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 DEFAULT_MESSAGE_LOGLEVEL
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 ENABLE_WARN_DEPRECATED
147 bool "Enable __deprecated logic"
150 Enable the __deprecated logic in the kernel build.
151 Disable this to suppress the "warning: 'foo' is deprecated
152 (declared at kernel/power/somefile.c:1234)" messages.
154 config ENABLE_MUST_CHECK
155 bool "Enable __must_check logic"
158 Enable the __must_check logic in the kernel build. Disable this to
159 suppress the "warning: ignoring return value of 'foo', declared with
160 attribute warn_unused_result" messages.
163 int "Warn for stack frames larger than (needs gcc 4.4)"
165 default 1024 if !64BIT
166 default 2048 if 64BIT
168 Tell gcc to warn at build time for stack frames larger than this.
169 Setting this too low will cause a lot of warnings.
170 Setting it to 0 disables the warning.
173 config STRIP_ASM_SYMS
174 bool "Strip assembler-generated symbols during link"
177 Strip internal assembler-generated symbols during a link (symbols
178 that look like '.Lxxx') so they don't pollute the output of
179 get_wchan() and suchlike.
182 bool "Generate readable assembler code"
183 depends on DEBUG_KERNEL
185 Disable some compiler optimizations that tend to generate human unreadable
186 assembler output. This may make the kernel slightly slower, but it helps
187 to keep kernel developers who have to stare a lot at assembler listings
190 config UNUSED_SYMBOLS
191 bool "Enable unused/obsolete exported symbols"
194 Unused but exported symbols make the kernel needlessly bigger. For
195 that reason most of these unused exports will soon be removed. This
196 option is provided temporarily to provide a transition period in case
197 some external kernel module needs one of these symbols anyway. If you
198 encounter such a case in your module, consider if you are actually
199 using the right API. (rationale: since nobody in the kernel is using
200 this in a module, there is a pretty good chance it's actually the
201 wrong interface to use). If you really need the symbol, please send a
202 mail to the linux kernel mailing list mentioning the symbol and why
203 you really need it, and what the merge plan to the mainline kernel for
207 bool "Debug Filesystem"
209 debugfs is a virtual file system that kernel developers use to put
210 debugging files into. Enable this option to be able to read and
211 write to these files.
213 For detailed documentation on the debugfs API, see
214 Documentation/DocBook/filesystems.
219 bool "Run 'make headers_check' when building vmlinux"
222 This option will extract the user-visible kernel headers whenever
223 building the kernel, and will run basic sanity checks on them to
224 ensure that exported files do not attempt to include files which
225 were not exported, etc.
227 If you're making modifications to header files which are
228 relevant for userspace, say 'Y', and check the headers
229 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
230 your build tree), to make sure they're suitable.
232 config DEBUG_SECTION_MISMATCH
233 bool "Enable full Section mismatch analysis"
235 The section mismatch analysis checks if there are illegal
236 references from one section to another section.
237 During linktime or runtime, some sections are dropped;
238 any use of code/data previously in these sections would
239 most likely result in an oops.
240 In the code, functions and variables are annotated with
241 __init,, etc. (see the full list in include/linux/init.h),
242 which results in the code/data being placed in specific sections.
243 The section mismatch analysis is always performed after a full
244 kernel build, and enabling this option causes the following
245 additional steps to occur:
246 - Add the option -fno-inline-functions-called-once to gcc commands.
247 When inlining a function annotated with __init in a non-init
248 function, we would lose the section information and thus
249 the analysis would not catch the illegal reference.
250 This option tells gcc to inline less (but it does result in
252 - Run the section mismatch analysis for each module/built-in.o file.
253 When we run the section mismatch analysis on vmlinux.o, we
254 lose valueble information about where the mismatch was
256 Running the analysis for each module/built-in.o file
257 tells where the mismatch happens much closer to the
258 source. The drawback is that the same mismatch is
259 reported at least twice.
260 - Enable verbose reporting from modpost in order to help resolve
261 the section mismatches that are reported.
