| blob | 819ac51202c01006e105f91355d492db6bdd6eb6 |
1 menu "printk and dmesg options"
3 config PRINTK_TIME
4 bool "Show timing information on printks"
5 depends on PRINTK
6 help
7 Selecting this option causes time stamps of the printk()
8 messages to be added to the output of the syslog() system
9 call and at the console.
11 The timestamp is always recorded internally, and exported
12 to /dev/kmsg. This flag just specifies if the timestamp should
13 be included, not that the timestamp is recorded.
15 The behavior is also controlled by the kernel command line
16 parameter printk.time=1. See Documentation/kernel-parameters.txt
18 config DEFAULT_MESSAGE_LOGLEVEL
19 int "Default message log level (1-7)"
20 range 1 7
21 default "4"
22 help
23 Default log level for printk statements with no specified priority.
25 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
26 that are auditing their logs closely may want to set it to a lower
27 priority.
29 config BOOT_PRINTK_DELAY
30 bool "Delay each boot printk message by N milliseconds"
31 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
32 help
33 This build option allows you to read kernel boot messages
34 by inserting a short delay after each one. The delay is
35 specified in milliseconds on the kernel command line,
36 using "boot_delay=N".
38 It is likely that you would also need to use "lpj=M" to preset
39 the "loops per jiffie" value.
40 See a previous boot log for the "lpj" value to use for your
41 system, and then set "lpj=M" before setting "boot_delay=N".
42 NOTE: Using this option may adversely affect SMP systems.
43 I.e., processors other than the first one may not boot up.
44 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
45 what it believes to be lockup conditions.
47 config DYNAMIC_DEBUG
48 bool "Enable dynamic printk() support"
49 default n
50 depends on PRINTK
51 depends on DEBUG_FS
52 help
54 Compiles debug level messages into the kernel, which would not
55 otherwise be available at runtime. These messages can then be
56 enabled/disabled based on various levels of scope - per source file,
57 function, module, format string, and line number. This mechanism
58 implicitly compiles in all pr_debug() and dev_dbg() calls, which
59 enlarges the kernel text size by about 2%.
61 If a source file is compiled with DEBUG flag set, any
62 pr_debug() calls in it are enabled by default, but can be
63 disabled at runtime as below. Note that DEBUG flag is
64 turned on by many CONFIG_*DEBUG* options.
66 Usage:
68 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
69 which is contained in the 'debugfs' filesystem. Thus, the debugfs
70 filesystem must first be mounted before making use of this feature.
71 We refer the control file as: <debugfs>/dynamic_debug/control. This
72 file contains a list of the debug statements that can be enabled. The
73 format for each line of the file is:
75 filename:lineno [module]function flags format
77 filename : source file of the debug statement
78 lineno : line number of the debug statement
79 module : module that contains the debug statement
80 function : function that contains the debug statement
81 flags : '=p' means the line is turned 'on' for printing
82 format : the format used for the debug statement
84 From a live system:
86 nullarbor:~ # cat <debugfs>/dynamic_debug/control
87 # filename:lineno [module]function flags format
88 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
89 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
90 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
92 Example usage:
94 // enable the message at line 1603 of file svcsock.c
95 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
96 <debugfs>/dynamic_debug/control
98 // enable all the messages in file svcsock.c
99 nullarbor:~ # echo -n 'file svcsock.c +p' >
100 <debugfs>/dynamic_debug/control
102 // enable all the messages in the NFS server module
103 nullarbor:~ # echo -n 'module nfsd +p' >
104 <debugfs>/dynamic_debug/control
106 // enable all 12 messages in the function svc_process()
107 nullarbor:~ # echo -n 'func svc_process +p' >
108 <debugfs>/dynamic_debug/control
110 // disable all 12 messages in the function svc_process()
111 nullarbor:~ # echo -n 'func svc_process -p' >
112 <debugfs>/dynamic_debug/control
114 See Documentation/dynamic-debug-howto.txt for additional information.
116 endmenu # "printk and dmesg options"
118 menu "Compile-time checks and compiler options"
120 config DEBUG_INFO
121 bool "Compile the kernel with debug info"
122 depends on DEBUG_KERNEL && !COMPILE_TEST
123 help
124 If you say Y here the resulting kernel image will include
125 debugging info resulting in a larger kernel image.
126 This adds debug symbols to the kernel and modules (gcc -g), and
127 is needed if you intend to use kernel crashdump or binary object
128 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
129 Say Y here only if you plan to debug the kernel.
131 If unsure, say N.
133 config DEBUG_INFO_REDUCED
134 bool "Reduce debugging information"
135 depends on DEBUG_INFO
136 help
137 If you say Y here gcc is instructed to generate less debugging
138 information for structure types. This means that tools that
139 need full debugging information (like kgdb or systemtap) won't
140 be happy. But if you merely need debugging information to
141 resolve line numbers there is no loss. Advantage is that
142 build directory object sizes shrink dramatically over a full
143 DEBUG_INFO build and compile times are reduced too.
144 Only works with newer gcc versions.
146 config ENABLE_WARN_DEPRECATED
147 bool "Enable __deprecated logic"
148 default y
149 help
150 Enable the __deprecated logic in the kernel build.
151 Disable this to suppress the "warning: 'foo' is deprecated
152 (declared at kernel/power/somefile.c:1234)" messages.
154 config ENABLE_MUST_CHECK
155 bool "Enable __must_check logic"
156 default y
157 help
158 Enable the __must_check logic in the kernel build. Disable this to
159 suppress the "warning: ignoring return value of 'foo', declared with
160 attribute warn_unused_result" messages.
162 config FRAME_WARN
163 int "Warn for stack frames larger than (needs gcc 4.4)"
164 range 0 8192
165 default 1024 if !64BIT
166 default 2048 if 64BIT
167 help
168 Tell gcc to warn at build time for stack frames larger than this.
169 Setting this too low will cause a lot of warnings.
170 Setting it to 0 disables the warning.
171 Requires gcc 4.4
173 config STRIP_ASM_SYMS
174 bool "Strip assembler-generated symbols during link"
175 default n
176 help
177 Strip internal assembler-generated symbols during a link (symbols
178 that look like '.Lxxx') so they don't pollute the output of
179 get_wchan() and suchlike.
181 config READABLE_ASM
182 bool "Generate readable assembler code"
183 depends on DEBUG_KERNEL
184 help
185 Disable some compiler optimizations that tend to generate human unreadable
186 assembler output. This may make the kernel slightly slower, but it helps
187 to keep kernel developers who have to stare a lot at assembler listings
188 sane.
190 config UNUSED_SYMBOLS
191 bool "Enable unused/obsolete exported symbols"
192 default y if X86
193 help
194 Unused but exported symbols make the kernel needlessly bigger. For
195 that reason most of these unused exports will soon be removed. This
196 option is provided temporarily to provide a transition period in case
197 some external kernel module needs one of these symbols anyway. If you
198 encounter such a case in your module, consider if you are actually
199 using the right API. (rationale: since nobody in the kernel is using
200 this in a module, there is a pretty good chance it's actually the
201 wrong interface to use). If you really need the symbol, please send a
202 mail to the linux kernel mailing list mentioning the symbol and why
203 you really need it, and what the merge plan to the mainline kernel for
204 your module is.
