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.
316 # Select this config option from the architecture Kconfig, if it
317 # is preferred to always offer frame pointers as a config
318 # option on the architecture (regardless of KERNEL_DEBUG):
320 config ARCH_WANT_FRAME_POINTERS
325 bool "Compile the kernel with frame pointers"
326 depends on DEBUG_KERNEL && \
327 (CRIS || M68K || FRV || UML || \
328 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
329 ARCH_WANT_FRAME_POINTERS
330 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
332 If you say Y here the resulting kernel image will be slightly
333 larger and slower, but it gives very useful debugging information
334 in case of kernel bugs. (precise oopses/stacktraces/warnings)
336 config DEBUG_FORCE_WEAK_PER_CPU
337 bool "Force weak per-cpu definitions"
338 depends on DEBUG_KERNEL
340 s390 and alpha require percpu variables in modules to be
341 defined weak to work around addressing range issue which
342 puts the following two restrictions on percpu variable
345 1. percpu symbols must be unique whether static or not
346 2. percpu variables can't be defined inside a function
348 To ensure that generic code follows the above rules, this
349 option forces all percpu variables to be defined as weak.
351 endmenu # "Compiler options"
354 bool "Magic SysRq key"
357 If you say Y here, you will have some control over the system even
358 if the system crashes for example during kernel debugging (e.g., you
359 will be able to flush the buffer cache to disk, reboot the system
360 immediately or dump some status information). This is accomplished
361 by pressing various keys while holding SysRq (Alt+PrintScreen). It
362 also works on a serial console (on PC hardware at least), if you
363 send a BREAK and then within 5 seconds a command keypress. The
364 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
365 unless you really know what this hack does.
367 config MAGIC_SYSRQ_DEFAULT_ENABLE
368 hex "Enable magic SysRq key functions by default"
369 depends on MAGIC_SYSRQ
372 Specifies which SysRq key functions are enabled by default.
373 This may be set to 1 or 0 to enable or disable them all, or
374 to a bitmask as described in Documentation/sysrq.txt.
377 bool "Kernel debugging"
379 Say Y here if you are developing drivers or trying to debug and
380 identify kernel problems.
382 menu "Memory Debugging"
384 source mm/Kconfig.debug
387 bool "Debug object operations"
388 depends on DEBUG_KERNEL
390 If you say Y here, additional code will be inserted into the
391 kernel to track the life time of various objects and validate
392 the operations on those objects.
394 config DEBUG_OBJECTS_SELFTEST
395 bool "Debug objects selftest"
396 depends on DEBUG_OBJECTS
398 This enables the selftest of the object debug code.
400 config DEBUG_OBJECTS_FREE
401 bool "Debug objects in freed memory"
402 depends on DEBUG_OBJECTS
404 This enables checks whether a k/v free operation frees an area
405 which contains an object which has not been deactivated
406 properly. This can make kmalloc/kfree-intensive workloads
409 config DEBUG_OBJECTS_TIMERS
410 bool "Debug timer objects"
411 depends on DEBUG_OBJECTS
413 If you say Y here, additional code will be inserted into the
414 timer routines to track the life time of timer objects and
415 validate the timer operations.
417 config DEBUG_OBJECTS_WORK
418 bool "Debug work objects"
419 depends on DEBUG_OBJECTS
421 If you say Y here, additional code will be inserted into the
422 work queue routines to track the life time of work objects and
423 validate the work operations.
425 config DEBUG_OBJECTS_RCU_HEAD
426 bool "Debug RCU callbacks objects"
427 depends on DEBUG_OBJECTS
429 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
431 config DEBUG_OBJECTS_PERCPU_COUNTER
432 bool "Debug percpu counter objects"
433 depends on DEBUG_OBJECTS
435 If you say Y here, additional code will be inserted into the
436 percpu counter routines to track the life time of percpu counter
437 objects and validate the percpu counter operations.
439 config DEBUG_OBJECTS_ENABLE_DEFAULT
440 int "debug_objects bootup default value (0-1)"
443 depends on DEBUG_OBJECTS
445 Debug objects boot parameter default value
448 bool "Debug slab memory allocations"
449 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
451 Say Y here to have the kernel do limited verification on memory
452 allocation as well as poisoning memory on free to catch use of freed
453 memory. This can make kmalloc/kfree-intensive workloads much slower.
455 config DEBUG_SLAB_LEAK
456 bool "Memory leak debugging"
457 depends on DEBUG_SLAB
460 bool "SLUB debugging on by default"
461 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
464 Boot with debugging on by default. SLUB boots by default with
465 the runtime debug capabilities switched off. Enabling this is
466 equivalent to specifying the "slub_debug" parameter on boot.
467 There is no support for more fine grained debug control like
468 possible with slub_debug=xxx. SLUB debugging may be switched
469 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
474 bool "Enable SLUB performance statistics"
475 depends on SLUB && SYSFS
477 SLUB statistics are useful to debug SLUBs allocation behavior in
478 order find ways to optimize the allocator. This should never be
479 enabled for production use since keeping statistics slows down
480 the allocator by a few percentage points. The slabinfo command
481 supports the determination of the most active slabs to figure
482 out which slabs are relevant to a particular load.
483 Try running: slabinfo -DA
485 config HAVE_DEBUG_KMEMLEAK
488 config DEBUG_KMEMLEAK
489 bool "Kernel memory leak detector"
490 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
492 select STACKTRACE if STACKTRACE_SUPPORT
496 Say Y here if you want to enable the memory leak
497 detector. The memory allocation/freeing is traced in a way
498 similar to the Boehm's conservative garbage collector, the
499 difference being that the orphan objects are not freed but
500 only shown in /sys/kernel/debug/kmemleak. Enabling this
501 feature will introduce an overhead to memory
502 allocations. See Documentation/kmemleak.txt for more
505 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
506 of finding leaks due to the slab objects poisoning.
