| blob | 910355da9d143718447062579da7a746bad701bf |
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 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 ENABLE_WARN_DEPRECATED
162 bool "Enable __deprecated logic"
163 default y
164 help
165 Enable the __deprecated logic in the kernel build.
166 Disable this to suppress the "warning: 'foo' is deprecated
167 (declared at kernel/power/somefile.c:1234)" messages.
169 config ENABLE_MUST_CHECK
170 bool "Enable __must_check logic"
171 default y
172 help
173 Enable the __must_check logic in the kernel build. Disable this to
174 suppress the "warning: ignoring return value of 'foo', declared with
175 attribute warn_unused_result" messages.
177 config FRAME_WARN
178 int "Warn for stack frames larger than (needs gcc 4.4)"
179 range 0 8192
180 default 1024 if !64BIT
181 default 2048 if 64BIT
182 help
183 Tell gcc to warn at build time for stack frames larger than this.
184 Setting this too low will cause a lot of warnings.
185 Setting it to 0 disables the warning.
186 Requires gcc 4.4
188 config STRIP_ASM_SYMS
189 bool "Strip assembler-generated symbols during link"
190 default n
191 help
192 Strip internal assembler-generated symbols during a link (symbols
193 that look like '.Lxxx') so they don't pollute the output of
194 get_wchan() and suchlike.
196 config READABLE_ASM
197 bool "Generate readable assembler code"
198 depends on DEBUG_KERNEL
199 help
200 Disable some compiler optimizations that tend to generate human unreadable
201 assembler output. This may make the kernel slightly slower, but it helps
202 to keep kernel developers who have to stare a lot at assembler listings
203 sane.
205 config UNUSED_SYMBOLS
206 bool "Enable unused/obsolete exported symbols"
207 default y if X86
208 help
209 Unused but exported symbols make the kernel needlessly bigger. For
210 that reason most of these unused exports will soon be removed. This
211 option is provided temporarily to provide a transition period in case
212 some external kernel module needs one of these symbols anyway. If you
213 encounter such a case in your module, consider if you are actually
214 using the right API. (rationale: since nobody in the kernel is using
215 this in a module, there is a pretty good chance it's actually the
216 wrong interface to use). If you really need the symbol, please send a
217 mail to the linux kernel mailing list mentioning the symbol and why
218 you really need it, and what the merge plan to the mainline kernel for
219 your module is.
221 config DEBUG_FS
222 bool "Debug Filesystem"
223 help
224 debugfs is a virtual file system that kernel developers use to put
225 debugging files into. Enable this option to be able to read and
226 write to these files.
228 For detailed documentation on the debugfs API, see
229 Documentation/DocBook/filesystems.
231 If unsure, say N.
233 config HEADERS_CHECK
234 bool "Run 'make headers_check' when building vmlinux"
235 depends on !UML
236 help
237 This option will extract the user-visible kernel headers whenever
238 building the kernel, and will run basic sanity checks on them to
239 ensure that exported files do not attempt to include files which
240 were not exported, etc.
242 If you're making modifications to header files which are
243 relevant for userspace, say 'Y', and check the headers
244 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
245 your build tree), to make sure they're suitable.
247 config DEBUG_SECTION_MISMATCH
248 bool "Enable full Section mismatch analysis"
249 help
250 The section mismatch analysis checks if there are illegal
251 references from one section to another section.
252 During linktime or runtime, some sections are dropped;
253 any use of code/data previously in these sections would
254 most likely result in an oops.
255 In the code, functions and variables are annotated with
256 __init,, etc. (see the full list in include/linux/init.h),
257 which results in the code/data being placed in specific sections.
258 The section mismatch analysis is always performed after a full
259 kernel build, and enabling this option causes the following
260 additional steps to occur:
261 - Add the option -fno-inline-functions-called-once to gcc commands.
262 When inlining a function annotated with __init in a non-init
263 function, we would lose the section information and thus
264 the analysis would not catch the illegal reference.
265 This option tells gcc to inline less (but it does result in
266 a larger kernel).
267 - Run the section mismatch analysis for each module/built-in.o file.
268 When we run the section mismatch analysis on vmlinux.o, we
269 lose valueble information about where the mismatch was
270 introduced.
271 Running the analysis for each module/built-in.o file
272 tells where the mismatch happens much closer to the
273 source. The drawback is that the same mismatch is
274 reported at least twice.
275 - Enable verbose reporting from modpost in order to help resolve
276 the section mismatches that are reported.
278 #
279 # Select this config option from the architecture Kconfig, if it
280 # is preferred to always offer frame pointers as a config
281 # option on the architecture (regardless of KERNEL_DEBUG):
282 #
283 config ARCH_WANT_FRAME_POINTERS
284 bool
285 help
287 config FRAME_POINTER
288 bool "Compile the kernel with frame pointers"
289 depends on DEBUG_KERNEL && \
290 (CRIS || M68K || FRV || UML || \
291 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
292 ARCH_WANT_FRAME_POINTERS
293 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
294 help
295 If you say Y here the resulting kernel image will be slightly
296 larger and slower, but it gives very useful debugging information
297 in case of kernel bugs. (precise oopses/stacktraces/warnings)
299 config DEBUG_FORCE_WEAK_PER_CPU
300 bool "Force weak per-cpu definitions"
301 depends on DEBUG_KERNEL
302 help
303 s390 and alpha require percpu variables in modules to be
304 defined weak to work around addressing range issue which
305 puts the following two restrictions on percpu variable
306 definitions.
308 1. percpu symbols must be unique whether static or not
309 2. percpu variables can't be defined inside a function
311 To ensure that generic code follows the above rules, this
312 option forces all percpu variables to be defined as weak.
314 endmenu # "Compiler options"
316 config MAGIC_SYSRQ
317 bool "Magic SysRq key"
318 depends on !UML
319 help
320 If you say Y here, you will have some control over the system even
321 if the system crashes for example during kernel debugging (e.g., you
322 will be able to flush the buffer cache to disk, reboot the system
323 immediately or dump some status information). This is accomplished
324 by pressing various keys while holding SysRq (Alt+PrintScreen). It
325 also works on a serial console (on PC hardware at least), if you
326 send a BREAK and then within 5 seconds a command keypress. The
327 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
328 unless you really know what this hack does.
330 config MAGIC_SYSRQ_DEFAULT_ENABLE
331 hex "Enable magic SysRq key functions by default"
332 depends on MAGIC_SYSRQ
333 default 0x1
334 help
335 Specifies which SysRq key functions are enabled by default.
336 This may be set to 1 or 0 to enable or disable them all, or
337 to a bitmask as described in Documentation/sysrq.txt.
