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)"
200 default 1024 if !64BIT
201 default 2048 if 64BIT
203 Tell gcc to warn at build time for stack frames larger than this.
204 Setting this too low will cause a lot of warnings.
205 Setting it to 0 disables the warning.
208 config STRIP_ASM_SYMS
209 bool "Strip assembler-generated symbols during link"
212 Strip internal assembler-generated symbols during a link (symbols
213 that look like '.Lxxx') so they don't pollute the output of
214 get_wchan() and suchlike.
217 bool "Generate readable assembler code"
218 depends on DEBUG_KERNEL
220 Disable some compiler optimizations that tend to generate human unreadable
221 assembler output. This may make the kernel slightly slower, but it helps
222 to keep kernel developers who have to stare a lot at assembler listings
225 config UNUSED_SYMBOLS
226 bool "Enable unused/obsolete exported symbols"
229 Unused but exported symbols make the kernel needlessly bigger. For
230 that reason most of these unused exports will soon be removed. This
231 option is provided temporarily to provide a transition period in case
232 some external kernel module needs one of these symbols anyway. If you
233 encounter such a case in your module, consider if you are actually
234 using the right API. (rationale: since nobody in the kernel is using
235 this in a module, there is a pretty good chance it's actually the
236 wrong interface to use). If you really need the symbol, please send a
237 mail to the linux kernel mailing list mentioning the symbol and why
238 you really need it, and what the merge plan to the mainline kernel for
242 bool "Track page owner"
243 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
246 select PAGE_EXTENSION
248 This keeps track of what call chain is the owner of a page, may
249 help to find bare alloc_page(s) leaks. Even if you include this
250 feature on your build, it is disabled in default. You should pass
251 "page_owner=on" to boot parameter in order to enable it. Eats
252 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
253 for user-space helper.
258 bool "Debug Filesystem"
260 debugfs is a virtual file system that kernel developers use to put
261 debugging files into. Enable this option to be able to read and
262 write to these files.
264 For detailed documentation on the debugfs API, see
265 Documentation/DocBook/filesystems.
270 bool "Run 'make headers_check' when building vmlinux"
273 This option will extract the user-visible kernel headers whenever
274 building the kernel, and will run basic sanity checks on them to
275 ensure that exported files do not attempt to include files which
276 were not exported, etc.
278 If you're making modifications to header files which are
279 relevant for userspace, say 'Y', and check the headers
280 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
281 your build tree), to make sure they're suitable.
283 config DEBUG_SECTION_MISMATCH
284 bool "Enable full Section mismatch analysis"
286 The section mismatch analysis checks if there are illegal
287 references from one section to another section.
288 During linktime or runtime, some sections are dropped;
289 any use of code/data previously in these sections would
290 most likely result in an oops.
291 In the code, functions and variables are annotated with
292 __init,, etc. (see the full list in include/linux/init.h),
293 which results in the code/data being placed in specific sections.
294 The section mismatch analysis is always performed after a full
295 kernel build, and enabling this option causes the following
296 additional steps to occur:
297 - Add the option -fno-inline-functions-called-once to gcc commands.
298 When inlining a function annotated with __init in a non-init
299 function, we would lose the section information and thus
300 the analysis would not catch the illegal reference.
301 This option tells gcc to inline less (but it does result in
303 - Run the section mismatch analysis for each module/built-in.o file.
304 When we run the section mismatch analysis on vmlinux.o, we
305 lose valueble information about where the mismatch was
307 Running the analysis for each module/built-in.o file
308 tells where the mismatch happens much closer to the
309 source. The drawback is that the same mismatch is
310 reported at least twice.
311 - Enable verbose reporting from modpost in order to help resolve
312 the section mismatches that are reported.
314 config SECTION_MISMATCH_WARN_ONLY
315 bool "Make section mismatch errors non-fatal"
318 If you say N here, the build process will fail if there are any
319 section mismatch, instead of just throwing warnings.
324 # Select this config option from the architecture Kconfig, if it
325 # is preferred to always offer frame pointers as a config
326 # option on the architecture (regardless of KERNEL_DEBUG):
328 config ARCH_WANT_FRAME_POINTERS
333 bool "Compile the kernel with frame pointers"
334 depends on DEBUG_KERNEL && \
335 (CRIS || M68K || FRV || UML || \
336 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
337 ARCH_WANT_FRAME_POINTERS
338 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
340 If you say Y here the resulting kernel image will be slightly
341 larger and slower, but it gives very useful debugging information
342 in case of kernel bugs. (precise oopses/stacktraces/warnings)
344 config DEBUG_FORCE_WEAK_PER_CPU
345 bool "Force weak per-cpu definitions"
346 depends on DEBUG_KERNEL
348 s390 and alpha require percpu variables in modules to be
349 defined weak to work around addressing range issue which
350 puts the following two restrictions on percpu variable
353 1. percpu symbols must be unique whether static or not
354 2. percpu variables can't be defined inside a function
356 To ensure that generic code follows the above rules, this
357 option forces all percpu variables to be defined as weak.
