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.
315 # Select this config option from the architecture Kconfig, if it
316 # is preferred to always offer frame pointers as a config
317 # option on the architecture (regardless of KERNEL_DEBUG):
319 config ARCH_WANT_FRAME_POINTERS
324 bool "Compile the kernel with frame pointers"
325 depends on DEBUG_KERNEL && \
326 (CRIS || M68K || FRV || UML || \
327 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
328 ARCH_WANT_FRAME_POINTERS
329 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
331 If you say Y here the resulting kernel image will be slightly
332 larger and slower, but it gives very useful debugging information
333 in case of kernel bugs. (precise oopses/stacktraces/warnings)
335 config DEBUG_FORCE_WEAK_PER_CPU
336 bool "Force weak per-cpu definitions"
337 depends on DEBUG_KERNEL
339 s390 and alpha require percpu variables in modules to be
340 defined weak to work around addressing range issue which
341 puts the following two restrictions on percpu variable
344 1. percpu symbols must be unique whether static or not
345 2. percpu variables can't be defined inside a function
347 To ensure that generic code follows the above rules, this
348 option forces all percpu variables to be defined as weak.
350 endmenu # "Compiler options"
353 bool "Magic SysRq key"
356 If you say Y here, you will have some control over the system even
357 if the system crashes for example during kernel debugging (e.g., you
358 will be able to flush the buffer cache to disk, reboot the system
359 immediately or dump some status information). This is accomplished
360 by pressing various keys while holding SysRq (Alt+PrintScreen). It
361 also works on a serial console (on PC hardware at least), if you
362 send a BREAK and then within 5 seconds a command keypress. The
363 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
364 unless you really know what this hack does.
366 config MAGIC_SYSRQ_DEFAULT_ENABLE
367 hex "Enable magic SysRq key functions by default"
368 depends on MAGIC_SYSRQ
371 Specifies which SysRq key functions are enabled by default.
372 This may be set to 1 or 0 to enable or disable them all, or
373 to a bitmask as described in Documentation/sysrq.txt.
376 bool "Kernel debugging"
378 Say Y here if you are developing drivers or trying to debug and
379 identify kernel problems.
381 menu "Memory Debugging"
383 source mm/Kconfig.debug
386 bool "Debug object operations"
387 depends on DEBUG_KERNEL
389 If you say Y here, additional code will be inserted into the
390 kernel to track the life time of various objects and validate
391 the operations on those objects.
393 config DEBUG_OBJECTS_SELFTEST
394 bool "Debug objects selftest"
395 depends on DEBUG_OBJECTS
397 This enables the selftest of the object debug code.
399 config DEBUG_OBJECTS_FREE
400 bool "Debug objects in freed memory"
401 depends on DEBUG_OBJECTS
403 This enables checks whether a k/v free operation frees an area
404 which contains an object which has not been deactivated
405 properly. This can make kmalloc/kfree-intensive workloads
408 config DEBUG_OBJECTS_TIMERS
409 bool "Debug timer objects"
410 depends on DEBUG_OBJECTS
412 If you say Y here, additional code will be inserted into the
413 timer routines to track the life time of timer objects and
414 validate the timer operations.
416 config DEBUG_OBJECTS_WORK
417 bool "Debug work objects"
418 depends on DEBUG_OBJECTS
420 If you say Y here, additional code will be inserted into the
421 work queue routines to track the life time of work objects and
422 validate the work operations.
424 config DEBUG_OBJECTS_RCU_HEAD
425 bool "Debug RCU callbacks objects"
426 depends on DEBUG_OBJECTS
428 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
430 config DEBUG_OBJECTS_PERCPU_COUNTER
431 bool "Debug percpu counter objects"
432 depends on DEBUG_OBJECTS
434 If you say Y here, additional code will be inserted into the
435 percpu counter routines to track the life time of percpu counter
436 objects and validate the percpu counter operations.
438 config DEBUG_OBJECTS_ENABLE_DEFAULT
439 int "debug_objects bootup default value (0-1)"
442 depends on DEBUG_OBJECTS
444 Debug objects boot parameter default value
447 bool "Debug slab memory allocations"
448 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
450 Say Y here to have the kernel do limited verification on memory
451 allocation as well as poisoning memory on free to catch use of freed
452 memory. This can make kmalloc/kfree-intensive workloads much slower.
454 config DEBUG_SLAB_LEAK
455 bool "Memory leak debugging"
456 depends on DEBUG_SLAB
459 bool "SLUB debugging on by default"
460 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
463 Boot with debugging on by default. SLUB boots by default with
464 the runtime debug capabilities switched off. Enabling this is
465 equivalent to specifying the "slub_debug" parameter on boot.
466 There is no support for more fine grained debug control like
467 possible with slub_debug=xxx. SLUB debugging may be switched
468 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
473 bool "Enable SLUB performance statistics"
474 depends on SLUB && SYSFS
476 SLUB statistics are useful to debug SLUBs allocation behavior in
477 order find ways to optimize the allocator. This should never be
478 enabled for production use since keeping statistics slows down
479 the allocator by a few percentage points. The slabinfo command
480 supports the determination of the most active slabs to figure
481 out which slabs are relevant to a particular load.
482 Try running: slabinfo -DA
484 config HAVE_DEBUG_KMEMLEAK
487 config DEBUG_KMEMLEAK
488 bool "Kernel memory leak detector"
489 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
491 select STACKTRACE if STACKTRACE_SUPPORT
495 Say Y here if you want to enable the memory leak
496 detector. The memory allocation/freeing is traced in a way
497 similar to the Boehm's conservative garbage collector, the
498 difference being that the orphan objects are not freed but
499 only shown in /sys/kernel/debug/kmemleak. Enabling this
500 feature will introduce an overhead to memory
501 allocations. See Documentation/kmemleak.txt for more
504 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
505 of finding leaks due to the slab objects poisoning.
