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.
574 config DEBUG_VM_PGFLAGS
575 bool "Debug page-flags operations"
578 Enables extra validation on page flags operations.
583 bool "Debug VM translations"
584 depends on DEBUG_KERNEL && X86
586 Enable some costly sanity checks in virtual to page code. This can
587 catch mistakes with virt_to_page() and friends.
591 config DEBUG_NOMMU_REGIONS
592 bool "Debug the global anon/private NOMMU mapping region tree"
593 depends on DEBUG_KERNEL && !MMU
595 This option causes the global tree of anonymous and private mapping
596 regions to be regularly checked for invalid topology.
598 config DEBUG_MEMORY_INIT
599 bool "Debug memory initialisation" if EXPERT
602 Enable this for additional checks during memory initialisation.
603 The sanity checks verify aspects of the VM such as the memory model
604 and other information provided by the architecture. Verbose
605 information will be printed at KERN_DEBUG loglevel depending
606 on the mminit_loglevel= command-line option.
610 config MEMORY_NOTIFIER_ERROR_INJECT
611 tristate "Memory hotplug notifier error injection module"
612 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
614 This option provides the ability to inject artificial errors to
615 memory hotplug notifier chain callbacks. It is controlled through
616 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
618 If the notifier call chain should be failed with some events
619 notified, write the error code to "actions/<notifier event>/error".
621 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
623 # cd /sys/kernel/debug/notifier-error-inject/memory
624 # echo -12 > actions/MEM_GOING_OFFLINE/error
625 # echo offline > /sys/devices/system/memory/memoryXXX/state
626 bash: echo: write error: Cannot allocate memory
628 To compile this code as a module, choose M here: the module will
629 be called memory-notifier-error-inject.
633 config DEBUG_PER_CPU_MAPS
634 bool "Debug access to per_cpu maps"
635 depends on DEBUG_KERNEL
638 Say Y to verify that the per_cpu map being accessed has
639 been set up. This adds a fair amount of code to kernel memory
640 and decreases performance.
645 bool "Highmem debugging"
646 depends on DEBUG_KERNEL && HIGHMEM
648 This option enables additional error checking for high memory
649 systems. Disable for production systems.
651 config HAVE_DEBUG_STACKOVERFLOW
654 config DEBUG_STACKOVERFLOW
655 bool "Check for stack overflows"
656 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
658 Say Y here if you want to check for overflows of kernel, IRQ
659 and exception stacks (if your architecture uses them). This
660 option will show detailed messages if free stack space drops
661 below a certain limit.
663 These kinds of bugs usually occur when call-chains in the
664 kernel get too deep, especially when interrupts are
667 Use this in cases where you see apparently random memory
668 corruption, especially if it appears in 'struct thread_info'
670 If in doubt, say "N".
672 source "lib/Kconfig.kmemcheck"
674 source "lib/Kconfig.kasan"
676 endmenu # "Memory Debugging"
679 bool "Debug shared IRQ handlers"
680 depends on DEBUG_KERNEL
682 Enable this to generate a spurious interrupt as soon as a shared
683 interrupt handler is registered, and just before one is deregistered.
684 Drivers ought to be able to handle interrupts coming in at those
685 points; some don't and need to be caught.
687 menu "Debug Lockups and Hangs"
689 config LOCKUP_DETECTOR
690 bool "Detect Hard and Soft Lockups"
691 depends on DEBUG_KERNEL && !S390
693 Say Y here to enable the kernel to act as a watchdog to detect
694 hard and soft lockups.
696 Softlockups are bugs that cause the kernel to loop in kernel
697 mode for more than 20 seconds, without giving other tasks a
698 chance to run. The current stack trace is displayed upon
699 detection and the system will stay locked up.
701 Hardlockups are bugs that cause the CPU to loop in kernel mode
702 for more than 10 seconds, without letting other interrupts have a
703 chance to run. The current stack trace is displayed upon detection
704 and the system will stay locked up.
706 The overhead should be minimal. A periodic hrtimer runs to
707 generate interrupts and kick the watchdog task every 4 seconds.
708 An NMI is generated every 10 seconds or so to check for hardlockups.
710 The frequency of hrtimer and NMI events and the soft and hard lockup
711 thresholds can be controlled through the sysctl watchdog_thresh.
713 config HARDLOCKUP_DETECTOR
715 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
716 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
718 config BOOTPARAM_HARDLOCKUP_PANIC
719 bool "Panic (Reboot) On Hard Lockups"
720 depends on HARDLOCKUP_DETECTOR
722 Say Y here to enable the kernel to panic on "hard lockups",
723 which are bugs that cause the kernel to loop in kernel
724 mode with interrupts disabled for more than 10 seconds (configurable
725 using the watchdog_thresh sysctl).