359 endmenu # "Compiler options"
362 bool "Magic SysRq key"
365 If you say Y here, you will have some control over the system even
366 if the system crashes for example during kernel debugging (e.g., you
367 will be able to flush the buffer cache to disk, reboot the system
368 immediately or dump some status information). This is accomplished
369 by pressing various keys while holding SysRq (Alt+PrintScreen). It
370 also works on a serial console (on PC hardware at least), if you
371 send a BREAK and then within 5 seconds a command keypress. The
372 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
373 unless you really know what this hack does.
375 config MAGIC_SYSRQ_DEFAULT_ENABLE
376 hex "Enable magic SysRq key functions by default"
377 depends on MAGIC_SYSRQ
380 Specifies which SysRq key functions are enabled by default.
381 This may be set to 1 or 0 to enable or disable them all, or
382 to a bitmask as described in Documentation/sysrq.txt.
385 bool "Kernel debugging"
387 Say Y here if you are developing drivers or trying to debug and
388 identify kernel problems.
390 menu "Memory Debugging"
392 source mm/Kconfig.debug
395 bool "Debug object operations"
396 depends on DEBUG_KERNEL
398 If you say Y here, additional code will be inserted into the
399 kernel to track the life time of various objects and validate
400 the operations on those objects.
402 config DEBUG_OBJECTS_SELFTEST
403 bool "Debug objects selftest"
404 depends on DEBUG_OBJECTS
406 This enables the selftest of the object debug code.
408 config DEBUG_OBJECTS_FREE
409 bool "Debug objects in freed memory"
410 depends on DEBUG_OBJECTS
412 This enables checks whether a k/v free operation frees an area
413 which contains an object which has not been deactivated
414 properly. This can make kmalloc/kfree-intensive workloads
417 config DEBUG_OBJECTS_TIMERS
418 bool "Debug timer objects"
419 depends on DEBUG_OBJECTS
421 If you say Y here, additional code will be inserted into the
422 timer routines to track the life time of timer objects and
423 validate the timer operations.
425 config DEBUG_OBJECTS_WORK
426 bool "Debug work objects"
427 depends on DEBUG_OBJECTS
429 If you say Y here, additional code will be inserted into the
430 work queue routines to track the life time of work objects and
431 validate the work operations.
433 config DEBUG_OBJECTS_RCU_HEAD
434 bool "Debug RCU callbacks objects"
435 depends on DEBUG_OBJECTS
437 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
439 config DEBUG_OBJECTS_PERCPU_COUNTER
440 bool "Debug percpu counter objects"
441 depends on DEBUG_OBJECTS
443 If you say Y here, additional code will be inserted into the
444 percpu counter routines to track the life time of percpu counter
445 objects and validate the percpu counter operations.
447 config DEBUG_OBJECTS_ENABLE_DEFAULT
448 int "debug_objects bootup default value (0-1)"
451 depends on DEBUG_OBJECTS
453 Debug objects boot parameter default value
456 bool "Debug slab memory allocations"
457 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
459 Say Y here to have the kernel do limited verification on memory
460 allocation as well as poisoning memory on free to catch use of freed
461 memory. This can make kmalloc/kfree-intensive workloads much slower.
463 config DEBUG_SLAB_LEAK
464 bool "Memory leak debugging"
465 depends on DEBUG_SLAB
468 bool "SLUB debugging on by default"
469 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
472 Boot with debugging on by default. SLUB boots by default with
473 the runtime debug capabilities switched off. Enabling this is
474 equivalent to specifying the "slub_debug" parameter on boot.
475 There is no support for more fine grained debug control like
476 possible with slub_debug=xxx. SLUB debugging may be switched
477 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
482 bool "Enable SLUB performance statistics"
483 depends on SLUB && SYSFS
485 SLUB statistics are useful to debug SLUBs allocation behavior in
486 order find ways to optimize the allocator. This should never be
487 enabled for production use since keeping statistics slows down
488 the allocator by a few percentage points. The slabinfo command
489 supports the determination of the most active slabs to figure
490 out which slabs are relevant to a particular load.
491 Try running: slabinfo -DA
493 config HAVE_DEBUG_KMEMLEAK
496 config DEBUG_KMEMLEAK
497 bool "Kernel memory leak detector"
498 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
500 select STACKTRACE if STACKTRACE_SUPPORT
504 Say Y here if you want to enable the memory leak
505 detector. The memory allocation/freeing is traced in a way
506 similar to the Boehm's conservative garbage collector, the
507 difference being that the orphan objects are not freed but
508 only shown in /sys/kernel/debug/kmemleak. Enabling this
509 feature will introduce an overhead to memory
510 allocations. See Documentation/kmemleak.txt for more
513 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
514 of finding leaks due to the slab objects poisoning.
