| blob | 7a638aa3545bfa7d409dfa5110bc060acfd381a5 |
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_VMACACHE
505 bool "Debug VMA caching"
506 depends on DEBUG_VM
507 help
508 Enable this to turn on VMA caching debug information. Doing so
509 can cause significant overhead, so only enable it in non-production
510 environments.
512 If unsure, say N.
514 config DEBUG_VM_RB
515 bool "Debug VM red-black trees"
516 depends on DEBUG_VM
517 help
518 Enable VM red-black tree debugging information and extra validations.
520 If unsure, say N.
522 config DEBUG_VIRTUAL
523 bool "Debug VM translations"
524 depends on DEBUG_KERNEL && X86
525 help
526 Enable some costly sanity checks in virtual to page code. This can
527 catch mistakes with virt_to_page() and friends.
529 If unsure, say N.
531 config DEBUG_NOMMU_REGIONS
532 bool "Debug the global anon/private NOMMU mapping region tree"
533 depends on DEBUG_KERNEL && !MMU
534 help
535 This option causes the global tree of anonymous and private mapping
536 regions to be regularly checked for invalid topology.
538 config DEBUG_MEMORY_INIT
539 bool "Debug memory initialisation" if EXPERT
540 default !EXPERT
541 help
542 Enable this for additional checks during memory initialisation.
543 The sanity checks verify aspects of the VM such as the memory model
544 and other information provided by the architecture. Verbose
545 information will be printed at KERN_DEBUG loglevel depending
546 on the mminit_loglevel= command-line option.
548 If unsure, say Y
550 config MEMORY_NOTIFIER_ERROR_INJECT
551 tristate "Memory hotplug notifier error injection module"
552 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
553 help
554 This option provides the ability to inject artificial errors to
555 memory hotplug notifier chain callbacks. It is controlled through
556 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
558 If the notifier call chain should be failed with some events
559 notified, write the error code to "actions/<notifier event>/error".
561 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
563 # cd /sys/kernel/debug/notifier-error-inject/memory
564 # echo -12 > actions/MEM_GOING_OFFLINE/error
565 # echo offline > /sys/devices/system/memory/memoryXXX/state
566 bash: echo: write error: Cannot allocate memory
568 To compile this code as a module, choose M here: the module will
569 be called memory-notifier-error-inject.
571 If unsure, say N.
573 config DEBUG_PER_CPU_MAPS
574 bool "Debug access to per_cpu maps"
575 depends on DEBUG_KERNEL
576 depends on SMP
577 help
578 Say Y to verify that the per_cpu map being accessed has
579 been set up. This adds a fair amount of code to kernel memory
580 and decreases performance.
582 Say N if unsure.
584 config DEBUG_HIGHMEM
585 bool "Highmem debugging"
586 depends on DEBUG_KERNEL && HIGHMEM
587 help
588 This option enables additional error checking for high memory
589 systems. Disable for production systems.
591 config HAVE_DEBUG_STACKOVERFLOW
592 bool
594 config DEBUG_STACKOVERFLOW
595 bool "Check for stack overflows"
596 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
597 ---help---
598 Say Y here if you want to check for overflows of kernel, IRQ
599 and exception stacks (if your archicture uses them). This
600 option will show detailed messages if free stack space drops
601 below a certain limit.
603 These kinds of bugs usually occur when call-chains in the
604 kernel get too deep, especially when interrupts are
605 involved.
607 Use this in cases where you see apparently random memory
608 corruption, especially if it appears in 'struct thread_info'
610 If in doubt, say "N".
612 source "lib/Kconfig.kmemcheck"
614 endmenu # "Memory Debugging"
616 config DEBUG_SHIRQ
617 bool "Debug shared IRQ handlers"
618 depends on DEBUG_KERNEL
619 help
620 Enable this to generate a spurious interrupt as soon as a shared
621 interrupt handler is registered, and just before one is deregistered.
622 Drivers ought to be able to handle interrupts coming in at those
623 points; some don't and need to be caught.
625 menu "Debug Lockups and Hangs"
627 config LOCKUP_DETECTOR
628 bool "Detect Hard and Soft Lockups"
629 depends on DEBUG_KERNEL && !S390
630 help
631 Say Y here to enable the kernel to act as a watchdog to detect
632 hard and soft lockups.
634 Softlockups are bugs that cause the kernel to loop in kernel
635 mode for more than 20 seconds, without giving other tasks a
636 chance to run. The current stack trace is displayed upon
637 detection and the system will stay locked up.
639 Hardlockups are bugs that cause the CPU to loop in kernel mode
640 for more than 10 seconds, without letting other interrupts have a
641 chance to run. The current stack trace is displayed upon detection
642 and the system will stay locked up.
644 The overhead should be minimal. A periodic hrtimer runs to
645 generate interrupts and kick the watchdog task every 4 seconds.
646 An NMI is generated every 10 seconds or so to check for hardlockups.
648 The frequency of hrtimer and NMI events and the soft and hard lockup
649 thresholds can be controlled through the sysctl watchdog_thresh.