206 config DEBUG_FS
207 bool "Debug Filesystem"
208 help
209 debugfs is a virtual file system that kernel developers use to put
210 debugging files into. Enable this option to be able to read and
211 write to these files.
213 For detailed documentation on the debugfs API, see
214 Documentation/DocBook/filesystems.
216 If unsure, say N.
218 config HEADERS_CHECK
219 bool "Run 'make headers_check' when building vmlinux"
220 depends on !UML
221 help
222 This option will extract the user-visible kernel headers whenever
223 building the kernel, and will run basic sanity checks on them to
224 ensure that exported files do not attempt to include files which
225 were not exported, etc.
227 If you're making modifications to header files which are
228 relevant for userspace, say 'Y', and check the headers
229 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
230 your build tree), to make sure they're suitable.
232 config DEBUG_SECTION_MISMATCH
233 bool "Enable full Section mismatch analysis"
234 help
235 The section mismatch analysis checks if there are illegal
236 references from one section to another section.
237 During linktime or runtime, some sections are dropped;
238 any use of code/data previously in these sections would
239 most likely result in an oops.
240 In the code, functions and variables are annotated with
241 __init,, etc. (see the full list in include/linux/init.h),
242 which results in the code/data being placed in specific sections.
243 The section mismatch analysis is always performed after a full
244 kernel build, and enabling this option causes the following
245 additional steps to occur:
246 - Add the option -fno-inline-functions-called-once to gcc commands.
247 When inlining a function annotated with __init in a non-init
248 function, we would lose the section information and thus
249 the analysis would not catch the illegal reference.
250 This option tells gcc to inline less (but it does result in
251 a larger kernel).
252 - Run the section mismatch analysis for each module/built-in.o file.
253 When we run the section mismatch analysis on vmlinux.o, we
254 lose valueble information about where the mismatch was
255 introduced.
256 Running the analysis for each module/built-in.o file
257 tells where the mismatch happens much closer to the
258 source. The drawback is that the same mismatch is
259 reported at least twice.
260 - Enable verbose reporting from modpost in order to help resolve
261 the section mismatches that are reported.
263 #
264 # Select this config option from the architecture Kconfig, if it
265 # is preferred to always offer frame pointers as a config
266 # option on the architecture (regardless of KERNEL_DEBUG):
267 #
268 config ARCH_WANT_FRAME_POINTERS
269 bool
270 help
272 config FRAME_POINTER
273 bool "Compile the kernel with frame pointers"
274 depends on DEBUG_KERNEL && \
275 (CRIS || M68K || FRV || UML || \
276 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
277 ARCH_WANT_FRAME_POINTERS
278 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
279 help
280 If you say Y here the resulting kernel image will be slightly
281 larger and slower, but it gives very useful debugging information
282 in case of kernel bugs. (precise oopses/stacktraces/warnings)
284 config DEBUG_FORCE_WEAK_PER_CPU
285 bool "Force weak per-cpu definitions"
286 depends on DEBUG_KERNEL
287 help
288 s390 and alpha require percpu variables in modules to be
289 defined weak to work around addressing range issue which
290 puts the following two restrictions on percpu variable
291 definitions.
293 1. percpu symbols must be unique whether static or not
294 2. percpu variables can't be defined inside a function
296 To ensure that generic code follows the above rules, this
297 option forces all percpu variables to be defined as weak.
299 endmenu # "Compiler options"
301 config MAGIC_SYSRQ
302 bool "Magic SysRq key"
303 depends on !UML
304 help
305 If you say Y here, you will have some control over the system even
306 if the system crashes for example during kernel debugging (e.g., you
307 will be able to flush the buffer cache to disk, reboot the system
308 immediately or dump some status information). This is accomplished
309 by pressing various keys while holding SysRq (Alt+PrintScreen). It
310 also works on a serial console (on PC hardware at least), if you
311 send a BREAK and then within 5 seconds a command keypress. The
312 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
313 unless you really know what this hack does.
315 config MAGIC_SYSRQ_DEFAULT_ENABLE
316 hex "Enable magic SysRq key functions by default"
317 depends on MAGIC_SYSRQ
318 default 0x1
319 help
320 Specifies which SysRq key functions are enabled by default.
321 This may be set to 1 or 0 to enable or disable them all, or
322 to a bitmask as described in Documentation/sysrq.txt.
324 config DEBUG_KERNEL
325 bool "Kernel debugging"
326 help
327 Say Y here if you are developing drivers or trying to debug and
328 identify kernel problems.
330 menu "Memory Debugging"
332 source mm/Kconfig.debug
334 config DEBUG_OBJECTS
335 bool "Debug object operations"
336 depends on DEBUG_KERNEL
337 help
338 If you say Y here, additional code will be inserted into the
339 kernel to track the life time of various objects and validate
340 the operations on those objects.
342 config DEBUG_OBJECTS_SELFTEST
343 bool "Debug objects selftest"
344 depends on DEBUG_OBJECTS
345 help
346 This enables the selftest of the object debug code.
348 config DEBUG_OBJECTS_FREE
349 bool "Debug objects in freed memory"
350 depends on DEBUG_OBJECTS
351 help
352 This enables checks whether a k/v free operation frees an area
353 which contains an object which has not been deactivated
354 properly. This can make kmalloc/kfree-intensive workloads
355 much slower.
357 config DEBUG_OBJECTS_TIMERS
358 bool "Debug timer objects"
359 depends on DEBUG_OBJECTS
360 help
361 If you say Y here, additional code will be inserted into the
362 timer routines to track the life time of timer objects and
363 validate the timer operations.
365 config DEBUG_OBJECTS_WORK
366 bool "Debug work objects"
367 depends on DEBUG_OBJECTS
368 help
369 If you say Y here, additional code will be inserted into the
370 work queue routines to track the life time of work objects and
371 validate the work operations.
373 config DEBUG_OBJECTS_RCU_HEAD
374 bool "Debug RCU callbacks objects"
375 depends on DEBUG_OBJECTS
376 help
377 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
379 config DEBUG_OBJECTS_PERCPU_COUNTER
380 bool "Debug percpu counter objects"
381 depends on DEBUG_OBJECTS
382 help
383 If you say Y here, additional code will be inserted into the
384 percpu counter routines to track the life time of percpu counter
385 objects and validate the percpu counter operations.
387 config DEBUG_OBJECTS_ENABLE_DEFAULT
388 int "debug_objects bootup default value (0-1)"
389 range 0 1
390 default "1"
391 depends on DEBUG_OBJECTS
392 help
393 Debug objects boot parameter default value
395 config DEBUG_SLAB
396 bool "Debug slab memory allocations"
397 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
398 help
399 Say Y here to have the kernel do limited verification on memory
400 allocation as well as poisoning memory on free to catch use of freed
401 memory. This can make kmalloc/kfree-intensive workloads much slower.
