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_STACK_USAGE
548 bool "Stack utilization instrumentation"
549 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
551 Enables the display of the minimum amount of free stack which each
552 task has ever had available in the sysrq-T and sysrq-P debug output.
554 This option will slow down process creation somewhat.
558 depends on DEBUG_KERNEL
560 Enable this to turn on extended checks in the virtual-memory system
561 that may impact performance.
565 config DEBUG_VM_VMACACHE
566 bool "Debug VMA caching"
569 Enable this to turn on VMA caching debug information. Doing so
570 can cause significant overhead, so only enable it in non-production
576 bool "Debug VM red-black trees"
579 Enable VM red-black tree debugging information and extra validations.
584 bool "Debug VM translations"
585 depends on DEBUG_KERNEL && X86
587 Enable some costly sanity checks in virtual to page code. This can
588 catch mistakes with virt_to_page() and friends.
592 config DEBUG_NOMMU_REGIONS
593 bool "Debug the global anon/private NOMMU mapping region tree"
594 depends on DEBUG_KERNEL && !MMU
596 This option causes the global tree of anonymous and private mapping
597 regions to be regularly checked for invalid topology.
599 config DEBUG_MEMORY_INIT
600 bool "Debug memory initialisation" if EXPERT
603 Enable this for additional checks during memory initialisation.
604 The sanity checks verify aspects of the VM such as the memory model
605 and other information provided by the architecture. Verbose
606 information will be printed at KERN_DEBUG loglevel depending
607 on the mminit_loglevel= command-line option.
611 config MEMORY_NOTIFIER_ERROR_INJECT
612 tristate "Memory hotplug notifier error injection module"
613 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
615 This option provides the ability to inject artificial errors to
616 memory hotplug notifier chain callbacks. It is controlled through
617 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
619 If the notifier call chain should be failed with some events
620 notified, write the error code to "actions/<notifier event>/error".
622 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
624 # cd /sys/kernel/debug/notifier-error-inject/memory
625 # echo -12 > actions/MEM_GOING_OFFLINE/error
626 # echo offline > /sys/devices/system/memory/memoryXXX/state
627 bash: echo: write error: Cannot allocate memory
629 To compile this code as a module, choose M here: the module will
630 be called memory-notifier-error-inject.
634 config DEBUG_PER_CPU_MAPS
635 bool "Debug access to per_cpu maps"
636 depends on DEBUG_KERNEL
639 Say Y to verify that the per_cpu map being accessed has
640 been set up. This adds a fair amount of code to kernel memory
641 and decreases performance.
646 bool "Highmem debugging"
647 depends on DEBUG_KERNEL && HIGHMEM
649 This option enables additional error checking for high memory
650 systems. Disable for production systems.
652 config HAVE_DEBUG_STACKOVERFLOW
655 config DEBUG_STACKOVERFLOW
656 bool "Check for stack overflows"
657 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
659 Say Y here if you want to check for overflows of kernel, IRQ
660 and exception stacks (if your architecture uses them). This
661 option will show detailed messages if free stack space drops
662 below a certain limit.
664 These kinds of bugs usually occur when call-chains in the
665 kernel get too deep, especially when interrupts are
668 Use this in cases where you see apparently random memory
669 corruption, especially if it appears in 'struct thread_info'
671 If in doubt, say "N".
673 source "lib/Kconfig.kmemcheck"
675 source "lib/Kconfig.kasan"
677 endmenu # "Memory Debugging"
680 bool "Debug shared IRQ handlers"
681 depends on DEBUG_KERNEL
683 Enable this to generate a spurious interrupt as soon as a shared
684 interrupt handler is registered, and just before one is deregistered.
685 Drivers ought to be able to handle interrupts coming in at those
686 points; some don't and need to be caught.
688 menu "Debug Lockups and Hangs"
690 config LOCKUP_DETECTOR
691 bool "Detect Hard and Soft Lockups"
692 depends on DEBUG_KERNEL && !S390
694 Say Y here to enable the kernel to act as a watchdog to detect
695 hard and soft lockups.
697 Softlockups are bugs that cause the kernel to loop in kernel
698 mode for more than 20 seconds, without giving other tasks a
699 chance to run. The current stack trace is displayed upon
700 detection and the system will stay locked up.
702 Hardlockups are bugs that cause the CPU to loop in kernel mode
703 for more than 10 seconds, without letting other interrupts have a
704 chance to run. The current stack trace is displayed upon detection
705 and the system will stay locked up.
707 The overhead should be minimal. A periodic hrtimer runs to
708 generate interrupts and kick the watchdog task every 4 seconds.
709 An NMI is generated every 10 seconds or so to check for hardlockups.
711 The frequency of hrtimer and NMI events and the soft and hard lockup
712 thresholds can be controlled through the sysctl watchdog_thresh.
714 config HARDLOCKUP_DETECTOR
716 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
717 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
719 config BOOTPARAM_HARDLOCKUP_PANIC
720 bool "Panic (Reboot) On Hard Lockups"
721 depends on HARDLOCKUP_DETECTOR
723 Say Y here to enable the kernel to panic on "hard lockups",
724 which are bugs that cause the kernel to loop in kernel
725 mode with interrupts disabled for more than 10 seconds (configurable
726 using the watchdog_thresh sysctl).
