| blob | 07c28323f88fe99d08900d82e3eacec6ca88fb91 |
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 MESSAGE_LOGLEVEL_DEFAULT
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 DEBUG_INFO_SPLIT
147 bool "Produce split debuginfo in .dwo files"
148 depends on DEBUG_INFO
149 help
150 Generate debug info into separate .dwo files. This significantly
151 reduces the build directory size for builds with DEBUG_INFO,
152 because it stores the information only once on disk in .dwo
153 files instead of multiple times in object files and executables.
154 In addition the debug information is also compressed.
156 Requires recent gcc (4.7+) and recent gdb/binutils.
157 Any tool that packages or reads debug information would need
158 to know about the .dwo files and include them.
159 Incompatible with older versions of ccache.
161 config DEBUG_INFO_DWARF4
162 bool "Generate dwarf4 debuginfo"
163 depends on DEBUG_INFO
164 help
165 Generate dwarf4 debug info. This requires recent versions
166 of gcc and gdb. It makes the debug information larger.
167 But it significantly improves the success of resolving
168 variables in gdb on optimized code.
170 config ENABLE_WARN_DEPRECATED
171 bool "Enable __deprecated logic"
172 default y
173 help
174 Enable the __deprecated logic in the kernel build.
175 Disable this to suppress the "warning: 'foo' is deprecated
176 (declared at kernel/power/somefile.c:1234)" messages.
178 config ENABLE_MUST_CHECK
179 bool "Enable __must_check logic"
180 default y
181 help
182 Enable the __must_check logic in the kernel build. Disable this to
183 suppress the "warning: ignoring return value of 'foo', declared with
184 attribute warn_unused_result" messages.
186 config FRAME_WARN
187 int "Warn for stack frames larger than (needs gcc 4.4)"
188 range 0 8192
189 default 1024 if !64BIT
190 default 2048 if 64BIT
191 help
192 Tell gcc to warn at build time for stack frames larger than this.
193 Setting this too low will cause a lot of warnings.
194 Setting it to 0 disables the warning.
195 Requires gcc 4.4
197 config STRIP_ASM_SYMS
198 bool "Strip assembler-generated symbols during link"
199 default n
200 help
201 Strip internal assembler-generated symbols during a link (symbols
202 that look like '.Lxxx') so they don't pollute the output of
203 get_wchan() and suchlike.
205 config READABLE_ASM
206 bool "Generate readable assembler code"
207 depends on DEBUG_KERNEL
208 help
209 Disable some compiler optimizations that tend to generate human unreadable
210 assembler output. This may make the kernel slightly slower, but it helps
211 to keep kernel developers who have to stare a lot at assembler listings
212 sane.
214 config UNUSED_SYMBOLS
215 bool "Enable unused/obsolete exported symbols"
216 default y if X86
217 help
218 Unused but exported symbols make the kernel needlessly bigger. For
219 that reason most of these unused exports will soon be removed. This
220 option is provided temporarily to provide a transition period in case
221 some external kernel module needs one of these symbols anyway. If you
222 encounter such a case in your module, consider if you are actually
223 using the right API. (rationale: since nobody in the kernel is using
224 this in a module, there is a pretty good chance it's actually the
225 wrong interface to use). If you really need the symbol, please send a
226 mail to the linux kernel mailing list mentioning the symbol and why
227 you really need it, and what the merge plan to the mainline kernel for
228 your module is.
230 config DEBUG_FS
231 bool "Debug Filesystem"
232 help
233 debugfs is a virtual file system that kernel developers use to put
234 debugging files into. Enable this option to be able to read and
235 write to these files.
237 For detailed documentation on the debugfs API, see
238 Documentation/DocBook/filesystems.
240 If unsure, say N.
242 config HEADERS_CHECK
243 bool "Run 'make headers_check' when building vmlinux"
244 depends on !UML
245 help
246 This option will extract the user-visible kernel headers whenever
247 building the kernel, and will run basic sanity checks on them to
248 ensure that exported files do not attempt to include files which
249 were not exported, etc.
251 If you're making modifications to header files which are
252 relevant for userspace, say 'Y', and check the headers
253 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
254 your build tree), to make sure they're suitable.
256 config DEBUG_SECTION_MISMATCH
257 bool "Enable full Section mismatch analysis"
258 help
259 The section mismatch analysis checks if there are illegal
260 references from one section to another section.
261 During linktime or runtime, some sections are dropped;
262 any use of code/data previously in these sections would
263 most likely result in an oops.
264 In the code, functions and variables are annotated with
265 __init,, etc. (see the full list in include/linux/init.h),
266 which results in the code/data being placed in specific sections.
267 The section mismatch analysis is always performed after a full
268 kernel build, and enabling this option causes the following
269 additional steps to occur:
270 - Add the option -fno-inline-functions-called-once to gcc commands.
271 When inlining a function annotated with __init in a non-init
272 function, we would lose the section information and thus
273 the analysis would not catch the illegal reference.
274 This option tells gcc to inline less (but it does result in
275 a larger kernel).
276 - Run the section mismatch analysis for each module/built-in.o file.
277 When we run the section mismatch analysis on vmlinux.o, we
278 lose valueble information about where the mismatch was
279 introduced.
280 Running the analysis for each module/built-in.o file
281 tells where the mismatch happens much closer to the
282 source. The drawback is that the same mismatch is
283 reported at least twice.
284 - Enable verbose reporting from modpost in order to help resolve
285 the section mismatches that are reported.
287 #
288 # Select this config option from the architecture Kconfig, if it
289 # is preferred to always offer frame pointers as a config
290 # option on the architecture (regardless of KERNEL_DEBUG):
291 #
292 config ARCH_WANT_FRAME_POINTERS
293 bool
294 help
296 config FRAME_POINTER
297 bool "Compile the kernel with frame pointers"
298 depends on DEBUG_KERNEL && \
299 (CRIS || M68K || FRV || UML || \
300 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
301 ARCH_WANT_FRAME_POINTERS
302 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
303 help
304 If you say Y here the resulting kernel image will be slightly
305 larger and slower, but it gives very useful debugging information
306 in case of kernel bugs. (precise oopses/stacktraces/warnings)
308 config DEBUG_FORCE_WEAK_PER_CPU
309 bool "Force weak per-cpu definitions"
310 depends on DEBUG_KERNEL
311 help
312 s390 and alpha require percpu variables in modules to be
313 defined weak to work around addressing range issue which
314 puts the following two restrictions on percpu variable
315 definitions.
317 1. percpu symbols must be unique whether static or not
318 2. percpu variables can't be defined inside a function
320 To ensure that generic code follows the above rules, this
321 option forces all percpu variables to be defined as weak.