508 In order to access the kmemleak file, debugfs needs to be
509 mounted (usually at /sys/kernel/debug).
511 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
512 int "Maximum kmemleak early log entries"
513 depends on DEBUG_KMEMLEAK
517 Kmemleak must track all the memory allocations to avoid
518 reporting false positives. Since memory may be allocated or
519 freed before kmemleak is initialised, an early log buffer is
520 used to store these actions. If kmemleak reports "early log
521 buffer exceeded", please increase this value.
523 config DEBUG_KMEMLEAK_TEST
524 tristate "Simple test for the kernel memory leak detector"
525 depends on DEBUG_KMEMLEAK && m
527 This option enables a module that explicitly leaks memory.
531 config DEBUG_KMEMLEAK_DEFAULT_OFF
532 bool "Default kmemleak to off"
533 depends on DEBUG_KMEMLEAK
535 Say Y here to disable kmemleak by default. It can then be enabled
536 on the command line via kmemleak=on.
538 config DEBUG_STACK_USAGE
539 bool "Stack utilization instrumentation"
540 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
542 Enables the display of the minimum amount of free stack which each
543 task has ever had available in the sysrq-T and sysrq-P debug output.
545 This option will slow down process creation somewhat.
549 depends on DEBUG_KERNEL
551 Enable this to turn on extended checks in the virtual-memory system
552 that may impact performance.
556 config DEBUG_VM_VMACACHE
557 bool "Debug VMA caching"
560 Enable this to turn on VMA caching debug information. Doing so
561 can cause significant overhead, so only enable it in non-production
567 bool "Debug VM red-black trees"
570 Enable VM red-black tree debugging information and extra validations.
575 bool "Debug VM translations"
576 depends on DEBUG_KERNEL && X86
578 Enable some costly sanity checks in virtual to page code. This can
579 catch mistakes with virt_to_page() and friends.
583 config DEBUG_NOMMU_REGIONS
584 bool "Debug the global anon/private NOMMU mapping region tree"
585 depends on DEBUG_KERNEL && !MMU
587 This option causes the global tree of anonymous and private mapping
588 regions to be regularly checked for invalid topology.
590 config DEBUG_MEMORY_INIT
591 bool "Debug memory initialisation" if EXPERT
594 Enable this for additional checks during memory initialisation.
595 The sanity checks verify aspects of the VM such as the memory model
596 and other information provided by the architecture. Verbose
597 information will be printed at KERN_DEBUG loglevel depending
598 on the mminit_loglevel= command-line option.
602 config MEMORY_NOTIFIER_ERROR_INJECT
603 tristate "Memory hotplug notifier error injection module"
604 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
606 This option provides the ability to inject artificial errors to
607 memory hotplug notifier chain callbacks. It is controlled through
608 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
610 If the notifier call chain should be failed with some events
611 notified, write the error code to "actions/<notifier event>/error".
613 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
615 # cd /sys/kernel/debug/notifier-error-inject/memory
616 # echo -12 > actions/MEM_GOING_OFFLINE/error
617 # echo offline > /sys/devices/system/memory/memoryXXX/state
618 bash: echo: write error: Cannot allocate memory
620 To compile this code as a module, choose M here: the module will
621 be called memory-notifier-error-inject.
625 config DEBUG_PER_CPU_MAPS
626 bool "Debug access to per_cpu maps"
627 depends on DEBUG_KERNEL
630 Say Y to verify that the per_cpu map being accessed has
631 been set up. This adds a fair amount of code to kernel memory
632 and decreases performance.
637 bool "Highmem debugging"
638 depends on DEBUG_KERNEL && HIGHMEM
640 This option enables additional error checking for high memory
641 systems. Disable for production systems.
643 config HAVE_DEBUG_STACKOVERFLOW
646 config DEBUG_STACKOVERFLOW
647 bool "Check for stack overflows"
648 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
650 Say Y here if you want to check for overflows of kernel, IRQ
651 and exception stacks (if your architecture uses them). This
652 option will show detailed messages if free stack space drops
653 below a certain limit.
655 These kinds of bugs usually occur when call-chains in the
656 kernel get too deep, especially when interrupts are
659 Use this in cases where you see apparently random memory
660 corruption, especially if it appears in 'struct thread_info'
662 If in doubt, say "N".
664 source "lib/Kconfig.kmemcheck"
666 source "lib/Kconfig.kasan"
668 endmenu # "Memory Debugging"
671 bool "Debug shared IRQ handlers"
672 depends on DEBUG_KERNEL
674 Enable this to generate a spurious interrupt as soon as a shared
675 interrupt handler is registered, and just before one is deregistered.
676 Drivers ought to be able to handle interrupts coming in at those
677 points; some don't and need to be caught.
679 menu "Debug Lockups and Hangs"
681 config LOCKUP_DETECTOR
682 bool "Detect Hard and Soft Lockups"
683 depends on DEBUG_KERNEL && !S390
685 Say Y here to enable the kernel to act as a watchdog to detect
686 hard and soft lockups.
688 Softlockups are bugs that cause the kernel to loop in kernel
689 mode for more than 20 seconds, without giving other tasks a
690 chance to run. The current stack trace is displayed upon
691 detection and the system will stay locked up.
693 Hardlockups are bugs that cause the CPU to loop in kernel mode
694 for more than 10 seconds, without letting other interrupts have a
695 chance to run. The current stack trace is displayed upon detection
696 and the system will stay locked up.
698 The overhead should be minimal. A periodic hrtimer runs to
699 generate interrupts and kick the watchdog task every 4 seconds.
