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 && !FRV
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)"
200 default 2048 if GCC_PLUGIN_LATENT_ENTROPY
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
248 select PAGE_EXTENSION
250 This keeps track of what call chain is the owner of a page, may
251 help to find bare alloc_page(s) leaks. Even if you include this
252 feature on your build, it is disabled in default. You should pass
253 "page_owner=on" to boot parameter in order to enable it. Eats
254 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
255 for user-space helper.
259 config PAGE_OWNER_ENABLE_DEFAULT
260 bool "Enable Track page owner by default"
261 depends on PAGE_OWNER
263 Enable track page owner by default? This value
264 can be overridden by page_owner_disabled=off|on.
267 bool "Debug Filesystem"
269 debugfs is a virtual file system that kernel developers use to put
270 debugging files into. Enable this option to be able to read and
271 write to these files.
273 For detailed documentation on the debugfs API, see
274 Documentation/DocBook/filesystems.
279 bool "Run 'make headers_check' when building vmlinux"
282 This option will extract the user-visible kernel headers whenever
283 building the kernel, and will run basic sanity checks on them to
284 ensure that exported files do not attempt to include files which
285 were not exported, etc.
287 If you're making modifications to header files which are
288 relevant for userspace, say 'Y', and check the headers
289 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
290 your build tree), to make sure they're suitable.
292 config DEBUG_SECTION_MISMATCH
293 bool "Enable full Section mismatch analysis"
295 The section mismatch analysis checks if there are illegal
296 references from one section to another section.
297 During linktime or runtime, some sections are dropped;
298 any use of code/data previously in these sections would
299 most likely result in an oops.
300 In the code, functions and variables are annotated with
301 __init,, etc. (see the full list in include/linux/init.h),
302 which results in the code/data being placed in specific sections.
303 The section mismatch analysis is always performed after a full
304 kernel build, and enabling this option causes the following
305 additional steps to occur:
306 - Add the option -fno-inline-functions-called-once to gcc commands.
307 When inlining a function annotated with __init in a non-init
308 function, we would lose the section information and thus
309 the analysis would not catch the illegal reference.
310 This option tells gcc to inline less (but it does result in
312 - Run the section mismatch analysis for each module/built-in.o file.
313 When we run the section mismatch analysis on vmlinux.o, we
314 lose valueble information about where the mismatch was
316 Running the analysis for each module/built-in.o file
317 tells where the mismatch happens much closer to the
318 source. The drawback is that the same mismatch is
319 reported at least twice.
320 - Enable verbose reporting from modpost in order to help resolve
321 the section mismatches that are reported.
323 config SECTION_MISMATCH_WARN_ONLY
324 bool "Make section mismatch errors non-fatal"
327 If you say N here, the build process will fail if there are any
328 section mismatch, instead of just throwing warnings.
333 # Select this config option from the architecture Kconfig, if it
334 # is preferred to always offer frame pointers as a config
335 # option on the architecture (regardless of KERNEL_DEBUG):
337 config ARCH_WANT_FRAME_POINTERS
342 bool "Compile the kernel with frame pointers"
343 depends on DEBUG_KERNEL && \
344 (CRIS || M68K || FRV || UML || \
345 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
346 ARCH_WANT_FRAME_POINTERS
347 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
349 If you say Y here the resulting kernel image will be slightly
350 larger and slower, but it gives very useful debugging information
351 in case of kernel bugs. (precise oopses/stacktraces/warnings)
353 config DEBUG_FORCE_WEAK_PER_CPU
354 bool "Force weak per-cpu definitions"
355 depends on DEBUG_KERNEL
357 s390 and alpha require percpu variables in modules to be
358 defined weak to work around addressing range issue which
359 puts the following two restrictions on percpu variable
362 1. percpu symbols must be unique whether static or not
363 2. percpu variables can't be defined inside a function
365 To ensure that generic code follows the above rules, this
366 option forces all percpu variables to be defined as weak.
368 endmenu # "Compiler options"
371 bool "Magic SysRq key"
374 If you say Y here, you will have some control over the system even
375 if the system crashes for example during kernel debugging (e.g., you
376 will be able to flush the buffer cache to disk, reboot the system
377 immediately or dump some status information). This is accomplished
378 by pressing various keys while holding SysRq (Alt+PrintScreen). It
379 also works on a serial console (on PC hardware at least), if you
380 send a BREAK and then within 5 seconds a command keypress. The
381 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
382 unless you really know what this hack does.
384 config MAGIC_SYSRQ_DEFAULT_ENABLE
385 hex "Enable magic SysRq key functions by default"
386 depends on MAGIC_SYSRQ
389 Specifies which SysRq key functions are enabled by default.
390 This may be set to 1 or 0 to enable or disable them all, or
391 to a bitmask as described in Documentation/sysrq.txt.
394 bool "Kernel debugging"
396 Say Y here if you are developing drivers or trying to debug and
397 identify kernel problems.
399 menu "Memory Debugging"
401 source mm/Kconfig.debug
404 bool "Debug object operations"
405 depends on DEBUG_KERNEL
407 If you say Y here, additional code will be inserted into the
408 kernel to track the life time of various objects and validate
409 the operations on those objects.
411 config DEBUG_OBJECTS_SELFTEST
412 bool "Debug objects selftest"
413 depends on DEBUG_OBJECTS
415 This enables the selftest of the object debug code.
417 config DEBUG_OBJECTS_FREE
418 bool "Debug objects in freed memory"
419 depends on DEBUG_OBJECTS
421 This enables checks whether a k/v free operation frees an area
422 which contains an object which has not been deactivated
423 properly. This can make kmalloc/kfree-intensive workloads
426 config DEBUG_OBJECTS_TIMERS
427 bool "Debug timer objects"
428 depends on DEBUG_OBJECTS
430 If you say Y here, additional code will be inserted into the
431 timer routines to track the life time of timer objects and
432 validate the timer operations.
434 config DEBUG_OBJECTS_WORK
435 bool "Debug work objects"
436 depends on DEBUG_OBJECTS
438 If you say Y here, additional code will be inserted into the
439 work queue routines to track the life time of work objects and
440 validate the work operations.
442 config DEBUG_OBJECTS_RCU_HEAD
443 bool "Debug RCU callbacks objects"
444 depends on DEBUG_OBJECTS
446 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
448 config DEBUG_OBJECTS_PERCPU_COUNTER
449 bool "Debug percpu counter objects"
450 depends on DEBUG_OBJECTS
452 If you say Y here, additional code will be inserted into the
453 percpu counter routines to track the life time of percpu counter
454 objects and validate the percpu counter operations.
456 config DEBUG_OBJECTS_ENABLE_DEFAULT
457 int "debug_objects bootup default value (0-1)"
460 depends on DEBUG_OBJECTS
462 Debug objects boot parameter default value
465 bool "Debug slab memory allocations"
466 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
468 Say Y here to have the kernel do limited verification on memory
469 allocation as well as poisoning memory on free to catch use of freed
470 memory. This can make kmalloc/kfree-intensive workloads much slower.