507 In order to access the kmemleak file, debugfs needs to be
508 mounted (usually at /sys/kernel/debug).
510 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
511 int "Maximum kmemleak early log entries"
512 depends on DEBUG_KMEMLEAK
516 Kmemleak must track all the memory allocations to avoid
517 reporting false positives. Since memory may be allocated or
518 freed before kmemleak is initialised, an early log buffer is
519 used to store these actions. If kmemleak reports "early log
520 buffer exceeded", please increase this value.
522 config DEBUG_KMEMLEAK_TEST
523 tristate "Simple test for the kernel memory leak detector"
524 depends on DEBUG_KMEMLEAK && m
526 This option enables a module that explicitly leaks memory.
530 config DEBUG_KMEMLEAK_DEFAULT_OFF
531 bool "Default kmemleak to off"
532 depends on DEBUG_KMEMLEAK
534 Say Y here to disable kmemleak by default. It can then be enabled
535 on the command line via kmemleak=on.
537 config DEBUG_STACK_USAGE
538 bool "Stack utilization instrumentation"
539 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
541 Enables the display of the minimum amount of free stack which each
542 task has ever had available in the sysrq-T and sysrq-P debug output.
544 This option will slow down process creation somewhat.
548 depends on DEBUG_KERNEL
550 Enable this to turn on extended checks in the virtual-memory system
551 that may impact performance.
555 config DEBUG_VM_VMACACHE
556 bool "Debug VMA caching"
559 Enable this to turn on VMA caching debug information. Doing so
560 can cause significant overhead, so only enable it in non-production
566 bool "Debug VM red-black trees"
569 Enable VM red-black tree debugging information and extra validations.
574 bool "Debug VM translations"
575 depends on DEBUG_KERNEL && X86
577 Enable some costly sanity checks in virtual to page code. This can
578 catch mistakes with virt_to_page() and friends.
582 config DEBUG_NOMMU_REGIONS
583 bool "Debug the global anon/private NOMMU mapping region tree"
584 depends on DEBUG_KERNEL && !MMU
586 This option causes the global tree of anonymous and private mapping
587 regions to be regularly checked for invalid topology.
589 config DEBUG_MEMORY_INIT
590 bool "Debug memory initialisation" if EXPERT
593 Enable this for additional checks during memory initialisation.
594 The sanity checks verify aspects of the VM such as the memory model
595 and other information provided by the architecture. Verbose
596 information will be printed at KERN_DEBUG loglevel depending
597 on the mminit_loglevel= command-line option.
601 config MEMORY_NOTIFIER_ERROR_INJECT
602 tristate "Memory hotplug notifier error injection module"
603 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
605 This option provides the ability to inject artificial errors to
606 memory hotplug notifier chain callbacks. It is controlled through
607 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
609 If the notifier call chain should be failed with some events
610 notified, write the error code to "actions/<notifier event>/error".
612 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
614 # cd /sys/kernel/debug/notifier-error-inject/memory
615 # echo -12 > actions/MEM_GOING_OFFLINE/error
616 # echo offline > /sys/devices/system/memory/memoryXXX/state
617 bash: echo: write error: Cannot allocate memory
619 To compile this code as a module, choose M here: the module will
620 be called memory-notifier-error-inject.
624 config DEBUG_PER_CPU_MAPS
625 bool "Debug access to per_cpu maps"
626 depends on DEBUG_KERNEL
629 Say Y to verify that the per_cpu map being accessed has
630 been set up. This adds a fair amount of code to kernel memory
631 and decreases performance.
636 bool "Highmem debugging"
637 depends on DEBUG_KERNEL && HIGHMEM
639 This option enables additional error checking for high memory
640 systems. Disable for production systems.
642 config HAVE_DEBUG_STACKOVERFLOW
645 config DEBUG_STACKOVERFLOW
646 bool "Check for stack overflows"
647 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
649 Say Y here if you want to check for overflows of kernel, IRQ
650 and exception stacks (if your architecture uses them). This
651 option will show detailed messages if free stack space drops
652 below a certain limit.
654 These kinds of bugs usually occur when call-chains in the
655 kernel get too deep, especially when interrupts are
658 Use this in cases where you see apparently random memory
659 corruption, especially if it appears in 'struct thread_info'
661 If in doubt, say "N".
663 source "lib/Kconfig.kmemcheck"
665 source "lib/Kconfig.kasan"
667 endmenu # "Memory Debugging"
670 bool "Debug shared IRQ handlers"
671 depends on DEBUG_KERNEL
673 Enable this to generate a spurious interrupt as soon as a shared
674 interrupt handler is registered, and just before one is deregistered.
675 Drivers ought to be able to handle interrupts coming in at those
676 points; some don't and need to be caught.
678 menu "Debug Lockups and Hangs"
680 config LOCKUP_DETECTOR
681 bool "Detect Hard and Soft Lockups"
682 depends on DEBUG_KERNEL && !S390
684 Say Y here to enable the kernel to act as a watchdog to detect
685 hard and soft lockups.
687 Softlockups are bugs that cause the kernel to loop in kernel
688 mode for more than 20 seconds, without giving other tasks a
689 chance to run. The current stack trace is displayed upon
690 detection and the system will stay locked up.
692 Hardlockups are bugs that cause the CPU to loop in kernel mode
693 for more than 10 seconds, without letting other interrupts have a
694 chance to run. The current stack trace is displayed upon detection
695 and the system will stay locked up.
697 The overhead should be minimal. A periodic hrtimer runs to
698 generate interrupts and kick the watchdog task every 4 seconds.
699 An NMI is generated every 10 seconds or so to check for hardlockups.
701 The frequency of hrtimer and NMI events and the soft and hard lockup
702 thresholds can be controlled through the sysctl watchdog_thresh.