729 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
731 depends on HARDLOCKUP_DETECTOR
733 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
734 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
736 config BOOTPARAM_SOFTLOCKUP_PANIC
737 bool "Panic (Reboot) On Soft Lockups"
738 depends on LOCKUP_DETECTOR
740 Say Y here to enable the kernel to panic on "soft lockups",
741 which are bugs that cause the kernel to loop in kernel
742 mode for more than 20 seconds (configurable using the watchdog_thresh
743 sysctl), without giving other tasks a chance to run.
745 The panic can be used in combination with panic_timeout,
746 to cause the system to reboot automatically after a
747 lockup has been detected. This feature is useful for
748 high-availability systems that have uptime guarantees and
749 where a lockup must be resolved ASAP.
753 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
755 depends on LOCKUP_DETECTOR
757 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
758 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
760 config DETECT_HUNG_TASK
761 bool "Detect Hung Tasks"
762 depends on DEBUG_KERNEL
763 default LOCKUP_DETECTOR
765 Say Y here to enable the kernel to detect "hung tasks",
766 which are bugs that cause the task to be stuck in
767 uninterruptible "D" state indefinitiley.
769 When a hung task is detected, the kernel will print the
770 current stack trace (which you should report), but the
771 task will stay in uninterruptible state. If lockdep is
772 enabled then all held locks will also be reported. This
773 feature has negligible overhead.
775 config DEFAULT_HUNG_TASK_TIMEOUT
776 int "Default timeout for hung task detection (in seconds)"
777 depends on DETECT_HUNG_TASK
780 This option controls the default timeout (in seconds) used
781 to determine when a task has become non-responsive and should
784 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
785 sysctl or by writing a value to
786 /proc/sys/kernel/hung_task_timeout_secs.
788 A timeout of 0 disables the check. The default is two minutes.
789 Keeping the default should be fine in most cases.
791 config BOOTPARAM_HUNG_TASK_PANIC
792 bool "Panic (Reboot) On Hung Tasks"
793 depends on DETECT_HUNG_TASK
795 Say Y here to enable the kernel to panic on "hung tasks",
796 which are bugs that cause the kernel to leave a task stuck
797 in uninterruptible "D" state.
799 The panic can be used in combination with panic_timeout,
800 to cause the system to reboot automatically after a
801 hung task has been detected. This feature is useful for
802 high-availability systems that have uptime guarantees and
803 where a hung tasks must be resolved ASAP.
807 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
809 depends on DETECT_HUNG_TASK
811 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
812 default 1 if BOOTPARAM_HUNG_TASK_PANIC
814 endmenu # "Debug lockups and hangs"
819 Say Y here to enable the kernel to panic when it oopses. This
820 has the same effect as setting oops=panic on the kernel command
823 This feature is useful to ensure that the kernel does not do
824 anything erroneous after an oops which could result in data
825 corruption or other issues.
829 config PANIC_ON_OOPS_VALUE
832 default 0 if !PANIC_ON_OOPS
833 default 1 if PANIC_ON_OOPS
839 Set the timeout value (in seconds) until a reboot occurs when the
840 the kernel panics. If n = 0, then we wait forever. A timeout
841 value n > 0 will wait n seconds before rebooting, while a timeout
842 value n < 0 will reboot immediately.
845 bool "Collect scheduler debugging info"
846 depends on DEBUG_KERNEL && PROC_FS
849 If you say Y here, the /proc/sched_debug file will be provided
850 that can help debug the scheduler. The runtime overhead of this
858 bool "Collect scheduler statistics"
859 depends on DEBUG_KERNEL && PROC_FS
862 If you say Y here, additional code will be inserted into the
863 scheduler and related routines to collect statistics about
864 scheduler behavior and provide them in /proc/schedstat. These
865 stats may be useful for both tuning and debugging the scheduler
866 If you aren't debugging the scheduler or trying to tune a specific
867 application, you can say N to avoid the very slight overhead
870 config SCHED_STACK_END_CHECK
871 bool "Detect stack corruption on calls to schedule()"
872 depends on DEBUG_KERNEL
875 This option checks for a stack overrun on calls to schedule().
876 If the stack end location is found to be over written always panic as
877 the content of the corrupted region can no longer be trusted.
878 This is to ensure no erroneous behaviour occurs which could result in
879 data corruption or a sporadic crash at a later stage once the region
880 is examined. The runtime overhead introduced is minimal.
882 config DEBUG_TIMEKEEPING
883 bool "Enable extra timekeeping sanity checking"
885 This option will enable additional timekeeping sanity checks
886 which may be helpful when diagnosing issues where timekeeping
887 problems are suspected.
889 This may include checks in the timekeeping hotpaths, so this
890 option may have a (very small) performance impact to some
896 bool "Collect kernel timers statistics"
897 depends on DEBUG_KERNEL && PROC_FS
899 If you say Y here, additional code will be inserted into the
900 timer routines to collect statistics about kernel timers being
901 reprogrammed. The statistics can be read from /proc/timer_stats.
