| blob | 3af91a783c8ae4ce167fa73a91936a94d5d5b4d2 |
2 config 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.
12 config 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.
20 config 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.
28 config 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
39 config 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.
53 config STRIP_ASM_SYMS
54 bool "Strip assembler-generated symbols during link"
55 default n
56 help
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.
61 config UNUSED_SYMBOLS
62 bool "Enable unused/obsolete exported symbols"
63 default y if X86
64 help
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
75 your module is.
77 config DEBUG_FS
78 bool "Debug Filesystem"
79 depends on SYSFS
80 help
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
83 write to these files.
85 For detailed documentation on the debugfs API, see
86 Documentation/DocBook/filesystems.
88 If unsure, say N.
90 config HEADERS_CHECK
91 bool "Run 'make headers_check' when building vmlinux"
92 depends on !UML
93 help
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
107 # This option is on purpose disabled for now.
108 # It will be enabled when we are down to a resonable number
109 # of section mismatch warnings (< 10 for an allyesconfig build)
110 help
111 The section mismatch analysis checks if there are illegal
112 references from one section to another section.
113 Linux will during link or during runtime drop some sections
114 and any use of code/data previously in these sections will
115 most likely result in an oops.
116 In the code functions and variables are annotated with
117 __init, __devinit etc. (see full list in include/linux/init.h)
118 which results in the code/data being placed in specific sections.
119 The section mismatch analysis is always done after a full
120 kernel build but enabling this option will in addition
121 do the following:
122 - Add the option -fno-inline-functions-called-once to gcc
123 When inlining a function annotated __init in a non-init
124 function we would lose the section information and thus
125 the analysis would not catch the illegal reference.
126 This option tells gcc to inline less but will also
127 result in a larger kernel.
128 - Run the section mismatch analysis for each module/built-in.o
129 When we run the section mismatch analysis on vmlinux.o we
130 lose valueble information about where the mismatch was
131 introduced.
132 Running the analysis for each module/built-in.o file
133 will tell where the mismatch happens much closer to the
134 source. The drawback is that we will report the same
135 mismatch at least twice.
136 - Enable verbose reporting from modpost to help solving
137 the section mismatches reported.
139 config DEBUG_KERNEL
140 bool "Kernel debugging"
141 help
142 Say Y here if you are developing drivers or trying to debug and
143 identify kernel problems.
145 config DEBUG_SHIRQ
146 bool "Debug shared IRQ handlers"
147 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
148 help
149 Enable this to generate a spurious interrupt as soon as a shared
150 interrupt handler is registered, and just before one is deregistered.
151 Drivers ought to be able to handle interrupts coming in at those
152 points; some don't and need to be caught.
154 config DETECT_SOFTLOCKUP
155 bool "Detect Soft Lockups"
156 depends on DEBUG_KERNEL && !S390
157 default y
158 help
159 Say Y here to enable the kernel to detect "soft lockups",
160 which are bugs that cause the kernel to loop in kernel
161 mode for more than 60 seconds, without giving other tasks a
162 chance to run.
164 When a soft-lockup is detected, the kernel will print the
165 current stack trace (which you should report), but the
166 system will stay locked up. This feature has negligible
167 overhead.
169 (Note that "hard lockups" are separate type of bugs that
170 can be detected via the NMI-watchdog, on platforms that
171 support it.)
173 config BOOTPARAM_SOFTLOCKUP_PANIC
174 bool "Panic (Reboot) On Soft Lockups"
175 depends on DETECT_SOFTLOCKUP
176 help
177 Say Y here to enable the kernel to panic on "soft lockups",
178 which are bugs that cause the kernel to loop in kernel
179 mode for more than 60 seconds, without giving other tasks a
180 chance to run.
182 The panic can be used in combination with panic_timeout,
183 to cause the system to reboot automatically after a
184 lockup has been detected. This feature is useful for
185 high-availability systems that have uptime guarantees and
186 where a lockup must be resolved ASAP.
188 Say N if unsure.
190 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
191 int
192 depends on DETECT_SOFTLOCKUP
193 range 0 1
194 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
195 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
197 config DETECT_HUNG_TASK
198 bool "Detect Hung Tasks"
199 depends on DEBUG_KERNEL
200 default DETECT_SOFTLOCKUP
201 help
202 Say Y here to enable the kernel to detect "hung tasks",
203 which are bugs that cause the task to be stuck in
204 uninterruptible "D" state indefinitiley.