651 config HARDLOCKUP_DETECTOR
652 def_bool y
653 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
654 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
656 config BOOTPARAM_HARDLOCKUP_PANIC
657 bool "Panic (Reboot) On Hard Lockups"
658 depends on HARDLOCKUP_DETECTOR
659 help
660 Say Y here to enable the kernel to panic on "hard lockups",
661 which are bugs that cause the kernel to loop in kernel
662 mode with interrupts disabled for more than 10 seconds (configurable
663 using the watchdog_thresh sysctl).
665 Say N if unsure.
667 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
668 int
669 depends on HARDLOCKUP_DETECTOR
670 range 0 1
671 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
672 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
674 config BOOTPARAM_SOFTLOCKUP_PANIC
675 bool "Panic (Reboot) On Soft Lockups"
676 depends on LOCKUP_DETECTOR
677 help
678 Say Y here to enable the kernel to panic on "soft lockups",
679 which are bugs that cause the kernel to loop in kernel
680 mode for more than 20 seconds (configurable using the watchdog_thresh
681 sysctl), without giving other tasks a chance to run.
683 The panic can be used in combination with panic_timeout,
684 to cause the system to reboot automatically after a
685 lockup has been detected. This feature is useful for
686 high-availability systems that have uptime guarantees and
687 where a lockup must be resolved ASAP.
689 Say N if unsure.
691 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
692 int
693 depends on LOCKUP_DETECTOR
694 range 0 1
695 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
696 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
698 config DETECT_HUNG_TASK
699 bool "Detect Hung Tasks"
700 depends on DEBUG_KERNEL
701 default LOCKUP_DETECTOR
702 help
703 Say Y here to enable the kernel to detect "hung tasks",
704 which are bugs that cause the task to be stuck in
705 uninterruptible "D" state indefinitiley.
707 When a hung task is detected, the kernel will print the
708 current stack trace (which you should report), but the
709 task will stay in uninterruptible state. If lockdep is
710 enabled then all held locks will also be reported. This
711 feature has negligible overhead.
713 config DEFAULT_HUNG_TASK_TIMEOUT
714 int "Default timeout for hung task detection (in seconds)"
715 depends on DETECT_HUNG_TASK
716 default 120
717 help
718 This option controls the default timeout (in seconds) used
719 to determine when a task has become non-responsive and should
720 be considered hung.
722 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
723 sysctl or by writing a value to
724 /proc/sys/kernel/hung_task_timeout_secs.
726 A timeout of 0 disables the check. The default is two minutes.
727 Keeping the default should be fine in most cases.
729 config BOOTPARAM_HUNG_TASK_PANIC
730 bool "Panic (Reboot) On Hung Tasks"
731 depends on DETECT_HUNG_TASK
732 help
733 Say Y here to enable the kernel to panic on "hung tasks",
734 which are bugs that cause the kernel to leave a task stuck
735 in uninterruptible "D" state.
737 The panic can be used in combination with panic_timeout,
738 to cause the system to reboot automatically after a
739 hung task has been detected. This feature is useful for
740 high-availability systems that have uptime guarantees and
741 where a hung tasks must be resolved ASAP.
743 Say N if unsure.
745 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
746 int
747 depends on DETECT_HUNG_TASK
748 range 0 1
749 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
750 default 1 if BOOTPARAM_HUNG_TASK_PANIC
752 endmenu # "Debug lockups and hangs"
754 config PANIC_ON_OOPS
755 bool "Panic on Oops"
756 help
757 Say Y here to enable the kernel to panic when it oopses. This
758 has the same effect as setting oops=panic on the kernel command
759 line.
761 This feature is useful to ensure that the kernel does not do
762 anything erroneous after an oops which could result in data
763 corruption or other issues.
765 Say N if unsure.
767 config PANIC_ON_OOPS_VALUE
768 int
769 range 0 1
770 default 0 if !PANIC_ON_OOPS
771 default 1 if PANIC_ON_OOPS
773 config PANIC_TIMEOUT
774 int "panic timeout"
775 default 0
776 help
777 Set the timeout value (in seconds) until a reboot occurs when the
778 the kernel panics. If n = 0, then we wait forever. A timeout
779 value n > 0 will wait n seconds before rebooting, while a timeout
780 value n < 0 will reboot immediately.
782 config SCHED_DEBUG
783 bool "Collect scheduler debugging info"
784 depends on DEBUG_KERNEL && PROC_FS
785 default y
786 help
787 If you say Y here, the /proc/sched_debug file will be provided
788 that can help debug the scheduler. The runtime overhead of this
789 option is minimal.
791 config SCHEDSTATS
792 bool "Collect scheduler statistics"
793 depends on DEBUG_KERNEL && PROC_FS
794 help
795 If you say Y here, additional code will be inserted into the
796 scheduler and related routines to collect statistics about
797 scheduler behavior and provide them in /proc/schedstat. These
798 stats may be useful for both tuning and debugging the scheduler
799 If you aren't debugging the scheduler or trying to tune a specific
800 application, you can say N to avoid the very slight overhead
801 this adds.
