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.
170 config ENABLE_WARN_DEPRECATED
171 bool "Enable __deprecated logic"
174 Enable the __deprecated logic in the kernel build.
175 Disable this to suppress the "warning: 'foo' is deprecated
176 (declared at kernel/power/somefile.c:1234)" messages.
178 config ENABLE_MUST_CHECK
179 bool "Enable __must_check logic"
182 Enable the __must_check logic in the kernel build. Disable this to
183 suppress the "warning: ignoring return value of 'foo', declared with
184 attribute warn_unused_result" messages.
187 int "Warn for stack frames larger than (needs gcc 4.4)"
189 default 1024 if !64BIT
190 default 2048 if 64BIT
192 Tell gcc to warn at build time for stack frames larger than this.
193 Setting this too low will cause a lot of warnings.
194 Setting it to 0 disables the warning.
197 config STRIP_ASM_SYMS
198 bool "Strip assembler-generated symbols during link"
201 Strip internal assembler-generated symbols during a link (symbols
202 that look like '.Lxxx') so they don't pollute the output of
203 get_wchan() and suchlike.
206 bool "Generate readable assembler code"
207 depends on DEBUG_KERNEL
209 Disable some compiler optimizations that tend to generate human unreadable
210 assembler output. This may make the kernel slightly slower, but it helps
211 to keep kernel developers who have to stare a lot at assembler listings
214 config UNUSED_SYMBOLS
215 bool "Enable unused/obsolete exported symbols"
218 Unused but exported symbols make the kernel needlessly bigger. For
219 that reason most of these unused exports will soon be removed. This
220 option is provided temporarily to provide a transition period in case
221 some external kernel module needs one of these symbols anyway. If you
222 encounter such a case in your module, consider if you are actually
223 using the right API. (rationale: since nobody in the kernel is using
224 this in a module, there is a pretty good chance it's actually the
225 wrong interface to use). If you really need the symbol, please send a
226 mail to the linux kernel mailing list mentioning the symbol and why
227 you really need it, and what the merge plan to the mainline kernel for
231 bool "Track page owner"
232 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
235 select PAGE_EXTENSION
237 This keeps track of what call chain is the owner of a page, may
238 help to find bare alloc_page(s) leaks. Even if you include this
239 feature on your build, it is disabled in default. You should pass
240 "page_owner=on" to boot parameter in order to enable it. Eats
241 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
242 for user-space helper.
247 bool "Debug Filesystem"
249 debugfs is a virtual file system that kernel developers use to put
250 debugging files into. Enable this option to be able to read and
251 write to these files.
253 For detailed documentation on the debugfs API, see
254 Documentation/DocBook/filesystems.
259 bool "Run 'make headers_check' when building vmlinux"
262 This option will extract the user-visible kernel headers whenever
263 building the kernel, and will run basic sanity checks on them to
264 ensure that exported files do not attempt to include files which
265 were not exported, etc.
267 If you're making modifications to header files which are
268 relevant for userspace, say 'Y', and check the headers
269 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
270 your build tree), to make sure they're suitable.
272 config DEBUG_SECTION_MISMATCH
273 bool "Enable full Section mismatch analysis"
275 The section mismatch analysis checks if there are illegal
276 references from one section to another section.
277 During linktime or runtime, some sections are dropped;
278 any use of code/data previously in these sections would
279 most likely result in an oops.
280 In the code, functions and variables are annotated with
281 __init,, etc. (see the full list in include/linux/init.h),
282 which results in the code/data being placed in specific sections.
283 The section mismatch analysis is always performed after a full
284 kernel build, and enabling this option causes the following
285 additional steps to occur:
286 - Add the option -fno-inline-functions-called-once to gcc commands.
287 When inlining a function annotated with __init in a non-init
288 function, we would lose the section information and thus
289 the analysis would not catch the illegal reference.
290 This option tells gcc to inline less (but it does result in
292 - Run the section mismatch analysis for each module/built-in.o file.
293 When we run the section mismatch analysis on vmlinux.o, we
294 lose valueble information about where the mismatch was
296 Running the analysis for each module/built-in.o file
297 tells where the mismatch happens much closer to the
298 source. The drawback is that the same mismatch is
299 reported at least twice.
300 - Enable verbose reporting from modpost in order to help resolve
301 the section mismatches that are reported.
304 # Select this config option from the architecture Kconfig, if it
305 # is preferred to always offer frame pointers as a config
306 # option on the architecture (regardless of KERNEL_DEBUG):
308 config ARCH_WANT_FRAME_POINTERS
313 bool "Compile the kernel with frame pointers"
314 depends on DEBUG_KERNEL && \
315 (CRIS || M68K || FRV || UML || \
316 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
317 ARCH_WANT_FRAME_POINTERS
318 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
320 If you say Y here the resulting kernel image will be slightly
321 larger and slower, but it gives very useful debugging information
322 in case of kernel bugs. (precise oopses/stacktraces/warnings)
324 config DEBUG_FORCE_WEAK_PER_CPU
325 bool "Force weak per-cpu definitions"
326 depends on DEBUG_KERNEL
328 s390 and alpha require percpu variables in modules to be
329 defined weak to work around addressing range issue which
330 puts the following two restrictions on percpu variable
333 1. percpu symbols must be unique whether static or not
334 2. percpu variables can't be defined inside a function
336 To ensure that generic code follows the above rules, this
337 option forces all percpu variables to be defined as weak.
339 endmenu # "Compiler options"
342 bool "Magic SysRq key"
345 If you say Y here, you will have some control over the system even
346 if the system crashes for example during kernel debugging (e.g., you
347 will be able to flush the buffer cache to disk, reboot the system
348 immediately or dump some status information). This is accomplished
349 by pressing various keys while holding SysRq (Alt+PrintScreen). It
350 also works on a serial console (on PC hardware at least), if you
351 send a BREAK and then within 5 seconds a command keypress. The
352 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
353 unless you really know what this hack does.
