1 menu "printk and dmesg options"
4 bool "Show timing information on printks"
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)"
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
29 config BOOT_PRINTK_DELAY
30 bool "Delay each boot printk message by N milliseconds"
31 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
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,
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.
48 bool "Enable dynamic printk() support"
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.
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
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"
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"
121 bool "Compile the kernel with debug info"
122 depends on DEBUG_KERNEL && !COMPILE_TEST
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.
133 config DEBUG_INFO_REDUCED
134 bool "Reduce debugging information"
135 depends on DEBUG_INFO
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
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
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.
171 bool "Provide GDB scripts for kernel debugging"
172 depends on DEBUG_INFO
174 This creates the required links to GDB helper scripts in the
175 build directory. If you load vmlinux into gdb, the helper
176 scripts will be automatically imported by gdb as well, and
177 additional functions are available to analyze a Linux kernel
178 instance. See Documentation/gdb-kernel-debugging.txt for further
181 config ENABLE_WARN_DEPRECATED
182 bool "Enable __deprecated logic"
185 Enable the __deprecated logic in the kernel build.
186 Disable this to suppress the "warning: 'foo' is deprecated
187 (declared at kernel/power/somefile.c:1234)" messages.
189 config ENABLE_MUST_CHECK
190 bool "Enable __must_check logic"
193 Enable the __must_check logic in the kernel build. Disable this to
194 suppress the "warning: ignoring return value of 'foo', declared with
195 attribute warn_unused_result" messages.
198 int "Warn for stack frames larger than (needs gcc 4.4)"
201 default 1024 if !64BIT
202 default 2048 if 64BIT
204 Tell gcc to warn at build time for stack frames larger than this.
205 Setting this too low will cause a lot of warnings.
206 Setting it to 0 disables the warning.
209 config STRIP_ASM_SYMS
210 bool "Strip assembler-generated symbols during link"
213 Strip internal assembler-generated symbols during a link (symbols
214 that look like '.Lxxx') so they don't pollute the output of
215 get_wchan() and suchlike.
218 bool "Generate readable assembler code"
219 depends on DEBUG_KERNEL
221 Disable some compiler optimizations that tend to generate human unreadable
222 assembler output. This may make the kernel slightly slower, but it helps
223 to keep kernel developers who have to stare a lot at assembler listings
226 config UNUSED_SYMBOLS
227 bool "Enable unused/obsolete exported symbols"
230 Unused but exported symbols make the kernel needlessly bigger. For
231 that reason most of these unused exports will soon be removed. This
232 option is provided temporarily to provide a transition period in case
233 some external kernel module needs one of these symbols anyway. If you
234 encounter such a case in your module, consider if you are actually
235 using the right API. (rationale: since nobody in the kernel is using
236 this in a module, there is a pretty good chance it's actually the
237 wrong interface to use). If you really need the symbol, please send a
238 mail to the linux kernel mailing list mentioning the symbol and why
239 you really need it, and what the merge plan to the mainline kernel for
243 bool "Track page owner"
244 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
247 select PAGE_EXTENSION
249 This keeps track of what call chain is the owner of a page, may
250 help to find bare alloc_page(s) leaks. Even if you include this
251 feature on your build, it is disabled in default. You should pass
252 "page_owner=on" to boot parameter in order to enable it. Eats
253 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
254 for user-space helper.
259 bool "Debug Filesystem"
261 debugfs is a virtual file system that kernel developers use to put
262 debugging files into. Enable this option to be able to read and
263 write to these files.
265 For detailed documentation on the debugfs API, see
266 Documentation/DocBook/filesystems.
271 bool "Run 'make headers_check' when building vmlinux"
274 This option will extract the user-visible kernel headers whenever
275 building the kernel, and will run basic sanity checks on them to
276 ensure that exported files do not attempt to include files which
277 were not exported, etc.
279 If you're making modifications to header files which are
280 relevant for userspace, say 'Y', and check the headers
281 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
282 your build tree), to make sure they're suitable.
284 config DEBUG_SECTION_MISMATCH
285 bool "Enable full Section mismatch analysis"
287 The section mismatch analysis checks if there are illegal
288 references from one section to another section.
289 During linktime or runtime, some sections are dropped;
290 any use of code/data previously in these sections would
291 most likely result in an oops.
292 In the code, functions and variables are annotated with
293 __init,, etc. (see the full list in include/linux/init.h),
294 which results in the code/data being placed in specific sections.
295 The section mismatch analysis is always performed after a full
296 kernel build, and enabling this option causes the following
297 additional steps to occur:
298 - Add the option -fno-inline-functions-called-once to gcc commands.
299 When inlining a function annotated with __init in a non-init
300 function, we would lose the section information and thus
301 the analysis would not catch the illegal reference.
302 This option tells gcc to inline less (but it does result in
304 - Run the section mismatch analysis for each module/built-in.o file.
305 When we run the section mismatch analysis on vmlinux.o, we
306 lose valueble information about where the mismatch was
308 Running the analysis for each module/built-in.o file
309 tells where the mismatch happens much closer to the
310 source. The drawback is that the same mismatch is
311 reported at least twice.
312 - Enable verbose reporting from modpost in order to help resolve
313 the section mismatches that are reported.
315 config SECTION_MISMATCH_WARN_ONLY
316 bool "Make section mismatch errors non-fatal"
319 If you say N here, the build process will fail if there are any
320 section mismatch, instead of just throwing warnings.
325 # Select this config option from the architecture Kconfig, if it
326 # is preferred to always offer frame pointers as a config
327 # option on the architecture (regardless of KERNEL_DEBUG):
329 config ARCH_WANT_FRAME_POINTERS
334 bool "Compile the kernel with frame pointers"
335 depends on DEBUG_KERNEL && \
336 (CRIS || M68K || FRV || UML || \
337 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
338 ARCH_WANT_FRAME_POINTERS
339 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
341 If you say Y here the resulting kernel image will be slightly
342 larger and slower, but it gives very useful debugging information
343 in case of kernel bugs. (precise oopses/stacktraces/warnings)
345 config DEBUG_FORCE_WEAK_PER_CPU
346 bool "Force weak per-cpu definitions"
347 depends on DEBUG_KERNEL
349 s390 and alpha require percpu variables in modules to be
350 defined weak to work around addressing range issue which
351 puts the following two restrictions on percpu variable
354 1. percpu symbols must be unique whether static or not
355 2. percpu variables can't be defined inside a function
357 To ensure that generic code follows the above rules, this
358 option forces all percpu variables to be defined as weak.