730 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
732 depends on HARDLOCKUP_DETECTOR
734 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
735 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
737 config BOOTPARAM_SOFTLOCKUP_PANIC
738 bool "Panic (Reboot) On Soft Lockups"
739 depends on LOCKUP_DETECTOR
741 Say Y here to enable the kernel to panic on "soft lockups",
742 which are bugs that cause the kernel to loop in kernel
743 mode for more than 20 seconds (configurable using the watchdog_thresh
744 sysctl), without giving other tasks a chance to run.
746 The panic can be used in combination with panic_timeout,
747 to cause the system to reboot automatically after a
748 lockup has been detected. This feature is useful for
749 high-availability systems that have uptime guarantees and
750 where a lockup must be resolved ASAP.
754 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
756 depends on LOCKUP_DETECTOR
758 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
759 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
761 config DETECT_HUNG_TASK
762 bool "Detect Hung Tasks"
763 depends on DEBUG_KERNEL
764 default LOCKUP_DETECTOR
766 Say Y here to enable the kernel to detect "hung tasks",
767 which are bugs that cause the task to be stuck in
768 uninterruptible "D" state indefinitiley.
770 When a hung task is detected, the kernel will print the
771 current stack trace (which you should report), but the
772 task will stay in uninterruptible state. If lockdep is
773 enabled then all held locks will also be reported. This
774 feature has negligible overhead.
776 config DEFAULT_HUNG_TASK_TIMEOUT
777 int "Default timeout for hung task detection (in seconds)"
778 depends on DETECT_HUNG_TASK
781 This option controls the default timeout (in seconds) used
782 to determine when a task has become non-responsive and should
785 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
786 sysctl or by writing a value to
787 /proc/sys/kernel/hung_task_timeout_secs.
789 A timeout of 0 disables the check. The default is two minutes.
790 Keeping the default should be fine in most cases.
792 config BOOTPARAM_HUNG_TASK_PANIC
793 bool "Panic (Reboot) On Hung Tasks"
794 depends on DETECT_HUNG_TASK
796 Say Y here to enable the kernel to panic on "hung tasks",
797 which are bugs that cause the kernel to leave a task stuck
798 in uninterruptible "D" state.
800 The panic can be used in combination with panic_timeout,
801 to cause the system to reboot automatically after a
802 hung task has been detected. This feature is useful for
803 high-availability systems that have uptime guarantees and
804 where a hung tasks must be resolved ASAP.
808 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
810 depends on DETECT_HUNG_TASK
812 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
813 default 1 if BOOTPARAM_HUNG_TASK_PANIC
816 bool "Detect Workqueue Stalls"
817 depends on DEBUG_KERNEL
819 Say Y here to enable stall detection on workqueues. If a
820 worker pool doesn't make forward progress on a pending work
821 item for over a given amount of time, 30s by default, a
822 warning message is printed along with dump of workqueue
823 state. This can be configured through kernel parameter
824 "workqueue.watchdog_thresh" and its sysfs counterpart.
826 endmenu # "Debug lockups and hangs"
831 Say Y here to enable the kernel to panic when it oopses. This
832 has the same effect as setting oops=panic on the kernel command
835 This feature is useful to ensure that the kernel does not do
836 anything erroneous after an oops which could result in data
837 corruption or other issues.
841 config PANIC_ON_OOPS_VALUE
844 default 0 if !PANIC_ON_OOPS
845 default 1 if PANIC_ON_OOPS
851 Set the timeout value (in seconds) until a reboot occurs when the
852 the kernel panics. If n = 0, then we wait forever. A timeout
853 value n > 0 will wait n seconds before rebooting, while a timeout
854 value n < 0 will reboot immediately.
857 bool "Collect scheduler debugging info"
858 depends on DEBUG_KERNEL && PROC_FS
861 If you say Y here, the /proc/sched_debug file will be provided
862 that can help debug the scheduler. The runtime overhead of this
870 bool "Collect scheduler statistics"
871 depends on DEBUG_KERNEL && PROC_FS
874 If you say Y here, additional code will be inserted into the
875 scheduler and related routines to collect statistics about
876 scheduler behavior and provide them in /proc/schedstat. These
877 stats may be useful for both tuning and debugging the scheduler
878 If you aren't debugging the scheduler or trying to tune a specific
879 application, you can say N to avoid the very slight overhead
882 config SCHED_STACK_END_CHECK
883 bool "Detect stack corruption on calls to schedule()"
884 depends on DEBUG_KERNEL
887 This option checks for a stack overrun on calls to schedule().
888 If the stack end location is found to be over written always panic as
889 the content of the corrupted region can no longer be trusted.
890 This is to ensure no erroneous behaviour occurs which could result in
891 data corruption or a sporadic crash at a later stage once the region
892 is examined. The runtime overhead introduced is minimal.
894 config DEBUG_TIMEKEEPING
895 bool "Enable extra timekeeping sanity checking"
897 This option will enable additional timekeeping sanity checks
898 which may be helpful when diagnosing issues where timekeeping
899 problems are suspected.