355 config MAGIC_SYSRQ_DEFAULT_ENABLE
356 hex "Enable magic SysRq key functions by default"
357 depends on MAGIC_SYSRQ
360 Specifies which SysRq key functions are enabled by default.
361 This may be set to 1 or 0 to enable or disable them all, or
362 to a bitmask as described in Documentation/sysrq.txt.
365 bool "Kernel debugging"
367 Say Y here if you are developing drivers or trying to debug and
368 identify kernel problems.
370 menu "Memory Debugging"
372 source mm/Kconfig.debug
375 bool "Debug object operations"
376 depends on DEBUG_KERNEL
378 If you say Y here, additional code will be inserted into the
379 kernel to track the life time of various objects and validate
380 the operations on those objects.
382 config DEBUG_OBJECTS_SELFTEST
383 bool "Debug objects selftest"
384 depends on DEBUG_OBJECTS
386 This enables the selftest of the object debug code.
388 config DEBUG_OBJECTS_FREE
389 bool "Debug objects in freed memory"
390 depends on DEBUG_OBJECTS
392 This enables checks whether a k/v free operation frees an area
393 which contains an object which has not been deactivated
394 properly. This can make kmalloc/kfree-intensive workloads
397 config DEBUG_OBJECTS_TIMERS
398 bool "Debug timer objects"
399 depends on DEBUG_OBJECTS
401 If you say Y here, additional code will be inserted into the
402 timer routines to track the life time of timer objects and
403 validate the timer operations.
405 config DEBUG_OBJECTS_WORK
406 bool "Debug work objects"
407 depends on DEBUG_OBJECTS
409 If you say Y here, additional code will be inserted into the
410 work queue routines to track the life time of work objects and
411 validate the work operations.
413 config DEBUG_OBJECTS_RCU_HEAD
414 bool "Debug RCU callbacks objects"
415 depends on DEBUG_OBJECTS
417 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
419 config DEBUG_OBJECTS_PERCPU_COUNTER
420 bool "Debug percpu counter objects"
421 depends on DEBUG_OBJECTS
423 If you say Y here, additional code will be inserted into the
424 percpu counter routines to track the life time of percpu counter
425 objects and validate the percpu counter operations.
427 config DEBUG_OBJECTS_ENABLE_DEFAULT
428 int "debug_objects bootup default value (0-1)"
431 depends on DEBUG_OBJECTS
433 Debug objects boot parameter default value
436 bool "Debug slab memory allocations"
437 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
439 Say Y here to have the kernel do limited verification on memory
440 allocation as well as poisoning memory on free to catch use of freed
441 memory. This can make kmalloc/kfree-intensive workloads much slower.
443 config DEBUG_SLAB_LEAK
444 bool "Memory leak debugging"
445 depends on DEBUG_SLAB
448 bool "SLUB debugging on by default"
449 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
452 Boot with debugging on by default. SLUB boots by default with
453 the runtime debug capabilities switched off. Enabling this is
454 equivalent to specifying the "slub_debug" parameter on boot.
455 There is no support for more fine grained debug control like
456 possible with slub_debug=xxx. SLUB debugging may be switched
457 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
462 bool "Enable SLUB performance statistics"
463 depends on SLUB && SYSFS
465 SLUB statistics are useful to debug SLUBs allocation behavior in
466 order find ways to optimize the allocator. This should never be
467 enabled for production use since keeping statistics slows down
468 the allocator by a few percentage points. The slabinfo command
469 supports the determination of the most active slabs to figure
470 out which slabs are relevant to a particular load.
471 Try running: slabinfo -DA
473 config HAVE_DEBUG_KMEMLEAK
476 config DEBUG_KMEMLEAK
477 bool "Kernel memory leak detector"
478 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
480 select STACKTRACE if STACKTRACE_SUPPORT
484 Say Y here if you want to enable the memory leak
485 detector. The memory allocation/freeing is traced in a way
486 similar to the Boehm's conservative garbage collector, the
487 difference being that the orphan objects are not freed but
488 only shown in /sys/kernel/debug/kmemleak. Enabling this
489 feature will introduce an overhead to memory
490 allocations. See Documentation/kmemleak.txt for more
493 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
494 of finding leaks due to the slab objects poisoning.
496 In order to access the kmemleak file, debugfs needs to be
497 mounted (usually at /sys/kernel/debug).
499 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
500 int "Maximum kmemleak early log entries"
501 depends on DEBUG_KMEMLEAK
505 Kmemleak must track all the memory allocations to avoid
506 reporting false positives. Since memory may be allocated or
507 freed before kmemleak is initialised, an early log buffer is
508 used to store these actions. If kmemleak reports "early log
509 buffer exceeded", please increase this value.
511 config DEBUG_KMEMLEAK_TEST
512 tristate "Simple test for the kernel memory leak detector"
513 depends on DEBUG_KMEMLEAK && m
515 This option enables a module that explicitly leaks memory.
519 config DEBUG_KMEMLEAK_DEFAULT_OFF
520 bool "Default kmemleak to off"
521 depends on DEBUG_KMEMLEAK
523 Say Y here to disable kmemleak by default. It can then be enabled
524 on the command line via kmemleak=on.
526 config DEBUG_STACK_USAGE
527 bool "Stack utilization instrumentation"
528 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
530 Enables the display of the minimum amount of free stack which each
531 task has ever had available in the sysrq-T and sysrq-P debug output.
533 This option will slow down process creation somewhat.
537 depends on DEBUG_KERNEL
539 Enable this to turn on extended checks in the virtual-memory system
540 that may impact performance.
544 config DEBUG_VM_VMACACHE
545 bool "Debug VMA caching"
548 Enable this to turn on VMA caching debug information. Doing so
549 can cause significant overhead, so only enable it in non-production
555 bool "Debug VM red-black trees"
558 Enable VM red-black tree debugging information and extra validations.
563 bool "Debug VM translations"
564 depends on DEBUG_KERNEL && X86
566 Enable some costly sanity checks in virtual to page code. This can
567 catch mistakes with virt_to_page() and friends.