472 config DEBUG_SLAB_LEAK
473 bool "Memory leak debugging"
474 depends on DEBUG_SLAB
477 bool "SLUB debugging on by default"
478 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
481 Boot with debugging on by default. SLUB boots by default with
482 the runtime debug capabilities switched off. Enabling this is
483 equivalent to specifying the "slub_debug" parameter on boot.
484 There is no support for more fine grained debug control like
485 possible with slub_debug=xxx. SLUB debugging may be switched
486 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
491 bool "Enable SLUB performance statistics"
492 depends on SLUB && SYSFS
494 SLUB statistics are useful to debug SLUBs allocation behavior in
495 order find ways to optimize the allocator. This should never be
496 enabled for production use since keeping statistics slows down
497 the allocator by a few percentage points. The slabinfo command
498 supports the determination of the most active slabs to figure
499 out which slabs are relevant to a particular load.
500 Try running: slabinfo -DA
502 config HAVE_DEBUG_KMEMLEAK
505 config DEBUG_KMEMLEAK
506 bool "Kernel memory leak detector"
507 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
509 select STACKTRACE if STACKTRACE_SUPPORT
513 Say Y here if you want to enable the memory leak
514 detector. The memory allocation/freeing is traced in a way
515 similar to the Boehm's conservative garbage collector, the
516 difference being that the orphan objects are not freed but
517 only shown in /sys/kernel/debug/kmemleak. Enabling this
518 feature will introduce an overhead to memory
519 allocations. See Documentation/kmemleak.txt for more
522 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
523 of finding leaks due to the slab objects poisoning.
525 In order to access the kmemleak file, debugfs needs to be
526 mounted (usually at /sys/kernel/debug).
528 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
529 int "Maximum kmemleak early log entries"
530 depends on DEBUG_KMEMLEAK
534 Kmemleak must track all the memory allocations to avoid
535 reporting false positives. Since memory may be allocated or
536 freed before kmemleak is initialised, an early log buffer is
537 used to store these actions. If kmemleak reports "early log
538 buffer exceeded", please increase this value.
540 config DEBUG_KMEMLEAK_TEST
541 tristate "Simple test for the kernel memory leak detector"
542 depends on DEBUG_KMEMLEAK && m
544 This option enables a module that explicitly leaks memory.
548 config DEBUG_KMEMLEAK_DEFAULT_OFF
549 bool "Default kmemleak to off"
550 depends on DEBUG_KMEMLEAK
552 Say Y here to disable kmemleak by default. It can then be enabled
553 on the command line via kmemleak=on.
555 config DEBUG_STACK_USAGE
556 bool "Stack utilization instrumentation"
557 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
559 Enables the display of the minimum amount of free stack which each
560 task has ever had available in the sysrq-T and sysrq-P debug output.
562 This option will slow down process creation somewhat.
566 depends on DEBUG_KERNEL
568 Enable this to turn on extended checks in the virtual-memory system
569 that may impact performance.
573 config DEBUG_VM_VMACACHE
574 bool "Debug VMA caching"
577 Enable this to turn on VMA caching debug information. Doing so
578 can cause significant overhead, so only enable it in non-production
584 bool "Debug VM red-black trees"
587 Enable VM red-black tree debugging information and extra validations.
591 config DEBUG_VM_PGFLAGS
592 bool "Debug page-flags operations"
595 Enables extra validation on page flags operations.
600 bool "Debug VM translations"
601 depends on DEBUG_KERNEL && X86
603 Enable some costly sanity checks in virtual to page code. This can
604 catch mistakes with virt_to_page() and friends.
608 config DEBUG_NOMMU_REGIONS
609 bool "Debug the global anon/private NOMMU mapping region tree"
610 depends on DEBUG_KERNEL && !MMU
612 This option causes the global tree of anonymous and private mapping
613 regions to be regularly checked for invalid topology.
615 config DEBUG_MEMORY_INIT
616 bool "Debug memory initialisation" if EXPERT
619 Enable this for additional checks during memory initialisation.
620 The sanity checks verify aspects of the VM such as the memory model
621 and other information provided by the architecture. Verbose
622 information will be printed at KERN_DEBUG loglevel depending
623 on the mminit_loglevel= command-line option.
627 config MEMORY_NOTIFIER_ERROR_INJECT
628 tristate "Memory hotplug notifier error injection module"
629 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
631 This option provides the ability to inject artificial errors to
632 memory hotplug notifier chain callbacks. It is controlled through
633 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
635 If the notifier call chain should be failed with some events
636 notified, write the error code to "actions/<notifier event>/error".
638 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
640 # cd /sys/kernel/debug/notifier-error-inject/memory
641 # echo -12 > actions/MEM_GOING_OFFLINE/error
642 # echo offline > /sys/devices/system/memory/memoryXXX/state
643 bash: echo: write error: Cannot allocate memory
645 To compile this code as a module, choose M here: the module will
646 be called memory-notifier-error-inject.
650 config DEBUG_PER_CPU_MAPS
651 bool "Debug access to per_cpu maps"
652 depends on DEBUG_KERNEL
655 Say Y to verify that the per_cpu map being accessed has
656 been set up. This adds a fair amount of code to kernel memory
657 and decreases performance.
662 bool "Highmem debugging"
663 depends on DEBUG_KERNEL && HIGHMEM
665 This option enables additional error checking for high memory
666 systems. Disable for production systems.
668 config HAVE_DEBUG_STACKOVERFLOW
671 config DEBUG_STACKOVERFLOW
672 bool "Check for stack overflows"
673 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
675 Say Y here if you want to check for overflows of kernel, IRQ
676 and exception stacks (if your architecture uses them). This
677 option will show detailed messages if free stack space drops
678 below a certain limit.
680 These kinds of bugs usually occur when call-chains in the
681 kernel get too deep, especially when interrupts are
684 Use this in cases where you see apparently random memory
685 corruption, especially if it appears in 'struct thread_info'
687 If in doubt, say "N".
689 source "lib/Kconfig.kmemcheck"
691 source "lib/Kconfig.kasan"
693 endmenu # "Memory Debugging"
698 KCOV does not have any arch-specific code, but currently it is enabled
699 only for x86_64. KCOV requires testing on other archs, and most likely
700 disabling of instrumentation for some early boot code.
703 bool "Code coverage for fuzzing"
704 depends on ARCH_HAS_KCOV
707 KCOV exposes kernel code coverage information in a form suitable
708 for coverage-guided fuzzing (randomized testing).
710 If RANDOMIZE_BASE is enabled, PC values will not be stable across
711 different machines and across reboots. If you need stable PC values,
712 disable RANDOMIZE_BASE.
