you would also need to use "lpj=M" to preset
945 the "loops per jiffie" value.
946 See a previous boot log for the "lpj" value to use for your
947 system, and then set "lpj=M" before setting "boot_delay=N".
948 NOTE: Using this option may adversely affect SMP systems.
949 I.e., processors other than the first one may not boot up.
950 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
951 what it believes to be lockup conditions.
953 config RCU_TORTURE_TEST
954 tristate "torture tests for RCU"
955 depends on DEBUG_KERNEL
956 default n
957 help
958 This option provides a kernel module that runs torture tests
959 on the RCU infrastructure. The kernel module may be built
960 after the fact on the running kernel to be tested, if desired.
962 Say Y here if you want RCU torture tests to be built into
963 the kernel.
964 Say M if you want the RCU torture tests to build as a module.
965 Say N if you are unsure.
967 config RCU_TORTURE_TEST_RUNNABLE
968 bool "torture tests for RCU runnable by default"
969 depends on RCU_TORTURE_TEST = y
970 default n
971 help
972 This option provides a way to build the RCU torture tests
973 directly into the kernel without them starting up at boot
974 time. You can use /proc/sys/kernel/rcutorture_runnable
975 to manually override this setting. This /proc file is
976 available only when the RCU torture tests have been built
977 into the kernel.
979 Say Y here if you want the RCU torture tests to start during
980 boot (you probably don't).
981 Say N here if you want the RCU torture tests to start only
982 after being manually enabled via /proc.
984 config RCU_CPU_STALL_TIMEOUT
985 int "RCU CPU stall timeout in seconds"
986 depends on TREE_RCU || TREE_PREEMPT_RCU
987 range 3 300
988 default 21
989 help
990 If a given RCU grace period extends more than the specified
991 number of seconds, a CPU stall warning is printed. If the
992 RCU grace period persists, additional CPU stall warnings are
993 printed at more widely spaced intervals.
995 config RCU_CPU_STALL_VERBOSE
996 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
997 depends on TREE_PREEMPT_RCU
998 default y
999 help
1000 This option causes RCU to printk detailed per-task information
1001 for any tasks that are stalling the current RCU grace period.
1003 Say N if you are unsure.
1005 Say Y if you want to enable such checks.
1007 config RCU_CPU_STALL_INFO
1008 bool "Print additional diagnostics on RCU CPU stall"
1009 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1010 default n
1011 help
1012 For each stalled CPU that is aware of the current RCU grace
1013 period, print out additional per-CPU diagnostic information
1014 regarding scheduling-clock ticks, idle state, and,
1015 for RCU_FAST_NO_HZ kernels, idle-entry state.
1017 Say N if you are unsure.
1019 Say Y if you want to enable such diagnostics.
1021 config RCU_TRACE
1022 bool "Enable tracing for RCU"
1023 depends on DEBUG_KERNEL
1024 help
1025 This option provides tracing in RCU which presents stats
1026 in debugfs for debugging RCU implementation.
1028 Say Y here if you want to enable RCU tracing
1029 Say N if you are unsure.
1031 config KPROBES_SANITY_TEST
1032 bool "Kprobes sanity tests"
1033 depends on DEBUG_KERNEL
1034 depends on KPROBES
1035 default n
1036 help
1037 This option provides for testing basic kprobes functionality on
1038 boot. A sample kprobe, jprobe and kretprobe are inserted and
1039 verified for functionality.
1041 Say N if you are unsure.
1043 config BACKTRACE_SELF_TEST
1044 tristate "Self test for the backtrace code"
1045 depends on DEBUG_KERNEL
1046 default n
1047 help
1048 This option provides a kernel module that can be used to test
1049 the kernel stack backtrace code. This option is not useful
1050 for distributions or general kernels, but only for kernel
1051 developers working on architecture code.
1053 Note that if you want to also test saved backtraces, you will
1054 have to enable STACKTRACE as well.
1056 Say N if you are unsure.
1058 config DEBUG_BLOCK_EXT_DEVT
1059 bool "Force extended block device numbers and spread them"
1060 depends on DEBUG_KERNEL
1061 depends on BLOCK
1062 default n
1063 help
1064 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1065 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1066 YOU ARE DOING. Distros, please enable this and fix whatever
1067 is broken.
1069 Conventionally, block device numbers are allocated from
1070 predetermined contiguous area. However, extended block area
1071 may introduce non-contiguous block device numbers. This
1072 option forces most block device numbers to be allocated from
1073 the extended space and spreads them to discover kernel or
1074 userland code paths which assume predetermined contiguous
1075 device number allocation.
1077 Note that turning on this debug option shuffles all the
1078 device numbers for all IDE and SCSI devices including libata
1079 ones, so root partition specified using device number
1080 directly (via rdev or root=MAJ:MIN) won't work anymore.