700 An NMI is generated every 10 seconds or so to check for hardlockups.
702 The frequency of hrtimer and NMI events and the soft and hard lockup
703 thresholds can be controlled through the sysctl watchdog_thresh.
705 config HARDLOCKUP_DETECTOR
707 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
708 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
710 config BOOTPARAM_HARDLOCKUP_PANIC
711 bool "Panic (Reboot) On Hard Lockups"
712 depends on HARDLOCKUP_DETECTOR
714 Say Y here to enable the kernel to panic on "hard lockups",
715 which are bugs that cause the kernel to loop in kernel
716 mode with interrupts disabled for more than 10 seconds (configurable
717 using the watchdog_thresh sysctl).
721 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
723 depends on HARDLOCKUP_DETECTOR
725 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
726 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
728 config BOOTPARAM_SOFTLOCKUP_PANIC
729 bool "Panic (Reboot) On Soft Lockups"
730 depends on LOCKUP_DETECTOR
732 Say Y here to enable the kernel to panic on "soft lockups",
733 which are bugs that cause the kernel to loop in kernel
734 mode for more than 20 seconds (configurable using the watchdog_thresh
735 sysctl), without giving other tasks a chance to run.
737 The panic can be used in combination with panic_timeout,
738 to cause the system to reboot automatically after a
739 lockup has been detected. This feature is useful for
740 high-availability systems that have uptime guarantees and
741 where a lockup must be resolved ASAP.
745 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
747 depends on LOCKUP_DETECTOR
749 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
750 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
752 config DETECT_HUNG_TASK
753 bool "Detect Hung Tasks"
754 depends on DEBUG_KERNEL
755 default LOCKUP_DETECTOR
757 Say Y here to enable the kernel to detect "hung tasks",
758 which are bugs that cause the task to be stuck in
759 uninterruptible "D" state indefinitiley.
761 When a hung task is detected, the kernel will print the
762 current stack trace (which you should report), but the
763 task will stay in uninterruptible state. If lockdep is
764 enabled then all held locks will also be reported. This
765 feature has negligible overhead.
767 config DEFAULT_HUNG_TASK_TIMEOUT
768 int "Default timeout for hung task detection (in seconds)"
769 depends on DETECT_HUNG_TASK
772 This option controls the default timeout (in seconds) used
773 to determine when a task has become non-responsive and should
776 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
777 sysctl or by writing a value to
778 /proc/sys/kernel/hung_task_timeout_secs.
780 A timeout of 0 disables the check. The default is two minutes.
781 Keeping the default should be fine in most cases.
783 config BOOTPARAM_HUNG_TASK_PANIC
784 bool "Panic (Reboot) On Hung Tasks"
785 depends on DETECT_HUNG_TASK
787 Say Y here to enable the kernel to panic on "hung tasks",
788 which are bugs that cause the kernel to leave a task stuck
789 in uninterruptible "D" state.
791 The panic can be used in combination with panic_timeout,
792 to cause the system to reboot automatically after a
793 hung task has been detected. This feature is useful for
794 high-availability systems that have uptime guarantees and
795 where a hung tasks must be resolved ASAP.
799 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
801 depends on DETECT_HUNG_TASK
803 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
804 default 1 if BOOTPARAM_HUNG_TASK_PANIC
806 endmenu # "Debug lockups and hangs"
811 Say Y here to enable the kernel to panic when it oopses. This
812 has the same effect as setting oops=panic on the kernel command
815 This feature is useful to ensure that the kernel does not do
816 anything erroneous after an oops which could result in data
817 corruption or other issues.
821 config PANIC_ON_OOPS_VALUE
824 default 0 if !PANIC_ON_OOPS
825 default 1 if PANIC_ON_OOPS
831 Set the timeout value (in seconds) until a reboot occurs when the
832 the kernel panics. If n = 0, then we wait forever. A timeout
833 value n > 0 will wait n seconds before rebooting, while a timeout
834 value n < 0 will reboot immediately.
837 bool "Collect scheduler debugging info"
838 depends on DEBUG_KERNEL && PROC_FS
841 If you say Y here, the /proc/sched_debug file will be provided
842 that can help debug the scheduler. The runtime overhead of this
850 bool "Collect scheduler statistics"
851 depends on DEBUG_KERNEL && PROC_FS
854 If you say Y here, additional code will be inserted into the
855 scheduler and related routines to collect statistics about
856 scheduler behavior and provide them in /proc/schedstat. These
857 stats may be useful for both tuning and debugging the scheduler
858 If you aren't debugging the scheduler or trying to tune a specific
859 application, you can say N to avoid the very slight overhead
862 config SCHED_STACK_END_CHECK
863 bool "Detect stack corruption on calls to schedule()"
864 depends on DEBUG_KERNEL
867 This option checks for a stack overrun on calls to schedule().
868 If the stack end location is found to be over written always panic as
869 the content of the corrupted region can no longer be trusted.
870 This is to ensure no erroneous behaviour occurs which could result in
871 data corruption or a sporadic crash at a later stage once the region
872 is examined. The runtime overhead introduced is minimal.
874 config DEBUG_TIMEKEEPING
875 bool "Enable extra timekeeping sanity checking"
877 This option will enable additional timekeeping sanity checks
878 which may be helpful when diagnosing issues where timekeeping
879 problems are suspected.
881 This may include checks in the timekeeping hotpaths, so this
882 option may have a (very small) performance impact to some
888 bool "Collect kernel timers statistics"
889 depends on DEBUG_KERNEL && PROC_FS
891 If you say Y here, additional code will be inserted into the
892 timer routines to collect statistics about kernel timers being
893 reprogrammed. The statistics can be read from /proc/timer_stats.
