1 menu "printk and dmesg options"
4 bool "Show timing information on printks"
7 Selecting this option causes time stamps of the printk()
8 messages to be added to the output of the syslog() system
9 call and at the console.
11 The timestamp is always recorded internally, and exported
12 to /dev/kmsg. This flag just specifies if the timestamp should
13 be included, not that the timestamp is recorded.
15 The behavior is also controlled by the kernel command line
16 parameter printk.time=1. See Documentation/kernel-parameters.txt
18 config MESSAGE_LOGLEVEL_DEFAULT
19 int "Default message log level (1-7)"
23 Default log level for printk statements with no specified priority.
25 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
26 that are auditing their logs closely may want to set it to a lower
29 config BOOT_PRINTK_DELAY
30 bool "Delay each boot printk message by N milliseconds"
31 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
33 This build option allows you to read kernel boot messages
34 by inserting a short delay after each one. The delay is
35 specified in milliseconds on the kernel command line,
38 It is likely that you would also need to use "lpj=M" to preset
39 the "loops per jiffie" value.
40 See a previous boot log for the "lpj" value to use for your
41 system, and then set "lpj=M" before setting "boot_delay=N".
42 NOTE: Using this option may adversely affect SMP systems.
43 I.e., processors other than the first one may not boot up.
44 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
45 what it believes to be lockup conditions.
48 bool "Enable dynamic printk() support"
54 Compiles debug level messages into the kernel, which would not
55 otherwise be available at runtime. These messages can then be
56 enabled/disabled based on various levels of scope - per source file,
57 function, module, format string, and line number. This mechanism
58 implicitly compiles in all pr_debug() and dev_dbg() calls, which
59 enlarges the kernel text size by about 2%.
61 If a source file is compiled with DEBUG flag set, any
62 pr_debug() calls in it are enabled by default, but can be
63 disabled at runtime as below. Note that DEBUG flag is
64 turned on by many CONFIG_*DEBUG* options.
68 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
69 which is contained in the 'debugfs' filesystem. Thus, the debugfs
70 filesystem must first be mounted before making use of this feature.
71 We refer the control file as: <debugfs>/dynamic_debug/control. This
72 file contains a list of the debug statements that can be enabled. The
73 format for each line of the file is:
75 filename:lineno [module]function flags format
77 filename : source file of the debug statement
78 lineno : line number of the debug statement
79 module : module that contains the debug statement
80 function : function that contains the debug statement
81 flags : '=p' means the line is turned 'on' for printing
82 format : the format used for the debug statement
86 nullarbor:~ # cat <debugfs>/dynamic_debug/control
87 # filename:lineno [module]function flags format
88 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
89 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
90 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
94 // enable the message at line 1603 of file svcsock.c
95 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
96 <debugfs>/dynamic_debug/control
98 // enable all the messages in file svcsock.c
99 nullarbor:~ # echo -n 'file svcsock.c +p' >
100 <debugfs>/dynamic_debug/control
102 // enable all the messages in the NFS server module
103 nullarbor:~ # echo -n 'module nfsd +p' >
104 <debugfs>/dynamic_debug/control
106 // enable all 12 messages in the function svc_process()
107 nullarbor:~ # echo -n 'func svc_process +p' >
108 <debugfs>/dynamic_debug/control
110 // disable all 12 messages in the function svc_process()
111 nullarbor:~ # echo -n 'func svc_process -p' >
112 <debugfs>/dynamic_debug/control
114 See Documentation/dynamic-debug-howto.txt for additional information.
116 endmenu # "printk and dmesg options"
118 menu "Compile-time checks and compiler options"
121 bool "Compile the kernel with debug info"
122 depends on DEBUG_KERNEL && !COMPILE_TEST
124 If you say Y here the resulting kernel image will include
125 debugging info resulting in a larger kernel image.
126 This adds debug symbols to the kernel and modules (gcc -g), and
127 is needed if you intend to use kernel crashdump or binary object
128 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
129 Say Y here only if you plan to debug the kernel.
133 config DEBUG_INFO_REDUCED
134 bool "Reduce debugging information"
135 depends on DEBUG_INFO
137 If you say Y here gcc is instructed to generate less debugging
138 information for structure types. This means that tools that
139 need full debugging information (like kgdb or systemtap) won't
140 be happy. But if you merely need debugging information to
141 resolve line numbers there is no loss. Advantage is that
142 build directory object sizes shrink dramatically over a full
143 DEBUG_INFO build and compile times are reduced too.
144 Only works with newer gcc versions.
146 config DEBUG_INFO_SPLIT
147 bool "Produce split debuginfo in .dwo files"
148 depends on DEBUG_INFO
150 Generate debug info into separate .dwo files. This significantly
151 reduces the build directory size for builds with DEBUG_INFO,
152 because it stores the information only once on disk in .dwo
153 files instead of multiple times in object files and executables.
154 In addition the debug information is also compressed.
156 Requires recent gcc (4.7+) and recent gdb/binutils.
157 Any tool that packages or reads debug information would need
158 to know about the .dwo files and include them.
159 Incompatible with older versions of ccache.
161 config DEBUG_INFO_DWARF4
162 bool "Generate dwarf4 debuginfo"
163 depends on DEBUG_INFO
165 Generate dwarf4 debug info. This requires recent versions
166 of gcc and gdb. It makes the debug information larger.
167 But it significantly improves the success of resolving
168 variables in gdb on optimized code.
171 bool "Provide GDB scripts for kernel debugging"
172 depends on DEBUG_INFO
174 This creates the required links to GDB helper scripts in the
175 build directory. If you load vmlinux into gdb, the helper
176 scripts will be automatically imported by gdb as well, and
177 additional functions are available to analyze a Linux kernel
178 instance. See Documentation/gdb-kernel-debugging.txt for further
181 config ENABLE_WARN_DEPRECATED
182 bool "Enable __deprecated logic"
185 Enable the __deprecated logic in the kernel build.
186 Disable this to suppress the "warning: 'foo' is deprecated
187 (declared at kernel/power/somefile.c:1234)" messages.
189 config ENABLE_MUST_CHECK
190 bool "Enable __must_check logic"
193 Enable the __must_check logic in the kernel build. Disable this to
194 suppress the "warning: ignoring return value of 'foo', declared with
195 attribute warn_unused_result" messages.
198 int "Warn for stack frames larger than (needs gcc 4.4)"
201 default 1024 if !64BIT
202 default 2048 if 64BIT
204 Tell gcc to warn at build time for stack frames larger than this.
205 Setting this too low will cause a lot of warnings.
206 Setting it to 0 disables the warning.
209 config STRIP_ASM_SYMS
210 bool "Strip assembler-generated symbols during link"
213 Strip internal assembler-generated symbols during a link (symbols
214 that look like '.Lxxx') so they don't pollute the output of
215 get_wchan() and suchlike.