360 endmenu # "Compiler options"
363 bool "Magic SysRq key"
366 If you say Y here, you will have some control over the system even
367 if the system crashes for example during kernel debugging (e.g., you
368 will be able to flush the buffer cache to disk, reboot the system
369 immediately or dump some status information). This is accomplished
370 by pressing various keys while holding SysRq (Alt+PrintScreen). It
371 also works on a serial console (on PC hardware at least), if you
372 send a BREAK and then within 5 seconds a command keypress. The
373 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
374 unless you really know what this hack does.
376 config MAGIC_SYSRQ_DEFAULT_ENABLE
377 hex "Enable magic SysRq key functions by default"
378 depends on MAGIC_SYSRQ
381 Specifies which SysRq key functions are enabled by default.
382 This may be set to 1 or 0 to enable or disable them all, or
383 to a bitmask as described in Documentation/sysrq.txt.
386 bool "Kernel debugging"
388 Say Y here if you are developing drivers or trying to debug and
389 identify kernel problems.
391 menu "Memory Debugging"
393 source mm/Kconfig.debug
396 bool "Debug object operations"
397 depends on DEBUG_KERNEL
399 If you say Y here, additional code will be inserted into the
400 kernel to track the life time of various objects and validate
401 the operations on those objects.
403 config DEBUG_OBJECTS_SELFTEST
404 bool "Debug objects selftest"
405 depends on DEBUG_OBJECTS
407 This enables the selftest of the object debug code.
409 config DEBUG_OBJECTS_FREE
410 bool "Debug objects in freed memory"
411 depends on DEBUG_OBJECTS
413 This enables checks whether a k/v free operation frees an area
414 which contains an object which has not been deactivated
415 properly. This can make kmalloc/kfree-intensive workloads
418 config DEBUG_OBJECTS_TIMERS
419 bool "Debug timer objects"
420 depends on DEBUG_OBJECTS
422 If you say Y here, additional code will be inserted into the
423 timer routines to track the life time of timer objects and
424 validate the timer operations.
426 config DEBUG_OBJECTS_WORK
427 bool "Debug work objects"
428 depends on DEBUG_OBJECTS
430 If you say Y here, additional code will be inserted into the
431 work queue routines to track the life time of work objects and
432 validate the work operations.
434 config DEBUG_OBJECTS_RCU_HEAD
435 bool "Debug RCU callbacks objects"
436 depends on DEBUG_OBJECTS
438 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
440 config DEBUG_OBJECTS_PERCPU_COUNTER
441 bool "Debug percpu counter objects"
442 depends on DEBUG_OBJECTS
444 If you say Y here, additional code will be inserted into the
445 percpu counter routines to track the life time of percpu counter
446 objects and validate the percpu counter operations.
448 config DEBUG_OBJECTS_ENABLE_DEFAULT
449 int "debug_objects bootup default value (0-1)"
452 depends on DEBUG_OBJECTS
454 Debug objects boot parameter default value
457 bool "Debug slab memory allocations"
458 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
460 Say Y here to have the kernel do limited verification on memory
461 allocation as well as poisoning memory on free to catch use of freed
462 memory. This can make kmalloc/kfree-intensive workloads much slower.
464 config DEBUG_SLAB_LEAK
465 bool "Memory leak debugging"
466 depends on DEBUG_SLAB
469 bool "SLUB debugging on by default"
470 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
473 Boot with debugging on by default. SLUB boots by default with
474 the runtime debug capabilities switched off. Enabling this is
475 equivalent to specifying the "slub_debug" parameter on boot.
476 There is no support for more fine grained debug control like
477 possible with slub_debug=xxx. SLUB debugging may be switched
478 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
483 bool "Enable SLUB performance statistics"
484 depends on SLUB && SYSFS
486 SLUB statistics are useful to debug SLUBs allocation behavior in
487 order find ways to optimize the allocator. This should never be
488 enabled for production use since keeping statistics slows down
489 the allocator by a few percentage points. The slabinfo command
490 supports the determination of the most active slabs to figure
491 out which slabs are relevant to a particular load.
492 Try running: slabinfo -DA
494 config HAVE_DEBUG_KMEMLEAK
497 config DEBUG_KMEMLEAK
498 bool "Kernel memory leak detector"
499 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
501 select STACKTRACE if STACKTRACE_SUPPORT
505 Say Y here if you want to enable the memory leak
506 detector. The memory allocation/freeing is traced in a way
507 similar to the Boehm's conservative garbage collector, the
508 difference being that the orphan objects are not freed but
509 only shown in /sys/kernel/debug/kmemleak. Enabling this
510 feature will introduce an overhead to memory
511 allocations. See Documentation/kmemleak.txt for more
514 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
515 of finding leaks due to the slab objects poisoning.
517 In order to access the kmemleak file, debugfs needs to be
518 mounted (usually at /sys/kernel/debug).
520 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
521 int "Maximum kmemleak early log entries"
522 depends on DEBUG_KMEMLEAK
526 Kmemleak must track all the memory allocations to avoid
527 reporting false positives. Since memory may be allocated or
528 freed before kmemleak is initialised, an early log buffer is
529 used to store these actions. If kmemleak reports "early log
530 buffer exceeded", please increase this value.
532 config DEBUG_KMEMLEAK_TEST
533 tristate "Simple test for the kernel memory leak detector"
534 depends on DEBUG_KMEMLEAK && m
536 This option enables a module that explicitly leaks memory.
540 config DEBUG_KMEMLEAK_DEFAULT_OFF
541 bool "Default kmemleak to off"
542 depends on DEBUG_KMEMLEAK
544 Say Y here to disable kmemleak by default. It can then be enabled
545 on the command line via kmemleak=on.
547 config DEBUG_STACK_USAGE
548 bool "Stack utilization instrumentation"
549 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
551 Enables the display of the minimum amount of free stack which each
552 task has ever had available in the sysrq-T and sysrq-P debug output.
554 This option will slow down process creation somewhat.
558 depends on DEBUG_KERNEL
560 Enable this to turn on extended checks in the virtual-memory system
561 that may impact performance.