803 config TIMER_STATS
804 bool "Collect kernel timers statistics"
805 depends on DEBUG_KERNEL && PROC_FS
806 help
807 If you say Y here, additional code will be inserted into the
808 timer routines to collect statistics about kernel timers being
809 reprogrammed. The statistics can be read from /proc/timer_stats.
810 The statistics collection is started by writing 1 to /proc/timer_stats,
811 writing 0 stops it. This feature is useful to collect information
812 about timer usage patterns in kernel and userspace. This feature
813 is lightweight if enabled in the kernel config but not activated
814 (it defaults to deactivated on bootup and will only be activated
815 if some application like powertop activates it explicitly).
817 config DEBUG_PREEMPT
818 bool "Debug preemptible kernel"
819 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
820 default y
821 help
822 If you say Y here then the kernel will use a debug variant of the
823 commonly used smp_processor_id() function and will print warnings
824 if kernel code uses it in a preemption-unsafe way. Also, the kernel
825 will detect preemption count underflows.
827 menu "Lock Debugging (spinlocks, mutexes, etc...)"
829 config DEBUG_RT_MUTEXES
830 bool "RT Mutex debugging, deadlock detection"
831 depends on DEBUG_KERNEL && RT_MUTEXES
832 help
833 This allows rt mutex semantics violations and rt mutex related
834 deadlocks (lockups) to be detected and reported automatically.
836 config RT_MUTEX_TESTER
837 bool "Built-in scriptable tester for rt-mutexes"
838 depends on DEBUG_KERNEL && RT_MUTEXES
839 help
840 This option enables a rt-mutex tester.
842 config DEBUG_SPINLOCK
843 bool "Spinlock and rw-lock debugging: basic checks"
844 depends on DEBUG_KERNEL
845 select UNINLINE_SPIN_UNLOCK
846 help
847 Say Y here and build SMP to catch missing spinlock initialization
848 and certain other kinds of spinlock errors commonly made. This is
849 best used in conjunction with the NMI watchdog so that spinlock
850 deadlocks are also debuggable.
852 config DEBUG_MUTEXES
853 bool "Mutex debugging: basic checks"
854 depends on DEBUG_KERNEL
855 help
856 This feature allows mutex semantics violations to be detected and
857 reported.
859 config DEBUG_WW_MUTEX_SLOWPATH
860 bool "Wait/wound mutex debugging: Slowpath testing"
861 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
862 select DEBUG_LOCK_ALLOC
863 select DEBUG_SPINLOCK
864 select DEBUG_MUTEXES
865 help
866 This feature enables slowpath testing for w/w mutex users by
867 injecting additional -EDEADLK wound/backoff cases. Together with
868 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
869 will test all possible w/w mutex interface abuse with the
870 exception of simply not acquiring all the required locks.
872 config DEBUG_LOCK_ALLOC
873 bool "Lock debugging: detect incorrect freeing of live locks"
874 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
875 select DEBUG_SPINLOCK
876 select DEBUG_MUTEXES
877 select LOCKDEP
878 help
879 This feature will check whether any held lock (spinlock, rwlock,
880 mutex or rwsem) is incorrectly freed by the kernel, via any of the
881 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
882 vfree(), etc.), whether a live lock is incorrectly reinitialized via
883 spin_lock_init()/mutex_init()/etc., or whether there is any lock
884 held during task exit.
886 config PROVE_LOCKING
887 bool "Lock debugging: prove locking correctness"
888 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
889 select LOCKDEP
890 select DEBUG_SPINLOCK
891 select DEBUG_MUTEXES
892 select DEBUG_LOCK_ALLOC
893 select TRACE_IRQFLAGS
894 default n
895 help
896 This feature enables the kernel to prove that all locking
897 that occurs in the kernel runtime is mathematically
898 correct: that under no circumstance could an arbitrary (and
899 not yet triggered) combination of observed locking
900 sequences (on an arbitrary number of CPUs, running an
901 arbitrary number of tasks and interrupt contexts) cause a
902 deadlock.
904 In short, this feature enables the kernel to report locking
905 related deadlocks before they actually occur.
907 The proof does not depend on how hard and complex a
908 deadlock scenario would be to trigger: how many
909 participant CPUs, tasks and irq-contexts would be needed
910 for it to trigger. The proof also does not depend on
911 timing: if a race and a resulting deadlock is possible
912 theoretically (no matter how unlikely the race scenario
913 is), it will be proven so and will immediately be
914 reported by the kernel (once the event is observed that
915 makes the deadlock theoretically possible).
917 If a deadlock is impossible (i.e. the locking rules, as
918 observed by the kernel, are mathematically correct), the
919 kernel reports nothing.
921 NOTE: this feature can also be enabled for rwlocks, mutexes
922 and rwsems - in which case all dependencies between these
923 different locking variants are observed and mapped too, and
924 the proof of observed correctness is also maintained for an
925 arbitrary combination of these separate locking variants.