218 bool "Generate readable assembler code"
219 depends on DEBUG_KERNEL
221 Disable some compiler optimizations that tend to generate human unreadable
222 assembler output. This may make the kernel slightly slower, but it helps
223 to keep kernel developers who have to stare a lot at assembler listings
226 config UNUSED_SYMBOLS
227 bool "Enable unused/obsolete exported symbols"
230 Unused but exported symbols make the kernel needlessly bigger. For
231 that reason most of these unused exports will soon be removed. This
232 option is provided temporarily to provide a transition period in case
233 some external kernel module needs one of these symbols anyway. If you
234 encounter such a case in your module, consider if you are actually
235 using the right API. (rationale: since nobody in the kernel is using
236 this in a module, there is a pretty good chance it's actually the
237 wrong interface to use). If you really need the symbol, please send a
238 mail to the linux kernel mailing list mentioning the symbol and why
239 you really need it, and what the merge plan to the mainline kernel for
243 bool "Track page owner"
244 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
247 select PAGE_EXTENSION
249 This keeps track of what call chain is the owner of a page, may
250 help to find bare alloc_page(s) leaks. Even if you include this
251 feature on your build, it is disabled in default. You should pass
252 "page_owner=on" to boot parameter in order to enable it. Eats
253 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
254 for user-space helper.
259 bool "Debug Filesystem"
261 debugfs is a virtual file system that kernel developers use to put
262 debugging files into. Enable this option to be able to read and
263 write to these files.
265 For detailed documentation on the debugfs API, see
266 Documentation/DocBook/filesystems.
271 bool "Run 'make headers_check' when building vmlinux"
274 This option will extract the user-visible kernel headers whenever
275 building the kernel, and will run basic sanity checks on them to
276 ensure that exported files do not attempt to include files which
277 were not exported, etc.
279 If you're making modifications to header files which are
280 relevant for userspace, say 'Y', and check the headers
281 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
282 your build tree), to make sure they're suitable.
284 config DEBUG_SECTION_MISMATCH
285 bool "Enable full Section mismatch analysis"
287 The section mismatch analysis checks if there are illegal
288 references from one section to another section.
289 During linktime or runtime, some sections are dropped;
290 any use of code/data previously in these sections would
291 most likely result in an oops.
292 In the code, functions and variables are annotated with
293 __init,, etc. (see the full list in include/linux/init.h),
294 which results in the code/data being placed in specific sections.
295 The section mismatch analysis is always performed after a full
296 kernel build, and enabling this option causes the following
297 additional steps to occur:
298 - Add the option -fno-inline-functions-called-once to gcc commands.
299 When inlining a function annotated with __init in a non-init
300 function, we would lose the section information and thus
301 the analysis would not catch the illegal reference.
302 This option tells gcc to inline less (but it does result in
304 - Run the section mismatch analysis for each module/built-in.o file.
305 When we run the section mismatch analysis on vmlinux.o, we
306 lose valueble information about where the mismatch was
308 Running the analysis for each module/built-in.o file
309 tells where the mismatch happens much closer to the
310 source. The drawback is that the same mismatch is
311 reported at least twice.
312 - Enable verbose reporting from modpost in order to help resolve
313 the section mismatches that are reported.
315 config SECTION_MISMATCH_WARN_ONLY
316 bool "Make section mismatch errors non-fatal"
319 If you say N here, the build process will fail if there are any
320 section mismatch, instead of just throwing warnings.
325 # Select this config option from the architecture Kconfig, if it
326 # is preferred to always offer frame pointers as a config
327 # option on the architecture (regardless of KERNEL_DEBUG):
329 config ARCH_WANT_FRAME_POINTERS
334 bool "Compile the kernel with frame pointers"
335 depends on DEBUG_KERNEL && \
336 (CRIS || M68K || FRV || UML || \
337 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
338 ARCH_WANT_FRAME_POINTERS
339 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
341 If you say Y here the resulting kernel image will be slightly
342 larger and slower, but it gives very useful debugging information
343 in case of kernel bugs. (precise oopses/stacktraces/warnings)
345 config DEBUG_FORCE_WEAK_PER_CPU
346 bool "Force weak per-cpu definitions"
347 depends on DEBUG_KERNEL
349 s390 and alpha require percpu variables in modules to be
350 defined weak to work around addressing range issue which
351 puts the following two restrictions on percpu variable
354 1. percpu symbols must be unique whether static or not
355 2. percpu variables can't be defined inside a function
357 To ensure that generic code follows the above rules, this
358 option forces all percpu variables to be defined as weak.
360 endmenu # "Compiler options"
363 bool "Magic SysRq key"
366 If you say Y here, you will have some control over the system even
367 if the system crashes for example during kernel debugging (e.g., you
368 will be able to flush the buffer cache to disk, reboot the system
369 immediately or dump some status information). This is accomplished
370 by pressing various keys while holding SysRq (Alt+PrintScreen). It
371 also works on a serial console (on PC hardware at least), if you
372 send a BREAK and then within 5 seconds a command keypress. The
373 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
374 unless you really know what this hack does.
376 config MAGIC_SYSRQ_DEFAULT_ENABLE
377 hex "Enable magic SysRq key functions by default"
378 depends on MAGIC_SYSRQ
381 Specifies which SysRq key functions are enabled by default.
382 This may be set to 1 or 0 to enable or disable them all, or
383 to a bitmask as described in Documentation/sysrq.txt.
386 bool "Kernel debugging"
388 Say Y here if you are developing drivers or trying to debug and
389 identify kernel problems.
391 menu "Memory Debugging"
393 source mm/Kconfig.debug
396 bool "Debug object operations"
397 depends on DEBUG_KERNEL
399 If you say Y here, additional code will be inserted into the
400 kernel to track the life time of various objects and validate
401 the operations on those objects.
403 config DEBUG_OBJECTS_SELFTEST
404 bool "Debug objects selftest"
405 depends on DEBUG_OBJECTS
407 This enables the selftest of the object debug code.
409 config DEBUG_OBJECTS_FREE
410 bool "Debug objects in freed memory"
411 depends on DEBUG_OBJECTS
413 This enables checks whether a k/v free operation frees an area
414 which contains an object which has not been deactivated
415 properly. This can make kmalloc/kfree-intensive workloads
418 config DEBUG_OBJECTS_TIMERS
419 bool "Debug timer objects"
420 depends on DEBUG_OBJECTS
422 If you say Y here, additional code will be inserted into the
423 timer routines to track the life time of timer objects and
424 validate the timer operations.
426 config DEBUG_OBJECTS_WORK
427 bool "Debug work objects"
428 depends on DEBUG_OBJECTS
430 If you say Y here, additional code will be inserted into the
431 work queue routines to track the life time of work objects and
432 validate the work operations.
434 config DEBUG_OBJECTS_RCU_HEAD
435 bool "Debug RCU callbacks objects"
436 depends on DEBUG_OBJECTS
438 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
440 config DEBUG_OBJECTS_PERCPU_COUNTER
441 bool "Debug percpu counter objects"
442 depends on DEBUG_OBJECTS
444 If you say Y here, additional code will be inserted into the
445 percpu counter routines to track the life time of percpu counter
446 objects and validate the percpu counter operations.
448 config DEBUG_OBJECTS_ENABLE_DEFAULT
449 int "debug_objects bootup default value (0-1)"
452 depends on DEBUG_OBJECTS
454 Debug objects boot parameter default value
457 bool "Debug slab memory allocations"
458 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
460 Say Y here to have the kernel do limited verification on memory
461 allocation as well as poisoning memory on free to catch use of freed
462 memory. This can make kmalloc/kfree-intensive workloads much slower.