565 config DEBUG_VM_VMACACHE
566 bool "Debug VMA caching"
569 Enable this to turn on VMA caching debug information. Doing so
570 can cause significant overhead, so only enable it in non-production
576 bool "Debug VM red-black trees"
579 Enable VM red-black tree debugging information and extra validations.
584 bool "Debug VM translations"
585 depends on DEBUG_KERNEL && X86
587 Enable some costly sanity checks in virtual to page code. This can
588 catch mistakes with virt_to_page() and friends.
592 config DEBUG_NOMMU_REGIONS
593 bool "Debug the global anon/private NOMMU mapping region tree"
594 depends on DEBUG_KERNEL && !MMU
596 This option causes the global tree of anonymous and private mapping
597 regions to be regularly checked for invalid topology.
599 config DEBUG_MEMORY_INIT
600 bool "Debug memory initialisation" if EXPERT
603 Enable this for additional checks during memory initialisation.
604 The sanity checks verify aspects of the VM such as the memory model
605 and other information provided by the architecture. Verbose
606 information will be printed at KERN_DEBUG loglevel depending
607 on the mminit_loglevel= command-line option.
611 config MEMORY_NOTIFIER_ERROR_INJECT
612 tristate "Memory hotplug notifier error injection module"
613 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
615 This option provides the ability to inject artificial errors to
616 memory hotplug notifier chain callbacks. It is controlled through
617 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
619 If the notifier call chain should be failed with some events
620 notified, write the error code to "actions/<notifier event>/error".
622 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
624 # cd /sys/kernel/debug/notifier-error-inject/memory
625 # echo -12 > actions/MEM_GOING_OFFLINE/error
626 # echo offline > /sys/devices/system/memory/memoryXXX/state
627 bash: echo: write error: Cannot allocate memory
629 To compile this code as a module, choose M here: the module will
630 be called memory-notifier-error-inject.
634 config DEBUG_PER_CPU_MAPS
635 bool "Debug access to per_cpu maps"
636 depends on DEBUG_KERNEL
639 Say Y to verify that the per_cpu map being accessed has
640 been set up. This adds a fair amount of code to kernel memory
641 and decreases performance.
646 bool "Highmem debugging"
647 depends on DEBUG_KERNEL && HIGHMEM
649 This option enables additional error checking for high memory
650 systems. Disable for production systems.
652 config HAVE_DEBUG_STACKOVERFLOW
655 config DEBUG_STACKOVERFLOW
656 bool "Check for stack overflows"
657 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
659 Say Y here if you want to check for overflows of kernel, IRQ
660 and exception stacks (if your architecture uses them). This
661 option will show detailed messages if free stack space drops
662 below a certain limit.
664 These kinds of bugs usually occur when call-chains in the
665 kernel get too deep, especially when interrupts are
668 Use this in cases where you see apparently random memory
669 corruption, especially if it appears in 'struct thread_info'
671 If in doubt, say "N".
673 source "lib/Kconfig.kmemcheck"
675 source "lib/Kconfig.kasan"
677 endmenu # "Memory Debugging"
680 bool "Debug shared IRQ handlers"
681 depends on DEBUG_KERNEL
683 Enable this to generate a spurious interrupt as soon as a shared
684 interrupt handler is registered, and just before one is deregistered.
685 Drivers ought to be able to handle interrupts coming in at those
686 points; some don't and need to be caught.
688 menu "Debug Lockups and Hangs"
690 config LOCKUP_DETECTOR
691 bool "Detect Hard and Soft Lockups"
692 depends on DEBUG_KERNEL && !S390
694 Say Y here to enable the kernel to act as a watchdog to detect
695 hard and soft lockups.
697 Softlockups are bugs that cause the kernel to loop in kernel
698 mode for more than 20 seconds, without giving other tasks a
699 chance to run. The current stack trace is displayed upon
700 detection and the system will stay locked up.
702 Hardlockups are bugs that cause the CPU to loop in kernel mode
703 for more than 10 seconds, without letting other interrupts have a
704 chance to run. The current stack trace is displayed upon detection
705 and the system will stay locked up.
707 The overhead should be minimal. A periodic hrtimer runs to
708 generate interrupts and kick the watchdog task every 4 seconds.
709 An NMI is generated every 10 seconds or so to check for hardlockups.
711 The frequency of hrtimer and NMI events and the soft and hard lockup
712 thresholds can be controlled through the sysctl watchdog_thresh.
714 config HARDLOCKUP_DETECTOR
716 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
717 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
719 config BOOTPARAM_HARDLOCKUP_PANIC
720 bool "Panic (Reboot) On Hard Lockups"
721 depends on HARDLOCKUP_DETECTOR
723 Say Y here to enable the kernel to panic on "hard lockups",
724 which are bugs that cause the kernel to loop in kernel
725 mode with interrupts disabled for more than 10 seconds (configurable
726 using the watchdog_thresh sysctl).
730 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
732 depends on HARDLOCKUP_DETECTOR
734 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
735 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
737 config BOOTPARAM_SOFTLOCKUP_PANIC
738 bool "Panic (Reboot) On Soft Lockups"
739 depends on LOCKUP_DETECTOR
741 Say Y here to enable the kernel to panic on "soft lockups",
742 which are bugs that cause the kernel to loop in kernel
743 mode for more than 20 seconds (configurable using the watchdog_thresh
744 sysctl), without giving other tasks a chance to run.
746 The panic can be used in combination with panic_timeout,
747 to cause the system to reboot automatically after a
748 lockup has been detected. This feature is useful for
749 high-availability systems that have uptime guarantees and
750 where a lockup must be resolved ASAP.
754 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
756 depends on LOCKUP_DETECTOR
758 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
759 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
761 config DETECT_HUNG_TASK
762 bool "Detect Hung Tasks"
763 depends on DEBUG_KERNEL
764 default LOCKUP_DETECTOR
766 Say Y here to enable the kernel to detect "hung tasks",
767 which are bugs that cause the task to be stuck in
768 uninterruptible "D" state indefinitiley.
770 When a hung task is detected, the kernel will print the
771 current stack trace (which you should report), but the
772 task will stay in uninterruptible state. If lockdep is
773 enabled then all held locks will also be reported. This
774 feature has negligible overhead.
776 config DEFAULT_HUNG_TASK_TIMEOUT
777 int "Default timeout for hung task detection (in seconds)"
778 depends on DETECT_HUNG_TASK
781 This option controls the default timeout (in seconds) used
782 to determine when a task has become non-responsive and should
785 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
786 sysctl or by writing a value to
787 /proc/sys/kernel/hung_task_timeout_secs.