323 endmenu # "Compiler options"
325 config MAGIC_SYSRQ
326 bool "Magic SysRq key"
327 depends on !UML
328 help
329 If you say Y here, you will have some control over the system even
330 if the system crashes for example during kernel debugging (e.g., you
331 will be able to flush the buffer cache to disk, reboot the system
332 immediately or dump some status information). This is accomplished
333 by pressing various keys while holding SysRq (Alt+PrintScreen). It
334 also works on a serial console (on PC hardware at least), if you
335 send a BREAK and then within 5 seconds a command keypress. The
336 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
337 unless you really know what this hack does.
339 config MAGIC_SYSRQ_DEFAULT_ENABLE
340 hex "Enable magic SysRq key functions by default"
341 depends on MAGIC_SYSRQ
342 default 0x1
343 help
344 Specifies which SysRq key functions are enabled by default.
345 This may be set to 1 or 0 to enable or disable them all, or
346 to a bitmask as described in Documentation/sysrq.txt.
348 config DEBUG_KERNEL
349 bool "Kernel debugging"
350 help
351 Say Y here if you are developing drivers or trying to debug and
352 identify kernel problems.
354 menu "Memory Debugging"
356 source mm/Kconfig.debug
358 config DEBUG_OBJECTS
359 bool "Debug object operations"
360 depends on DEBUG_KERNEL
361 help
362 If you say Y here, additional code will be inserted into the
363 kernel to track the life time of various objects and validate
364 the operations on those objects.
366 config DEBUG_OBJECTS_SELFTEST
367 bool "Debug objects selftest"
368 depends on DEBUG_OBJECTS
369 help
370 This enables the selftest of the object debug code.
372 config DEBUG_OBJECTS_FREE
373 bool "Debug objects in freed memory"
374 depends on DEBUG_OBJECTS
375 help
376 This enables checks whether a k/v free operation frees an area
377 which contains an object which has not been deactivated
378 properly. This can make kmalloc/kfree-intensive workloads
379 much slower.
381 config DEBUG_OBJECTS_TIMERS
382 bool "Debug timer objects"
383 depends on DEBUG_OBJECTS
384 help
385 If you say Y here, additional code will be inserted into the
386 timer routines to track the life time of timer objects and
387 validate the timer operations.
389 config DEBUG_OBJECTS_WORK
390 bool "Debug work objects"
391 depends on DEBUG_OBJECTS
392 help
393 If you say Y here, additional code will be inserted into the
394 work queue routines to track the life time of work objects and
395 validate the work operations.
397 config DEBUG_OBJECTS_RCU_HEAD
398 bool "Debug RCU callbacks objects"
399 depends on DEBUG_OBJECTS
400 help
401 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
403 config DEBUG_OBJECTS_PERCPU_COUNTER
404 bool "Debug percpu counter objects"
405 depends on DEBUG_OBJECTS
406 help
407 If you say Y here, additional code will be inserted into the
408 percpu counter routines to track the life time of percpu counter
409 objects and validate the percpu counter operations.
411 config DEBUG_OBJECTS_ENABLE_DEFAULT
412 int "debug_objects bootup default value (0-1)"
413 range 0 1
414 default "1"
415 depends on DEBUG_OBJECTS
416 help
417 Debug objects boot parameter default value
419 config DEBUG_SLAB
420 bool "Debug slab memory allocations"
421 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
422 help
423 Say Y here to have the kernel do limited verification on memory
424 allocation as well as poisoning memory on free to catch use of freed
425 memory. This can make kmalloc/kfree-intensive workloads much slower.
427 config DEBUG_SLAB_LEAK
428 bool "Memory leak debugging"
429 depends on DEBUG_SLAB
431 config SLUB_DEBUG_ON
432 bool "SLUB debugging on by default"
433 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
434 default n
435 help
436 Boot with debugging on by default. SLUB boots by default with
437 the runtime debug capabilities switched off. Enabling this is
438 equivalent to specifying the "slub_debug" parameter on boot.
439 There is no support for more fine grained debug control like
440 possible with slub_debug=xxx. SLUB debugging may be switched
441 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
442 "slub_debug=-".
444 config SLUB_STATS
445 default n
446 bool "Enable SLUB performance statistics"
447 depends on SLUB && SYSFS
448 help
449 SLUB statistics are useful to debug SLUBs allocation behavior in
450 order find ways to optimize the allocator. This should never be
451 enabled for production use since keeping statistics slows down
452 the allocator by a few percentage points. The slabinfo command
453 supports the determination of the most active slabs to figure
454 out which slabs are relevant to a particular load.
455 Try running: slabinfo -DA
457 config HAVE_DEBUG_KMEMLEAK
458 bool
460 config DEBUG_KMEMLEAK
461 bool "Kernel memory leak detector"
462 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
463 select DEBUG_FS
464 select STACKTRACE if STACKTRACE_SUPPORT
465 select KALLSYMS
466 select CRC32
467 help
468 Say Y here if you want to enable the memory leak
469 detector. The memory allocation/freeing is traced in a way
470 similar to the Boehm's conservative garbage collector, the
471 difference being that the orphan objects are not freed but
472 only shown in /sys/kernel/debug/kmemleak. Enabling this
473 feature will introduce an overhead to memory
474 allocations. See Documentation/kmemleak.txt for more
475 details.
477 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
478 of finding leaks due to the slab objects poisoning.
480 In order to access the kmemleak file, debugfs needs to be
481 mounted (usually at /sys/kernel/debug).
483 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
484 int "Maximum kmemleak early log entries"
485 depends on DEBUG_KMEMLEAK
486 range 200 40000
487 default 400
488 help
489 Kmemleak must track all the memory allocations to avoid
490 reporting false positives. Since memory may be allocated or
491 freed before kmemleak is initialised, an early log buffer is
492 used to store these actions. If kmemleak reports "early log
493 buffer exceeded", please increase this value.
495 config DEBUG_KMEMLEAK_TEST
496 tristate "Simple test for the kernel memory leak detector"
497 depends on DEBUG_KMEMLEAK && m
498 help
499 This option enables a module that explicitly leaks memory.
501 If unsure, say N.
503 config DEBUG_KMEMLEAK_DEFAULT_OFF
504 bool "Default kmemleak to off"
505 depends on DEBUG_KMEMLEAK
506 help
507 Say Y here to disable kmemleak by default. It can then be enabled
508 on the command line via kmemleak=on.
510 config DEBUG_STACK_USAGE
511 bool "Stack utilization instrumentation"
512 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
513 help
514 Enables the display of the minimum amount of free stack which each
515 task has ever had available in the sysrq-T and sysrq-P debug output.