1081 Textual device names (root=/dev/sdXn) will continue to work.
1083 Say N if you are unsure.
1085 config DEBUG_FORCE_WEAK_PER_CPU
1086 bool "Force weak per-cpu definitions"
1087 depends on DEBUG_KERNEL
1088 help
1089 s390 and alpha require percpu variables in modules to be
1090 defined weak to work around addressing range issue which
1091 puts the following two restrictions on percpu variable
1092 definitions.
1094 1. percpu symbols must be unique whether static or not
1095 2. percpu variables can't be defined inside a function
1097 To ensure that generic code follows the above rules, this
1098 option forces all percpu variables to be defined as weak.
1100 config DEBUG_PER_CPU_MAPS
1101 bool "Debug access to per_cpu maps"
1102 depends on DEBUG_KERNEL
1103 depends on SMP
1104 help
1105 Say Y to verify that the per_cpu map being accessed has
1106 been set up. This adds a fair amount of code to kernel memory
1107 and decreases performance.
1109 Say N if unsure.
1111 config LKDTM
1112 tristate "Linux Kernel Dump Test Tool Module"
1113 depends on DEBUG_FS
1114 depends on BLOCK
1115 default n
1116 help
1117 This module enables testing of the different dumping mechanisms by
1118 inducing system failures at predefined crash points.
1119 If you don't need it: say N
1120 Choose M here to compile this code as a module. The module will be
1121 called lkdtm.
1123 Documentation on how to use the module can be found in
1124 Documentation/fault-injection/provoke-crashes.txt
1126 config NOTIFIER_ERROR_INJECTION
1127 tristate "Notifier error injection"
1128 depends on DEBUG_KERNEL
1129 select DEBUG_FS
1130 help
1131 This option provides the ability to inject artificial errors to
1132 specified notifier chain callbacks. It is useful to test the error
1133 handling of notifier call chain failures.
1135 Say N if unsure.
1137 config CPU_NOTIFIER_ERROR_INJECT
1138 tristate "CPU notifier error injection module"
1139 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1140 help
1141 This option provides a kernel module that can be used to test
1142 the error handling of the cpu notifiers by injecting artificial
1143 errors to CPU notifier chain callbacks. It is controlled through
1144 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1146 If the notifier call chain should be failed with some events
1147 notified, write the error code to "actions/<notifier event>/error".
1149 Example: Inject CPU offline error (-1 == -EPERM)
1151 # cd /sys/kernel/debug/notifier-error-inject/cpu
1152 # echo -1 > actions/CPU_DOWN_PREPARE/error
1153 # echo 0 > /sys/devices/system/cpu/cpu1/online
1154 bash: echo: write error: Operation not permitted
1156 To compile this code as a module, choose M here: the module will
1157 be called cpu-notifier-error-inject.
1159 If unsure, say N.
1161 config PM_NOTIFIER_ERROR_INJECT
1162 tristate "PM notifier error injection module"
1163 depends on PM && NOTIFIER_ERROR_INJECTION
1164 default m if PM_DEBUG
1165 help
1166 This option provides the ability to inject artificial errors to
1167 PM notifier chain callbacks. It is controlled through debugfs
1168 interface /sys/kernel/debug/notifier-error-inject/pm
1170 If the notifier call chain should be failed with some events
1171 notified, write the error code to "actions/<notifier event>/error".
1173 Example: Inject PM suspend error (-12 = -ENOMEM)
1175 # cd /sys/kernel/debug/notifier-error-inject/pm/
1176 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1177 # echo mem > /sys/power/state
1178 bash: echo: write error: Cannot allocate memory
1180 To compile this code as a module, choose M here: the module will
1181 be called pm-notifier-error-inject.
1183 If unsure, say N.
1185 config MEMORY_NOTIFIER_ERROR_INJECT
1186 tristate "Memory hotplug notifier error injection module"
1187 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1188 help
1189 This option provides the ability to inject artificial errors to
1190 memory hotplug notifier chain callbacks. It is controlled through
1191 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
1193 If the notifier call chain should be failed with some events
1194 notified, write the error code to "actions/<notifier event>/error".
1196 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
1198 # cd /sys/kernel/debug/notifier-error-inject/memory
1199 # echo -12 > actions/MEM_GOING_OFFLINE/error
1200 # echo offline > /sys/devices/system/memory/memoryXXX/state
1201 bash: echo: write error: Cannot allocate memory
1203 To compile this code as a module, choose M here: the module will
1204 be called pSeries-reconfig-notifier-error-inject.