901 This may include checks in the timekeeping hotpaths, so this
902 option may have a (very small) performance impact to some
908 bool "Collect kernel timers statistics"
909 depends on DEBUG_KERNEL && PROC_FS
911 If you say Y here, additional code will be inserted into the
912 timer routines to collect statistics about kernel timers being
913 reprogrammed. The statistics can be read from /proc/timer_stats.
914 The statistics collection is started by writing 1 to /proc/timer_stats,
915 writing 0 stops it. This feature is useful to collect information
916 about timer usage patterns in kernel and userspace. This feature
917 is lightweight if enabled in the kernel config but not activated
918 (it defaults to deactivated on bootup and will only be activated
919 if some application like powertop activates it explicitly).
922 bool "Debug preemptible kernel"
923 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
926 If you say Y here then the kernel will use a debug variant of the
927 commonly used smp_processor_id() function and will print warnings
928 if kernel code uses it in a preemption-unsafe way. Also, the kernel
929 will detect preemption count underflows.
931 menu "Lock Debugging (spinlocks, mutexes, etc...)"
933 config DEBUG_RT_MUTEXES
934 bool "RT Mutex debugging, deadlock detection"
935 depends on DEBUG_KERNEL && RT_MUTEXES
937 This allows rt mutex semantics violations and rt mutex related
938 deadlocks (lockups) to be detected and reported automatically.
940 config DEBUG_SPINLOCK
941 bool "Spinlock and rw-lock debugging: basic checks"
942 depends on DEBUG_KERNEL
943 select UNINLINE_SPIN_UNLOCK
945 Say Y here and build SMP to catch missing spinlock initialization
946 and certain other kinds of spinlock errors commonly made. This is
947 best used in conjunction with the NMI watchdog so that spinlock
948 deadlocks are also debuggable.
951 bool "Mutex debugging: basic checks"
952 depends on DEBUG_KERNEL
954 This feature allows mutex semantics violations to be detected and
957 config DEBUG_WW_MUTEX_SLOWPATH
958 bool "Wait/wound mutex debugging: Slowpath testing"
959 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
960 select DEBUG_LOCK_ALLOC
961 select DEBUG_SPINLOCK
964 This feature enables slowpath testing for w/w mutex users by
965 injecting additional -EDEADLK wound/backoff cases. Together with
966 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
967 will test all possible w/w mutex interface abuse with the
968 exception of simply not acquiring all the required locks.
969 Note that this feature can introduce significant overhead, so
970 it really should not be enabled in a production or distro kernel,
971 even a debug kernel. If you are a driver writer, enable it. If
972 you are a distro, do not.
974 config DEBUG_LOCK_ALLOC
975 bool "Lock debugging: detect incorrect freeing of live locks"
976 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
977 select DEBUG_SPINLOCK
981 This feature will check whether any held lock (spinlock, rwlock,
982 mutex or rwsem) is incorrectly freed by the kernel, via any of the
983 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
984 vfree(), etc.), whether a live lock is incorrectly reinitialized via
985 spin_lock_init()/mutex_init()/etc., or whether there is any lock
986 held during task exit.
989 bool "Lock debugging: prove locking correctness"
990 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
992 select DEBUG_SPINLOCK
994 select DEBUG_LOCK_ALLOC
995 select TRACE_IRQFLAGS
998 This feature enables the kernel to prove that all locking
999 that occurs in the kernel runtime is mathematically
1000 correct: that under no circumstance could an arbitrary (and
1001 not yet triggered) combination of observed locking
1002 sequences (on an arbitrary number of CPUs, running an
1003 arbitrary number of tasks and interrupt contexts) cause a
1006 In short, this feature enables the kernel to report locking
1007 related deadlocks before they actually occur.
1009 The proof does not depend on how hard and complex a
1010 deadlock scenario would be to trigger: how many
1011 participant CPUs, tasks and irq-contexts would be needed
1012 for it to trigger. The proof also does not depend on
1013 timing: if a race and a resulting deadlock is possible
1014 theoretically (no matter how unlikely the race scenario
1015 is), it will be proven so and will immediately be
1016 reported by the kernel (once the event is observed that
1017 makes the deadlock theoretically possible).
1019 If a deadlock is impossible (i.e. the locking rules, as
1020 observed by the kernel, are mathematically correct), the
1021 kernel reports nothing.
1023 NOTE: this feature can also be enabled for rwlocks, mutexes
1024 and rwsems - in which case all dependencies between these
1025 different locking variants are observed and mapped too, and
1026 the proof of observed correctness is also maintained for an
1027 arbitrary combination of these separate locking variants.
1029 For more details, see Documentation/locking/lockdep-design.txt.
1033 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1035 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
1040 bool "Lock usage statistics"
1041 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1043 select DEBUG_SPINLOCK
1044 select DEBUG_MUTEXES
1045 select DEBUG_LOCK_ALLOC
1048 This feature enables tracking lock contention points
1050 For more details, see Documentation/locking/lockstat.txt
1052 This also enables lock events required by "perf lock",
1054 If you want to use "perf lock", you also need to turn on
1055 CONFIG_EVENT_TRACING.
1057 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1058 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1060 config DEBUG_LOCKDEP
1061 bool "Lock dependency engine debugging"
1062 depends on DEBUG_KERNEL && LOCKDEP
1064 If you say Y here, the lock dependency engine will do
1065 additional runtime checks to debug itself, at the price
1066 of more runtime overhead.
