Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
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linux
1
2config PRINTK_TIME
3 bool "Show timing information on printks"
4 depends on PRINTK
5 help
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
10 in kernel startup.
11
12config ENABLE_WARN_DEPRECATED
13 bool "Enable __deprecated logic"
14 default y
15 help
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.
19
20config ENABLE_MUST_CHECK
21 bool "Enable __must_check logic"
22 default y
23 help
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.
27
28config FRAME_WARN
29 int "Warn for stack frames larger than (needs gcc 4.4)"
30 range 0 8192
31 default 1024 if !64BIT
32 default 2048 if 64BIT
33 help
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.
37 Requires gcc 4.4
38
39config MAGIC_SYSRQ
40 bool "Magic SysRq key"
41 depends on !UML
42 help
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.
52
53config UNUSED_SYMBOLS
54 bool "Enable unused/obsolete exported symbols"
55 default y if X86
56 help
57 Unused but exported symbols make the kernel needlessly bigger. For
58 that reason most of these unused exports will soon be removed. This
59 option is provided temporarily to provide a transition period in case
60 some external kernel module needs one of these symbols anyway. If you
61 encounter such a case in your module, consider if you are actually
62 using the right API. (rationale: since nobody in the kernel is using
63 this in a module, there is a pretty good chance it's actually the
64 wrong interface to use). If you really need the symbol, please send a
65 mail to the linux kernel mailing list mentioning the symbol and why
66 you really need it, and what the merge plan to the mainline kernel for
67 your module is.
68
69config DEBUG_FS
70 bool "Debug Filesystem"
71 depends on SYSFS
72 help
73 debugfs is a virtual file system that kernel developers use to put
74 debugging files into. Enable this option to be able to read and
75 write to these files.
76
77 For detailed documentation on the debugfs API, see
78 Documentation/DocBook/filesystems.
79
80 If unsure, say N.
81
82config HEADERS_CHECK
83 bool "Run 'make headers_check' when building vmlinux"
84 depends on !UML
85 help
86 This option will extract the user-visible kernel headers whenever
87 building the kernel, and will run basic sanity checks on them to
88 ensure that exported files do not attempt to include files which
89 were not exported, etc.
90
91 If you're making modifications to header files which are
92 relevant for userspace, say 'Y', and check the headers
93 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
94 your build tree), to make sure they're suitable.
95
96config DEBUG_SECTION_MISMATCH
97 bool "Enable full Section mismatch analysis"
98 depends on UNDEFINED
99 # This option is on purpose disabled for now.
100 # It will be enabled when we are down to a resonable number
101 # of section mismatch warnings (< 10 for an allyesconfig build)
102 help
103 The section mismatch analysis checks if there are illegal
104 references from one section to another section.
105 Linux will during link or during runtime drop some sections
106 and any use of code/data previously in these sections will
107 most likely result in an oops.
108 In the code functions and variables are annotated with
109 __init, __devinit etc. (see full list in include/linux/init.h)
110 which results in the code/data being placed in specific sections.
111 The section mismatch analysis is always done after a full
112 kernel build but enabling this option will in addition
113 do the following:
114 - Add the option -fno-inline-functions-called-once to gcc
115 When inlining a function annotated __init in a non-init
116 function we would lose the section information and thus
117 the analysis would not catch the illegal reference.
118 This option tells gcc to inline less but will also
119 result in a larger kernel.
120 - Run the section mismatch analysis for each module/built-in.o
121 When we run the section mismatch analysis on vmlinux.o we
122 lose valueble information about where the mismatch was
123 introduced.
124 Running the analysis for each module/built-in.o file
125 will tell where the mismatch happens much closer to the
126 source. The drawback is that we will report the same
127 mismatch at least twice.
128 - Enable verbose reporting from modpost to help solving
129 the section mismatches reported.
130
131config DEBUG_KERNEL
132 bool "Kernel debugging"
133 help
134 Say Y here if you are developing drivers or trying to debug and
135 identify kernel problems.
136
137config DEBUG_SHIRQ
138 bool "Debug shared IRQ handlers"
139 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
140 help
141 Enable this to generate a spurious interrupt as soon as a shared
142 interrupt handler is registered, and just before one is deregistered.
143 Drivers ought to be able to handle interrupts coming in at those
144 points; some don't and need to be caught.