264 # Select this config option from the architecture Kconfig, if it
265 # is preferred to always offer frame pointers as a config
266 # option on the architecture (regardless of KERNEL_DEBUG):
268 config ARCH_WANT_FRAME_POINTERS
273 bool "Compile the kernel with frame pointers"
274 depends on DEBUG_KERNEL && \
275 (CRIS || M68K || FRV || UML || \
276 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
277 ARCH_WANT_FRAME_POINTERS
278 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
280 If you say Y here the resulting kernel image will be slightly
281 larger and slower, but it gives very useful debugging information
282 in case of kernel bugs. (precise oopses/stacktraces/warnings)
284 config DEBUG_FORCE_WEAK_PER_CPU
285 bool "Force weak per-cpu definitions"
286 depends on DEBUG_KERNEL
288 s390 and alpha require percpu variables in modules to be
289 defined weak to work around addressing range issue which
290 puts the following two restrictions on percpu variable
293 1. percpu symbols must be unique whether static or not
294 2. percpu variables can't be defined inside a function
296 To ensure that generic code follows the above rules, this
297 option forces all percpu variables to be defined as weak.
299 endmenu # "Compiler options"
302 bool "Magic SysRq key"
305 If you say Y here, you will have some control over the system even
306 if the system crashes for example during kernel debugging (e.g., you
307 will be able to flush the buffer cache to disk, reboot the system
308 immediately or dump some status information). This is accomplished
309 by pressing various keys while holding SysRq (Alt+PrintScreen). It
310 also works on a serial console (on PC hardware at least), if you
311 send a BREAK and then within 5 seconds a command keypress. The
312 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
313 unless you really know what this hack does.
315 config MAGIC_SYSRQ_DEFAULT_ENABLE
316 hex "Enable magic SysRq key functions by default"
317 depends on MAGIC_SYSRQ
320 Specifies which SysRq key functions are enabled by default.
321 This may be set to 1 or 0 to enable or disable them all, or
322 to a bitmask as described in Documentation/sysrq.txt.
325 bool "Kernel debugging"
327 Say Y here if you are developing drivers or trying to debug and
328 identify kernel problems.
330 menu "Memory Debugging"
332 source mm/Kconfig.debug
335 bool "Debug object operations"
336 depends on DEBUG_KERNEL
338 If you say Y here, additional code will be inserted into the
339 kernel to track the life time of various objects and validate
340 the operations on those objects.
342 config DEBUG_OBJECTS_SELFTEST
343 bool "Debug objects selftest"
344 depends on DEBUG_OBJECTS
346 This enables the selftest of the object debug code.
348 config DEBUG_OBJECTS_FREE
349 bool "Debug objects in freed memory"
350 depends on DEBUG_OBJECTS
352 This enables checks whether a k/v free operation frees an area
353 which contains an object which has not been deactivated
354 properly. This can make kmalloc/kfree-intensive workloads
357 config DEBUG_OBJECTS_TIMERS
358 bool "Debug timer objects"
359 depends on DEBUG_OBJECTS
361 If you say Y here, additional code will be inserted into the
362 timer routines to track the life time of timer objects and
363 validate the timer operations.
365 config DEBUG_OBJECTS_WORK
366 bool "Debug work objects"
367 depends on DEBUG_OBJECTS
369 If you say Y here, additional code will be inserted into the
370 work queue routines to track the life time of work objects and
371 validate the work operations.
373 config DEBUG_OBJECTS_RCU_HEAD
374 bool "Debug RCU callbacks objects"
375 depends on DEBUG_OBJECTS
377 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
379 config DEBUG_OBJECTS_PERCPU_COUNTER
380 bool "Debug percpu counter objects"
381 depends on DEBUG_OBJECTS
383 If you say Y here, additional code will be inserted into the
384 percpu counter routines to track the life time of percpu counter
385 objects and validate the percpu counter operations.
387 config DEBUG_OBJECTS_ENABLE_DEFAULT
388 int "debug_objects bootup default value (0-1)"
391 depends on DEBUG_OBJECTS
393 Debug objects boot parameter default value
396 bool "Debug slab memory allocations"
397 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
399 Say Y here to have the kernel do limited verification on memory
400 allocation as well as poisoning memory on free to catch use of freed
401 memory. This can make kmalloc/kfree-intensive workloads much slower.
403 config DEBUG_SLAB_LEAK
404 bool "Memory leak debugging"
405 depends on DEBUG_SLAB
408 bool "SLUB debugging on by default"
409 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
412 Boot with debugging on by default. SLUB boots by default with
413 the runtime debug capabilities switched off. Enabling this is
414 equivalent to specifying the "slub_debug" parameter on boot.