571 config DEBUG_NOMMU_REGIONS
572 bool "Debug the global anon/private NOMMU mapping region tree"
573 depends on DEBUG_KERNEL && !MMU
575 This option causes the global tree of anonymous and private mapping
576 regions to be regularly checked for invalid topology.
578 config DEBUG_MEMORY_INIT
579 bool "Debug memory initialisation" if EXPERT
582 Enable this for additional checks during memory initialisation.
583 The sanity checks verify aspects of the VM such as the memory model
584 and other information provided by the architecture. Verbose
585 information will be printed at KERN_DEBUG loglevel depending
586 on the mminit_loglevel= command-line option.
590 config MEMORY_NOTIFIER_ERROR_INJECT
591 tristate "Memory hotplug notifier error injection module"
592 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
594 This option provides the ability to inject artificial errors to
595 memory hotplug notifier chain callbacks. It is controlled through
596 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
598 If the notifier call chain should be failed with some events
599 notified, write the error code to "actions/<notifier event>/error".
601 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
603 # cd /sys/kernel/debug/notifier-error-inject/memory
604 # echo -12 > actions/MEM_GOING_OFFLINE/error
605 # echo offline > /sys/devices/system/memory/memoryXXX/state
606 bash: echo: write error: Cannot allocate memory
608 To compile this code as a module, choose M here: the module will
609 be called memory-notifier-error-inject.
613 config DEBUG_PER_CPU_MAPS
614 bool "Debug access to per_cpu maps"
615 depends on DEBUG_KERNEL
618 Say Y to verify that the per_cpu map being accessed has
619 been set up. This adds a fair amount of code to kernel memory
620 and decreases performance.
625 bool "Highmem debugging"
626 depends on DEBUG_KERNEL && HIGHMEM
628 This option enables additional error checking for high memory
629 systems. Disable for production systems.
631 config HAVE_DEBUG_STACKOVERFLOW
634 config DEBUG_STACKOVERFLOW
635 bool "Check for stack overflows"
636 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
638 Say Y here if you want to check for overflows of kernel, IRQ
639 and exception stacks (if your architecture uses them). This
640 option will show detailed messages if free stack space drops
641 below a certain limit.
643 These kinds of bugs usually occur when call-chains in the
644 kernel get too deep, especially when interrupts are
647 Use this in cases where you see apparently random memory
648 corruption, especially if it appears in 'struct thread_info'
650 If in doubt, say "N".
652 source "lib/Kconfig.kmemcheck"
654 source "lib/Kconfig.kasan"
656 endmenu # "Memory Debugging"
659 bool "Debug shared IRQ handlers"
660 depends on DEBUG_KERNEL
662 Enable this to generate a spurious interrupt as soon as a shared
663 interrupt handler is registered, and just before one is deregistered.
664 Drivers ought to be able to handle interrupts coming in at those
665 points; some don't and need to be caught.
667 menu "Debug Lockups and Hangs"
669 config LOCKUP_DETECTOR
670 bool "Detect Hard and Soft Lockups"
671 depends on DEBUG_KERNEL && !S390
673 Say Y here to enable the kernel to act as a watchdog to detect
674 hard and soft lockups.
676 Softlockups are bugs that cause the kernel to loop in kernel
677 mode for more than 20 seconds, without giving other tasks a
678 chance to run. The current stack trace is displayed upon
679 detection and the system will stay locked up.
681 Hardlockups are bugs that cause the CPU to loop in kernel mode
682 for more than 10 seconds, without letting other interrupts have a
683 chance to run. The current stack trace is displayed upon detection
684 and the system will stay locked up.
686 The overhead should be minimal. A periodic hrtimer runs to
687 generate interrupts and kick the watchdog task every 4 seconds.
688 An NMI is generated every 10 seconds or so to check for hardlockups.
690 The frequency of hrtimer and NMI events and the soft and hard lockup
691 thresholds can be controlled through the sysctl watchdog_thresh.
693 config HARDLOCKUP_DETECTOR
695 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
696 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
698 config BOOTPARAM_HARDLOCKUP_PANIC
699 bool "Panic (Reboot) On Hard Lockups"
700 depends on HARDLOCKUP_DETECTOR
702 Say Y here to enable the kernel to panic on "hard lockups",
703 which are bugs that cause the kernel to loop in kernel
704 mode with interrupts disabled for more than 10 seconds (configurable
705 using the watchdog_thresh sysctl).
709 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
711 depends on HARDLOCKUP_DETECTOR
713 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
714 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
716 config BOOTPARAM_SOFTLOCKUP_PANIC
717 bool "Panic (Reboot) On Soft Lockups"
718 depends on LOCKUP_DETECTOR
720 Say Y here to enable the kernel to panic on "soft lockups",
721 which are bugs that cause the kernel to loop in kernel
722 mode for more than 20 seconds (configurable using the watchdog_thresh
723 sysctl), without giving other tasks a chance to run.
725 The panic can be used in combination with panic_timeout,
726 to cause the system to reboot automatically after a
727 lockup has been detected. This feature is useful for
728 high-availability systems that have uptime guarantees and
729 where a lockup must be resolved ASAP.
733 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
735 depends on LOCKUP_DETECTOR
737 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
738 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
740 config DETECT_HUNG_TASK
741 bool "Detect Hung Tasks"
742 depends on DEBUG_KERNEL
743 default LOCKUP_DETECTOR
745 Say Y here to enable the kernel to detect "hung tasks",
746 which are bugs that cause the task to be stuck in
747 uninterruptible "D" state indefinitiley.
749 When a hung task is detected, the kernel will print the
750 current stack trace (which you should report), but the
751 task will stay in uninterruptible state. If lockdep is
752 enabled then all held locks will also be reported. This
753 feature has negligible overhead.