145
146config DETECT_SOFTLOCKUP
147 bool "Detect Soft Lockups"
148 depends on DEBUG_KERNEL && !S390
149 default y
150 help
151 Say Y here to enable the kernel to detect "soft lockups",
152 which are bugs that cause the kernel to loop in kernel
153 mode for more than 60 seconds, without giving other tasks a
154 chance to run.
155
156 When a soft-lockup is detected, the kernel will print the
157 current stack trace (which you should report), but the
158 system will stay locked up. This feature has negligible
159 overhead.
160
161 (Note that "hard lockups" are separate type of bugs that
162 can be detected via the NMI-watchdog, on platforms that
163 support it.)
164
165config BOOTPARAM_SOFTLOCKUP_PANIC
166 bool "Panic (Reboot) On Soft Lockups"
167 depends on DETECT_SOFTLOCKUP
168 help
169 Say Y here to enable the kernel to panic on "soft lockups",
170 which are bugs that cause the kernel to loop in kernel
171 mode for more than 60 seconds, without giving other tasks a
172 chance to run.
173
174 The panic can be used in combination with panic_timeout,
175 to cause the system to reboot automatically after a
176 lockup has been detected. This feature is useful for
177 high-availability systems that have uptime guarantees and
178 where a lockup must be resolved ASAP.
179
180 Say N if unsure.
181
182config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
183 int
184 depends on DETECT_SOFTLOCKUP
185 range 0 1
186 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
187 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
188
189config DETECT_HUNG_TASK
190 bool "Detect Hung Tasks"
191 depends on DEBUG_KERNEL
192 default DETECT_SOFTLOCKUP
193 help
194 Say Y here to enable the kernel to detect "hung tasks",
195 which are bugs that cause the task to be stuck in
196 uninterruptible "D" state indefinitiley.
197
198 When a hung task is detected, the kernel will print the
199 current stack trace (which you should report), but the
200 task will stay in uninterruptible state. If lockdep is
201 enabled then all held locks will also be reported. This
202 feature has negligible overhead.
203
204config BOOTPARAM_HUNG_TASK_PANIC
205 bool "Panic (Reboot) On Hung Tasks"
206 depends on DETECT_HUNG_TASK
207 help
208 Say Y here to enable the kernel to panic on "hung tasks",
209 which are bugs that cause the kernel to leave a task stuck
210 in uninterruptible "D" state.
211
212 The panic can be used in combination with panic_timeout,
213 to cause the system to reboot automatically after a
214 hung task has been detected. This feature is useful for
215 high-availability systems that have uptime guarantees and
216 where a hung tasks must be resolved ASAP.
217
218 Say N if unsure.
219
220config BOOTPARAM_HUNG_TASK_PANIC_VALUE
221 int
222 depends on DETECT_HUNG_TASK
223 range 0 1
224 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
225 default 1 if BOOTPARAM_HUNG_TASK_PANIC
226
227config SCHED_DEBUG
228 bool "Collect scheduler debugging info"
229 depends on DEBUG_KERNEL && PROC_FS
230 default y
231 help
232 If you say Y here, the /proc/sched_debug file will be provided
233 that can help debug the scheduler. The runtime overhead of this
234 option is minimal.
235
236config SCHEDSTATS
237 bool "Collect scheduler statistics"
238 depends on DEBUG_KERNEL && PROC_FS
239 help
240 If you say Y here, additional code will be inserted into the
241 scheduler and related routines to collect statistics about
242 scheduler behavior and provide them in /proc/schedstat. These
243 stats may be useful for both tuning and debugging the scheduler
244 If you aren't debugging the scheduler or trying to tune a specific
245 application, you can say N to avoid the very slight overhead
246 this adds.
247
248config TIMER_STATS
249 bool "Collect kernel timers statistics"
250 depends on DEBUG_KERNEL && PROC_FS
251 help
252 If you say Y here, additional code will be inserted into the
253 timer routines to collect statistics about kernel timers being
254 reprogrammed. The statistics can be read from /proc/timer_stats.
255 The statistics collection is started by writing 1 to /proc/timer_stats,
256 writing 0 stops it. This feature is useful to collect information
257 about timer usage patterns in kernel and userspace. This feature
258 is lightweight if enabled in the kernel config but not activated
259 (it defaults to deactivated on bootup and will only be activated
260 if some application like powertop activates it explicitly).