894 The statistics collection is started by writing 1 to /proc/timer_stats,
895 writing 0 stops it. This feature is useful to collect information
896 about timer usage patterns in kernel and userspace. This feature
897 is lightweight if enabled in the kernel config but not activated
898 (it defaults to deactivated on bootup and will only be activated
899 if some application like powertop activates it explicitly).
902 bool "Debug preemptible kernel"
903 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
906 If you say Y here then the kernel will use a debug variant of the
907 commonly used smp_processor_id() function and will print warnings
908 if kernel code uses it in a preemption-unsafe way. Also, the kernel
909 will detect preemption count underflows.
911 menu "Lock Debugging (spinlocks, mutexes, etc...)"
913 config DEBUG_RT_MUTEXES
914 bool "RT Mutex debugging, deadlock detection"
915 depends on DEBUG_KERNEL && RT_MUTEXES
917 This allows rt mutex semantics violations and rt mutex related
918 deadlocks (lockups) to be detected and reported automatically.
920 config DEBUG_SPINLOCK
921 bool "Spinlock and rw-lock debugging: basic checks"
922 depends on DEBUG_KERNEL
923 select UNINLINE_SPIN_UNLOCK
925 Say Y here and build SMP to catch missing spinlock initialization
926 and certain other kinds of spinlock errors commonly made. This is
927 best used in conjunction with the NMI watchdog so that spinlock
928 deadlocks are also debuggable.
931 bool "Mutex debugging: basic checks"
932 depends on DEBUG_KERNEL
934 This feature allows mutex semantics violations to be detected and
937 config DEBUG_WW_MUTEX_SLOWPATH
938 bool "Wait/wound mutex debugging: Slowpath testing"
939 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
940 select DEBUG_LOCK_ALLOC
941 select DEBUG_SPINLOCK
944 This feature enables slowpath testing for w/w mutex users by
945 injecting additional -EDEADLK wound/backoff cases. Together with
946 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
947 will test all possible w/w mutex interface abuse with the
948 exception of simply not acquiring all the required locks.
949 Note that this feature can introduce significant overhead, so
950 it really should not be enabled in a production or distro kernel,
951 even a debug kernel. If you are a driver writer, enable it. If
952 you are a distro, do not.
954 config DEBUG_LOCK_ALLOC
955 bool "Lock debugging: detect incorrect freeing of live locks"
956 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
957 select DEBUG_SPINLOCK
961 This feature will check whether any held lock (spinlock, rwlock,
962 mutex or rwsem) is incorrectly freed by the kernel, via any of the
963 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
964 vfree(), etc.), whether a live lock is incorrectly reinitialized via
965 spin_lock_init()/mutex_init()/etc., or whether there is any lock
966 held during task exit.
969 bool "Lock debugging: prove locking correctness"
970 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
972 select DEBUG_SPINLOCK
974 select DEBUG_LOCK_ALLOC
975 select TRACE_IRQFLAGS
978 This feature enables the kernel to prove that all locking
979 that occurs in the kernel runtime is mathematically
980 correct: that under no circumstance could an arbitrary (and
981 not yet triggered) combination of observed locking
982 sequences (on an arbitrary number of CPUs, running an
983 arbitrary number of tasks and interrupt contexts) cause a
986 In short, this feature enables the kernel to report locking
987 related deadlocks before they actually occur.
989 The proof does not depend on how hard and complex a
990 deadlock scenario would be to trigger: how many
991 participant CPUs, tasks and irq-contexts would be needed
992 for it to trigger. The proof also does not depend on
993 timing: if a race and a resulting deadlock is possible
994 theoretically (no matter how unlikely the race scenario
995 is), it will be proven so and will immediately be
996 reported by the kernel (once the event is observed that
997 makes the deadlock theoretically possible).
999 If a deadlock is impossible (i.e. the locking rules, as
1000 observed by the kernel, are mathematically correct), the
1001 kernel reports nothing.
1003 NOTE: this feature can also be enabled for rwlocks, mutexes
1004 and rwsems - in which case all dependencies between these
1005 different locking variants are observed and mapped too, and
1006 the proof of observed correctness is also maintained for an
1007 arbitrary combination of these separate locking variants.
1009 For more details, see Documentation/locking/lockdep-design.txt.
1013 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1015 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
1020 bool "Lock usage statistics"
1021 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1023 select DEBUG_SPINLOCK
1024 select DEBUG_MUTEXES
1025 select DEBUG_LOCK_ALLOC
1028 This feature enables tracking lock contention points
1030 For more details, see Documentation/locking/lockstat.txt
1032 This also enables lock events required by "perf lock",
1034 If you want to use "perf lock", you also need to turn on
1035 CONFIG_EVENT_TRACING.
1037 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1038 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1040 config DEBUG_LOCKDEP
1041 bool "Lock dependency engine debugging"
1042 depends on DEBUG_KERNEL && LOCKDEP
1044 If you say Y here, the lock dependency engine will do
1045 additional runtime checks to debug itself, at the price
1046 of more runtime overhead.
1048 config DEBUG_ATOMIC_SLEEP
1049 bool "Sleep inside atomic section checking"
1050 select PREEMPT_COUNT
1051 depends on DEBUG_KERNEL
1053 If you say Y here, various routines which may sleep will become very
1054 noisy if they are called inside atomic sections: when a spinlock is
1055 held, inside an rcu read side critical section, inside preempt disabled
1056 sections, inside an interrupt, etc...
1058 config DEBUG_LOCKING_API_SELFTESTS
1059 bool "Locking API boot-time self-tests"
1060 depends on DEBUG_KERNEL
1062 Say Y here if you want the kernel to run a short self-test during
1063 bootup. The self-test checks whether common types of locking bugs
1064 are detected by debugging mechanisms or not. (if you disable
1065 lock debugging then those bugs wont be detected of course.)