516 In order to access the kmemleak file, debugfs needs to be
517 mounted (usually at /sys/kernel/debug).
519 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
520 int "Maximum kmemleak early log entries"
521 depends on DEBUG_KMEMLEAK
525 Kmemleak must track all the memory allocations to avoid
526 reporting false positives. Since memory may be allocated or
527 freed before kmemleak is initialised, an early log buffer is
528 used to store these actions. If kmemleak reports "early log
529 buffer exceeded", please increase this value.
531 config DEBUG_KMEMLEAK_TEST
532 tristate "Simple test for the kernel memory leak detector"
533 depends on DEBUG_KMEMLEAK && m
535 This option enables a module that explicitly leaks memory.
539 config DEBUG_KMEMLEAK_DEFAULT_OFF
540 bool "Default kmemleak to off"
541 depends on DEBUG_KMEMLEAK
543 Say Y here to disable kmemleak by default. It can then be enabled
544 on the command line via kmemleak=on.
546 config DEBUG_STACK_USAGE
547 bool "Stack utilization instrumentation"
548 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
550 Enables the display of the minimum amount of free stack which each
551 task has ever had available in the sysrq-T and sysrq-P debug output.
553 This option will slow down process creation somewhat.
557 depends on DEBUG_KERNEL
559 Enable this to turn on extended checks in the virtual-memory system
560 that may impact performance.
564 config DEBUG_VM_VMACACHE
565 bool "Debug VMA caching"
568 Enable this to turn on VMA caching debug information. Doing so
569 can cause significant overhead, so only enable it in non-production
575 bool "Debug VM red-black trees"
578 Enable VM red-black tree debugging information and extra validations.
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 RT_MUTEX_TESTER
929 bool "Built-in scriptable tester for rt-mutexes"
930 depends on DEBUG_KERNEL && RT_MUTEXES && BROKEN
932 This option enables a rt-mutex tester.
934 config DEBUG_SPINLOCK
935 bool "Spinlock and rw-lock debugging: basic checks"
936 depends on DEBUG_KERNEL
937 select UNINLINE_SPIN_UNLOCK
939 Say Y here and build SMP to catch missing spinlock initialization
940 and certain other kinds of spinlock errors commonly made. This is
941 best used in conjunction with the NMI watchdog so that spinlock
942 deadlocks are also debuggable.
945 bool "Mutex debugging: basic checks"
946 depends on DEBUG_KERNEL
948 This feature allows mutex semantics violations to be detected and
951 config DEBUG_WW_MUTEX_SLOWPATH
952 bool "Wait/wound mutex debugging: Slowpath testing"
953 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
954 select DEBUG_LOCK_ALLOC
955 select DEBUG_SPINLOCK
958 This feature enables slowpath testing for w/w mutex users by
959 injecting additional -EDEADLK wound/backoff cases. Together with
960 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
961 will test all possible w/w mutex interface abuse with the
962 exception of simply not acquiring all the required locks.
963 Note that this feature can introduce significant overhead, so
964 it really should not be enabled in a production or distro kernel,
965 even a debug kernel. If you are a driver writer, enable it. If
966 you are a distro, do not.
968 config DEBUG_LOCK_ALLOC
969 bool "Lock debugging: detect incorrect freeing of live locks"
970 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
971 select DEBUG_SPINLOCK
975 This feature will check whether any held lock (spinlock, rwlock,
976 mutex or rwsem) is incorrectly freed by the kernel, via any of the
977 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
978 vfree(), etc.), whether a live lock is incorrectly reinitialized via
979 spin_lock_init()/mutex_init()/etc., or whether there is any lock
980 held during task exit.
983 bool "Lock debugging: prove locking correctness"
984 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
986 select DEBUG_SPINLOCK
988 select DEBUG_LOCK_ALLOC
989 select TRACE_IRQFLAGS
992 This feature enables the kernel to prove that all locking
993 that occurs in the kernel runtime is mathematically
994 correct: that under no circumstance could an arbitrary (and
995 not yet triggered) combination of observed locking
996 sequences (on an arbitrary number of CPUs, running an
997 arbitrary number of tasks and interrupt contexts) cause a
1000 In short, this feature enables the kernel to report locking
1001 related deadlocks before they actually occur.
1003 The proof does not depend on how hard and complex a
1004 deadlock scenario would be to trigger: how many
1005 participant CPUs, tasks and irq-contexts would be needed
1006 for it to trigger. The proof also does not depend on
1007 timing: if a race and a resulting deadlock is possible
1008 theoretically (no matter how unlikely the race scenario
1009 is), it will be proven so and will immediately be
1010 reported by the kernel (once the event is observed that
1011 makes the deadlock theoretically possible).