902 The statistics collection is started by writing 1 to /proc/timer_stats,
903 writing 0 stops it. This feature is useful to collect information
904 about timer usage patterns in kernel and userspace. This feature
905 is lightweight if enabled in the kernel config but not activated
906 (it defaults to deactivated on bootup and will only be activated
907 if some application like powertop activates it explicitly).
910 bool "Debug preemptible kernel"
911 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
914 If you say Y here then the kernel will use a debug variant of the
915 commonly used smp_processor_id() function and will print warnings
916 if kernel code uses it in a preemption-unsafe way. Also, the kernel
917 will detect preemption count underflows.
919 menu "Lock Debugging (spinlocks, mutexes, etc...)"
921 config DEBUG_RT_MUTEXES
922 bool "RT Mutex debugging, deadlock detection"
923 depends on DEBUG_KERNEL && RT_MUTEXES
925 This allows rt mutex semantics violations and rt mutex related
926 deadlocks (lockups) to be detected and reported automatically.
928 config DEBUG_SPINLOCK
929 bool "Spinlock and rw-lock debugging: basic checks"
930 depends on DEBUG_KERNEL
931 select UNINLINE_SPIN_UNLOCK
933 Say Y here and build SMP to catch missing spinlock initialization
934 and certain other kinds of spinlock errors commonly made. This is
935 best used in conjunction with the NMI watchdog so that spinlock
936 deadlocks are also debuggable.
939 bool "Mutex debugging: basic checks"
940 depends on DEBUG_KERNEL
942 This feature allows mutex semantics violations to be detected and
945 config DEBUG_WW_MUTEX_SLOWPATH
946 bool "Wait/wound mutex debugging: Slowpath testing"
947 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
948 select DEBUG_LOCK_ALLOC
949 select DEBUG_SPINLOCK
952 This feature enables slowpath testing for w/w mutex users by
953 injecting additional -EDEADLK wound/backoff cases. Together with
954 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
955 will test all possible w/w mutex interface abuse with the
956 exception of simply not acquiring all the required locks.
957 Note that this feature can introduce significant overhead, so
958 it really should not be enabled in a production or distro kernel,
959 even a debug kernel. If you are a driver writer, enable it. If
960 you are a distro, do not.
962 config DEBUG_LOCK_ALLOC
963 bool "Lock debugging: detect incorrect freeing of live locks"
964 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
965 select DEBUG_SPINLOCK
969 This feature will check whether any held lock (spinlock, rwlock,
970 mutex or rwsem) is incorrectly freed by the kernel, via any of the
971 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
972 vfree(), etc.), whether a live lock is incorrectly reinitialized via
973 spin_lock_init()/mutex_init()/etc., or whether there is any lock
974 held during task exit.
977 bool "Lock debugging: prove locking correctness"
978 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
980 select DEBUG_SPINLOCK
982 select DEBUG_LOCK_ALLOC
983 select TRACE_IRQFLAGS
986 This feature enables the kernel to prove that all locking
987 that occurs in the kernel runtime is mathematically
988 correct: that under no circumstance could an arbitrary (and
989 not yet triggered) combination of observed locking
990 sequences (on an arbitrary number of CPUs, running an
991 arbitrary number of tasks and interrupt contexts) cause a
994 In short, this feature enables the kernel to report locking
995 related deadlocks before they actually occur.
997 The proof does not depend on how hard and complex a
998 deadlock scenario would be to trigger: how many
999 participant CPUs, tasks and irq-contexts would be needed
1000 for it to trigger. The proof also does not depend on
1001 timing: if a race and a resulting deadlock is possible
1002 theoretically (no matter how unlikely the race scenario
1003 is), it will be proven so and will immediately be
1004 reported by the kernel (once the event is observed that
1005 makes the deadlock theoretically possible).
1007 If a deadlock is impossible (i.e. the locking rules, as
1008 observed by the kernel, are mathematically correct), the
1009 kernel reports nothing.
1011 NOTE: this feature can also be enabled for rwlocks, mutexes
1012 and rwsems - in which case all dependencies between these
1013 different locking variants are observed and mapped too, and
1014 the proof of observed correctness is also maintained for an
1015 arbitrary combination of these separate locking variants.
1017 For more details, see Documentation/locking/lockdep-design.txt.
1021 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1023 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
1028 bool "Lock usage statistics"
1029 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1031 select DEBUG_SPINLOCK
1032 select DEBUG_MUTEXES
1033 select DEBUG_LOCK_ALLOC
1036 This feature enables tracking lock contention points
1038 For more details, see Documentation/locking/lockstat.txt
1040 This also enables lock events required by "perf lock",
1042 If you want to use "perf lock", you also need to turn on
1043 CONFIG_EVENT_TRACING.
1045 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1046 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1048 config DEBUG_LOCKDEP
1049 bool "Lock dependency engine debugging"
1050 depends on DEBUG_KERNEL && LOCKDEP
1052 If you say Y here, the lock dependency engine will do
1053 additional runtime checks to debug itself, at the price
1054 of more runtime overhead.