704 config HARDLOCKUP_DETECTOR
706 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
707 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
709 config BOOTPARAM_HARDLOCKUP_PANIC
710 bool "Panic (Reboot) On Hard Lockups"
711 depends on HARDLOCKUP_DETECTOR
713 Say Y here to enable the kernel to panic on "hard lockups",
714 which are bugs that cause the kernel to loop in kernel
715 mode with interrupts disabled for more than 10 seconds (configurable
716 using the watchdog_thresh sysctl).
720 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
722 depends on HARDLOCKUP_DETECTOR
724 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
725 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
727 config BOOTPARAM_SOFTLOCKUP_PANIC
728 bool "Panic (Reboot) On Soft Lockups"
729 depends on LOCKUP_DETECTOR
731 Say Y here to enable the kernel to panic on "soft lockups",
732 which are bugs that cause the kernel to loop in kernel
733 mode for more than 20 seconds (configurable using the watchdog_thresh
734 sysctl), without giving other tasks a chance to run.
736 The panic can be used in combination with panic_timeout,
737 to cause the system to reboot automatically after a
738 lockup has been detected. This feature is useful for
739 high-availability systems that have uptime guarantees and
740 where a lockup must be resolved ASAP.
744 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
746 depends on LOCKUP_DETECTOR
748 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
749 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
751 config DETECT_HUNG_TASK
752 bool "Detect Hung Tasks"
753 depends on DEBUG_KERNEL
754 default LOCKUP_DETECTOR
756 Say Y here to enable the kernel to detect "hung tasks",
757 which are bugs that cause the task to be stuck in
758 uninterruptible "D" state indefinitiley.
760 When a hung task is detected, the kernel will print the
761 current stack trace (which you should report), but the
762 task will stay in uninterruptible state. If lockdep is
763 enabled then all held locks will also be reported. This
764 feature has negligible overhead.
766 config DEFAULT_HUNG_TASK_TIMEOUT
767 int "Default timeout for hung task detection (in seconds)"
768 depends on DETECT_HUNG_TASK
771 This option controls the default timeout (in seconds) used
772 to determine when a task has become non-responsive and should
775 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
776 sysctl or by writing a value to
777 /proc/sys/kernel/hung_task_timeout_secs.
779 A timeout of 0 disables the check. The default is two minutes.
780 Keeping the default should be fine in most cases.
782 config BOOTPARAM_HUNG_TASK_PANIC
783 bool "Panic (Reboot) On Hung Tasks"
784 depends on DETECT_HUNG_TASK
786 Say Y here to enable the kernel to panic on "hung tasks",
787 which are bugs that cause the kernel to leave a task stuck
788 in uninterruptible "D" state.
790 The panic can be used in combination with panic_timeout,
791 to cause the system to reboot automatically after a
792 hung task has been detected. This feature is useful for
793 high-availability systems that have uptime guarantees and
794 where a hung tasks must be resolved ASAP.
798 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
800 depends on DETECT_HUNG_TASK
802 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
803 default 1 if BOOTPARAM_HUNG_TASK_PANIC
805 endmenu # "Debug lockups and hangs"
810 Say Y here to enable the kernel to panic when it oopses. This
811 has the same effect as setting oops=panic on the kernel command
814 This feature is useful to ensure that the kernel does not do
815 anything erroneous after an oops which could result in data
816 corruption or other issues.
820 config PANIC_ON_OOPS_VALUE
823 default 0 if !PANIC_ON_OOPS
824 default 1 if PANIC_ON_OOPS
830 Set the timeout value (in seconds) until a reboot occurs when the
831 the kernel panics. If n = 0, then we wait forever. A timeout
832 value n > 0 will wait n seconds before rebooting, while a timeout
833 value n < 0 will reboot immediately.
836 bool "Collect scheduler debugging info"
837 depends on DEBUG_KERNEL && PROC_FS
840 If you say Y here, the /proc/sched_debug file will be provided
841 that can help debug the scheduler. The runtime overhead of this
849 bool "Collect scheduler statistics"
850 depends on DEBUG_KERNEL && PROC_FS
853 If you say Y here, additional code will be inserted into the
854 scheduler and related routines to collect statistics about
855 scheduler behavior and provide them in /proc/schedstat. These
856 stats may be useful for both tuning and debugging the scheduler
857 If you aren't debugging the scheduler or trying to tune a specific
858 application, you can say N to avoid the very slight overhead
861 config SCHED_STACK_END_CHECK
862 bool "Detect stack corruption on calls to schedule()"
863 depends on DEBUG_KERNEL
866 This option checks for a stack overrun on calls to schedule().
867 If the stack end location is found to be over written always panic as
868 the content of the corrupted region can no longer be trusted.
869 This is to ensure no erroneous behaviour occurs which could result in
870 data corruption or a sporadic crash at a later stage once the region
871 is examined. The runtime overhead introduced is minimal.
873 config DEBUG_TIMEKEEPING
874 bool "Enable extra timekeeping sanity checking"
876 This option will enable additional timekeeping sanity checks
877 which may be helpful when diagnosing issues where timekeeping
878 problems are suspected.
880 This may include checks in the timekeeping hotpaths, so this
881 option may have a (very small) performance impact to some
887 bool "Collect kernel timers statistics"
888 depends on DEBUG_KERNEL && PROC_FS
890 If you say Y here, additional code will be inserted into the
891 timer routines to collect statistics about kernel timers being
892 reprogrammed. The statistics can be read from /proc/timer_stats.
893 The statistics collection is started by writing 1 to /proc/timer_stats,
894 writing 0 stops it. This feature is useful to collect information
895 about timer usage patterns in kernel and userspace. This feature
896 is lightweight if enabled in the kernel config but not activated
897 (it defaults to deactivated on bootup and will only be activated
898 if some application like powertop activates it explicitly).