1013 If a deadlock is impossible (i.e. the locking rules, as
1014 observed by the kernel, are mathematically correct), the
1015 kernel reports nothing.
1017 NOTE: this feature can also be enabled for rwlocks, mutexes
1018 and rwsems - in which case all dependencies between these
1019 different locking variants are observed and mapped too, and
1020 the proof of observed correctness is also maintained for an
1021 arbitrary combination of these separate locking variants.
1023 For more details, see Documentation/locking/lockdep-design.txt.
1027 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1029 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
1034 bool "Lock usage statistics"
1035 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1037 select DEBUG_SPINLOCK
1038 select DEBUG_MUTEXES
1039 select DEBUG_LOCK_ALLOC
1042 This feature enables tracking lock contention points
1044 For more details, see Documentation/locking/lockstat.txt
1046 This also enables lock events required by "perf lock",
1048 If you want to use "perf lock", you also need to turn on
1049 CONFIG_EVENT_TRACING.
1051 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1052 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1054 config DEBUG_LOCKDEP
1055 bool "Lock dependency engine debugging"
1056 depends on DEBUG_KERNEL && LOCKDEP
1058 If you say Y here, the lock dependency engine will do
1059 additional runtime checks to debug itself, at the price
1060 of more runtime overhead.
1062 config DEBUG_ATOMIC_SLEEP
1063 bool "Sleep inside atomic section checking"
1064 select PREEMPT_COUNT
1065 depends on DEBUG_KERNEL
1067 If you say Y here, various routines which may sleep will become very
1068 noisy if they are called inside atomic sections: when a spinlock is
1069 held, inside an rcu read side critical section, inside preempt disabled
1070 sections, inside an interrupt, etc...
1072 config DEBUG_LOCKING_API_SELFTESTS
1073 bool "Locking API boot-time self-tests"
1074 depends on DEBUG_KERNEL
1076 Say Y here if you want the kernel to run a short self-test during
1077 bootup. The self-test checks whether common types of locking bugs
1078 are detected by debugging mechanisms or not. (if you disable
1079 lock debugging then those bugs wont be detected of course.)
1080 The following locking APIs are covered: spinlocks, rwlocks,
1083 config LOCK_TORTURE_TEST
1084 tristate "torture tests for locking"
1085 depends on DEBUG_KERNEL
1089 This option provides a kernel module that runs torture tests
1090 on kernel locking primitives. The kernel module may be built
1091 after the fact on the running kernel to be tested, if desired.
1093 Say Y here if you want kernel locking-primitive torture tests
1094 to be built into the kernel.
1095 Say M if you want these torture tests to build as a module.
1096 Say N if you are unsure.
1098 endmenu # lock debugging
1100 config TRACE_IRQFLAGS
1103 Enables hooks to interrupt enabling and disabling for
1104 either tracing or lock debugging.
1107 bool "Stack backtrace support"
1108 depends on STACKTRACE_SUPPORT
1110 This option causes the kernel to create a /proc/pid/stack for
1111 every process, showing its current stack trace.
1112 It is also used by various kernel debugging features that require
1113 stack trace generation.
1115 config DEBUG_KOBJECT
1116 bool "kobject debugging"
1117 depends on DEBUG_KERNEL
1119 If you say Y here, some extra kobject debugging messages will be sent
1122 config DEBUG_KOBJECT_RELEASE
1123 bool "kobject release debugging"
1124 depends on DEBUG_OBJECTS_TIMERS
1126 kobjects are reference counted objects. This means that their
1127 last reference count put is not predictable, and the kobject can
1128 live on past the point at which a driver decides to drop it's
1129 initial reference to the kobject gained on allocation. An
1130 example of this would be a struct device which has just been
1133 However, some buggy drivers assume that after such an operation,
1134 the memory backing the kobject can be immediately freed. This
1135 goes completely against the principles of a refcounted object.
1137 If you say Y here, the kernel will delay the release of kobjects
1138 on the last reference count to improve the visibility of this
1139 kind of kobject release bug.
1141 config HAVE_DEBUG_BUGVERBOSE
1144 config DEBUG_BUGVERBOSE
1145 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1146 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1149 Say Y here to make BUG() panics output the file name and line number
1150 of the BUG call as well as the EIP and oops trace. This aids
1151 debugging but costs about 70-100K of memory.
1154 bool "Debug linked list manipulation"
1155 depends on DEBUG_KERNEL
1157 Enable this to turn on extended checks in the linked-list
1162 config DEBUG_PI_LIST
1163 bool "Debug priority linked list manipulation"
1164 depends on DEBUG_KERNEL
1166 Enable this to turn on extended checks in the priority-ordered
1167 linked-list (plist) walking routines. This checks the entire
1168 list multiple times during each manipulation.