1056 config DEBUG_ATOMIC_SLEEP
1057 bool "Sleep inside atomic section checking"
1058 select PREEMPT_COUNT
1059 depends on DEBUG_KERNEL
1061 If you say Y here, various routines which may sleep will become very
1062 noisy if they are called inside atomic sections: when a spinlock is
1063 held, inside an rcu read side critical section, inside preempt disabled
1064 sections, inside an interrupt, etc...
1066 config DEBUG_LOCKING_API_SELFTESTS
1067 bool "Locking API boot-time self-tests"
1068 depends on DEBUG_KERNEL
1070 Say Y here if you want the kernel to run a short self-test during
1071 bootup. The self-test checks whether common types of locking bugs
1072 are detected by debugging mechanisms or not. (if you disable
1073 lock debugging then those bugs wont be detected of course.)
1074 The following locking APIs are covered: spinlocks, rwlocks,
1077 config LOCK_TORTURE_TEST
1078 tristate "torture tests for locking"
1079 depends on DEBUG_KERNEL
1083 This option provides a kernel module that runs torture tests
1084 on kernel locking primitives. The kernel module may be built
1085 after the fact on the running kernel to be tested, if desired.
1087 Say Y here if you want kernel locking-primitive torture tests
1088 to be built into the kernel.
1089 Say M if you want these torture tests to build as a module.
1090 Say N if you are unsure.
1092 endmenu # lock debugging
1094 config TRACE_IRQFLAGS
1097 Enables hooks to interrupt enabling and disabling for
1098 either tracing or lock debugging.
1101 bool "Stack backtrace support"
1102 depends on STACKTRACE_SUPPORT
1104 This option causes the kernel to create a /proc/pid/stack for
1105 every process, showing its current stack trace.
1106 It is also used by various kernel debugging features that require
1107 stack trace generation.
1109 config DEBUG_KOBJECT
1110 bool "kobject debugging"
1111 depends on DEBUG_KERNEL
1113 If you say Y here, some extra kobject debugging messages will be sent
1116 config DEBUG_KOBJECT_RELEASE
1117 bool "kobject release debugging"
1118 depends on DEBUG_OBJECTS_TIMERS
1120 kobjects are reference counted objects. This means that their
1121 last reference count put is not predictable, and the kobject can
1122 live on past the point at which a driver decides to drop it's
1123 initial reference to the kobject gained on allocation. An
1124 example of this would be a struct device which has just been
1127 However, some buggy drivers assume that after such an operation,
1128 the memory backing the kobject can be immediately freed. This
1129 goes completely against the principles of a refcounted object.
1131 If you say Y here, the kernel will delay the release of kobjects
1132 on the last reference count to improve the visibility of this
1133 kind of kobject release bug.
1135 config HAVE_DEBUG_BUGVERBOSE
1138 config DEBUG_BUGVERBOSE
1139 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1140 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1143 Say Y here to make BUG() panics output the file name and line number
1144 of the BUG call as well as the EIP and oops trace. This aids
1145 debugging but costs about 70-100K of memory.
1148 bool "Debug linked list manipulation"
1149 depends on DEBUG_KERNEL
1151 Enable this to turn on extended checks in the linked-list
1156 config DEBUG_PI_LIST
1157 bool "Debug priority linked list manipulation"
1158 depends on DEBUG_KERNEL
1160 Enable this to turn on extended checks in the priority-ordered
1161 linked-list (plist) walking routines. This checks the entire
1162 list multiple times during each manipulation.
1167 bool "Debug SG table operations"
1168 depends on DEBUG_KERNEL
1170 Enable this to turn on checks on scatter-gather tables. This can
1171 help find problems with drivers that do not properly initialize
1176 config DEBUG_NOTIFIERS
1177 bool "Debug notifier call chains"
1178 depends on DEBUG_KERNEL
1180 Enable this to turn on sanity checking for notifier call chains.
1181 This is most useful for kernel developers to make sure that
1182 modules properly unregister themselves from notifier chains.
1183 This is a relatively cheap check but if you care about maximum
1186 config DEBUG_CREDENTIALS
1187 bool "Debug credential management"
1188 depends on DEBUG_KERNEL
1190 Enable this to turn on some debug checking for credential
1191 management. The additional code keeps track of the number of
1192 pointers from task_structs to any given cred struct, and checks to
1193 see that this number never exceeds the usage count of the cred
1196 Furthermore, if SELinux is enabled, this also checks that the
1197 security pointer in the cred struct is never seen to be invalid.