1066 The following locking APIs are covered: spinlocks, rwlocks,
1069 config LOCK_TORTURE_TEST
1070 tristate "torture tests for locking"
1071 depends on DEBUG_KERNEL
1075 This option provides a kernel module that runs torture tests
1076 on kernel locking primitives. The kernel module may be built
1077 after the fact on the running kernel to be tested, if desired.
1079 Say Y here if you want kernel locking-primitive torture tests
1080 to be built into the kernel.
1081 Say M if you want these torture tests to build as a module.
1082 Say N if you are unsure.
1084 endmenu # lock debugging
1086 config TRACE_IRQFLAGS
1089 Enables hooks to interrupt enabling and disabling for
1090 either tracing or lock debugging.
1093 bool "Stack backtrace support"
1094 depends on STACKTRACE_SUPPORT
1096 This option causes the kernel to create a /proc/pid/stack for
1097 every process, showing its current stack trace.
1098 It is also used by various kernel debugging features that require
1099 stack trace generation.
1101 config DEBUG_KOBJECT
1102 bool "kobject debugging"
1103 depends on DEBUG_KERNEL
1105 If you say Y here, some extra kobject debugging messages will be sent
1108 config DEBUG_KOBJECT_RELEASE
1109 bool "kobject release debugging"
1110 depends on DEBUG_OBJECTS_TIMERS
1112 kobjects are reference counted objects. This means that their
1113 last reference count put is not predictable, and the kobject can
1114 live on past the point at which a driver decides to drop it's
1115 initial reference to the kobject gained on allocation. An
1116 example of this would be a struct device which has just been
1119 However, some buggy drivers assume that after such an operation,
1120 the memory backing the kobject can be immediately freed. This
1121 goes completely against the principles of a refcounted object.
1123 If you say Y here, the kernel will delay the release of kobjects
1124 on the last reference count to improve the visibility of this
1125 kind of kobject release bug.
1127 config HAVE_DEBUG_BUGVERBOSE
1130 config DEBUG_BUGVERBOSE
1131 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1132 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1135 Say Y here to make BUG() panics output the file name and line number
1136 of the BUG call as well as the EIP and oops trace. This aids
1137 debugging but costs about 70-100K of memory.
1140 bool "Debug linked list manipulation"
1141 depends on DEBUG_KERNEL
1143 Enable this to turn on extended checks in the linked-list
1148 config DEBUG_PI_LIST
1149 bool "Debug priority linked list manipulation"
1150 depends on DEBUG_KERNEL
1152 Enable this to turn on extended checks in the priority-ordered
1153 linked-list (plist) walking routines. This checks the entire
1154 list multiple times during each manipulation.
1159 bool "Debug SG table operations"
1160 depends on DEBUG_KERNEL
1162 Enable this to turn on checks on scatter-gather tables. This can
1163 help find problems with drivers that do not properly initialize
1168 config DEBUG_NOTIFIERS
1169 bool "Debug notifier call chains"
1170 depends on DEBUG_KERNEL
1172 Enable this to turn on sanity checking for notifier call chains.
1173 This is most useful for kernel developers to make sure that
1174 modules properly unregister themselves from notifier chains.
1175 This is a relatively cheap check but if you care about maximum
1178 config DEBUG_CREDENTIALS
1179 bool "Debug credential management"
1180 depends on DEBUG_KERNEL
1182 Enable this to turn on some debug checking for credential
1183 management. The additional code keeps track of the number of
1184 pointers from task_structs to any given cred struct, and checks to
1185 see that this number never exceeds the usage count of the cred
1188 Furthermore, if SELinux is enabled, this also checks that the
1189 security pointer in the cred struct is never seen to be invalid.
1193 menu "RCU Debugging"
1196 def_bool PROVE_LOCKING
1198 config PROVE_RCU_REPEATEDLY
1199 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1200 depends on PROVE_RCU
1203 By itself, PROVE_RCU will disable checking upon issuing the
1204 first warning (or "splat"). This feature prevents such
1205 disabling, allowing multiple RCU-lockdep warnings to be printed
1208 Say Y to allow multiple RCU-lockdep warnings per boot.
1210 Say N if you are unsure.
1212 config SPARSE_RCU_POINTER
1213 bool "RCU debugging: sparse-based checks for pointer usage"
1216 This feature enables the __rcu sparse annotation for
1217 RCU-protected pointers. This annotation will cause sparse
1218 to flag any non-RCU used of annotated pointers. This can be
1219 helpful when debugging RCU usage. Please note that this feature
1220 is not intended to enforce code cleanliness; it is instead merely
1223 Say Y to make sparse flag questionable use of RCU-protected pointers
1225 Say N if you are unsure.
1231 config RCU_TORTURE_TEST
1232 tristate "torture tests for RCU"
1233 depends on DEBUG_KERNEL
1239 This option provides a kernel module that runs torture tests
1240 on the RCU infrastructure. The kernel module may be built
1241 after the fact on the running kernel to be tested, if desired.
1243 Say Y here if you want RCU torture tests to be built into
1245 Say M if you want the RCU torture tests to build as a module.
1246 Say N if you are unsure.
1248 config RCU_TORTURE_TEST_RUNNABLE
1249 bool "torture tests for RCU runnable by default"
1250 depends on RCU_TORTURE_TEST = y
1253 This option provides a way to build the RCU torture tests
1254 directly into the kernel without them starting up at boot
1255 time. You can use /proc/sys/kernel/rcutorture_runnable
1256 to manually override this setting. This /proc file is
1257 available only when the RCU torture tests have been built
1260 Say Y here if you want the RCU torture tests to start during
1261 boot (you probably don't).
1262 Say N here if you want the RCU torture tests to start only
1263 after being manually enabled via /proc.