517 This option will slow down process creation somewhat.
519 config DEBUG_VM
520 bool "Debug VM"
521 depends on DEBUG_KERNEL
522 help
523 Enable this to turn on extended checks in the virtual-memory system
524 that may impact performance.
526 If unsure, say N.
528 config DEBUG_VM_VMACACHE
529 bool "Debug VMA caching"
530 depends on DEBUG_VM
531 help
532 Enable this to turn on VMA caching debug information. Doing so
533 can cause significant overhead, so only enable it in non-production
534 environments.
536 If unsure, say N.
538 config DEBUG_VM_RB
539 bool "Debug VM red-black trees"
540 depends on DEBUG_VM
541 help
542 Enable VM red-black tree debugging information and extra validations.
544 If unsure, say N.
546 config DEBUG_VIRTUAL
547 bool "Debug VM translations"
548 depends on DEBUG_KERNEL && X86
549 help
550 Enable some costly sanity checks in virtual to page code. This can
551 catch mistakes with virt_to_page() and friends.
553 If unsure, say N.
555 config DEBUG_NOMMU_REGIONS
556 bool "Debug the global anon/private NOMMU mapping region tree"
557 depends on DEBUG_KERNEL && !MMU
558 help
559 This option causes the global tree of anonymous and private mapping
560 regions to be regularly checked for invalid topology.
562 config DEBUG_MEMORY_INIT
563 bool "Debug memory initialisation" if EXPERT
564 default !EXPERT
565 help
566 Enable this for additional checks during memory initialisation.
567 The sanity checks verify aspects of the VM such as the memory model
568 and other information provided by the architecture. Verbose
569 information will be printed at KERN_DEBUG loglevel depending
570 on the mminit_loglevel= command-line option.
572 If unsure, say Y
574 config MEMORY_NOTIFIER_ERROR_INJECT
575 tristate "Memory hotplug notifier error injection module"
576 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
577 help
578 This option provides the ability to inject artificial errors to
579 memory hotplug notifier chain callbacks. It is controlled through
580 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
582 If the notifier call chain should be failed with some events
583 notified, write the error code to "actions/<notifier event>/error".
585 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
587 # cd /sys/kernel/debug/notifier-error-inject/memory
588 # echo -12 > actions/MEM_GOING_OFFLINE/error
589 # echo offline > /sys/devices/system/memory/memoryXXX/state
590 bash: echo: write error: Cannot allocate memory
592 To compile this code as a module, choose M here: the module will
593 be called memory-notifier-error-inject.
595 If unsure, say N.
597 config DEBUG_PER_CPU_MAPS
598 bool "Debug access to per_cpu maps"
599 depends on DEBUG_KERNEL
600 depends on SMP
601 help
602 Say Y to verify that the per_cpu map being accessed has
603 been set up. This adds a fair amount of code to kernel memory
604 and decreases performance.
606 Say N if unsure.
608 config DEBUG_HIGHMEM
609 bool "Highmem debugging"
610 depends on DEBUG_KERNEL && HIGHMEM
611 help
612 This option enables additional error checking for high memory
613 systems. Disable for production systems.
615 config HAVE_DEBUG_STACKOVERFLOW
616 bool
618 config DEBUG_STACKOVERFLOW
619 bool "Check for stack overflows"
620 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
621 ---help---
622 Say Y here if you want to check for overflows of kernel, IRQ
623 and exception stacks (if your archicture uses them). This
624 option will show detailed messages if free stack space drops
625 below a certain limit.
627 These kinds of bugs usually occur when call-chains in the
628 kernel get too deep, especially when interrupts are
629 involved.
631 Use this in cases where you see apparently random memory
632 corruption, especially if it appears in 'struct thread_info'
634 If in doubt, say "N".
636 source "lib/Kconfig.kmemcheck"
638 endmenu # "Memory Debugging"
640 config DEBUG_SHIRQ
641 bool "Debug shared IRQ handlers"
642 depends on DEBUG_KERNEL
643 help
644 Enable this to generate a spurious interrupt as soon as a shared
645 interrupt handler is registered, and just before one is deregistered.
646 Drivers ought to be able to handle interrupts coming in at those
647 points; some don't and need to be caught.
649 menu "Debug Lockups and Hangs"
651 config LOCKUP_DETECTOR
652 bool "Detect Hard and Soft Lockups"
653 depends on DEBUG_KERNEL && !S390
654 help
655 Say Y here to enable the kernel to act as a watchdog to detect
656 hard and soft lockups.
658 Softlockups are bugs that cause the kernel to loop in kernel
659 mode for more than 20 seconds, without giving other tasks a
660 chance to run. The current stack trace is displayed upon
661 detection and the system will stay locked up.
663 Hardlockups are bugs that cause the CPU to loop in kernel mode
664 for more than 10 seconds, without letting other interrupts have a
665 chance to run. The current stack trace is displayed upon detection
666 and the system will stay locked up.
668 The overhead should be minimal. A periodic hrtimer runs to
669 generate interrupts and kick the watchdog task every 4 seconds.
670 An NMI is generated every 10 seconds or so to check for hardlockups.
672 The frequency of hrtimer and NMI events and the soft and hard lockup
673 thresholds can be controlled through the sysctl watchdog_thresh.
675 config HARDLOCKUP_DETECTOR
676 def_bool y
677 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
678 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
680 config BOOTPARAM_HARDLOCKUP_PANIC
681 bool "Panic (Reboot) On Hard Lockups"
682 depends on HARDLOCKUP_DETECTOR
683 help
684 Say Y here to enable the kernel to panic on "hard lockups",
685 which are bugs that cause the kernel to loop in kernel
686 mode with interrupts disabled for more than 10 seconds (configurable
687 using the watchdog_thresh sysctl).
689 Say N if unsure.
691 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
692 int
693 depends on HARDLOCKUP_DETECTOR
694 range 0 1
695 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
696 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
698 config BOOTPARAM_SOFTLOCKUP_PANIC
699 bool "Panic (Reboot) On Soft Lockups"
700 depends on LOCKUP_DETECTOR
701 help
702 Say Y here to enable the kernel to panic on "soft lockups",
703 which are bugs that cause the kernel to loop in kernel
704 mode for more than 20 seconds (configurable using the watchdog_thresh
705 sysctl), without giving other tasks a chance to run.
707 The panic can be used in combination with panic_timeout,
708 to cause the system to reboot automatically after a
709 lockup has been detected. This feature is useful for
710 high-availability systems that have uptime guarantees and
711 where a lockup must be resolved ASAP.
713 Say N if unsure.
715 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
716 int
717 depends on LOCKUP_DETECTOR
718 range 0 1
719 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
720 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
722 config DETECT_HUNG_TASK
723 bool "Detect Hung Tasks"
724 depends on DEBUG_KERNEL
725 default LOCKUP_DETECTOR
726 help
727 Say Y here to enable the kernel to detect "hung tasks",
728 which are bugs that cause the task to be stuck in
729 uninterruptible "D" state indefinitiley.