403 config DEBUG_SLAB_LEAK
404 bool "Memory leak debugging"
405 depends on DEBUG_SLAB
407 config SLUB_DEBUG_ON
408 bool "SLUB debugging on by default"
409 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
410 default n
411 help
412 Boot with debugging on by default. SLUB boots by default with
413 the runtime debug capabilities switched off. Enabling this is
414 equivalent to specifying the "slub_debug" parameter on boot.
415 There is no support for more fine grained debug control like
416 possible with slub_debug=xxx. SLUB debugging may be switched
417 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
418 "slub_debug=-".
420 config SLUB_STATS
421 default n
422 bool "Enable SLUB performance statistics"
423 depends on SLUB && SYSFS
424 help
425 SLUB statistics are useful to debug SLUBs allocation behavior in
426 order find ways to optimize the allocator. This should never be
427 enabled for production use since keeping statistics slows down
428 the allocator by a few percentage points. The slabinfo command
429 supports the determination of the most active slabs to figure
430 out which slabs are relevant to a particular load.
431 Try running: slabinfo -DA
433 config HAVE_DEBUG_KMEMLEAK
434 bool
436 config DEBUG_KMEMLEAK
437 bool "Kernel memory leak detector"
438 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
439 select DEBUG_FS
440 select STACKTRACE if STACKTRACE_SUPPORT
441 select KALLSYMS
442 select CRC32
443 help
444 Say Y here if you want to enable the memory leak
445 detector. The memory allocation/freeing is traced in a way
446 similar to the Boehm's conservative garbage collector, the
447 difference being that the orphan objects are not freed but
448 only shown in /sys/kernel/debug/kmemleak. Enabling this
449 feature will introduce an overhead to memory
450 allocations. See Documentation/kmemleak.txt for more
451 details.
453 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
454 of finding leaks due to the slab objects poisoning.
456 In order to access the kmemleak file, debugfs needs to be
457 mounted (usually at /sys/kernel/debug).
459 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
460 int "Maximum kmemleak early log entries"
461 depends on DEBUG_KMEMLEAK
462 range 200 40000
463 default 400
464 help
465 Kmemleak must track all the memory allocations to avoid
466 reporting false positives. Since memory may be allocated or
467 freed before kmemleak is initialised, an early log buffer is
468 used to store these actions. If kmemleak reports "early log
469 buffer exceeded", please increase this value.
471 config DEBUG_KMEMLEAK_TEST
472 tristate "Simple test for the kernel memory leak detector"
473 depends on DEBUG_KMEMLEAK && m
474 help
475 This option enables a module that explicitly leaks memory.
477 If unsure, say N.
479 config DEBUG_KMEMLEAK_DEFAULT_OFF
480 bool "Default kmemleak to off"
481 depends on DEBUG_KMEMLEAK
482 help
483 Say Y here to disable kmemleak by default. It can then be enabled
484 on the command line via kmemleak=on.
486 config DEBUG_STACK_USAGE
487 bool "Stack utilization instrumentation"
488 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
489 help
490 Enables the display of the minimum amount of free stack which each
491 task has ever had available in the sysrq-T and sysrq-P debug output.
493 This option will slow down process creation somewhat.
495 config DEBUG_VM
496 bool "Debug VM"
497 depends on DEBUG_KERNEL
498 help
499 Enable this to turn on extended checks in the virtual-memory system
500 that may impact performance.
502 If unsure, say N.
504 config DEBUG_VM_RB
505 bool "Debug VM red-black trees"
506 depends on DEBUG_VM
507 help
508 Enable VM red-black tree debugging information and extra validations.
510 If unsure, say N.
512 config DEBUG_VIRTUAL
513 bool "Debug VM translations"
514 depends on DEBUG_KERNEL && X86
515 help
516 Enable some costly sanity checks in virtual to page code. This can
517 catch mistakes with virt_to_page() and friends.
519 If unsure, say N.
521 config DEBUG_NOMMU_REGIONS
522 bool "Debug the global anon/private NOMMU mapping region tree"
523 depends on DEBUG_KERNEL && !MMU
524 help
525 This option causes the global tree of anonymous and private mapping
526 regions to be regularly checked for invalid topology.
528 config DEBUG_MEMORY_INIT
529 bool "Debug memory initialisation" if EXPERT
530 default !EXPERT
531 help
532 Enable this for additional checks during memory initialisation.
533 The sanity checks verify aspects of the VM such as the memory model
534 and other information provided by the architecture. Verbose
535 information will be printed at KERN_DEBUG loglevel depending
536 on the mminit_loglevel= command-line option.
538 If unsure, say Y
540 config MEMORY_NOTIFIER_ERROR_INJECT
541 tristate "Memory hotplug notifier error injection module"
542 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
543 help
544 This option provides the ability to inject artificial errors to
545 memory hotplug notifier chain callbacks. It is controlled through
546 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
548 If the notifier call chain should be failed with some events
549 notified, write the error code to "actions/<notifier event>/error".
551 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
553 # cd /sys/kernel/debug/notifier-error-inject/memory
554 # echo -12 > actions/MEM_GOING_OFFLINE/error
555 # echo offline > /sys/devices/system/memory/memoryXXX/state
556 bash: echo: write error: Cannot allocate memory
558 To compile this code as a module, choose M here: the module will
559 be called memory-notifier-error-inject.
561 If unsure, say N.
563 config DEBUG_PER_CPU_MAPS
564 bool "Debug access to per_cpu maps"
565 depends on DEBUG_KERNEL
566 depends on SMP
567 help
568 Say Y to verify that the per_cpu map being accessed has
569 been set up. This adds a fair amount of code to kernel memory
570 and decreases performance.
572 Say N if unsure.
574 config DEBUG_HIGHMEM
575 bool "Highmem debugging"
576 depends on DEBUG_KERNEL && HIGHMEM
577 help
578 This options enables addition error checking for high memory systems.
579 Disable for production systems.
581 config HAVE_DEBUG_STACKOVERFLOW
582 bool
584 config DEBUG_STACKOVERFLOW
585 bool "Check for stack overflows"
586 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
587 ---help---
588 Say Y here if you want to check for overflows of kernel, IRQ
589 and exception stacks (if your archicture uses them). This
590 option will show detailed messages if free stack space drops
591 below a certain limit.
593 These kinds of bugs usually occur when call-chains in the
594 kernel get too deep, especially when interrupts are
595 involved.
597 Use this in cases where you see apparently random memory
598 corruption, especially if it appears in 'struct thread_info'
600 If in doubt, say "N".
602 source "lib/Kconfig.kmemcheck"
604 endmenu # "Memory Debugging"
606 config DEBUG_SHIRQ
607 bool "Debug shared IRQ handlers"
608 depends on DEBUG_KERNEL
609 help
610 Enable this to generate a spurious interrupt as soon as a shared
611 interrupt handler is registered, and just before one is deregistered.