755 config DEFAULT_HUNG_TASK_TIMEOUT
756 int "Default timeout for hung task detection (in seconds)"
757 depends on DETECT_HUNG_TASK
760 This option controls the default timeout (in seconds) used
761 to determine when a task has become non-responsive and should
764 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
765 sysctl or by writing a value to
766 /proc/sys/kernel/hung_task_timeout_secs.
768 A timeout of 0 disables the check. The default is two minutes.
769 Keeping the default should be fine in most cases.
771 config BOOTPARAM_HUNG_TASK_PANIC
772 bool "Panic (Reboot) On Hung Tasks"
773 depends on DETECT_HUNG_TASK
775 Say Y here to enable the kernel to panic on "hung tasks",
776 which are bugs that cause the kernel to leave a task stuck
777 in uninterruptible "D" state.
779 The panic can be used in combination with panic_timeout,
780 to cause the system to reboot automatically after a
781 hung task has been detected. This feature is useful for
782 high-availability systems that have uptime guarantees and
783 where a hung tasks must be resolved ASAP.
787 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
789 depends on DETECT_HUNG_TASK
791 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
792 default 1 if BOOTPARAM_HUNG_TASK_PANIC
794 endmenu # "Debug lockups and hangs"
799 Say Y here to enable the kernel to panic when it oopses. This
800 has the same effect as setting oops=panic on the kernel command
803 This feature is useful to ensure that the kernel does not do
804 anything erroneous after an oops which could result in data
805 corruption or other issues.
809 config PANIC_ON_OOPS_VALUE
812 default 0 if !PANIC_ON_OOPS
813 default 1 if PANIC_ON_OOPS
819 Set the timeout value (in seconds) until a reboot occurs when the
820 the kernel panics. If n = 0, then we wait forever. A timeout
821 value n > 0 will wait n seconds before rebooting, while a timeout
822 value n < 0 will reboot immediately.
825 bool "Collect scheduler debugging info"
826 depends on DEBUG_KERNEL && PROC_FS
829 If you say Y here, the /proc/sched_debug file will be provided
830 that can help debug the scheduler. The runtime overhead of this
834 bool "Collect scheduler statistics"
835 depends on DEBUG_KERNEL && PROC_FS
837 If you say Y here, additional code will be inserted into the
838 scheduler and related routines to collect statistics about
839 scheduler behavior and provide them in /proc/schedstat. These
840 stats may be useful for both tuning and debugging the scheduler
841 If you aren't debugging the scheduler or trying to tune a specific
842 application, you can say N to avoid the very slight overhead
845 config SCHED_STACK_END_CHECK
846 bool "Detect stack corruption on calls to schedule()"
847 depends on DEBUG_KERNEL
850 This option checks for a stack overrun on calls to schedule().
851 If the stack end location is found to be over written always panic as
852 the content of the corrupted region can no longer be trusted.
853 This is to ensure no erroneous behaviour occurs which could result in
854 data corruption or a sporadic crash at a later stage once the region
855 is examined. The runtime overhead introduced is minimal.
858 bool "Collect kernel timers statistics"
859 depends on DEBUG_KERNEL && PROC_FS
861 If you say Y here, additional code will be inserted into the
862 timer routines to collect statistics about kernel timers being
863 reprogrammed. The statistics can be read from /proc/timer_stats.
864 The statistics collection is started by writing 1 to /proc/timer_stats,
865 writing 0 stops it. This feature is useful to collect information
866 about timer usage patterns in kernel and userspace. This feature
867 is lightweight if enabled in the kernel config but not activated
868 (it defaults to deactivated on bootup and will only be activated
869 if some application like powertop activates it explicitly).
872 bool "Debug preemptible kernel"
873 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
876 If you say Y here then the kernel will use a debug variant of the
877 commonly used smp_processor_id() function and will print warnings
878 if kernel code uses it in a preemption-unsafe way. Also, the kernel
879 will detect preemption count underflows.
881 menu "Lock Debugging (spinlocks, mutexes, etc...)"
883 config DEBUG_RT_MUTEXES
884 bool "RT Mutex debugging, deadlock detection"
885 depends on DEBUG_KERNEL && RT_MUTEXES
887 This allows rt mutex semantics violations and rt mutex related
888 deadlocks (lockups) to be detected and reported automatically.
890 config RT_MUTEX_TESTER
891 bool "Built-in scriptable tester for rt-mutexes"
892 depends on DEBUG_KERNEL && RT_MUTEXES && BROKEN
894 This option enables a rt-mutex tester.
896 config DEBUG_SPINLOCK
897 bool "Spinlock and rw-lock debugging: basic checks"
898 depends on DEBUG_KERNEL
899 select UNINLINE_SPIN_UNLOCK
901 Say Y here and build SMP to catch missing spinlock initialization
902 and certain other kinds of spinlock errors commonly made. This is
903 best used in conjunction with the NMI watchdog so that spinlock
904 deadlocks are also debuggable.
907 bool "Mutex debugging: basic checks"
908 depends on DEBUG_KERNEL
910 This feature allows mutex semantics violations to be detected and
913 config DEBUG_WW_MUTEX_SLOWPATH
914 bool "Wait/wound mutex debugging: Slowpath testing"
915 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
916 select DEBUG_LOCK_ALLOC
917 select DEBUG_SPINLOCK
920 This feature enables slowpath testing for w/w mutex users by
921 injecting additional -EDEADLK wound/backoff cases. Together with
922 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
923 will test all possible w/w mutex interface abuse with the
924 exception of simply not acquiring all the required locks.
925 Note that this feature can introduce significant overhead, so
926 it really should not be enabled in a production or distro kernel,
927 even a debug kernel. If you are a driver writer, enable it. If
928 you are a distro, do not.