731 When a hung task is detected, the kernel will print the
732 current stack trace (which you should report), but the
733 task will stay in uninterruptible state. If lockdep is
734 enabled then all held locks will also be reported. This
735 feature has negligible overhead.
737 config DEFAULT_HUNG_TASK_TIMEOUT
738 int "Default timeout for hung task detection (in seconds)"
739 depends on DETECT_HUNG_TASK
740 default 120
741 help
742 This option controls the default timeout (in seconds) used
743 to determine when a task has become non-responsive and should
744 be considered hung.
746 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
747 sysctl or by writing a value to
748 /proc/sys/kernel/hung_task_timeout_secs.
750 A timeout of 0 disables the check. The default is two minutes.
751 Keeping the default should be fine in most cases.
753 config BOOTPARAM_HUNG_TASK_PANIC
754 bool "Panic (Reboot) On Hung Tasks"
755 depends on DETECT_HUNG_TASK
756 help
757 Say Y here to enable the kernel to panic on "hung tasks",
758 which are bugs that cause the kernel to leave a task stuck
759 in uninterruptible "D" state.
761 The panic can be used in combination with panic_timeout,
762 to cause the system to reboot automatically after a
763 hung task has been detected. This feature is useful for
764 high-availability systems that have uptime guarantees and
765 where a hung tasks must be resolved ASAP.
767 Say N if unsure.
769 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
770 int
771 depends on DETECT_HUNG_TASK
772 range 0 1
773 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
774 default 1 if BOOTPARAM_HUNG_TASK_PANIC
776 endmenu # "Debug lockups and hangs"
778 config PANIC_ON_OOPS
779 bool "Panic on Oops"
780 help
781 Say Y here to enable the kernel to panic when it oopses. This
782 has the same effect as setting oops=panic on the kernel command
783 line.
785 This feature is useful to ensure that the kernel does not do
786 anything erroneous after an oops which could result in data
787 corruption or other issues.
789 Say N if unsure.
791 config PANIC_ON_OOPS_VALUE
792 int
793 range 0 1
794 default 0 if !PANIC_ON_OOPS
795 default 1 if PANIC_ON_OOPS
797 config PANIC_TIMEOUT
798 int "panic timeout"
799 default 0
800 help
801 Set the timeout value (in seconds) until a reboot occurs when the
802 the kernel panics. If n = 0, then we wait forever. A timeout
803 value n > 0 will wait n seconds before rebooting, while a timeout
804 value n < 0 will reboot immediately.
806 config SCHED_DEBUG
807 bool "Collect scheduler debugging info"
808 depends on DEBUG_KERNEL && PROC_FS
809 default y
810 help
811 If you say Y here, the /proc/sched_debug file will be provided
812 that can help debug the scheduler. The runtime overhead of this
813 option is minimal.
815 config SCHEDSTATS
816 bool "Collect scheduler statistics"
817 depends on DEBUG_KERNEL && PROC_FS
818 help
819 If you say Y here, additional code will be inserted into the
820 scheduler and related routines to collect statistics about
821 scheduler behavior and provide them in /proc/schedstat. These
822 stats may be useful for both tuning and debugging the scheduler
823 If you aren't debugging the scheduler or trying to tune a specific
824 application, you can say N to avoid the very slight overhead
825 this adds.
827 config TIMER_STATS
828 bool "Collect kernel timers statistics"
829 depends on DEBUG_KERNEL && PROC_FS
830 help
831 If you say Y here, additional code will be inserted into the
832 timer routines to collect statistics about kernel timers being
833 reprogrammed. The statistics can be read from /proc/timer_stats.
834 The statistics collection is started by writing 1 to /proc/timer_stats,
835 writing 0 stops it. This feature is useful to collect information
836 about timer usage patterns in kernel and userspace. This feature
837 is lightweight if enabled in the kernel config but not activated
838 (it defaults to deactivated on bootup and will only be activated
839 if some application like powertop activates it explicitly).
841 config DEBUG_PREEMPT
842 bool "Debug preemptible kernel"
843 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
844 default y
845 help
846 If you say Y here then the kernel will use a debug variant of the
847 commonly used smp_processor_id() function and will print warnings
848 if kernel code uses it in a preemption-unsafe way. Also, the kernel
849 will detect preemption count underflows.
851 menu "Lock Debugging (spinlocks, mutexes, etc...)"
853 config DEBUG_RT_MUTEXES
854 bool "RT Mutex debugging, deadlock detection"
855 depends on DEBUG_KERNEL && RT_MUTEXES
856 help
857 This allows rt mutex semantics violations and rt mutex related
858 deadlocks (lockups) to be detected and reported automatically.
860 config RT_MUTEX_TESTER
861 bool "Built-in scriptable tester for rt-mutexes"
862 depends on DEBUG_KERNEL && RT_MUTEXES && BROKEN
863 help
864 This option enables a rt-mutex tester.
866 config DEBUG_SPINLOCK
867 bool "Spinlock and rw-lock debugging: basic checks"
868 depends on DEBUG_KERNEL
869 select UNINLINE_SPIN_UNLOCK
870 help
871 Say Y here and build SMP to catch missing spinlock initialization
872 and certain other kinds of spinlock errors commonly made. This is
873 best used in conjunction with the NMI watchdog so that spinlock
874 deadlocks are also debuggable.
876 config DEBUG_MUTEXES
877 bool "Mutex debugging: basic checks"
878 depends on DEBUG_KERNEL
879 help
880 This feature allows mutex semantics violations to be detected and
881 reported.
883 config DEBUG_WW_MUTEX_SLOWPATH
884 bool "Wait/wound mutex debugging: Slowpath testing"
885 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
886 select DEBUG_LOCK_ALLOC
887 select DEBUG_SPINLOCK
888 select DEBUG_MUTEXES
889 help
890 This feature enables slowpath testing for w/w mutex users by
891 injecting additional -EDEADLK wound/backoff cases. Together with
892 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
893 will test all possible w/w mutex interface abuse with the
894 exception of simply not acquiring all the required locks.
896 config DEBUG_LOCK_ALLOC
897 bool "Lock debugging: detect incorrect freeing of live locks"
898 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
899 select DEBUG_SPINLOCK
900 select DEBUG_MUTEXES
901 select LOCKDEP
902 help
903 This feature will check whether any held lock (spinlock, rwlock,
904 mutex or rwsem) is incorrectly freed by the kernel, via any of the
905 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
906 vfree(), etc.), whether a live lock is incorrectly reinitialized via
907 spin_lock_init()/mutex_init()/etc., or whether there is any lock
908 held during task exit.