1201 menu "RCU Debugging"
1204 def_bool PROVE_LOCKING
1206 config PROVE_RCU_REPEATEDLY
1207 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1208 depends on PROVE_RCU
1211 By itself, PROVE_RCU will disable checking upon issuing the
1212 first warning (or "splat"). This feature prevents such
1213 disabling, allowing multiple RCU-lockdep warnings to be printed
1216 Say Y to allow multiple RCU-lockdep warnings per boot.
1218 Say N if you are unsure.
1220 config SPARSE_RCU_POINTER
1221 bool "RCU debugging: sparse-based checks for pointer usage"
1224 This feature enables the __rcu sparse annotation for
1225 RCU-protected pointers. This annotation will cause sparse
1226 to flag any non-RCU used of annotated pointers. This can be
1227 helpful when debugging RCU usage. Please note that this feature
1228 is not intended to enforce code cleanliness; it is instead merely
1231 Say Y to make sparse flag questionable use of RCU-protected pointers
1233 Say N if you are unsure.
1239 config RCU_TORTURE_TEST
1240 tristate "torture tests for RCU"
1241 depends on DEBUG_KERNEL
1247 This option provides a kernel module that runs torture tests
1248 on the RCU infrastructure. The kernel module may be built
1249 after the fact on the running kernel to be tested, if desired.
1251 Say Y here if you want RCU torture tests to be built into
1253 Say M if you want the RCU torture tests to build as a module.
1254 Say N if you are unsure.
1256 config RCU_TORTURE_TEST_RUNNABLE
1257 bool "torture tests for RCU runnable by default"
1258 depends on RCU_TORTURE_TEST = y
1261 This option provides a way to build the RCU torture tests
1262 directly into the kernel without them starting up at boot
1263 time. You can use /proc/sys/kernel/rcutorture_runnable
1264 to manually override this setting. This /proc file is
1265 available only when the RCU torture tests have been built
1268 Say Y here if you want the RCU torture tests to start during
1269 boot (you probably don't).
1270 Say N here if you want the RCU torture tests to start only
1271 after being manually enabled via /proc.
1273 config RCU_TORTURE_TEST_SLOW_PREINIT
1274 bool "Slow down RCU grace-period pre-initialization to expose races"
1275 depends on RCU_TORTURE_TEST
1277 This option delays grace-period pre-initialization (the
1278 propagation of CPU-hotplug changes up the rcu_node combining
1279 tree) for a few jiffies between initializing each pair of
1280 consecutive rcu_node structures. This helps to expose races
1281 involving grace-period pre-initialization, in other words, it
1282 makes your kernel less stable. It can also greatly increase
1283 grace-period latency, especially on systems with large numbers
1284 of CPUs. This is useful when torture-testing RCU, but in
1285 almost no other circumstance.
1287 Say Y here if you want your system to crash and hang more often.
1288 Say N if you want a sane system.
1290 config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1291 int "How much to slow down RCU grace-period pre-initialization"
1294 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1296 This option specifies the number of jiffies to wait between
1297 each rcu_node structure pre-initialization step.
1299 config RCU_TORTURE_TEST_SLOW_INIT
1300 bool "Slow down RCU grace-period initialization to expose races"
1301 depends on RCU_TORTURE_TEST
1303 This option delays grace-period initialization for a few
1304 jiffies between initializing each pair of consecutive
1305 rcu_node structures. This helps to expose races involving
1306 grace-period initialization, in other words, it makes your
1307 kernel less stable. It can also greatly increase grace-period
1308 latency, especially on systems with large numbers of CPUs.
1309 This is useful when torture-testing RCU, but in almost no
1312 Say Y here if you want your system to crash and hang more often.
1313 Say N if you want a sane system.
1315 config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1316 int "How much to slow down RCU grace-period initialization"
1319 depends on RCU_TORTURE_TEST_SLOW_INIT
1321 This option specifies the number of jiffies to wait between
1322 each rcu_node structure initialization.
1324 config RCU_TORTURE_TEST_SLOW_CLEANUP
1325 bool "Slow down RCU grace-period cleanup to expose races"
1326 depends on RCU_TORTURE_TEST
1328 This option delays grace-period cleanup for a few jiffies
1329 between cleaning up each pair of consecutive rcu_node
1330 structures. This helps to expose races involving grace-period
1331 cleanup, in other words, it makes your kernel less stable.
1332 It can also greatly increase grace-period latency, especially
1333 on systems with large numbers of CPUs. This is useful when
1334 torture-testing RCU, but in almost no other circumstance.
1336 Say Y here if you want your system to crash and hang more often.
1337 Say N if you want a sane system.
1339 config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1340 int "How much to slow down RCU grace-period cleanup"
1343 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1345 This option specifies the number of jiffies to wait between
1346 each rcu_node structure cleanup operation.
1348 config RCU_CPU_STALL_TIMEOUT
1349 int "RCU CPU stall timeout in seconds"
1350 depends on RCU_STALL_COMMON
1354 If a given RCU grace period extends more than the specified
1355 number of seconds, a CPU stall warning is printed. If the
1356 RCU grace period persists, additional CPU stall warnings are
1357 printed at more widely spaced intervals.