1068 config DEBUG_ATOMIC_SLEEP
1069 bool "Sleep inside atomic section checking"
1070 select PREEMPT_COUNT
1071 depends on DEBUG_KERNEL
1073 If you say Y here, various routines which may sleep will become very
1074 noisy if they are called inside atomic sections: when a spinlock is
1075 held, inside an rcu read side critical section, inside preempt disabled
1076 sections, inside an interrupt, etc...
1078 config DEBUG_LOCKING_API_SELFTESTS
1079 bool "Locking API boot-time self-tests"
1080 depends on DEBUG_KERNEL
1082 Say Y here if you want the kernel to run a short self-test during
1083 bootup. The self-test checks whether common types of locking bugs
1084 are detected by debugging mechanisms or not. (if you disable
1085 lock debugging then those bugs wont be detected of course.)
1086 The following locking APIs are covered: spinlocks, rwlocks,
1089 config LOCK_TORTURE_TEST
1090 tristate "torture tests for locking"
1091 depends on DEBUG_KERNEL
1095 This option provides a kernel module that runs torture tests
1096 on kernel locking primitives. The kernel module may be built
1097 after the fact on the running kernel to be tested, if desired.
1099 Say Y here if you want kernel locking-primitive torture tests
1100 to be built into the kernel.
1101 Say M if you want these torture tests to build as a module.
1102 Say N if you are unsure.
1104 endmenu # lock debugging
1106 config TRACE_IRQFLAGS
1109 Enables hooks to interrupt enabling and disabling for
1110 either tracing or lock debugging.
1113 bool "Stack backtrace support"
1114 depends on STACKTRACE_SUPPORT
1116 This option causes the kernel to create a /proc/pid/stack for
1117 every process, showing its current stack trace.
1118 It is also used by various kernel debugging features that require
1119 stack trace generation.
1121 config DEBUG_KOBJECT
1122 bool "kobject debugging"
1123 depends on DEBUG_KERNEL
1125 If you say Y here, some extra kobject debugging messages will be sent
1128 config DEBUG_KOBJECT_RELEASE
1129 bool "kobject release debugging"
1130 depends on DEBUG_OBJECTS_TIMERS
1132 kobjects are reference counted objects. This means that their
1133 last reference count put is not predictable, and the kobject can
1134 live on past the point at which a driver decides to drop it's
1135 initial reference to the kobject gained on allocation. An
1136 example of this would be a struct device which has just been
1139 However, some buggy drivers assume that after such an operation,
1140 the memory backing the kobject can be immediately freed. This
1141 goes completely against the principles of a refcounted object.
1143 If you say Y here, the kernel will delay the release of kobjects
1144 on the last reference count to improve the visibility of this
1145 kind of kobject release bug.
1147 config HAVE_DEBUG_BUGVERBOSE
1150 config DEBUG_BUGVERBOSE
1151 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1152 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1155 Say Y here to make BUG() panics output the file name and line number
1156 of the BUG call as well as the EIP and oops trace. This aids
1157 debugging but costs about 70-100K of memory.
1160 bool "Debug linked list manipulation"
1161 depends on DEBUG_KERNEL
1163 Enable this to turn on extended checks in the linked-list
1168 config DEBUG_PI_LIST
1169 bool "Debug priority linked list manipulation"
1170 depends on DEBUG_KERNEL
1172 Enable this to turn on extended checks in the priority-ordered
1173 linked-list (plist) walking routines. This checks the entire
1174 list multiple times during each manipulation.
1179 bool "Debug SG table operations"
1180 depends on DEBUG_KERNEL
1182 Enable this to turn on checks on scatter-gather tables. This can
1183 help find problems with drivers that do not properly initialize
1188 config DEBUG_NOTIFIERS
1189 bool "Debug notifier call chains"
1190 depends on DEBUG_KERNEL
1192 Enable this to turn on sanity checking for notifier call chains.
1193 This is most useful for kernel developers to make sure that
1194 modules properly unregister themselves from notifier chains.
1195 This is a relatively cheap check but if you care about maximum
1198 config DEBUG_CREDENTIALS
1199 bool "Debug credential management"
1200 depends on DEBUG_KERNEL
1202 Enable this to turn on some debug checking for credential
1203 management. The additional code keeps track of the number of
1204 pointers from task_structs to any given cred struct, and checks to
1205 see that this number never exceeds the usage count of the cred
1208 Furthermore, if SELinux is enabled, this also checks that the
1209 security pointer in the cred struct is never seen to be invalid.