910 config PROVE_LOCKING
911 bool "Lock debugging: prove locking correctness"
912 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
913 select LOCKDEP
914 select DEBUG_SPINLOCK
915 select DEBUG_MUTEXES
916 select DEBUG_LOCK_ALLOC
917 select TRACE_IRQFLAGS
918 default n
919 help
920 This feature enables the kernel to prove that all locking
921 that occurs in the kernel runtime is mathematically
922 correct: that under no circumstance could an arbitrary (and
923 not yet triggered) combination of observed locking
924 sequences (on an arbitrary number of CPUs, running an
925 arbitrary number of tasks and interrupt contexts) cause a
926 deadlock.
928 In short, this feature enables the kernel to report locking
929 related deadlocks before they actually occur.
931 The proof does not depend on how hard and complex a
932 deadlock scenario would be to trigger: how many
933 participant CPUs, tasks and irq-contexts would be needed
934 for it to trigger. The proof also does not depend on
935 timing: if a race and a resulting deadlock is possible
936 theoretically (no matter how unlikely the race scenario
937 is), it will be proven so and will immediately be
938 reported by the kernel (once the event is observed that
939 makes the deadlock theoretically possible).
941 If a deadlock is impossible (i.e. the locking rules, as
942 observed by the kernel, are mathematically correct), the
943 kernel reports nothing.
945 NOTE: this feature can also be enabled for rwlocks, mutexes
946 and rwsems - in which case all dependencies between these
947 different locking variants are observed and mapped too, and
948 the proof of observed correctness is also maintained for an
949 arbitrary combination of these separate locking variants.
951 For more details, see Documentation/lockdep-design.txt.
953 config LOCKDEP
954 bool
955 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
956 select STACKTRACE
957 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
958 select KALLSYMS
959 select KALLSYMS_ALL
961 config LOCK_STAT
962 bool "Lock usage statistics"
963 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
964 select LOCKDEP
965 select DEBUG_SPINLOCK
966 select DEBUG_MUTEXES
967 select DEBUG_LOCK_ALLOC
968 default n
969 help
970 This feature enables tracking lock contention points
972 For more details, see Documentation/lockstat.txt
974 This also enables lock events required by "perf lock",
975 subcommand of perf.
976 If you want to use "perf lock", you also need to turn on
977 CONFIG_EVENT_TRACING.
979 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
980 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
982 config DEBUG_LOCKDEP
983 bool "Lock dependency engine debugging"
984 depends on DEBUG_KERNEL && LOCKDEP
985 help
986 If you say Y here, the lock dependency engine will do
987 additional runtime checks to debug itself, at the price
988 of more runtime overhead.
990 config DEBUG_ATOMIC_SLEEP
991 bool "Sleep inside atomic section checking"
992 select PREEMPT_COUNT
993 depends on DEBUG_KERNEL
994 help
995 If you say Y here, various routines which may sleep will become very
996 noisy if they are called inside atomic sections: when a spinlock is
997 held, inside an rcu read side critical section, inside preempt disabled
998 sections, inside an interrupt, etc...
1000 config DEBUG_LOCKING_API_SELFTESTS
1001 bool "Locking API boot-time self-tests"
1002 depends on DEBUG_KERNEL
1003 help
1004 Say Y here if you want the kernel to run a short self-test during
1005 bootup. The self-test checks whether common types of locking bugs
1006 are detected by debugging mechanisms or not. (if you disable
1007 lock debugging then those bugs wont be detected of course.)
1008 The following locking APIs are covered: spinlocks, rwlocks,
1009 mutexes and rwsems.
1011 config LOCK_TORTURE_TEST
1012 tristate "torture tests for locking"
1013 depends on DEBUG_KERNEL
1014 select TORTURE_TEST
1015 default n
1016 help
1017 This option provides a kernel module that runs torture tests
1018 on kernel locking primitives. The kernel module may be built
1019 after the fact on the running kernel to be tested, if desired.
1021 Say Y here if you want kernel locking-primitive torture tests
1022 to be built into the kernel.
1023 Say M if you want these torture tests to build as a module.
1024 Say N if you are unsure.
1026 endmenu # lock debugging
1028 config TRACE_IRQFLAGS
1029 bool
1030 help
1031 Enables hooks to interrupt enabling and disabling for
1032 either tracing or lock debugging.
1034 config STACKTRACE
1035 bool
1036 depends on STACKTRACE_SUPPORT
1038 config DEBUG_KOBJECT
1039 bool "kobject debugging"
1040 depends on DEBUG_KERNEL
1041 help
1042 If you say Y here, some extra kobject debugging messages will be sent
1043 to the syslog.
1045 config DEBUG_KOBJECT_RELEASE
1046 bool "kobject release debugging"
1047 depends on DEBUG_OBJECTS_TIMERS
1048 help
1049 kobjects are reference counted objects. This means that their
1050 last reference count put is not predictable, and the kobject can
1051 live on past the point at which a driver decides to drop it's
1052 initial reference to the kobject gained on allocation. An
1053 example of this would be a struct device which has just been
1054 unregistered.
1056 However, some buggy drivers assume that after such an operation,
1057 the memory backing the kobject can be immediately freed. This
1058 goes completely against the principles of a refcounted object.
1060 If you say Y here, the kernel will delay the release of kobjects
1061 on the last reference count to improve the visibility of this
1062 kind of kobject release bug.
1064 config HAVE_DEBUG_BUGVERBOSE
1065 bool
1067 config DEBUG_BUGVERBOSE
1068 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1069 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1070 default y
1071 help
1072 Say Y here to make BUG() panics output the file name and line number
1073 of the BUG call as well as the EIP and oops trace. This aids
1074 debugging but costs about 70-100K of memory.
1076 config DEBUG_LIST
1077 bool "Debug linked list manipulation"
1078 depends on DEBUG_KERNEL
1079 help
1080 Enable this to turn on extended checks in the linked-list
1081 walking routines.
1083 If unsure, say N.
1085 config DEBUG_PI_LIST
1086 bool "Debug priority linked list manipulation"
1087 depends on DEBUG_KERNEL
1088 help
1089 Enable this to turn on extended checks in the priority-ordered
1090 linked-list (plist) walking routines. This checks the entire
1091 list multiple times during each manipulation.
1093 If unsure, say N.
1095 config DEBUG_SG
1096 bool "Debug SG table operations"
1097 depends on DEBUG_KERNEL
1098 help
1099 Enable this to turn on checks on scatter-gather tables. This can
1100 help find problems with drivers that do not properly initialize
1101 their sg tables.