339 config DEBUG_KERNEL
340 bool "Kernel debugging"
341 help
342 Say Y here if you are developing drivers or trying to debug and
343 identify kernel problems.
345 menu "Memory Debugging"
347 source mm/Kconfig.debug
349 config DEBUG_OBJECTS
350 bool "Debug object operations"
351 depends on DEBUG_KERNEL
352 help
353 If you say Y here, additional code will be inserted into the
354 kernel to track the life time of various objects and validate
355 the operations on those objects.
357 config DEBUG_OBJECTS_SELFTEST
358 bool "Debug objects selftest"
359 depends on DEBUG_OBJECTS
360 help
361 This enables the selftest of the object debug code.
363 config DEBUG_OBJECTS_FREE
364 bool "Debug objects in freed memory"
365 depends on DEBUG_OBJECTS
366 help
367 This enables checks whether a k/v free operation frees an area
368 which contains an object which has not been deactivated
369 properly. This can make kmalloc/kfree-intensive workloads
370 much slower.
372 config DEBUG_OBJECTS_TIMERS
373 bool "Debug timer objects"
374 depends on DEBUG_OBJECTS
375 help
376 If you say Y here, additional code will be inserted into the
377 timer routines to track the life time of timer objects and
378 validate the timer operations.
380 config DEBUG_OBJECTS_WORK
381 bool "Debug work objects"
382 depends on DEBUG_OBJECTS
383 help
384 If you say Y here, additional code will be inserted into the
385 work queue routines to track the life time of work objects and
386 validate the work operations.
388 config DEBUG_OBJECTS_RCU_HEAD
389 bool "Debug RCU callbacks objects"
390 depends on DEBUG_OBJECTS
391 help
392 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
394 config DEBUG_OBJECTS_PERCPU_COUNTER
395 bool "Debug percpu counter objects"
396 depends on DEBUG_OBJECTS
397 help
398 If you say Y here, additional code will be inserted into the
399 percpu counter routines to track the life time of percpu counter
400 objects and validate the percpu counter operations.
402 config DEBUG_OBJECTS_ENABLE_DEFAULT
403 int "debug_objects bootup default value (0-1)"
404 range 0 1
405 default "1"
406 depends on DEBUG_OBJECTS
407 help
408 Debug objects boot parameter default value
410 config DEBUG_SLAB
411 bool "Debug slab memory allocations"
412 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
413 help
414 Say Y here to have the kernel do limited verification on memory
415 allocation as well as poisoning memory on free to catch use of freed
416 memory. This can make kmalloc/kfree-intensive workloads much slower.
418 config DEBUG_SLAB_LEAK
419 bool "Memory leak debugging"
420 depends on DEBUG_SLAB
422 config SLUB_DEBUG_ON
423 bool "SLUB debugging on by default"
424 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
425 default n
426 help
427 Boot with debugging on by default. SLUB boots by default with
428 the runtime debug capabilities switched off. Enabling this is
429 equivalent to specifying the "slub_debug" parameter on boot.
430 There is no support for more fine grained debug control like
431 possible with slub_debug=xxx. SLUB debugging may be switched
432 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
433 "slub_debug=-".
435 config SLUB_STATS
436 default n
437 bool "Enable SLUB performance statistics"
438 depends on SLUB && SYSFS
439 help
440 SLUB statistics are useful to debug SLUBs allocation behavior in
441 order find ways to optimize the allocator. This should never be
442 enabled for production use since keeping statistics slows down
443 the allocator by a few percentage points. The slabinfo command
444 supports the determination of the most active slabs to figure
445 out which slabs are relevant to a particular load.
446 Try running: slabinfo -DA
448 config HAVE_DEBUG_KMEMLEAK
449 bool
451 config DEBUG_KMEMLEAK
452 bool "Kernel memory leak detector"
453 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
454 select DEBUG_FS
455 select STACKTRACE if STACKTRACE_SUPPORT
456 select KALLSYMS
457 select CRC32
458 help
459 Say Y here if you want to enable the memory leak
460 detector. The memory allocation/freeing is traced in a way
461 similar to the Boehm's conservative garbage collector, the
462 difference being that the orphan objects are not freed but
463 only shown in /sys/kernel/debug/kmemleak. Enabling this
464 feature will introduce an overhead to memory
465 allocations. See Documentation/kmemleak.txt for more
466 details.
468 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
469 of finding leaks due to the slab objects poisoning.
471 In order to access the kmemleak file, debugfs needs to be
472 mounted (usually at /sys/kernel/debug).
474 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
475 int "Maximum kmemleak early log entries"
476 depends on DEBUG_KMEMLEAK
477 range 200 40000
478 default 400
479 help
480 Kmemleak must track all the memory allocations to avoid
481 reporting false positives. Since memory may be allocated or
482 freed before kmemleak is initialised, an early log buffer is
483 used to store these actions. If kmemleak reports "early log
484 buffer exceeded", please increase this value.
486 config DEBUG_KMEMLEAK_TEST
487 tristate "Simple test for the kernel memory leak detector"
488 depends on DEBUG_KMEMLEAK && m
489 help
490 This option enables a module that explicitly leaks memory.
492 If unsure, say N.
494 config DEBUG_KMEMLEAK_DEFAULT_OFF
495 bool "Default kmemleak to off"
496 depends on DEBUG_KMEMLEAK
497 help
498 Say Y here to disable kmemleak by default. It can then be enabled
499 on the command line via kmemleak=on.
501 config DEBUG_STACK_USAGE
502 bool "Stack utilization instrumentation"
503 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
504 help
505 Enables the display of the minimum amount of free stack which each
506 task has ever had available in the sysrq-T and sysrq-P debug output.
508 This option will slow down process creation somewhat.
510 config DEBUG_VM
511 bool "Debug VM"
512 depends on DEBUG_KERNEL
513 help
514 Enable this to turn on extended checks in the virtual-memory system
515 that may impact performance.
517 If unsure, say N.
519 config DEBUG_VM_VMACACHE
520 bool "Debug VMA caching"
521 depends on DEBUG_VM
522 help
523 Enable this to turn on VMA caching debug information. Doing so
524 can cause significant overhead, so only enable it in non-production
525 environments.