206 When a hung task is detected, the kernel will print the
207 current stack trace (which you should report), but the
208 task will stay in uninterruptible state. If lockdep is
209 enabled then all held locks will also be reported. This
210 feature has negligible overhead.
212 config BOOTPARAM_HUNG_TASK_PANIC
213 bool "Panic (Reboot) On Hung Tasks"
214 depends on DETECT_HUNG_TASK
215 help
216 Say Y here to enable the kernel to panic on "hung tasks",
217 which are bugs that cause the kernel to leave a task stuck
218 in uninterruptible "D" state.
220 The panic can be used in combination with panic_timeout,
221 to cause the system to reboot automatically after a
222 hung task has been detected. This feature is useful for
223 high-availability systems that have uptime guarantees and
224 where a hung tasks must be resolved ASAP.
226 Say N if unsure.
228 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
229 int
230 depends on DETECT_HUNG_TASK
231 range 0 1
232 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
233 default 1 if BOOTPARAM_HUNG_TASK_PANIC
235 config SCHED_DEBUG
236 bool "Collect scheduler debugging info"
237 depends on DEBUG_KERNEL && PROC_FS
238 default y
239 help
240 If you say Y here, the /proc/sched_debug file will be provided
241 that can help debug the scheduler. The runtime overhead of this
242 option is minimal.
244 config SCHEDSTATS
245 bool "Collect scheduler statistics"
246 depends on DEBUG_KERNEL && PROC_FS
247 help
248 If you say Y here, additional code will be inserted into the
249 scheduler and related routines to collect statistics about
250 scheduler behavior and provide them in /proc/schedstat. These
251 stats may be useful for both tuning and debugging the scheduler
252 If you aren't debugging the scheduler or trying to tune a specific
253 application, you can say N to avoid the very slight overhead
254 this adds.
256 config TIMER_STATS
257 bool "Collect kernel timers statistics"
258 depends on DEBUG_KERNEL && PROC_FS
259 help
260 If you say Y here, additional code will be inserted into the
261 timer routines to collect statistics about kernel timers being
262 reprogrammed. The statistics can be read from /proc/timer_stats.
263 The statistics collection is started by writing 1 to /proc/timer_stats,
264 writing 0 stops it. This feature is useful to collect information
265 about timer usage patterns in kernel and userspace. This feature
266 is lightweight if enabled in the kernel config but not activated
267 (it defaults to deactivated on bootup and will only be activated
268 if some application like powertop activates it explicitly).
270 config DEBUG_OBJECTS
271 bool "Debug object operations"
272 depends on DEBUG_KERNEL
273 help
274 If you say Y here, additional code will be inserted into the
275 kernel to track the life time of various objects and validate
276 the operations on those objects.
278 config DEBUG_OBJECTS_SELFTEST
279 bool "Debug objects selftest"
280 depends on DEBUG_OBJECTS
281 help
282 This enables the selftest of the object debug code.
284 config DEBUG_OBJECTS_FREE
285 bool "Debug objects in freed memory"
286 depends on DEBUG_OBJECTS
287 help
288 This enables checks whether a k/v free operation frees an area
289 which contains an object which has not been deactivated
290 properly. This can make kmalloc/kfree-intensive workloads
291 much slower.
293 config DEBUG_OBJECTS_TIMERS
294 bool "Debug timer objects"
295 depends on DEBUG_OBJECTS
296 help
297 If you say Y here, additional code will be inserted into the
298 timer routines to track the life time of timer objects and
299 validate the timer operations.
301 config DEBUG_OBJECTS_ENABLE_DEFAULT
302 int "debug_objects bootup default value (0-1)"
303 range 0 1
304 default "1"
305 depends on DEBUG_OBJECTS
306 help
307 Debug objects boot parameter default value
309 config DEBUG_SLAB
310 bool "Debug slab memory allocations"
311 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
312 help
313 Say Y here to have the kernel do limited verification on memory
314 allocation as well as poisoning memory on free to catch use of freed
315 memory. This can make kmalloc/kfree-intensive workloads much slower.
317 config DEBUG_SLAB_LEAK
318 bool "Slab memory leak debugging"
319 depends on DEBUG_SLAB
320 default y
321 help
322 Enable /proc/slab_allocators - provides detailed information about
323 which parts of the kernel are using slab objects. May be used for
324 tracking memory leaks and for instrumenting memory usage.
326 config SLUB_DEBUG_ON
327 bool "SLUB debugging on by default"
328 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
329 default n
330 help
331 Boot with debugging on by default. SLUB boots by default with
332 the runtime debug capabilities switched off. Enabling this is
333 equivalent to specifying the "slub_debug" parameter on boot.