464 config DEBUG_SLAB_LEAK
465 bool "Memory leak debugging"
466 depends on DEBUG_SLAB
469 bool "SLUB debugging on by default"
470 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
473 Boot with debugging on by default. SLUB boots by default with
474 the runtime debug capabilities switched off. Enabling this is
475 equivalent to specifying the "slub_debug" parameter on boot.
476 There is no support for more fine grained debug control like
477 possible with slub_debug=xxx. SLUB debugging may be switched
478 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
483 bool "Enable SLUB performance statistics"
484 depends on SLUB && SYSFS
486 SLUB statistics are useful to debug SLUBs allocation behavior in
487 order find ways to optimize the allocator. This should never be
488 enabled for production use since keeping statistics slows down
489 the allocator by a few percentage points. The slabinfo command
490 supports the determination of the most active slabs to figure
491 out which slabs are relevant to a particular load.
492 Try running: slabinfo -DA
494 config HAVE_DEBUG_KMEMLEAK
497 config DEBUG_KMEMLEAK
498 bool "Kernel memory leak detector"
499 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
501 select STACKTRACE if STACKTRACE_SUPPORT
505 Say Y here if you want to enable the memory leak
506 detector. The memory allocation/freeing is traced in a way
507 similar to the Boehm's conservative garbage collector, the
508 difference being that the orphan objects are not freed but
509 only shown in /sys/kernel/debug/kmemleak. Enabling this
510 feature will introduce an overhead to memory
511 allocations. See Documentation/kmemleak.txt for more
514 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
515 of finding leaks due to the slab objects poisoning.
517 In order to access the kmemleak file, debugfs needs to be
518 mounted (usually at /sys/kernel/debug).
520 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
521 int "Maximum kmemleak early log entries"
522 depends on DEBUG_KMEMLEAK
526 Kmemleak must track all the memory allocations to avoid
527 reporting false positives. Since memory may be allocated or
528 freed before kmemleak is initialised, an early log buffer is
529 used to store these actions. If kmemleak reports "early log
530 buffer exceeded", please increase this value.
532 config DEBUG_KMEMLEAK_TEST
533 tristate "Simple test for the kernel memory leak detector"
534 depends on DEBUG_KMEMLEAK && m
536 This option enables a module that explicitly leaks memory.
540 config DEBUG_KMEMLEAK_DEFAULT_OFF
541 bool "Default kmemleak to off"
542 depends on DEBUG_KMEMLEAK
544 Say Y here to disable kmemleak by default. It can then be enabled
545 on the command line via kmemleak=on.
547 config DEBUG_KMEMLEAK_SCAN_ON
548 bool "Enable kmemleak auto scan thread on boot up"
550 depends on DEBUG_KMEMLEAK
552 Kmemleak scan is cpu intensive and can stall user tasks at times.
553 Say N here to disable kmemleak auto scan thread at boot up.
555 config DEBUG_STACK_USAGE
556 bool "Stack utilization instrumentation"
557 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
559 Enables the display of the minimum amount of free stack which each
560 task has ever had available in the sysrq-T and sysrq-P debug output.
562 This option will slow down process creation somewhat.
566 depends on DEBUG_KERNEL
568 Enable this to turn on extended checks in the virtual-memory system
569 that may impact performance.
573 config DEBUG_VM_VMACACHE
574 bool "Debug VMA caching"
577 Enable this to turn on VMA caching debug information. Doing so
578 can cause significant overhead, so only enable it in non-production
584 bool "Debug VM red-black trees"
587 Enable VM red-black tree debugging information and extra validations.
592 bool "Debug VM translations"
593 depends on DEBUG_KERNEL && X86
595 Enable some costly sanity checks in virtual to page code. This can
596 catch mistakes with virt_to_page() and friends.
600 config DEBUG_NOMMU_REGIONS
601 bool "Debug the global anon/private NOMMU mapping region tree"
602 depends on DEBUG_KERNEL && !MMU
604 This option causes the global tree of anonymous and private mapping
605 regions to be regularly checked for invalid topology.
607 config DEBUG_MEMORY_INIT
608 bool "Debug memory initialisation" if EXPERT
611 Enable this for additional checks during memory initialisation.
612 The sanity checks verify aspects of the VM such as the memory model
613 and other information provided by the architecture. Verbose
614 information will be printed at KERN_DEBUG loglevel depending
615 on the mminit_loglevel= command-line option.
619 config MEMORY_NOTIFIER_ERROR_INJECT
620 tristate "Memory hotplug notifier error injection module"
621 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
623 This option provides the ability to inject artificial errors to
624 memory hotplug notifier chain callbacks. It is controlled through
625 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
627 If the notifier call chain should be failed with some events
628 notified, write the error code to "actions/<notifier event>/error".
630 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
632 # cd /sys/kernel/debug/notifier-error-inject/memory
633 # echo -12 > actions/MEM_GOING_OFFLINE/error
634 # echo offline > /sys/devices/system/memory/memoryXXX/state
635 bash: echo: write error: Cannot allocate memory
637 To compile this code as a module, choose M here: the module will
638 be called memory-notifier-error-inject.
642 config DEBUG_PER_CPU_MAPS
643 bool "Debug access to per_cpu maps"
644 depends on DEBUG_KERNEL
647 Say Y to verify that the per_cpu map being accessed has
648 been set up. This adds a fair amount of code to kernel memory
649 and decreases performance.
654 bool "Highmem debugging"
655 depends on DEBUG_KERNEL && HIGHMEM
657 This option enables additional error checking for high memory
658 systems. Disable for production systems.
660 config HAVE_DEBUG_STACKOVERFLOW
663 config DEBUG_STACKOVERFLOW
664 bool "Check for stack overflows"
665 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
667 Say Y here if you want to check for overflows of kernel, IRQ
668 and exception stacks (if your architecture uses them). This
669 option will show detailed messages if free stack space drops
670 below a certain limit.
672 These kinds of bugs usually occur when call-chains in the
673 kernel get too deep, especially when interrupts are
676 Use this in cases where you see apparently random memory
677 corruption, especially if it appears in 'struct thread_info'
679 If in doubt, say "N".
681 source "lib/Kconfig.kmemcheck"
683 source "lib/Kconfig.kasan"
685 endmenu # "Memory Debugging"
688 bool "Compile with -O1 for debugging"
689 depends on DEBUG_KERNEL
690 default y if TEGRA_SIMULATION_PLATFORM
691 default n if !TEGRA_SIMULATION_PLATFORM
694 bool "Debug shared IRQ handlers"
695 depends on DEBUG_KERNEL
697 Enable this to generate a spurious interrupt as soon as a shared
698 interrupt handler is registered, and just before one is deregistered.
699 Drivers ought to be able to handle interrupts coming in at those
700 points; some don't and need to be caught.
702 menu "Debug Lockups and Hangs"
704 config LOCKUP_DETECTOR
705 bool "Detect Hard and Soft Lockups"
706 depends on DEBUG_KERNEL && !S390
708 Say Y here to enable the kernel to act as a watchdog to detect
709 hard and soft lockups.