612 Drivers ought to be able to handle interrupts coming in at those
613 points; some don't and need to be caught.
615 menu "Debug Lockups and Hangs"
617 config LOCKUP_DETECTOR
618 bool "Detect Hard and Soft Lockups"
619 depends on DEBUG_KERNEL && !S390
620 help
621 Say Y here to enable the kernel to act as a watchdog to detect
622 hard and soft lockups.
624 Softlockups are bugs that cause the kernel to loop in kernel
625 mode for more than 20 seconds, without giving other tasks a
626 chance to run. The current stack trace is displayed upon
627 detection and the system will stay locked up.
629 Hardlockups are bugs that cause the CPU to loop in kernel mode
630 for more than 10 seconds, without letting other interrupts have a
631 chance to run. The current stack trace is displayed upon detection
632 and the system will stay locked up.
634 The overhead should be minimal. A periodic hrtimer runs to
635 generate interrupts and kick the watchdog task every 4 seconds.
636 An NMI is generated every 10 seconds or so to check for hardlockups.
638 The frequency of hrtimer and NMI events and the soft and hard lockup
639 thresholds can be controlled through the sysctl watchdog_thresh.
641 config HARDLOCKUP_DETECTOR
642 def_bool y
643 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
644 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
646 config BOOTPARAM_HARDLOCKUP_PANIC
647 bool "Panic (Reboot) On Hard Lockups"
648 depends on HARDLOCKUP_DETECTOR
649 help
650 Say Y here to enable the kernel to panic on "hard lockups",
651 which are bugs that cause the kernel to loop in kernel
652 mode with interrupts disabled for more than 10 seconds (configurable
653 using the watchdog_thresh sysctl).
655 Say N if unsure.
657 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
658 int
659 depends on HARDLOCKUP_DETECTOR
660 range 0 1
661 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
662 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
664 config BOOTPARAM_SOFTLOCKUP_PANIC
665 bool "Panic (Reboot) On Soft Lockups"
666 depends on LOCKUP_DETECTOR
667 help
668 Say Y here to enable the kernel to panic on "soft lockups",
669 which are bugs that cause the kernel to loop in kernel
670 mode for more than 20 seconds (configurable using the watchdog_thresh
671 sysctl), without giving other tasks a chance to run.
673 The panic can be used in combination with panic_timeout,
674 to cause the system to reboot automatically after a
675 lockup has been detected. This feature is useful for
676 high-availability systems that have uptime guarantees and
677 where a lockup must be resolved ASAP.
679 Say N if unsure.
681 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
682 int
683 depends on LOCKUP_DETECTOR
684 range 0 1
685 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
686 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
688 config DETECT_HUNG_TASK
689 bool "Detect Hung Tasks"
690 depends on DEBUG_KERNEL
691 default LOCKUP_DETECTOR
692 help
693 Say Y here to enable the kernel to detect "hung tasks",
694 which are bugs that cause the task to be stuck in
695 uninterruptible "D" state indefinitiley.
697 When a hung task is detected, the kernel will print the
698 current stack trace (which you should report), but the
699 task will stay in uninterruptible state. If lockdep is
700 enabled then all held locks will also be reported. This
701 feature has negligible overhead.
703 config DEFAULT_HUNG_TASK_TIMEOUT
704 int "Default timeout for hung task detection (in seconds)"
705 depends on DETECT_HUNG_TASK
706 default 120
707 help
708 This option controls the default timeout (in seconds) used
709 to determine when a task has become non-responsive and should
710 be considered hung.
712 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
713 sysctl or by writing a value to
714 /proc/sys/kernel/hung_task_timeout_secs.
716 A timeout of 0 disables the check. The default is two minutes.
717 Keeping the default should be fine in most cases.
719 config BOOTPARAM_HUNG_TASK_PANIC
720 bool "Panic (Reboot) On Hung Tasks"
721 depends on DETECT_HUNG_TASK
722 help
723 Say Y here to enable the kernel to panic on "hung tasks",
724 which are bugs that cause the kernel to leave a task stuck
725 in uninterruptible "D" state.
727 The panic can be used in combination with panic_timeout,
728 to cause the system to reboot automatically after a
729 hung task has been detected. This feature is useful for
730 high-availability systems that have uptime guarantees and
731 where a hung tasks must be resolved ASAP.
733 Say N if unsure.
735 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
736 int
737 depends on DETECT_HUNG_TASK
738 range 0 1
739 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
740 default 1 if BOOTPARAM_HUNG_TASK_PANIC
742 endmenu # "Debug lockups and hangs"
744 config PANIC_ON_OOPS
745 bool "Panic on Oops"
746 help
747 Say Y here to enable the kernel to panic when it oopses. This
748 has the same effect as setting oops=panic on the kernel command
749 line.
751 This feature is useful to ensure that the kernel does not do
752 anything erroneous after an oops which could result in data
753 corruption or other issues.
755 Say N if unsure.
757 config PANIC_ON_OOPS_VALUE
758 int
759 range 0 1
760 default 0 if !PANIC_ON_OOPS
761 default 1 if PANIC_ON_OOPS
763 config PANIC_TIMEOUT
764 int "panic timeout"
765 default 0
766 help
767 Set the timeout value (in seconds) until a reboot occurs when the
768 the kernel panics. If n = 0, then we wait forever. A timeout
769 value n > 0 will wait n seconds before rebooting, while a timeout
770 value n < 0 will reboot immediately.
772 config SCHED_DEBUG
773 bool "Collect scheduler debugging info"
774 depends on DEBUG_KERNEL && PROC_FS
775 default y
776 help
777 If you say Y here, the /proc/sched_debug file will be provided
778 that can help debug the scheduler. The runtime overhead of this
779 option is minimal.
781 config SCHEDSTATS
782 bool "Collect scheduler statistics"
783 depends on DEBUG_KERNEL && PROC_FS
784 help
785 If you say Y here, additional code will be inserted into the
786 scheduler and related routines to collect statistics about
787 scheduler behavior and provide them in /proc/schedstat. These
788 stats may be useful for both tuning and debugging the scheduler
789 If you aren't debugging the scheduler or trying to tune a specific
790 application, you can say N to avoid the very slight overhead
791 this adds.
793 config TIMER_STATS
794 bool "Collect kernel timers statistics"
795 depends on DEBUG_KERNEL && PROC_FS
796 help
797 If you say Y here, additional code will be inserted into the
798 timer routines to collect statistics about kernel timers being
799 reprogrammed. The statistics can be read from /proc/timer_stats.
800 The statistics collection is started by writing 1 to /proc/timer_stats,
801 writing 0 stops it. This feature is useful to collect information
802 about timer usage patterns in kernel and userspace. This feature
803 is lightweight if enabled in the kernel config but not activated
804 (it defaults to deactivated on bootup and will only be activated
805 if some application like powertop activates it explicitly).
807 config DEBUG_PREEMPT
808 bool "Debug preemptible kernel"
809 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
810 default y
811 help
812 If you say Y here then the kernel will use a debug variant of the
813 commonly used smp_processor_id() function and will print warnings
814 if kernel code uses it in a preemption-unsafe way. Also, the kernel
815 will detect preemption count underflows.