789 A timeout of 0 disables the check. The default is two minutes.
790 Keeping the default should be fine in most cases.
792 config BOOTPARAM_HUNG_TASK_PANIC
793 bool "Panic (Reboot) On Hung Tasks"
794 depends on DETECT_HUNG_TASK
796 Say Y here to enable the kernel to panic on "hung tasks",
797 which are bugs that cause the kernel to leave a task stuck
798 in uninterruptible "D" state.
800 The panic can be used in combination with panic_timeout,
801 to cause the system to reboot automatically after a
802 hung task has been detected. This feature is useful for
803 high-availability systems that have uptime guarantees and
804 where a hung tasks must be resolved ASAP.
808 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
810 depends on DETECT_HUNG_TASK
812 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
813 default 1 if BOOTPARAM_HUNG_TASK_PANIC
815 endmenu # "Debug lockups and hangs"
820 Say Y here to enable the kernel to panic when it oopses. This
821 has the same effect as setting oops=panic on the kernel command
824 This feature is useful to ensure that the kernel does not do
825 anything erroneous after an oops which could result in data
826 corruption or other issues.
830 config PANIC_ON_OOPS_VALUE
833 default 0 if !PANIC_ON_OOPS
834 default 1 if PANIC_ON_OOPS
840 Set the timeout value (in seconds) until a reboot occurs when the
841 the kernel panics. If n = 0, then we wait forever. A timeout
842 value n > 0 will wait n seconds before rebooting, while a timeout
843 value n < 0 will reboot immediately.
846 bool "Collect scheduler debugging info"
847 depends on DEBUG_KERNEL && PROC_FS
850 If you say Y here, the /proc/sched_debug file will be provided
851 that can help debug the scheduler. The runtime overhead of this
859 bool "Collect scheduler statistics"
860 depends on DEBUG_KERNEL && PROC_FS
863 If you say Y here, additional code will be inserted into the
864 scheduler and related routines to collect statistics about
865 scheduler behavior and provide them in /proc/schedstat. These
866 stats may be useful for both tuning and debugging the scheduler
867 If you aren't debugging the scheduler or trying to tune a specific
868 application, you can say N to avoid the very slight overhead
871 config SCHED_STACK_END_CHECK
872 bool "Detect stack corruption on calls to schedule()"
873 depends on DEBUG_KERNEL
876 This option checks for a stack overrun on calls to schedule().
877 If the stack end location is found to be over written always panic as
878 the content of the corrupted region can no longer be trusted.
879 This is to ensure no erroneous behaviour occurs which could result in
880 data corruption or a sporadic crash at a later stage once the region
881 is examined. The runtime overhead introduced is minimal.
883 config DEBUG_TIMEKEEPING
884 bool "Enable extra timekeeping sanity checking"
886 This option will enable additional timekeeping sanity checks
887 which may be helpful when diagnosing issues where timekeeping
888 problems are suspected.
890 This may include checks in the timekeeping hotpaths, so this
891 option may have a (very small) performance impact to some
897 bool "Collect kernel timers statistics"
898 depends on DEBUG_KERNEL && PROC_FS
900 If you say Y here, additional code will be inserted into the
901 timer routines to collect statistics about kernel timers being
902 reprogrammed. The statistics can be read from /proc/timer_stats.
903 The statistics collection is started by writing 1 to /proc/timer_stats,
904 writing 0 stops it. This feature is useful to collect information
905 about timer usage patterns in kernel and userspace. This feature
906 is lightweight if enabled in the kernel config but not activated
907 (it defaults to deactivated on bootup and will only be activated
908 if some application like powertop activates it explicitly).
911 bool "Debug preemptible kernel"
912 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
915 If you say Y here then the kernel will use a debug variant of the
916 commonly used smp_processor_id() function and will print warnings
917 if kernel code uses it in a preemption-unsafe way. Also, the kernel
918 will detect preemption count underflows.
920 menu "Lock Debugging (spinlocks, mutexes, etc...)"
922 config DEBUG_RT_MUTEXES
923 bool "RT Mutex debugging, deadlock detection"
924 depends on DEBUG_KERNEL && RT_MUTEXES
926 This allows rt mutex semantics violations and rt mutex related
927 deadlocks (lockups) to be detected and reported automatically.
929 config DEBUG_SPINLOCK
930 bool "Spinlock and rw-lock debugging: basic checks"
931 depends on DEBUG_KERNEL
932 select UNINLINE_SPIN_UNLOCK
934 Say Y here and build SMP to catch missing spinlock initialization
935 and certain other kinds of spinlock errors commonly made. This is
936 best used in conjunction with the NMI watchdog so that spinlock
937 deadlocks are also debuggable.
940 bool "Mutex debugging: basic checks"
941 depends on DEBUG_KERNEL
943 This feature allows mutex semantics violations to be detected and
946 config DEBUG_WW_MUTEX_SLOWPATH
947 bool "Wait/wound mutex debugging: Slowpath testing"
948 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
949 select DEBUG_LOCK_ALLOC
950 select DEBUG_SPINLOCK
953 This feature enables slowpath testing for w/w mutex users by
954 injecting additional -EDEADLK wound/backoff cases. Together with
955 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
956 will test all possible w/w mutex interface abuse with the
957 exception of simply not acquiring all the required locks.
958 Note that this feature can introduce significant overhead, so
959 it really should not be enabled in a production or distro kernel,
960 even a debug kernel. If you are a driver writer, enable it. If
961 you are a distro, do not.
963 config DEBUG_LOCK_ALLOC
964 bool "Lock debugging: detect incorrect freeing of live locks"
965 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
966 select DEBUG_SPINLOCK
970 This feature will check whether any held lock (spinlock, rwlock,
971 mutex or rwsem) is incorrectly freed by the kernel, via any of the
972 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
973 vfree(), etc.), whether a live lock is incorrectly reinitialized via
974 spin_lock_init()/mutex_init()/etc., or whether there is any lock
975 held during task exit.
978 bool "Lock debugging: prove locking correctness"
979 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
981 select DEBUG_SPINLOCK
983 select DEBUG_LOCK_ALLOC
984 select TRACE_IRQFLAGS
987 This feature enables the kernel to prove that all locking
988 that occurs in the kernel runtime is mathematically
989 correct: that under no circumstance could an arbitrary (and
990 not yet triggered) combination of observed locking
991 sequences (on an arbitrary number of CPUs, running an
992 arbitrary number of tasks and interrupt contexts) cause a
995 In short, this feature enables the kernel to report locking
996 related deadlocks before they actually occur.