527 If unsure, say N.
529 config DEBUG_VM_RB
530 bool "Debug VM red-black trees"
531 depends on DEBUG_VM
532 help
533 Enable VM red-black tree debugging information and extra validations.
535 If unsure, say N.
537 config DEBUG_VIRTUAL
538 bool "Debug VM translations"
539 depends on DEBUG_KERNEL && X86
540 help
541 Enable some costly sanity checks in virtual to page code. This can
542 catch mistakes with virt_to_page() and friends.
544 If unsure, say N.
546 config DEBUG_NOMMU_REGIONS
547 bool "Debug the global anon/private NOMMU mapping region tree"
548 depends on DEBUG_KERNEL && !MMU
549 help
550 This option causes the global tree of anonymous and private mapping
551 regions to be regularly checked for invalid topology.
553 config DEBUG_MEMORY_INIT
554 bool "Debug memory initialisation" if EXPERT
555 default !EXPERT
556 help
557 Enable this for additional checks during memory initialisation.
558 The sanity checks verify aspects of the VM such as the memory model
559 and other information provided by the architecture. Verbose
560 information will be printed at KERN_DEBUG loglevel depending
561 on the mminit_loglevel= command-line option.
563 If unsure, say Y
565 config MEMORY_NOTIFIER_ERROR_INJECT
566 tristate "Memory hotplug notifier error injection module"
567 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
568 help
569 This option provides the ability to inject artificial errors to
570 memory hotplug notifier chain callbacks. It is controlled through
571 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
573 If the notifier call chain should be failed with some events
574 notified, write the error code to "actions/<notifier event>/error".
576 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
578 # cd /sys/kernel/debug/notifier-error-inject/memory
579 # echo -12 > actions/MEM_GOING_OFFLINE/error
580 # echo offline > /sys/devices/system/memory/memoryXXX/state
581 bash: echo: write error: Cannot allocate memory
583 To compile this code as a module, choose M here: the module will
584 be called memory-notifier-error-inject.
586 If unsure, say N.
588 config DEBUG_PER_CPU_MAPS
589 bool "Debug access to per_cpu maps"
590 depends on DEBUG_KERNEL
591 depends on SMP
592 help
593 Say Y to verify that the per_cpu map being accessed has
594 been set up. This adds a fair amount of code to kernel memory
595 and decreases performance.
597 Say N if unsure.
599 config DEBUG_HIGHMEM
600 bool "Highmem debugging"
601 depends on DEBUG_KERNEL && HIGHMEM
602 help
603 This option enables additional error checking for high memory
604 systems. Disable for production systems.
606 config HAVE_DEBUG_STACKOVERFLOW
607 bool
609 config DEBUG_STACKOVERFLOW
610 bool "Check for stack overflows"
611 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
612 ---help---
613 Say Y here if you want to check for overflows of kernel, IRQ
614 and exception stacks (if your archicture uses them). This
615 option will show detailed messages if free stack space drops
616 below a certain limit.
618 These kinds of bugs usually occur when call-chains in the
619 kernel get too deep, especially when interrupts are
620 involved.
622 Use this in cases where you see apparently random memory
623 corruption, especially if it appears in 'struct thread_info'
625 If in doubt, say "N".
627 source "lib/Kconfig.kmemcheck"
629 endmenu # "Memory Debugging"
631 config DEBUG_SHIRQ
632 bool "Debug shared IRQ handlers"
633 depends on DEBUG_KERNEL
634 help
635 Enable this to generate a spurious interrupt as soon as a shared
636 interrupt handler is registered, and just before one is deregistered.
637 Drivers ought to be able to handle interrupts coming in at those
638 points; some don't and need to be caught.
640 menu "Debug Lockups and Hangs"
642 config LOCKUP_DETECTOR
643 bool "Detect Hard and Soft Lockups"
644 depends on DEBUG_KERNEL && !S390
645 help
646 Say Y here to enable the kernel to act as a watchdog to detect
647 hard and soft lockups.
649 Softlockups are bugs that cause the kernel to loop in kernel
650 mode for more than 20 seconds, without giving other tasks a
651 chance to run. The current stack trace is displayed upon
652 detection and the system will stay locked up.
654 Hardlockups are bugs that cause the CPU to loop in kernel mode
655 for more than 10 seconds, without letting other interrupts have a
656 chance to run. The current stack trace is displayed upon detection
657 and the system will stay locked up.
659 The overhead should be minimal. A periodic hrtimer runs to
660 generate interrupts and kick the watchdog task every 4 seconds.
661 An NMI is generated every 10 seconds or so to check for hardlockups.
663 The frequency of hrtimer and NMI events and the soft and hard lockup
664 thresholds can be controlled through the sysctl watchdog_thresh.
666 config HARDLOCKUP_DETECTOR
667 def_bool y
668 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
669 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
671 config BOOTPARAM_HARDLOCKUP_PANIC
672 bool "Panic (Reboot) On Hard Lockups"
673 depends on HARDLOCKUP_DETECTOR
674 help
675 Say Y here to enable the kernel to panic on "hard lockups",
676 which are bugs that cause the kernel to loop in kernel
677 mode with interrupts disabled for more than 10 seconds (configurable
678 using the watchdog_thresh sysctl).
680 Say N if unsure.
682 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
683 int
684 depends on HARDLOCKUP_DETECTOR
685 range 0 1
686 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
687 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
689 config BOOTPARAM_SOFTLOCKUP_PANIC
690 bool "Panic (Reboot) On Soft Lockups"
691 depends on LOCKUP_DETECTOR
692 help
693 Say Y here to enable the kernel to panic on "soft lockups",
694 which are bugs that cause the kernel to loop in kernel
695 mode for more than 20 seconds (configurable using the watchdog_thresh
696 sysctl), without giving other tasks a chance to run.
698 The panic can be used in combination with panic_timeout,
699 to cause the system to reboot automatically after a
700 lockup has been detected. This feature is useful for
701 high-availability systems that have uptime guarantees and
702 where a lockup must be resolved ASAP.
704 Say N if unsure.
706 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
707 int
708 depends on LOCKUP_DETECTOR
709 range 0 1
710 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
711 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
713 config DETECT_HUNG_TASK
714 bool "Detect Hung Tasks"
715 depends on DEBUG_KERNEL
716 default LOCKUP_DETECTOR
717 help
718 Say Y here to enable the kernel to detect "hung tasks",
719 which are bugs that cause the task to be stuck in
720 uninterruptible "D" state indefinitiley.
722 When a hung task is detected, the kernel will print the
723 current stack trace (which you should report), but the
724 task will stay in uninterruptible state. If lockdep is
725 enabled then all held locks will also be reported. This
726 feature has negligible overhead.