261
262config DEBUG_OBJECTS
263 bool "Debug object operations"
264 depends on DEBUG_KERNEL
265 help
266 If you say Y here, additional code will be inserted into the
267 kernel to track the life time of various objects and validate
268 the operations on those objects.
269
270config DEBUG_OBJECTS_SELFTEST
271 bool "Debug objects selftest"
272 depends on DEBUG_OBJECTS
273 help
274 This enables the selftest of the object debug code.
275
276config DEBUG_OBJECTS_FREE
277 bool "Debug objects in freed memory"
278 depends on DEBUG_OBJECTS
279 help
280 This enables checks whether a k/v free operation frees an area
281 which contains an object which has not been deactivated
282 properly. This can make kmalloc/kfree-intensive workloads
283 much slower.
284
285config DEBUG_OBJECTS_TIMERS
286 bool "Debug timer objects"
287 depends on DEBUG_OBJECTS
288 help
289 If you say Y here, additional code will be inserted into the
290 timer routines to track the life time of timer objects and
291 validate the timer operations.
292
293config DEBUG_OBJECTS_ENABLE_DEFAULT
294 int "debug_objects bootup default value (0-1)"
295 range 0 1
296 default "1"
297 depends on DEBUG_OBJECTS
298 help
299 Debug objects boot parameter default value
300
301config DEBUG_SLAB
302 bool "Debug slab memory allocations"
303 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
304 help
305 Say Y here to have the kernel do limited verification on memory
306 allocation as well as poisoning memory on free to catch use of freed
307 memory. This can make kmalloc/kfree-intensive workloads much slower.
308
309config DEBUG_SLAB_LEAK
310 bool "Memory leak debugging"
311 depends on DEBUG_SLAB
312
313config SLUB_DEBUG_ON
314 bool "SLUB debugging on by default"
315 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
316 default n
317 help
318 Boot with debugging on by default. SLUB boots by default with
319 the runtime debug capabilities switched off. Enabling this is
320 equivalent to specifying the "slub_debug" parameter on boot.
321 There is no support for more fine grained debug control like
322 possible with slub_debug=xxx. SLUB debugging may be switched
323 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
324 "slub_debug=-".
325
326config SLUB_STATS
327 default n
328 bool "Enable SLUB performance statistics"
329 depends on SLUB && SLUB_DEBUG && SYSFS
330 help
331 SLUB statistics are useful to debug SLUBs allocation behavior in
332 order find ways to optimize the allocator. This should never be
333 enabled for production use since keeping statistics slows down
334 the allocator by a few percentage points. The slabinfo command
335 supports the determination of the most active slabs to figure
336 out which slabs are relevant to a particular load.
337 Try running: slabinfo -DA
338
339config DEBUG_KMEMLEAK
340 bool "Kernel memory leak detector"
341 depends on DEBUG_KERNEL && EXPERIMENTAL && (X86 || ARM) && \
342 !MEMORY_HOTPLUG
343 select DEBUG_FS if SYSFS
344 select STACKTRACE if STACKTRACE_SUPPORT
345 select KALLSYMS
346 help
347 Say Y here if you want to enable the memory leak
348 detector. The memory allocation/freeing is traced in a way
349 similar to the Boehm's conservative garbage collector, the
350 difference being that the orphan objects are not freed but
351 only shown in /sys/kernel/debug/kmemleak. Enabling this
352 feature will introduce an overhead to memory
353 allocations. See Documentation/kmemleak.txt for more
354 details.
355
356 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
357 of finding leaks due to the slab objects poisoning.
358
359 In order to access the kmemleak file, debugfs needs to be
360 mounted (usually at /sys/kernel/debug).
361
362config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
363 int "Maximum kmemleak early log entries"
364 depends on DEBUG_KMEMLEAK
365 range 200 2000
366 default 400
367 help
368 Kmemleak must track all the memory allocations to avoid
369 reporting false positives. Since memory may be allocated or
370 freed before kmemleak is initialised, an early log buffer is
371 used to store these actions. If kmemleak reports "early log
372 buffer exceeded", please increase this value.
373
374config DEBUG_KMEMLEAK_TEST
375 tristate "Simple test for the kernel memory leak detector"
376 depends on DEBUG_KMEMLEAK
377 help
378 Say Y or M here to build a test for the kernel memory leak
379 detector. This option enables a module that explicitly leaks
380 memory.