714 For more details, see Documentation/kcov.txt.
717 bool "Debug shared IRQ handlers"
718 depends on DEBUG_KERNEL
720 Enable this to generate a spurious interrupt as soon as a shared
721 interrupt handler is registered, and just before one is deregistered.
722 Drivers ought to be able to handle interrupts coming in at those
723 points; some don't and need to be caught.
725 menu "Debug Lockups and Hangs"
727 config LOCKUP_DETECTOR
728 bool "Detect Hard and Soft Lockups"
729 depends on DEBUG_KERNEL && !S390
731 Say Y here to enable the kernel to act as a watchdog to detect
732 hard and soft lockups.
734 Softlockups are bugs that cause the kernel to loop in kernel
735 mode for more than 20 seconds, without giving other tasks a
736 chance to run. The current stack trace is displayed upon
737 detection and the system will stay locked up.
739 Hardlockups are bugs that cause the CPU to loop in kernel mode
740 for more than 10 seconds, without letting other interrupts have a
741 chance to run. The current stack trace is displayed upon detection
742 and the system will stay locked up.
744 The overhead should be minimal. A periodic hrtimer runs to
745 generate interrupts and kick the watchdog task every 4 seconds.
746 An NMI is generated every 10 seconds or so to check for hardlockups.
747 If NMIs are not available on the platform, every 12 seconds the
748 hrtimer interrupt on one cpu will be used to check for hardlockups
751 The frequency of hrtimer and NMI events and the soft and hard lockup
752 thresholds can be controlled through the sysctl watchdog_thresh.
754 config HARDLOCKUP_DETECTOR_NMI
756 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
757 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
759 config HARDLOCKUP_DETECTOR_OTHER_CPU
761 depends on LOCKUP_DETECTOR && SMP
762 depends on !HARDLOCKUP_DETECTOR_NMI && !HAVE_NMI_WATCHDOG
764 config HARDLOCKUP_DETECTOR
766 depends on HARDLOCKUP_DETECTOR_NMI || HARDLOCKUP_DETECTOR_OTHER_CPU
768 config BOOTPARAM_HARDLOCKUP_PANIC
769 bool "Panic (Reboot) On Hard Lockups"
770 depends on HARDLOCKUP_DETECTOR
772 Say Y here to enable the kernel to panic on "hard lockups",
773 which are bugs that cause the kernel to loop in kernel
774 mode with interrupts disabled for more than 10 seconds (configurable
775 using the watchdog_thresh sysctl).
779 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
781 depends on HARDLOCKUP_DETECTOR
783 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
784 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
786 config BOOTPARAM_SOFTLOCKUP_PANIC
787 bool "Panic (Reboot) On Soft Lockups"
788 depends on LOCKUP_DETECTOR
790 Say Y here to enable the kernel to panic on "soft lockups",
791 which are bugs that cause the kernel to loop in kernel
792 mode for more than 20 seconds (configurable using the watchdog_thresh
793 sysctl), without giving other tasks a chance to run.
795 The panic can be used in combination with panic_timeout,
796 to cause the system to reboot automatically after a
797 lockup has been detected. This feature is useful for
798 high-availability systems that have uptime guarantees and
799 where a lockup must be resolved ASAP.
803 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
805 depends on LOCKUP_DETECTOR
807 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
808 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
810 config DETECT_HUNG_TASK
811 bool "Detect Hung Tasks"
812 depends on DEBUG_KERNEL
813 default LOCKUP_DETECTOR
815 Say Y here to enable the kernel to detect "hung tasks",
816 which are bugs that cause the task to be stuck in
817 uninterruptible "D" state indefinitiley.
819 When a hung task is detected, the kernel will print the
820 current stack trace (which you should report), but the
821 task will stay in uninterruptible state. If lockdep is
822 enabled then all held locks will also be reported. This
823 feature has negligible overhead.
825 config DEFAULT_HUNG_TASK_TIMEOUT
826 int "Default timeout for hung task detection (in seconds)"
827 depends on DETECT_HUNG_TASK
830 This option controls the default timeout (in seconds) used
831 to determine when a task has become non-responsive and should
834 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
835 sysctl or by writing a value to
836 /proc/sys/kernel/hung_task_timeout_secs.
838 A timeout of 0 disables the check. The default is two minutes.
839 Keeping the default should be fine in most cases.
841 config BOOTPARAM_HUNG_TASK_PANIC
842 bool "Panic (Reboot) On Hung Tasks"
843 depends on DETECT_HUNG_TASK
845 Say Y here to enable the kernel to panic on "hung tasks",
846 which are bugs that cause the kernel to leave a task stuck
847 in uninterruptible "D" state.
849 The panic can be used in combination with panic_timeout,
850 to cause the system to reboot automatically after a
851 hung task has been detected. This feature is useful for
852 high-availability systems that have uptime guarantees and
853 where a hung tasks must be resolved ASAP.
857 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
859 depends on DETECT_HUNG_TASK
861 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
862 default 1 if BOOTPARAM_HUNG_TASK_PANIC
865 bool "Detect Workqueue Stalls"
866 depends on DEBUG_KERNEL
868 Say Y here to enable stall detection on workqueues. If a
869 worker pool doesn't make forward progress on a pending work
870 item for over a given amount of time, 30s by default, a
871 warning message is printed along with dump of workqueue
872 state. This can be configured through kernel parameter
873 "workqueue.watchdog_thresh" and its sysfs counterpart.
875 endmenu # "Debug lockups and hangs"
880 Say Y here to enable the kernel to panic when it oopses. This
881 has the same effect as setting oops=panic on the kernel command
884 This feature is useful to ensure that the kernel does not do
885 anything erroneous after an oops which could result in data
886 corruption or other issues.
890 config PANIC_ON_OOPS_VALUE
893 default 0 if !PANIC_ON_OOPS
894 default 1 if PANIC_ON_OOPS
900 Set the timeout value (in seconds) until a reboot occurs when the
901 the kernel panics. If n = 0, then we wait forever. A timeout
902 value n > 0 will wait n seconds before rebooting, while a timeout
903 value n < 0 will reboot immediately.
906 bool "Collect scheduler debugging info"
907 depends on DEBUG_KERNEL && PROC_FS
910 If you say Y here, the /proc/sched_debug file will be provided
911 that can help debug the scheduler. The runtime overhead of this
918 config PANIC_ON_SCHED_BUG
919 bool "Panic on all bugs encountered by the scheduler"
921 Say Y here to panic on all 'BUG:' conditions encountered by the
922 scheduler, even potentially-recoverable ones such as scheduling
923 while atomic, sleeping from invalid context, and detection of
924 broken arch topologies.
928 config PANIC_ON_RT_THROTTLING
929 bool "Panic on RT throttling"
931 Say Y here to enable the kernel to panic when a realtime
932 runqueue is throttled. This may be useful for detecting
933 and debugging RT throttling issues.