1103 If unsure, say N.
1105 config DEBUG_NOTIFIERS
1106 bool "Debug notifier call chains"
1107 depends on DEBUG_KERNEL
1108 help
1109 Enable this to turn on sanity checking for notifier call chains.
1110 This is most useful for kernel developers to make sure that
1111 modules properly unregister themselves from notifier chains.
1112 This is a relatively cheap check but if you care about maximum
1113 performance, say N.
1115 config DEBUG_CREDENTIALS
1116 bool "Debug credential management"
1117 depends on DEBUG_KERNEL
1118 help
1119 Enable this to turn on some debug checking for credential
1120 management. The additional code keeps track of the number of
1121 pointers from task_structs to any given cred struct, and checks to
1122 see that this number never exceeds the usage count of the cred
1123 struct.
1125 Furthermore, if SELinux is enabled, this also checks that the
1126 security pointer in the cred struct is never seen to be invalid.
1128 If unsure, say N.
1130 menu "RCU Debugging"
1132 config PROVE_RCU
1133 bool "RCU debugging: prove RCU correctness"
1134 depends on PROVE_LOCKING
1135 default n
1136 help
1137 This feature enables lockdep extensions that check for correct
1138 use of RCU APIs. This is currently under development. Say Y
1139 if you want to debug RCU usage or help work on the PROVE_RCU
1140 feature.
1142 Say N if you are unsure.
1144 config PROVE_RCU_REPEATEDLY
1145 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1146 depends on PROVE_RCU
1147 default n
1148 help
1149 By itself, PROVE_RCU will disable checking upon issuing the
1150 first warning (or "splat"). This feature prevents such
1151 disabling, allowing multiple RCU-lockdep warnings to be printed
1152 on a single reboot.
1154 Say Y to allow multiple RCU-lockdep warnings per boot.
1156 Say N if you are unsure.
1158 config SPARSE_RCU_POINTER
1159 bool "RCU debugging: sparse-based checks for pointer usage"
1160 default n
1161 help
1162 This feature enables the __rcu sparse annotation for
1163 RCU-protected pointers. This annotation will cause sparse
1164 to flag any non-RCU used of annotated pointers. This can be
1165 helpful when debugging RCU usage. Please note that this feature
1166 is not intended to enforce code cleanliness; it is instead merely
1167 a debugging aid.
1169 Say Y to make sparse flag questionable use of RCU-protected pointers
1171 Say N if you are unsure.
1173 config TORTURE_TEST
1174 tristate
1175 default n
1177 config RCU_TORTURE_TEST
1178 tristate "torture tests for RCU"
1179 depends on DEBUG_KERNEL
1180 select TORTURE_TEST
1181 default n
1182 help
1183 This option provides a kernel module that runs torture tests
1184 on the RCU infrastructure. The kernel module may be built
1185 after the fact on the running kernel to be tested, if desired.
1187 Say Y here if you want RCU torture tests to be built into
1188 the kernel.
1189 Say M if you want the RCU torture tests to build as a module.
1190 Say N if you are unsure.
1192 config RCU_TORTURE_TEST_RUNNABLE
1193 bool "torture tests for RCU runnable by default"
1194 depends on RCU_TORTURE_TEST = y
1195 default n
1196 help
1197 This option provides a way to build the RCU torture tests
1198 directly into the kernel without them starting up at boot
1199 time. You can use /proc/sys/kernel/rcutorture_runnable
1200 to manually override this setting. This /proc file is
1201 available only when the RCU torture tests have been built
1202 into the kernel.
1204 Say Y here if you want the RCU torture tests to start during
1205 boot (you probably don't).
1206 Say N here if you want the RCU torture tests to start only
1207 after being manually enabled via /proc.
1209 config RCU_CPU_STALL_TIMEOUT
1210 int "RCU CPU stall timeout in seconds"
1211 depends on RCU_STALL_COMMON
1212 range 3 300
1213 default 21
1214 help
1215 If a given RCU grace period extends more than the specified
1216 number of seconds, a CPU stall warning is printed. If the
1217 RCU grace period persists, additional CPU stall warnings are
1218 printed at more widely spaced intervals.
1220 config RCU_CPU_STALL_VERBOSE
1221 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
1222 depends on TREE_PREEMPT_RCU
1223 default y
1224 help
1225 This option causes RCU to printk detailed per-task information
1226 for any tasks that are stalling the current RCU grace period.
1228 Say N if you are unsure.
1230 Say Y if you want to enable such checks.
1232 config RCU_CPU_STALL_INFO
1233 bool "Print additional diagnostics on RCU CPU stall"
1234 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1235 default n
1236 help
1237 For each stalled CPU that is aware of the current RCU grace
1238 period, print out additional per-CPU diagnostic information
1239 regarding scheduling-clock ticks, idle state, and,
1240 for RCU_FAST_NO_HZ kernels, idle-entry state.
1242 Say N if you are unsure.
1244 Say Y if you want to enable such diagnostics.
1246 config RCU_TRACE
1247 bool "Enable tracing for RCU"
1248 depends on DEBUG_KERNEL
1249 select TRACE_CLOCK
1250 help
1251 This option provides tracing in RCU which presents stats
1252 in debugfs for debugging RCU implementation.
1254 Say Y here if you want to enable RCU tracing
1255 Say N if you are unsure.
1257 endmenu # "RCU Debugging"
1259 config DEBUG_BLOCK_EXT_DEVT
1260 bool "Force extended block device numbers and spread them"
1261 depends on DEBUG_KERNEL
1262 depends on BLOCK
1263 default n
1264 help
1265 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1266 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1267 YOU ARE DOING. Distros, please enable this and fix whatever
1268 is broken.
1270 Conventionally, block device numbers are allocated from
1271 predetermined contiguous area. However, extended block area
1272 may introduce non-contiguous block device numbers. This
1273 option forces most block device numbers to be allocated from
1274 the extended space and spreads them to discover kernel or
1275 userland code paths which assume predetermined contiguous
1276 device number allocation.
1278 Note that turning on this debug option shuffles all the
1279 device numbers for all IDE and SCSI devices including libata
1280 ones, so root partition specified using device number
1281 directly (via rdev or root=MAJ:MIN) won't work anymore.
1282 Textual device names (root=/dev/sdXn) will continue to work.
1284 Say N if you are unsure.
1286 config NOTIFIER_ERROR_INJECTION
1287 tristate "Notifier error injection"
1288 depends on DEBUG_KERNEL
1289 select DEBUG_FS
1290 help
1291 This option provides the ability to inject artificial errors to
1292 specified notifier chain callbacks. It is useful to test the error
1293 handling of notifier call chain failures.