930 config DEBUG_LOCK_ALLOC
931 bool "Lock debugging: detect incorrect freeing of live locks"
932 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
933 select DEBUG_SPINLOCK
937 This feature will check whether any held lock (spinlock, rwlock,
938 mutex or rwsem) is incorrectly freed by the kernel, via any of the
939 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
940 vfree(), etc.), whether a live lock is incorrectly reinitialized via
941 spin_lock_init()/mutex_init()/etc., or whether there is any lock
942 held during task exit.
945 bool "Lock debugging: prove locking correctness"
946 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
948 select DEBUG_SPINLOCK
950 select DEBUG_LOCK_ALLOC
951 select TRACE_IRQFLAGS
954 This feature enables the kernel to prove that all locking
955 that occurs in the kernel runtime is mathematically
956 correct: that under no circumstance could an arbitrary (and
957 not yet triggered) combination of observed locking
958 sequences (on an arbitrary number of CPUs, running an
959 arbitrary number of tasks and interrupt contexts) cause a
962 In short, this feature enables the kernel to report locking
963 related deadlocks before they actually occur.
965 The proof does not depend on how hard and complex a
966 deadlock scenario would be to trigger: how many
967 participant CPUs, tasks and irq-contexts would be needed
968 for it to trigger. The proof also does not depend on
969 timing: if a race and a resulting deadlock is possible
970 theoretically (no matter how unlikely the race scenario
971 is), it will be proven so and will immediately be
972 reported by the kernel (once the event is observed that
973 makes the deadlock theoretically possible).
975 If a deadlock is impossible (i.e. the locking rules, as
976 observed by the kernel, are mathematically correct), the
977 kernel reports nothing.
979 NOTE: this feature can also be enabled for rwlocks, mutexes
980 and rwsems - in which case all dependencies between these
981 different locking variants are observed and mapped too, and
982 the proof of observed correctness is also maintained for an
983 arbitrary combination of these separate locking variants.
985 For more details, see Documentation/locking/lockdep-design.txt.
989 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
991 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
996 bool "Lock usage statistics"
997 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
999 select DEBUG_SPINLOCK
1000 select DEBUG_MUTEXES
1001 select DEBUG_LOCK_ALLOC
1004 This feature enables tracking lock contention points
1006 For more details, see Documentation/locking/lockstat.txt
1008 This also enables lock events required by "perf lock",
1010 If you want to use "perf lock", you also need to turn on
1011 CONFIG_EVENT_TRACING.
1013 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1014 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1016 config DEBUG_LOCKDEP
1017 bool "Lock dependency engine debugging"
1018 depends on DEBUG_KERNEL && LOCKDEP
1020 If you say Y here, the lock dependency engine will do
1021 additional runtime checks to debug itself, at the price
1022 of more runtime overhead.
1024 config DEBUG_ATOMIC_SLEEP
1025 bool "Sleep inside atomic section checking"
1026 select PREEMPT_COUNT
1027 depends on DEBUG_KERNEL
1029 If you say Y here, various routines which may sleep will become very
1030 noisy if they are called inside atomic sections: when a spinlock is
1031 held, inside an rcu read side critical section, inside preempt disabled
1032 sections, inside an interrupt, etc...
1034 config DEBUG_LOCKING_API_SELFTESTS
1035 bool "Locking API boot-time self-tests"
1036 depends on DEBUG_KERNEL
1038 Say Y here if you want the kernel to run a short self-test during
1039 bootup. The self-test checks whether common types of locking bugs
1040 are detected by debugging mechanisms or not. (if you disable
1041 lock debugging then those bugs wont be detected of course.)
1042 The following locking APIs are covered: spinlocks, rwlocks,
1045 config LOCK_TORTURE_TEST
1046 tristate "torture tests for locking"
1047 depends on DEBUG_KERNEL
1051 This option provides a kernel module that runs torture tests
1052 on kernel locking primitives. The kernel module may be built
1053 after the fact on the running kernel to be tested, if desired.
1055 Say Y here if you want kernel locking-primitive torture tests
1056 to be built into the kernel.
1057 Say M if you want these torture tests to build as a module.
1058 Say N if you are unsure.
1060 endmenu # lock debugging
1062 config TRACE_IRQFLAGS
1065 Enables hooks to interrupt enabling and disabling for
1066 either tracing or lock debugging.
1069 bool "Stack backtrace support"
1070 depends on STACKTRACE_SUPPORT
1072 This option causes the kernel to create a /proc/pid/stack for
1073 every process, showing its current stack trace.
1074 It is also used by various kernel debugging features that require
1075 stack trace generation.
1077 config DEBUG_KOBJECT
1078 bool "kobject debugging"
1079 depends on DEBUG_KERNEL
1081 If you say Y here, some extra kobject debugging messages will be sent
1084 config DEBUG_KOBJECT_RELEASE
1085 bool "kobject release debugging"
1086 depends on DEBUG_OBJECTS_TIMERS
1088 kobjects are reference counted objects. This means that their
1089 last reference count put is not predictable, and the kobject can
1090 live on past the point at which a driver decides to drop it's
1091 initial reference to the kobject gained on allocation. An
1092 example of this would be a struct device which has just been
1095 However, some buggy drivers assume that after such an operation,
1096 the memory backing the kobject can be immediately freed. This
1097 goes completely against the principles of a refcounted object.
1099 If you say Y here, the kernel will delay the release of kobjects
1100 on the last reference count to improve the visibility of this
1101 kind of kobject release bug.
1103 config HAVE_DEBUG_BUGVERBOSE
1106 config DEBUG_BUGVERBOSE
1107 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1108 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1111 Say Y here to make BUG() panics output the file name and line number
1112 of the BUG call as well as the EIP and oops trace. This aids
1113 debugging but costs about 70-100K of memory.
1116 bool "Debug linked list manipulation"
1117 depends on DEBUG_KERNEL
1119 Enable this to turn on extended checks in the linked-list
1124 config DEBUG_PI_LIST
1125 bool "Debug priority linked list manipulation"
1126 depends on DEBUG_KERNEL
1128 Enable this to turn on extended checks in the priority-ordered
1129 linked-list (plist) walking routines. This checks the entire
1130 list multiple times during each manipulation.