1173 bool "Debug SG table operations"
1174 depends on DEBUG_KERNEL
1176 Enable this to turn on checks on scatter-gather tables. This can
1177 help find problems with drivers that do not properly initialize
1182 config DEBUG_NOTIFIERS
1183 bool "Debug notifier call chains"
1184 depends on DEBUG_KERNEL
1186 Enable this to turn on sanity checking for notifier call chains.
1187 This is most useful for kernel developers to make sure that
1188 modules properly unregister themselves from notifier chains.
1189 This is a relatively cheap check but if you care about maximum
1192 config DEBUG_CREDENTIALS
1193 bool "Debug credential management"
1194 depends on DEBUG_KERNEL
1196 Enable this to turn on some debug checking for credential
1197 management. The additional code keeps track of the number of
1198 pointers from task_structs to any given cred struct, and checks to
1199 see that this number never exceeds the usage count of the cred
1202 Furthermore, if SELinux is enabled, this also checks that the
1203 security pointer in the cred struct is never seen to be invalid.
1207 menu "RCU Debugging"
1210 def_bool PROVE_LOCKING
1212 config PROVE_RCU_REPEATEDLY
1213 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1214 depends on PROVE_RCU
1217 By itself, PROVE_RCU will disable checking upon issuing the
1218 first warning (or "splat"). This feature prevents such
1219 disabling, allowing multiple RCU-lockdep warnings to be printed
1222 Say Y to allow multiple RCU-lockdep warnings per boot.
1224 Say N if you are unsure.
1226 config SPARSE_RCU_POINTER
1227 bool "RCU debugging: sparse-based checks for pointer usage"
1230 This feature enables the __rcu sparse annotation for
1231 RCU-protected pointers. This annotation will cause sparse
1232 to flag any non-RCU used of annotated pointers. This can be
1233 helpful when debugging RCU usage. Please note that this feature
1234 is not intended to enforce code cleanliness; it is instead merely
1237 Say Y to make sparse flag questionable use of RCU-protected pointers
1239 Say N if you are unsure.
1245 config RCU_TORTURE_TEST
1246 tristate "torture tests for RCU"
1247 depends on DEBUG_KERNEL
1253 This option provides a kernel module that runs torture tests
1254 on the RCU infrastructure. The kernel module may be built
1255 after the fact on the running kernel to be tested, if desired.
1257 Say Y here if you want RCU torture tests to be built into
1259 Say M if you want the RCU torture tests to build as a module.
1260 Say N if you are unsure.
1262 config RCU_TORTURE_TEST_RUNNABLE
1263 bool "torture tests for RCU runnable by default"
1264 depends on RCU_TORTURE_TEST = y
1267 This option provides a way to build the RCU torture tests
1268 directly into the kernel without them starting up at boot
1269 time. You can use /proc/sys/kernel/rcutorture_runnable
1270 to manually override this setting. This /proc file is
1271 available only when the RCU torture tests have been built
1274 Say Y here if you want the RCU torture tests to start during
1275 boot (you probably don't).
1276 Say N here if you want the RCU torture tests to start only
1277 after being manually enabled via /proc.
1279 config RCU_TORTURE_TEST_SLOW_PREINIT
1280 bool "Slow down RCU grace-period pre-initialization to expose races"
1281 depends on RCU_TORTURE_TEST
1283 This option delays grace-period pre-initialization (the
1284 propagation of CPU-hotplug changes up the rcu_node combining
1285 tree) for a few jiffies between initializing each pair of
1286 consecutive rcu_node structures. This helps to expose races
1287 involving grace-period pre-initialization, in other words, it
1288 makes your kernel less stable. It can also greatly increase
1289 grace-period latency, especially on systems with large numbers
1290 of CPUs. This is useful when torture-testing RCU, but in
1291 almost no other circumstance.
1293 Say Y here if you want your system to crash and hang more often.
1294 Say N if you want a sane system.
1296 config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1297 int "How much to slow down RCU grace-period pre-initialization"
1300 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1302 This option specifies the number of jiffies to wait between
1303 each rcu_node structure pre-initialization step.
1305 config RCU_TORTURE_TEST_SLOW_INIT
1306 bool "Slow down RCU grace-period initialization to expose races"
1307 depends on RCU_TORTURE_TEST
1309 This option delays grace-period initialization for a few
1310 jiffies between initializing each pair of consecutive
1311 rcu_node structures. This helps to expose races involving
1312 grace-period initialization, in other words, it makes your
1313 kernel less stable. It can also greatly increase grace-period
1314 latency, especially on systems with large numbers of CPUs.