937 config SYSRQ_SCHED_DEBUG
938 bool "Print scheduling debugging info from sysrq-trigger"
939 depends on SCHED_DEBUG
942 If you say Y here, the "show-task-states(T)" and
943 "show-blocked-tasks(W)" sysrq-triggers will print additional
944 scheduling statistics.
947 bool "Collect scheduler statistics"
948 depends on DEBUG_KERNEL && PROC_FS
951 If you say Y here, additional code will be inserted into the
952 scheduler and related routines to collect statistics about
953 scheduler behavior and provide them in /proc/schedstat. These
954 stats may be useful for both tuning and debugging the scheduler
955 If you aren't debugging the scheduler or trying to tune a specific
956 application, you can say N to avoid the very slight overhead
959 config SCHED_STACK_END_CHECK
960 bool "Detect stack corruption on calls to schedule()"
961 depends on DEBUG_KERNEL
964 This option checks for a stack overrun on calls to schedule().
965 If the stack end location is found to be over written always panic as
966 the content of the corrupted region can no longer be trusted.
967 This is to ensure no erroneous behaviour occurs which could result in
968 data corruption or a sporadic crash at a later stage once the region
969 is examined. The runtime overhead introduced is minimal.
971 config DEBUG_TIMEKEEPING
972 bool "Enable extra timekeeping sanity checking"
974 This option will enable additional timekeeping sanity checks
975 which may be helpful when diagnosing issues where timekeeping
976 problems are suspected.
978 This may include checks in the timekeeping hotpaths, so this
979 option may have a (very small) performance impact to some
984 config DEBUG_TASK_STACK_SCAN_OFF
985 bool "Disable kmemleak task stack scan by default"
986 depends on DEBUG_KMEMLEAK
988 Say Y here to disable kmemleak task stack scan by default
989 at compile time. It can be enabled later if required by
990 writing to the debugfs entry :
991 echo "stack=on" > /sys/kernel/debug/kmemleak.
993 config DEBUG_MODULE_SCAN_OFF
994 bool "Disable module memory scan for leaks by default"
995 depends on DEBUG_KMEMLEAK
997 Say Y here to disable scanning kernel modules area list
998 by default for memory leaks. Module scan an potentially
999 run with irq/preemption disabled for considerable amount
1002 config DEBUG_PREEMPT
1003 bool "Debug preemptible kernel"
1004 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1007 If you say Y here then the kernel will use a debug variant of the
1008 commonly used smp_processor_id() function and will print warnings
1009 if kernel code uses it in a preemption-unsafe way. Also, the kernel
1010 will detect preemption count underflows.
1012 menu "Lock Debugging (spinlocks, mutexes, etc...)"
1014 config DEBUG_RT_MUTEXES
1015 bool "RT Mutex debugging, deadlock detection"
1016 depends on DEBUG_KERNEL && RT_MUTEXES
1018 This allows rt mutex semantics violations and rt mutex related
1019 deadlocks (lockups) to be detected and reported automatically.
1021 config DEBUG_SPINLOCK
1022 bool "Spinlock and rw-lock debugging: basic checks"
1023 depends on DEBUG_KERNEL
1024 select UNINLINE_SPIN_UNLOCK
1026 Say Y here and build SMP to catch missing spinlock initialization
1027 and certain other kinds of spinlock errors commonly made. This is
1028 best used in conjunction with the NMI watchdog so that spinlock
1029 deadlocks are also debuggable.
1032 prompt "Perform Action on spinlock bug"
1033 depends on DEBUG_SPINLOCK
1035 default DEBUG_SPINLOCK_BITE_ON_BUG
1037 config DEBUG_SPINLOCK_BITE_ON_BUG
1038 bool "Cause a Watchdog Bite on Spinlock bug"
1039 depends on QCOM_WATCHDOG_V2
1041 On a spinlock bug, cause a watchdog bite so that we can get the precise
1042 state of the system captured at the time of spin dump. This is mutually
1043 exclusive with the below DEBUG_SPINLOCK_PANIC_ON_BUG config.
1045 config DEBUG_SPINLOCK_PANIC_ON_BUG
1046 bool "Cause a Kernel Panic on Spinlock bug"
1048 On a spinlock bug, cause a kernel panic so that we can get the complete
1049 information about the system at the time of spin dump in the dmesg.
1050 This is mutually exclusive with the above DEBUG_SPINLOCK_BITE_ON_BUG.
1053 config DEBUG_MUTEXES
1054 bool "Mutex debugging: basic checks"
1055 depends on DEBUG_KERNEL
1057 This feature allows mutex semantics violations to be detected and
1060 config DEBUG_WW_MUTEX_SLOWPATH
1061 bool "Wait/wound mutex debugging: Slowpath testing"
1062 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1063 select DEBUG_LOCK_ALLOC
1064 select DEBUG_SPINLOCK
1065 select DEBUG_MUTEXES
1067 This feature enables slowpath testing for w/w mutex users by
1068 injecting additional -EDEADLK wound/backoff cases. Together with
1069 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1070 will test all possible w/w mutex interface abuse with the
1071 exception of simply not acquiring all the required locks.
1072 Note that this feature can introduce significant overhead, so
1073 it really should not be enabled in a production or distro kernel,
1074 even a debug kernel. If you are a driver writer, enable it. If
1075 you are a distro, do not.
1077 config DEBUG_LOCK_ALLOC
1078 bool "Lock debugging: detect incorrect freeing of live locks"
1079 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1080 select DEBUG_SPINLOCK
1081 select DEBUG_MUTEXES
1084 This feature will check whether any held lock (spinlock, rwlock,
1085 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1086 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1087 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1088 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1089 held during task exit.
1091 config PROVE_LOCKING
1092 bool "Lock debugging: prove locking correctness"
1093 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1095 select DEBUG_SPINLOCK
1096 select DEBUG_MUTEXES
1097 select DEBUG_LOCK_ALLOC
1098 select TRACE_IRQFLAGS
1101 This feature enables the kernel to prove that all locking
1102 that occurs in the kernel runtime is mathematically
1103 correct: that under no circumstance could an arbitrary (and
1104 not yet triggered) combination of observed locking
1105 sequences (on an arbitrary number of CPUs, running an
1106 arbitrary number of tasks and interrupt contexts) cause a
1109 In short, this feature enables the kernel to report locking
1110 related deadlocks before they actually occur.
1112 The proof does not depend on how hard and complex a
1113 deadlock scenario would be to trigger: how many
1114 participant CPUs, tasks and irq-contexts would be needed
1115 for it to trigger. The proof also does not depend on
1116 timing: if a race and a resulting deadlock is possible
1117 theoretically (no matter how unlikely the race scenario
1118 is), it will be proven so and will immediately be
1119 reported by the kernel (once the event is observed that
1120 makes the deadlock theoretically possible).
1122 If a deadlock is impossible (i.e. the locking rules, as
1123 observed by the kernel, are mathematically correct), the
1124 kernel reports nothing.