1265 config RCU_TORTURE_TEST_SLOW_PREINIT
1266 bool "Slow down RCU grace-period pre-initialization to expose races"
1267 depends on RCU_TORTURE_TEST
1269 This option delays grace-period pre-initialization (the
1270 propagation of CPU-hotplug changes up the rcu_node combining
1271 tree) for a few jiffies between initializing each pair of
1272 consecutive rcu_node structures. This helps to expose races
1273 involving grace-period pre-initialization, in other words, it
1274 makes your kernel less stable. It can also greatly increase
1275 grace-period latency, especially on systems with large numbers
1276 of CPUs. This is useful when torture-testing RCU, but in
1277 almost no other circumstance.
1279 Say Y here if you want your system to crash and hang more often.
1280 Say N if you want a sane system.
1282 config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1283 int "How much to slow down RCU grace-period pre-initialization"
1286 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1288 This option specifies the number of jiffies to wait between
1289 each rcu_node structure pre-initialization step.
1291 config RCU_TORTURE_TEST_SLOW_INIT
1292 bool "Slow down RCU grace-period initialization to expose races"
1293 depends on RCU_TORTURE_TEST
1295 This option delays grace-period initialization for a few
1296 jiffies between initializing each pair of consecutive
1297 rcu_node structures. This helps to expose races involving
1298 grace-period initialization, in other words, it makes your
1299 kernel less stable. It can also greatly increase grace-period
1300 latency, especially on systems with large numbers of CPUs.
1301 This is useful when torture-testing RCU, but in almost no
1304 Say Y here if you want your system to crash and hang more often.
1305 Say N if you want a sane system.
1307 config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1308 int "How much to slow down RCU grace-period initialization"
1311 depends on RCU_TORTURE_TEST_SLOW_INIT
1313 This option specifies the number of jiffies to wait between
1314 each rcu_node structure initialization.
1316 config RCU_TORTURE_TEST_SLOW_CLEANUP
1317 bool "Slow down RCU grace-period cleanup to expose races"
1318 depends on RCU_TORTURE_TEST
1320 This option delays grace-period cleanup for a few jiffies
1321 between cleaning up each pair of consecutive rcu_node
1322 structures. This helps to expose races involving grace-period
1323 cleanup, in other words, it makes your kernel less stable.
1324 It can also greatly increase grace-period latency, especially
1325 on systems with large numbers of CPUs. This is useful when
1326 torture-testing RCU, but in almost no other circumstance.
1328 Say Y here if you want your system to crash and hang more often.
1329 Say N if you want a sane system.
1331 config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1332 int "How much to slow down RCU grace-period cleanup"
1335 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1337 This option specifies the number of jiffies to wait between
1338 each rcu_node structure cleanup operation.
1340 config RCU_CPU_STALL_TIMEOUT
1341 int "RCU CPU stall timeout in seconds"
1342 depends on RCU_STALL_COMMON
1346 If a given RCU grace period extends more than the specified
1347 number of seconds, a CPU stall warning is printed. If the
1348 RCU grace period persists, additional CPU stall warnings are
1349 printed at more widely spaced intervals.
1352 bool "Enable tracing for RCU"
1353 depends on DEBUG_KERNEL
1356 This option provides tracing in RCU which presents stats
1357 in debugfs for debugging RCU implementation.
1359 Say Y here if you want to enable RCU tracing
1360 Say N if you are unsure.
1362 config RCU_EQS_DEBUG
1363 bool "Provide debugging asserts for adding NO_HZ support to an arch"
1364 depends on DEBUG_KERNEL
1366 This option provides consistency checks in RCU's handling of
1367 NO_HZ. These checks have proven quite helpful in detecting
1368 bugs in arch-specific NO_HZ code.
1370 Say N here if you need ultimate kernel/user switch latencies
1371 Say Y if you are unsure
1373 endmenu # "RCU Debugging"
1375 config DEBUG_BLOCK_EXT_DEVT
1376 bool "Force extended block device numbers and spread them"
1377 depends on DEBUG_KERNEL
1381 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1382 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1383 YOU ARE DOING. Distros, please enable this and fix whatever
1386 Conventionally, block device numbers are allocated from
1387 predetermined contiguous area. However, extended block area
1388 may introduce non-contiguous block device numbers. This
1389 option forces most block device numbers to be allocated from
1390 the extended space and spreads them to discover kernel or
1391 userland code paths which assume predetermined contiguous
1392 device number allocation.
1394 Note that turning on this debug option shuffles all the
1395 device numbers for all IDE and SCSI devices including libata
1396 ones, so root partition specified using device number
1397 directly (via rdev or root=MAJ:MIN) won't work anymore.
1398 Textual device names (root=/dev/sdXn) will continue to work.
1400 Say N if you are unsure.
1402 config NOTIFIER_ERROR_INJECTION
1403 tristate "Notifier error injection"
1404 depends on DEBUG_KERNEL
1407 This option provides the ability to inject artificial errors to
1408 specified notifier chain callbacks. It is useful to test the error
1409 handling of notifier call chain failures.
1413 config CPU_NOTIFIER_ERROR_INJECT
1414 tristate "CPU notifier error injection module"
1415 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1417 This option provides a kernel module that can be used to test
1418 the error handling of the cpu notifiers by injecting artificial
1419 errors to CPU notifier chain callbacks. It is controlled through
1420 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1422 If the notifier call chain should be failed with some events
1423 notified, write the error code to "actions/<notifier event>/error".
1425 Example: Inject CPU offline error (-1 == -EPERM)
1427 # cd /sys/kernel/debug/notifier-error-inject/cpu
1428 # echo -1 > actions/CPU_DOWN_PREPARE/error
1429 # echo 0 > /sys/devices/system/cpu/cpu1/online
1430 bash: echo: write error: Operation not permitted
1432 To compile this code as a module, choose M here: the module will
1433 be called cpu-notifier-error-inject.