334 There is no support for more fine grained debug control like
335 possible with slub_debug=xxx. SLUB debugging may be switched
336 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
337 "slub_debug=-".
339 config SLUB_STATS
340 default n
341 bool "Enable SLUB performance statistics"
342 depends on SLUB && SLUB_DEBUG && SYSFS
343 help
344 SLUB statistics are useful to debug SLUBs allocation behavior in
345 order find ways to optimize the allocator. This should never be
346 enabled for production use since keeping statistics slows down
347 the allocator by a few percentage points. The slabinfo command
348 supports the determination of the most active slabs to figure
349 out which slabs are relevant to a particular load.
350 Try running: slabinfo -DA
352 config SLQB_DEBUG
353 default y
354 bool "Enable SLQB debugging support"
355 depends on SLQB
357 config SLQB_DEBUG_ON
358 default n
359 bool "SLQB debugging on by default"
360 depends on SLQB_DEBUG
362 config SLQB_SYSFS
363 bool "Create SYSFS entries for slab caches"
364 default n
365 depends on SLQB
367 config SLQB_STATS
368 bool "Enable SLQB performance statistics"
369 default n
370 depends on SLQB_SYSFS
372 config DEBUG_KMEMLEAK
373 bool "Kernel memory leak detector"
374 depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
375 (X86 || ARM || PPC || S390)
377 select DEBUG_FS if SYSFS
378 select STACKTRACE if STACKTRACE_SUPPORT
379 select KALLSYMS
380 help
381 Say Y here if you want to enable the memory leak
382 detector. The memory allocation/freeing is traced in a way
383 similar to the Boehm's conservative garbage collector, the
384 difference being that the orphan objects are not freed but
385 only shown in /sys/kernel/debug/kmemleak. Enabling this
386 feature will introduce an overhead to memory
387 allocations. See Documentation/kmemleak.txt for more
388 details.
390 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
391 of finding leaks due to the slab objects poisoning.
393 In order to access the kmemleak file, debugfs needs to be
394 mounted (usually at /sys/kernel/debug).
396 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
397 int "Maximum kmemleak early log entries"
398 depends on DEBUG_KMEMLEAK
399 range 200 40000
400 default 400
401 help
402 Kmemleak must track all the memory allocations to avoid
403 reporting false positives. Since memory may be allocated or
404 freed before kmemleak is initialised, an early log buffer is
405 used to store these actions. If kmemleak reports "early log
406 buffer exceeded", please increase this value.
408 config DEBUG_KMEMLEAK_TEST
409 tristate "Simple test for the kernel memory leak detector"
410 depends on DEBUG_KMEMLEAK
411 help
412 Say Y or M here to build a test for the kernel memory leak
413 detector. This option enables a module that explicitly leaks
414 memory.
416 If unsure, say N.
418 config DEBUG_PREEMPT
419 bool "Debug preemptible kernel"
420 depends on DEBUG_KERNEL && PREEMPT && (TRACE_IRQFLAGS_SUPPORT || PPC64)
421 default y
422 help
423 If you say Y here then the kernel will use a debug variant of the
424 commonly used smp_processor_id() function and will print warnings
425 if kernel code uses it in a preemption-unsafe way. Also, the kernel
426 will detect preemption count underflows.
428 config DEBUG_RT_MUTEXES
429 bool "RT Mutex debugging, deadlock detection"
430 depends on DEBUG_KERNEL && RT_MUTEXES
431 help
432 This allows rt mutex semantics violations and rt mutex related
433 deadlocks (lockups) to be detected and reported automatically.
435 config DEBUG_PI_LIST
436 bool
437 default y
438 depends on DEBUG_RT_MUTEXES
440 config RT_MUTEX_TESTER
441 bool "Built-in scriptable tester for rt-mutexes"
442 depends on DEBUG_KERNEL && RT_MUTEXES
443 help
444 This option enables a rt-mutex tester.
446 config DEBUG_SPINLOCK
447 bool "Spinlock and rw-lock debugging: basic checks"
448 depends on DEBUG_KERNEL
449 help
450 Say Y here and build SMP to catch missing spinlock initialization
451 and certain other kinds of spinlock errors commonly made. This is
452 best used in conjunction with the NMI watchdog so that spinlock
453 deadlocks are also debuggable.