817 menu "Lock Debugging (spinlocks, mutexes, etc...)"
819 config DEBUG_RT_MUTEXES
820 bool "RT Mutex debugging, deadlock detection"
821 depends on DEBUG_KERNEL && RT_MUTEXES
822 help
823 This allows rt mutex semantics violations and rt mutex related
824 deadlocks (lockups) to be detected and reported automatically.
826 config DEBUG_PI_LIST
827 bool
828 default y
829 depends on DEBUG_RT_MUTEXES
831 config RT_MUTEX_TESTER
832 bool "Built-in scriptable tester for rt-mutexes"
833 depends on DEBUG_KERNEL && RT_MUTEXES
834 help
835 This option enables a rt-mutex tester.
837 config DEBUG_SPINLOCK
838 bool "Spinlock and rw-lock debugging: basic checks"
839 depends on DEBUG_KERNEL
840 select UNINLINE_SPIN_UNLOCK
841 help
842 Say Y here and build SMP to catch missing spinlock initialization
843 and certain other kinds of spinlock errors commonly made. This is
844 best used in conjunction with the NMI watchdog so that spinlock
845 deadlocks are also debuggable.
847 config DEBUG_MUTEXES
848 bool "Mutex debugging: basic checks"
849 depends on DEBUG_KERNEL
850 help
851 This feature allows mutex semantics violations to be detected and
852 reported.
854 config DEBUG_WW_MUTEX_SLOWPATH
855 bool "Wait/wound mutex debugging: Slowpath testing"
856 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
857 select DEBUG_LOCK_ALLOC
858 select DEBUG_SPINLOCK
859 select DEBUG_MUTEXES
860 help
861 This feature enables slowpath testing for w/w mutex users by
862 injecting additional -EDEADLK wound/backoff cases. Together with
863 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
864 will test all possible w/w mutex interface abuse with the
865 exception of simply not acquiring all the required locks.
867 config DEBUG_LOCK_ALLOC
868 bool "Lock debugging: detect incorrect freeing of live locks"
869 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
870 select DEBUG_SPINLOCK
871 select DEBUG_MUTEXES
872 select LOCKDEP
873 help
874 This feature will check whether any held lock (spinlock, rwlock,
875 mutex or rwsem) is incorrectly freed by the kernel, via any of the
876 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
877 vfree(), etc.), whether a live lock is incorrectly reinitialized via
878 spin_lock_init()/mutex_init()/etc., or whether there is any lock
879 held during task exit.
881 config PROVE_LOCKING
882 bool "Lock debugging: prove locking correctness"
883 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
884 select LOCKDEP
885 select DEBUG_SPINLOCK
886 select DEBUG_MUTEXES
887 select DEBUG_LOCK_ALLOC
888 select TRACE_IRQFLAGS
889 default n
890 help
891 This feature enables the kernel to prove that all locking
892 that occurs in the kernel runtime is mathematically
893 correct: that under no circumstance could an arbitrary (and
894 not yet triggered) combination of observed locking
895 sequences (on an arbitrary number of CPUs, running an
896 arbitrary number of tasks and interrupt contexts) cause a
897 deadlock.
899 In short, this feature enables the kernel to report locking
900 related deadlocks before they actually occur.
902 The proof does not depend on how hard and complex a
903 deadlock scenario would be to trigger: how many
904 participant CPUs, tasks and irq-contexts would be needed
905 for it to trigger. The proof also does not depend on
906 timing: if a race and a resulting deadlock is possible
907 theoretically (no matter how unlikely the race scenario
908 is), it will be proven so and will immediately be
909 reported by the kernel (once the event is observed that
910 makes the deadlock theoretically possible).
912 If a deadlock is impossible (i.e. the locking rules, as
913 observed by the kernel, are mathematically correct), the
914 kernel reports nothing.
916 NOTE: this feature can also be enabled for rwlocks, mutexes
917 and rwsems - in which case all dependencies between these
918 different locking variants are observed and mapped too, and
919 the proof of observed correctness is also maintained for an
920 arbitrary combination of these separate locking variants.
922 For more details, see Documentation/lockdep-design.txt.
924 config LOCKDEP
925 bool
926 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
927 select STACKTRACE
928 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC
929 select KALLSYMS
930 select KALLSYMS_ALL
932 config LOCK_STAT
933 bool "Lock usage statistics"
934 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
935 select LOCKDEP
936 select DEBUG_SPINLOCK
937 select DEBUG_MUTEXES
938 select DEBUG_LOCK_ALLOC
939 default n
940 help
941 This feature enables tracking lock contention points
943 For more details, see Documentation/lockstat.txt
945 This also enables lock events required by "perf lock",
946 subcommand of perf.
947 If you want to use "perf lock", you also need to turn on
948 CONFIG_EVENT_TRACING.
950 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
951 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
953 config DEBUG_LOCKDEP
954 bool "Lock dependency engine debugging"
955 depends on DEBUG_KERNEL && LOCKDEP
956 help
957 If you say Y here, the lock dependency engine will do
958 additional runtime checks to debug itself, at the price
959 of more runtime overhead.
961 config DEBUG_ATOMIC_SLEEP
962 bool "Sleep inside atomic section checking"
963 select PREEMPT_COUNT
964 depends on DEBUG_KERNEL
965 help
966 If you say Y here, various routines which may sleep will become very
967 noisy if they are called inside atomic sections: when a spinlock is
968 held, inside an rcu read side critical section, inside preempt disabled
969 sections, inside an interrupt, etc...
971 config DEBUG_LOCKING_API_SELFTESTS
972 bool "Locking API boot-time self-tests"
973 depends on DEBUG_KERNEL
974 help
975 Say Y here if you want the kernel to run a short self-test during
976 bootup. The self-test checks whether common types of locking bugs
977 are detected by debugging mechanisms or not. (if you disable
978 lock debugging then those bugs wont be detected of course.)
979 The following locking APIs are covered: spinlocks, rwlocks,
980 mutexes and rwsems.
982 config LOCK_TORTURE_TEST
983 tristate "torture tests for locking"
984 depends on DEBUG_KERNEL
985 select TORTURE_TEST
986 default n
987 help
988 This option provides a kernel module that runs torture tests
989 on kernel locking primitives. The kernel module may be built
990 after the fact on the running kernel to be tested, if desired.
992 Say Y here if you want kernel locking-primitive torture tests
993 to be built into the kernel.
994 Say M if you want these torture tests to build as a module.
995 Say N if you are unsure.
997 endmenu # lock debugging
999 config TRACE_IRQFLAGS
1000 bool
1001 help
1002 Enables hooks to interrupt enabling and disabling for
1003 either tracing or lock debugging.
1005 config STACKTRACE
1006 bool
1007 depends on STACKTRACE_SUPPORT
1009 config DEBUG_KOBJECT
1010 bool "kobject debugging"
1011 depends on DEBUG_KERNEL
1012 help
1013 If you say Y here, some extra kobject debugging messages will be sent
1014 to the syslog.