711 Softlockups are bugs that cause the kernel to loop in kernel
712 mode for more than 20 seconds, without giving other tasks a
713 chance to run. The current stack trace is displayed upon
714 detection and the system will stay locked up.
716 Hardlockups are bugs that cause the CPU to loop in kernel mode
717 for more than 10 seconds, without letting other interrupts have a
718 chance to run. The current stack trace is displayed upon detection
719 and the system will stay locked up.
721 The overhead should be minimal. A periodic hrtimer runs to
722 generate interrupts and kick the watchdog task every 4 seconds.
723 An NMI is generated every 10 seconds or so to check for hardlockups.
724 If NMIs are not available on the platform, every 12 seconds the
725 hrtimer interrupt on one cpu will be used to check for hardlockups
728 The frequency of hrtimer and NMI events and the soft and hard lockup
729 thresholds can be controlled through the sysctl watchdog_thresh.
731 config HARDLOCKUP_DETECTOR_NMI
733 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
734 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
736 config HARDLOCKUP_DETECTOR_OTHER_CPU
738 depends on LOCKUP_DETECTOR && SMP
739 depends on !HARDLOCKUP_DETECTOR_NMI && !HAVE_NMI_WATCHDOG
741 config HARDLOCKUP_DETECTOR
743 depends on HARDLOCKUP_DETECTOR_NMI || HARDLOCKUP_DETECTOR_OTHER_CPU
745 config BOOTPARAM_HARDLOCKUP_PANIC
746 bool "Panic (Reboot) On Hard Lockups"
747 depends on HARDLOCKUP_DETECTOR
749 Say Y here to enable the kernel to panic on "hard lockups",
750 which are bugs that cause the kernel to loop in kernel
751 mode with interrupts disabled for more than 10 seconds (configurable
752 using the watchdog_thresh sysctl).
756 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
758 depends on HARDLOCKUP_DETECTOR
760 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
761 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
763 config BOOTPARAM_SOFTLOCKUP_PANIC
764 bool "Panic (Reboot) On Soft Lockups"
765 depends on LOCKUP_DETECTOR
767 Say Y here to enable the kernel to panic on "soft lockups",
768 which are bugs that cause the kernel to loop in kernel
769 mode for more than 20 seconds (configurable using the watchdog_thresh
770 sysctl), without giving other tasks a chance to run.
772 The panic can be used in combination with panic_timeout,
773 to cause the system to reboot automatically after a
774 lockup has been detected. This feature is useful for
775 high-availability systems that have uptime guarantees and
776 where a lockup must be resolved ASAP.
780 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
782 depends on LOCKUP_DETECTOR
784 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
785 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
787 config DETECT_HUNG_TASK
788 bool "Detect Hung Tasks"
789 depends on DEBUG_KERNEL
790 default LOCKUP_DETECTOR
792 Say Y here to enable the kernel to detect "hung tasks",
793 which are bugs that cause the task to be stuck in
794 uninterruptible "D" state indefinitiley.
796 When a hung task is detected, the kernel will print the
797 current stack trace (which you should report), but the
798 task will stay in uninterruptible state. If lockdep is
799 enabled then all held locks will also be reported. This
800 feature has negligible overhead.
802 config DEFAULT_HUNG_TASK_TIMEOUT
803 int "Default timeout for hung task detection (in seconds)"
804 depends on DETECT_HUNG_TASK
807 This option controls the default timeout (in seconds) used
808 to determine when a task has become non-responsive and should
811 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
812 sysctl or by writing a value to
813 /proc/sys/kernel/hung_task_timeout_secs.
815 A timeout of 0 disables the check. The default is two minutes.
816 Keeping the default should be fine in most cases.
818 config BOOTPARAM_HUNG_TASK_PANIC
819 bool "Panic (Reboot) On Hung Tasks"
820 depends on DETECT_HUNG_TASK
822 Say Y here to enable the kernel to panic on "hung tasks",
823 which are bugs that cause the kernel to leave a task stuck
824 in uninterruptible "D" state.
826 The panic can be used in combination with panic_timeout,
827 to cause the system to reboot automatically after a
828 hung task has been detected. This feature is useful for
829 high-availability systems that have uptime guarantees and
830 where a hung tasks must be resolved ASAP.
834 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
836 depends on DETECT_HUNG_TASK
838 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
839 default 1 if BOOTPARAM_HUNG_TASK_PANIC
841 endmenu # "Debug lockups and hangs"
846 Say Y here to enable the kernel to panic when it oopses. This
847 has the same effect as setting oops=panic on the kernel command
850 This feature is useful to ensure that the kernel does not do
851 anything erroneous after an oops which could result in data
852 corruption or other issues.
856 config PANIC_ON_OOPS_VALUE
859 default 0 if !PANIC_ON_OOPS
860 default 1 if PANIC_ON_OOPS
866 Set the timeout value (in seconds) until a reboot occurs when the
867 the kernel panics. If n = 0, then we wait forever. A timeout
868 value n > 0 will wait n seconds before rebooting, while a timeout
869 value n < 0 will reboot immediately.
872 bool "Collect scheduler debugging info"
873 depends on DEBUG_KERNEL && PROC_FS
876 If you say Y here, the /proc/sched_debug file will be provided
877 that can help debug the scheduler. The runtime overhead of this
885 bool "Collect scheduler statistics"
886 depends on DEBUG_KERNEL && PROC_FS
889 If you say Y here, additional code will be inserted into the
890 scheduler and related routines to collect statistics about
891 scheduler behavior and provide them in /proc/schedstat. These
892 stats may be useful for both tuning and debugging the scheduler
893 If you aren't debugging the scheduler or trying to tune a specific
894 application, you can say N to avoid the very slight overhead
897 config SCHED_STACK_END_CHECK
898 bool "Detect stack corruption on calls to schedule()"
899 depends on DEBUG_KERNEL
902 This option checks for a stack overrun on calls to schedule().
903 If the stack end location is found to be over written always panic as
904 the content of the corrupted region can no longer be trusted.
905 This is to ensure no erroneous behaviour occurs which could result in
906 data corruption or a sporadic crash at a later stage once the region
907 is examined. The runtime overhead introduced is minimal.
909 config DEBUG_TIMEKEEPING
910 bool "Enable extra timekeeping sanity checking"
912 This option will enable additional timekeeping sanity checks
913 which may be helpful when diagnosing issues where timekeeping
914 problems are suspected.
916 This may include checks in the timekeeping hotpaths, so this
917 option may have a (very small) performance impact to some
923 bool "Collect kernel timers statistics"
924 depends on DEBUG_KERNEL && PROC_FS
926 If you say Y here, additional code will be inserted into the
927 timer routines to collect statistics about kernel timers being
928 reprogrammed. The statistics can be read from /proc/timer_stats.
929 The statistics collection is started by writing 1 to /proc/timer_stats,
930 writing 0 stops it. This feature is useful to collect information
931 about timer usage patterns in kernel and userspace. This feature
932 is lightweight if enabled in the kernel config but not activated
933 (it defaults to deactivated on bootup and will only be activated
934 if some application like powertop activates it explicitly).