1437 config PM_NOTIFIER_ERROR_INJECT
1438 tristate "PM notifier error injection module"
1439 depends on PM && NOTIFIER_ERROR_INJECTION
1440 default m if PM_DEBUG
1442 This option provides the ability to inject artificial errors to
1443 PM notifier chain callbacks. It is controlled through debugfs
1444 interface /sys/kernel/debug/notifier-error-inject/pm
1446 If the notifier call chain should be failed with some events
1447 notified, write the error code to "actions/<notifier event>/error".
1449 Example: Inject PM suspend error (-12 = -ENOMEM)
1451 # cd /sys/kernel/debug/notifier-error-inject/pm/
1452 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1453 # echo mem > /sys/power/state
1454 bash: echo: write error: Cannot allocate memory
1456 To compile this code as a module, choose M here: the module will
1457 be called pm-notifier-error-inject.
1461 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1462 tristate "OF reconfig notifier error injection module"
1463 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1465 This option provides the ability to inject artificial errors to
1466 OF reconfig notifier chain callbacks. It is controlled
1467 through debugfs interface under
1468 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1470 If the notifier call chain should be failed with some events
1471 notified, write the error code to "actions/<notifier event>/error".
1473 To compile this code as a module, choose M here: the module will
1474 be called of-reconfig-notifier-error-inject.
1478 config FAULT_INJECTION
1479 bool "Fault-injection framework"
1480 depends on DEBUG_KERNEL
1482 Provide fault-injection framework.
1483 For more details, see Documentation/fault-injection/.
1486 bool "Fault-injection capability for kmalloc"
1487 depends on FAULT_INJECTION
1488 depends on SLAB || SLUB
1490 Provide fault-injection capability for kmalloc.
1492 config FAIL_PAGE_ALLOC
1493 bool "Fault-injection capabilitiy for alloc_pages()"
1494 depends on FAULT_INJECTION
1496 Provide fault-injection capability for alloc_pages().
1498 config FAIL_MAKE_REQUEST
1499 bool "Fault-injection capability for disk IO"
1500 depends on FAULT_INJECTION && BLOCK
1502 Provide fault-injection capability for disk IO.
1504 config FAIL_IO_TIMEOUT
1505 bool "Fault-injection capability for faking disk interrupts"
1506 depends on FAULT_INJECTION && BLOCK
1508 Provide fault-injection capability on end IO handling. This
1509 will make the block layer "forget" an interrupt as configured,
1510 thus exercising the error handling.
1512 Only works with drivers that use the generic timeout handling,
1513 for others it wont do anything.
1515 config FAIL_MMC_REQUEST
1516 bool "Fault-injection capability for MMC IO"
1518 depends on FAULT_INJECTION && MMC
1520 Provide fault-injection capability for MMC IO.
1521 This will make the mmc core return data errors. This is
1522 useful to test the error handling in the mmc block device
1523 and to test how the mmc host driver handles retries from
1527 bool "Fault-injection capability for futexes"
1529 depends on FAULT_INJECTION && FUTEX
1531 Provide fault-injection capability for futexes.
1533 config FAULT_INJECTION_DEBUG_FS
1534 bool "Debugfs entries for fault-injection capabilities"
1535 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1537 Enable configuration of fault-injection capabilities via debugfs.
1539 config FAULT_INJECTION_STACKTRACE_FILTER
1540 bool "stacktrace filter for fault-injection capabilities"
1541 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1544 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1546 Provide stacktrace filter for fault-injection capabilities
1549 bool "Latency measuring infrastructure"
1550 depends on HAVE_LATENCYTOP_SUPPORT
1551 depends on DEBUG_KERNEL
1552 depends on STACKTRACE_SUPPORT
1554 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1561 Enable this option if you want to use the LatencyTOP tool
1562 to find out which userspace is blocking on what kernel operations.
1564 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1567 config DEBUG_STRICT_USER_COPY_CHECKS
1568 bool "Strict user copy size checks"
1569 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1570 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1572 Enabling this option turns a certain set of sanity checks for user
1573 copy operations into compile time failures.
1575 The copy_from_user() etc checks are there to help test if there
1576 are sufficient security checks on the length argument of
1577 the copy operation, by having gcc prove that the argument is
1582 source kernel/trace/Kconfig
1584 menu "Runtime Testing"
1587 tristate "Linux Kernel Dump Test Tool Module"
1592 This module enables testing of the different dumping mechanisms by
1593 inducing system failures at predefined crash points.
1594 If you don't need it: say N
1595 Choose M here to compile this code as a module. The module will be
1598 Documentation on how to use the module can be found in
1599 Documentation/fault-injection/provoke-crashes.txt
1601 config TEST_LIST_SORT
1602 bool "Linked list sorting test"
1603 depends on DEBUG_KERNEL
1605 Enable this to turn on 'list_sort()' function test. This test is
1606 executed only once during system boot, so affects only boot time.
1610 config KPROBES_SANITY_TEST
1611 bool "Kprobes sanity tests"
1612 depends on DEBUG_KERNEL
1616 This option provides for testing basic kprobes functionality on
1617 boot. A sample kprobe, jprobe and kretprobe are inserted and
1618 verified for functionality.
1620 Say N if you are unsure.
1622 config BACKTRACE_SELF_TEST
1623 tristate "Self test for the backtrace code"
1624 depends on DEBUG_KERNEL
1627 This option provides a kernel module that can be used to test
1628 the kernel stack backtrace code. This option is not useful
1629 for distributions or general kernels, but only for kernel
1630 developers working on architecture code.
1632 Note that if you want to also test saved backtraces, you will
1633 have to enable STACKTRACE as well.