1315 This is useful when torture-testing RCU, but in almost no
1318 Say Y here if you want your system to crash and hang more often.
1319 Say N if you want a sane system.
1321 config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1322 int "How much to slow down RCU grace-period initialization"
1325 depends on RCU_TORTURE_TEST_SLOW_INIT
1327 This option specifies the number of jiffies to wait between
1328 each rcu_node structure initialization.
1330 config RCU_TORTURE_TEST_SLOW_CLEANUP
1331 bool "Slow down RCU grace-period cleanup to expose races"
1332 depends on RCU_TORTURE_TEST
1334 This option delays grace-period cleanup for a few jiffies
1335 between cleaning up each pair of consecutive rcu_node
1336 structures. This helps to expose races involving grace-period
1337 cleanup, in other words, it makes your kernel less stable.
1338 It can also greatly increase grace-period latency, especially
1339 on systems with large numbers of CPUs. This is useful when
1340 torture-testing RCU, but in almost no other circumstance.
1342 Say Y here if you want your system to crash and hang more often.
1343 Say N if you want a sane system.
1345 config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1346 int "How much to slow down RCU grace-period cleanup"
1349 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1351 This option specifies the number of jiffies to wait between
1352 each rcu_node structure cleanup operation.
1354 config RCU_CPU_STALL_TIMEOUT
1355 int "RCU CPU stall timeout in seconds"
1356 depends on RCU_STALL_COMMON
1360 If a given RCU grace period extends more than the specified
1361 number of seconds, a CPU stall warning is printed. If the
1362 RCU grace period persists, additional CPU stall warnings are
1363 printed at more widely spaced intervals.
1365 config RCU_CPU_STALL_INFO
1366 bool "Print additional diagnostics on RCU CPU stall"
1367 depends on (TREE_RCU || PREEMPT_RCU) && DEBUG_KERNEL
1370 For each stalled CPU that is aware of the current RCU grace
1371 period, print out additional per-CPU diagnostic information
1372 regarding scheduling-clock ticks, idle state, and,
1373 for RCU_FAST_NO_HZ kernels, idle-entry state.
1375 Say N if you are unsure.
1377 Say Y if you want to enable such diagnostics.
1380 bool "Enable tracing for RCU"
1381 depends on DEBUG_KERNEL
1384 This option provides tracing in RCU which presents stats
1385 in debugfs for debugging RCU implementation.
1387 Say Y here if you want to enable RCU tracing
1388 Say N if you are unsure.
1390 config RCU_EQS_DEBUG
1391 bool "Use this when adding any sort of NO_HZ support to your arch"
1392 depends on DEBUG_KERNEL
1394 This option provides consistency checks in RCU's handling of
1395 NO_HZ. These checks have proven quite helpful in detecting
1396 bugs in arch-specific NO_HZ code.
1398 Say N here if you need ultimate kernel/user switch latencies
1399 Say Y if you are unsure
1401 endmenu # "RCU Debugging"
1403 config DEBUG_BLOCK_EXT_DEVT
1404 bool "Force extended block device numbers and spread them"
1405 depends on DEBUG_KERNEL
1409 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1410 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1411 YOU ARE DOING. Distros, please enable this and fix whatever
1414 Conventionally, block device numbers are allocated from
1415 predetermined contiguous area. However, extended block area
1416 may introduce non-contiguous block device numbers. This
1417 option forces most block device numbers to be allocated from
1418 the extended space and spreads them to discover kernel or
1419 userland code paths which assume predetermined contiguous
1420 device number allocation.
1422 Note that turning on this debug option shuffles all the
1423 device numbers for all IDE and SCSI devices including libata
1424 ones, so root partition specified using device number
1425 directly (via rdev or root=MAJ:MIN) won't work anymore.
1426 Textual device names (root=/dev/sdXn) will continue to work.
1428 Say N if you are unsure.
1430 config NOTIFIER_ERROR_INJECTION
1431 tristate "Notifier error injection"
1432 depends on DEBUG_KERNEL
1435 This option provides the ability to inject artificial errors to
1436 specified notifier chain callbacks. It is useful to test the error
1437 handling of notifier call chain failures.
1441 config CPU_NOTIFIER_ERROR_INJECT
1442 tristate "CPU notifier error injection module"
1443 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1445 This option provides a kernel module that can be used to test
1446 the error handling of the cpu notifiers by injecting artificial
1447 errors to CPU notifier chain callbacks. It is controlled through
1448 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1450 If the notifier call chain should be failed with some events
1451 notified, write the error code to "actions/<notifier event>/error".
1453 Example: Inject CPU offline error (-1 == -EPERM)
1455 # cd /sys/kernel/debug/notifier-error-inject/cpu
1456 # echo -1 > actions/CPU_DOWN_PREPARE/error
1457 # echo 0 > /sys/devices/system/cpu/cpu1/online
1458 bash: echo: write error: Operation not permitted
1460 To compile this code as a module, choose M here: the module will
1461 be called cpu-notifier-error-inject.