937 bool "Debug preemptible kernel"
938 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
941 If you say Y here then the kernel will use a debug variant of the
942 commonly used smp_processor_id() function and will print warnings
943 if kernel code uses it in a preemption-unsafe way. Also, the kernel
944 will detect preemption count underflows.
946 menu "Lock Debugging (spinlocks, mutexes, etc...)"
948 config DEBUG_RT_MUTEXES
949 bool "RT Mutex debugging, deadlock detection"
950 depends on DEBUG_KERNEL && RT_MUTEXES
952 This allows rt mutex semantics violations and rt mutex related
953 deadlocks (lockups) to be detected and reported automatically.
955 config DEBUG_SPINLOCK
956 bool "Spinlock and rw-lock debugging: basic checks"
957 depends on DEBUG_KERNEL
958 select UNINLINE_SPIN_UNLOCK
960 Say Y here and build SMP to catch missing spinlock initialization
961 and certain other kinds of spinlock errors commonly made. This is
962 best used in conjunction with the NMI watchdog so that spinlock
963 deadlocks are also debuggable.
966 bool "Mutex debugging: basic checks"
967 depends on DEBUG_KERNEL
969 This feature allows mutex semantics violations to be detected and
972 config DEBUG_WW_MUTEX_SLOWPATH
973 bool "Wait/wound mutex debugging: Slowpath testing"
974 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
975 select DEBUG_LOCK_ALLOC
976 select DEBUG_SPINLOCK
979 This feature enables slowpath testing for w/w mutex users by
980 injecting additional -EDEADLK wound/backoff cases. Together with
981 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
982 will test all possible w/w mutex interface abuse with the
983 exception of simply not acquiring all the required locks.
984 Note that this feature can introduce significant overhead, so
985 it really should not be enabled in a production or distro kernel,
986 even a debug kernel. If you are a driver writer, enable it. If
987 you are a distro, do not.
989 config DEBUG_LOCK_ALLOC
990 bool "Lock debugging: detect incorrect freeing of live locks"
991 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
992 select DEBUG_SPINLOCK
996 This feature will check whether any held lock (spinlock, rwlock,
997 mutex or rwsem) is incorrectly freed by the kernel, via any of the
998 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
999 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1000 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1001 held during task exit.
1003 config PROVE_LOCKING
1004 bool "Lock debugging: prove locking correctness"
1005 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1007 select DEBUG_SPINLOCK
1008 select DEBUG_MUTEXES
1009 select DEBUG_LOCK_ALLOC
1010 select TRACE_IRQFLAGS
1013 This feature enables the kernel to prove that all locking
1014 that occurs in the kernel runtime is mathematically
1015 correct: that under no circumstance could an arbitrary (and
1016 not yet triggered) combination of observed locking
1017 sequences (on an arbitrary number of CPUs, running an
1018 arbitrary number of tasks and interrupt contexts) cause a
1021 In short, this feature enables the kernel to report locking
1022 related deadlocks before they actually occur.
1024 The proof does not depend on how hard and complex a
1025 deadlock scenario would be to trigger: how many
1026 participant CPUs, tasks and irq-contexts would be needed
1027 for it to trigger. The proof also does not depend on
1028 timing: if a race and a resulting deadlock is possible
1029 theoretically (no matter how unlikely the race scenario
1030 is), it will be proven so and will immediately be
1031 reported by the kernel (once the event is observed that
1032 makes the deadlock theoretically possible).
1034 If a deadlock is impossible (i.e. the locking rules, as
1035 observed by the kernel, are mathematically correct), the
1036 kernel reports nothing.
1038 NOTE: this feature can also be enabled for rwlocks, mutexes
1039 and rwsems - in which case all dependencies between these
1040 different locking variants are observed and mapped too, and
1041 the proof of observed correctness is also maintained for an
1042 arbitrary combination of these separate locking variants.
1044 For more details, see Documentation/locking/lockdep-design.txt.
1048 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1050 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
1055 bool "Lock usage statistics"
1056 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1058 select DEBUG_SPINLOCK
1059 select DEBUG_MUTEXES
1060 select DEBUG_LOCK_ALLOC
1063 This feature enables tracking lock contention points
1065 For more details, see Documentation/locking/lockstat.txt
1067 This also enables lock events required by "perf lock",
1069 If you want to use "perf lock", you also need to turn on
1070 CONFIG_EVENT_TRACING.
1072 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1073 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1075 config DEBUG_LOCKDEP
1076 bool "Lock dependency engine debugging"
1077 depends on DEBUG_KERNEL && LOCKDEP
1079 If you say Y here, the lock dependency engine will do
1080 additional runtime checks to debug itself, at the price
1081 of more runtime overhead.
1083 config DEBUG_ATOMIC_SLEEP
1084 bool "Sleep inside atomic section checking"
1085 select PREEMPT_COUNT
1086 depends on DEBUG_KERNEL
1088 If you say Y here, various routines which may sleep will become very
1089 noisy if they are called inside atomic sections: when a spinlock is
1090 held, inside an rcu read side critical section, inside preempt disabled
1091 sections, inside an interrupt, etc...
1093 config DEBUG_LOCKING_API_SELFTESTS
1094 bool "Locking API boot-time self-tests"
1095 depends on DEBUG_KERNEL
1097 Say Y here if you want the kernel to run a short self-test during
1098 bootup. The self-test checks whether common types of locking bugs
1099 are detected by debugging mechanisms or not. (if you disable
1100 lock debugging then those bugs wont be detected of course.)
1101 The following locking APIs are covered: spinlocks, rwlocks,
1104 config LOCK_TORTURE_TEST
1105 tristate "torture tests for locking"
1106 depends on DEBUG_KERNEL
1110 This option provides a kernel module that runs torture tests
1111 on kernel locking primitives. The kernel module may be built
1112 after the fact on the running kernel to be tested, if desired.
1114 Say Y here if you want kernel locking-primitive torture tests
1115 to be built into the kernel.
1116 Say M if you want these torture tests to build as a module.
1117 Say N if you are unsure.
1119 endmenu # lock debugging
1121 config TRACE_IRQFLAGS
1124 Enables hooks to interrupt enabling and disabling for
1125 either tracing or lock debugging.
1128 bool "Stack backtrace support"
1129 depends on STACKTRACE_SUPPORT
1131 This option causes the kernel to create a /proc/pid/stack for
1132 every process, showing its current stack trace.
1133 It is also used by various kernel debugging features that require
1134 stack trace generation.
1136 config DEBUG_KOBJECT
1137 bool "kobject debugging"
1138 depends on DEBUG_KERNEL
1140 If you say Y here, some extra kobject debugging messages will be sent
1143 config DEBUG_KOBJECT_RELEASE
1144 bool "kobject release debugging"
1145 depends on DEBUG_OBJECTS_TIMERS
1147 kobjects are reference counted objects. This means that their
1148 last reference count put is not predictable, and the kobject can
1149 live on past the point at which a driver decides to drop it's
1150 initial reference to the kobject gained on allocation. An
1151 example of this would be a struct device which has just been
1154 However, some buggy drivers assume that after such an operation,
1155 the memory backing the kobject can be immediately freed. This
1156 goes completely against the principles of a refcounted object.