1135 bool "Debug SG table operations"
1136 depends on DEBUG_KERNEL
1138 Enable this to turn on checks on scatter-gather tables. This can
1139 help find problems with drivers that do not properly initialize
1144 config DEBUG_NOTIFIERS
1145 bool "Debug notifier call chains"
1146 depends on DEBUG_KERNEL
1148 Enable this to turn on sanity checking for notifier call chains.
1149 This is most useful for kernel developers to make sure that
1150 modules properly unregister themselves from notifier chains.
1151 This is a relatively cheap check but if you care about maximum
1154 config DEBUG_CREDENTIALS
1155 bool "Debug credential management"
1156 depends on DEBUG_KERNEL
1158 Enable this to turn on some debug checking for credential
1159 management. The additional code keeps track of the number of
1160 pointers from task_structs to any given cred struct, and checks to
1161 see that this number never exceeds the usage count of the cred
1164 Furthermore, if SELinux is enabled, this also checks that the
1165 security pointer in the cred struct is never seen to be invalid.
1169 menu "RCU Debugging"
1172 bool "RCU debugging: prove RCU correctness"
1173 depends on PROVE_LOCKING
1176 This feature enables lockdep extensions that check for correct
1177 use of RCU APIs. This is currently under development. Say Y
1178 if you want to debug RCU usage or help work on the PROVE_RCU
1181 Say N if you are unsure.
1183 config PROVE_RCU_REPEATEDLY
1184 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1185 depends on PROVE_RCU
1188 By itself, PROVE_RCU will disable checking upon issuing the
1189 first warning (or "splat"). This feature prevents such
1190 disabling, allowing multiple RCU-lockdep warnings to be printed
1193 Say Y to allow multiple RCU-lockdep warnings per boot.
1195 Say N if you are unsure.
1197 config SPARSE_RCU_POINTER
1198 bool "RCU debugging: sparse-based checks for pointer usage"
1201 This feature enables the __rcu sparse annotation for
1202 RCU-protected pointers. This annotation will cause sparse
1203 to flag any non-RCU used of annotated pointers. This can be
1204 helpful when debugging RCU usage. Please note that this feature
1205 is not intended to enforce code cleanliness; it is instead merely
1208 Say Y to make sparse flag questionable use of RCU-protected pointers
1210 Say N if you are unsure.
1216 config RCU_TORTURE_TEST
1217 tristate "torture tests for RCU"
1218 depends on DEBUG_KERNEL
1223 This option provides a kernel module that runs torture tests
1224 on the RCU infrastructure. The kernel module may be built
1225 after the fact on the running kernel to be tested, if desired.
1227 Say Y here if you want RCU torture tests to be built into
1229 Say M if you want the RCU torture tests to build as a module.
1230 Say N if you are unsure.
1232 config RCU_TORTURE_TEST_RUNNABLE
1233 bool "torture tests for RCU runnable by default"
1234 depends on RCU_TORTURE_TEST = y
1237 This option provides a way to build the RCU torture tests
1238 directly into the kernel without them starting up at boot
1239 time. You can use /proc/sys/kernel/rcutorture_runnable
1240 to manually override this setting. This /proc file is
1241 available only when the RCU torture tests have been built
1244 Say Y here if you want the RCU torture tests to start during
1245 boot (you probably don't).
1246 Say N here if you want the RCU torture tests to start only
1247 after being manually enabled via /proc.
1249 config RCU_CPU_STALL_TIMEOUT
1250 int "RCU CPU stall timeout in seconds"
1251 depends on RCU_STALL_COMMON
1255 If a given RCU grace period extends more than the specified
1256 number of seconds, a CPU stall warning is printed. If the
1257 RCU grace period persists, additional CPU stall warnings are
1258 printed at more widely spaced intervals.
1260 config RCU_CPU_STALL_INFO
1261 bool "Print additional diagnostics on RCU CPU stall"
1262 depends on (TREE_RCU || PREEMPT_RCU) && DEBUG_KERNEL
1265 For each stalled CPU that is aware of the current RCU grace
1266 period, print out additional per-CPU diagnostic information
1267 regarding scheduling-clock ticks, idle state, and,
1268 for RCU_FAST_NO_HZ kernels, idle-entry state.
1270 Say N if you are unsure.
1272 Say Y if you want to enable such diagnostics.
1275 bool "Enable tracing for RCU"
1276 depends on DEBUG_KERNEL
1279 This option provides tracing in RCU which presents stats
1280 in debugfs for debugging RCU implementation.
1282 Say Y here if you want to enable RCU tracing
1283 Say N if you are unsure.
1285 endmenu # "RCU Debugging"
1287 config DEBUG_BLOCK_EXT_DEVT
1288 bool "Force extended block device numbers and spread them"
1289 depends on DEBUG_KERNEL
1293 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1294 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1295 YOU ARE DOING. Distros, please enable this and fix whatever
1298 Conventionally, block device numbers are allocated from
1299 predetermined contiguous area. However, extended block area
1300 may introduce non-contiguous block device numbers. This
1301 option forces most block device numbers to be allocated from
1302 the extended space and spreads them to discover kernel or
1303 userland code paths which assume predetermined contiguous
1304 device number allocation.
1306 Note that turning on this debug option shuffles all the
1307 device numbers for all IDE and SCSI devices including libata
1308 ones, so root partition specified using device number
1309 directly (via rdev or root=MAJ:MIN) won't work anymore.
1310 Textual device names (root=/dev/sdXn) will continue to work.
1312 Say N if you are unsure.
1314 config NOTIFIER_ERROR_INJECTION
1315 tristate "Notifier error injection"
1316 depends on DEBUG_KERNEL
1319 This option provides the ability to inject artificial errors to
1320 specified notifier chain callbacks. It is useful to test the error
1321 handling of notifier call chain failures.