927 For more details, see Documentation/lockdep-design.txt.
929 config LOCKDEP
930 bool
931 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
932 select STACKTRACE
933 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
934 select KALLSYMS
935 select KALLSYMS_ALL
937 config LOCK_STAT
938 bool "Lock usage statistics"
939 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
940 select LOCKDEP
941 select DEBUG_SPINLOCK
942 select DEBUG_MUTEXES
943 select DEBUG_LOCK_ALLOC
944 default n
945 help
946 This feature enables tracking lock contention points
948 For more details, see Documentation/lockstat.txt
950 This also enables lock events required by "perf lock",
951 subcommand of perf.
952 If you want to use "perf lock", you also need to turn on
953 CONFIG_EVENT_TRACING.
955 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
956 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
958 config DEBUG_LOCKDEP
959 bool "Lock dependency engine debugging"
960 depends on DEBUG_KERNEL && LOCKDEP
961 help
962 If you say Y here, the lock dependency engine will do
963 additional runtime checks to debug itself, at the price
964 of more runtime overhead.
966 config DEBUG_ATOMIC_SLEEP
967 bool "Sleep inside atomic section checking"
968 select PREEMPT_COUNT
969 depends on DEBUG_KERNEL
970 help
971 If you say Y here, various routines which may sleep will become very
972 noisy if they are called inside atomic sections: when a spinlock is
973 held, inside an rcu read side critical section, inside preempt disabled
974 sections, inside an interrupt, etc...
976 config DEBUG_LOCKING_API_SELFTESTS
977 bool "Locking API boot-time self-tests"
978 depends on DEBUG_KERNEL
979 help
980 Say Y here if you want the kernel to run a short self-test during
981 bootup. The self-test checks whether common types of locking bugs
982 are detected by debugging mechanisms or not. (if you disable
983 lock debugging then those bugs wont be detected of course.)
984 The following locking APIs are covered: spinlocks, rwlocks,
985 mutexes and rwsems.
987 config LOCK_TORTURE_TEST
988 tristate "torture tests for locking"
989 depends on DEBUG_KERNEL
990 select TORTURE_TEST
991 default n
992 help
993 This option provides a kernel module that runs torture tests
994 on kernel locking primitives. The kernel module may be built
995 after the fact on the running kernel to be tested, if desired.
997 Say Y here if you want kernel locking-primitive torture tests
998 to be built into the kernel.
999 Say M if you want these torture tests to build as a module.
1000 Say N if you are unsure.
1002 endmenu # lock debugging
1004 config TRACE_IRQFLAGS
1005 bool
1006 help
1007 Enables hooks to interrupt enabling and disabling for
1008 either tracing or lock debugging.
1010 config STACKTRACE
1011 bool
1012 depends on STACKTRACE_SUPPORT
1014 config DEBUG_KOBJECT
1015 bool "kobject debugging"
1016 depends on DEBUG_KERNEL
1017 help
1018 If you say Y here, some extra kobject debugging messages will be sent
1019 to the syslog.
1021 config DEBUG_KOBJECT_RELEASE
1022 bool "kobject release debugging"
1023 depends on DEBUG_OBJECTS_TIMERS
1024 help
1025 kobjects are reference counted objects. This means that their
1026 last reference count put is not predictable, and the kobject can
1027 live on past the point at which a driver decides to drop it's
1028 initial reference to the kobject gained on allocation. An
1029 example of this would be a struct device which has just been
1030 unregistered.
1032 However, some buggy drivers assume that after such an operation,
1033 the memory backing the kobject can be immediately freed. This
1034 goes completely against the principles of a refcounted object.
1036 If you say Y here, the kernel will delay the release of kobjects
1037 on the last reference count to improve the visibility of this
1038 kind of kobject release bug.
1040 config HAVE_DEBUG_BUGVERBOSE
1041 bool
1043 config DEBUG_BUGVERBOSE
1044 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1045 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1046 default y
1047 help
1048 Say Y here to make BUG() panics output the file name and line number
1049 of the BUG call as well as the EIP and oops trace. This aids
1050 debugging but costs about 70-100K of memory.
1052 config DEBUG_LIST
1053 bool "Debug linked list manipulation"
1054 depends on DEBUG_KERNEL
1055 help
1056 Enable this to turn on extended checks in the linked-list
1057 walking routines.
1059 If unsure, say N.
1061 config DEBUG_PI_LIST
1062 bool "Debug priority linked list manipulation"
1063 depends on DEBUG_KERNEL
1064 help
1065 Enable this to turn on extended checks in the priority-ordered
1066 linked-list (plist) walking routines. This checks the entire
1067 list multiple times during each manipulation.
1069 If unsure, say N.
1071 config DEBUG_SG
1072 bool "Debug SG table operations"
1073 depends on DEBUG_KERNEL
1074 help
1075 Enable this to turn on checks on scatter-gather tables. This can
1076 help find problems with drivers that do not properly initialize
1077 their sg tables.