415 There is no support for more fine grained debug control like
416 possible with slub_debug=xxx. SLUB debugging may be switched
417 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
422 bool "Enable SLUB performance statistics"
423 depends on SLUB && SYSFS
425 SLUB statistics are useful to debug SLUBs allocation behavior in
426 order find ways to optimize the allocator. This should never be
427 enabled for production use since keeping statistics slows down
428 the allocator by a few percentage points. The slabinfo command
429 supports the determination of the most active slabs to figure
430 out which slabs are relevant to a particular load.
431 Try running: slabinfo -DA
433 config HAVE_DEBUG_KMEMLEAK
436 config DEBUG_KMEMLEAK
437 bool "Kernel memory leak detector"
438 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
440 select STACKTRACE if STACKTRACE_SUPPORT
444 Say Y here if you want to enable the memory leak
445 detector. The memory allocation/freeing is traced in a way
446 similar to the Boehm's conservative garbage collector, the
447 difference being that the orphan objects are not freed but
448 only shown in /sys/kernel/debug/kmemleak. Enabling this
449 feature will introduce an overhead to memory
450 allocations. See Documentation/kmemleak.txt for more
453 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
454 of finding leaks due to the slab objects poisoning.
456 In order to access the kmemleak file, debugfs needs to be
457 mounted (usually at /sys/kernel/debug).
459 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
460 int "Maximum kmemleak early log entries"
461 depends on DEBUG_KMEMLEAK
465 Kmemleak must track all the memory allocations to avoid
466 reporting false positives. Since memory may be allocated or
467 freed before kmemleak is initialised, an early log buffer is
468 used to store these actions. If kmemleak reports "early log
469 buffer exceeded", please increase this value.
471 config DEBUG_KMEMLEAK_TEST
472 tristate "Simple test for the kernel memory leak detector"
473 depends on DEBUG_KMEMLEAK && m
475 This option enables a module that explicitly leaks memory.
479 config DEBUG_KMEMLEAK_DEFAULT_OFF
480 bool "Default kmemleak to off"
481 depends on DEBUG_KMEMLEAK
483 Say Y here to disable kmemleak by default. It can then be enabled
484 on the command line via kmemleak=on.
486 config DEBUG_STACK_USAGE
487 bool "Stack utilization instrumentation"
488 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
490 Enables the display of the minimum amount of free stack which each
491 task has ever had available in the sysrq-T and sysrq-P debug output.
493 This option will slow down process creation somewhat.
497 depends on DEBUG_KERNEL
499 Enable this to turn on extended checks in the virtual-memory system
500 that may impact performance.
505 bool "Debug VM red-black trees"
508 Enable this to turn on more extended checks in the virtual-memory
509 system that may impact performance.
514 bool "Debug VM translations"
515 depends on DEBUG_KERNEL && X86
517 Enable some costly sanity checks in virtual to page code. This can
518 catch mistakes with virt_to_page() and friends.
522 config DEBUG_NOMMU_REGIONS
523 bool "Debug the global anon/private NOMMU mapping region tree"
524 depends on DEBUG_KERNEL && !MMU
526 This option causes the global tree of anonymous and private mapping
527 regions to be regularly checked for invalid topology.
529 config DEBUG_MEMORY_INIT
530 bool "Debug memory initialisation" if EXPERT
533 Enable this for additional checks during memory initialisation.
534 The sanity checks verify aspects of the VM such as the memory model
535 and other information provided by the architecture. Verbose
536 information will be printed at KERN_DEBUG loglevel depending
537 on the mminit_loglevel= command-line option.
541 config MEMORY_NOTIFIER_ERROR_INJECT
542 tristate "Memory hotplug notifier error injection module"
543 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
545 This option provides the ability to inject artificial errors to
546 memory hotplug notifier chain callbacks. It is controlled through
547 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
549 If the notifier call chain should be failed with some events
550 notified, write the error code to "actions/<notifier event>/error".
552 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
554 # cd /sys/kernel/debug/notifier-error-inject/memory
555 # echo -12 > actions/MEM_GOING_OFFLINE/error
556 # echo offline > /sys/devices/system/memory/memoryXXX/state
557 bash: echo: write error: Cannot allocate memory
559 To compile this code as a module, choose M here: the module will
560 be called memory-notifier-error-inject.