1465 config PM_NOTIFIER_ERROR_INJECT
1466 tristate "PM notifier error injection module"
1467 depends on PM && NOTIFIER_ERROR_INJECTION
1468 default m if PM_DEBUG
1470 This option provides the ability to inject artificial errors to
1471 PM notifier chain callbacks. It is controlled through debugfs
1472 interface /sys/kernel/debug/notifier-error-inject/pm
1474 If the notifier call chain should be failed with some events
1475 notified, write the error code to "actions/<notifier event>/error".
1477 Example: Inject PM suspend error (-12 = -ENOMEM)
1479 # cd /sys/kernel/debug/notifier-error-inject/pm/
1480 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1481 # echo mem > /sys/power/state
1482 bash: echo: write error: Cannot allocate memory
1484 To compile this code as a module, choose M here: the module will
1485 be called pm-notifier-error-inject.
1489 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1490 tristate "OF reconfig notifier error injection module"
1491 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1493 This option provides the ability to inject artificial errors to
1494 OF reconfig notifier chain callbacks. It is controlled
1495 through debugfs interface under
1496 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1498 If the notifier call chain should be failed with some events
1499 notified, write the error code to "actions/<notifier event>/error".
1501 To compile this code as a module, choose M here: the module will
1502 be called of-reconfig-notifier-error-inject.
1506 config FAULT_INJECTION
1507 bool "Fault-injection framework"
1508 depends on DEBUG_KERNEL
1510 Provide fault-injection framework.
1511 For more details, see Documentation/fault-injection/.
1514 bool "Fault-injection capability for kmalloc"
1515 depends on FAULT_INJECTION
1516 depends on SLAB || SLUB
1518 Provide fault-injection capability for kmalloc.
1520 config FAIL_PAGE_ALLOC
1521 bool "Fault-injection capabilitiy for alloc_pages()"
1522 depends on FAULT_INJECTION
1524 Provide fault-injection capability for alloc_pages().
1526 config FAIL_MAKE_REQUEST
1527 bool "Fault-injection capability for disk IO"
1528 depends on FAULT_INJECTION && BLOCK
1530 Provide fault-injection capability for disk IO.
1532 config FAIL_IO_TIMEOUT
1533 bool "Fault-injection capability for faking disk interrupts"
1534 depends on FAULT_INJECTION && BLOCK
1536 Provide fault-injection capability on end IO handling. This
1537 will make the block layer "forget" an interrupt as configured,
1538 thus exercising the error handling.
1540 Only works with drivers that use the generic timeout handling,
1541 for others it wont do anything.
1543 config FAIL_MMC_REQUEST
1544 bool "Fault-injection capability for MMC IO"
1546 depends on FAULT_INJECTION && MMC
1548 Provide fault-injection capability for MMC IO.
1549 This will make the mmc core return data errors. This is
1550 useful to test the error handling in the mmc block device
1551 and to test how the mmc host driver handles retries from
1554 config FAULT_INJECTION_DEBUG_FS
1555 bool "Debugfs entries for fault-injection capabilities"
1556 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1558 Enable configuration of fault-injection capabilities via debugfs.
1560 config FAULT_INJECTION_STACKTRACE_FILTER
1561 bool "stacktrace filter for fault-injection capabilities"
1562 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1565 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1567 Provide stacktrace filter for fault-injection capabilities
1570 bool "Latency measuring infrastructure"
1571 depends on HAVE_LATENCYTOP_SUPPORT
1572 depends on DEBUG_KERNEL
1573 depends on STACKTRACE_SUPPORT
1575 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1582 Enable this option if you want to use the LatencyTOP tool
1583 to find out which userspace is blocking on what kernel operations.
1585 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1588 config DEBUG_STRICT_USER_COPY_CHECKS
1589 bool "Strict user copy size checks"
1590 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1591 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1593 Enabling this option turns a certain set of sanity checks for user
1594 copy operations into compile time failures.
1596 The copy_from_user() etc checks are there to help test if there
1597 are sufficient security checks on the length argument of
1598 the copy operation, by having gcc prove that the argument is
1603 source kernel/trace/Kconfig
1605 menu "Runtime Testing"
1608 tristate "Linux Kernel Dump Test Tool Module"
1613 This module enables testing of the different dumping mechanisms by
1614 inducing system failures at predefined crash points.
1615 If you don't need it: say N
1616 Choose M here to compile this code as a module. The module will be
1619 Documentation on how to use the module can be found in
1620 Documentation/fault-injection/provoke-crashes.txt
1622 config TEST_LIST_SORT
1623 bool "Linked list sorting test"
1624 depends on DEBUG_KERNEL
1626 Enable this to turn on 'list_sort()' function test. This test is
1627 executed only once during system boot, so affects only boot time.