1295 Say N if unsure.
1297 config CPU_NOTIFIER_ERROR_INJECT
1298 tristate "CPU notifier error injection module"
1299 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1300 help
1301 This option provides a kernel module that can be used to test
1302 the error handling of the cpu notifiers by injecting artificial
1303 errors to CPU notifier chain callbacks. It is controlled through
1304 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1306 If the notifier call chain should be failed with some events
1307 notified, write the error code to "actions/<notifier event>/error".
1309 Example: Inject CPU offline error (-1 == -EPERM)
1311 # cd /sys/kernel/debug/notifier-error-inject/cpu
1312 # echo -1 > actions/CPU_DOWN_PREPARE/error
1313 # echo 0 > /sys/devices/system/cpu/cpu1/online
1314 bash: echo: write error: Operation not permitted
1316 To compile this code as a module, choose M here: the module will
1317 be called cpu-notifier-error-inject.
1319 If unsure, say N.
1321 config PM_NOTIFIER_ERROR_INJECT
1322 tristate "PM notifier error injection module"
1323 depends on PM && NOTIFIER_ERROR_INJECTION
1324 default m if PM_DEBUG
1325 help
1326 This option provides the ability to inject artificial errors to
1327 PM notifier chain callbacks. It is controlled through debugfs
1328 interface /sys/kernel/debug/notifier-error-inject/pm
1330 If the notifier call chain should be failed with some events
1331 notified, write the error code to "actions/<notifier event>/error".
1333 Example: Inject PM suspend error (-12 = -ENOMEM)
1335 # cd /sys/kernel/debug/notifier-error-inject/pm/
1336 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1337 # echo mem > /sys/power/state
1338 bash: echo: write error: Cannot allocate memory
1340 To compile this code as a module, choose M here: the module will
1341 be called pm-notifier-error-inject.
1343 If unsure, say N.
1345 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1346 tristate "OF reconfig notifier error injection module"
1347 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1348 help
1349 This option provides the ability to inject artificial errors to
1350 OF reconfig notifier chain callbacks. It is controlled
1351 through debugfs interface under
1352 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1354 If the notifier call chain should be failed with some events
1355 notified, write the error code to "actions/<notifier event>/error".
1357 To compile this code as a module, choose M here: the module will
1358 be called of-reconfig-notifier-error-inject.
1360 If unsure, say N.
1362 config FAULT_INJECTION
1363 bool "Fault-injection framework"
1364 depends on DEBUG_KERNEL
1365 help
1366 Provide fault-injection framework.
1367 For more details, see Documentation/fault-injection/.
1369 config FAILSLAB
1370 bool "Fault-injection capability for kmalloc"
1371 depends on FAULT_INJECTION
1372 depends on SLAB || SLUB
1373 help
1374 Provide fault-injection capability for kmalloc.
1376 config FAIL_PAGE_ALLOC
1377 bool "Fault-injection capabilitiy for alloc_pages()"
1378 depends on FAULT_INJECTION
1379 help
1380 Provide fault-injection capability for alloc_pages().
1382 config FAIL_MAKE_REQUEST
1383 bool "Fault-injection capability for disk IO"
1384 depends on FAULT_INJECTION && BLOCK
1385 help
1386 Provide fault-injection capability for disk IO.
1388 config FAIL_IO_TIMEOUT
1389 bool "Fault-injection capability for faking disk interrupts"
1390 depends on FAULT_INJECTION && BLOCK
1391 help
1392 Provide fault-injection capability on end IO handling. This
1393 will make the block layer "forget" an interrupt as configured,
1394 thus exercising the error handling.
1396 Only works with drivers that use the generic timeout handling,
1397 for others it wont do anything.
1399 config FAIL_MMC_REQUEST
1400 bool "Fault-injection capability for MMC IO"
1401 select DEBUG_FS
1402 depends on FAULT_INJECTION && MMC
1403 help
1404 Provide fault-injection capability for MMC IO.
1405 This will make the mmc core return data errors. This is
1406 useful to test the error handling in the mmc block device
1407 and to test how the mmc host driver handles retries from
1408 the block device.
1410 config FAULT_INJECTION_DEBUG_FS
1411 bool "Debugfs entries for fault-injection capabilities"
1412 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1413 help
1414 Enable configuration of fault-injection capabilities via debugfs.
1416 config FAULT_INJECTION_STACKTRACE_FILTER
1417 bool "stacktrace filter for fault-injection capabilities"
1418 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1419 depends on !X86_64
1420 select STACKTRACE
1421 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1422 help
1423 Provide stacktrace filter for fault-injection capabilities
1425 config LATENCYTOP
1426 bool "Latency measuring infrastructure"
1427 depends on HAVE_LATENCYTOP_SUPPORT
1428 depends on DEBUG_KERNEL
1429 depends on STACKTRACE_SUPPORT
1430 depends on PROC_FS
1431 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1432 select KALLSYMS
1433 select KALLSYMS_ALL
1434 select STACKTRACE
1435 select SCHEDSTATS
1436 select SCHED_DEBUG
1437 help
1438 Enable this option if you want to use the LatencyTOP tool
1439 to find out which userspace is blocking on what kernel operations.
1441 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1442 bool
1444 config DEBUG_STRICT_USER_COPY_CHECKS
1445 bool "Strict user copy size checks"
1446 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1447 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1448 help
1449 Enabling this option turns a certain set of sanity checks for user
1450 copy operations into compile time failures.
1452 The copy_from_user() etc checks are there to help test if there
1453 are sufficient security checks on the length argument of
1454 the copy operation, by having gcc prove that the argument is
1455 within bounds.
1457 If unsure, say N.
1459 source kernel/trace/Kconfig
1461 menu "Runtime Testing"
1463 config LKDTM
1464 tristate "Linux Kernel Dump Test Tool Module"
1465 depends on DEBUG_FS
1466 depends on BLOCK
1467 default n
1468 help
1469 This module enables testing of the different dumping mechanisms by
1470 inducing system failures at predefined crash points.
1471 If you don't need it: say N
1472 Choose M here to compile this code as a module. The module will be
1473 called lkdtm.
1475 Documentation on how to use the module can be found in
1476 Documentation/fault-injection/provoke-crashes.txt
1478 config TEST_LIST_SORT
1479 bool "Linked list sorting test"
1480 depends on DEBUG_KERNEL
1481 help
1482 Enable this to turn on 'list_sort()' function test. This test is
1483 executed only once during system boot, so affects only boot time.
1485 If unsure, say N.
1487 config KPROBES_SANITY_TEST
1488 bool "Kprobes sanity tests"
1489 depends on DEBUG_KERNEL
1490 depends on KPROBES
1491 default n
1492 help
1493 This option provides for testing basic kprobes functionality on
1494 boot. A sample kprobe, jprobe and kretprobe are inserted and
1495 verified for functionality.