998 The proof does not depend on how hard and complex a
999 deadlock scenario would be to trigger: how many
1000 participant CPUs, tasks and irq-contexts would be needed
1001 for it to trigger. The proof also does not depend on
1002 timing: if a race and a resulting deadlock is possible
1003 theoretically (no matter how unlikely the race scenario
1004 is), it will be proven so and will immediately be
1005 reported by the kernel (once the event is observed that
1006 makes the deadlock theoretically possible).
1008 If a deadlock is impossible (i.e. the locking rules, as
1009 observed by the kernel, are mathematically correct), the
1010 kernel reports nothing.
1012 NOTE: this feature can also be enabled for rwlocks, mutexes
1013 and rwsems - in which case all dependencies between these
1014 different locking variants are observed and mapped too, and
1015 the proof of observed correctness is also maintained for an
1016 arbitrary combination of these separate locking variants.
1018 For more details, see Documentation/locking/lockdep-design.txt.
1022 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1024 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
1029 bool "Lock usage statistics"
1030 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1032 select DEBUG_SPINLOCK
1033 select DEBUG_MUTEXES
1034 select DEBUG_LOCK_ALLOC
1037 This feature enables tracking lock contention points
1039 For more details, see Documentation/locking/lockstat.txt
1041 This also enables lock events required by "perf lock",
1043 If you want to use "perf lock", you also need to turn on
1044 CONFIG_EVENT_TRACING.
1046 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1047 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1049 config DEBUG_LOCKDEP
1050 bool "Lock dependency engine debugging"
1051 depends on DEBUG_KERNEL && LOCKDEP
1053 If you say Y here, the lock dependency engine will do
1054 additional runtime checks to debug itself, at the price
1055 of more runtime overhead.
1057 config DEBUG_ATOMIC_SLEEP
1058 bool "Sleep inside atomic section checking"
1059 select PREEMPT_COUNT
1060 depends on DEBUG_KERNEL
1062 If you say Y here, various routines which may sleep will become very
1063 noisy if they are called inside atomic sections: when a spinlock is
1064 held, inside an rcu read side critical section, inside preempt disabled
1065 sections, inside an interrupt, etc...
1067 config DEBUG_LOCKING_API_SELFTESTS
1068 bool "Locking API boot-time self-tests"
1069 depends on DEBUG_KERNEL
1071 Say Y here if you want the kernel to run a short self-test during
1072 bootup. The self-test checks whether common types of locking bugs
1073 are detected by debugging mechanisms or not. (if you disable
1074 lock debugging then those bugs wont be detected of course.)
1075 The following locking APIs are covered: spinlocks, rwlocks,
1078 config LOCK_TORTURE_TEST
1079 tristate "torture tests for locking"
1080 depends on DEBUG_KERNEL
1084 This option provides a kernel module that runs torture tests
1085 on kernel locking primitives. The kernel module may be built
1086 after the fact on the running kernel to be tested, if desired.
1088 Say Y here if you want kernel locking-primitive torture tests
1089 to be built into the kernel.
1090 Say M if you want these torture tests to build as a module.
1091 Say N if you are unsure.
1093 endmenu # lock debugging
1095 config TRACE_IRQFLAGS
1098 Enables hooks to interrupt enabling and disabling for
1099 either tracing or lock debugging.
1102 bool "Stack backtrace support"
1103 depends on STACKTRACE_SUPPORT
1105 This option causes the kernel to create a /proc/pid/stack for
1106 every process, showing its current stack trace.
1107 It is also used by various kernel debugging features that require
1108 stack trace generation.
1110 config DEBUG_KOBJECT
1111 bool "kobject debugging"
1112 depends on DEBUG_KERNEL
1114 If you say Y here, some extra kobject debugging messages will be sent
1117 config DEBUG_KOBJECT_RELEASE
1118 bool "kobject release debugging"
1119 depends on DEBUG_OBJECTS_TIMERS
1121 kobjects are reference counted objects. This means that their
1122 last reference count put is not predictable, and the kobject can
1123 live on past the point at which a driver decides to drop it's
1124 initial reference to the kobject gained on allocation. An
1125 example of this would be a struct device which has just been
1128 However, some buggy drivers assume that after such an operation,
1129 the memory backing the kobject can be immediately freed. This
1130 goes completely against the principles of a refcounted object.
1132 If you say Y here, the kernel will delay the release of kobjects
1133 on the last reference count to improve the visibility of this
1134 kind of kobject release bug.
1136 config HAVE_DEBUG_BUGVERBOSE
1139 config DEBUG_BUGVERBOSE
1140 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1141 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1144 Say Y here to make BUG() panics output the file name and line number
1145 of the BUG call as well as the EIP and oops trace. This aids
1146 debugging but costs about 70-100K of memory.
1149 bool "Debug linked list manipulation"
1150 depends on DEBUG_KERNEL
1152 Enable this to turn on extended checks in the linked-list
1157 config DEBUG_PI_LIST
1158 bool "Debug priority linked list manipulation"
1159 depends on DEBUG_KERNEL
1161 Enable this to turn on extended checks in the priority-ordered
1162 linked-list (plist) walking routines. This checks the entire
1163 list multiple times during each manipulation.
1168 bool "Debug SG table operations"
1169 depends on DEBUG_KERNEL
1171 Enable this to turn on checks on scatter-gather tables. This can
1172 help find problems with drivers that do not properly initialize
1177 config DEBUG_NOTIFIERS
1178 bool "Debug notifier call chains"
1179 depends on DEBUG_KERNEL
1181 Enable this to turn on sanity checking for notifier call chains.
1182 This is most useful for kernel developers to make sure that
1183 modules properly unregister themselves from notifier chains.
1184 This is a relatively cheap check but if you care about maximum
1187 config DEBUG_CREDENTIALS
1188 bool "Debug credential management"
1189 depends on DEBUG_KERNEL
1191 Enable this to turn on some debug checking for credential
1192 management. The additional code keeps track of the number of
1193 pointers from task_structs to any given cred struct, and checks to
1194 see that this number never exceeds the usage count of the cred
1197 Furthermore, if SELinux is enabled, this also checks that the
1198 security pointer in the cred struct is never seen to be invalid.