1631 config KPROBES_SANITY_TEST
1632 bool "Kprobes sanity tests"
1633 depends on DEBUG_KERNEL
1637 This option provides for testing basic kprobes functionality on
1638 boot. A sample kprobe, jprobe and kretprobe are inserted and
1639 verified for functionality.
1641 Say N if you are unsure.
1643 config BACKTRACE_SELF_TEST
1644 tristate "Self test for the backtrace code"
1645 depends on DEBUG_KERNEL
1648 This option provides a kernel module that can be used to test
1649 the kernel stack backtrace code. This option is not useful
1650 for distributions or general kernels, but only for kernel
1651 developers working on architecture code.
1653 Note that if you want to also test saved backtraces, you will
1654 have to enable STACKTRACE as well.
1656 Say N if you are unsure.
1659 tristate "Red-Black tree test"
1660 depends on DEBUG_KERNEL
1662 A benchmark measuring the performance of the rbtree library.
1663 Also includes rbtree invariant checks.
1665 config INTERVAL_TREE_TEST
1666 tristate "Interval tree test"
1667 depends on m && DEBUG_KERNEL
1668 select INTERVAL_TREE
1670 A benchmark measuring the performance of the interval tree library
1673 tristate "Per cpu operations test"
1674 depends on m && DEBUG_KERNEL
1676 Enable this option to build test module which validates per-cpu
1681 config ATOMIC64_SELFTEST
1682 bool "Perform an atomic64_t self-test at boot"
1684 Enable this option to test the atomic64_t functions at boot.
1688 config ASYNC_RAID6_TEST
1689 tristate "Self test for hardware accelerated raid6 recovery"
1690 depends on ASYNC_RAID6_RECOV
1693 This is a one-shot self test that permutes through the
1694 recovery of all the possible two disk failure scenarios for a
1695 N-disk array. Recovery is performed with the asynchronous
1696 raid6 recovery routines, and will optionally use an offload
1697 engine if one is available.
1702 tristate "Test functions located in the hexdump module at runtime"
1704 config TEST_STRING_HELPERS
1705 tristate "Test functions located in the string_helpers module at runtime"
1708 tristate "Test kstrto*() family of functions at runtime"
1710 config TEST_RHASHTABLE
1711 tristate "Perform selftest on resizable hash table"
1714 Enable this option to test the rhashtable functions at boot.
1718 endmenu # runtime tests
1720 config PROVIDE_OHCI1394_DMA_INIT
1721 bool "Remote debugging over FireWire early on boot"
1722 depends on PCI && X86
1724 If you want to debug problems which hang or crash the kernel early
1725 on boot and the crashing machine has a FireWire port, you can use
1726 this feature to remotely access the memory of the crashed machine
1727 over FireWire. This employs remote DMA as part of the OHCI1394
1728 specification which is now the standard for FireWire controllers.
1730 With remote DMA, you can monitor the printk buffer remotely using
1731 firescope and access all memory below 4GB using fireproxy from gdb.
1732 Even controlling a kernel debugger is possible using remote DMA.
1736 If ohci1394_dma=early is used as boot parameter, it will initialize
1737 all OHCI1394 controllers which are found in the PCI config space.
1739 As all changes to the FireWire bus such as enabling and disabling
1740 devices cause a bus reset and thereby disable remote DMA for all
1741 devices, be sure to have the cable plugged and FireWire enabled on
1742 the debugging host before booting the debug target for debugging.
1744 This code (~1k) is freed after boot. By then, the firewire stack
1745 in charge of the OHCI-1394 controllers should be used instead.
1747 See Documentation/debugging-via-ohci1394.txt for more information.
1750 bool "Build targets in Documentation/ tree"
1751 depends on HEADERS_CHECK
1753 This option attempts to build objects from the source files in the
1754 kernel Documentation/ tree.
1756 Say N if you are unsure.
1758 config DMA_API_DEBUG
1759 bool "Enable debugging of DMA-API usage"
1760 depends on HAVE_DMA_API_DEBUG
1762 Enable this option to debug the use of the DMA API by device drivers.
1763 With this option you will be able to detect common bugs in device
1764 drivers like double-freeing of DMA mappings or freeing mappings that
1765 were never allocated.
1767 This also attempts to catch cases where a page owned by DMA is
1768 accessed by the cpu in a way that could cause data corruption. For
1769 example, this enables cow_user_page() to check that the source page is
1772 This option causes a performance degradation. Use only if you want to
1773 debug device drivers and dma interactions.
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 source "samples/Kconfig"
1854 source "lib/Kconfig.kgdb"
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