1206 If unsure, say N.
1208 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1209 tristate "OF reconfig notifier error injection module"
1210 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1211 help
1212 This option provides the ability to inject artificial errors to
1213 OF reconfig notifier chain callbacks. It is controlled
1214 through debugfs interface under
1215 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1217 If the notifier call chain should be failed with some events
1218 notified, write the error code to "actions/<notifier event>/error".
1220 To compile this code as a module, choose M here: the module will
1221 be called memory-notifier-error-inject.
1223 If unsure, say N.
1225 config FAULT_INJECTION
1226 bool "Fault-injection framework"
1227 depends on DEBUG_KERNEL
1228 help
1229 Provide fault-injection framework.
1230 For more details, see Documentation/fault-injection/.
1232 config FAILSLAB
1233 bool "Fault-injection capability for kmalloc"
1234 depends on FAULT_INJECTION
1235 depends on SLAB || SLUB
1236 help
1237 Provide fault-injection capability for kmalloc.
1239 config FAIL_PAGE_ALLOC
1240 bool "Fault-injection capabilitiy for alloc_pages()"
1241 depends on FAULT_INJECTION
1242 help
1243 Provide fault-injection capability for alloc_pages().
1245 config FAIL_MAKE_REQUEST
1246 bool "Fault-injection capability for disk IO"
1247 depends on FAULT_INJECTION && BLOCK
1248 help
1249 Provide fault-injection capability for disk IO.
1251 config FAIL_IO_TIMEOUT
1252 bool "Fault-injection capability for faking disk interrupts"
1253 depends on FAULT_INJECTION && BLOCK
1254 help
1255 Provide fault-injection capability on end IO handling. This
1256 will make the block layer "forget" an interrupt as configured,
1257 thus exercising the error handling.
1259 Only works with drivers that use the generic timeout handling,
1260 for others it wont do anything.
1262 config FAIL_MMC_REQUEST
1263 bool "Fault-injection capability for MMC IO"
1264 select DEBUG_FS
1265 depends on FAULT_INJECTION && MMC
1266 help
1267 Provide fault-injection capability for MMC IO.
1268 This will make the mmc core return data errors. This is
1269 useful to test the error handling in the mmc block device
1270 and to test how the mmc host driver handles retries from
1271 the block device.
1273 config FAULT_INJECTION_DEBUG_FS
1274 bool "Debugfs entries for fault-injection capabilities"
1275 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1276 help
1277 Enable configuration of fault-injection capabilities via debugfs.
1279 config FAULT_INJECTION_STACKTRACE_FILTER
1280 bool "stacktrace filter for fault-injection capabilities"
1281 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1282 depends on !X86_64
1283 select STACKTRACE
1284 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1285 help
1286 Provide stacktrace filter for fault-injection capabilities
1288 config LATENCYTOP
1289 bool "Latency measuring infrastructure"
1290 depends on HAVE_LATENCYTOP_SUPPORT
1291 depends on DEBUG_KERNEL
1292 depends on STACKTRACE_SUPPORT
1293 depends on PROC_FS
1294 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1295 select KALLSYMS
1296 select KALLSYMS_ALL
1297 select STACKTRACE
1298 select SCHEDSTATS
1299 select SCHED_DEBUG
1300 help
1301 Enable this option if you want to use the LatencyTOP tool
1302 to find out which userspace is blocking on what kernel operations.
1304 source mm/Kconfig.debug
1305 source kernel/trace/Kconfig
1307 config RBTREE_TEST
1308 tristate "Red-Black tree test"
1309 depends on m && DEBUG_KERNEL
1310 help
1311 A benchmark measuring the performance of the rbtree library.
1312 Also includes rbtree invariant checks.
1314 config INTERVAL_TREE_TEST
1315 tristate "Interval tree test"
1316 depends on m && DEBUG_KERNEL
1317 help
1318 A benchmark measuring the performance of the interval tree library
1320 config PROVIDE_OHCI1394_DMA_INIT
1321 bool "Remote debugging over FireWire early on boot"
1322 depends on PCI && X86
1323 help
1324 If you want to debug problems which hang or crash the kernel early
1325 on boot and the crashing machine has a FireWire port, you can use
1326 this feature to remotely access the memory of the crashed machine
1327 over FireWire. This employs remote DMA as part of the OHCI1394
1328 specification which is now the standard for FireWire controllers.
1330 With remote DMA, you can monitor the printk buffer remotely using
1331 firescope and access all memory below 4GB using fireproxy from gdb.
1332 Even controlling a kernel debugger is possible using remote DMA.
1334 Usage:
1336 If ohci1394_dma=early is used as boot parameter, it will initialize
1337 all OHCI1394 controllers which are found in the PCI config space.
1339 As all changes to the FireWire bus such as enabling and disabling
1340 devices cause a bus reset and thereby disable remote DMA for all
1341 devices, be sure to have the cable plugged and FireWire enabled on
1342 the debugging host before booting the debug target for debugging.