1497 Say N if you are unsure.
1499 config BACKTRACE_SELF_TEST
1500 tristate "Self test for the backtrace code"
1501 depends on DEBUG_KERNEL
1502 default n
1503 help
1504 This option provides a kernel module that can be used to test
1505 the kernel stack backtrace code. This option is not useful
1506 for distributions or general kernels, but only for kernel
1507 developers working on architecture code.
1509 Note that if you want to also test saved backtraces, you will
1510 have to enable STACKTRACE as well.
1512 Say N if you are unsure.
1514 config RBTREE_TEST
1515 tristate "Red-Black tree test"
1516 depends on DEBUG_KERNEL
1517 help
1518 A benchmark measuring the performance of the rbtree library.
1519 Also includes rbtree invariant checks.
1521 config INTERVAL_TREE_TEST
1522 tristate "Interval tree test"
1523 depends on m && DEBUG_KERNEL
1524 select INTERVAL_TREE
1525 help
1526 A benchmark measuring the performance of the interval tree library
1528 config PERCPU_TEST
1529 tristate "Per cpu operations test"
1530 depends on m && DEBUG_KERNEL
1531 help
1532 Enable this option to build test module which validates per-cpu
1533 operations.
1535 If unsure, say N.
1537 config ATOMIC64_SELFTEST
1538 bool "Perform an atomic64_t self-test at boot"
1539 help
1540 Enable this option to test the atomic64_t functions at boot.
1542 If unsure, say N.
1544 config ASYNC_RAID6_TEST
1545 tristate "Self test for hardware accelerated raid6 recovery"
1546 depends on ASYNC_RAID6_RECOV
1547 select ASYNC_MEMCPY
1548 ---help---
1549 This is a one-shot self test that permutes through the
1550 recovery of all the possible two disk failure scenarios for a
1551 N-disk array. Recovery is performed with the asynchronous
1552 raid6 recovery routines, and will optionally use an offload
1553 engine if one is available.
1555 If unsure, say N.
1557 config TEST_STRING_HELPERS
1558 tristate "Test functions located in the string_helpers module at runtime"
1560 config TEST_KSTRTOX
1561 tristate "Test kstrto*() family of functions at runtime"
1563 config TEST_RHASHTABLE
1564 bool "Perform selftest on resizable hash table"
1565 default n
1566 help
1567 Enable this option to test the rhashtable functions at boot.
1569 If unsure, say N.
1571 endmenu # runtime tests
1573 config PROVIDE_OHCI1394_DMA_INIT
1574 bool "Remote debugging over FireWire early on boot"
1575 depends on PCI && X86
1576 help
1577 If you want to debug problems which hang or crash the kernel early
1578 on boot and the crashing machine has a FireWire port, you can use
1579 this feature to remotely access the memory of the crashed machine
1580 over FireWire. This employs remote DMA as part of the OHCI1394
1581 specification which is now the standard for FireWire controllers.
1583 With remote DMA, you can monitor the printk buffer remotely using
1584 firescope and access all memory below 4GB using fireproxy from gdb.
1585 Even controlling a kernel debugger is possible using remote DMA.
1587 Usage:
1589 If ohci1394_dma=early is used as boot parameter, it will initialize
1590 all OHCI1394 controllers which are found in the PCI config space.
1592 As all changes to the FireWire bus such as enabling and disabling
1593 devices cause a bus reset and thereby disable remote DMA for all
1594 devices, be sure to have the cable plugged and FireWire enabled on
1595 the debugging host before booting the debug target for debugging.
1597 This code (~1k) is freed after boot. By then, the firewire stack
1598 in charge of the OHCI-1394 controllers should be used instead.
1600 See Documentation/debugging-via-ohci1394.txt for more information.
1602 config BUILD_DOCSRC
1603 bool "Build targets in Documentation/ tree"
1604 depends on HEADERS_CHECK
1605 help
1606 This option attempts to build objects from the source files in the
1607 kernel Documentation/ tree.
1609 Say N if you are unsure.
1611 config DMA_API_DEBUG
1612 bool "Enable debugging of DMA-API usage"
1613 depends on HAVE_DMA_API_DEBUG
1614 help
1615 Enable this option to debug the use of the DMA API by device drivers.
1616 With this option you will be able to detect common bugs in device
1617 drivers like double-freeing of DMA mappings or freeing mappings that
1618 were never allocated.
1620 This also attempts to catch cases where a page owned by DMA is
1621 accessed by the cpu in a way that could cause data corruption. For
1622 example, this enables cow_user_page() to check that the source page is
1623 not undergoing DMA.
1625 This option causes a performance degradation. Use only if you want to
1626 debug device drivers and dma interactions.
1628 If unsure, say N.
1630 config TEST_MODULE
1631 tristate "Test module loading with 'hello world' module"
1632 default n
1633 depends on m
1634 help
1635 This builds the "test_module" module that emits "Hello, world"
1636 on printk when loaded. It is designed to be used for basic
1637 evaluation of the module loading subsystem (for example when
1638 validating module verification). It lacks any extra dependencies,
1639 and will not normally be loaded by the system unless explicitly
1640 requested by name.
1642 If unsure, say N.
1644 config TEST_USER_COPY
1645 tristate "Test user/kernel boundary protections"
1646 default n
1647 depends on m
1648 help
1649 This builds the "test_user_copy" module that runs sanity checks
1650 on the copy_to/from_user infrastructure, making sure basic
1651 user/kernel boundary testing is working. If it fails to load,
1652 a regression has been detected in the user/kernel memory boundary
1653 protections.
1655 If unsure, say N.
1657 config TEST_BPF
1658 tristate "Test BPF filter functionality"
1659 default n
1660 depends on m && NET
1661 help
1662 This builds the "test_bpf" module that runs various test vectors
1663 against the BPF interpreter or BPF JIT compiler depending on the
1664 current setting. This is in particular useful for BPF JIT compiler
1665 development, but also to run regression tests against changes in
1666 the interpreter code.
1668 If unsure, say N.
1670 config TEST_FIRMWARE
1671 tristate "Test firmware loading via userspace interface"
1672 default n
1673 depends on FW_LOADER
1674 help
1675 This builds the "test_firmware" module that creates a userspace
1676 interface for testing firmware loading. This can be used to
1677 control the triggering of firmware loading without needing an
1678 actual firmware-using device. The contents can be rechecked by
1679 userspace.
1681 If unsure, say N.
1683 config TEST_UDELAY
1684 tristate "udelay test driver"
1685 default n
1686 help
1687 This builds the "udelay_test" module that helps to make sure
1688 that udelay() is working properly.
1690 If unsure, say N.
1692 source "samples/Kconfig"
1694 source "lib/Kconfig.kgdb"