1126 NOTE: this feature can also be enabled for rwlocks, mutexes
1127 and rwsems - in which case all dependencies between these
1128 different locking variants are observed and mapped too, and
1129 the proof of observed correctness is also maintained for an
1130 arbitrary combination of these separate locking variants.
1132 For more details, see Documentation/locking/lockdep-design.txt.
1136 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1138 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
1143 bool "Lock usage statistics"
1144 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1146 select DEBUG_SPINLOCK
1147 select DEBUG_MUTEXES
1148 select DEBUG_LOCK_ALLOC
1151 This feature enables tracking lock contention points
1153 For more details, see Documentation/locking/lockstat.txt
1155 This also enables lock events required by "perf lock",
1157 If you want to use "perf lock", you also need to turn on
1158 CONFIG_EVENT_TRACING.
1160 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1161 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1163 config DEBUG_LOCKDEP
1164 bool "Lock dependency engine debugging"
1165 depends on DEBUG_KERNEL && LOCKDEP
1167 If you say Y here, the lock dependency engine will do
1168 additional runtime checks to debug itself, at the price
1169 of more runtime overhead.
1171 config DEBUG_ATOMIC_SLEEP
1172 bool "Sleep inside atomic section checking"
1173 select PREEMPT_COUNT
1174 depends on DEBUG_KERNEL
1176 If you say Y here, various routines which may sleep will become very
1177 noisy if they are called inside atomic sections: when a spinlock is
1178 held, inside an rcu read side critical section, inside preempt disabled
1179 sections, inside an interrupt, etc...
1181 config DEBUG_LOCKING_API_SELFTESTS
1182 bool "Locking API boot-time self-tests"
1183 depends on DEBUG_KERNEL
1185 Say Y here if you want the kernel to run a short self-test during
1186 bootup. The self-test checks whether common types of locking bugs
1187 are detected by debugging mechanisms or not. (if you disable
1188 lock debugging then those bugs wont be detected of course.)
1189 The following locking APIs are covered: spinlocks, rwlocks,
1192 config LOCK_TORTURE_TEST
1193 tristate "torture tests for locking"
1194 depends on DEBUG_KERNEL
1198 This option provides a kernel module that runs torture tests
1199 on kernel locking primitives. The kernel module may be built
1200 after the fact on the running kernel to be tested, if desired.
1202 Say Y here if you want kernel locking-primitive torture tests
1203 to be built into the kernel.
1204 Say M if you want these torture tests to build as a module.
1205 Say N if you are unsure.
1207 endmenu # lock debugging
1209 config TRACE_IRQFLAGS
1212 Enables hooks to interrupt enabling and disabling for
1213 either tracing or lock debugging.
1216 bool "Stack backtrace support"
1217 depends on STACKTRACE_SUPPORT
1219 This option causes the kernel to create a /proc/pid/stack for
1220 every process, showing its current stack trace.
1221 It is also used by various kernel debugging features that require
1222 stack trace generation.
1224 config DEBUG_KOBJECT
1225 bool "kobject debugging"
1226 depends on DEBUG_KERNEL
1228 If you say Y here, some extra kobject debugging messages will be sent
1231 config DEBUG_KOBJECT_RELEASE
1232 bool "kobject release debugging"
1233 depends on DEBUG_OBJECTS_TIMERS
1235 kobjects are reference counted objects. This means that their
1236 last reference count put is not predictable, and the kobject can
1237 live on past the point at which a driver decides to drop it's
1238 initial reference to the kobject gained on allocation. An
1239 example of this would be a struct device which has just been
1242 However, some buggy drivers assume that after such an operation,
1243 the memory backing the kobject can be immediately freed. This
1244 goes completely against the principles of a refcounted object.
1246 If you say Y here, the kernel will delay the release of kobjects
1247 on the last reference count to improve the visibility of this
1248 kind of kobject release bug.
1250 config HAVE_DEBUG_BUGVERBOSE
1253 config DEBUG_BUGVERBOSE
1254 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1255 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1258 Say Y here to make BUG() panics output the file name and line number
1259 of the BUG call as well as the EIP and oops trace. This aids
1260 debugging but costs about 70-100K of memory.
1263 bool "Debug linked list manipulation"
1264 depends on DEBUG_KERNEL
1266 Enable this to turn on extended checks in the linked-list
1271 config DEBUG_PI_LIST
1272 bool "Debug priority linked list manipulation"
1273 depends on DEBUG_KERNEL
1275 Enable this to turn on extended checks in the priority-ordered
1276 linked-list (plist) walking routines. This checks the entire
1277 list multiple times during each manipulation.
1282 bool "Debug SG table operations"
1283 depends on DEBUG_KERNEL
1285 Enable this to turn on checks on scatter-gather tables. This can
1286 help find problems with drivers that do not properly initialize
1291 config DEBUG_NOTIFIERS
1292 bool "Debug notifier call chains"
1293 depends on DEBUG_KERNEL
1295 Enable this to turn on sanity checking for notifier call chains.
1296 This is most useful for kernel developers to make sure that
1297 modules properly unregister themselves from notifier chains.
1298 This is a relatively cheap check but if you care about maximum
1301 config DEBUG_CREDENTIALS
1302 bool "Debug credential management"
1303 depends on DEBUG_KERNEL
1305 Enable this to turn on some debug checking for credential
1306 management. The additional code keeps track of the number of
1307 pointers from task_structs to any given cred struct, and checks to
1308 see that this number never exceeds the usage count of the cred
1311 Furthermore, if SELinux is enabled, this also checks that the
1312 security pointer in the cred struct is never seen to be invalid.
1316 menu "RCU Debugging"
1319 def_bool PROVE_LOCKING
1321 config PROVE_RCU_REPEATEDLY
1322 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1323 depends on PROVE_RCU
1326 By itself, PROVE_RCU will disable checking upon issuing the
1327 first warning (or "splat"). This feature prevents such
1328 disabling, allowing multiple RCU-lockdep warnings to be printed
1331 Say Y to allow multiple RCU-lockdep warnings per boot.
1333 Say N if you are unsure.
1335 config SPARSE_RCU_POINTER
1336 bool "RCU debugging: sparse-based checks for pointer usage"
1339 This feature enables the __rcu sparse annotation for
1340 RCU-protected pointers. This annotation will cause sparse
1341 to flag any non-RCU used of annotated pointers. This can be
1342 helpful when debugging RCU usage. Please note that this feature
1343 is not intended to enforce code cleanliness; it is instead merely
1346 Say Y to make sparse flag questionable use of RCU-protected pointers
1348 Say N if you are unsure.
1354 config RCU_TORTURE_TEST
1355 tristate "torture tests for RCU"
1356 depends on DEBUG_KERNEL
1362 This option provides a kernel module that runs torture tests
1363 on the RCU infrastructure. The kernel module may be built
1364 after the fact on the running kernel to be tested, if desired.