564 config DEBUG_PER_CPU_MAPS
565 bool "Debug access to per_cpu maps"
566 depends on DEBUG_KERNEL
569 Say Y to verify that the per_cpu map being accessed has
570 been set up. This adds a fair amount of code to kernel memory
571 and decreases performance.
576 bool "Highmem debugging"
577 depends on DEBUG_KERNEL && HIGHMEM
579 This options enables addition error checking for high memory systems.
580 Disable for production systems.
582 config HAVE_DEBUG_STACKOVERFLOW
585 config DEBUG_STACKOVERFLOW
586 bool "Check for stack overflows"
587 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
589 Say Y here if you want to check for overflows of kernel, IRQ
590 and exception stacks (if your archicture uses them). This
591 option will show detailed messages if free stack space drops
592 below a certain limit.
594 These kinds of bugs usually occur when call-chains in the
595 kernel get too deep, especially when interrupts are
598 Use this in cases where you see apparently random memory
599 corruption, especially if it appears in 'struct thread_info'
601 If in doubt, say "N".
603 source "lib/Kconfig.kmemcheck"
605 endmenu # "Memory Debugging"
608 bool "Debug shared IRQ handlers"
609 depends on DEBUG_KERNEL
611 Enable this to generate a spurious interrupt as soon as a shared
612 interrupt handler is registered, and just before one is deregistered.
613 Drivers ought to be able to handle interrupts coming in at those
614 points; some don't and need to be caught.
616 menu "Debug Lockups and Hangs"
618 config LOCKUP_DETECTOR
619 bool "Detect Hard and Soft Lockups"
620 depends on DEBUG_KERNEL && !S390
622 Say Y here to enable the kernel to act as a watchdog to detect
623 hard and soft lockups.
625 Softlockups are bugs that cause the kernel to loop in kernel
626 mode for more than 20 seconds, without giving other tasks a
627 chance to run. The current stack trace is displayed upon
628 detection and the system will stay locked up.
630 Hardlockups are bugs that cause the CPU to loop in kernel mode
631 for more than 10 seconds, without letting other interrupts have a
632 chance to run. The current stack trace is displayed upon detection
633 and the system will stay locked up.
635 The overhead should be minimal. A periodic hrtimer runs to
636 generate interrupts and kick the watchdog task every 4 seconds.
637 An NMI is generated every 10 seconds or so to check for hardlockups.
639 The frequency of hrtimer and NMI events and the soft and hard lockup
640 thresholds can be controlled through the sysctl watchdog_thresh.
642 config HARDLOCKUP_DETECTOR
644 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
645 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
647 config BOOTPARAM_HARDLOCKUP_PANIC
648 bool "Panic (Reboot) On Hard Lockups"
649 depends on HARDLOCKUP_DETECTOR
651 Say Y here to enable the kernel to panic on "hard lockups",
652 which are bugs that cause the kernel to loop in kernel
653 mode with interrupts disabled for more than 10 seconds (configurable
654 using the watchdog_thresh sysctl).
658 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
660 depends on HARDLOCKUP_DETECTOR
662 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
663 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
665 config BOOTPARAM_SOFTLOCKUP_PANIC
666 bool "Panic (Reboot) On Soft Lockups"
667 depends on LOCKUP_DETECTOR
669 Say Y here to enable the kernel to panic on "soft lockups",
670 which are bugs that cause the kernel to loop in kernel
671 mode for more than 20 seconds (configurable using the watchdog_thresh
672 sysctl), without giving other tasks a chance to run.
674 The panic can be used in combination with panic_timeout,
675 to cause the system to reboot automatically after a
676 lockup has been detected. This feature is useful for
677 high-availability systems that have uptime guarantees and
678 where a lockup must be resolved ASAP.
682 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
684 depends on LOCKUP_DETECTOR
686 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
687 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
689 config DETECT_HUNG_TASK
690 bool "Detect Hung Tasks"
691 depends on DEBUG_KERNEL
692 default LOCKUP_DETECTOR
694 Say Y here to enable the kernel to detect "hung tasks",
695 which are bugs that cause the task to be stuck in
696 uninterruptible "D" state indefinitiley.
698 When a hung task is detected, the kernel will print the
699 current stack trace (which you should report), but the
700 task will stay in uninterruptible state. If lockdep is
701 enabled then all held locks will also be reported. This
702 feature has negligible overhead.