1213 menu "RCU Debugging"
1216 def_bool PROVE_LOCKING
1218 config PROVE_RCU_REPEATEDLY
1219 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1220 depends on PROVE_RCU
1223 By itself, PROVE_RCU will disable checking upon issuing the
1224 first warning (or "splat"). This feature prevents such
1225 disabling, allowing multiple RCU-lockdep warnings to be printed
1228 Say Y to allow multiple RCU-lockdep warnings per boot.
1230 Say N if you are unsure.
1232 config SPARSE_RCU_POINTER
1233 bool "RCU debugging: sparse-based checks for pointer usage"
1236 This feature enables the __rcu sparse annotation for
1237 RCU-protected pointers. This annotation will cause sparse
1238 to flag any non-RCU used of annotated pointers. This can be
1239 helpful when debugging RCU usage. Please note that this feature
1240 is not intended to enforce code cleanliness; it is instead merely
1243 Say Y to make sparse flag questionable use of RCU-protected pointers
1245 Say N if you are unsure.
1251 config RCU_TORTURE_TEST
1252 tristate "torture tests for RCU"
1253 depends on DEBUG_KERNEL
1259 This option provides a kernel module that runs torture tests
1260 on the RCU infrastructure. The kernel module may be built
1261 after the fact on the running kernel to be tested, if desired.
1263 Say Y here if you want RCU torture tests to be built into
1265 Say M if you want the RCU torture tests to build as a module.
1266 Say N if you are unsure.
1268 config RCU_TORTURE_TEST_RUNNABLE
1269 bool "torture tests for RCU runnable by default"
1270 depends on RCU_TORTURE_TEST = y
1273 This option provides a way to build the RCU torture tests
1274 directly into the kernel without them starting up at boot
1275 time. You can use /proc/sys/kernel/rcutorture_runnable
1276 to manually override this setting. This /proc file is
1277 available only when the RCU torture tests have been built
1280 Say Y here if you want the RCU torture tests to start during
1281 boot (you probably don't).
1282 Say N here if you want the RCU torture tests to start only
1283 after being manually enabled via /proc.
1285 config RCU_TORTURE_TEST_SLOW_PREINIT
1286 bool "Slow down RCU grace-period pre-initialization to expose races"
1287 depends on RCU_TORTURE_TEST
1289 This option delays grace-period pre-initialization (the
1290 propagation of CPU-hotplug changes up the rcu_node combining
1291 tree) for a few jiffies between initializing each pair of
1292 consecutive rcu_node structures. This helps to expose races
1293 involving grace-period pre-initialization, in other words, it
1294 makes your kernel less stable. It can also greatly increase
1295 grace-period latency, especially on systems with large numbers
1296 of CPUs. This is useful when torture-testing RCU, but in
1297 almost no other circumstance.
1299 Say Y here if you want your system to crash and hang more often.
1300 Say N if you want a sane system.
1302 config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
1303 int "How much to slow down RCU grace-period pre-initialization"
1306 depends on RCU_TORTURE_TEST_SLOW_PREINIT
1308 This option specifies the number of jiffies to wait between
1309 each rcu_node structure pre-initialization step.
1311 config RCU_TORTURE_TEST_SLOW_INIT
1312 bool "Slow down RCU grace-period initialization to expose races"
1313 depends on RCU_TORTURE_TEST
1315 This option delays grace-period initialization for a few
1316 jiffies between initializing each pair of consecutive
1317 rcu_node structures. This helps to expose races involving
1318 grace-period initialization, in other words, it makes your
1319 kernel less stable. It can also greatly increase grace-period
1320 latency, especially on systems with large numbers of CPUs.
1321 This is useful when torture-testing RCU, but in almost no
1324 Say Y here if you want your system to crash and hang more often.
1325 Say N if you want a sane system.
1327 config RCU_TORTURE_TEST_SLOW_INIT_DELAY
1328 int "How much to slow down RCU grace-period initialization"
1331 depends on RCU_TORTURE_TEST_SLOW_INIT
1333 This option specifies the number of jiffies to wait between
1334 each rcu_node structure initialization.
1336 config RCU_TORTURE_TEST_SLOW_CLEANUP
1337 bool "Slow down RCU grace-period cleanup to expose races"
1338 depends on RCU_TORTURE_TEST
1340 This option delays grace-period cleanup for a few jiffies
1341 between cleaning up each pair of consecutive rcu_node
1342 structures. This helps to expose races involving grace-period
1343 cleanup, in other words, it makes your kernel less stable.
1344 It can also greatly increase grace-period latency, especially
1345 on systems with large numbers of CPUs. This is useful when
1346 torture-testing RCU, but in almost no other circumstance.
1348 Say Y here if you want your system to crash and hang more often.
1349 Say N if you want a sane system.
1351 config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
1352 int "How much to slow down RCU grace-period cleanup"
1355 depends on RCU_TORTURE_TEST_SLOW_CLEANUP
1357 This option specifies the number of jiffies to wait between
1358 each rcu_node structure cleanup operation.
1360 config RCU_CPU_STALL_TIMEOUT
1361 int "RCU CPU stall timeout in seconds"
1362 depends on RCU_STALL_COMMON
1366 If a given RCU grace period extends more than the specified
1367 number of seconds, a CPU stall warning is printed. If the
1368 RCU grace period persists, additional CPU stall warnings are
1369 printed at more widely spaced intervals.