1366 Say Y here if you want RCU torture tests to be built into
1368 Say M if you want the RCU torture tests to build as a module.
1369 Say N if you are unsure.
1371 config RCU_TORTURE_TEST_RUNNABLE
1372 bool "torture tests for RCU runnable by default"
1373 depends on RCU_TORTURE_TEST = y
1376 This option provides a way to build the RCU torture tests
1377 directly into the kernel without them starting up at boot
1378 time. You can use /proc/sys/kernel/rcutorture_runnable
1379 to manually override this setting. This /proc file is
1380 available only when the RCU torture tests have been built
1383 Say Y here if you want the RCU torture tests to start during
1384 boot (you probably don't).
1385 Say N here if you want the RCU torture tests to start only
1386 after being manually enabled via /proc.
1388 config RCU_TORTURE_TEST_SLOW_PREINIT
1389 bool "Slow down RCU grace-period pre-initialization to expose races"
1390 depends on RCU_TORTURE_TEST
1392 This option delays grace-period pre-initialization (the
1393 propagation of CPU-hotplug changes up the rcu_node combining
1394 tree) for a few jiffies between initializing each pair of
1395 consecutive rcu_node structures. This helps to expose races
1396 involving grace-period pre-initialization, in other words, it
1397 makes your kernel less stable. It can also greatly increase
1398 grace-period latency, especially on systems with large numbers
1399 of CPUs. This is useful when torture-testing RCU, but in
1400 almost no other circumstance.
1402 Say Y here if you want your system to crash and hang more often.
1403 Say N if you want a sane system.
1405 config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1406 int "How much to slow down RCU grace-period pre-initialization"
1409 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1411 This option specifies the number of jiffies to wait between
1412 each rcu_node structure pre-initialization step.
1414 config RCU_TORTURE_TEST_SLOW_INIT
1415 bool "Slow down RCU grace-period initialization to expose races"
1416 depends on RCU_TORTURE_TEST
1418 This option delays grace-period initialization for a few
1419 jiffies between initializing each pair of consecutive
1420 rcu_node structures. This helps to expose races involving
1421 grace-period initialization, in other words, it makes your
1422 kernel less stable. It can also greatly increase grace-period
1423 latency, especially on systems with large numbers of CPUs.
1424 This is useful when torture-testing RCU, but in almost no
1427 Say Y here if you want your system to crash and hang more often.
1428 Say N if you want a sane system.
1430 config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1431 int "How much to slow down RCU grace-period initialization"
1434 depends on RCU_TORTURE_TEST_SLOW_INIT
1436 This option specifies the number of jiffies to wait between
1437 each rcu_node structure initialization.
1439 config RCU_TORTURE_TEST_SLOW_CLEANUP
1440 bool "Slow down RCU grace-period cleanup to expose races"
1441 depends on RCU_TORTURE_TEST
1443 This option delays grace-period cleanup for a few jiffies
1444 between cleaning up each pair of consecutive rcu_node
1445 structures. This helps to expose races involving grace-period
1446 cleanup, in other words, it makes your kernel less stable.
1447 It can also greatly increase grace-period latency, especially
1448 on systems with large numbers of CPUs. This is useful when
1449 torture-testing RCU, but in almost no other circumstance.
1451 Say Y here if you want your system to crash and hang more often.
1452 Say N if you want a sane system.
1454 config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1455 int "How much to slow down RCU grace-period cleanup"
1458 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1460 This option specifies the number of jiffies to wait between
1461 each rcu_node structure cleanup operation.
1463 config RCU_CPU_STALL_TIMEOUT
1464 int "RCU CPU stall timeout in seconds"
1465 depends on RCU_STALL_COMMON
1469 If a given RCU grace period extends more than the specified
1470 number of seconds, a CPU stall warning is printed. If the
1471 RCU grace period persists, additional CPU stall warnings are
1472 printed at more widely spaced intervals.
1474 config RCU_STALL_WATCHDOG_BITE
1475 bool "RCU stall induce watchdog bite"
1476 depends on RCU_STALL_COMMON && QCOM_WATCHDOG_V2
1478 Induce watchdog bite if RCU grace period extends more than
1479 specified no of seconds instead of just warning messages.
1480 This helps to collect ram dumps and cpu context for
1481 postmortem analysis. Generally if a given RCU grace period
1482 extends more than the specified number of seconds,
1483 a CPU stall warning is printed.
1486 bool "Enable tracing for RCU"
1487 depends on DEBUG_KERNEL
1490 This option provides tracing in RCU which presents stats
1491 in debugfs for debugging RCU implementation.
1493 Say Y here if you want to enable RCU tracing
1494 Say N if you are unsure.
1496 config RCU_EQS_DEBUG
1497 bool "Provide debugging asserts for adding NO_HZ support to an arch"
1498 depends on DEBUG_KERNEL
1500 This option provides consistency checks in RCU's handling of
1501 NO_HZ. These checks have proven quite helpful in detecting
1502 bugs in arch-specific NO_HZ code.
1504 Say N here if you need ultimate kernel/user switch latencies
1505 Say Y if you are unsure
1507 endmenu # "RCU Debugging"
1509 config DEBUG_BLOCK_EXT_DEVT
1510 bool "Force extended block device numbers and spread them"
1511 depends on DEBUG_KERNEL
1515 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1516 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1517 YOU ARE DOING. Distros, please enable this and fix whatever
1520 Conventionally, block device numbers are allocated from
1521 predetermined contiguous area. However, extended block area
1522 may introduce non-contiguous block device numbers. This
1523 option forces most block device numbers to be allocated from
1524 the extended space and spreads them to discover kernel or
1525 userland code paths which assume predetermined contiguous
1526 device number allocation.
1528 Note that turning on this debug option shuffles all the
1529 device numbers for all IDE and SCSI devices including libata
1530 ones, so root partition specified using device number
1531 directly (via rdev or root=MAJ:MIN) won't work anymore.
1532 Textual device names (root=/dev/sdXn) will continue to work.
1534 Say N if you are unsure.
1536 config NOTIFIER_ERROR_INJECTION
1537 tristate "Notifier error injection"
1538 depends on DEBUG_KERNEL
1541 This option provides the ability to inject artificial errors to
1542 specified notifier chain callbacks. It is useful to test the error
1543 handling of notifier call chain failures.
1547 config CPU_NOTIFIER_ERROR_INJECT
1548 tristate "CPU notifier error injection module"
1549 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1551 This option provides a kernel module that can be used to test
1552 the error handling of the cpu notifiers by injecting artificial
1553 errors to CPU notifier chain callbacks. It is controlled through
1554 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1556 If the notifier call chain should be failed with some events
1557 notified, write the error code to "actions/<notifier event>/error".