1360 bool "Enable tracing for RCU"
1361 depends on DEBUG_KERNEL
1364 This option provides tracing in RCU which presents stats
1365 in debugfs for debugging RCU implementation.
1367 Say Y here if you want to enable RCU tracing
1368 Say N if you are unsure.
1370 config RCU_EQS_DEBUG
1371 bool "Provide debugging asserts for adding NO_HZ support to an arch"
1372 depends on DEBUG_KERNEL
1374 This option provides consistency checks in RCU's handling of
1375 NO_HZ. These checks have proven quite helpful in detecting
1376 bugs in arch-specific NO_HZ code.
1378 Say N here if you need ultimate kernel/user switch latencies
1379 Say Y if you are unsure
1381 endmenu # "RCU Debugging"
1383 config DEBUG_BLOCK_EXT_DEVT
1384 bool "Force extended block device numbers and spread them"
1385 depends on DEBUG_KERNEL
1389 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1390 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1391 YOU ARE DOING. Distros, please enable this and fix whatever
1394 Conventionally, block device numbers are allocated from
1395 predetermined contiguous area. However, extended block area
1396 may introduce non-contiguous block device numbers. This
1397 option forces most block device numbers to be allocated from
1398 the extended space and spreads them to discover kernel or
1399 userland code paths which assume predetermined contiguous
1400 device number allocation.
1402 Note that turning on this debug option shuffles all the
1403 device numbers for all IDE and SCSI devices including libata
1404 ones, so root partition specified using device number
1405 directly (via rdev or root=MAJ:MIN) won't work anymore.
1406 Textual device names (root=/dev/sdXn) will continue to work.
1408 Say N if you are unsure.
1410 config NOTIFIER_ERROR_INJECTION
1411 tristate "Notifier error injection"
1412 depends on DEBUG_KERNEL
1415 This option provides the ability to inject artificial errors to
1416 specified notifier chain callbacks. It is useful to test the error
1417 handling of notifier call chain failures.
1421 config CPU_NOTIFIER_ERROR_INJECT
1422 tristate "CPU notifier error injection module"
1423 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1425 This option provides a kernel module that can be used to test
1426 the error handling of the cpu notifiers by injecting artificial
1427 errors to CPU notifier chain callbacks. It is controlled through
1428 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1430 If the notifier call chain should be failed with some events
1431 notified, write the error code to "actions/<notifier event>/error".
1433 Example: Inject CPU offline error (-1 == -EPERM)
1435 # cd /sys/kernel/debug/notifier-error-inject/cpu
1436 # echo -1 > actions/CPU_DOWN_PREPARE/error
1437 # echo 0 > /sys/devices/system/cpu/cpu1/online
1438 bash: echo: write error: Operation not permitted
1440 To compile this code as a module, choose M here: the module will
1441 be called cpu-notifier-error-inject.
1445 config PM_NOTIFIER_ERROR_INJECT
1446 tristate "PM notifier error injection module"
1447 depends on PM && NOTIFIER_ERROR_INJECTION
1448 default m if PM_DEBUG
1450 This option provides the ability to inject artificial errors to
1451 PM notifier chain callbacks. It is controlled through debugfs
1452 interface /sys/kernel/debug/notifier-error-inject/pm
1454 If the notifier call chain should be failed with some events
1455 notified, write the error code to "actions/<notifier event>/error".
1457 Example: Inject PM suspend error (-12 = -ENOMEM)
1459 # cd /sys/kernel/debug/notifier-error-inject/pm/
1460 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1461 # echo mem > /sys/power/state
1462 bash: echo: write error: Cannot allocate memory
1464 To compile this code as a module, choose M here: the module will
1465 be called pm-notifier-error-inject.
1469 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1470 tristate "OF reconfig notifier error injection module"
1471 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1473 This option provides the ability to inject artificial errors to
1474 OF reconfig notifier chain callbacks. It is controlled
1475 through debugfs interface under
1476 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1478 If the notifier call chain should be failed with some events
1479 notified, write the error code to "actions/<notifier event>/error".
1481 To compile this code as a module, choose M here: the module will
1482 be called of-reconfig-notifier-error-inject.
1486 config FAULT_INJECTION
1487 bool "Fault-injection framework"
1488 depends on DEBUG_KERNEL
1490 Provide fault-injection framework.
1491 For more details, see Documentation/fault-injection/.
1494 bool "Fault-injection capability for kmalloc"
1495 depends on FAULT_INJECTION
1496 depends on SLAB || SLUB
1498 Provide fault-injection capability for kmalloc.
1500 config FAIL_PAGE_ALLOC
1501 bool "Fault-injection capabilitiy for alloc_pages()"
1502 depends on FAULT_INJECTION
1504 Provide fault-injection capability for alloc_pages().
1506 config FAIL_MAKE_REQUEST
1507 bool "Fault-injection capability for disk IO"
1508 depends on FAULT_INJECTION && BLOCK
1510 Provide fault-injection capability for disk IO.
1512 config FAIL_IO_TIMEOUT
1513 bool "Fault-injection capability for faking disk interrupts"
1514 depends on FAULT_INJECTION && BLOCK
1516 Provide fault-injection capability on end IO handling. This
1517 will make the block layer "forget" an interrupt as configured,
1518 thus exercising the error handling.