455 config DEBUG_MUTEXES
456 bool "Mutex debugging: basic checks"
457 depends on DEBUG_KERNEL
458 help
459 This feature allows mutex semantics violations to be detected and
460 reported.
462 config DEBUG_LOCK_ALLOC
463 bool "Lock debugging: detect incorrect freeing of live locks"
464 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
465 select DEBUG_SPINLOCK
466 select DEBUG_MUTEXES
467 select LOCKDEP
468 help
469 This feature will check whether any held lock (spinlock, rwlock,
470 mutex or rwsem) is incorrectly freed by the kernel, via any of the
471 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
472 vfree(), etc.), whether a live lock is incorrectly reinitialized via
473 spin_lock_init()/mutex_init()/etc., or whether there is any lock
474 held during task exit.
476 config PROVE_LOCKING
477 bool "Lock debugging: prove locking correctness"
478 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
479 select LOCKDEP
480 select DEBUG_SPINLOCK
481 select DEBUG_MUTEXES
482 select DEBUG_LOCK_ALLOC
483 default n
484 help
485 This feature enables the kernel to prove that all locking
486 that occurs in the kernel runtime is mathematically
487 correct: that under no circumstance could an arbitrary (and
488 not yet triggered) combination of observed locking
489 sequences (on an arbitrary number of CPUs, running an
490 arbitrary number of tasks and interrupt contexts) cause a
491 deadlock.
493 In short, this feature enables the kernel to report locking
494 related deadlocks before they actually occur.
496 The proof does not depend on how hard and complex a
497 deadlock scenario would be to trigger: how many
498 participant CPUs, tasks and irq-contexts would be needed
499 for it to trigger. The proof also does not depend on
500 timing: if a race and a resulting deadlock is possible
501 theoretically (no matter how unlikely the race scenario
502 is), it will be proven so and will immediately be
503 reported by the kernel (once the event is observed that
504 makes the deadlock theoretically possible).
506 If a deadlock is impossible (i.e. the locking rules, as
507 observed by the kernel, are mathematically correct), the
508 kernel reports nothing.
510 NOTE: this feature can also be enabled for rwlocks, mutexes
511 and rwsems - in which case all dependencies between these
512 different locking variants are observed and mapped too, and
513 the proof of observed correctness is also maintained for an
514 arbitrary combination of these separate locking variants.
516 For more details, see Documentation/lockdep-design.txt.
518 config LOCKDEP
519 bool
520 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
521 select STACKTRACE
522 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390
523 select KALLSYMS
524 select KALLSYMS_ALL
526 config LOCK_STAT
527 bool "Lock usage statistics"
528 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
529 select LOCKDEP
530 select DEBUG_SPINLOCK
531 select DEBUG_MUTEXES
532 select DEBUG_LOCK_ALLOC
533 default n
534 help
535 This feature enables tracking lock contention points
537 For more details, see Documentation/lockstat.txt
539 config DEBUG_LOCKDEP
540 bool "Lock dependency engine debugging"
541 depends on DEBUG_KERNEL && LOCKDEP
542 help
543 If you say Y here, the lock dependency engine will do
544 additional runtime checks to debug itself, at the price
545 of more runtime overhead.
547 config TRACE_IRQFLAGS
548 depends on DEBUG_KERNEL
549 bool
550 default y
551 depends on TRACE_IRQFLAGS_SUPPORT
552 depends on PROVE_LOCKING
554 config DEBUG_SPINLOCK_SLEEP
555 bool "Spinlock debugging: sleep-inside-spinlock checking"
556 depends on DEBUG_KERNEL
557 help
558 If you say Y here, various routines which may sleep will become very
559 noisy if they are called with a spinlock held.
561 config DEBUG_LOCKING_API_SELFTESTS
562 bool "Locking API boot-time self-tests"
563 depends on DEBUG_KERNEL
564 help
565 Say Y here if you want the kernel to run a short self-test during
566 bootup. The self-test checks whether common types of locking bugs
567 are detected by debugging mechanisms or not. (if you disable
568 lock debugging then those bugs wont be detected of course.)
569 The following locking APIs are covered: spinlocks, rwlocks,
570 mutexes and rwsems.
572 config STACKTRACE
573 bool
574 depends on STACKTRACE_SUPPORT
576 config DEBUG_KOBJECT
577 bool "kobject debugging"
578 depends on DEBUG_KERNEL
579 help
580 If you say Y here, some extra kobject debugging messages will be sent
581 to the syslog.