1559 Example: Inject CPU offline error (-1 == -EPERM)
1561 # cd /sys/kernel/debug/notifier-error-inject/cpu
1562 # echo -1 > actions/CPU_DOWN_PREPARE/error
1563 # echo 0 > /sys/devices/system/cpu/cpu1/online
1564 bash: echo: write error: Operation not permitted
1566 To compile this code as a module, choose M here: the module will
1567 be called cpu-notifier-error-inject.
1571 config PM_NOTIFIER_ERROR_INJECT
1572 tristate "PM notifier error injection module"
1573 depends on PM && NOTIFIER_ERROR_INJECTION
1574 default m if PM_DEBUG
1576 This option provides the ability to inject artificial errors to
1577 PM notifier chain callbacks. It is controlled through debugfs
1578 interface /sys/kernel/debug/notifier-error-inject/pm
1580 If the notifier call chain should be failed with some events
1581 notified, write the error code to "actions/<notifier event>/error".
1583 Example: Inject PM suspend error (-12 = -ENOMEM)
1585 # cd /sys/kernel/debug/notifier-error-inject/pm/
1586 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1587 # echo mem > /sys/power/state
1588 bash: echo: write error: Cannot allocate memory
1590 To compile this code as a module, choose M here: the module will
1591 be called pm-notifier-error-inject.
1595 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1596 tristate "OF reconfig notifier error injection module"
1597 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1599 This option provides the ability to inject artificial errors to
1600 OF reconfig notifier chain callbacks. It is controlled
1601 through debugfs interface under
1602 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1604 If the notifier call chain should be failed with some events
1605 notified, write the error code to "actions/<notifier event>/error".
1607 To compile this code as a module, choose M here: the module will
1608 be called of-reconfig-notifier-error-inject.
1612 config FAULT_INJECTION
1613 bool "Fault-injection framework"
1614 depends on DEBUG_KERNEL
1616 Provide fault-injection framework.
1617 For more details, see Documentation/fault-injection/.
1620 bool "Fault-injection capability for kmalloc"
1621 depends on FAULT_INJECTION
1622 depends on SLAB || SLUB
1624 Provide fault-injection capability for kmalloc.
1626 config FAIL_PAGE_ALLOC
1627 bool "Fault-injection capabilitiy for alloc_pages()"
1628 depends on FAULT_INJECTION
1630 Provide fault-injection capability for alloc_pages().
1632 config FAIL_MAKE_REQUEST
1633 bool "Fault-injection capability for disk IO"
1634 depends on FAULT_INJECTION && BLOCK
1636 Provide fault-injection capability for disk IO.
1638 config FAIL_IO_TIMEOUT
1639 bool "Fault-injection capability for faking disk interrupts"
1640 depends on FAULT_INJECTION && BLOCK
1642 Provide fault-injection capability on end IO handling. This
1643 will make the block layer "forget" an interrupt as configured,
1644 thus exercising the error handling.
1646 Only works with drivers that use the generic timeout handling,
1647 for others it wont do anything.
1649 config FAIL_MMC_REQUEST
1650 bool "Fault-injection capability for MMC IO"
1652 depends on FAULT_INJECTION && MMC
1654 Provide fault-injection capability for MMC IO.
1655 This will make the mmc core return data errors. This is
1656 useful to test the error handling in the mmc block device
1657 and to test how the mmc host driver handles retries from
1660 config UFS_FAULT_INJECTION
1661 bool "Fault-injection capability for UFS IO"
1663 depends on FAULT_INJECTION && SCSI_UFSHCD
1665 Provide fault-injection capability for UFS IO.
1666 This will make the UFS host controller driver to randomly
1667 abort ongoing commands in the host controller, update OCS
1668 field according to the injected fatal error and can also
1669 forcefully hang the command indefinitely till upper layer
1670 timeout occurs. This is useful to test error handling in
1671 the UFS contoller driver and test how the driver handles
1672 the retries from block/SCSI mid layer.
1675 bool "Fault-injection capability for futexes"
1677 depends on FAULT_INJECTION && FUTEX
1679 Provide fault-injection capability for futexes.
1681 config FAULT_INJECTION_DEBUG_FS
1682 bool "Debugfs entries for fault-injection capabilities"
1683 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1685 Enable configuration of fault-injection capabilities via debugfs.
1687 config FAULT_INJECTION_STACKTRACE_FILTER
1688 bool "stacktrace filter for fault-injection capabilities"
1689 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1692 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1694 Provide stacktrace filter for fault-injection capabilities
1697 bool "Latency measuring infrastructure"
1698 depends on HAVE_LATENCYTOP_SUPPORT
1699 depends on DEBUG_KERNEL
1700 depends on STACKTRACE_SUPPORT
1702 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1709 Enable this option if you want to use the LatencyTOP tool
1710 to find out which userspace is blocking on what kernel operations.
1712 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1715 config DEBUG_STRICT_USER_COPY_CHECKS
1716 bool "Strict user copy size checks"
1717 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1718 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1720 Enabling this option turns a certain set of sanity checks for user
1721 copy operations into compile time failures.
1723 The copy_from_user() etc checks are there to help test if there
1724 are sufficient security checks on the length argument of
1725 the copy operation, by having gcc prove that the argument is
1730 source kernel/trace/Kconfig
1732 menu "Runtime Testing"
1735 tristate "Linux Kernel Dump Test Tool Module"
1740 This module enables testing of the different dumping mechanisms by
1741 inducing system failures at predefined crash points.
1742 If you don't need it: say N
1743 Choose M here to compile this code as a module. The module will be
1746 Documentation on how to use the module can be found in
1747 Documentation/fault-injection/provoke-crashes.txt
1749 config TEST_LIST_SORT
1750 bool "Linked list sorting test"
1751 depends on DEBUG_KERNEL
1753 Enable this to turn on 'list_sort()' function test. This test is
1754 executed only once during system boot, so affects only boot time.
1758 config KPROBES_SANITY_TEST
1759 bool "Kprobes sanity tests"
1760 depends on DEBUG_KERNEL
1764 This option provides for testing basic kprobes functionality on
1765 boot. A sample kprobe, jprobe and kretprobe are inserted and
1766 verified for functionality.
1768 Say N if you are unsure.
1770 config BACKTRACE_SELF_TEST
1771 tristate "Self test for the backtrace code"
1772 depends on DEBUG_KERNEL
1775 This option provides a kernel module that can be used to test
1776 the kernel stack backtrace code. This option is not useful
1777 for distributions or general kernels, but only for kernel
1778 developers working on architecture code.
1780 Note that if you want to also test saved backtraces, you will
1781 have to enable STACKTRACE as well.