381
382 If unsure, say N.
383
384config DEBUG_PREEMPT
385 bool "Debug preemptible kernel"
386 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
387 default y
388 help
389 If you say Y here then the kernel will use a debug variant of the
390 commonly used smp_processor_id() function and will print warnings
391 if kernel code uses it in a preemption-unsafe way. Also, the kernel
392 will detect preemption count underflows.
393
394config DEBUG_RT_MUTEXES
395 bool "RT Mutex debugging, deadlock detection"
396 depends on DEBUG_KERNEL && RT_MUTEXES
397 help
398 This allows rt mutex semantics violations and rt mutex related
399 deadlocks (lockups) to be detected and reported automatically.
400
401config DEBUG_PI_LIST
402 bool
403 default y
404 depends on DEBUG_RT_MUTEXES
405
406config RT_MUTEX_TESTER
407 bool "Built-in scriptable tester for rt-mutexes"
408 depends on DEBUG_KERNEL && RT_MUTEXES
409 help
410 This option enables a rt-mutex tester.
411
412config DEBUG_SPINLOCK
413 bool "Spinlock and rw-lock debugging: basic checks"
414 depends on DEBUG_KERNEL
415 help
416 Say Y here and build SMP to catch missing spinlock initialization
417 and certain other kinds of spinlock errors commonly made. This is
418 best used in conjunction with the NMI watchdog so that spinlock
419 deadlocks are also debuggable.
420
421config DEBUG_MUTEXES
422 bool "Mutex debugging: basic checks"
423 depends on DEBUG_KERNEL
424 help
425 This feature allows mutex semantics violations to be detected and
426 reported.
427
428config DEBUG_LOCK_ALLOC
429 bool "Lock debugging: detect incorrect freeing of live locks"
430 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
431 select DEBUG_SPINLOCK
432 select DEBUG_MUTEXES
433 select LOCKDEP
434 help
435 This feature will check whether any held lock (spinlock, rwlock,
436 mutex or rwsem) is incorrectly freed by the kernel, via any of the
437 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
438 vfree(), etc.), whether a live lock is incorrectly reinitialized via
439 spin_lock_init()/mutex_init()/etc., or whether there is any lock
440 held during task exit.
441
442config PROVE_LOCKING
443 bool "Lock debugging: prove locking correctness"
444 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
445 select LOCKDEP
446 select DEBUG_SPINLOCK
447 select DEBUG_MUTEXES
448 select DEBUG_LOCK_ALLOC
449 default n
450 help
451 This feature enables the kernel to prove that all locking
452 that occurs in the kernel runtime is mathematically
453 correct: that under no circumstance could an arbitrary (and
454 not yet triggered) combination of observed locking
455 sequences (on an arbitrary number of CPUs, running an
456 arbitrary number of tasks and interrupt contexts) cause a
457 deadlock.
458
459 In short, this feature enables the kernel to report locking
460 related deadlocks before they actually occur.
461
462 The proof does not depend on how hard and complex a
463 deadlock scenario would be to trigger: how many
464 participant CPUs, tasks and irq-contexts would be needed
465 for it to trigger. The proof also does not depend on
466 timing: if a race and a resulting deadlock is possible
467 theoretically (no matter how unlikely the race scenario
468 is), it will be proven so and will immediately be
469 reported by the kernel (once the event is observed that
470 makes the deadlock theoretically possible).
471
472 If a deadlock is impossible (i.e. the locking rules, as
473 observed by the kernel, are mathematically correct), the
474 kernel reports nothing.
475
476 NOTE: this feature can also be enabled for rwlocks, mutexes
477 and rwsems - in which case all dependencies between these
478 different locking variants are observed and mapped too, and
479 the proof of observed correctness is also maintained for an
480 arbitrary combination of these separate locking variants.
481
482 For more details, see Documentation/lockdep-design.txt.
483
484config LOCKDEP
485 bool
486 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
487 select STACKTRACE
488 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
489 select KALLSYMS
490 select KALLSYMS_ALL
491
492config LOCK_STAT
493 bool "Lock usage statistics"
494 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
495 select LOCKDEP
496 select DEBUG_SPINLOCK
497 select DEBUG_MUTEXES
498 select DEBUG_LOCK_ALLOC
499 default n
500 help
501 This feature enables tracking lock contention points
502
503 For more details, see Documentation/lockstat.txt
504
505config DEBUG_LOCKDEP
506 bool "Lock dependency engine debugging"
507 depends on DEBUG_KERNEL && LOCKDEP
508 help
509 If you say Y here, the lock dependency engine will do
510 additional runtime checks to debug itself, at the price
511 of more runtime overhead.