1016 config DEBUG_KOBJECT_RELEASE
1017 bool "kobject release debugging"
1018 depends on DEBUG_OBJECTS_TIMERS
1019 help
1020 kobjects are reference counted objects. This means that their
1021 last reference count put is not predictable, and the kobject can
1022 live on past the point at which a driver decides to drop it's
1023 initial reference to the kobject gained on allocation. An
1024 example of this would be a struct device which has just been
1025 unregistered.
1027 However, some buggy drivers assume that after such an operation,
1028 the memory backing the kobject can be immediately freed. This
1029 goes completely against the principles of a refcounted object.
1031 If you say Y here, the kernel will delay the release of kobjects
1032 on the last reference count to improve the visibility of this
1033 kind of kobject release bug.
1035 config HAVE_DEBUG_BUGVERBOSE
1036 bool
1038 config DEBUG_BUGVERBOSE
1039 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1040 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1041 default y
1042 help
1043 Say Y here to make BUG() panics output the file name and line number
1044 of the BUG call as well as the EIP and oops trace. This aids
1045 debugging but costs about 70-100K of memory.
1047 config DEBUG_LIST
1048 bool "Debug linked list manipulation"
1049 depends on DEBUG_KERNEL
1050 help
1051 Enable this to turn on extended checks in the linked-list
1052 walking routines.
1054 If unsure, say N.
1056 config DEBUG_SG
1057 bool "Debug SG table operations"
1058 depends on DEBUG_KERNEL
1059 help
1060 Enable this to turn on checks on scatter-gather tables. This can
1061 help find problems with drivers that do not properly initialize
1062 their sg tables.
1064 If unsure, say N.
1066 config DEBUG_NOTIFIERS
1067 bool "Debug notifier call chains"
1068 depends on DEBUG_KERNEL
1069 help
1070 Enable this to turn on sanity checking for notifier call chains.
1071 This is most useful for kernel developers to make sure that
1072 modules properly unregister themselves from notifier chains.
1073 This is a relatively cheap check but if you care about maximum
1074 performance, say N.
1076 config DEBUG_CREDENTIALS
1077 bool "Debug credential management"
1078 depends on DEBUG_KERNEL
1079 help
1080 Enable this to turn on some debug checking for credential
1081 management. The additional code keeps track of the number of
1082 pointers from task_structs to any given cred struct, and checks to
1083 see that this number never exceeds the usage count of the cred
1084 struct.
1086 Furthermore, if SELinux is enabled, this also checks that the
1087 security pointer in the cred struct is never seen to be invalid.
1089 If unsure, say N.
1091 menu "RCU Debugging"
1093 config PROVE_RCU
1094 bool "RCU debugging: prove RCU correctness"
1095 depends on PROVE_LOCKING
1096 default n
1097 help
1098 This feature enables lockdep extensions that check for correct
1099 use of RCU APIs. This is currently under development. Say Y
1100 if you want to debug RCU usage or help work on the PROVE_RCU
1101 feature.
1103 Say N if you are unsure.
1105 config PROVE_RCU_REPEATEDLY
1106 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1107 depends on PROVE_RCU
1108 default n
1109 help
1110 By itself, PROVE_RCU will disable checking upon issuing the
1111 first warning (or "splat"). This feature prevents such
1112 disabling, allowing multiple RCU-lockdep warnings to be printed
1113 on a single reboot.
1115 Say Y to allow multiple RCU-lockdep warnings per boot.
1117 Say N if you are unsure.
1119 config PROVE_RCU_DELAY
1120 bool "RCU debugging: preemptible RCU race provocation"
1121 depends on DEBUG_KERNEL && PREEMPT_RCU
1122 default n
1123 help
1124 There is a class of races that involve an unlikely preemption
1125 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
1126 been set to INT_MIN. This feature inserts a delay at that
1127 point to increase the probability of these races.
1129 Say Y to increase probability of preemption of __rcu_read_unlock().
1131 Say N if you are unsure.
1133 config SPARSE_RCU_POINTER
1134 bool "RCU debugging: sparse-based checks for pointer usage"
1135 default n
1136 help
1137 This feature enables the __rcu sparse annotation for
1138 RCU-protected pointers. This annotation will cause sparse
1139 to flag any non-RCU used of annotated pointers. This can be
1140 helpful when debugging RCU usage. Please note that this feature
1141 is not intended to enforce code cleanliness; it is instead merely
1142 a debugging aid.
1144 Say Y to make sparse flag questionable use of RCU-protected pointers
1146 Say N if you are unsure.
1148 config TORTURE_TEST
1149 tristate
1150 default n
1152 config RCU_TORTURE_TEST
1153 tristate "torture tests for RCU"
1154 depends on DEBUG_KERNEL
1155 select TORTURE_TEST
1156 default n
1157 help
1158 This option provides a kernel module that runs torture tests
1159 on the RCU infrastructure. The kernel module may be built
1160 after the fact on the running kernel to be tested, if desired.
1162 Say Y here if you want RCU torture tests to be built into
1163 the kernel.
1164 Say M if you want the RCU torture tests to build as a module.
1165 Say N if you are unsure.
1167 config RCU_TORTURE_TEST_RUNNABLE
1168 bool "torture tests for RCU runnable by default"
1169 depends on RCU_TORTURE_TEST = y
1170 default n
1171 help
1172 This option provides a way to build the RCU torture tests
1173 directly into the kernel without them starting up at boot
1174 time. You can use /proc/sys/kernel/rcutorture_runnable
1175 to manually override this setting. This /proc file is
1176 available only when the RCU torture tests have been built
1177 into the kernel.
1179 Say Y here if you want the RCU torture tests to start during
1180 boot (you probably don't).
1181 Say N here if you want the RCU torture tests to start only
1182 after being manually enabled via /proc.
1184 config RCU_CPU_STALL_TIMEOUT
1185 int "RCU CPU stall timeout in seconds"
1186 depends on RCU_STALL_COMMON
1187 range 3 300
1188 default 21
1189 help
1190 If a given RCU grace period extends more than the specified
1191 number of seconds, a CPU stall warning is printed. If the
1192 RCU grace period persists, additional CPU stall warnings are
1193 printed at more widely spaced intervals.
1195 config RCU_CPU_STALL_VERBOSE
1196 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
1197 depends on TREE_PREEMPT_RCU
1198 default y
1199 help
1200 This option causes RCU to printk detailed per-task information
1201 for any tasks that are stalling the current RCU grace period.
1203 Say N if you are unsure.
1205 Say Y if you want to enable such checks.
1207 config RCU_CPU_STALL_INFO
1208 bool "Print additional diagnostics on RCU CPU stall"
1209 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1210 default n
1211 help
1212 For each stalled CPU that is aware of the current RCU grace
1213 period, print out additional per-CPU diagnostic information
1214 regarding scheduling-clock ticks, idle state, and,
1215 for RCU_FAST_NO_HZ kernels, idle-entry state.