1079 If unsure, say N.
1081 config DEBUG_NOTIFIERS
1082 bool "Debug notifier call chains"
1083 depends on DEBUG_KERNEL
1084 help
1085 Enable this to turn on sanity checking for notifier call chains.
1086 This is most useful for kernel developers to make sure that
1087 modules properly unregister themselves from notifier chains.
1088 This is a relatively cheap check but if you care about maximum
1089 performance, say N.
1091 config DEBUG_CREDENTIALS
1092 bool "Debug credential management"
1093 depends on DEBUG_KERNEL
1094 help
1095 Enable this to turn on some debug checking for credential
1096 management. The additional code keeps track of the number of
1097 pointers from task_structs to any given cred struct, and checks to
1098 see that this number never exceeds the usage count of the cred
1099 struct.
1101 Furthermore, if SELinux is enabled, this also checks that the
1102 security pointer in the cred struct is never seen to be invalid.
1104 If unsure, say N.
1106 menu "RCU Debugging"
1108 config PROVE_RCU
1109 bool "RCU debugging: prove RCU correctness"
1110 depends on PROVE_LOCKING
1111 default n
1112 help
1113 This feature enables lockdep extensions that check for correct
1114 use of RCU APIs. This is currently under development. Say Y
1115 if you want to debug RCU usage or help work on the PROVE_RCU
1116 feature.
1118 Say N if you are unsure.
1120 config PROVE_RCU_REPEATEDLY
1121 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1122 depends on PROVE_RCU
1123 default n
1124 help
1125 By itself, PROVE_RCU will disable checking upon issuing the
1126 first warning (or "splat"). This feature prevents such
1127 disabling, allowing multiple RCU-lockdep warnings to be printed
1128 on a single reboot.
1130 Say Y to allow multiple RCU-lockdep warnings per boot.
1132 Say N if you are unsure.
1134 config PROVE_RCU_DELAY
1135 bool "RCU debugging: preemptible RCU race provocation"
1136 depends on DEBUG_KERNEL && PREEMPT_RCU
1137 default n
1138 help
1139 There is a class of races that involve an unlikely preemption
1140 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
1141 been set to INT_MIN. This feature inserts a delay at that
1142 point to increase the probability of these races.
1144 Say Y to increase probability of preemption of __rcu_read_unlock().
1146 Say N if you are unsure.
1148 config SPARSE_RCU_POINTER
1149 bool "RCU debugging: sparse-based checks for pointer usage"
1150 default n
1151 help
1152 This feature enables the __rcu sparse annotation for
1153 RCU-protected pointers. This annotation will cause sparse
1154 to flag any non-RCU used of annotated pointers. This can be
1155 helpful when debugging RCU usage. Please note that this feature
1156 is not intended to enforce code cleanliness; it is instead merely
1157 a debugging aid.
1159 Say Y to make sparse flag questionable use of RCU-protected pointers
1161 Say N if you are unsure.
1163 config TORTURE_TEST
1164 tristate
1165 default n
1167 config RCU_TORTURE_TEST
1168 tristate "torture tests for RCU"
1169 depends on DEBUG_KERNEL
1170 select TORTURE_TEST
1171 default n
1172 help
1173 This option provides a kernel module that runs torture tests
1174 on the RCU infrastructure. The kernel module may be built
1175 after the fact on the running kernel to be tested, if desired.
1177 Say Y here if you want RCU torture tests to be built into
1178 the kernel.
1179 Say M if you want the RCU torture tests to build as a module.
1180 Say N if you are unsure.
1182 config RCU_TORTURE_TEST_RUNNABLE
1183 bool "torture tests for RCU runnable by default"
1184 depends on RCU_TORTURE_TEST = y
1185 default n
1186 help
1187 This option provides a way to build the RCU torture tests
1188 directly into the kernel without them starting up at boot
1189 time. You can use /proc/sys/kernel/rcutorture_runnable
1190 to manually override this setting. This /proc file is
1191 available only when the RCU torture tests have been built
1192 into the kernel.
1194 Say Y here if you want the RCU torture tests to start during
1195 boot (you probably don't).
1196 Say N here if you want the RCU torture tests to start only
1197 after being manually enabled via /proc.
1199 config RCU_CPU_STALL_TIMEOUT
1200 int "RCU CPU stall timeout in seconds"
1201 depends on RCU_STALL_COMMON
1202 range 3 300
1203 default 21
1204 help
1205 If a given RCU grace period extends more than the specified
1206 number of seconds, a CPU stall warning is printed. If the
1207 RCU grace period persists, additional CPU stall warnings are
1208 printed at more widely spaced intervals.
1210 config RCU_CPU_STALL_VERBOSE
1211 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
1212 depends on TREE_PREEMPT_RCU
1213 default y
1214 help
1215 This option causes RCU to printk detailed per-task information
1216 for any tasks that are stalling the current RCU grace period.