512
513config TRACE_IRQFLAGS
514 depends on DEBUG_KERNEL
515 bool
516 default y
517 depends on TRACE_IRQFLAGS_SUPPORT
518 depends on PROVE_LOCKING
519
520config DEBUG_SPINLOCK_SLEEP
521 bool "Spinlock debugging: sleep-inside-spinlock checking"
522 depends on DEBUG_KERNEL
523 help
524 If you say Y here, various routines which may sleep will become very
525 noisy if they are called with a spinlock held.
526
527config DEBUG_LOCKING_API_SELFTESTS
528 bool "Locking API boot-time self-tests"
529 depends on DEBUG_KERNEL
530 help
531 Say Y here if you want the kernel to run a short self-test during
532 bootup. The self-test checks whether common types of locking bugs
533 are detected by debugging mechanisms or not. (if you disable
534 lock debugging then those bugs wont be detected of course.)
535 The following locking APIs are covered: spinlocks, rwlocks,
536 mutexes and rwsems.
537
538config STACKTRACE
539 bool
540 depends on STACKTRACE_SUPPORT
541
542config DEBUG_KOBJECT
543 bool "kobject debugging"
544 depends on DEBUG_KERNEL
545 help
546 If you say Y here, some extra kobject debugging messages will be sent
547 to the syslog.
548
549config DEBUG_HIGHMEM
550 bool "Highmem debugging"
551 depends on DEBUG_KERNEL && HIGHMEM
552 help
553 This options enables addition error checking for high memory systems.
554 Disable for production systems.
555
556config DEBUG_BUGVERBOSE
557 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
558 depends on BUG
559 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
560 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
561 default !EMBEDDED
562 help
563 Say Y here to make BUG() panics output the file name and line number
564 of the BUG call as well as the EIP and oops trace. This aids
565 debugging but costs about 70-100K of memory.
566
567config DEBUG_INFO
568 bool "Compile the kernel with debug info"
569 depends on DEBUG_KERNEL
570 help
571 If you say Y here the resulting kernel image will include
572 debugging info resulting in a larger kernel image.
573 This adds debug symbols to the kernel and modules (gcc -g), and
574 is needed if you intend to use kernel crashdump or binary object
575 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
576 Say Y here only if you plan to debug the kernel.
577
578 If unsure, say N.
579
580config DEBUG_VM
581 bool "Debug VM"
582 depends on DEBUG_KERNEL
583 help
584 Enable this to turn on extended checks in the virtual-memory system
585 that may impact performance.
586
587 If unsure, say N.
588
589config DEBUG_VIRTUAL
590 bool "Debug VM translations"
591 depends on DEBUG_KERNEL && X86
592 help
593 Enable some costly sanity checks in virtual to page code. This can
594 catch mistakes with virt_to_page() and friends.
595
596 If unsure, say N.
597
598config DEBUG_NOMMU_REGIONS
599 bool "Debug the global anon/private NOMMU mapping region tree"
600 depends on DEBUG_KERNEL && !MMU
601 help
602 This option causes the global tree of anonymous and private mapping
603 regions to be regularly checked for invalid topology.
604
605config DEBUG_WRITECOUNT
606 bool "Debug filesystem writers count"
607 depends on DEBUG_KERNEL
608 help
609 Enable this to catch wrong use of the writers count in struct
610 vfsmount. This will increase the size of each file struct by
611 32 bits.
612
613 If unsure, say N.
614
615config DEBUG_MEMORY_INIT
616 bool "Debug memory initialisation" if EMBEDDED
617 default !EMBEDDED
618 help
619 Enable this for additional checks during memory initialisation.
620 The sanity checks verify aspects of the VM such as the memory model
621 and other information provided by the architecture. Verbose
622 information will be printed at KERN_DEBUG loglevel depending
623 on the mminit_loglevel= command-line option.
624
625 If unsure, say Y
626
627config DEBUG_LIST
628 bool "Debug linked list manipulation"
629 depends on DEBUG_KERNEL
630 help
631 Enable this to turn on extended checks in the linked-list
632 walking routines.
633
634 If unsure, say N.
635
636config DEBUG_SG
637 bool "Debug SG table operations"
638 depends on DEBUG_KERNEL
639 help
640 Enable this to turn on checks on scatter-gather tables. This can
641 help find problems with drivers that do not properly initialize
642 their sg tables.