1202 menu "RCU Debugging"
1205 def_bool PROVE_LOCKING
1207 config PROVE_RCU_REPEATEDLY
1208 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1209 depends on PROVE_RCU
1212 By itself, PROVE_RCU will disable checking upon issuing the
1213 first warning (or "splat"). This feature prevents such
1214 disabling, allowing multiple RCU-lockdep warnings to be printed
1217 Say Y to allow multiple RCU-lockdep warnings per boot.
1219 Say N if you are unsure.
1221 config SPARSE_RCU_POINTER
1222 bool "RCU debugging: sparse-based checks for pointer usage"
1225 This feature enables the __rcu sparse annotation for
1226 RCU-protected pointers. This annotation will cause sparse
1227 to flag any non-RCU used of annotated pointers. This can be
1228 helpful when debugging RCU usage. Please note that this feature
1229 is not intended to enforce code cleanliness; it is instead merely
1232 Say Y to make sparse flag questionable use of RCU-protected pointers
1234 Say N if you are unsure.
1240 config RCU_TORTURE_TEST
1241 tristate "torture tests for RCU"
1242 depends on DEBUG_KERNEL
1248 This option provides a kernel module that runs torture tests
1249 on the RCU infrastructure. The kernel module may be built
1250 after the fact on the running kernel to be tested, if desired.
1252 Say Y here if you want RCU torture tests to be built into
1254 Say M if you want the RCU torture tests to build as a module.
1255 Say N if you are unsure.
1257 config RCU_TORTURE_TEST_RUNNABLE
1258 bool "torture tests for RCU runnable by default"
1259 depends on RCU_TORTURE_TEST = y
1262 This option provides a way to build the RCU torture tests
1263 directly into the kernel without them starting up at boot
1264 time. You can use /proc/sys/kernel/rcutorture_runnable
1265 to manually override this setting. This /proc file is
1266 available only when the RCU torture tests have been built
1269 Say Y here if you want the RCU torture tests to start during
1270 boot (you probably don't).
1271 Say N here if you want the RCU torture tests to start only
1272 after being manually enabled via /proc.
1274 config RCU_TORTURE_TEST_SLOW_PREINIT
1275 bool "Slow down RCU grace-period pre-initialization to expose races"
1276 depends on RCU_TORTURE_TEST
1278 This option delays grace-period pre-initialization (the
1279 propagation of CPU-hotplug changes up the rcu_node combining
1280 tree) for a few jiffies between initializing each pair of
1281 consecutive rcu_node structures. This helps to expose races
1282 involving grace-period pre-initialization, in other words, it
1283 makes your kernel less stable. It can also greatly increase
1284 grace-period latency, especially on systems with large numbers
1285 of CPUs. This is useful when torture-testing RCU, but in
1286 almost no other circumstance.
1288 Say Y here if you want your system to crash and hang more often.
1289 Say N if you want a sane system.
1291 config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1292 int "How much to slow down RCU grace-period pre-initialization"
1295 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1297 This option specifies the number of jiffies to wait between
1298 each rcu_node structure pre-initialization step.
1300 config RCU_TORTURE_TEST_SLOW_INIT
1301 bool "Slow down RCU grace-period initialization to expose races"
1302 depends on RCU_TORTURE_TEST
1304 This option delays grace-period initialization for a few
1305 jiffies between initializing each pair of consecutive
1306 rcu_node structures. This helps to expose races involving
1307 grace-period initialization, in other words, it makes your
1308 kernel less stable. It can also greatly increase grace-period
1309 latency, especially on systems with large numbers of CPUs.
1310 This is useful when torture-testing RCU, but in almost no
1313 Say Y here if you want your system to crash and hang more often.
1314 Say N if you want a sane system.
1316 config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1317 int "How much to slow down RCU grace-period initialization"
1320 depends on RCU_TORTURE_TEST_SLOW_INIT
1322 This option specifies the number of jiffies to wait between
1323 each rcu_node structure initialization.
1325 config RCU_TORTURE_TEST_SLOW_CLEANUP
1326 bool "Slow down RCU grace-period cleanup to expose races"
1327 depends on RCU_TORTURE_TEST
1329 This option delays grace-period cleanup for a few jiffies
1330 between cleaning up each pair of consecutive rcu_node
1331 structures. This helps to expose races involving grace-period
1332 cleanup, in other words, it makes your kernel less stable.
1333 It can also greatly increase grace-period latency, especially
1334 on systems with large numbers of CPUs. This is useful when
1335 torture-testing RCU, but in almost no other circumstance.
1337 Say Y here if you want your system to crash and hang more often.
1338 Say N if you want a sane system.
1340 config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1341 int "How much to slow down RCU grace-period cleanup"
1344 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1346 This option specifies the number of jiffies to wait between
1347 each rcu_node structure cleanup operation.
1349 config RCU_CPU_STALL_TIMEOUT
1350 int "RCU CPU stall timeout in seconds"
1351 depends on RCU_STALL_COMMON
1355 If a given RCU grace period extends more than the specified
1356 number of seconds, a CPU stall warning is printed. If the
1357 RCU grace period persists, additional CPU stall warnings are
1358 printed at more widely spaced intervals.
1361 bool "Enable tracing for RCU"
1362 depends on DEBUG_KERNEL
1365 This option provides tracing in RCU which presents stats
1366 in debugfs for debugging RCU implementation.
1368 Say Y here if you want to enable RCU tracing
1369 Say N if you are unsure.
1371 config RCU_EQS_DEBUG
1372 bool "Provide debugging asserts for adding NO_HZ support to an arch"
1373 depends on DEBUG_KERNEL
1375 This option provides consistency checks in RCU's handling of
1376 NO_HZ. These checks have proven quite helpful in detecting
1377 bugs in arch-specific NO_HZ code.
1379 Say N here if you need ultimate kernel/user switch latencies
1380 Say Y if you are unsure
1382 endmenu # "RCU Debugging"
1384 config DEBUG_BLOCK_EXT_DEVT
1385 bool "Force extended block device numbers and spread them"
1386 depends on DEBUG_KERNEL
1390 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1391 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1392 YOU ARE DOING. Distros, please enable this and fix whatever
1395 Conventionally, block device numbers are allocated from
1396 predetermined contiguous area. However, extended block area
1397 may introduce non-contiguous block device numbers. This
1398 option forces most block device numbers to be allocated from
1399 the extended space and spreads them to discover kernel or
1400 userland code paths which assume predetermined contiguous
1401 device number allocation.