728 config DEFAULT_HUNG_TASK_TIMEOUT
729 int "Default timeout for hung task detection (in seconds)"
730 depends on DETECT_HUNG_TASK
731 default 120
732 help
733 This option controls the default timeout (in seconds) used
734 to determine when a task has become non-responsive and should
735 be considered hung.
737 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
738 sysctl or by writing a value to
739 /proc/sys/kernel/hung_task_timeout_secs.
741 A timeout of 0 disables the check. The default is two minutes.
742 Keeping the default should be fine in most cases.
744 config BOOTPARAM_HUNG_TASK_PANIC
745 bool "Panic (Reboot) On Hung Tasks"
746 depends on DETECT_HUNG_TASK
747 help
748 Say Y here to enable the kernel to panic on "hung tasks",
749 which are bugs that cause the kernel to leave a task stuck
750 in uninterruptible "D" state.
752 The panic can be used in combination with panic_timeout,
753 to cause the system to reboot automatically after a
754 hung task has been detected. This feature is useful for
755 high-availability systems that have uptime guarantees and
756 where a hung tasks must be resolved ASAP.
758 Say N if unsure.
760 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
761 int
762 depends on DETECT_HUNG_TASK
763 range 0 1
764 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
765 default 1 if BOOTPARAM_HUNG_TASK_PANIC
767 endmenu # "Debug lockups and hangs"
769 config PANIC_ON_OOPS
770 bool "Panic on Oops"
771 help
772 Say Y here to enable the kernel to panic when it oopses. This
773 has the same effect as setting oops=panic on the kernel command
774 line.
776 This feature is useful to ensure that the kernel does not do
777 anything erroneous after an oops which could result in data
778 corruption or other issues.
780 Say N if unsure.
782 config PANIC_ON_OOPS_VALUE
783 int
784 range 0 1
785 default 0 if !PANIC_ON_OOPS
786 default 1 if PANIC_ON_OOPS
788 config PANIC_TIMEOUT
789 int "panic timeout"
790 default 0
791 help
792 Set the timeout value (in seconds) until a reboot occurs when the
793 the kernel panics. If n = 0, then we wait forever. A timeout
794 value n > 0 will wait n seconds before rebooting, while a timeout
795 value n < 0 will reboot immediately.
797 config SCHED_DEBUG
798 bool "Collect scheduler debugging info"
799 depends on DEBUG_KERNEL && PROC_FS
800 default y
801 help
802 If you say Y here, the /proc/sched_debug file will be provided
803 that can help debug the scheduler. The runtime overhead of this
804 option is minimal.
806 config SCHEDSTATS
807 bool "Collect scheduler statistics"
808 depends on DEBUG_KERNEL && PROC_FS
809 help
810 If you say Y here, additional code will be inserted into the
811 scheduler and related routines to collect statistics about
812 scheduler behavior and provide them in /proc/schedstat. These
813 stats may be useful for both tuning and debugging the scheduler
814 If you aren't debugging the scheduler or trying to tune a specific
815 application, you can say N to avoid the very slight overhead
816 this adds.
818 config TIMER_STATS
819 bool "Collect kernel timers statistics"
820 depends on DEBUG_KERNEL && PROC_FS
821 help
822 If you say Y here, additional code will be inserted into the
823 timer routines to collect statistics about kernel timers being
824 reprogrammed. The statistics can be read from /proc/timer_stats.
825 The statistics collection is started by writing 1 to /proc/timer_stats,
826 writing 0 stops it. This feature is useful to collect information
827 about timer usage patterns in kernel and userspace. This feature
828 is lightweight if enabled in the kernel config but not activated
829 (it defaults to deactivated on bootup and will only be activated
830 if some application like powertop activates it explicitly).
832 config DEBUG_PREEMPT
833 bool "Debug preemptible kernel"
834 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
835 default y
836 help
837 If you say Y here then the kernel will use a debug variant of the
838 commonly used smp_processor_id() function and will print warnings
839 if kernel code uses it in a preemption-unsafe way. Also, the kernel
840 will detect preemption count underflows.
842 menu "Lock Debugging (spinlocks, mutexes, etc...)"
844 config DEBUG_RT_MUTEXES
845 bool "RT Mutex debugging, deadlock detection"
846 depends on DEBUG_KERNEL && RT_MUTEXES
847 help
848 This allows rt mutex semantics violations and rt mutex related
849 deadlocks (lockups) to be detected and reported automatically.
851 config RT_MUTEX_TESTER
852 bool "Built-in scriptable tester for rt-mutexes"
853 depends on DEBUG_KERNEL && RT_MUTEXES
854 help
855 This option enables a rt-mutex tester.
857 config DEBUG_SPINLOCK
858 bool "Spinlock and rw-lock debugging: basic checks"
859 depends on DEBUG_KERNEL
860 select UNINLINE_SPIN_UNLOCK
861 help
862 Say Y here and build SMP to catch missing spinlock initialization
863 and certain other kinds of spinlock errors commonly made. This is
864 best used in conjunction with the NMI watchdog so that spinlock
865 deadlocks are also debuggable.
867 config DEBUG_MUTEXES
868 bool "Mutex debugging: basic checks"
869 depends on DEBUG_KERNEL
870 help
871 This feature allows mutex semantics violations to be detected and
872 reported.
874 config DEBUG_WW_MUTEX_SLOWPATH
875 bool "Wait/wound mutex debugging: Slowpath testing"
876 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
877 select DEBUG_LOCK_ALLOC
878 select DEBUG_SPINLOCK
879 select DEBUG_MUTEXES
880 help
881 This feature enables slowpath testing for w/w mutex users by
882 injecting additional -EDEADLK wound/backoff cases. Together with
883 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
884 will test all possible w/w mutex interface abuse with the
885 exception of simply not acquiring all the required locks.
887 config DEBUG_LOCK_ALLOC
888 bool "Lock debugging: detect incorrect freeing of live locks"
889 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
890 select DEBUG_SPINLOCK
891 select DEBUG_MUTEXES
892 select LOCKDEP
893 help
894 This feature will check whether any held lock (spinlock, rwlock,
895 mutex or rwsem) is incorrectly freed by the kernel, via any of the
896 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
897 vfree(), etc.), whether a live lock is incorrectly reinitialized via
898 spin_lock_init()/mutex_init()/etc., or whether there is any lock
899 held during task exit.