901 bool "Debug preemptible kernel"
902 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
905 If you say Y here then the kernel will use a debug variant of the
906 commonly used smp_processor_id() function and will print warnings
907 if kernel code uses it in a preemption-unsafe way. Also, the kernel
908 will detect preemption count underflows.
910 menu "Lock Debugging (spinlocks, mutexes, etc...)"
912 config DEBUG_RT_MUTEXES
913 bool "RT Mutex debugging, deadlock detection"
914 depends on DEBUG_KERNEL && RT_MUTEXES
916 This allows rt mutex semantics violations and rt mutex related
917 deadlocks (lockups) to be detected and reported automatically.
919 config RT_MUTEX_TESTER
920 bool "Built-in scriptable tester for rt-mutexes"
921 depends on DEBUG_KERNEL && RT_MUTEXES && BROKEN
923 This option enables a rt-mutex tester.
925 config DEBUG_SPINLOCK
926 bool "Spinlock and rw-lock debugging: basic checks"
927 depends on DEBUG_KERNEL
928 select UNINLINE_SPIN_UNLOCK
930 Say Y here and build SMP to catch missing spinlock initialization
931 and certain other kinds of spinlock errors commonly made. This is
932 best used in conjunction with the NMI watchdog so that spinlock
933 deadlocks are also debuggable.
936 bool "Mutex debugging: basic checks"
937 depends on DEBUG_KERNEL
939 This feature allows mutex semantics violations to be detected and
942 config DEBUG_WW_MUTEX_SLOWPATH
943 bool "Wait/wound mutex debugging: Slowpath testing"
944 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
945 select DEBUG_LOCK_ALLOC
946 select DEBUG_SPINLOCK
949 This feature enables slowpath testing for w/w mutex users by
950 injecting additional -EDEADLK wound/backoff cases. Together with
951 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
952 will test all possible w/w mutex interface abuse with the
953 exception of simply not acquiring all the required locks.
954 Note that this feature can introduce significant overhead, so
955 it really should not be enabled in a production or distro kernel,
956 even a debug kernel. If you are a driver writer, enable it. If
957 you are a distro, do not.
959 config DEBUG_LOCK_ALLOC
960 bool "Lock debugging: detect incorrect freeing of live locks"
961 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
962 select DEBUG_SPINLOCK
966 This feature will check whether any held lock (spinlock, rwlock,
967 mutex or rwsem) is incorrectly freed by the kernel, via any of the
968 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
969 vfree(), etc.), whether a live lock is incorrectly reinitialized via
970 spin_lock_init()/mutex_init()/etc., or whether there is any lock
971 held during task exit.
974 bool "Lock debugging: prove locking correctness"
975 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
977 select DEBUG_SPINLOCK
979 select DEBUG_LOCK_ALLOC
980 select TRACE_IRQFLAGS
983 This feature enables the kernel to prove that all locking
984 that occurs in the kernel runtime is mathematically
985 correct: that under no circumstance could an arbitrary (and
986 not yet triggered) combination of observed locking
987 sequences (on an arbitrary number of CPUs, running an
988 arbitrary number of tasks and interrupt contexts) cause a
991 In short, this feature enables the kernel to report locking
992 related deadlocks before they actually occur.
994 The proof does not depend on how hard and complex a
995 deadlock scenario would be to trigger: how many
996 participant CPUs, tasks and irq-contexts would be needed
997 for it to trigger. The proof also does not depend on
998 timing: if a race and a resulting deadlock is possible
999 theoretically (no matter how unlikely the race scenario
1000 is), it will be proven so and will immediately be
1001 reported by the kernel (once the event is observed that
1002 makes the deadlock theoretically possible).
1004 If a deadlock is impossible (i.e. the locking rules, as
1005 observed by the kernel, are mathematically correct), the
1006 kernel reports nothing.
1008 NOTE: this feature can also be enabled for rwlocks, mutexes
1009 and rwsems - in which case all dependencies between these
1010 different locking variants are observed and mapped too, and
1011 the proof of observed correctness is also maintained for an
1012 arbitrary combination of these separate locking variants.
1014 For more details, see Documentation/locking/lockdep-design.txt.
1018 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1020 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
1025 bool "Lock usage statistics"
1026 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1028 select DEBUG_SPINLOCK
1029 select DEBUG_MUTEXES
1030 select DEBUG_LOCK_ALLOC
1033 This feature enables tracking lock contention points
1035 For more details, see Documentation/locking/lockstat.txt
1037 This also enables lock events required by "perf lock",
1039 If you want to use "perf lock", you also need to turn on
1040 CONFIG_EVENT_TRACING.
1042 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1043 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1045 config DEBUG_LOCKDEP
1046 bool "Lock dependency engine debugging"
1047 depends on DEBUG_KERNEL && LOCKDEP
1049 If you say Y here, the lock dependency engine will do
1050 additional runtime checks to debug itself, at the price
1051 of more runtime overhead.
1053 config DEBUG_ATOMIC_SLEEP
1054 bool "Sleep inside atomic section checking"
1055 select PREEMPT_COUNT
1056 depends on DEBUG_KERNEL
1058 If you say Y here, various routines which may sleep will become very
1059 noisy if they are called inside atomic sections: when a spinlock is
1060 held, inside an rcu read side critical section, inside preempt disabled
1061 sections, inside an interrupt, etc...
1063 config DEBUG_LOCKING_API_SELFTESTS
1064 bool "Locking API boot-time self-tests"
1065 depends on DEBUG_KERNEL
1067 Say Y here if you want the kernel to run a short self-test during
1068 bootup. The self-test checks whether common types of locking bugs
1069 are detected by debugging mechanisms or not. (if you disable
1070 lock debugging then those bugs wont be detected of course.)