704 config DEFAULT_HUNG_TASK_TIMEOUT
705 int "Default timeout for hung task detection (in seconds)"
706 depends on DETECT_HUNG_TASK
709 This option controls the default timeout (in seconds) used
710 to determine when a task has become non-responsive and should
713 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
714 sysctl or by writing a value to
715 /proc/sys/kernel/hung_task_timeout_secs.
717 A timeout of 0 disables the check. The default is two minutes.
718 Keeping the default should be fine in most cases.
720 config BOOTPARAM_HUNG_TASK_PANIC
721 bool "Panic (Reboot) On Hung Tasks"
722 depends on DETECT_HUNG_TASK
724 Say Y here to enable the kernel to panic on "hung tasks",
725 which are bugs that cause the kernel to leave a task stuck
726 in uninterruptible "D" state.
728 The panic can be used in combination with panic_timeout,
729 to cause the system to reboot automatically after a
730 hung task has been detected. This feature is useful for
731 high-availability systems that have uptime guarantees and
732 where a hung tasks must be resolved ASAP.
736 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
738 depends on DETECT_HUNG_TASK
740 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
741 default 1 if BOOTPARAM_HUNG_TASK_PANIC
743 endmenu # "Debug lockups and hangs"
748 Say Y here to enable the kernel to panic when it oopses. This
749 has the same effect as setting oops=panic on the kernel command
752 This feature is useful to ensure that the kernel does not do
753 anything erroneous after an oops which could result in data
754 corruption or other issues.
758 config PANIC_ON_OOPS_VALUE
761 default 0 if !PANIC_ON_OOPS
762 default 1 if PANIC_ON_OOPS
768 Set the timeout value (in seconds) until a reboot occurs when the
769 the kernel panics. If n = 0, then we wait forever. A timeout
770 value n > 0 will wait n seconds before rebooting, while a timeout
771 value n < 0 will reboot immediately.
774 bool "Collect scheduler debugging info"
775 depends on DEBUG_KERNEL && PROC_FS
778 If you say Y here, the /proc/sched_debug file will be provided
779 that can help debug the scheduler. The runtime overhead of this
783 bool "Collect scheduler statistics"
784 depends on DEBUG_KERNEL && PROC_FS
786 If you say Y here, additional code will be inserted into the
787 scheduler and related routines to collect statistics about
788 scheduler behavior and provide them in /proc/schedstat. These
789 stats may be useful for both tuning and debugging the scheduler
790 If you aren't debugging the scheduler or trying to tune a specific
791 application, you can say N to avoid the very slight overhead
795 bool "Collect kernel timers statistics"
796 depends on DEBUG_KERNEL && PROC_FS
798 If you say Y here, additional code will be inserted into the
799 timer routines to collect statistics about kernel timers being
800 reprogrammed. The statistics can be read from /proc/timer_stats.
801 The statistics collection is started by writing 1 to /proc/timer_stats,
802 writing 0 stops it. This feature is useful to collect information
803 about timer usage patterns in kernel and userspace. This feature
804 is lightweight if enabled in the kernel config but not activated
805 (it defaults to deactivated on bootup and will only be activated
806 if some application like powertop activates it explicitly).
809 bool "Debug preemptible kernel"
810 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
813 If you say Y here then the kernel will use a debug variant of the
814 commonly used smp_processor_id() function and will print warnings
815 if kernel code uses it in a preemption-unsafe way. Also, the kernel
816 will detect preemption count underflows.
818 menu "Lock Debugging (spinlocks, mutexes, etc...)"
820 config DEBUG_RT_MUTEXES
821 bool "RT Mutex debugging, deadlock detection"
822 depends on DEBUG_KERNEL && RT_MUTEXES
824 This allows rt mutex semantics violations and rt mutex related
825 deadlocks (lockups) to be detected and reported automatically.
830 depends on DEBUG_RT_MUTEXES
832 config RT_MUTEX_TESTER
833 bool "Built-in scriptable tester for rt-mutexes"
834 depends on DEBUG_KERNEL && RT_MUTEXES
836 This option enables a rt-mutex tester.
838 config DEBUG_SPINLOCK
839 bool "Spinlock and rw-lock debugging: basic checks"
840 depends on DEBUG_KERNEL
841 select UNINLINE_SPIN_UNLOCK
843 Say Y here and build SMP to catch missing spinlock initialization
844 and certain other kinds of spinlock errors commonly made. This is
845 best used in conjunction with the NMI watchdog so that spinlock
846 deadlocks are also debuggable.