901 config PROVE_LOCKING
902 bool "Lock debugging: prove locking correctness"
903 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
904 select LOCKDEP
905 select DEBUG_SPINLOCK
906 select DEBUG_MUTEXES
907 select DEBUG_LOCK_ALLOC
908 select TRACE_IRQFLAGS
909 default n
910 help
911 This feature enables the kernel to prove that all locking
912 that occurs in the kernel runtime is mathematically
913 correct: that under no circumstance could an arbitrary (and
914 not yet triggered) combination of observed locking
915 sequences (on an arbitrary number of CPUs, running an
916 arbitrary number of tasks and interrupt contexts) cause a
917 deadlock.
919 In short, this feature enables the kernel to report locking
920 related deadlocks before they actually occur.
922 The proof does not depend on how hard and complex a
923 deadlock scenario would be to trigger: how many
924 participant CPUs, tasks and irq-contexts would be needed
925 for it to trigger. The proof also does not depend on
926 timing: if a race and a resulting deadlock is possible
927 theoretically (no matter how unlikely the race scenario
928 is), it will be proven so and will immediately be
929 reported by the kernel (once the event is observed that
930 makes the deadlock theoretically possible).
932 If a deadlock is impossible (i.e. the locking rules, as
933 observed by the kernel, are mathematically correct), the
934 kernel reports nothing.
936 NOTE: this feature can also be enabled for rwlocks, mutexes
937 and rwsems - in which case all dependencies between these
938 different locking variants are observed and mapped too, and
939 the proof of observed correctness is also maintained for an
940 arbitrary combination of these separate locking variants.
942 For more details, see Documentation/lockdep-design.txt.
944 config LOCKDEP
945 bool
946 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
947 select STACKTRACE
948 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC
949 select KALLSYMS
950 select KALLSYMS_ALL
952 config LOCK_STAT
953 bool "Lock usage statistics"
954 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
955 select LOCKDEP
956 select DEBUG_SPINLOCK
957 select DEBUG_MUTEXES
958 select DEBUG_LOCK_ALLOC
959 default n
960 help
961 This feature enables tracking lock contention points
963 For more details, see Documentation/lockstat.txt
965 This also enables lock events required by "perf lock",
966 subcommand of perf.
967 If you want to use "perf lock", you also need to turn on
968 CONFIG_EVENT_TRACING.
970 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
971 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
973 config DEBUG_LOCKDEP
974 bool "Lock dependency engine debugging"
975 depends on DEBUG_KERNEL && LOCKDEP
976 help
977 If you say Y here, the lock dependency engine will do
978 additional runtime checks to debug itself, at the price
979 of more runtime overhead.
981 config DEBUG_ATOMIC_SLEEP
982 bool "Sleep inside atomic section checking"
983 select PREEMPT_COUNT
984 depends on DEBUG_KERNEL
985 help
986 If you say Y here, various routines which may sleep will become very
987 noisy if they are called inside atomic sections: when a spinlock is
988 held, inside an rcu read side critical section, inside preempt disabled
989 sections, inside an interrupt, etc...
991 config DEBUG_LOCKING_API_SELFTESTS
992 bool "Locking API boot-time self-tests"
993 depends on DEBUG_KERNEL
994 help
995 Say Y here if you want the kernel to run a short self-test during
996 bootup. The self-test checks whether common types of locking bugs
997 are detected by debugging mechanisms or not. (if you disable
998 lock debugging then those bugs wont be detected of course.)
999 The following locking APIs are covered: spinlocks, rwlocks,
1000 mutexes and rwsems.
1002 config LOCK_TORTURE_TEST
1003 tristate "torture tests for locking"
1004 depends on DEBUG_KERNEL
1005 select TORTURE_TEST
1006 default n
1007 help
1008 This option provides a kernel module that runs torture tests
1009 on kernel locking primitives. The kernel module may be built
1010 after the fact on the running kernel to be tested, if desired.
1012 Say Y here if you want kernel locking-primitive torture tests
1013 to be built into the kernel.
1014 Say M if you want these torture tests to build as a module.
1015 Say N if you are unsure.
1017 endmenu # lock debugging
1019 config TRACE_IRQFLAGS
1020 bool
1021 help
1022 Enables hooks to interrupt enabling and disabling for
1023 either tracing or lock debugging.
1025 config STACKTRACE
1026 bool
1027 depends on STACKTRACE_SUPPORT
1029 config DEBUG_KOBJECT
1030 bool "kobject debugging"
1031 depends on DEBUG_KERNEL
1032 help
1033 If you say Y here, some extra kobject debugging messages will be sent
1034 to the syslog.
1036 config DEBUG_KOBJECT_RELEASE
1037 bool "kobject release debugging"
1038 depends on DEBUG_OBJECTS_TIMERS
1039 help
1040 kobjects are reference counted objects. This means that their
1041 last reference count put is not predictable, and the kobject can
1042 live on past the point at which a driver decides to drop it's
1043 initial reference to the kobject gained on allocation. An
1044 example of this would be a struct device which has just been
1045 unregistered.
1047 However, some buggy drivers assume that after such an operation,
1048 the memory backing the kobject can be immediately freed. This
1049 goes completely against the principles of a refcounted object.
1051 If you say Y here, the kernel will delay the release of kobjects
1052 on the last reference count to improve the visibility of this
1053 kind of kobject release bug.
1055 config HAVE_DEBUG_BUGVERBOSE
1056 bool
1058 config DEBUG_BUGVERBOSE
1059 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1060 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1061 default y
1062 help
1063 Say Y here to make BUG() panics output the file name and line number
1064 of the BUG call as well as the EIP and oops trace. This aids
1065 debugging but costs about 70-100K of memory.
1067 config DEBUG_LIST
1068 bool "Debug linked list manipulation"
1069 depends on DEBUG_KERNEL
1070 help
1071 Enable this to turn on extended checks in the linked-list
1072 walking routines.
1074 If unsure, say N.
1076 config DEBUG_PI_LIST
1077 bool "Debug priority linked list manipulation"
1078 depends on DEBUG_KERNEL
1079 help
1080 Enable this to turn on extended checks in the priority-ordered
1081 linked-list (plist) walking routines. This checks the entire
1082 list multiple times during each manipulation.
1084 If unsure, say N.
1086 config DEBUG_SG
1087 bool "Debug SG table operations"
1088 depends on DEBUG_KERNEL
1089 help
1090 Enable this to turn on checks on scatter-gather tables. This can
1091 help find problems with drivers that do not properly initialize
1092 their sg tables.
1094 If unsure, say N.
1096 config DEBUG_NOTIFIERS
1097 bool "Debug notifier call chains"
1098 depends on DEBUG_KERNEL
1099 help
1100 Enable this to turn on sanity checking for notifier call chains.
1101 This is most useful for kernel developers to make sure that
1102 modules properly unregister themselves from notifier chains.