1372 bool "Enable tracing for RCU"
1373 depends on DEBUG_KERNEL
1376 This option provides tracing in RCU which presents stats
1377 in debugfs for debugging RCU implementation.
1379 Say Y here if you want to enable RCU tracing
1380 Say N if you are unsure.
1382 config RCU_EQS_DEBUG
1383 bool "Provide debugging asserts for adding NO_HZ support to an arch"
1384 depends on DEBUG_KERNEL
1386 This option provides consistency checks in RCU's handling of
1387 NO_HZ. These checks have proven quite helpful in detecting
1388 bugs in arch-specific NO_HZ code.
1390 Say N here if you need ultimate kernel/user switch latencies
1391 Say Y if you are unsure
1393 endmenu # "RCU Debugging"
1395 config DEBUG_BLOCK_EXT_DEVT
1396 bool "Force extended block device numbers and spread them"
1397 depends on DEBUG_KERNEL
1401 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1402 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1403 YOU ARE DOING. Distros, please enable this and fix whatever
1406 Conventionally, block device numbers are allocated from
1407 predetermined contiguous area. However, extended block area
1408 may introduce non-contiguous block device numbers. This
1409 option forces most block device numbers to be allocated from
1410 the extended space and spreads them to discover kernel or
1411 userland code paths which assume predetermined contiguous
1412 device number allocation.
1414 Note that turning on this debug option shuffles all the
1415 device numbers for all IDE and SCSI devices including libata
1416 ones, so root partition specified using device number
1417 directly (via rdev or root=MAJ:MIN) won't work anymore.
1418 Textual device names (root=/dev/sdXn) will continue to work.
1420 Say N if you are unsure.
1422 config NOTIFIER_ERROR_INJECTION
1423 tristate "Notifier error injection"
1424 depends on DEBUG_KERNEL
1427 This option provides the ability to inject artificial errors to
1428 specified notifier chain callbacks. It is useful to test the error
1429 handling of notifier call chain failures.
1433 config CPU_NOTIFIER_ERROR_INJECT
1434 tristate "CPU notifier error injection module"
1435 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1437 This option provides a kernel module that can be used to test
1438 the error handling of the cpu notifiers by injecting artificial
1439 errors to CPU notifier chain callbacks. It is controlled through
1440 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1442 If the notifier call chain should be failed with some events
1443 notified, write the error code to "actions/<notifier event>/error".
1445 Example: Inject CPU offline error (-1 == -EPERM)
1447 # cd /sys/kernel/debug/notifier-error-inject/cpu
1448 # echo -1 > actions/CPU_DOWN_PREPARE/error
1449 # echo 0 > /sys/devices/system/cpu/cpu1/online
1450 bash: echo: write error: Operation not permitted
1452 To compile this code as a module, choose M here: the module will
1453 be called cpu-notifier-error-inject.
1457 config PM_NOTIFIER_ERROR_INJECT
1458 tristate "PM notifier error injection module"
1459 depends on PM && NOTIFIER_ERROR_INJECTION
1460 default m if PM_DEBUG
1462 This option provides the ability to inject artificial errors to
1463 PM notifier chain callbacks. It is controlled through debugfs
1464 interface /sys/kernel/debug/notifier-error-inject/pm
1466 If the notifier call chain should be failed with some events
1467 notified, write the error code to "actions/<notifier event>/error".
1469 Example: Inject PM suspend error (-12 = -ENOMEM)
1471 # cd /sys/kernel/debug/notifier-error-inject/pm/
1472 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1473 # echo mem > /sys/power/state
1474 bash: echo: write error: Cannot allocate memory
1476 To compile this code as a module, choose M here: the module will
1477 be called pm-notifier-error-inject.
1481 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1482 tristate "OF reconfig notifier error injection module"
1483 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1485 This option provides the ability to inject artificial errors to
1486 OF reconfig notifier chain callbacks. It is controlled
1487 through debugfs interface under
1488 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1490 If the notifier call chain should be failed with some events
1491 notified, write the error code to "actions/<notifier event>/error".
1493 To compile this code as a module, choose M here: the module will
1494 be called of-reconfig-notifier-error-inject.
1498 config NETDEV_NOTIFIER_ERROR_INJECT
1499 tristate "Netdev notifier error injection module"
1500 depends on NET && NOTIFIER_ERROR_INJECTION
1502 This option provides the ability to inject artificial errors to
1503 netdevice notifier chain callbacks. It is controlled through debugfs
1504 interface /sys/kernel/debug/notifier-error-inject/netdev
1506 If the notifier call chain should be failed with some events
1507 notified, write the error code to "actions/<notifier event>/error".
1509 Example: Inject netdevice mtu change error (-22 = -EINVAL)
1511 # cd /sys/kernel/debug/notifier-error-inject/netdev
1512 # echo -22 > actions/NETDEV_CHANGEMTU/error
1513 # ip link set eth0 mtu 1024
1514 RTNETLINK answers: Invalid argument
1516 To compile this code as a module, choose M here: the module will
1517 be called netdev-notifier-error-inject.