643
644 If unsure, say N.
645
646config DEBUG_NOTIFIERS
647 bool "Debug notifier call chains"
648 depends on DEBUG_KERNEL
649 help
650 Enable this to turn on sanity checking for notifier call chains.
651 This is most useful for kernel developers to make sure that
652 modules properly unregister themselves from notifier chains.
653 This is a relatively cheap check but if you care about maximum
654 performance, say N.
655
656#
657# Select this config option from the architecture Kconfig, if it
658# it is preferred to always offer frame pointers as a config
659# option on the architecture (regardless of KERNEL_DEBUG):
660#
661config ARCH_WANT_FRAME_POINTERS
662 bool
663 help
664
665config FRAME_POINTER
666 bool "Compile the kernel with frame pointers"
667 depends on DEBUG_KERNEL && \
668 (CRIS || M68K || M68KNOMMU || FRV || UML || \
669 AVR32 || SUPERH || BLACKFIN || MN10300) || \
670 ARCH_WANT_FRAME_POINTERS
671 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
672 help
673 If you say Y here the resulting kernel image will be slightly
674 larger and slower, but it gives very useful debugging information
675 in case of kernel bugs. (precise oopses/stacktraces/warnings)
676
677config BOOT_PRINTK_DELAY
678 bool "Delay each boot printk message by N milliseconds"
679 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
680 help
681 This build option allows you to read kernel boot messages
682 by inserting a short delay after each one. The delay is
683 specified in milliseconds on the kernel command line,
684 using "boot_delay=N".
685
686 It is likely that you would also need to use "lpj=M" to preset
687 the "loops per jiffie" value.
688 See a previous boot log for the "lpj" value to use for your
689 system, and then set "lpj=M" before setting "boot_delay=N".
690 NOTE: Using this option may adversely affect SMP systems.
691 I.e., processors other than the first one may not boot up.
692 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
693 what it believes to be lockup conditions.
694
695config RCU_TORTURE_TEST
696 tristate "torture tests for RCU"
697 depends on DEBUG_KERNEL
698 default n
699 help
700 This option provides a kernel module that runs torture tests
701 on the RCU infrastructure. The kernel module may be built
702 after the fact on the running kernel to be tested, if desired.
703
704 Say Y here if you want RCU torture tests to be built into
705 the kernel.
706 Say M if you want the RCU torture tests to build as a module.
707 Say N if you are unsure.
708
709config RCU_TORTURE_TEST_RUNNABLE
710 bool "torture tests for RCU runnable by default"
711 depends on RCU_TORTURE_TEST = y
712 default n
713 help
714 This option provides a way to build the RCU torture tests
715 directly into the kernel without them starting up at boot
716 time. You can use /proc/sys/kernel/rcutorture_runnable
717 to manually override this setting. This /proc file is
718 available only when the RCU torture tests have been built
719 into the kernel.
720
721 Say Y here if you want the RCU torture tests to start during
722 boot (you probably don't).
723 Say N here if you want the RCU torture tests to start only
724 after being manually enabled via /proc.
725
726config RCU_CPU_STALL_DETECTOR
727 bool "Check for stalled CPUs delaying RCU grace periods"
728 depends on CLASSIC_RCU || TREE_RCU
729 default n
730 help
731 This option causes RCU to printk information on which
732 CPUs are delaying the current grace period, but only when
733 the grace period extends for excessive time periods.
734
735 Say Y if you want RCU to perform such checks.
736
737 Say N if you are unsure.
738
739config KPROBES_SANITY_TEST
740 bool "Kprobes sanity tests"
741 depends on DEBUG_KERNEL
742 depends on KPROBES
743 default n
744 help
745 This option provides for testing basic kprobes functionality on
746 boot. A sample kprobe, jprobe and kretprobe are inserted and
747 verified for functionality.
748
749 Say N if you are unsure.
750
751config BACKTRACE_SELF_TEST
752 tristate "Self test for the backtrace code"
753 depends on DEBUG_KERNEL
754 default n
755 help
756 This option provides a kernel module that can be used to test
757 the kernel stack backtrace code. This option is not useful
758 for distributions or general kernels, but only for kernel
759 developers working on architecture code.
760
761 Note that if you want to also test saved backtraces, you will
762 have to enable STACKTRACE as well.