583 config DEBUG_HIGHMEM
584 bool "Highmem debugging"
585 depends on DEBUG_KERNEL && HIGHMEM
586 help
587 This options enables addition error checking for high memory systems.
588 Disable for production systems.
590 config DEBUG_BUGVERBOSE
591 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EMBEDDED
592 depends on BUG
593 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
594 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300
595 default !EMBEDDED
596 help
597 Say Y here to make BUG() panics output the file name and line number
598 of the BUG call as well as the EIP and oops trace. This aids
599 debugging but costs about 70-100K of memory.
601 config DEBUG_INFO
602 bool "Compile the kernel with debug info"
603 depends on DEBUG_KERNEL
604 help
605 If you say Y here the resulting kernel image will include
606 debugging info resulting in a larger kernel image.
607 This adds debug symbols to the kernel and modules (gcc -g), and
608 is needed if you intend to use kernel crashdump or binary object
609 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
610 Say Y here only if you plan to debug the kernel.
612 If unsure, say N.
614 config DEBUG_VM
615 bool "Debug VM"
616 depends on DEBUG_KERNEL
617 help
618 Enable this to turn on extended checks in the virtual-memory system
619 that may impact performance.
621 If unsure, say N.
623 config DEBUG_VIRTUAL
624 bool "Debug VM translations"
625 depends on DEBUG_KERNEL && X86
626 help
627 Enable some costly sanity checks in virtual to page code. This can
628 catch mistakes with virt_to_page() and friends.
630 If unsure, say N.
632 config DEBUG_NOMMU_REGIONS
633 bool "Debug the global anon/private NOMMU mapping region tree"
634 depends on DEBUG_KERNEL && !MMU
635 help
636 This option causes the global tree of anonymous and private mapping
637 regions to be regularly checked for invalid topology.
639 config DEBUG_WRITECOUNT
640 bool "Debug filesystem writers count"
641 depends on DEBUG_KERNEL
642 help
643 Enable this to catch wrong use of the writers count in struct
644 vfsmount. This will increase the size of each file struct by
645 32 bits.
647 If unsure, say N.
649 config DEBUG_MEMORY_INIT
650 bool "Debug memory initialisation" if EMBEDDED
651 default !EMBEDDED
652 help
653 Enable this for additional checks during memory initialisation.
654 The sanity checks verify aspects of the VM such as the memory model
655 and other information provided by the architecture. Verbose
656 information will be printed at KERN_DEBUG loglevel depending
657 on the mminit_loglevel= command-line option.
659 If unsure, say Y
661 config DEBUG_LIST
662 bool "Debug linked list manipulation"
663 depends on DEBUG_KERNEL
664 help
665 Enable this to turn on extended checks in the linked-list
666 walking routines.
668 If unsure, say N.
670 config DEBUG_SG
671 bool "Debug SG table operations"
672 depends on DEBUG_KERNEL
673 help
674 Enable this to turn on checks on scatter-gather tables. This can
675 help find problems with drivers that do not properly initialize
676 their sg tables.
678 If unsure, say N.
680 config DEBUG_NOTIFIERS
681 bool "Debug notifier call chains"
682 depends on DEBUG_KERNEL
683 help
684 Enable this to turn on sanity checking for notifier call chains.
685 This is most useful for kernel developers to make sure that
686 modules properly unregister themselves from notifier chains.
687 This is a relatively cheap check but if you care about maximum
688 performance, say N.
690 config DEBUG_CREDENTIALS
691 bool "Debug credential management"
692 depends on DEBUG_KERNEL
693 help
694 Enable this to turn on some debug checking for credential
695 management. The additional code keeps track of the number of
696 pointers from task_structs to any given cred struct, and checks to
697 see that this number never exceeds the usage count of the cred
698 struct.
700 Furthermore, if SELinux is enabled, this also checks that the
701 security pointer in the cred struct is never seen to be invalid.
703 If unsure, say N.
705 #
706 # Select this config option from the architecture Kconfig, if it
707 # it is preferred to always offer frame pointers as a config
708 # option on the architecture (regardless of KERNEL_DEBUG):
709 #
710 config ARCH_WANT_FRAME_POINTERS
711 bool
712 help
714 config FRAME_POINTER
715 bool "Compile the kernel with frame pointers"
716 depends on DEBUG_KERNEL && \
717 (CRIS || M68K || M68KNOMMU || FRV || UML || \
718 AVR32 || SUPERH || BLACKFIN || MN10300) || \
719 ARCH_WANT_FRAME_POINTERS
720 default y
721 help
722 If you say Y here the resulting kernel image will be slightly
723 larger and slower, but it gives very useful debugging information
724 in case of kernel bugs. (precise oopses/stacktraces/warnings)
726 config DEBUG_SYNCHRO_TEST
727 tristate "Synchronisation primitive testing module"
728 depends on DEBUG_KERNEL
729 default n
730 help
731 This option provides a kernel module that can thrash the sleepable
732 synchronisation primitives (mutexes and semaphores).