1071 The following locking APIs are covered: spinlocks, rwlocks,
1074 config LOCK_TORTURE_TEST
1075 tristate "torture tests for locking"
1076 depends on DEBUG_KERNEL
1080 This option provides a kernel module that runs torture tests
1081 on kernel locking primitives. The kernel module may be built
1082 after the fact on the running kernel to be tested, if desired.
1084 Say Y here if you want kernel locking-primitive torture tests
1085 to be built into the kernel.
1086 Say M if you want these torture tests to build as a module.
1087 Say N if you are unsure.
1089 endmenu # lock debugging
1091 config TRACE_IRQFLAGS
1094 Enables hooks to interrupt enabling and disabling for
1095 either tracing or lock debugging.
1098 bool "Stack backtrace support"
1099 depends on STACKTRACE_SUPPORT
1101 This option causes the kernel to create a /proc/pid/stack for
1102 every process, showing its current stack trace.
1103 It is also used by various kernel debugging features that require
1104 stack trace generation.
1106 config DEBUG_KOBJECT
1107 bool "kobject debugging"
1108 depends on DEBUG_KERNEL
1110 If you say Y here, some extra kobject debugging messages will be sent
1113 config DEBUG_KOBJECT_RELEASE
1114 bool "kobject release debugging"
1115 depends on DEBUG_OBJECTS_TIMERS
1117 kobjects are reference counted objects. This means that their
1118 last reference count put is not predictable, and the kobject can
1119 live on past the point at which a driver decides to drop it's
1120 initial reference to the kobject gained on allocation. An
1121 example of this would be a struct device which has just been
1124 However, some buggy drivers assume that after such an operation,
1125 the memory backing the kobject can be immediately freed. This
1126 goes completely against the principles of a refcounted object.
1128 If you say Y here, the kernel will delay the release of kobjects
1129 on the last reference count to improve the visibility of this
1130 kind of kobject release bug.
1132 config HAVE_DEBUG_BUGVERBOSE
1135 config DEBUG_BUGVERBOSE
1136 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1137 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1140 Say Y here to make BUG() panics output the file name and line number
1141 of the BUG call as well as the EIP and oops trace. This aids
1142 debugging but costs about 70-100K of memory.
1145 bool "Debug linked list manipulation"
1146 depends on DEBUG_KERNEL
1148 Enable this to turn on extended checks in the linked-list
1153 config DEBUG_PI_LIST
1154 bool "Debug priority linked list manipulation"
1155 depends on DEBUG_KERNEL
1157 Enable this to turn on extended checks in the priority-ordered
1158 linked-list (plist) walking routines. This checks the entire
1159 list multiple times during each manipulation.
1164 bool "Debug SG table operations"
1165 depends on DEBUG_KERNEL
1167 Enable this to turn on checks on scatter-gather tables. This can
1168 help find problems with drivers that do not properly initialize
1173 config DEBUG_NOTIFIERS
1174 bool "Debug notifier call chains"
1175 depends on DEBUG_KERNEL
1177 Enable this to turn on sanity checking for notifier call chains.
1178 This is most useful for kernel developers to make sure that
1179 modules properly unregister themselves from notifier chains.
1180 This is a relatively cheap check but if you care about maximum
1183 config DEBUG_CREDENTIALS
1184 bool "Debug credential management"
1185 depends on DEBUG_KERNEL
1187 Enable this to turn on some debug checking for credential
1188 management. The additional code keeps track of the number of
1189 pointers from task_structs to any given cred struct, and checks to
1190 see that this number never exceeds the usage count of the cred
1193 Furthermore, if SELinux is enabled, this also checks that the
1194 security pointer in the cred struct is never seen to be invalid.
1198 menu "RCU Debugging"
1201 def_bool PROVE_LOCKING
1203 config PROVE_RCU_REPEATEDLY
1204 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1205 depends on PROVE_RCU
1208 By itself, PROVE_RCU will disable checking upon issuing the
1209 first warning (or "splat"). This feature prevents such
1210 disabling, allowing multiple RCU-lockdep warnings to be printed
1213 Say Y to allow multiple RCU-lockdep warnings per boot.
1215 Say N if you are unsure.
1217 config SPARSE_RCU_POINTER
1218 bool "RCU debugging: sparse-based checks for pointer usage"
1221 This feature enables the __rcu sparse annotation for
1222 RCU-protected pointers. This annotation will cause sparse
1223 to flag any non-RCU used of annotated pointers. This can be
1224 helpful when debugging RCU usage. Please note that this feature
1225 is not intended to enforce code cleanliness; it is instead merely
1228 Say Y to make sparse flag questionable use of RCU-protected pointers
1230 Say N if you are unsure.
1236 config RCU_TORTURE_TEST
1237 tristate "torture tests for RCU"
1238 depends on DEBUG_KERNEL
1244 This option provides a kernel module that runs torture tests
1245 on the RCU infrastructure. The kernel module may be built
1246 after the fact on the running kernel to be tested, if desired.
1248 Say Y here if you want RCU torture tests to be built into
1250 Say M if you want the RCU torture tests to build as a module.
1251 Say N if you are unsure.
1253 config RCU_TORTURE_TEST_RUNNABLE
1254 bool "torture tests for RCU runnable by default"
1255 depends on RCU_TORTURE_TEST = y
1258 This option provides a way to build the RCU torture tests
1259 directly into the kernel without them starting up at boot
1260 time. You can use /proc/sys/kernel/rcutorture_runnable
1261 to manually override this setting. This /proc file is
1262 available only when the RCU torture tests have been built
1265 Say Y here if you want the RCU torture tests to start during
1266 boot (you probably don't).
1267 Say N here if you want the RCU torture tests to start only
1268 after being manually enabled via /proc.