1325 config CPU_NOTIFIER_ERROR_INJECT
1326 tristate "CPU notifier error injection module"
1327 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1329 This option provides a kernel module that can be used to test
1330 the error handling of the cpu notifiers by injecting artificial
1331 errors to CPU notifier chain callbacks. It is controlled through
1332 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1334 If the notifier call chain should be failed with some events
1335 notified, write the error code to "actions/<notifier event>/error".
1337 Example: Inject CPU offline error (-1 == -EPERM)
1339 # cd /sys/kernel/debug/notifier-error-inject/cpu
1340 # echo -1 > actions/CPU_DOWN_PREPARE/error
1341 # echo 0 > /sys/devices/system/cpu/cpu1/online
1342 bash: echo: write error: Operation not permitted
1344 To compile this code as a module, choose M here: the module will
1345 be called cpu-notifier-error-inject.
1349 config PM_NOTIFIER_ERROR_INJECT
1350 tristate "PM notifier error injection module"
1351 depends on PM && NOTIFIER_ERROR_INJECTION
1352 default m if PM_DEBUG
1354 This option provides the ability to inject artificial errors to
1355 PM notifier chain callbacks. It is controlled through debugfs
1356 interface /sys/kernel/debug/notifier-error-inject/pm
1358 If the notifier call chain should be failed with some events
1359 notified, write the error code to "actions/<notifier event>/error".
1361 Example: Inject PM suspend error (-12 = -ENOMEM)
1363 # cd /sys/kernel/debug/notifier-error-inject/pm/
1364 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1365 # echo mem > /sys/power/state
1366 bash: echo: write error: Cannot allocate memory
1368 To compile this code as a module, choose M here: the module will
1369 be called pm-notifier-error-inject.
1373 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1374 tristate "OF reconfig notifier error injection module"
1375 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1377 This option provides the ability to inject artificial errors to
1378 OF reconfig notifier chain callbacks. It is controlled
1379 through debugfs interface under
1380 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1382 If the notifier call chain should be failed with some events
1383 notified, write the error code to "actions/<notifier event>/error".
1385 To compile this code as a module, choose M here: the module will
1386 be called of-reconfig-notifier-error-inject.
1390 config FAULT_INJECTION
1391 bool "Fault-injection framework"
1392 depends on DEBUG_KERNEL
1394 Provide fault-injection framework.
1395 For more details, see Documentation/fault-injection/.
1398 bool "Fault-injection capability for kmalloc"
1399 depends on FAULT_INJECTION
1400 depends on SLAB || SLUB
1402 Provide fault-injection capability for kmalloc.
1404 config FAIL_PAGE_ALLOC
1405 bool "Fault-injection capabilitiy for alloc_pages()"
1406 depends on FAULT_INJECTION
1408 Provide fault-injection capability for alloc_pages().
1410 config FAIL_MAKE_REQUEST
1411 bool "Fault-injection capability for disk IO"
1412 depends on FAULT_INJECTION && BLOCK
1414 Provide fault-injection capability for disk IO.
1416 config FAIL_IO_TIMEOUT
1417 bool "Fault-injection capability for faking disk interrupts"
1418 depends on FAULT_INJECTION && BLOCK
1420 Provide fault-injection capability on end IO handling. This
1421 will make the block layer "forget" an interrupt as configured,
1422 thus exercising the error handling.
1424 Only works with drivers that use the generic timeout handling,
1425 for others it wont do anything.
1427 config FAIL_MMC_REQUEST
1428 bool "Fault-injection capability for MMC IO"
1430 depends on FAULT_INJECTION && MMC
1432 Provide fault-injection capability for MMC IO.
1433 This will make the mmc core return data errors. This is
1434 useful to test the error handling in the mmc block device
1435 and to test how the mmc host driver handles retries from
1438 config FAULT_INJECTION_DEBUG_FS
1439 bool "Debugfs entries for fault-injection capabilities"
1440 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1442 Enable configuration of fault-injection capabilities via debugfs.
1444 config FAULT_INJECTION_STACKTRACE_FILTER
1445 bool "stacktrace filter for fault-injection capabilities"
1446 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1449 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1451 Provide stacktrace filter for fault-injection capabilities
1454 bool "Latency measuring infrastructure"
1455 depends on HAVE_LATENCYTOP_SUPPORT
1456 depends on DEBUG_KERNEL
1457 depends on STACKTRACE_SUPPORT
1459 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1466 Enable this option if you want to use the LatencyTOP tool
1467 to find out which userspace is blocking on what kernel operations.
1469 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1472 config DEBUG_STRICT_USER_COPY_CHECKS
1473 bool "Strict user copy size checks"
1474 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1475 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1477 Enabling this option turns a certain set of sanity checks for user
1478 copy operations into compile time failures.
1480 The copy_from_user() etc checks are there to help test if there
1481 are sufficient security checks on the length argument of
1482 the copy operation, by having gcc prove that the argument is
1487 source kernel/trace/Kconfig
1489 menu "Runtime Testing"
1492 tristate "Linux Kernel Dump Test Tool Module"
1497 This module enables testing of the different dumping mechanisms by
1498 inducing system failures at predefined crash points.
1499 If you don't need it: say N
1500 Choose M here to compile this code as a module. The module will be
1503 Documentation on how to use the module can be found in
1504 Documentation/fault-injection/provoke-crashes.txt
1506 config TEST_LIST_SORT
1507 bool "Linked list sorting test"
1508 depends on DEBUG_KERNEL
1510 Enable this to turn on 'list_sort()' function test. This test is
1511 executed only once during system boot, so affects only boot time.
1515 config KPROBES_SANITY_TEST
1516 bool "Kprobes sanity tests"
1517 depends on DEBUG_KERNEL
1521 This option provides for testing basic kprobes functionality on
1522 boot. A sample kprobe, jprobe and kretprobe are inserted and
1523 verified for functionality.