1158 If you say Y here, the kernel will delay the release of kobjects
1159 on the last reference count to improve the visibility of this
1160 kind of kobject release bug.
1162 config HAVE_DEBUG_BUGVERBOSE
1165 config DEBUG_BUGVERBOSE
1166 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1167 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1170 Say Y here to make BUG() panics output the file name and line number
1171 of the BUG call as well as the EIP and oops trace. This aids
1172 debugging but costs about 70-100K of memory.
1175 bool "Debug linked list manipulation"
1176 depends on DEBUG_KERNEL
1178 Enable this to turn on extended checks in the linked-list
1183 config DEBUG_PI_LIST
1184 bool "Debug priority linked list manipulation"
1185 depends on DEBUG_KERNEL
1187 Enable this to turn on extended checks in the priority-ordered
1188 linked-list (plist) walking routines. This checks the entire
1189 list multiple times during each manipulation.
1194 bool "Debug SG table operations"
1195 depends on DEBUG_KERNEL
1197 Enable this to turn on checks on scatter-gather tables. This can
1198 help find problems with drivers that do not properly initialize
1203 config DEBUG_NOTIFIERS
1204 bool "Debug notifier call chains"
1205 depends on DEBUG_KERNEL
1207 Enable this to turn on sanity checking for notifier call chains.
1208 This is most useful for kernel developers to make sure that
1209 modules properly unregister themselves from notifier chains.
1210 This is a relatively cheap check but if you care about maximum
1213 config DEBUG_CREDENTIALS
1214 bool "Debug credential management"
1215 depends on DEBUG_KERNEL
1217 Enable this to turn on some debug checking for credential
1218 management. The additional code keeps track of the number of
1219 pointers from task_structs to any given cred struct, and checks to
1220 see that this number never exceeds the usage count of the cred
1223 Furthermore, if SELinux is enabled, this also checks that the
1224 security pointer in the cred struct is never seen to be invalid.
1228 menu "RCU Debugging"
1231 def_bool PROVE_LOCKING
1233 config PROVE_RCU_REPEATEDLY
1234 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1235 depends on PROVE_RCU
1238 By itself, PROVE_RCU will disable checking upon issuing the
1239 first warning (or "splat"). This feature prevents such
1240 disabling, allowing multiple RCU-lockdep warnings to be printed
1243 Say Y to allow multiple RCU-lockdep warnings per boot.
1245 Say N if you are unsure.
1247 config SPARSE_RCU_POINTER
1248 bool "RCU debugging: sparse-based checks for pointer usage"
1251 This feature enables the __rcu sparse annotation for
1252 RCU-protected pointers. This annotation will cause sparse
1253 to flag any non-RCU used of annotated pointers. This can be
1254 helpful when debugging RCU usage. Please note that this feature
1255 is not intended to enforce code cleanliness; it is instead merely
1258 Say Y to make sparse flag questionable use of RCU-protected pointers
1260 Say N if you are unsure.
1266 config RCU_TORTURE_TEST
1267 tristate "torture tests for RCU"
1268 depends on DEBUG_KERNEL
1274 This option provides a kernel module that runs torture tests
1275 on the RCU infrastructure. The kernel module may be built
1276 after the fact on the running kernel to be tested, if desired.
1278 Say Y here if you want RCU torture tests to be built into
1280 Say M if you want the RCU torture tests to build as a module.
1281 Say N if you are unsure.
1283 config RCU_TORTURE_TEST_RUNNABLE
1284 bool "torture tests for RCU runnable by default"
1285 depends on RCU_TORTURE_TEST = y
1288 This option provides a way to build the RCU torture tests
1289 directly into the kernel without them starting up at boot
1290 time. You can use /proc/sys/kernel/rcutorture_runnable
1291 to manually override this setting. This /proc file is
1292 available only when the RCU torture tests have been built
1295 Say Y here if you want the RCU torture tests to start during
1296 boot (you probably don't).
1297 Say N here if you want the RCU torture tests to start only
1298 after being manually enabled via /proc.
1300 config RCU_TORTURE_TEST_SLOW_PREINIT
1301 bool "Slow down RCU grace-period pre-initialization to expose races"
1302 depends on RCU_TORTURE_TEST
1304 This option delays grace-period pre-initialization (the
1305 propagation of CPU-hotplug changes up the rcu_node combining
1306 tree) for a few jiffies between initializing each pair of
1307 consecutive rcu_node structures. This helps to expose races
1308 involving grace-period pre-initialization, in other words, it
1309 makes your kernel less stable. It can also greatly increase
1310 grace-period latency, especially on systems with large numbers
1311 of CPUs. This is useful when torture-testing RCU, but in
1312 almost no other circumstance.
1314 Say Y here if you want your system to crash and hang more often.
1315 Say N if you want a sane system.
1317 config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1318 int "How much to slow down RCU grace-period pre-initialization"
1321 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1323 This option specifies the number of jiffies to wait between
1324 each rcu_node structure pre-initialization step.
1326 config RCU_TORTURE_TEST_SLOW_INIT
1327 bool "Slow down RCU grace-period initialization to expose races"
1328 depends on RCU_TORTURE_TEST
1330 This option delays grace-period initialization for a few
1331 jiffies between initializing each pair of consecutive
1332 rcu_node structures. This helps to expose races involving
1333 grace-period initialization, in other words, it makes your
1334 kernel less stable. It can also greatly increase grace-period
1335 latency, especially on systems with large numbers of CPUs.
1336 This is useful when torture-testing RCU, but in almost no
1339 Say Y here if you want your system to crash and hang more often.
1340 Say N if you want a sane system.
1342 config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1343 int "How much to slow down RCU grace-period initialization"
1346 depends on RCU_TORTURE_TEST_SLOW_INIT
1348 This option specifies the number of jiffies to wait between
1349 each rcu_node structure initialization.
1351 config RCU_TORTURE_TEST_SLOW_CLEANUP
1352 bool "Slow down RCU grace-period cleanup to expose races"
1353 depends on RCU_TORTURE_TEST
1355 This option delays grace-period cleanup for a few jiffies
1356 between cleaning up each pair of consecutive rcu_node
1357 structures. This helps to expose races involving grace-period
1358 cleanup, in other words, it makes your kernel less stable.
1359 It can also greatly increase grace-period latency, especially
1360 on systems with large numbers of CPUs. This is useful when
1361 torture-testing RCU, but in almost no other circumstance.
1363 Say Y here if you want your system to crash and hang more often.
1364 Say N if you want a sane system.
1366 config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1367 int "How much to slow down RCU grace-period cleanup"
1370 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1372 This option specifies the number of jiffies to wait between
1373 each rcu_node structure cleanup operation.
1375 config RCU_CPU_STALL_TIMEOUT
1376 int "RCU CPU stall timeout in seconds"
1377 depends on RCU_STALL_COMMON
1381 If a given RCU grace period extends more than the specified
1382 number of seconds, a CPU stall warning is printed. If the
1383 RCU grace period persists, additional CPU stall warnings are
1384 printed at more widely spaced intervals.