1103 This is a relatively cheap check but if you care about maximum
1104 performance, say N.
1106 config DEBUG_CREDENTIALS
1107 bool "Debug credential management"
1108 depends on DEBUG_KERNEL
1109 help
1110 Enable this to turn on some debug checking for credential
1111 management. The additional code keeps track of the number of
1112 pointers from task_structs to any given cred struct, and checks to
1113 see that this number never exceeds the usage count of the cred
1114 struct.
1116 Furthermore, if SELinux is enabled, this also checks that the
1117 security pointer in the cred struct is never seen to be invalid.
1119 If unsure, say N.
1121 menu "RCU Debugging"
1123 config PROVE_RCU
1124 bool "RCU debugging: prove RCU correctness"
1125 depends on PROVE_LOCKING
1126 default n
1127 help
1128 This feature enables lockdep extensions that check for correct
1129 use of RCU APIs. This is currently under development. Say Y
1130 if you want to debug RCU usage or help work on the PROVE_RCU
1131 feature.
1133 Say N if you are unsure.
1135 config PROVE_RCU_REPEATEDLY
1136 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1137 depends on PROVE_RCU
1138 default n
1139 help
1140 By itself, PROVE_RCU will disable checking upon issuing the
1141 first warning (or "splat"). This feature prevents such
1142 disabling, allowing multiple RCU-lockdep warnings to be printed
1143 on a single reboot.
1145 Say Y to allow multiple RCU-lockdep warnings per boot.
1147 Say N if you are unsure.
1149 config PROVE_RCU_DELAY
1150 bool "RCU debugging: preemptible RCU race provocation"
1151 depends on DEBUG_KERNEL && PREEMPT_RCU
1152 default n
1153 help
1154 There is a class of races that involve an unlikely preemption
1155 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
1156 been set to INT_MIN. This feature inserts a delay at that
1157 point to increase the probability of these races.
1159 Say Y to increase probability of preemption of __rcu_read_unlock().
1161 Say N if you are unsure.
1163 config SPARSE_RCU_POINTER
1164 bool "RCU debugging: sparse-based checks for pointer usage"
1165 default n
1166 help
1167 This feature enables the __rcu sparse annotation for
1168 RCU-protected pointers. This annotation will cause sparse
1169 to flag any non-RCU used of annotated pointers. This can be
1170 helpful when debugging RCU usage. Please note that this feature
1171 is not intended to enforce code cleanliness; it is instead merely
1172 a debugging aid.
1174 Say Y to make sparse flag questionable use of RCU-protected pointers
1176 Say N if you are unsure.
1178 config TORTURE_TEST
1179 tristate
1180 default n
1182 config RCU_TORTURE_TEST
1183 tristate "torture tests for RCU"
1184 depends on DEBUG_KERNEL
1185 select TORTURE_TEST
1186 default n
1187 help
1188 This option provides a kernel module that runs torture tests
1189 on the RCU infrastructure. The kernel module may be built
1190 after the fact on the running kernel to be tested, if desired.
1192 Say Y here if you want RCU torture tests to be built into
1193 the kernel.
1194 Say M if you want the RCU torture tests to build as a module.
1195 Say N if you are unsure.
1197 config RCU_TORTURE_TEST_RUNNABLE
1198 bool "torture tests for RCU runnable by default"
1199 depends on RCU_TORTURE_TEST = y
1200 default n
1201 help
1202 This option provides a way to build the RCU torture tests
1203 directly into the kernel without them starting up at boot
1204 time. You can use /proc/sys/kernel/rcutorture_runnable
1205 to manually override this setting. This /proc file is
1206 available only when the RCU torture tests have been built
1207 into the kernel.
1209 Say Y here if you want the RCU torture tests to start during
1210 boot (you probably don't).
1211 Say N here if you want the RCU torture tests to start only
1212 after being manually enabled via /proc.
1214 config RCU_CPU_STALL_TIMEOUT
1215 int "RCU CPU stall timeout in seconds"
1216 depends on RCU_STALL_COMMON
1217 range 3 300
1218 default 21
1219 help
1220 If a given RCU grace period extends more than the specified
1221 number of seconds, a CPU stall warning is printed. If the
1222 RCU grace period persists, additional CPU stall warnings are
1223 printed at more widely spaced intervals.
1225 config RCU_CPU_STALL_VERBOSE
1226 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
1227 depends on TREE_PREEMPT_RCU
1228 default y
1229 help
1230 This option causes RCU to printk detailed per-task information
1231 for any tasks that are stalling the current RCU grace period.
1233 Say N if you are unsure.
1235 Say Y if you want to enable such checks.
1237 config RCU_CPU_STALL_INFO
1238 bool "Print additional diagnostics on RCU CPU stall"
1239 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1240 default n
1241 help
1242 For each stalled CPU that is aware of the current RCU grace
1243 period, print out additional per-CPU diagnostic information
1244 regarding scheduling-clock ticks, idle state, and,
1245 for RCU_FAST_NO_HZ kernels, idle-entry state.
1247 Say N if you are unsure.
1249 Say Y if you want to enable such diagnostics.
1251 config RCU_TRACE
1252 bool "Enable tracing for RCU"
1253 depends on DEBUG_KERNEL
1254 select TRACE_CLOCK
1255 help
1256 This option provides tracing in RCU which presents stats
1257 in debugfs for debugging RCU implementation.
1259 Say Y here if you want to enable RCU tracing
1260 Say N if you are unsure.
1262 endmenu # "RCU Debugging"
1264 config DEBUG_BLOCK_EXT_DEVT
1265 bool "Force extended block device numbers and spread them"
1266 depends on DEBUG_KERNEL
1267 depends on BLOCK
1268 default n
1269 help
1270 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1271 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1272 YOU ARE DOING. Distros, please enable this and fix whatever
1273 is broken.
1275 Conventionally, block device numbers are allocated from
1276 predetermined contiguous area. However, extended block area
1277 may introduce non-contiguous block device numbers. This
1278 option forces most block device numbers to be allocated from
1279 the extended space and spreads them to discover kernel or
1280 userland code paths which assume predetermined contiguous
1281 device number allocation.
1283 Note that turning on this debug option shuffles all the
1284 device numbers for all IDE and SCSI devices including libata
1285 ones, so root partition specified using device number
1286 directly (via rdev or root=MAJ:MIN) won't work anymore.