849 bool "Mutex debugging: basic checks"
850 depends on DEBUG_KERNEL
852 This feature allows mutex semantics violations to be detected and
855 config DEBUG_WW_MUTEX_SLOWPATH
856 bool "Wait/wound mutex debugging: Slowpath testing"
857 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
858 select DEBUG_LOCK_ALLOC
859 select DEBUG_SPINLOCK
862 This feature enables slowpath testing for w/w mutex users by
863 injecting additional -EDEADLK wound/backoff cases. Together with
864 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
865 will test all possible w/w mutex interface abuse with the
866 exception of simply not acquiring all the required locks.
868 config DEBUG_LOCK_ALLOC
869 bool "Lock debugging: detect incorrect freeing of live locks"
870 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
871 select DEBUG_SPINLOCK
875 This feature will check whether any held lock (spinlock, rwlock,
876 mutex or rwsem) is incorrectly freed by the kernel, via any of the
877 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
878 vfree(), etc.), whether a live lock is incorrectly reinitialized via
879 spin_lock_init()/mutex_init()/etc., or whether there is any lock
880 held during task exit.
883 bool "Lock debugging: prove locking correctness"
884 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
886 select DEBUG_SPINLOCK
888 select DEBUG_LOCK_ALLOC
889 select TRACE_IRQFLAGS
892 This feature enables the kernel to prove that all locking
893 that occurs in the kernel runtime is mathematically
894 correct: that under no circumstance could an arbitrary (and
895 not yet triggered) combination of observed locking
896 sequences (on an arbitrary number of CPUs, running an
897 arbitrary number of tasks and interrupt contexts) cause a
900 In short, this feature enables the kernel to report locking
901 related deadlocks before they actually occur.
903 The proof does not depend on how hard and complex a
904 deadlock scenario would be to trigger: how many
905 participant CPUs, tasks and irq-contexts would be needed
906 for it to trigger. The proof also does not depend on
907 timing: if a race and a resulting deadlock is possible
908 theoretically (no matter how unlikely the race scenario
909 is), it will be proven so and will immediately be
910 reported by the kernel (once the event is observed that
911 makes the deadlock theoretically possible).
913 If a deadlock is impossible (i.e. the locking rules, as
914 observed by the kernel, are mathematically correct), the
915 kernel reports nothing.
917 NOTE: this feature can also be enabled for rwlocks, mutexes
918 and rwsems - in which case all dependencies between these
919 different locking variants are observed and mapped too, and
920 the proof of observed correctness is also maintained for an
921 arbitrary combination of these separate locking variants.
923 For more details, see Documentation/lockdep-design.txt.
927 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
929 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC
934 bool "Lock usage statistics"
935 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
937 select DEBUG_SPINLOCK
939 select DEBUG_LOCK_ALLOC
942 This feature enables tracking lock contention points
944 For more details, see Documentation/lockstat.txt
946 This also enables lock events required by "perf lock",
948 If you want to use "perf lock", you also need to turn on
949 CONFIG_EVENT_TRACING.
951 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
952 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
955 bool "Lock dependency engine debugging"
956 depends on DEBUG_KERNEL && LOCKDEP
958 If you say Y here, the lock dependency engine will do
959 additional runtime checks to debug itself, at the price
960 of more runtime overhead.
962 config DEBUG_ATOMIC_SLEEP
963 bool "Sleep inside atomic section checking"
965 depends on DEBUG_KERNEL
967 If you say Y here, various routines which may sleep will become very
968 noisy if they are called inside atomic sections: when a spinlock is
969 held, inside an rcu read side critical section, inside preempt disabled
970 sections, inside an interrupt, etc...
972 config DEBUG_LOCKING_API_SELFTESTS
973 bool "Locking API boot-time self-tests"
974 depends on DEBUG_KERNEL
976 Say Y here if you want the kernel to run a short self-test during
977 bootup. The self-test checks whether common types of locking bugs
978 are detected by debugging mechanisms or not. (if you disable
979 lock debugging then those bugs wont be detected of course.)