1387 bool "Enable tracing for RCU"
1388 depends on DEBUG_KERNEL
1391 This option provides tracing in RCU which presents stats
1392 in debugfs for debugging RCU implementation.
1394 Say Y here if you want to enable RCU tracing
1395 Say N if you are unsure.
1397 config RCU_EQS_DEBUG
1398 bool "Provide debugging asserts for adding NO_HZ support to an arch"
1399 depends on DEBUG_KERNEL
1401 This option provides consistency checks in RCU's handling of
1402 NO_HZ. These checks have proven quite helpful in detecting
1403 bugs in arch-specific NO_HZ code.
1405 Say N here if you need ultimate kernel/user switch latencies
1406 Say Y if you are unsure
1408 endmenu # "RCU Debugging"
1410 config DEBUG_BLOCK_EXT_DEVT
1411 bool "Force extended block device numbers and spread them"
1412 depends on DEBUG_KERNEL
1416 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1417 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1418 YOU ARE DOING. Distros, please enable this and fix whatever
1421 Conventionally, block device numbers are allocated from
1422 predetermined contiguous area. However, extended block area
1423 may introduce non-contiguous block device numbers. This
1424 option forces most block device numbers to be allocated from
1425 the extended space and spreads them to discover kernel or
1426 userland code paths which assume predetermined contiguous
1427 device number allocation.
1429 Note that turning on this debug option shuffles all the
1430 device numbers for all IDE and SCSI devices including libata
1431 ones, so root partition specified using device number
1432 directly (via rdev or root=MAJ:MIN) won't work anymore.
1433 Textual device names (root=/dev/sdXn) will continue to work.
1435 Say N if you are unsure.
1437 config NOTIFIER_ERROR_INJECTION
1438 tristate "Notifier error injection"
1439 depends on DEBUG_KERNEL
1442 This option provides the ability to inject artificial errors to
1443 specified notifier chain callbacks. It is useful to test the error
1444 handling of notifier call chain failures.
1448 config CPU_NOTIFIER_ERROR_INJECT
1449 tristate "CPU notifier error injection module"
1450 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1452 This option provides a kernel module that can be used to test
1453 the error handling of the cpu notifiers by injecting artificial
1454 errors to CPU notifier chain callbacks. It is controlled through
1455 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1457 If the notifier call chain should be failed with some events
1458 notified, write the error code to "actions/<notifier event>/error".
1460 Example: Inject CPU offline error (-1 == -EPERM)
1462 # cd /sys/kernel/debug/notifier-error-inject/cpu
1463 # echo -1 > actions/CPU_DOWN_PREPARE/error
1464 # echo 0 > /sys/devices/system/cpu/cpu1/online
1465 bash: echo: write error: Operation not permitted
1467 To compile this code as a module, choose M here: the module will
1468 be called cpu-notifier-error-inject.
1472 config PM_NOTIFIER_ERROR_INJECT
1473 tristate "PM notifier error injection module"
1474 depends on PM && NOTIFIER_ERROR_INJECTION
1475 default m if PM_DEBUG
1477 This option provides the ability to inject artificial errors to
1478 PM notifier chain callbacks. It is controlled through debugfs
1479 interface /sys/kernel/debug/notifier-error-inject/pm
1481 If the notifier call chain should be failed with some events
1482 notified, write the error code to "actions/<notifier event>/error".
1484 Example: Inject PM suspend error (-12 = -ENOMEM)
1486 # cd /sys/kernel/debug/notifier-error-inject/pm/
1487 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1488 # echo mem > /sys/power/state
1489 bash: echo: write error: Cannot allocate memory
1491 To compile this code as a module, choose M here: the module will
1492 be called pm-notifier-error-inject.
1496 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1497 tristate "OF reconfig notifier error injection module"
1498 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1500 This option provides the ability to inject artificial errors to
1501 OF reconfig notifier chain callbacks. It is controlled
1502 through debugfs interface under
1503 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1505 If the notifier call chain should be failed with some events
1506 notified, write the error code to "actions/<notifier event>/error".
1508 To compile this code as a module, choose M here: the module will
1509 be called of-reconfig-notifier-error-inject.
1513 config FAULT_INJECTION
1514 bool "Fault-injection framework"
1515 depends on DEBUG_KERNEL
1517 Provide fault-injection framework.
1518 For more details, see Documentation/fault-injection/.
1521 bool "Fault-injection capability for kmalloc"
1522 depends on FAULT_INJECTION
1523 depends on SLAB || SLUB
1525 Provide fault-injection capability for kmalloc.
1527 config FAIL_PAGE_ALLOC
1528 bool "Fault-injection capabilitiy for alloc_pages()"
1529 depends on FAULT_INJECTION
1531 Provide fault-injection capability for alloc_pages().
1533 config FAIL_MAKE_REQUEST
1534 bool "Fault-injection capability for disk IO"
1535 depends on FAULT_INJECTION && BLOCK
1537 Provide fault-injection capability for disk IO.
1539 config FAIL_IO_TIMEOUT
1540 bool "Fault-injection capability for faking disk interrupts"
1541 depends on FAULT_INJECTION && BLOCK
1543 Provide fault-injection capability on end IO handling. This
1544 will make the block layer "forget" an interrupt as configured,
1545 thus exercising the error handling.
1547 Only works with drivers that use the generic timeout handling,
1548 for others it wont do anything.
1550 config FAIL_MMC_REQUEST
1551 bool "Fault-injection capability for MMC IO"
1553 depends on FAULT_INJECTION && MMC
1555 Provide fault-injection capability for MMC IO.
1556 This will make the mmc core return data errors. This is
1557 useful to test the error handling in the mmc block device
1558 and to test how the mmc host driver handles retries from
1562 bool "Fault-injection capability for futexes"
1564 depends on FAULT_INJECTION && FUTEX
1566 Provide fault-injection capability for futexes.
1568 config FAULT_INJECTION_DEBUG_FS
1569 bool "Debugfs entries for fault-injection capabilities"
1570 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1572 Enable configuration of fault-injection capabilities via debugfs.
1574 config FAULT_INJECTION_STACKTRACE_FILTER
1575 bool "stacktrace filter for fault-injection capabilities"
1576 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1579 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1581 Provide stacktrace filter for fault-injection capabilities
1584 bool "Latency measuring infrastructure"
1585 depends on HAVE_LATENCYTOP_SUPPORT
1586 depends on DEBUG_KERNEL
1587 depends on STACKTRACE_SUPPORT
1589 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1596 Enable this option if you want to use the LatencyTOP tool
1597 to find out which userspace is blocking on what kernel operations.
1599 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1602 config DEBUG_STRICT_USER_COPY_CHECKS
1603 bool "Strict user copy size checks"
1604 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1605 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1607 Enabling this option turns a certain set of sanity checks for user
1608 copy operations into compile time failures.
1610 The copy_from_user() etc checks are there to help test if there
1611 are sufficient security checks on the length argument of
1612 the copy operation, by having gcc prove that the argument is
1617 source kernel/trace/Kconfig
1619 menu "Runtime Testing"
1622 tristate "Linux Kernel Dump Test Tool Module"
1627 This module enables testing of the different dumping mechanisms by
1628 inducing system failures at predefined crash points.