1344 This code (~1k) is freed after boot. By then, the firewire stack
1345 in charge of the OHCI-1394 controllers should be used instead.
1347 See Documentation/debugging-via-ohci1394.txt for more information.
1349 config FIREWIRE_OHCI_REMOTE_DMA
1350 bool "Remote debugging over FireWire with firewire-ohci"
1351 depends on FIREWIRE_OHCI
1352 help
1353 This option lets you use the FireWire bus for remote debugging
1354 with help of the firewire-ohci driver. It enables unfiltered
1355 remote DMA in firewire-ohci.
1356 See Documentation/debugging-via-ohci1394.txt for more information.
1358 If unsure, say N.
1360 config BUILD_DOCSRC
1361 bool "Build targets in Documentation/ tree"
1362 depends on HEADERS_CHECK
1363 help
1364 This option attempts to build objects from the source files in the
1365 kernel Documentation/ tree.
1367 Say N if you are unsure.
1369 config DYNAMIC_DEBUG
1370 bool "Enable dynamic printk() support"
1371 default n
1372 depends on PRINTK
1373 depends on DEBUG_FS
1374 help
1376 Compiles debug level messages into the kernel, which would not
1377 otherwise be available at runtime. These messages can then be
1378 enabled/disabled based on various levels of scope - per source file,
1379 function, module, format string, and line number. This mechanism
1380 implicitly compiles in all pr_debug() and dev_dbg() calls, which
1381 enlarges the kernel text size by about 2%.
1383 If a source file is compiled with DEBUG flag set, any
1384 pr_debug() calls in it are enabled by default, but can be
1385 disabled at runtime as below. Note that DEBUG flag is
1386 turned on by many CONFIG_*DEBUG* options.
1388 Usage:
1390 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1391 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1392 filesystem must first be mounted before making use of this feature.
1393 We refer the control file as: <debugfs>/dynamic_debug/control. This
1394 file contains a list of the debug statements that can be enabled. The
1395 format for each line of the file is:
1397 filename:lineno [module]function flags format
1399 filename : source file of the debug statement
1400 lineno : line number of the debug statement
1401 module : module that contains the debug statement
1402 function : function that contains the debug statement
1403 flags : '=p' means the line is turned 'on' for printing
1404 format : the format used for the debug statement
1406 From a live system:
1408 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1409 # filename:lineno [module]function flags format
1410 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1411 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1412 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
1414 Example usage:
1416 // enable the message at line 1603 of file svcsock.c
1417 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1418 <debugfs>/dynamic_debug/control
1420 // enable all the messages in file svcsock.c
1421 nullarbor:~ # echo -n 'file svcsock.c +p' >
1422 <debugfs>/dynamic_debug/control
1424 // enable all the messages in the NFS server module
1425 nullarbor:~ # echo -n 'module nfsd +p' >
1426 <debugfs>/dynamic_debug/control
1428 // enable all 12 messages in the function svc_process()
1429 nullarbor:~ # echo -n 'func svc_process +p' >
1430 <debugfs>/dynamic_debug/control
1432 // disable all 12 messages in the function svc_process()
1433 nullarbor:~ # echo -n 'func svc_process -p' >
1434 <debugfs>/dynamic_debug/control
1436 See Documentation/dynamic-debug-howto.txt for additional information.
1438 config DMA_API_DEBUG
1439 bool "Enable debugging of DMA-API usage"
1440 depends on HAVE_DMA_API_DEBUG
1441 help
1442 Enable this option to debug the use of the DMA API by device drivers.
1443 With this option you will be able to detect common bugs in device
1444 drivers like double-freeing of DMA mappings or freeing mappings that
1445 were never allocated.
1446 This option causes a performance degredation. Use only if you want
1447 to debug device drivers. If unsure, say N.
1449 config ATOMIC64_SELFTEST
1450 bool "Perform an atomic64_t self-test at boot"
1451 help
1452 Enable this option to test the atomic64_t functions at boot.
1454 If unsure, say N.
1456 config ASYNC_RAID6_TEST
1457 tristate "Self test for hardware accelerated raid6 recovery"
1458 depends on ASYNC_RAID6_RECOV
1459 select ASYNC_MEMCPY
1460 ---help---
1461 This is a one-shot self test that permutes through the
1462 recovery of all the possible two disk failure scenarios for a
1463 N-disk array. Recovery is performed with the asynchronous
1464 raid6 recovery routines, and will optionally use an offload
1465 engine if one is available.
1467 If unsure, say N.
1469 source "samples/Kconfig"
1471 source "lib/Kconfig.kgdb"
1473 source "lib/Kconfig.kmemcheck"
1475 config TEST_KSTRTOX
1476 tristate "Test kstrto*() family of functions at runtime"