1403 Note that turning on this debug option shuffles all the
1404 device numbers for all IDE and SCSI devices including libata
1405 ones, so root partition specified using device number
1406 directly (via rdev or root=MAJ:MIN) won't work anymore.
1407 Textual device names (root=/dev/sdXn) will continue to work.
1409 Say N if you are unsure.
1411 config NOTIFIER_ERROR_INJECTION
1412 tristate "Notifier error injection"
1413 depends on DEBUG_KERNEL
1416 This option provides the ability to inject artificial errors to
1417 specified notifier chain callbacks. It is useful to test the error
1418 handling of notifier call chain failures.
1422 config CPU_NOTIFIER_ERROR_INJECT
1423 tristate "CPU notifier error injection module"
1424 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1426 This option provides a kernel module that can be used to test
1427 the error handling of the cpu notifiers by injecting artificial
1428 errors to CPU notifier chain callbacks. It is controlled through
1429 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1431 If the notifier call chain should be failed with some events
1432 notified, write the error code to "actions/<notifier event>/error".
1434 Example: Inject CPU offline error (-1 == -EPERM)
1436 # cd /sys/kernel/debug/notifier-error-inject/cpu
1437 # echo -1 > actions/CPU_DOWN_PREPARE/error
1438 # echo 0 > /sys/devices/system/cpu/cpu1/online
1439 bash: echo: write error: Operation not permitted
1441 To compile this code as a module, choose M here: the module will
1442 be called cpu-notifier-error-inject.
1446 config PM_NOTIFIER_ERROR_INJECT
1447 tristate "PM notifier error injection module"
1448 depends on PM && NOTIFIER_ERROR_INJECTION
1449 default m if PM_DEBUG
1451 This option provides the ability to inject artificial errors to
1452 PM notifier chain callbacks. It is controlled through debugfs
1453 interface /sys/kernel/debug/notifier-error-inject/pm
1455 If the notifier call chain should be failed with some events
1456 notified, write the error code to "actions/<notifier event>/error".
1458 Example: Inject PM suspend error (-12 = -ENOMEM)
1460 # cd /sys/kernel/debug/notifier-error-inject/pm/
1461 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1462 # echo mem > /sys/power/state
1463 bash: echo: write error: Cannot allocate memory
1465 To compile this code as a module, choose M here: the module will
1466 be called pm-notifier-error-inject.
1470 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1471 tristate "OF reconfig notifier error injection module"
1472 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1474 This option provides the ability to inject artificial errors to
1475 OF reconfig notifier chain callbacks. It is controlled
1476 through debugfs interface under
1477 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1479 If the notifier call chain should be failed with some events
1480 notified, write the error code to "actions/<notifier event>/error".
1482 To compile this code as a module, choose M here: the module will
1483 be called of-reconfig-notifier-error-inject.
1487 config FAULT_INJECTION
1488 bool "Fault-injection framework"
1489 depends on DEBUG_KERNEL
1491 Provide fault-injection framework.
1492 For more details, see Documentation/fault-injection/.
1495 bool "Fault-injection capability for kmalloc"
1496 depends on FAULT_INJECTION
1497 depends on SLAB || SLUB
1499 Provide fault-injection capability for kmalloc.
1501 config FAIL_PAGE_ALLOC
1502 bool "Fault-injection capabilitiy for alloc_pages()"
1503 depends on FAULT_INJECTION
1505 Provide fault-injection capability for alloc_pages().
1507 config FAIL_MAKE_REQUEST
1508 bool "Fault-injection capability for disk IO"
1509 depends on FAULT_INJECTION && BLOCK
1511 Provide fault-injection capability for disk IO.
1513 config FAIL_IO_TIMEOUT
1514 bool "Fault-injection capability for faking disk interrupts"
1515 depends on FAULT_INJECTION && BLOCK
1517 Provide fault-injection capability on end IO handling. This
1518 will make the block layer "forget" an interrupt as configured,
1519 thus exercising the error handling.
1521 Only works with drivers that use the generic timeout handling,
1522 for others it wont do anything.
1524 config FAIL_MMC_REQUEST
1525 bool "Fault-injection capability for MMC IO"
1527 depends on FAULT_INJECTION && MMC
1529 Provide fault-injection capability for MMC IO.
1530 This will make the mmc core return data errors. This is
1531 useful to test the error handling in the mmc block device
1532 and to test how the mmc host driver handles retries from
1536 bool "Fault-injection capability for futexes"
1538 depends on FAULT_INJECTION && FUTEX
1540 Provide fault-injection capability for futexes.
1542 config FAULT_INJECTION_DEBUG_FS
1543 bool "Debugfs entries for fault-injection capabilities"
1544 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1546 Enable configuration of fault-injection capabilities via debugfs.
1548 config FAULT_INJECTION_STACKTRACE_FILTER
1549 bool "stacktrace filter for fault-injection capabilities"
1550 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1553 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1555 Provide stacktrace filter for fault-injection capabilities
1558 bool "Latency measuring infrastructure"
1559 depends on HAVE_LATENCYTOP_SUPPORT
1560 depends on DEBUG_KERNEL
1561 depends on STACKTRACE_SUPPORT
1563 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1570 Enable this option if you want to use the LatencyTOP tool
1571 to find out which userspace is blocking on what kernel operations.
1573 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1576 config DEBUG_STRICT_USER_COPY_CHECKS
1577 bool "Strict user copy size checks"
1578 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1579 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1581 Enabling this option turns a certain set of sanity checks for user
1582 copy operations into compile time failures.
1584 The copy_from_user() etc checks are there to help test if there
1585 are sufficient security checks on the length argument of
1586 the copy operation, by having gcc prove that the argument is
1591 source kernel/trace/Kconfig
1593 menu "Runtime Testing"
1596 tristate "Linux Kernel Dump Test Tool Module"
1601 This module enables testing of the different dumping mechanisms by
1602 inducing system failures at predefined crash points.
1603 If you don't need it: say N
1604 Choose M here to compile this code as a module. The module will be
1607 Documentation on how to use the module can be found in
1608 Documentation/fault-injection/provoke-crashes.txt
1610 config TEST_LIST_SORT
1611 bool "Linked list sorting test"
1612 depends on DEBUG_KERNEL
1614 Enable this to turn on 'list_sort()' function test. This test is
1615 executed only once during system boot, so affects only boot time.
1619 config KPROBES_SANITY_TEST
1620 bool "Kprobes sanity tests"
1621 depends on DEBUG_KERNEL
1625 This option provides for testing basic kprobes functionality on
1626 boot. A sample kprobe, jprobe and kretprobe are inserted and
1627 verified for functionality.