1629 If you don't need it: say N
1630 Choose M here to compile this code as a module. The module will be
1633 Documentation on how to use the module can be found in
1634 Documentation/fault-injection/provoke-crashes.txt
1636 config TEST_LIST_SORT
1637 bool "Linked list sorting test"
1638 depends on DEBUG_KERNEL
1640 Enable this to turn on 'list_sort()' function test. This test is
1641 executed only once during system boot, so affects only boot time.
1645 config KPROBES_SANITY_TEST
1646 bool "Kprobes sanity tests"
1647 depends on DEBUG_KERNEL
1651 This option provides for testing basic kprobes functionality on
1652 boot. A sample kprobe, jprobe and kretprobe are inserted and
1653 verified for functionality.
1655 Say N if you are unsure.
1657 config BACKTRACE_SELF_TEST
1658 tristate "Self test for the backtrace code"
1659 depends on DEBUG_KERNEL
1662 This option provides a kernel module that can be used to test
1663 the kernel stack backtrace code. This option is not useful
1664 for distributions or general kernels, but only for kernel
1665 developers working on architecture code.
1667 Note that if you want to also test saved backtraces, you will
1668 have to enable STACKTRACE as well.
1670 Say N if you are unsure.
1673 tristate "Red-Black tree test"
1674 depends on DEBUG_KERNEL
1676 A benchmark measuring the performance of the rbtree library.
1677 Also includes rbtree invariant checks.
1679 config INTERVAL_TREE_TEST
1680 tristate "Interval tree test"
1681 depends on m && DEBUG_KERNEL
1682 select INTERVAL_TREE
1684 A benchmark measuring the performance of the interval tree library
1687 tristate "Per cpu operations test"
1688 depends on m && DEBUG_KERNEL
1690 Enable this option to build test module which validates per-cpu
1695 config ATOMIC64_SELFTEST
1696 bool "Perform an atomic64_t self-test at boot"
1698 Enable this option to test the atomic64_t functions at boot.
1702 config ASYNC_RAID6_TEST
1703 tristate "Self test for hardware accelerated raid6 recovery"
1704 depends on ASYNC_RAID6_RECOV
1707 This is a one-shot self test that permutes through the
1708 recovery of all the possible two disk failure scenarios for a
1709 N-disk array. Recovery is performed with the asynchronous
1710 raid6 recovery routines, and will optionally use an offload
1711 engine if one is available.
1716 tristate "Test functions located in the hexdump module at runtime"
1718 config TEST_STRING_HELPERS
1719 tristate "Test functions located in the string_helpers module at runtime"
1722 tristate "Test kstrto*() family of functions at runtime"
1725 tristate "Test printf() family of functions at runtime"
1727 config TEST_RHASHTABLE
1728 tristate "Perform selftest on resizable hash table"
1731 Enable this option to test the rhashtable functions at boot.
1735 endmenu # runtime tests
1737 config PROVIDE_OHCI1394_DMA_INIT
1738 bool "Remote debugging over FireWire early on boot"
1739 depends on PCI && X86
1741 If you want to debug problems which hang or crash the kernel early
1742 on boot and the crashing machine has a FireWire port, you can use
1743 this feature to remotely access the memory of the crashed machine
1744 over FireWire. This employs remote DMA as part of the OHCI1394
1745 specification which is now the standard for FireWire controllers.
1747 With remote DMA, you can monitor the printk buffer remotely using
1748 firescope and access all memory below 4GB using fireproxy from gdb.
1749 Even controlling a kernel debugger is possible using remote DMA.
1753 If ohci1394_dma=early is used as boot parameter, it will initialize
1754 all OHCI1394 controllers which are found in the PCI config space.
1756 As all changes to the FireWire bus such as enabling and disabling
1757 devices cause a bus reset and thereby disable remote DMA for all
1758 devices, be sure to have the cable plugged and FireWire enabled on
1759 the debugging host before booting the debug target for debugging.
1761 This code (~1k) is freed after boot. By then, the firewire stack
1762 in charge of the OHCI-1394 controllers should be used instead.
1764 See Documentation/debugging-via-ohci1394.txt for more information.
1767 bool "Build targets in Documentation/ tree"
1768 depends on HEADERS_CHECK
1770 This option attempts to build objects from the source files in the
1771 kernel Documentation/ tree.
1773 Say N if you are unsure.
1775 config DMA_API_DEBUG
1776 bool "Enable debugging of DMA-API usage"
1777 depends on HAVE_DMA_API_DEBUG
1779 Enable this option to debug the use of the DMA API by device drivers.
1780 With this option you will be able to detect common bugs in device
1781 drivers like double-freeing of DMA mappings or freeing mappings that
1782 were never allocated.
1784 This also attempts to catch cases where a page owned by DMA is
1785 accessed by the cpu in a way that could cause data corruption. For
1786 example, this enables cow_user_page() to check that the source page is
1789 This option causes a performance degradation. Use only if you want to
1790 debug device drivers and dma interactions.
1795 tristate "Test module loading with 'hello world' module"
1799 This builds the "test_module" module that emits "Hello, world"
1800 on printk when loaded. It is designed to be used for basic
1801 evaluation of the module loading subsystem (for example when
1802 validating module verification). It lacks any extra dependencies,
1803 and will not normally be loaded by the system unless explicitly
1808 config TEST_USER_COPY
1809 tristate "Test user/kernel boundary protections"
1813 This builds the "test_user_copy" module that runs sanity checks
1814 on the copy_to/from_user infrastructure, making sure basic
1815 user/kernel boundary testing is working. If it fails to load,
1816 a regression has been detected in the user/kernel memory boundary
1822 tristate "Test BPF filter functionality"
1826 This builds the "test_bpf" module that runs various test vectors
1827 against the BPF interpreter or BPF JIT compiler depending on the
1828 current setting. This is in particular useful for BPF JIT compiler
1829 development, but also to run regression tests against changes in
1830 the interpreter code. It also enables test stubs for eBPF maps and
1831 verifier used by user space verifier testsuite.
1835 config TEST_FIRMWARE
1836 tristate "Test firmware loading via userspace interface"
1838 depends on FW_LOADER
1840 This builds the "test_firmware" module that creates a userspace
1841 interface for testing firmware loading. This can be used to
1842 control the triggering of firmware loading without needing an
1843 actual firmware-using device. The contents can be rechecked by
1849 tristate "udelay test driver"
1852 This builds the "udelay_test" module that helps to make sure
1853 that udelay() is working properly.
1859 depends on HAVE_MEMBLOCK
1861 This option adds a kernel parameter 'memtest', which allows memtest
1863 memtest=0, mean disabled; -- default
1864 memtest=1, mean do 1 test pattern;
1866 memtest=17, mean do 17 test patterns.
1867 If you are unsure how to answer this question, answer N.
1869 config TEST_STATIC_KEYS
1870 tristate "Test static keys"
1874 Test the static key interfaces.
1878 source "samples/Kconfig"
1880 source "lib/Kconfig.kgdb"
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