1270 config RCU_TORTURE_TEST_SLOW_PREINIT
1271 bool "Slow down RCU grace-period pre-initialization to expose races"
1272 depends on RCU_TORTURE_TEST
1274 This option delays grace-period pre-initialization (the
1275 propagation of CPU-hotplug changes up the rcu_node combining
1276 tree) for a few jiffies between initializing each pair of
1277 consecutive rcu_node structures. This helps to expose races
1278 involving grace-period pre-initialization, in other words, it
1279 makes your kernel less stable. It can also greatly increase
1280 grace-period latency, especially on systems with large numbers
1281 of CPUs. This is useful when torture-testing RCU, but in
1282 almost no other circumstance.
1284 Say Y here if you want your system to crash and hang more often.
1285 Say N if you want a sane system.
1287 config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1288 int "How much to slow down RCU grace-period pre-initialization"
1291 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1293 This option specifies the number of jiffies to wait between
1294 each rcu_node structure pre-initialization step.
1296 config RCU_TORTURE_TEST_SLOW_INIT
1297 bool "Slow down RCU grace-period initialization to expose races"
1298 depends on RCU_TORTURE_TEST
1300 This option delays grace-period initialization for a few
1301 jiffies between initializing each pair of consecutive
1302 rcu_node structures. This helps to expose races involving
1303 grace-period initialization, in other words, it makes your
1304 kernel less stable. It can also greatly increase grace-period
1305 latency, especially on systems with large numbers of CPUs.
1306 This is useful when torture-testing RCU, but in almost no
1309 Say Y here if you want your system to crash and hang more often.
1310 Say N if you want a sane system.
1312 config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1313 int "How much to slow down RCU grace-period initialization"
1316 depends on RCU_TORTURE_TEST_SLOW_INIT
1318 This option specifies the number of jiffies to wait between
1319 each rcu_node structure initialization.
1321 config RCU_TORTURE_TEST_SLOW_CLEANUP
1322 bool "Slow down RCU grace-period cleanup to expose races"
1323 depends on RCU_TORTURE_TEST
1325 This option delays grace-period cleanup for a few jiffies
1326 between cleaning up each pair of consecutive rcu_node
1327 structures. This helps to expose races involving grace-period
1328 cleanup, in other words, it makes your kernel less stable.
1329 It can also greatly increase grace-period latency, especially
1330 on systems with large numbers of CPUs. This is useful when
1331 torture-testing RCU, but in almost no other circumstance.
1333 Say Y here if you want your system to crash and hang more often.
1334 Say N if you want a sane system.
1336 config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1337 int "How much to slow down RCU grace-period cleanup"
1340 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1342 This option specifies the number of jiffies to wait between
1343 each rcu_node structure cleanup operation.
1345 config RCU_CPU_STALL_TIMEOUT
1346 int "RCU CPU stall timeout in seconds"
1347 depends on RCU_STALL_COMMON
1351 If a given RCU grace period extends more than the specified
1352 number of seconds, a CPU stall warning is printed. If the
1353 RCU grace period persists, additional CPU stall warnings are
1354 printed at more widely spaced intervals.
1356 config RCU_CPU_STALL_INFO
1357 bool "Print additional diagnostics on RCU CPU stall"
1358 depends on (TREE_RCU || PREEMPT_RCU) && DEBUG_KERNEL
1361 For each stalled CPU that is aware of the current RCU grace
1362 period, print out additional per-CPU diagnostic information
1363 regarding scheduling-clock ticks, idle state, and,
1364 for RCU_FAST_NO_HZ kernels, idle-entry state.
1366 Say N if you are unsure.
1368 Say Y if you want to enable such diagnostics.
1371 bool "Enable tracing for RCU"
1372 depends on DEBUG_KERNEL
1375 This option provides tracing in RCU which presents stats
1376 in debugfs for debugging RCU implementation.
1378 Say Y here if you want to enable RCU tracing
1379 Say N if you are unsure.
1381 config RCU_EQS_DEBUG
1382 bool "Use this when adding any sort of NO_HZ support to your arch"
1383 depends on DEBUG_KERNEL
1385 This option provides consistency checks in RCU's handling of
1386 NO_HZ. These checks have proven quite helpful in detecting
1387 bugs in arch-specific NO_HZ code.
1389 Say N here if you need ultimate kernel/user switch latencies
1390 Say Y if you are unsure
1392 endmenu # "RCU Debugging"
1394 config DEBUG_BLOCK_EXT_DEVT
1395 bool "Force extended block device numbers and spread them"
1396 depends on DEBUG_KERNEL
1400 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1401 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1402 YOU ARE DOING. Distros, please enable this and fix whatever
1405 Conventionally, block device numbers are allocated from
1406 predetermined contiguous area. However, extended block area
1407 may introduce non-contiguous block device numbers. This
1408 option forces most block device numbers to be allocated from
1409 the extended space and spreads them to discover kernel or
1410 userland code paths which assume predetermined contiguous
1411 device number allocation.
1413 Note that turning on this debug option shuffles all the
1414 device numbers for all IDE and SCSI devices including libata
1415 ones, so root partition specified using device number
1416 directly (via rdev or root=MAJ:MIN) won't work anymore.
1417 Textual device names (root=/dev/sdXn) will continue to work.
1419 Say N if you are unsure.
1421 config NOTIFIER_ERROR_INJECTION
1422 tristate "Notifier error injection"
1423 depends on DEBUG_KERNEL
1426 This option provides the ability to inject artificial errors to
1427 specified notifier chain callbacks. It is useful to test the error
1428 handling of notifier call chain failures.
1432 config CPU_NOTIFIER_ERROR_INJECT
1433 tristate "CPU notifier error injection module"
1434 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1436 This option provides a kernel module that can be used to test
1437 the error handling of the cpu notifiers by injecting artificial
1438 errors to CPU notifier chain callbacks. It is controlled through
1439 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1441 If the notifier call chain should be failed with some events
1442 notified, write the error code to "actions/<notifier event>/error".