1218 Say N if you are unsure.
1220 Say Y if you want to enable such checks.
1222 config RCU_CPU_STALL_INFO
1223 bool "Print additional diagnostics on RCU CPU stall"
1224 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1225 default n
1226 help
1227 For each stalled CPU that is aware of the current RCU grace
1228 period, print out additional per-CPU diagnostic information
1229 regarding scheduling-clock ticks, idle state, and,
1230 for RCU_FAST_NO_HZ kernels, idle-entry state.
1232 Say N if you are unsure.
1234 Say Y if you want to enable such diagnostics.
1236 config RCU_TRACE
1237 bool "Enable tracing for RCU"
1238 depends on DEBUG_KERNEL
1239 select TRACE_CLOCK
1240 help
1241 This option provides tracing in RCU which presents stats
1242 in debugfs for debugging RCU implementation.
1244 Say Y here if you want to enable RCU tracing
1245 Say N if you are unsure.
1247 endmenu # "RCU Debugging"
1249 config DEBUG_BLOCK_EXT_DEVT
1250 bool "Force extended block device numbers and spread them"
1251 depends on DEBUG_KERNEL
1252 depends on BLOCK
1253 default n
1254 help
1255 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1256 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1257 YOU ARE DOING. Distros, please enable this and fix whatever
1258 is broken.
1260 Conventionally, block device numbers are allocated from
1261 predetermined contiguous area. However, extended block area
1262 may introduce non-contiguous block device numbers. This
1263 option forces most block device numbers to be allocated from
1264 the extended space and spreads them to discover kernel or
1265 userland code paths which assume predetermined contiguous
1266 device number allocation.
1268 Note that turning on this debug option shuffles all the
1269 device numbers for all IDE and SCSI devices including libata
1270 ones, so root partition specified using device number
1271 directly (via rdev or root=MAJ:MIN) won't work anymore.
1272 Textual device names (root=/dev/sdXn) will continue to work.
1274 Say N if you are unsure.
1276 config NOTIFIER_ERROR_INJECTION
1277 tristate "Notifier error injection"
1278 depends on DEBUG_KERNEL
1279 select DEBUG_FS
1280 help
1281 This option provides the ability to inject artificial errors to
1282 specified notifier chain callbacks. It is useful to test the error
1283 handling of notifier call chain failures.
1285 Say N if unsure.
1287 config CPU_NOTIFIER_ERROR_INJECT
1288 tristate "CPU notifier error injection module"
1289 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1290 help
1291 This option provides a kernel module that can be used to test
1292 the error handling of the cpu notifiers by injecting artificial
1293 errors to CPU notifier chain callbacks. It is controlled through
1294 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1296 If the notifier call chain should be failed with some events
1297 notified, write the error code to "actions/<notifier event>/error".
1299 Example: Inject CPU offline error (-1 == -EPERM)
1301 # cd /sys/kernel/debug/notifier-error-inject/cpu
1302 # echo -1 > actions/CPU_DOWN_PREPARE/error
1303 # echo 0 > /sys/devices/system/cpu/cpu1/online
1304 bash: echo: write error: Operation not permitted
1306 To compile this code as a module, choose M here: the module will
1307 be called cpu-notifier-error-inject.
1309 If unsure, say N.
1311 config PM_NOTIFIER_ERROR_INJECT
1312 tristate "PM notifier error injection module"
1313 depends on PM && NOTIFIER_ERROR_INJECTION
1314 default m if PM_DEBUG
1315 help
1316 This option provides the ability to inject artificial errors to
1317 PM notifier chain callbacks. It is controlled through debugfs
1318 interface /sys/kernel/debug/notifier-error-inject/pm
1320 If the notifier call chain should be failed with some events
1321 notified, write the error code to "actions/<notifier event>/error".
1323 Example: Inject PM suspend error (-12 = -ENOMEM)
1325 # cd /sys/kernel/debug/notifier-error-inject/pm/
1326 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1327 # echo mem > /sys/power/state
1328 bash: echo: write error: Cannot allocate memory
1330 To compile this code as a module, choose M here: the module will
1331 be called pm-notifier-error-inject.
1333 If unsure, say N.
1335 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1336 tristate "OF reconfig notifier error injection module"
1337 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1338 help
1339 This option provides the ability to inject artificial errors to
1340 OF reconfig notifier chain callbacks. It is controlled
1341 through debugfs interface under
1342 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1344 If the notifier call chain should be failed with some events
1345 notified, write the error code to "actions/<notifier event>/error".
1347 To compile this code as a module, choose M here: the module will
1348 be called of-reconfig-notifier-error-inject.