1629 Say N if you are unsure.
1631 config BACKTRACE_SELF_TEST
1632 tristate "Self test for the backtrace code"
1633 depends on DEBUG_KERNEL
1636 This option provides a kernel module that can be used to test
1637 the kernel stack backtrace code. This option is not useful
1638 for distributions or general kernels, but only for kernel
1639 developers working on architecture code.
1641 Note that if you want to also test saved backtraces, you will
1642 have to enable STACKTRACE as well.
1644 Say N if you are unsure.
1647 tristate "Red-Black tree test"
1648 depends on DEBUG_KERNEL
1650 A benchmark measuring the performance of the rbtree library.
1651 Also includes rbtree invariant checks.
1653 config INTERVAL_TREE_TEST
1654 tristate "Interval tree test"
1655 depends on m && DEBUG_KERNEL
1656 select INTERVAL_TREE
1658 A benchmark measuring the performance of the interval tree library
1661 tristate "Per cpu operations test"
1662 depends on m && DEBUG_KERNEL
1664 Enable this option to build test module which validates per-cpu
1669 config ATOMIC64_SELFTEST
1670 bool "Perform an atomic64_t self-test at boot"
1672 Enable this option to test the atomic64_t functions at boot.
1676 config ASYNC_RAID6_TEST
1677 tristate "Self test for hardware accelerated raid6 recovery"
1678 depends on ASYNC_RAID6_RECOV
1681 This is a one-shot self test that permutes through the
1682 recovery of all the possible two disk failure scenarios for a
1683 N-disk array. Recovery is performed with the asynchronous
1684 raid6 recovery routines, and will optionally use an offload
1685 engine if one is available.
1690 tristate "Test functions located in the hexdump module at runtime"
1692 config TEST_STRING_HELPERS
1693 tristate "Test functions located in the string_helpers module at runtime"
1696 tristate "Test kstrto*() family of functions at runtime"
1699 tristate "Test printf() family of functions at runtime"
1701 config TEST_RHASHTABLE
1702 tristate "Perform selftest on resizable hash table"
1705 Enable this option to test the rhashtable functions at boot.
1709 endmenu # runtime tests
1711 config PROVIDE_OHCI1394_DMA_INIT
1712 bool "Remote debugging over FireWire early on boot"
1713 depends on PCI && X86
1715 If you want to debug problems which hang or crash the kernel early
1716 on boot and the crashing machine has a FireWire port, you can use
1717 this feature to remotely access the memory of the crashed machine
1718 over FireWire. This employs remote DMA as part of the OHCI1394
1719 specification which is now the standard for FireWire controllers.
1721 With remote DMA, you can monitor the printk buffer remotely using
1722 firescope and access all memory below 4GB using fireproxy from gdb.
1723 Even controlling a kernel debugger is possible using remote DMA.
1727 If ohci1394_dma=early is used as boot parameter, it will initialize
1728 all OHCI1394 controllers which are found in the PCI config space.
1730 As all changes to the FireWire bus such as enabling and disabling
1731 devices cause a bus reset and thereby disable remote DMA for all
1732 devices, be sure to have the cable plugged and FireWire enabled on
1733 the debugging host before booting the debug target for debugging.
1735 This code (~1k) is freed after boot. By then, the firewire stack
1736 in charge of the OHCI-1394 controllers should be used instead.
1738 See Documentation/debugging-via-ohci1394.txt for more information.
1741 bool "Build targets in Documentation/ tree"
1742 depends on HEADERS_CHECK
1744 This option attempts to build objects from the source files in the
1745 kernel Documentation/ tree.
1747 Say N if you are unsure.
1749 config DMA_API_DEBUG
1750 bool "Enable debugging of DMA-API usage"
1751 depends on HAVE_DMA_API_DEBUG
1753 Enable this option to debug the use of the DMA API by device drivers.
1754 With this option you will be able to detect common bugs in device
1755 drivers like double-freeing of DMA mappings or freeing mappings that
1756 were never allocated.
1758 This also attempts to catch cases where a page owned by DMA is
1759 accessed by the cpu in a way that could cause data corruption. For
1760 example, this enables cow_user_page() to check that the source page is
1763 This option causes a performance degradation. Use only if you want to
1764 debug device drivers and dma interactions.
1769 tristate "Test module loading with 'hello world' module"
1773 This builds the "test_module" module that emits "Hello, world"
1774 on printk when loaded. It is designed to be used for basic
1775 evaluation of the module loading subsystem (for example when
1776 validating module verification). It lacks any extra dependencies,
1777 and will not normally be loaded by the system unless explicitly
1782 config TEST_USER_COPY
1783 tristate "Test user/kernel boundary protections"
1787 This builds the "test_user_copy" module that runs sanity checks
1788 on the copy_to/from_user infrastructure, making sure basic
1789 user/kernel boundary testing is working. If it fails to load,
1790 a regression has been detected in the user/kernel memory boundary
1796 tristate "Test BPF filter functionality"
1800 This builds the "test_bpf" module that runs various test vectors
1801 against the BPF interpreter or BPF JIT compiler depending on the
1802 current setting. This is in particular useful for BPF JIT compiler
1803 development, but also to run regression tests against changes in
1804 the interpreter code. It also enables test stubs for eBPF maps and
1805 verifier used by user space verifier testsuite.
1809 config TEST_FIRMWARE
1810 tristate "Test firmware loading via userspace interface"
1812 depends on FW_LOADER
1814 This builds the "test_firmware" module that creates a userspace
1815 interface for testing firmware loading. This can be used to
1816 control the triggering of firmware loading without needing an
1817 actual firmware-using device. The contents can be rechecked by
1823 tristate "udelay test driver"
1826 This builds the "udelay_test" module that helps to make sure
1827 that udelay() is working properly.
1833 depends on HAVE_MEMBLOCK
1835 This option adds a kernel parameter 'memtest', which allows memtest
1837 memtest=0, mean disabled; -- default
1838 memtest=1, mean do 1 test pattern;
1840 memtest=17, mean do 17 test patterns.
1841 If you are unsure how to answer this question, answer N.
1843 config TEST_STATIC_KEYS
1844 tristate "Test static keys"
1848 Test the static key interfaces.
1852 source "samples/Kconfig"
1854 source "lib/Kconfig.kgdb"
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