1287 Textual device names (root=/dev/sdXn) will continue to work.
1289 Say N if you are unsure.
1291 config NOTIFIER_ERROR_INJECTION
1292 tristate "Notifier error injection"
1293 depends on DEBUG_KERNEL
1294 select DEBUG_FS
1295 help
1296 This option provides the ability to inject artificial errors to
1297 specified notifier chain callbacks. It is useful to test the error
1298 handling of notifier call chain failures.
1300 Say N if unsure.
1302 config CPU_NOTIFIER_ERROR_INJECT
1303 tristate "CPU notifier error injection module"
1304 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1305 help
1306 This option provides a kernel module that can be used to test
1307 the error handling of the cpu notifiers by injecting artificial
1308 errors to CPU notifier chain callbacks. It is controlled through
1309 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1311 If the notifier call chain should be failed with some events
1312 notified, write the error code to "actions/<notifier event>/error".
1314 Example: Inject CPU offline error (-1 == -EPERM)
1316 # cd /sys/kernel/debug/notifier-error-inject/cpu
1317 # echo -1 > actions/CPU_DOWN_PREPARE/error
1318 # echo 0 > /sys/devices/system/cpu/cpu1/online
1319 bash: echo: write error: Operation not permitted
1321 To compile this code as a module, choose M here: the module will
1322 be called cpu-notifier-error-inject.
1324 If unsure, say N.
1326 config PM_NOTIFIER_ERROR_INJECT
1327 tristate "PM notifier error injection module"
1328 depends on PM && NOTIFIER_ERROR_INJECTION
1329 default m if PM_DEBUG
1330 help
1331 This option provides the ability to inject artificial errors to
1332 PM notifier chain callbacks. It is controlled through debugfs
1333 interface /sys/kernel/debug/notifier-error-inject/pm
1335 If the notifier call chain should be failed with some events
1336 notified, write the error code to "actions/<notifier event>/error".
1338 Example: Inject PM suspend error (-12 = -ENOMEM)
1340 # cd /sys/kernel/debug/notifier-error-inject/pm/
1341 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1342 # echo mem > /sys/power/state
1343 bash: echo: write error: Cannot allocate memory
1345 To compile this code as a module, choose M here: the module will
1346 be called pm-notifier-error-inject.
1348 If unsure, say N.
1350 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1351 tristate "OF reconfig notifier error injection module"
1352 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1353 help
1354 This option provides the ability to inject artificial errors to
1355 OF reconfig notifier chain callbacks. It is controlled
1356 through debugfs interface under
1357 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1359 If the notifier call chain should be failed with some events
1360 notified, write the error code to "actions/<notifier event>/error".
1362 To compile this code as a module, choose M here: the module will
1363 be called of-reconfig-notifier-error-inject.
1365 If unsure, say N.
1367 config FAULT_INJECTION
1368 bool "Fault-injection framework"
1369 depends on DEBUG_KERNEL
1370 help
1371 Provide fault-injection framework.
1372 For more details, see Documentation/fault-injection/.
1374 config FAILSLAB
1375 bool "Fault-injection capability for kmalloc"
1376 depends on FAULT_INJECTION
1377 depends on SLAB || SLUB
1378 help
1379 Provide fault-injection capability for kmalloc.
1381 config FAIL_PAGE_ALLOC
1382 bool "Fault-injection capabilitiy for alloc_pages()"
1383 depends on FAULT_INJECTION
1384 help
1385 Provide fault-injection capability for alloc_pages().
1387 config FAIL_MAKE_REQUEST
1388 bool "Fault-injection capability for disk IO"
1389 depends on FAULT_INJECTION && BLOCK
1390 help
1391 Provide fault-injection capability for disk IO.
1393 config FAIL_IO_TIMEOUT
1394 bool "Fault-injection capability for faking disk interrupts"
1395 depends on FAULT_INJECTION && BLOCK
1396 help
1397 Provide fault-injection capability on end IO handling. This
1398 will make the block layer "forget" an interrupt as configured,
1399 thus exercising the error handling.
1401 Only works with drivers that use the generic timeout handling,
1402 for others it wont do anything.
1404 config FAIL_MMC_REQUEST
1405 bool "Fault-injection capability for MMC IO"
1406 select DEBUG_FS
1407 depends on FAULT_INJECTION && MMC
1408 help
1409 Provide fault-injection capability for MMC IO.
1410 This will make the mmc core return data errors. This is
1411 useful to test the error handling in the mmc block device
1412 and to test how the mmc host driver handles retries from
1413 the block device.
1415 config FAULT_INJECTION_DEBUG_FS
1416 bool "Debugfs entries for fault-injection capabilities"
1417 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1418 help
1419 Enable configuration of fault-injection capabilities via debugfs.
1421 config FAULT_INJECTION_STACKTRACE_FILTER
1422 bool "stacktrace filter for fault-injection capabilities"
1423 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1424 depends on !X86_64
1425 select STACKTRACE
1426 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1427 help
1428 Provide stacktrace filter for fault-injection capabilities
1430 config LATENCYTOP
1431 bool "Latency measuring infrastructure"
1432 depends on HAVE_LATENCYTOP_SUPPORT
1433 depends on DEBUG_KERNEL
1434 depends on STACKTRACE_SUPPORT
1435 depends on PROC_FS
1436 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1437 select KALLSYMS
1438 select KALLSYMS_ALL
1439 select STACKTRACE
1440 select SCHEDSTATS
1441 select SCHED_DEBUG
1442 help
1443 Enable this option if you want to use the LatencyTOP tool
1444 to find out which userspace is blocking on what kernel operations.
1446 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1447 bool
1449 config DEBUG_STRICT_USER_COPY_CHECKS
1450 bool "Strict user copy size checks"
1451 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1452 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1453 help
1454 Enabling this option turns a certain set of sanity checks for user
1455 copy operations into compile time failures.
1457 The copy_from_user() etc checks are there to help test if there
1458 are sufficient security checks on the length argument of
1459 the copy operation, by having gcc prove that the argument is
1460 within bounds.
1462 If unsure, say N.
1464 source kernel/trace/Kconfig
1466 menu "Runtime Testing"
1468 config LKDTM
1469 tristate "Linux Kernel Dump Test Tool Module"
1470 depends on DEBUG_FS
1471 depends on BLOCK
1472 default n
1473 help
1474 This module enables testing of the different dumping mechanisms by
1475 inducing system failures at predefined crash points.
1476 If you don't need it: say N
1477 Choose M here to compile this code as a module. The module will be
1478 called lkdtm.