763
764 Say N if you are unsure.
765
766config DEBUG_BLOCK_EXT_DEVT
767 bool "Force extended block device numbers and spread them"
768 depends on DEBUG_KERNEL
769 depends on BLOCK
770 default n
771 help
772 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
773 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
774 YOU ARE DOING. Distros, please enable this and fix whatever
775 is broken.
776
777 Conventionally, block device numbers are allocated from
778 predetermined contiguous area. However, extended block area
779 may introduce non-contiguous block device numbers. This
780 option forces most block device numbers to be allocated from
781 the extended space and spreads them to discover kernel or
782 userland code paths which assume predetermined contiguous
783 device number allocation.
784
785 Note that turning on this debug option shuffles all the
786 device numbers for all IDE and SCSI devices including libata
787 ones, so root partition specified using device number
788 directly (via rdev or root=MAJ:MIN) won't work anymore.
789 Textual device names (root=/dev/sdXn) will continue to work.
790
791 Say N if you are unsure.
792
793config LKDTM
794 tristate "Linux Kernel Dump Test Tool Module"
795 depends on DEBUG_KERNEL
796 depends on KPROBES
797 depends on BLOCK
798 default n
799 help
800 This module enables testing of the different dumping mechanisms by
801 inducing system failures at predefined crash points.
802 If you don't need it: say N
803 Choose M here to compile this code as a module. The module will be
804 called lkdtm.
805
806 Documentation on how to use the module can be found in
807 drivers/misc/lkdtm.c
808
809config FAULT_INJECTION
810 bool "Fault-injection framework"
811 depends on DEBUG_KERNEL
812 help
813 Provide fault-injection framework.
814 For more details, see Documentation/fault-injection/.
815
816config FAILSLAB
817 bool "Fault-injection capability for kmalloc"
818 depends on FAULT_INJECTION
819 depends on SLAB || SLUB
820 help
821 Provide fault-injection capability for kmalloc.
822
823config FAIL_PAGE_ALLOC
824 bool "Fault-injection capabilitiy for alloc_pages()"
825 depends on FAULT_INJECTION
826 help
827 Provide fault-injection capability for alloc_pages().
828
829config FAIL_MAKE_REQUEST
830 bool "Fault-injection capability for disk IO"
831 depends on FAULT_INJECTION && BLOCK
832 help
833 Provide fault-injection capability for disk IO.
834
835config FAIL_IO_TIMEOUT
836 bool "Faul-injection capability for faking disk interrupts"
837 depends on FAULT_INJECTION && BLOCK
838 help
839 Provide fault-injection capability on end IO handling. This
840 will make the block layer "forget" an interrupt as configured,
841 thus exercising the error handling.
842
843 Only works with drivers that use the generic timeout handling,
844 for others it wont do anything.
845
846config FAULT_INJECTION_DEBUG_FS
847 bool "Debugfs entries for fault-injection capabilities"
848 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
849 help
850 Enable configuration of fault-injection capabilities via debugfs.
851
852config FAULT_INJECTION_STACKTRACE_FILTER
853 bool "stacktrace filter for fault-injection capabilities"
854 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
855 depends on !X86_64
856 select STACKTRACE
857 select FRAME_POINTER if !PPC && !S390
858 help
859 Provide stacktrace filter for fault-injection capabilities
860
861config LATENCYTOP
862 bool "Latency measuring infrastructure"
863 select FRAME_POINTER if !MIPS && !PPC && !S390
864 select KALLSYMS
865 select KALLSYMS_ALL
866 select STACKTRACE
867 select SCHEDSTATS
868 select SCHED_DEBUG
869 depends on HAVE_LATENCYTOP_SUPPORT
870 help
871 Enable this option if you want to use the LatencyTOP tool
872 to find out which userspace is blocking on what kernel operations.
873
874config SYSCTL_SYSCALL_CHECK
875 bool "Sysctl checks"
876 depends on SYSCTL_SYSCALL
877 ---help---
878 sys_sysctl uses binary paths that have been found challenging
879 to properly maintain and use. This enables checks that help
880 you to keep things correct.
881
882source mm/Kconfig.debug
883source kernel/trace/Kconfig
884
885config PROVIDE_OHCI1394_DMA_INIT
886 bool "Remote debugging over FireWire early on boot"
887 depends on PCI && X86
888 help
889 If you want to debug problems which hang or crash the kernel early
890 on boot and the crashing machine has a FireWire port, you can use
891 this feature to remotely access the memory of the crashed machine
892 over FireWire. This employs remote DMA as part of the OHCI1394
893 specification which is now the standard for FireWire controllers.