1520 Only works with drivers that use the generic timeout handling,
1521 for others it wont do anything.
1523 config FAIL_MMC_REQUEST
1524 bool "Fault-injection capability for MMC IO"
1526 depends on FAULT_INJECTION && MMC
1528 Provide fault-injection capability for MMC IO.
1529 This will make the mmc core return data errors. This is
1530 useful to test the error handling in the mmc block device
1531 and to test how the mmc host driver handles retries from
1535 bool "Fault-injection capability for futexes"
1537 depends on FAULT_INJECTION && FUTEX
1539 Provide fault-injection capability for futexes.
1541 config FAULT_INJECTION_DEBUG_FS
1542 bool "Debugfs entries for fault-injection capabilities"
1543 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1545 Enable configuration of fault-injection capabilities via debugfs.
1547 config FAULT_INJECTION_STACKTRACE_FILTER
1548 bool "stacktrace filter for fault-injection capabilities"
1549 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1552 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1554 Provide stacktrace filter for fault-injection capabilities
1557 bool "Latency measuring infrastructure"
1558 depends on HAVE_LATENCYTOP_SUPPORT
1559 depends on DEBUG_KERNEL
1560 depends on STACKTRACE_SUPPORT
1562 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1569 Enable this option if you want to use the LatencyTOP tool
1570 to find out which userspace is blocking on what kernel operations.
1572 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1575 config DEBUG_STRICT_USER_COPY_CHECKS
1576 bool "Strict user copy size checks"
1577 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1578 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1580 Enabling this option turns a certain set of sanity checks for user
1581 copy operations into compile time failures.
1583 The copy_from_user() etc checks are there to help test if there
1584 are sufficient security checks on the length argument of
1585 the copy operation, by having gcc prove that the argument is
1590 source kernel/trace/Kconfig
1592 menu "Runtime Testing"
1595 tristate "Linux Kernel Dump Test Tool Module"
1600 This module enables testing of the different dumping mechanisms by
1601 inducing system failures at predefined crash points.
1602 If you don't need it: say N
1603 Choose M here to compile this code as a module. The module will be
1606 Documentation on how to use the module can be found in
1607 Documentation/fault-injection/provoke-crashes.txt
1609 config TEST_LIST_SORT
1610 bool "Linked list sorting test"
1611 depends on DEBUG_KERNEL
1613 Enable this to turn on 'list_sort()' function test. This test is
1614 executed only once during system boot, so affects only boot time.
1618 config KPROBES_SANITY_TEST
1619 bool "Kprobes sanity tests"
1620 depends on DEBUG_KERNEL
1624 This option provides for testing basic kprobes functionality on
1625 boot. A sample kprobe, jprobe and kretprobe are inserted and
1626 verified for functionality.
1628 Say N if you are unsure.
1630 config BACKTRACE_SELF_TEST
1631 tristate "Self test for the backtrace code"
1632 depends on DEBUG_KERNEL
1635 This option provides a kernel module that can be used to test
1636 the kernel stack backtrace code. This option is not useful
1637 for distributions or general kernels, but only for kernel
1638 developers working on architecture code.
1640 Note that if you want to also test saved backtraces, you will
1641 have to enable STACKTRACE as well.
1643 Say N if you are unsure.
1646 tristate "Red-Black tree test"
1647 depends on DEBUG_KERNEL
1649 A benchmark measuring the performance of the rbtree library.
1650 Also includes rbtree invariant checks.
1652 config INTERVAL_TREE_TEST
1653 tristate "Interval tree test"
1654 depends on m && DEBUG_KERNEL
1655 select INTERVAL_TREE
1657 A benchmark measuring the performance of the interval tree library
1660 tristate "Per cpu operations test"
1661 depends on m && DEBUG_KERNEL
1663 Enable this option to build test module which validates per-cpu
1668 config ATOMIC64_SELFTEST
1669 bool "Perform an atomic64_t self-test at boot"
1671 Enable this option to test the atomic64_t functions at boot.
1675 config ASYNC_RAID6_TEST
1676 tristate "Self test for hardware accelerated raid6 recovery"
1677 depends on ASYNC_RAID6_RECOV
1680 This is a one-shot self test that permutes through the
1681 recovery of all the possible two disk failure scenarios for a
1682 N-disk array. Recovery is performed with the asynchronous
1683 raid6 recovery routines, and will optionally use an offload
1684 engine if one is available.