1444 Example: Inject CPU offline error (-1 == -EPERM)
1446 # cd /sys/kernel/debug/notifier-error-inject/cpu
1447 # echo -1 > actions/CPU_DOWN_PREPARE/error
1448 # echo 0 > /sys/devices/system/cpu/cpu1/online
1449 bash: echo: write error: Operation not permitted
1451 To compile this code as a module, choose M here: the module will
1452 be called cpu-notifier-error-inject.
1456 config PM_NOTIFIER_ERROR_INJECT
1457 tristate "PM notifier error injection module"
1458 depends on PM && NOTIFIER_ERROR_INJECTION
1459 default m if PM_DEBUG
1461 This option provides the ability to inject artificial errors to
1462 PM notifier chain callbacks. It is controlled through debugfs
1463 interface /sys/kernel/debug/notifier-error-inject/pm
1465 If the notifier call chain should be failed with some events
1466 notified, write the error code to "actions/<notifier event>/error".
1468 Example: Inject PM suspend error (-12 = -ENOMEM)
1470 # cd /sys/kernel/debug/notifier-error-inject/pm/
1471 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1472 # echo mem > /sys/power/state
1473 bash: echo: write error: Cannot allocate memory
1475 To compile this code as a module, choose M here: the module will
1476 be called pm-notifier-error-inject.
1480 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1481 tristate "OF reconfig notifier error injection module"
1482 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1484 This option provides the ability to inject artificial errors to
1485 OF reconfig notifier chain callbacks. It is controlled
1486 through debugfs interface under
1487 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1489 If the notifier call chain should be failed with some events
1490 notified, write the error code to "actions/<notifier event>/error".
1492 To compile this code as a module, choose M here: the module will
1493 be called of-reconfig-notifier-error-inject.
1497 config FAULT_INJECTION
1498 bool "Fault-injection framework"
1499 depends on DEBUG_KERNEL
1501 Provide fault-injection framework.
1502 For more details, see Documentation/fault-injection/.
1505 bool "Fault-injection capability for kmalloc"
1506 depends on FAULT_INJECTION
1507 depends on SLAB || SLUB
1509 Provide fault-injection capability for kmalloc.
1511 config FAIL_PAGE_ALLOC
1512 bool "Fault-injection capabilitiy for alloc_pages()"
1513 depends on FAULT_INJECTION
1515 Provide fault-injection capability for alloc_pages().
1517 config FAIL_MAKE_REQUEST
1518 bool "Fault-injection capability for disk IO"
1519 depends on FAULT_INJECTION && BLOCK
1521 Provide fault-injection capability for disk IO.
1523 config FAIL_IO_TIMEOUT
1524 bool "Fault-injection capability for faking disk interrupts"
1525 depends on FAULT_INJECTION && BLOCK
1527 Provide fault-injection capability on end IO handling. This
1528 will make the block layer "forget" an interrupt as configured,
1529 thus exercising the error handling.
1531 Only works with drivers that use the generic timeout handling,
1532 for others it wont do anything.
1534 config FAIL_MMC_REQUEST
1535 bool "Fault-injection capability for MMC IO"
1537 depends on FAULT_INJECTION && MMC
1539 Provide fault-injection capability for MMC IO.
1540 This will make the mmc core return data errors. This is
1541 useful to test the error handling in the mmc block device
1542 and to test how the mmc host driver handles retries from
1545 config FAULT_INJECTION_DEBUG_FS
1546 bool "Debugfs entries for fault-injection capabilities"
1547 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1549 Enable configuration of fault-injection capabilities via debugfs.
1551 config FAULT_INJECTION_STACKTRACE_FILTER
1552 bool "stacktrace filter for fault-injection capabilities"
1553 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1556 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1558 Provide stacktrace filter for fault-injection capabilities
1561 bool "Latency measuring infrastructure"
1562 depends on HAVE_LATENCYTOP_SUPPORT
1563 depends on DEBUG_KERNEL
1564 depends on STACKTRACE_SUPPORT
1566 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1573 Enable this option if you want to use the LatencyTOP tool
1574 to find out which userspace is blocking on what kernel operations.
1576 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1579 config DEBUG_STRICT_USER_COPY_CHECKS
1580 bool "Strict user copy size checks"
1581 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1582 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1584 Enabling this option turns a certain set of sanity checks for user
1585 copy operations into compile time failures.
1587 The copy_from_user() etc checks are there to help test if there
1588 are sufficient security checks on the length argument of
1589 the copy operation, by having gcc prove that the argument is
1594 source kernel/trace/Kconfig
1596 menu "Runtime Testing"
1599 tristate "Linux Kernel Dump Test Tool Module"
1604 This module enables testing of the different dumping mechanisms by
1605 inducing system failures at predefined crash points.
1606 If you don't need it: say N
1607 Choose M here to compile this code as a module. The module will be
1610 Documentation on how to use the module can be found in
1611 Documentation/fault-injection/provoke-crashes.txt
1613 config TEST_LIST_SORT
1614 bool "Linked list sorting test"
1615 depends on DEBUG_KERNEL
1617 Enable this to turn on 'list_sort()' function test. This test is
1618 executed only once during system boot, so affects only boot time.
1622 config KPROBES_SANITY_TEST
1623 bool "Kprobes sanity tests"
1624 depends on DEBUG_KERNEL
1628 This option provides for testing basic kprobes functionality on
1629 boot. A sample kprobe, jprobe and kretprobe are inserted and
1630 verified for functionality.
1632 Say N if you are unsure.
1634 config BACKTRACE_SELF_TEST
1635 tristate "Self test for the backtrace code"
1636 depends on DEBUG_KERNEL
1639 This option provides a kernel module that can be used to test
1640 the kernel stack backtrace code. This option is not useful
1641 for distributions or general kernels, but only for kernel
1642 developers working on architecture code.