1350 If unsure, say N.
1352 config FAULT_INJECTION
1353 bool "Fault-injection framework"
1354 depends on DEBUG_KERNEL
1355 help
1356 Provide fault-injection framework.
1357 For more details, see Documentation/fault-injection/.
1359 config FAILSLAB
1360 bool "Fault-injection capability for kmalloc"
1361 depends on FAULT_INJECTION
1362 depends on SLAB || SLUB
1363 help
1364 Provide fault-injection capability for kmalloc.
1366 config FAIL_PAGE_ALLOC
1367 bool "Fault-injection capabilitiy for alloc_pages()"
1368 depends on FAULT_INJECTION
1369 help
1370 Provide fault-injection capability for alloc_pages().
1372 config FAIL_MAKE_REQUEST
1373 bool "Fault-injection capability for disk IO"
1374 depends on FAULT_INJECTION && BLOCK
1375 help
1376 Provide fault-injection capability for disk IO.
1378 config FAIL_IO_TIMEOUT
1379 bool "Fault-injection capability for faking disk interrupts"
1380 depends on FAULT_INJECTION && BLOCK
1381 help
1382 Provide fault-injection capability on end IO handling. This
1383 will make the block layer "forget" an interrupt as configured,
1384 thus exercising the error handling.
1386 Only works with drivers that use the generic timeout handling,
1387 for others it wont do anything.
1389 config FAIL_MMC_REQUEST
1390 bool "Fault-injection capability for MMC IO"
1391 select DEBUG_FS
1392 depends on FAULT_INJECTION && MMC
1393 help
1394 Provide fault-injection capability for MMC IO.
1395 This will make the mmc core return data errors. This is
1396 useful to test the error handling in the mmc block device
1397 and to test how the mmc host driver handles retries from
1398 the block device.
1400 config FAULT_INJECTION_DEBUG_FS
1401 bool "Debugfs entries for fault-injection capabilities"
1402 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1403 help
1404 Enable configuration of fault-injection capabilities via debugfs.
1406 config FAULT_INJECTION_STACKTRACE_FILTER
1407 bool "stacktrace filter for fault-injection capabilities"
1408 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1409 depends on !X86_64
1410 select STACKTRACE
1411 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1412 help
1413 Provide stacktrace filter for fault-injection capabilities
1415 config LATENCYTOP
1416 bool "Latency measuring infrastructure"
1417 depends on HAVE_LATENCYTOP_SUPPORT
1418 depends on DEBUG_KERNEL
1419 depends on STACKTRACE_SUPPORT
1420 depends on PROC_FS
1421 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1422 select KALLSYMS
1423 select KALLSYMS_ALL
1424 select STACKTRACE
1425 select SCHEDSTATS
1426 select SCHED_DEBUG
1427 help
1428 Enable this option if you want to use the LatencyTOP tool
1429 to find out which userspace is blocking on what kernel operations.
1431 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1432 bool
1434 config DEBUG_STRICT_USER_COPY_CHECKS
1435 bool "Strict user copy size checks"
1436 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1437 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1438 help
1439 Enabling this option turns a certain set of sanity checks for user
1440 copy operations into compile time failures.
1442 The copy_from_user() etc checks are there to help test if there
1443 are sufficient security checks on the length argument of
1444 the copy operation, by having gcc prove that the argument is
1445 within bounds.
1447 If unsure, say N.
1449 source kernel/trace/Kconfig
1451 menu "Runtime Testing"
1453 config LKDTM
1454 tristate "Linux Kernel Dump Test Tool Module"
1455 depends on DEBUG_FS
1456 depends on BLOCK
1457 default n
1458 help
1459 This module enables testing of the different dumping mechanisms by
1460 inducing system failures at predefined crash points.
1461 If you don't need it: say N
1462 Choose M here to compile this code as a module. The module will be
1463 called lkdtm.
1465 Documentation on how to use the module can be found in
1466 Documentation/fault-injection/provoke-crashes.txt
1468 config TEST_LIST_SORT
1469 bool "Linked list sorting test"
1470 depends on DEBUG_KERNEL
1471 help
1472 Enable this to turn on 'list_sort()' function test. This test is
1473 executed only once during system boot, so affects only boot time.
1475 If unsure, say N.
1477 config KPROBES_SANITY_TEST
1478 bool "Kprobes sanity tests"
1479 depends on DEBUG_KERNEL
1480 depends on KPROBES
1481 default n
1482 help
1483 This option provides for testing basic kprobes functionality on
1484 boot. A sample kprobe, jprobe and kretprobe are inserted and
1485 verified for functionality.
1487 Say N if you are unsure.
1489 config BACKTRACE_SELF_TEST
1490 tristate "Self test for the backtrace code"
1491 depends on DEBUG_KERNEL
1492 default n
1493 help
1494 This option provides a kernel module that can be used to test
1495 the kernel stack backtrace code. This option is not useful
1496 for distributions or general kernels, but only for kernel
1497 developers working on architecture code.
1499 Note that if you want to also test saved backtraces, you will
1500 have to enable STACKTRACE as well.
1502 Say N if you are unsure.
1504 config RBTREE_TEST
1505 tristate "Red-Black tree test"
1506 depends on DEBUG_KERNEL
1507 help
1508 A benchmark measuring the performance of the rbtree library.
1509 Also includes rbtree invariant checks.
1511 config INTERVAL_TREE_TEST
1512 tristate "Interval tree test"
1513 depends on m && DEBUG_KERNEL
1514 select INTERVAL_TREE
1515 help
1516 A benchmark measuring the performance of the interval tree library
1518 config PERCPU_TEST
1519 tristate "Per cpu operations test"
1520 depends on m && DEBUG_KERNEL
1521 help
1522 Enable this option to build test module which validates per-cpu
1523 operations.