1521 config FAULT_INJECTION
1522 bool "Fault-injection framework"
1523 depends on DEBUG_KERNEL
1525 Provide fault-injection framework.
1526 For more details, see Documentation/fault-injection/.
1529 bool "Fault-injection capability for kmalloc"
1530 depends on FAULT_INJECTION
1531 depends on SLAB || SLUB
1533 Provide fault-injection capability for kmalloc.
1535 config FAIL_PAGE_ALLOC
1536 bool "Fault-injection capabilitiy for alloc_pages()"
1537 depends on FAULT_INJECTION
1539 Provide fault-injection capability for alloc_pages().
1541 config FAIL_MAKE_REQUEST
1542 bool "Fault-injection capability for disk IO"
1543 depends on FAULT_INJECTION && BLOCK
1545 Provide fault-injection capability for disk IO.
1547 config FAIL_IO_TIMEOUT
1548 bool "Fault-injection capability for faking disk interrupts"
1549 depends on FAULT_INJECTION && BLOCK
1551 Provide fault-injection capability on end IO handling. This
1552 will make the block layer "forget" an interrupt as configured,
1553 thus exercising the error handling.
1555 Only works with drivers that use the generic timeout handling,
1556 for others it wont do anything.
1558 config FAIL_MMC_REQUEST
1559 bool "Fault-injection capability for MMC IO"
1560 depends on FAULT_INJECTION_DEBUG_FS && MMC
1562 Provide fault-injection capability for MMC IO.
1563 This will make the mmc core return data errors. This is
1564 useful to test the error handling in the mmc block device
1565 and to test how the mmc host driver handles retries from
1569 bool "Fault-injection capability for futexes"
1571 depends on FAULT_INJECTION && FUTEX
1573 Provide fault-injection capability for futexes.
1575 config FAULT_INJECTION_DEBUG_FS
1576 bool "Debugfs entries for fault-injection capabilities"
1577 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1579 Enable configuration of fault-injection capabilities via debugfs.
1581 config FAULT_INJECTION_STACKTRACE_FILTER
1582 bool "stacktrace filter for fault-injection capabilities"
1583 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1586 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1588 Provide stacktrace filter for fault-injection capabilities
1591 bool "Latency measuring infrastructure"
1592 depends on HAVE_LATENCYTOP_SUPPORT
1593 depends on DEBUG_KERNEL
1594 depends on STACKTRACE_SUPPORT
1596 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1603 Enable this option if you want to use the LatencyTOP tool
1604 to find out which userspace is blocking on what kernel operations.
1606 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1609 config DEBUG_STRICT_USER_COPY_CHECKS
1610 bool "Strict user copy size checks"
1611 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1612 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1614 Enabling this option turns a certain set of sanity checks for user
1615 copy operations into compile time failures.
1617 The copy_from_user() etc checks are there to help test if there
1618 are sufficient security checks on the length argument of
1619 the copy operation, by having gcc prove that the argument is
1624 source kernel/trace/Kconfig
1626 menu "Runtime Testing"
1629 tristate "Linux Kernel Dump Test Tool Module"
1634 This module enables testing of the different dumping mechanisms by
1635 inducing system failures at predefined crash points.
1636 If you don't need it: say N
1637 Choose M here to compile this code as a module. The module will be
1640 Documentation on how to use the module can be found in
1641 Documentation/fault-injection/provoke-crashes.txt
1643 config TEST_LIST_SORT
1644 bool "Linked list sorting test"
1645 depends on DEBUG_KERNEL
1647 Enable this to turn on 'list_sort()' function test. This test is
1648 executed only once during system boot, so affects only boot time.
1652 config KPROBES_SANITY_TEST
1653 bool "Kprobes sanity tests"
1654 depends on DEBUG_KERNEL
1658 This option provides for testing basic kprobes functionality on
1659 boot. A sample kprobe, jprobe and kretprobe are inserted and
1660 verified for functionality.
1662 Say N if you are unsure.
1664 config BACKTRACE_SELF_TEST
1665 tristate "Self test for the backtrace code"
1666 depends on DEBUG_KERNEL
1669 This option provides a kernel module that can be used to test
1670 the kernel stack backtrace code. This option is not useful
1671 for distributions or general kernels, but only for kernel
1672 developers working on architecture code.
1674 Note that if you want to also test saved backtraces, you will
1675 have to enable STACKTRACE as well.
1677 Say N if you are unsure.
1680 tristate "Red-Black tree test"
1681 depends on DEBUG_KERNEL
1683 A benchmark measuring the performance of the rbtree library.
1684 Also includes rbtree invariant checks.
1686 config INTERVAL_TREE_TEST
1687 tristate "Interval tree test"
1688 depends on m && DEBUG_KERNEL
1689 select INTERVAL_TREE
1691 A benchmark measuring the performance of the interval tree library
1694 tristate "Per cpu operations test"
1695 depends on m && DEBUG_KERNEL
1697 Enable this option to build test module which validates per-cpu
1702 config ATOMIC64_SELFTEST
1703 bool "Perform an atomic64_t self-test at boot"
1705 Enable this option to test the atomic64_t functions at boot.
1709 config ASYNC_RAID6_TEST
1710 tristate "Self test for hardware accelerated raid6 recovery"
1711 depends on ASYNC_RAID6_RECOV
1714 This is a one-shot self test that permutes through the
1715 recovery of all the possible two disk failure scenarios for a
1716 N-disk array. Recovery is performed with the asynchronous
1717 raid6 recovery routines, and will optionally use an offload
1718 engine if one is available.