1783 Say N if you are unsure.
1786 tristate "Red-Black tree test"
1787 depends on DEBUG_KERNEL
1789 A benchmark measuring the performance of the rbtree library.
1790 Also includes rbtree invariant checks.
1792 config INTERVAL_TREE_TEST
1793 tristate "Interval tree test"
1794 depends on m && DEBUG_KERNEL
1795 select INTERVAL_TREE
1797 A benchmark measuring the performance of the interval tree library
1800 tristate "Per cpu operations test"
1801 depends on m && DEBUG_KERNEL
1803 Enable this option to build test module which validates per-cpu
1808 config ATOMIC64_SELFTEST
1809 bool "Perform an atomic64_t self-test at boot"
1811 Enable this option to test the atomic64_t functions at boot.
1815 config ASYNC_RAID6_TEST
1816 tristate "Self test for hardware accelerated raid6 recovery"
1817 depends on ASYNC_RAID6_RECOV
1820 This is a one-shot self test that permutes through the
1821 recovery of all the possible two disk failure scenarios for a
1822 N-disk array. Recovery is performed with the asynchronous
1823 raid6 recovery routines, and will optionally use an offload
1824 engine if one is available.
1829 tristate "Test functions located in the hexdump module at runtime"
1831 config TEST_STRING_HELPERS
1832 tristate "Test functions located in the string_helpers module at runtime"
1835 tristate "Test kstrto*() family of functions at runtime"
1838 tristate "Test printf() family of functions at runtime"
1840 config TEST_RHASHTABLE
1841 tristate "Perform selftest on resizable hash table"
1844 Enable this option to test the rhashtable functions at boot.
1849 tristate "Perform selftest on hash functions"
1852 Enable this option to test the kernel's siphash (<linux/siphash.h>)
1853 hash functions on boot (or module load).
1855 This is intended to help people writing architecture-specific
1856 optimized versions. If unsure, say N.
1858 endmenu # runtime tests
1860 config PROVIDE_OHCI1394_DMA_INIT
1861 bool "Remote debugging over FireWire early on boot"
1862 depends on PCI && X86
1864 If you want to debug problems which hang or crash the kernel early
1865 on boot and the crashing machine has a FireWire port, you can use
1866 this feature to remotely access the memory of the crashed machine
1867 over FireWire. This employs remote DMA as part of the OHCI1394
1868 specification which is now the standard for FireWire controllers.
1870 With remote DMA, you can monitor the printk buffer remotely using
1871 firescope and access all memory below 4GB using fireproxy from gdb.
1872 Even controlling a kernel debugger is possible using remote DMA.
1876 If ohci1394_dma=early is used as boot parameter, it will initialize
1877 all OHCI1394 controllers which are found in the PCI config space.
1879 As all changes to the FireWire bus such as enabling and disabling
1880 devices cause a bus reset and thereby disable remote DMA for all
1881 devices, be sure to have the cable plugged and FireWire enabled on
1882 the debugging host before booting the debug target for debugging.
1884 This code (~1k) is freed after boot. By then, the firewire stack
1885 in charge of the OHCI-1394 controllers should be used instead.
1887 See Documentation/debugging-via-ohci1394.txt for more information.
1890 bool "Build targets in Documentation/ tree"
1891 depends on HEADERS_CHECK
1893 This option attempts to build objects from the source files in the
1894 kernel Documentation/ tree.
1896 Say N if you are unsure.
1898 config DMA_API_DEBUG
1899 bool "Enable debugging of DMA-API usage"
1900 depends on HAVE_DMA_API_DEBUG
1902 Enable this option to debug the use of the DMA API by device drivers.
1903 With this option you will be able to detect common bugs in device
1904 drivers like double-freeing of DMA mappings or freeing mappings that
1905 were never allocated.
1907 This also attempts to catch cases where a page owned by DMA is
1908 accessed by the cpu in a way that could cause data corruption. For
1909 example, this enables cow_user_page() to check that the source page is
1912 This option causes a performance degradation. Use only if you want to
1913 debug device drivers and dma interactions.
1918 tristate "Test module loading with 'hello world' module"
1922 This builds the "test_module" module that emits "Hello, world"
1923 on printk when loaded. It is designed to be used for basic
1924 evaluation of the module loading subsystem (for example when
1925 validating module verification). It lacks any extra dependencies,
1926 and will not normally be loaded by the system unless explicitly
1931 config TEST_USER_COPY
1932 tristate "Test user/kernel boundary protections"
1936 This builds the "test_user_copy" module that runs sanity checks
1937 on the copy_to/from_user infrastructure, making sure basic
1938 user/kernel boundary testing is working. If it fails to load,
1939 a regression has been detected in the user/kernel memory boundary
1945 tristate "Test BPF filter functionality"
1949 This builds the "test_bpf" module that runs various test vectors
1950 against the BPF interpreter or BPF JIT compiler depending on the
1951 current setting. This is in particular useful for BPF JIT compiler
1952 development, but also to run regression tests against changes in
1953 the interpreter code. It also enables test stubs for eBPF maps and
1954 verifier used by user space verifier testsuite.
1958 config TEST_FIRMWARE
1959 tristate "Test firmware loading via userspace interface"
1961 depends on FW_LOADER
1963 This builds the "test_firmware" module that creates a userspace
1964 interface for testing firmware loading. This can be used to
1965 control the triggering of firmware loading without needing an
1966 actual firmware-using device. The contents can be rechecked by
1972 tristate "udelay test driver"
1975 This builds the "udelay_test" module that helps to make sure
1976 that udelay() is working properly.
1982 depends on HAVE_MEMBLOCK
1984 This option adds a kernel parameter 'memtest', which allows memtest
1986 memtest=0, mean disabled; -- default
1987 memtest=1, mean do 1 test pattern;
1989 memtest=17, mean do 17 test patterns.
1990 If you are unsure how to answer this question, answer N.
1992 config MEMTEST_ENABLE_DEFAULT
1993 int "Enable Memtest pattern test by default? (0-17)"
1998 This option helps to select Memtest to be enabled through
1999 kernel defconfig options. Alternatively it can be enabled
2000 using memtest=<patterns> kernel command line.
2002 Default value is kept as "0" so that it is kept as disabled.
2003 To enable enter any value between 1-17 range.
2005 config TEST_STATIC_KEYS
2006 tristate "Test static keys"
2010 Test the static key interfaces.
2014 config PANIC_ON_DATA_CORRUPTION
2015 bool "Cause a Kernel Panic When Data Corruption is detected"
2017 Select this option to upgrade warnings for potentially
2018 recoverable data corruption scenarios to system-halting panics,
2019 for easier detection and debug.
2021 config BUG_ON_DATA_CORRUPTION
2022 bool "Trigger a BUG when data corruption is detected"
2023 select CONFIG_DEBUG_LIST
2025 Select this option if the kernel should BUG when it encounters
2026 data corruption in kernel memory structures when they get checked
2032 bool "Treat all compile warnings as errors"
2035 Select this option to set compiler warnings as errors,
2036 to prevent easily-fixable problems from creeping into
2041 source "samples/Kconfig"
2043 source "lib/Kconfig.kgdb"
2045 source "lib/Kconfig.ubsan"
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