1525 If unsure, say N.
1527 config ATOMIC64_SELFTEST
1528 bool "Perform an atomic64_t self-test at boot"
1529 help
1530 Enable this option to test the atomic64_t functions at boot.
1532 If unsure, say N.
1534 config ASYNC_RAID6_TEST
1535 tristate "Self test for hardware accelerated raid6 recovery"
1536 depends on ASYNC_RAID6_RECOV
1537 select ASYNC_MEMCPY
1538 ---help---
1539 This is a one-shot self test that permutes through the
1540 recovery of all the possible two disk failure scenarios for a
1541 N-disk array. Recovery is performed with the asynchronous
1542 raid6 recovery routines, and will optionally use an offload
1543 engine if one is available.
1545 If unsure, say N.
1547 config TEST_STRING_HELPERS
1548 tristate "Test functions located in the string_helpers module at runtime"
1550 config TEST_KSTRTOX
1551 tristate "Test kstrto*() family of functions at runtime"
1553 endmenu # runtime tests
1555 config PROVIDE_OHCI1394_DMA_INIT
1556 bool "Remote debugging over FireWire early on boot"
1557 depends on PCI && X86
1558 help
1559 If you want to debug problems which hang or crash the kernel early
1560 on boot and the crashing machine has a FireWire port, you can use
1561 this feature to remotely access the memory of the crashed machine
1562 over FireWire. This employs remote DMA as part of the OHCI1394
1563 specification which is now the standard for FireWire controllers.
1565 With remote DMA, you can monitor the printk buffer remotely using
1566 firescope and access all memory below 4GB using fireproxy from gdb.
1567 Even controlling a kernel debugger is possible using remote DMA.
1569 Usage:
1571 If ohci1394_dma=early is used as boot parameter, it will initialize
1572 all OHCI1394 controllers which are found in the PCI config space.
1574 As all changes to the FireWire bus such as enabling and disabling
1575 devices cause a bus reset and thereby disable remote DMA for all
1576 devices, be sure to have the cable plugged and FireWire enabled on
1577 the debugging host before booting the debug target for debugging.
1579 This code (~1k) is freed after boot. By then, the firewire stack
1580 in charge of the OHCI-1394 controllers should be used instead.
1582 See Documentation/debugging-via-ohci1394.txt for more information.
1584 config BUILD_DOCSRC
1585 bool "Build targets in Documentation/ tree"
1586 depends on HEADERS_CHECK
1587 help
1588 This option attempts to build objects from the source files in the
1589 kernel Documentation/ tree.
1591 Say N if you are unsure.
1593 config DMA_API_DEBUG
1594 bool "Enable debugging of DMA-API usage"
1595 depends on HAVE_DMA_API_DEBUG
1596 help
1597 Enable this option to debug the use of the DMA API by device drivers.
1598 With this option you will be able to detect common bugs in device
1599 drivers like double-freeing of DMA mappings or freeing mappings that
1600 were never allocated.
1602 This also attempts to catch cases where a page owned by DMA is
1603 accessed by the cpu in a way that could cause data corruption. For
1604 example, this enables cow_user_page() to check that the source page is
1605 not undergoing DMA.
1607 This option causes a performance degradation. Use only if you want to
1608 debug device drivers and dma interactions.
1610 If unsure, say N.
1612 config TEST_MODULE
1613 tristate "Test module loading with 'hello world' module"
1614 default n
1615 depends on m
1616 help
1617 This builds the "test_module" module that emits "Hello, world"
1618 on printk when loaded. It is designed to be used for basic
1619 evaluation of the module loading subsystem (for example when
1620 validating module verification). It lacks any extra dependencies,
1621 and will not normally be loaded by the system unless explicitly
1622 requested by name.
1624 If unsure, say N.
1626 config TEST_USER_COPY
1627 tristate "Test user/kernel boundary protections"
1628 default n
1629 depends on m
1630 help
1631 This builds the "test_user_copy" module that runs sanity checks
1632 on the copy_to/from_user infrastructure, making sure basic
1633 user/kernel boundary testing is working. If it fails to load,
1634 a regression has been detected in the user/kernel memory boundary
1635 protections.
1637 If unsure, say N.
1639 config TEST_BPF
1640 tristate "Test BPF filter functionality"
1641 default n
1642 depends on m && NET
1643 help
1644 This builds the "test_bpf" module that runs various test vectors
1645 against the BPF interpreter or BPF JIT compiler depending on the
1646 current setting. This is in particular useful for BPF JIT compiler
1647 development, but also to run regression tests against changes in
1648 the interpreter code.
1650 If unsure, say N.
1652 source "samples/Kconfig"
1654 source "lib/Kconfig.kgdb"