1217 Say N if you are unsure.
1219 Say Y if you want to enable such diagnostics.
1221 config RCU_TRACE
1222 bool "Enable tracing for RCU"
1223 depends on DEBUG_KERNEL
1224 select TRACE_CLOCK
1225 help
1226 This option provides tracing in RCU which presents stats
1227 in debugfs for debugging RCU implementation.
1229 Say Y here if you want to enable RCU tracing
1230 Say N if you are unsure.
1232 endmenu # "RCU Debugging"
1234 config DEBUG_BLOCK_EXT_DEVT
1235 bool "Force extended block device numbers and spread them"
1236 depends on DEBUG_KERNEL
1237 depends on BLOCK
1238 default n
1239 help
1240 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1241 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1242 YOU ARE DOING. Distros, please enable this and fix whatever
1243 is broken.
1245 Conventionally, block device numbers are allocated from
1246 predetermined contiguous area. However, extended block area
1247 may introduce non-contiguous block device numbers. This
1248 option forces most block device numbers to be allocated from
1249 the extended space and spreads them to discover kernel or
1250 userland code paths which assume predetermined contiguous
1251 device number allocation.
1253 Note that turning on this debug option shuffles all the
1254 device numbers for all IDE and SCSI devices including libata
1255 ones, so root partition specified using device number
1256 directly (via rdev or root=MAJ:MIN) won't work anymore.
1257 Textual device names (root=/dev/sdXn) will continue to work.
1259 Say N if you are unsure.
1261 config NOTIFIER_ERROR_INJECTION
1262 tristate "Notifier error injection"
1263 depends on DEBUG_KERNEL
1264 select DEBUG_FS
1265 help
1266 This option provides the ability to inject artificial errors to
1267 specified notifier chain callbacks. It is useful to test the error
1268 handling of notifier call chain failures.
1270 Say N if unsure.
1272 config CPU_NOTIFIER_ERROR_INJECT
1273 tristate "CPU notifier error injection module"
1274 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1275 help
1276 This option provides a kernel module that can be used to test
1277 the error handling of the cpu notifiers by injecting artificial
1278 errors to CPU notifier chain callbacks. It is controlled through
1279 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1281 If the notifier call chain should be failed with some events
1282 notified, write the error code to "actions/<notifier event>/error".
1284 Example: Inject CPU offline error (-1 == -EPERM)
1286 # cd /sys/kernel/debug/notifier-error-inject/cpu
1287 # echo -1 > actions/CPU_DOWN_PREPARE/error
1288 # echo 0 > /sys/devices/system/cpu/cpu1/online
1289 bash: echo: write error: Operation not permitted
1291 To compile this code as a module, choose M here: the module will
1292 be called cpu-notifier-error-inject.
1294 If unsure, say N.
1296 config PM_NOTIFIER_ERROR_INJECT
1297 tristate "PM notifier error injection module"
1298 depends on PM && NOTIFIER_ERROR_INJECTION
1299 default m if PM_DEBUG
1300 help
1301 This option provides the ability to inject artificial errors to
1302 PM notifier chain callbacks. It is controlled through debugfs
1303 interface /sys/kernel/debug/notifier-error-inject/pm
1305 If the notifier call chain should be failed with some events
1306 notified, write the error code to "actions/<notifier event>/error".
1308 Example: Inject PM suspend error (-12 = -ENOMEM)
1310 # cd /sys/kernel/debug/notifier-error-inject/pm/
1311 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1312 # echo mem > /sys/power/state
1313 bash: echo: write error: Cannot allocate memory
1315 To compile this code as a module, choose M here: the module will
1316 be called pm-notifier-error-inject.
1318 If unsure, say N.
1320 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1321 tristate "OF reconfig notifier error injection module"
1322 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1323 help
1324 This option provides the ability to inject artificial errors to
1325 OF reconfig notifier chain callbacks. It is controlled
1326 through debugfs interface under
1327 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1329 If the notifier call chain should be failed with some events
1330 notified, write the error code to "actions/<notifier event>/error".
1332 To compile this code as a module, choose M here: the module will
1333 be called of-reconfig-notifier-error-inject.
1335 If unsure, say N.
1337 config FAULT_INJECTION
1338 bool "Fault-injection framework"
1339 depends on DEBUG_KERNEL
1340 help
1341 Provide fault-injection framework.
1342 For more details, see Documentation/fault-injection/.
1344 config FAILSLAB
1345 bool "Fault-injection capability for kmalloc"
1346 depends on FAULT_INJECTION
1347 depends on SLAB || SLUB
1348 help
1349 Provide fault-injection capability for kmalloc.
1351 config FAIL_PAGE_ALLOC
1352 bool "Fault-injection capabilitiy for alloc_pages()"
1353 depends on FAULT_INJECTION
1354 help
1355 Provide fault-injection capability for alloc_pages().
1357 config FAIL_MAKE_REQUEST
1358 bool "Fault-injection capability for disk IO"
1359 depends on FAULT_INJECTION && BLOCK
1360 help
1361 Provide fault-injection capability for disk IO.
1363 config FAIL_IO_TIMEOUT
1364 bool "Fault-injection capability for faking disk interrupts"
1365 depends on FAULT_INJECTION && BLOCK
1366 help
1367 Provide fault-injection capability on end IO handling. This
1368 will make the block layer "forget" an interrupt as configured,
1369 thus exercising the error handling.
1371 Only works with drivers that use the generic timeout handling,
1372 for others it wont do anything.
1374 config FAIL_MMC_REQUEST
1375 bool "Fault-injection capability for MMC IO"
1376 select DEBUG_FS
1377 depends on FAULT_INJECTION && MMC
1378 help
1379 Provide fault-injection capability for MMC IO.
1380 This will make the mmc core return data errors. This is
1381 useful to test the error handling in the mmc block device
1382 and to test how the mmc host driver handles retries from
1383 the block device.
1385 config FAULT_INJECTION_DEBUG_FS
1386 bool "Debugfs entries for fault-injection capabilities"
1387 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1388 help
1389 Enable configuration of fault-injection capabilities via debugfs.
1391 config FAULT_INJECTION_STACKTRACE_FILTER
1392 bool "stacktrace filter for fault-injection capabilities"
1393 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1394 depends on !X86_64
1395 select STACKTRACE
1396 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1397 help
1398 Provide stacktrace filter for fault-injection capabilities
1400 config LATENCYTOP
1401 bool "Latency measuring infrastructure"
1402 depends on HAVE_LATENCYTOP_SUPPORT
1403 depends on DEBUG_KERNEL
1404 depends on STACKTRACE_SUPPORT
1405 depends on PROC_FS
1406 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1407 select KALLSYMS
1408 select KALLSYMS_ALL
1409 select STACKTRACE
1410 select SCHEDSTATS
1411 select SCHED_DEBUG
1412 help
1413 Enable this option if you want to use the LatencyTOP tool
1414 to find out which userspace is blocking on what kernel operations.