1525 Say N if you are unsure.
1527 config BACKTRACE_SELF_TEST
1528 tristate "Self test for the backtrace code"
1529 depends on DEBUG_KERNEL
1532 This option provides a kernel module that can be used to test
1533 the kernel stack backtrace code. This option is not useful
1534 for distributions or general kernels, but only for kernel
1535 developers working on architecture code.
1537 Note that if you want to also test saved backtraces, you will
1538 have to enable STACKTRACE as well.
1540 Say N if you are unsure.
1543 tristate "Red-Black tree test"
1544 depends on DEBUG_KERNEL
1546 A benchmark measuring the performance of the rbtree library.
1547 Also includes rbtree invariant checks.
1549 config INTERVAL_TREE_TEST
1550 tristate "Interval tree test"
1551 depends on m && DEBUG_KERNEL
1552 select INTERVAL_TREE
1554 A benchmark measuring the performance of the interval tree library
1557 tristate "Per cpu operations test"
1558 depends on m && DEBUG_KERNEL
1560 Enable this option to build test module which validates per-cpu
1565 config ATOMIC64_SELFTEST
1566 bool "Perform an atomic64_t self-test at boot"
1568 Enable this option to test the atomic64_t functions at boot.
1572 config ASYNC_RAID6_TEST
1573 tristate "Self test for hardware accelerated raid6 recovery"
1574 depends on ASYNC_RAID6_RECOV
1577 This is a one-shot self test that permutes through the
1578 recovery of all the possible two disk failure scenarios for a
1579 N-disk array. Recovery is performed with the asynchronous
1580 raid6 recovery routines, and will optionally use an offload
1581 engine if one is available.
1586 tristate "Test functions located in the hexdump module at runtime"
1588 config TEST_STRING_HELPERS
1589 tristate "Test functions located in the string_helpers module at runtime"
1592 tristate "Test kstrto*() family of functions at runtime"
1594 config TEST_RHASHTABLE
1595 tristate "Perform selftest on resizable hash table"
1598 Enable this option to test the rhashtable functions at boot.
1602 endmenu # runtime tests
1604 config PROVIDE_OHCI1394_DMA_INIT
1605 bool "Remote debugging over FireWire early on boot"
1606 depends on PCI && X86
1608 If you want to debug problems which hang or crash the kernel early
1609 on boot and the crashing machine has a FireWire port, you can use
1610 this feature to remotely access the memory of the crashed machine
1611 over FireWire. This employs remote DMA as part of the OHCI1394
1612 specification which is now the standard for FireWire controllers.
1614 With remote DMA, you can monitor the printk buffer remotely using
1615 firescope and access all memory below 4GB using fireproxy from gdb.
1616 Even controlling a kernel debugger is possible using remote DMA.
1620 If ohci1394_dma=early is used as boot parameter, it will initialize
1621 all OHCI1394 controllers which are found in the PCI config space.
1623 As all changes to the FireWire bus such as enabling and disabling
1624 devices cause a bus reset and thereby disable remote DMA for all
1625 devices, be sure to have the cable plugged and FireWire enabled on
1626 the debugging host before booting the debug target for debugging.
1628 This code (~1k) is freed after boot. By then, the firewire stack
1629 in charge of the OHCI-1394 controllers should be used instead.
1631 See Documentation/debugging-via-ohci1394.txt for more information.
1634 bool "Build targets in Documentation/ tree"
1635 depends on HEADERS_CHECK
1637 This option attempts to build objects from the source files in the
1638 kernel Documentation/ tree.
1640 Say N if you are unsure.
1642 config DMA_API_DEBUG
1643 bool "Enable debugging of DMA-API usage"
1644 depends on HAVE_DMA_API_DEBUG
1646 Enable this option to debug the use of the DMA API by device drivers.
1647 With this option you will be able to detect common bugs in device
1648 drivers like double-freeing of DMA mappings or freeing mappings that
1649 were never allocated.
1651 This also attempts to catch cases where a page owned by DMA is
1652 accessed by the cpu in a way that could cause data corruption. For
1653 example, this enables cow_user_page() to check that the source page is
1656 This option causes a performance degradation. Use only if you want to
1657 debug device drivers and dma interactions.
1662 tristate "Test module loading with 'hello world' module"
1666 This builds the "test_module" module that emits "Hello, world"
1667 on printk when loaded. It is designed to be used for basic
1668 evaluation of the module loading subsystem (for example when
1669 validating module verification). It lacks any extra dependencies,
1670 and will not normally be loaded by the system unless explicitly
1675 config TEST_USER_COPY
1676 tristate "Test user/kernel boundary protections"
1680 This builds the "test_user_copy" module that runs sanity checks
1681 on the copy_to/from_user infrastructure, making sure basic
1682 user/kernel boundary testing is working. If it fails to load,
1683 a regression has been detected in the user/kernel memory boundary
1689 tristate "Test BPF filter functionality"
1693 This builds the "test_bpf" module that runs various test vectors
1694 against the BPF interpreter or BPF JIT compiler depending on the
1695 current setting. This is in particular useful for BPF JIT compiler
1696 development, but also to run regression tests against changes in
1697 the interpreter code. It also enables test stubs for eBPF maps and
1698 verifier used by user space verifier testsuite.
1702 config TEST_FIRMWARE
1703 tristate "Test firmware loading via userspace interface"
1705 depends on FW_LOADER
1707 This builds the "test_firmware" module that creates a userspace
1708 interface for testing firmware loading. This can be used to
1709 control the triggering of firmware loading without needing an
1710 actual firmware-using device. The contents can be rechecked by
1716 tristate "udelay test driver"
1719 This builds the "udelay_test" module that helps to make sure
1720 that udelay() is working properly.
1724 source "samples/Kconfig"
1726 source "lib/Kconfig.kgdb"