1723 tristate "Test functions located in the hexdump module at runtime"
1725 config TEST_STRING_HELPERS
1726 tristate "Test functions located in the string_helpers module at runtime"
1729 tristate "Test kstrto*() family of functions at runtime"
1732 tristate "Test printf() family of functions at runtime"
1734 config TEST_RHASHTABLE
1735 tristate "Perform selftest on resizable hash table"
1738 Enable this option to test the rhashtable functions at boot.
1742 endmenu # runtime tests
1744 config PROVIDE_OHCI1394_DMA_INIT
1745 bool "Remote debugging over FireWire early on boot"
1746 depends on PCI && X86
1748 If you want to debug problems which hang or crash the kernel early
1749 on boot and the crashing machine has a FireWire port, you can use
1750 this feature to remotely access the memory of the crashed machine
1751 over FireWire. This employs remote DMA as part of the OHCI1394
1752 specification which is now the standard for FireWire controllers.
1754 With remote DMA, you can monitor the printk buffer remotely using
1755 firescope and access all memory below 4GB using fireproxy from gdb.
1756 Even controlling a kernel debugger is possible using remote DMA.
1760 If ohci1394_dma=early is used as boot parameter, it will initialize
1761 all OHCI1394 controllers which are found in the PCI config space.
1763 As all changes to the FireWire bus such as enabling and disabling
1764 devices cause a bus reset and thereby disable remote DMA for all
1765 devices, be sure to have the cable plugged and FireWire enabled on
1766 the debugging host before booting the debug target for debugging.
1768 This code (~1k) is freed after boot. By then, the firewire stack
1769 in charge of the OHCI-1394 controllers should be used instead.
1771 See Documentation/debugging-via-ohci1394.txt for more information.
1774 bool "Build targets in Documentation/ tree"
1775 depends on HEADERS_CHECK
1777 This option attempts to build objects from the source files in the
1778 kernel Documentation/ tree.
1780 Say N if you are unsure.
1782 config DMA_API_DEBUG
1783 bool "Enable debugging of DMA-API usage"
1784 depends on HAVE_DMA_API_DEBUG
1786 Enable this option to debug the use of the DMA API by device drivers.
1787 With this option you will be able to detect common bugs in device
1788 drivers like double-freeing of DMA mappings or freeing mappings that
1789 were never allocated.
1791 This also attempts to catch cases where a page owned by DMA is
1792 accessed by the cpu in a way that could cause data corruption. For
1793 example, this enables cow_user_page() to check that the source page is
1796 This option causes a performance degradation. Use only if you want to
1797 debug device drivers and dma interactions.
1802 tristate "Test module loading with 'hello world' module"
1806 This builds the "test_module" module that emits "Hello, world"
1807 on printk when loaded. It is designed to be used for basic
1808 evaluation of the module loading subsystem (for example when
1809 validating module verification). It lacks any extra dependencies,
1810 and will not normally be loaded by the system unless explicitly
1815 config TEST_USER_COPY
1816 tristate "Test user/kernel boundary protections"
1820 This builds the "test_user_copy" module that runs sanity checks
1821 on the copy_to/from_user infrastructure, making sure basic
1822 user/kernel boundary testing is working. If it fails to load,
1823 a regression has been detected in the user/kernel memory boundary
1829 tristate "Test BPF filter functionality"
1833 This builds the "test_bpf" module that runs various test vectors
1834 against the BPF interpreter or BPF JIT compiler depending on the
1835 current setting. This is in particular useful for BPF JIT compiler
1836 development, but also to run regression tests against changes in
1837 the interpreter code. It also enables test stubs for eBPF maps and
1838 verifier used by user space verifier testsuite.
1842 config TEST_FIRMWARE
1843 tristate "Test firmware loading via userspace interface"
1845 depends on FW_LOADER
1847 This builds the "test_firmware" module that creates a userspace
1848 interface for testing firmware loading. This can be used to
1849 control the triggering of firmware loading without needing an
1850 actual firmware-using device. The contents can be rechecked by
1856 tristate "udelay test driver"
1859 This builds the "udelay_test" module that helps to make sure
1860 that udelay() is working properly.
1866 depends on HAVE_MEMBLOCK
1868 This option adds a kernel parameter 'memtest', which allows memtest
1870 memtest=0, mean disabled; -- default
1871 memtest=1, mean do 1 test pattern;
1873 memtest=17, mean do 17 test patterns.
1874 If you are unsure how to answer this question, answer N.
1876 config TEST_STATIC_KEYS
1877 tristate "Test static keys"
1881 Test the static key interfaces.
1885 source "samples/Kconfig"
1887 source "lib/Kconfig.kgdb"
projects / cascardo / linux.git / blob