1416 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1417 bool
1419 config DEBUG_STRICT_USER_COPY_CHECKS
1420 bool "Strict user copy size checks"
1421 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1422 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1423 help
1424 Enabling this option turns a certain set of sanity checks for user
1425 copy operations into compile time failures.
1427 The copy_from_user() etc checks are there to help test if there
1428 are sufficient security checks on the length argument of
1429 the copy operation, by having gcc prove that the argument is
1430 within bounds.
1432 If unsure, say N.
1434 source kernel/trace/Kconfig
1436 menu "Runtime Testing"
1438 config LKDTM
1439 tristate "Linux Kernel Dump Test Tool Module"
1440 depends on DEBUG_FS
1441 depends on BLOCK
1442 default n
1443 help
1444 This module enables testing of the different dumping mechanisms by
1445 inducing system failures at predefined crash points.
1446 If you don't need it: say N
1447 Choose M here to compile this code as a module. The module will be
1448 called lkdtm.
1450 Documentation on how to use the module can be found in
1451 Documentation/fault-injection/provoke-crashes.txt
1453 config TEST_LIST_SORT
1454 bool "Linked list sorting test"
1455 depends on DEBUG_KERNEL
1456 help
1457 Enable this to turn on 'list_sort()' function test. This test is
1458 executed only once during system boot, so affects only boot time.
1460 If unsure, say N.
1462 config KPROBES_SANITY_TEST
1463 bool "Kprobes sanity tests"
1464 depends on DEBUG_KERNEL
1465 depends on KPROBES
1466 default n
1467 help
1468 This option provides for testing basic kprobes functionality on
1469 boot. A sample kprobe, jprobe and kretprobe are inserted and
1470 verified for functionality.
1472 Say N if you are unsure.
1474 config BACKTRACE_SELF_TEST
1475 tristate "Self test for the backtrace code"
1476 depends on DEBUG_KERNEL
1477 default n
1478 help
1479 This option provides a kernel module that can be used to test
1480 the kernel stack backtrace code. This option is not useful
1481 for distributions or general kernels, but only for kernel
1482 developers working on architecture code.
1484 Note that if you want to also test saved backtraces, you will
1485 have to enable STACKTRACE as well.
1487 Say N if you are unsure.
1489 config RBTREE_TEST
1490 tristate "Red-Black tree test"
1491 depends on DEBUG_KERNEL
1492 help
1493 A benchmark measuring the performance of the rbtree library.
1494 Also includes rbtree invariant checks.
1496 config INTERVAL_TREE_TEST
1497 tristate "Interval tree test"
1498 depends on m && DEBUG_KERNEL
1499 help
1500 A benchmark measuring the performance of the interval tree library
1502 config PERCPU_TEST
1503 tristate "Per cpu operations test"
1504 depends on m && DEBUG_KERNEL
1505 help
1506 Enable this option to build test module which validates per-cpu
1507 operations.
1509 If unsure, say N.
1511 config ATOMIC64_SELFTEST
1512 bool "Perform an atomic64_t self-test at boot"
1513 help
1514 Enable this option to test the atomic64_t functions at boot.
1516 If unsure, say N.
1518 config ASYNC_RAID6_TEST
1519 tristate "Self test for hardware accelerated raid6 recovery"
1520 depends on ASYNC_RAID6_RECOV
1521 select ASYNC_MEMCPY
1522 ---help---
1523 This is a one-shot self test that permutes through the
1524 recovery of all the possible two disk failure scenarios for a
1525 N-disk array. Recovery is performed with the asynchronous
1526 raid6 recovery routines, and will optionally use an offload
1527 engine if one is available.
1529 If unsure, say N.
1531 config TEST_STRING_HELPERS
1532 tristate "Test functions located in the string_helpers module at runtime"
1534 config TEST_KSTRTOX
1535 tristate "Test kstrto*() family of functions at runtime"
1537 endmenu # runtime tests
1539 config PROVIDE_OHCI1394_DMA_INIT
1540 bool "Remote debugging over FireWire early on boot"
1541 depends on PCI && X86
1542 help
1543 If you want to debug problems which hang or crash the kernel early
1544 on boot and the crashing machine has a FireWire port, you can use
1545 this feature to remotely access the memory of the crashed machine
1546 over FireWire. This employs remote DMA as part of the OHCI1394
1547 specification which is now the standard for FireWire controllers.
1549 With remote DMA, you can monitor the printk buffer remotely using
1550 firescope and access all memory below 4GB using fireproxy from gdb.
1551 Even controlling a kernel debugger is possible using remote DMA.
1553 Usage:
1555 If ohci1394_dma=early is used as boot parameter, it will initialize
1556 all OHCI1394 controllers which are found in the PCI config space.
1558 As all changes to the FireWire bus such as enabling and disabling
1559 devices cause a bus reset and thereby disable remote DMA for all
1560 devices, be sure to have the cable plugged and FireWire enabled on
1561 the debugging host before booting the debug target for debugging.
1563 This code (~1k) is freed after boot. By then, the firewire stack
1564 in charge of the OHCI-1394 controllers should be used instead.
1566 See Documentation/debugging-via-ohci1394.txt for more information.
1568 config BUILD_DOCSRC
1569 bool "Build targets in Documentation/ tree"
1570 depends on HEADERS_CHECK
1571 help
1572 This option attempts to build objects from the source files in the
1573 kernel Documentation/ tree.
1575 Say N if you are unsure.
1577 config DMA_API_DEBUG
1578 bool "Enable debugging of DMA-API usage"
1579 depends on HAVE_DMA_API_DEBUG
1580 help
1581 Enable this option to debug the use of the DMA API by device drivers.
1582 With this option you will be able to detect common bugs in device
1583 drivers like double-freeing of DMA mappings or freeing mappings that
1584 were never allocated.
1586 This also attempts to catch cases where a page owned by DMA is
1587 accessed by the cpu in a way that could cause data corruption. For
1588 example, this enables cow_user_page() to check that the source page is
1589 not undergoing DMA.
1591 This option causes a performance degradation. Use only if you want to
1592 debug device drivers and dma interactions.
1594 If unsure, say N.
1596 config TEST_MODULE
1597 tristate "Test module loading with 'hello world' module"
1598 default n
1599 depends on m
1600 help
1601 This builds the "test_module" module that emits "Hello, world"
1602 on printk when loaded. It is designed to be used for basic
1603 evaluation of the module loading subsystem (for example when
1604 validating module verification). It lacks any extra dependencies,
1605 and will not normally be loaded by the system unless explicitly
1606 requested by name.
1608 If unsure, say N.
1610 config TEST_USER_COPY
1611 tristate "Test user/kernel boundary protections"
1612 default n
1613 depends on m
1614 help
1615 This builds the "test_user_copy" module that runs sanity checks
1616 on the copy_to/from_user infrastructure, making sure basic
1617 user/kernel boundary testing is working. If it fails to load,
1618 a regression has been detected in the user/kernel memory boundary
1619 protections.
1621 If unsure, say N.
1623 source "samples/Kconfig"
1625 source "lib/Kconfig.kgdb"