1480 Documentation on how to use the module can be found in
1481 Documentation/fault-injection/provoke-crashes.txt
1483 config TEST_LIST_SORT
1484 bool "Linked list sorting test"
1485 depends on DEBUG_KERNEL
1486 help
1487 Enable this to turn on 'list_sort()' function test. This test is
1488 executed only once during system boot, so affects only boot time.
1490 If unsure, say N.
1492 config KPROBES_SANITY_TEST
1493 bool "Kprobes sanity tests"
1494 depends on DEBUG_KERNEL
1495 depends on KPROBES
1496 default n
1497 help
1498 This option provides for testing basic kprobes functionality on
1499 boot. A sample kprobe, jprobe and kretprobe are inserted and
1500 verified for functionality.
1502 Say N if you are unsure.
1504 config BACKTRACE_SELF_TEST
1505 tristate "Self test for the backtrace code"
1506 depends on DEBUG_KERNEL
1507 default n
1508 help
1509 This option provides a kernel module that can be used to test
1510 the kernel stack backtrace code. This option is not useful
1511 for distributions or general kernels, but only for kernel
1512 developers working on architecture code.
1514 Note that if you want to also test saved backtraces, you will
1515 have to enable STACKTRACE as well.
1517 Say N if you are unsure.
1519 config RBTREE_TEST
1520 tristate "Red-Black tree test"
1521 depends on DEBUG_KERNEL
1522 help
1523 A benchmark measuring the performance of the rbtree library.
1524 Also includes rbtree invariant checks.
1526 config INTERVAL_TREE_TEST
1527 tristate "Interval tree test"
1528 depends on m && DEBUG_KERNEL
1529 select INTERVAL_TREE
1530 help
1531 A benchmark measuring the performance of the interval tree library
1533 config PERCPU_TEST
1534 tristate "Per cpu operations test"
1535 depends on m && DEBUG_KERNEL
1536 help
1537 Enable this option to build test module which validates per-cpu
1538 operations.
1540 If unsure, say N.
1542 config ATOMIC64_SELFTEST
1543 bool "Perform an atomic64_t self-test at boot"
1544 help
1545 Enable this option to test the atomic64_t functions at boot.
1547 If unsure, say N.
1549 config ASYNC_RAID6_TEST
1550 tristate "Self test for hardware accelerated raid6 recovery"
1551 depends on ASYNC_RAID6_RECOV
1552 select ASYNC_MEMCPY
1553 ---help---
1554 This is a one-shot self test that permutes through the
1555 recovery of all the possible two disk failure scenarios for a
1556 N-disk array. Recovery is performed with the asynchronous
1557 raid6 recovery routines, and will optionally use an offload
1558 engine if one is available.
1560 If unsure, say N.
1562 config TEST_STRING_HELPERS
1563 tristate "Test functions located in the string_helpers module at runtime"
1565 config TEST_KSTRTOX
1566 tristate "Test kstrto*() family of functions at runtime"
1568 endmenu # runtime tests
1570 config PROVIDE_OHCI1394_DMA_INIT
1571 bool "Remote debugging over FireWire early on boot"
1572 depends on PCI && X86
1573 help
1574 If you want to debug problems which hang or crash the kernel early
1575 on boot and the crashing machine has a FireWire port, you can use
1576 this feature to remotely access the memory of the crashed machine
1577 over FireWire. This employs remote DMA as part of the OHCI1394
1578 specification which is now the standard for FireWire controllers.
1580 With remote DMA, you can monitor the printk buffer remotely using
1581 firescope and access all memory below 4GB using fireproxy from gdb.
1582 Even controlling a kernel debugger is possible using remote DMA.
1584 Usage:
1586 If ohci1394_dma=early is used as boot parameter, it will initialize
1587 all OHCI1394 controllers which are found in the PCI config space.
1589 As all changes to the FireWire bus such as enabling and disabling
1590 devices cause a bus reset and thereby disable remote DMA for all
1591 devices, be sure to have the cable plugged and FireWire enabled on
1592 the debugging host before booting the debug target for debugging.
1594 This code (~1k) is freed after boot. By then, the firewire stack
1595 in charge of the OHCI-1394 controllers should be used instead.
1597 See Documentation/debugging-via-ohci1394.txt for more information.
1599 config BUILD_DOCSRC
1600 bool "Build targets in Documentation/ tree"
1601 depends on HEADERS_CHECK
1602 help
1603 This option attempts to build objects from the source files in the
1604 kernel Documentation/ tree.
1606 Say N if you are unsure.
1608 config DMA_API_DEBUG
1609 bool "Enable debugging of DMA-API usage"
1610 depends on HAVE_DMA_API_DEBUG
1611 help
1612 Enable this option to debug the use of the DMA API by device drivers.
1613 With this option you will be able to detect common bugs in device
1614 drivers like double-freeing of DMA mappings or freeing mappings that
1615 were never allocated.
1617 This also attempts to catch cases where a page owned by DMA is
1618 accessed by the cpu in a way that could cause data corruption. For
1619 example, this enables cow_user_page() to check that the source page is
1620 not undergoing DMA.
1622 This option causes a performance degradation. Use only if you want to
1623 debug device drivers and dma interactions.
1625 If unsure, say N.
1627 config TEST_MODULE
1628 tristate "Test module loading with 'hello world' module"
1629 default n
1630 depends on m
1631 help
1632 This builds the "test_module" module that emits "Hello, world"
1633 on printk when loaded. It is designed to be used for basic
1634 evaluation of the module loading subsystem (for example when
1635 validating module verification). It lacks any extra dependencies,
1636 and will not normally be loaded by the system unless explicitly
1637 requested by name.
1639 If unsure, say N.
1641 config TEST_USER_COPY
1642 tristate "Test user/kernel boundary protections"
1643 default n
1644 depends on m
1645 help
1646 This builds the "test_user_copy" module that runs sanity checks
1647 on the copy_to/from_user infrastructure, making sure basic
1648 user/kernel boundary testing is working. If it fails to load,
1649 a regression has been detected in the user/kernel memory boundary
1650 protections.
1652 If unsure, say N.
1654 config TEST_BPF
1655 tristate "Test BPF filter functionality"
1656 default n
1657 depends on m && NET
1658 help
1659 This builds the "test_bpf" module that runs various test vectors
1660 against the BPF interpreter or BPF JIT compiler depending on the
1661 current setting. This is in particular useful for BPF JIT compiler
1662 development, but also to run regression tests against changes in
1663 the interpreter code.
1665 If unsure, say N.
1667 source "samples/Kconfig"
1669 source "lib/Kconfig.kgdb"