1689 tristate "Test functions located in the hexdump module at runtime"
1691 config TEST_STRING_HELPERS
1692 tristate "Test functions located in the string_helpers module at runtime"
1695 tristate "Test kstrto*() family of functions at runtime"
1698 tristate "Test printf() family of functions at runtime"
1700 config TEST_RHASHTABLE
1701 tristate "Perform selftest on resizable hash table"
1704 Enable this option to test the rhashtable functions at boot.
1708 endmenu # runtime tests
1710 config PROVIDE_OHCI1394_DMA_INIT
1711 bool "Remote debugging over FireWire early on boot"
1712 depends on PCI && X86
1714 If you want to debug problems which hang or crash the kernel early
1715 on boot and the crashing machine has a FireWire port, you can use
1716 this feature to remotely access the memory of the crashed machine
1717 over FireWire. This employs remote DMA as part of the OHCI1394
1718 specification which is now the standard for FireWire controllers.
1720 With remote DMA, you can monitor the printk buffer remotely using
1721 firescope and access all memory below 4GB using fireproxy from gdb.
1722 Even controlling a kernel debugger is possible using remote DMA.
1726 If ohci1394_dma=early is used as boot parameter, it will initialize
1727 all OHCI1394 controllers which are found in the PCI config space.
1729 As all changes to the FireWire bus such as enabling and disabling
1730 devices cause a bus reset and thereby disable remote DMA for all
1731 devices, be sure to have the cable plugged and FireWire enabled on
1732 the debugging host before booting the debug target for debugging.
1734 This code (~1k) is freed after boot. By then, the firewire stack
1735 in charge of the OHCI-1394 controllers should be used instead.
1737 See Documentation/debugging-via-ohci1394.txt for more information.
1740 bool "Build targets in Documentation/ tree"
1741 depends on HEADERS_CHECK
1743 This option attempts to build objects from the source files in the
1744 kernel Documentation/ tree.
1746 Say N if you are unsure.
1748 config DMA_API_DEBUG
1749 bool "Enable debugging of DMA-API usage"
1750 depends on HAVE_DMA_API_DEBUG
1752 Enable this option to debug the use of the DMA API by device drivers.
1753 With this option you will be able to detect common bugs in device
1754 drivers like double-freeing of DMA mappings or freeing mappings that
1755 were never allocated.
1757 This also attempts to catch cases where a page owned by DMA is
1758 accessed by the cpu in a way that could cause data corruption. For
1759 example, this enables cow_user_page() to check that the source page is
1762 This option causes a performance degradation. Use only if you want to
1763 debug device drivers and dma interactions.
1767 config DMA_API_DEBUG_POISON
1768 bool "Poison coherent DMA buffers"
1769 depends on DMA_API_DEBUG && EXPERT
1771 Poison DMA buffers returned by dma_alloc_coherent unless __GFP_ZERO
1772 is explicitly specified, to catch drivers depending on zeroed buffers
1773 without passing the correct flags.
1775 Only say Y if you're prepared for almost everything to break.
1778 tristate "Test module loading with 'hello world' module"
1782 This builds the "test_module" module that emits "Hello, world"
1783 on printk when loaded. It is designed to be used for basic
1784 evaluation of the module loading subsystem (for example when
1785 validating module verification). It lacks any extra dependencies,
1786 and will not normally be loaded by the system unless explicitly
1791 config TEST_USER_COPY
1792 tristate "Test user/kernel boundary protections"
1796 This builds the "test_user_copy" module that runs sanity checks
1797 on the copy_to/from_user infrastructure, making sure basic
1798 user/kernel boundary testing is working. If it fails to load,
1799 a regression has been detected in the user/kernel memory boundary
1805 tristate "Test BPF filter functionality"
1809 This builds the "test_bpf" module that runs various test vectors
1810 against the BPF interpreter or BPF JIT compiler depending on the
1811 current setting. This is in particular useful for BPF JIT compiler
1812 development, but also to run regression tests against changes in
1813 the interpreter code. It also enables test stubs for eBPF maps and
1814 verifier used by user space verifier testsuite.
1818 config TEST_FIRMWARE
1819 tristate "Test firmware loading via userspace interface"
1821 depends on FW_LOADER
1823 This builds the "test_firmware" module that creates a userspace
1824 interface for testing firmware loading. This can be used to
1825 control the triggering of firmware loading without needing an
1826 actual firmware-using device. The contents can be rechecked by
1832 tristate "udelay test driver"
1835 This builds the "udelay_test" module that helps to make sure
1836 that udelay() is working properly.
1842 depends on HAVE_MEMBLOCK
1844 This option adds a kernel parameter 'memtest', which allows memtest
1846 memtest=0, mean disabled; -- default
1847 memtest=1, mean do 1 test pattern;
1849 memtest=17, mean do 17 test patterns.
1850 If you are unsure how to answer this question, answer N.
1852 config TEST_STATIC_KEYS
1853 tristate "Test static keys"
1857 Test the static key interfaces.
1861 source "samples/Kconfig"
1863 source "lib/Kconfig.kgdb"
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