1635 Say N if you are unsure.
1638 tristate "Red-Black tree test"
1639 depends on DEBUG_KERNEL
1641 A benchmark measuring the performance of the rbtree library.
1642 Also includes rbtree invariant checks.
1644 config INTERVAL_TREE_TEST
1645 tristate "Interval tree test"
1646 depends on m && DEBUG_KERNEL
1647 select INTERVAL_TREE
1649 A benchmark measuring the performance of the interval tree library
1652 tristate "Per cpu operations test"
1653 depends on m && DEBUG_KERNEL
1655 Enable this option to build test module which validates per-cpu
1660 config ATOMIC64_SELFTEST
1661 bool "Perform an atomic64_t self-test at boot"
1663 Enable this option to test the atomic64_t functions at boot.
1667 config ASYNC_RAID6_TEST
1668 tristate "Self test for hardware accelerated raid6 recovery"
1669 depends on ASYNC_RAID6_RECOV
1672 This is a one-shot self test that permutes through the
1673 recovery of all the possible two disk failure scenarios for a
1674 N-disk array. Recovery is performed with the asynchronous
1675 raid6 recovery routines, and will optionally use an offload
1676 engine if one is available.
1681 tristate "Test functions located in the hexdump module at runtime"
1683 config TEST_STRING_HELPERS
1684 tristate "Test functions located in the string_helpers module at runtime"
1687 tristate "Test kstrto*() family of functions at runtime"
1689 config TEST_RHASHTABLE
1690 tristate "Perform selftest on resizable hash table"
1693 Enable this option to test the rhashtable functions at boot.
1697 endmenu # runtime tests
1699 config PROVIDE_OHCI1394_DMA_INIT
1700 bool "Remote debugging over FireWire early on boot"
1701 depends on PCI && X86
1703 If you want to debug problems which hang or crash the kernel early
1704 on boot and the crashing machine has a FireWire port, you can use
1705 this feature to remotely access the memory of the crashed machine
1706 over FireWire. This employs remote DMA as part of the OHCI1394
1707 specification which is now the standard for FireWire controllers.
1709 With remote DMA, you can monitor the printk buffer remotely using
1710 firescope and access all memory below 4GB using fireproxy from gdb.
1711 Even controlling a kernel debugger is possible using remote DMA.
1715 If ohci1394_dma=early is used as boot parameter, it will initialize
1716 all OHCI1394 controllers which are found in the PCI config space.
1718 As all changes to the FireWire bus such as enabling and disabling
1719 devices cause a bus reset and thereby disable remote DMA for all
1720 devices, be sure to have the cable plugged and FireWire enabled on
1721 the debugging host before booting the debug target for debugging.
1723 This code (~1k) is freed after boot. By then, the firewire stack
1724 in charge of the OHCI-1394 controllers should be used instead.
1726 See Documentation/debugging-via-ohci1394.txt for more information.
1729 bool "Build targets in Documentation/ tree"
1730 depends on HEADERS_CHECK
1732 This option attempts to build objects from the source files in the
1733 kernel Documentation/ tree.
1735 Say N if you are unsure.
1737 config DMA_API_DEBUG
1738 bool "Enable debugging of DMA-API usage"
1739 depends on HAVE_DMA_API_DEBUG
1741 Enable this option to debug the use of the DMA API by device drivers.
1742 With this option you will be able to detect common bugs in device
1743 drivers like double-freeing of DMA mappings or freeing mappings that
1744 were never allocated.
1746 This also attempts to catch cases where a page owned by DMA is
1747 accessed by the cpu in a way that could cause data corruption. For
1748 example, this enables cow_user_page() to check that the source page is
1751 This option causes a performance degradation. Use only if you want to
1752 debug device drivers and dma interactions.
1757 tristate "Test module loading with 'hello world' module"
1761 This builds the "test_module" module that emits "Hello, world"
1762 on printk when loaded. It is designed to be used for basic
1763 evaluation of the module loading subsystem (for example when
1764 validating module verification). It lacks any extra dependencies,
1765 and will not normally be loaded by the system unless explicitly
1770 config TEST_USER_COPY
1771 tristate "Test user/kernel boundary protections"
1775 This builds the "test_user_copy" module that runs sanity checks
1776 on the copy_to/from_user infrastructure, making sure basic
1777 user/kernel boundary testing is working. If it fails to load,
1778 a regression has been detected in the user/kernel memory boundary
1784 tristate "Test BPF filter functionality"
1788 This builds the "test_bpf" module that runs various test vectors
1789 against the BPF interpreter or BPF JIT compiler depending on the
1790 current setting. This is in particular useful for BPF JIT compiler
1791 development, but also to run regression tests against changes in
1792 the interpreter code. It also enables test stubs for eBPF maps and
1793 verifier used by user space verifier testsuite.
1797 config TEST_FIRMWARE
1798 tristate "Test firmware loading via userspace interface"
1800 depends on FW_LOADER
1802 This builds the "test_firmware" module that creates a userspace
1803 interface for testing firmware loading. This can be used to
1804 control the triggering of firmware loading without needing an
1805 actual firmware-using device. The contents can be rechecked by
1811 tristate "udelay test driver"
1814 This builds the "udelay_test" module that helps to make sure
1815 that udelay() is working properly.
1821 depends on HAVE_MEMBLOCK
1823 This option adds a kernel parameter 'memtest', which allows memtest
1825 memtest=0, mean disabled; -- default
1826 memtest=1, mean do 1 test pattern;
1828 memtest=17, mean do 17 test patterns.
1829 If you are unsure how to answer this question, answer N.
1831 config TEST_STATIC_KEYS
1832 tristate "Test static keys"
1836 Test the static key interfaces.
1840 source "samples/Kconfig"
1842 source "lib/Kconfig.kgdb"
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