1644 Note that if you want to also test saved backtraces, you will
1645 have to enable STACKTRACE as well.
1647 Say N if you are unsure.
1650 tristate "Red-Black tree test"
1651 depends on DEBUG_KERNEL
1653 A benchmark measuring the performance of the rbtree library.
1654 Also includes rbtree invariant checks.
1656 config INTERVAL_TREE_TEST
1657 tristate "Interval tree test"
1658 depends on m && DEBUG_KERNEL
1659 select INTERVAL_TREE
1661 A benchmark measuring the performance of the interval tree library
1664 tristate "Per cpu operations test"
1665 depends on m && DEBUG_KERNEL
1667 Enable this option to build test module which validates per-cpu
1672 config ATOMIC64_SELFTEST
1673 bool "Perform an atomic64_t self-test at boot"
1675 Enable this option to test the atomic64_t functions at boot.
1679 config ASYNC_RAID6_TEST
1680 tristate "Self test for hardware accelerated raid6 recovery"
1681 depends on ASYNC_RAID6_RECOV
1684 This is a one-shot self test that permutes through the
1685 recovery of all the possible two disk failure scenarios for a
1686 N-disk array. Recovery is performed with the asynchronous
1687 raid6 recovery routines, and will optionally use an offload
1688 engine if one is available.
1693 tristate "Test functions located in the hexdump module at runtime"
1695 config TEST_STRING_HELPERS
1696 tristate "Test functions located in the string_helpers module at runtime"
1699 tristate "Test kstrto*() family of functions at runtime"
1701 config TEST_RHASHTABLE
1702 tristate "Perform selftest on resizable hash table"
1705 Enable this option to test the rhashtable functions at boot.
1709 endmenu # runtime tests
1711 config PROVIDE_OHCI1394_DMA_INIT
1712 bool "Remote debugging over FireWire early on boot"
1713 depends on PCI && X86
1715 If you want to debug problems which hang or crash the kernel early
1716 on boot and the crashing machine has a FireWire port, you can use
1717 this feature to remotely access the memory of the crashed machine
1718 over FireWire. This employs remote DMA as part of the OHCI1394
1719 specification which is now the standard for FireWire controllers.
1721 With remote DMA, you can monitor the printk buffer remotely using
1722 firescope and access all memory below 4GB using fireproxy from gdb.
1723 Even controlling a kernel debugger is possible using remote DMA.
1727 If ohci1394_dma=early is used as boot parameter, it will initialize
1728 all OHCI1394 controllers which are found in the PCI config space.
1730 As all changes to the FireWire bus such as enabling and disabling
1731 devices cause a bus reset and thereby disable remote DMA for all
1732 devices, be sure to have the cable plugged and FireWire enabled on
1733 the debugging host before booting the debug target for debugging.
1735 This code (~1k) is freed after boot. By then, the firewire stack
1736 in charge of the OHCI-1394 controllers should be used instead.
1738 See Documentation/debugging-via-ohci1394.txt for more information.
1741 bool "Build targets in Documentation/ tree"
1742 depends on HEADERS_CHECK
1744 This option attempts to build objects from the source files in the
1745 kernel Documentation/ tree.
1747 Say N if you are unsure.
1749 config DMA_API_DEBUG
1750 bool "Enable debugging of DMA-API usage"
1751 depends on HAVE_DMA_API_DEBUG
1753 Enable this option to debug the use of the DMA API by device drivers.
1754 With this option you will be able to detect common bugs in device
1755 drivers like double-freeing of DMA mappings or freeing mappings that
1756 were never allocated.
1758 This also attempts to catch cases where a page owned by DMA is
1759 accessed by the cpu in a way that could cause data corruption. For
1760 example, this enables cow_user_page() to check that the source page is
1763 This option causes a performance degradation. Use only if you want to
1764 debug device drivers and dma interactions.
1769 tristate "Test module loading with 'hello world' module"
1773 This builds the "test_module" module that emits "Hello, world"
1774 on printk when loaded. It is designed to be used for basic
1775 evaluation of the module loading subsystem (for example when
1776 validating module verification). It lacks any extra dependencies,
1777 and will not normally be loaded by the system unless explicitly
1782 config TEST_USER_COPY
1783 tristate "Test user/kernel boundary protections"
1787 This builds the "test_user_copy" module that runs sanity checks
1788 on the copy_to/from_user infrastructure, making sure basic
1789 user/kernel boundary testing is working. If it fails to load,
1790 a regression has been detected in the user/kernel memory boundary
1796 tristate "Test BPF filter functionality"
1800 This builds the "test_bpf" module that runs various test vectors
1801 against the BPF interpreter or BPF JIT compiler depending on the
1802 current setting. This is in particular useful for BPF JIT compiler
1803 development, but also to run regression tests against changes in
1804 the interpreter code. It also enables test stubs for eBPF maps and
1805 verifier used by user space verifier testsuite.
1809 config TEST_FIRMWARE
1810 tristate "Test firmware loading via userspace interface"
1812 depends on FW_LOADER
1814 This builds the "test_firmware" module that creates a userspace
1815 interface for testing firmware loading. This can be used to
1816 control the triggering of firmware loading without needing an
1817 actual firmware-using device. The contents can be rechecked by
1823 tristate "udelay test driver"
1826 This builds the "udelay_test" module that helps to make sure
1827 that udelay() is working properly.
1833 depends on HAVE_MEMBLOCK
1835 This option adds a kernel parameter 'memtest', which allows memtest
1837 memtest=0, mean disabled; -- default
1838 memtest=1, mean do 1 test pattern;
1840 memtest=17, mean do 17 test patterns.
1841 If you are unsure how to answer this question, answer N.
1843 source "samples/Kconfig"
1845 source "lib/Kconfig.kgdb"
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