734 You should say N or M here. Whilst the module can be built in, it's
735 not recommended as it requires module parameters supplying to get it
736 to do anything.
738 See Documentation/synchro-test.txt.
740 config BOOT_PRINTK_DELAY
741 bool "Delay each boot printk message by N milliseconds"
742 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
743 help
744 This build option allows you to read kernel boot messages
745 by inserting a short delay after each one. The delay is
746 specified in milliseconds on the kernel command line,
747 using "boot_delay=N".
749 It is likely that you would also need to use "lpj=M" to preset
750 the "loops per jiffie" value.
751 See a previous boot log for the "lpj" value to use for your
752 system, and then set "lpj=M" before setting "boot_delay=N".
753 NOTE: Using this option may adversely affect SMP systems.
754 I.e., processors other than the first one may not boot up.
755 BOOT_PRINTK_DELAY also may cause DETECT_SOFTLOCKUP to detect
756 what it believes to be lockup conditions.
758 config RCU_TORTURE_TEST
759 tristate "torture tests for RCU"
760 depends on DEBUG_KERNEL
761 default n
762 help
763 This option provides a kernel module that runs torture tests
764 on the RCU infrastructure. The kernel module may be built
765 after the fact on the running kernel to be tested, if desired.
767 Say Y here if you want RCU torture tests to be built into
768 the kernel.
769 Say M if you want the RCU torture tests to build as a module.
770 Say N if you are unsure.
772 config RCU_TORTURE_TEST_RUNNABLE
773 bool "torture tests for RCU runnable by default"
774 depends on RCU_TORTURE_TEST = y
775 default n
776 help
777 This option provides a way to build the RCU torture tests
778 directly into the kernel without them starting up at boot
779 time. You can use /proc/sys/kernel/rcutorture_runnable
780 to manually override this setting. This /proc file is
781 available only when the RCU torture tests have been built
782 into the kernel.
784 Say Y here if you want the RCU torture tests to start during
785 boot (you probably don't).
786 Say N here if you want the RCU torture tests to start only
787 after being manually enabled via /proc.
789 config RCU_CPU_STALL_DETECTOR
790 bool "Check for stalled CPUs delaying RCU grace periods"
791 depends on TREE_RCU || TREE_PREEMPT_RCU
792 default n
793 help
794 This option causes RCU to printk information on which
795 CPUs are delaying the current grace period, but only when
796 the grace period extends for excessive time periods.
798 Say Y if you want RCU to perform such checks.
800 Say N if you are unsure.
802 config KPROBES_SANITY_TEST
803 bool "Kprobes sanity tests"
804 depends on DEBUG_KERNEL
805 depends on KPROBES
806 default n
807 help
808 This option provides for testing basic kprobes functionality on
809 boot. A sample kprobe, jprobe and kretprobe are inserted and
810 verified for functionality.
812 Say N if you are unsure.
814 config BACKTRACE_SELF_TEST
815 tristate "Self test for the backtrace code"
816 depends on DEBUG_KERNEL
817 default n
818 help
819 This option provides a kernel module that can be used to test
820 the kernel stack backtrace code. This option is not useful
821 for distributions or general kernels, but only for kernel
822 developers working on architecture code.
824 Note that if you want to also test saved backtraces, you will
825 have to enable STACKTRACE as well.
827 Say N if you are unsure.
829 config DEBUG_BLOCK_EXT_DEVT
830 bool "Force extended block device numbers and spread them"
831 depends on DEBUG_KERNEL
832 depends on BLOCK
833 default n
834 help
835 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
836 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
837 YOU ARE DOING. Distros, please enable this and fix whatever
838 is broken.
840 Conventionally, block device numbers are allocated from
841 predetermined contiguous area. However, extended block area
842 may introduce non-contiguous block device numbers. This
843 option forces most block device numbers to be allocated from
844 the extended space and spreads them to discover kernel or
845 userland code paths which assume predetermined contiguous
846 device number allocation.
848 Note that turning on this debug option shuffles all the
849 device numbers for all IDE and SCSI devices including libata
850 ones, so root partition specified using device number
851 directly (via rdev or root=MAJ:MIN) won't work anymore.