894
895 With remote DMA, you can monitor the printk buffer remotely using
896 firescope and access all memory below 4GB using fireproxy from gdb.
897 Even controlling a kernel debugger is possible using remote DMA.
898
899 Usage:
900
901 If ohci1394_dma=early is used as boot parameter, it will initialize
902 all OHCI1394 controllers which are found in the PCI config space.
903
904 As all changes to the FireWire bus such as enabling and disabling
905 devices cause a bus reset and thereby disable remote DMA for all
906 devices, be sure to have the cable plugged and FireWire enabled on
907 the debugging host before booting the debug target for debugging.
908
909 This code (~1k) is freed after boot. By then, the firewire stack
910 in charge of the OHCI-1394 controllers should be used instead.
911
912 See Documentation/debugging-via-ohci1394.txt for more information.
913
914config FIREWIRE_OHCI_REMOTE_DMA
915 bool "Remote debugging over FireWire with firewire-ohci"
916 depends on FIREWIRE_OHCI
917 help
918 This option lets you use the FireWire bus for remote debugging
919 with help of the firewire-ohci driver. It enables unfiltered
920 remote DMA in firewire-ohci.
921 See Documentation/debugging-via-ohci1394.txt for more information.
922
923 If unsure, say N.
924
925config BUILD_DOCSRC
926 bool "Build targets in Documentation/ tree"
927 depends on HEADERS_CHECK
928 help
929 This option attempts to build objects from the source files in the
930 kernel Documentation/ tree.
931
932 Say N if you are unsure.
933
934config DYNAMIC_DEBUG
935 bool "Enable dynamic printk() support"
936 default n
937 depends on PRINTK
938 depends on DEBUG_FS
939 help
940
941 Compiles debug level messages into the kernel, which would not
942 otherwise be available at runtime. These messages can then be
943 enabled/disabled based on various levels of scope - per source file,
944 function, module, format string, and line number. This mechanism
945 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
946 this compile option is a larger kernel text size of about 2%.
947
948 Usage:
949
950 Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
951 which is contained in the 'debugfs' filesystem. Thus, the debugfs
952 filesystem must first be mounted before making use of this feature.
953 We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
954 file contains a list of the debug statements that can be enabled. The
955 format for each line of the file is:
956
957 filename:lineno [module]function flags format
958
959 filename : source file of the debug statement
960 lineno : line number of the debug statement
961 module : module that contains the debug statement
962 function : function that contains the debug statement
963 flags : 'p' means the line is turned 'on' for printing
964 format : the format used for the debug statement
965
966 From a live system:
967
968 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
969 # filename:lineno [module]function flags format
970 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
971 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
972 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
973
974 Example usage:
975
976 // enable the message at line 1603 of file svcsock.c
977 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
978 <debugfs>/dynamic_debug/ddebug
979
980 // enable all the messages in file svcsock.c
981 nullarbor:~ # echo -n 'file svcsock.c +p' >
982 <debugfs>/dynamic_debug/ddebug
983
984 // enable all the messages in the NFS server module
985 nullarbor:~ # echo -n 'module nfsd +p' >
986 <debugfs>/dynamic_debug/ddebug
987
988 // enable all 12 messages in the function svc_process()
989 nullarbor:~ # echo -n 'func svc_process +p' >
990 <debugfs>/dynamic_debug/ddebug
991
992 // disable all 12 messages in the function svc_process()
993 nullarbor:~ # echo -n 'func svc_process -p' >
994 <debugfs>/dynamic_debug/ddebug
995
996 See Documentation/dynamic-debug-howto.txt for additional information.
997
998config DMA_API_DEBUG
999 bool "Enable debugging of DMA-API usage"
1000 depends on HAVE_DMA_API_DEBUG
1001 help
1002 Enable this option to debug the use of the DMA API by device drivers.
1003 With this option you will be able to detect common bugs in device
1004 drivers like double-freeing of DMA mappings or freeing mappings that
1005 were never allocated.
1006 This option causes a performance degredation. Use only if you want
1007 to debug device drivers. If unsure, say N.
1008
1009source "samples/Kconfig"
1010
1011source "lib/Kconfig.kgdb"
1012
1013source "lib/Kconfig.kmemcheck"