852 Textual device names (root=/dev/sdXn) will continue to work.
854 Say N if you are unsure.
856 config DEBUG_FORCE_WEAK_PER_CPU
857 bool "Force weak per-cpu definitions"
858 depends on DEBUG_KERNEL
859 help
860 s390 and alpha require percpu variables in modules to be
861 defined weak to work around addressing range issue which
862 puts the following two restrictions on percpu variable
863 definitions.
865 1. percpu symbols must be unique whether static or not
866 2. percpu variables can't be defined inside a function
868 To ensure that generic code follows the above rules, this
869 option forces all percpu variables to be defined as weak.
871 config LKDTM
872 tristate "Linux Kernel Dump Test Tool Module"
873 depends on DEBUG_KERNEL
874 depends on KPROBES
875 depends on BLOCK
876 default n
877 help
878 This module enables testing of the different dumping mechanisms by
879 inducing system failures at predefined crash points.
880 If you don't need it: say N
881 Choose M here to compile this code as a module. The module will be
882 called lkdtm.
884 Documentation on how to use the module can be found in
885 drivers/misc/lkdtm.c
887 config FAULT_INJECTION
888 bool "Fault-injection framework"
889 depends on DEBUG_KERNEL
890 help
891 Provide fault-injection framework.
892 For more details, see Documentation/fault-injection/.
894 config FAILSLAB
895 bool "Fault-injection capability for kmalloc"
896 depends on FAULT_INJECTION
897 depends on SLAB || SLUB
898 help
899 Provide fault-injection capability for kmalloc.
901 config FAIL_PAGE_ALLOC
902 bool "Fault-injection capabilitiy for alloc_pages()"
903 depends on FAULT_INJECTION
904 help
905 Provide fault-injection capability for alloc_pages().
907 config FAIL_MAKE_REQUEST
908 bool "Fault-injection capability for disk IO"
909 depends on FAULT_INJECTION && BLOCK
910 help
911 Provide fault-injection capability for disk IO.
913 config FAIL_IO_TIMEOUT
914 bool "Faul-injection capability for faking disk interrupts"
915 depends on FAULT_INJECTION && BLOCK
916 help
917 Provide fault-injection capability on end IO handling. This
918 will make the block layer "forget" an interrupt as configured,
919 thus exercising the error handling.
921 Only works with drivers that use the generic timeout handling,
922 for others it wont do anything.
924 config FAULT_INJECTION_DEBUG_FS
925 bool "Debugfs entries for fault-injection capabilities"
926 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
927 help
928 Enable configuration of fault-injection capabilities via debugfs.
930 config FAULT_INJECTION_STACKTRACE_FILTER
931 bool "stacktrace filter for fault-injection capabilities"
932 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
933 depends on !X86_64
934 select STACKTRACE
935 select FRAME_POINTER if !PPC && !S390
936 help
937 Provide stacktrace filter for fault-injection capabilities
939 config LATENCYTOP
940 bool "Latency measuring infrastructure"
941 select FRAME_POINTER if !MIPS && !PPC && !S390
942 select KALLSYMS
943 select KALLSYMS_ALL
944 select STACKTRACE
945 select SCHEDSTATS
946 select SCHED_DEBUG
947 depends on HAVE_LATENCYTOP_SUPPORT
948 help
949 Enable this option if you want to use the LatencyTOP tool
950 to find out which userspace is blocking on what kernel operations.
952 config SYSCTL_SYSCALL_CHECK
953 bool "Sysctl checks"
954 depends on SYSCTL_SYSCALL
955 ---help---
956 sys_sysctl uses binary paths that have been found challenging
957 to properly maintain and use. This enables checks that help
958 you to keep things correct.
960 source mm/Kconfig.debug
961 source kernel/trace/Kconfig
963 config PROVIDE_OHCI1394_DMA_INIT
964 bool "Remote debugging over FireWire early on boot"
965 depends on PCI && X86
966 help
967 If you want to debug problems which hang or crash the kernel early
968 on boot and the crashing machine has a FireWire port, you can use
969 this feature to remotely access the memory of the crashed machine
970 over FireWire. This employs remote DMA as part of the OHCI1394
971 specification which is now the standard for FireWire controllers.
973 With remote DMA, you can monitor the printk buffer remotely using
974 firescope and access all memory below 4GB using fireproxy from gdb.
975 Even controlling a kernel debugger is possible using remote DMA.
977 Usage:
979 If ohci1394_dma=early is used as boot parameter, it will initialize
980 all OHCI1394 controllers which are found in the PCI config space.
982 As all changes to the FireWire bus such as enabling and disabling
983 devices cause a bus reset and thereby disable remote DMA for all
984 devices, be sure to have the cable plugged and FireWire enabled on
985 the debugging host before booting the debug target for debugging.
987 This code (~1k) is freed after boot. By then, the firewire stack
988 in charge of the OHCI-1394 controllers should be used instead.
990 See Documentation/debugging-via-ohci1394.txt for more information.
992 config FIREWIRE_OHCI_REMOTE_DMA
993 bool "Remote debugging over FireWire with firewire-ohci"
994 depends on FIREWIRE_OHCI
995 help
996 This option lets you use the FireWire bus for remote debugging
997 with help of the firewire-ohci driver. It enables unfiltered
998 remote DMA in firewire-ohci.
999 See Documentation/debugging-via-ohci1394.txt for more information.
1001 If unsure, say N.
1003 config BUILD_DOCSRC
1004 bool "Build targets in Documentation/ tree"
1005 depends on HEADERS_CHECK
1006 help
1007 This option attempts to build objects from the source files in the
1008 kernel Documentation/ tree.
1010 Say N if you are unsure.
1012 config DYNAMIC_DEBUG
1013 bool "Enable dynamic printk() support"
1014 default n
1015 depends on PRINTK
1016 depends on DEBUG_FS
1017 help
1019 Compiles debug level messages into the kernel, which would not
1020 otherwise be available at runtime. These messages can then be
1021 enabled/disabled based on various levels of scope - per source file,
1022 function, module, format string, and line number. This mechanism
1023 implicitly enables all pr_debug() and dev_dbg() calls. The impact of
1024 this compile option is a larger kernel text size of about 2%.
1026 Usage:
1028 Dynamic debugging is controlled via the 'dynamic_debug/ddebug' file,
1029 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1030 filesystem must first be mounted before making use of this feature.
1031 We refer the control file as: <debugfs>/dynamic_debug/ddebug. This
1032 file contains a list of the debug statements that can be enabled. The
1033 format for each line of the file is:
1035 filename:lineno [module]function flags format
1037 filename : source file of the debug statement
1038 lineno : line number of the debug statement
1039 module : module that contains the debug statement
1040 function : function that contains the debug statement
1041 flags : 'p' means the line is turned 'on' for printing
1042 format : the format used for the debug statement
1044 From a live system:
1046 nullarbor:~ # cat <debugfs>/dynamic_debug/ddebug
1047 # filename:lineno [module]function flags format
1048 fs/aio.c:222 [aio]__put_ioctx - "__put_ioctx:\040freeing\040%p\012"
1049 fs/aio.c:248 [aio]ioctx_alloc - "ENOMEM:\040nr_events\040too\040high\012"
1050 fs/aio.c:1770 [aio]sys_io_cancel - "calling\040cancel\012"
1052 Example usage:
1054 // enable the message at line 1603 of file svcsock.c
1055 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1056 <debugfs>/dynamic_debug/ddebug
1058 // enable all the messages in file svcsock.c
1059 nullarbor:~ # echo -n 'file svcsock.c +p' >
1060 <debugfs>/dynamic_debug/ddebug
1062 // enable all the messages in the NFS server module
1063 nullarbor:~ # echo -n 'module nfsd +p' >
1064 <debugfs>/dynamic_debug/ddebug
1066 // enable all 12 messages in the function svc_process()
1067 nullarbor:~ # echo -n 'func svc_process +p' >
1068 <debugfs>/dynamic_debug/ddebug
1070 // disable all 12 messages in the function svc_process()
1071 nullarbor:~ # echo -n 'func svc_process -p' >
1072 <debugfs>/dynamic_debug/ddebug
1074 See Documentation/dynamic-debug-howto.txt for additional information.
1076 config DMA_API_DEBUG
1077 bool "Enable debugging of DMA-API usage"
1078 depends on HAVE_DMA_API_DEBUG
1079 help
1080 Enable this option to debug the use of the DMA API by device drivers.
1081 With this option you will be able to detect common bugs in device
1082 drivers like double-freeing of DMA mappings or freeing mappings that
1083 were never allocated.
1084 This option causes a performance degredation. Use only if you want
1085 to debug device drivers. If unsure, say N.
1087 source "samples/Kconfig"
1089 source "lib/Kconfig.kgdb"
1091 source "lib/Kconfig.kmemcheck"