980 The following locking APIs are covered: spinlocks, rwlocks,
983 config LOCK_TORTURE_TEST
984 tristate "torture tests for locking"
985 depends on DEBUG_KERNEL
989 This option provides a kernel module that runs torture tests
990 on kernel locking primitives. The kernel module may be built
991 after the fact on the running kernel to be tested, if desired.
993 Say Y here if you want kernel locking-primitive torture tests
994 to be built into the kernel.
995 Say M if you want these torture tests to build as a module.
996 Say N if you are unsure.
998 endmenu # lock debugging
1000 config TRACE_IRQFLAGS
1003 Enables hooks to interrupt enabling and disabling for
1004 either tracing or lock debugging.
1008 depends on STACKTRACE_SUPPORT
1010 config DEBUG_KOBJECT
1011 bool "kobject debugging"
1012 depends on DEBUG_KERNEL
1014 If you say Y here, some extra kobject debugging messages will be sent
1017 config DEBUG_KOBJECT_RELEASE
1018 bool "kobject release debugging"
1019 depends on DEBUG_OBJECTS_TIMERS
1021 kobjects are reference counted objects. This means that their
1022 last reference count put is not predictable, and the kobject can
1023 live on past the point at which a driver decides to drop it's
1024 initial reference to the kobject gained on allocation. An
1025 example of this would be a struct device which has just been
1028 However, some buggy drivers assume that after such an operation,
1029 the memory backing the kobject can be immediately freed. This
1030 goes completely against the principles of a refcounted object.
1032 If you say Y here, the kernel will delay the release of kobjects
1033 on the last reference count to improve the visibility of this
1034 kind of kobject release bug.
1036 config HAVE_DEBUG_BUGVERBOSE
1039 config DEBUG_BUGVERBOSE
1040 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1041 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1044 Say Y here to make BUG() panics output the file name and line number
1045 of the BUG call as well as the EIP and oops trace. This aids
1046 debugging but costs about 70-100K of memory.
1049 bool "Debug linked list manipulation"
1050 depends on DEBUG_KERNEL
1052 Enable this to turn on extended checks in the linked-list
1058 bool "Debug SG table operations"
1059 depends on DEBUG_KERNEL
1061 Enable this to turn on checks on scatter-gather tables. This can
1062 help find problems with drivers that do not properly initialize
1067 config DEBUG_NOTIFIERS
1068 bool "Debug notifier call chains"
1069 depends on DEBUG_KERNEL
1071 Enable this to turn on sanity checking for notifier call chains.
1072 This is most useful for kernel developers to make sure that
1073 modules properly unregister themselves from notifier chains.
1074 This is a relatively cheap check but if you care about maximum
1077 config DEBUG_CREDENTIALS
1078 bool "Debug credential management"
1079 depends on DEBUG_KERNEL
1081 Enable this to turn on some debug checking for credential
1082 management. The additional code keeps track of the number of
1083 pointers from task_structs to any given cred struct, and checks to
1084 see that this number never exceeds the usage count of the cred
1087 Furthermore, if SELinux is enabled, this also checks that the
1088 security pointer in the cred struct is never seen to be invalid.
1092 menu "RCU Debugging"
1095 bool "RCU debugging: prove RCU correctness"
1096 depends on PROVE_LOCKING
1099 This feature enables lockdep extensions that check for correct
1100 use of RCU APIs. This is currently under development. Say Y
1101 if you want to debug RCU usage or help work on the PROVE_RCU
1104 Say N if you are unsure.
1106 config PROVE_RCU_REPEATEDLY
1107 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1108 depends on PROVE_RCU
1111 By itself, PROVE_RCU will disable checking upon issuing the
1112 first warning (or "splat"). This feature prevents such
1113 disabling, allowing multiple RCU-lockdep warnings to be printed
1116 Say Y to allow multiple RCU-lockdep warnings per boot.
1118 Say N if you are unsure.
1120 config PROVE_RCU_DELAY
1121 bool "RCU debugging: preemptible RCU race provocation"
1122 depends on DEBUG_KERNEL && PREEMPT_RCU
1125 There is a class of races that involve an unlikely preemption
1126 of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
1127 been set to INT_MIN. This feature inserts a delay at that
1128 point to increase the probability of these races.
1130 Say Y to increase probability of preemption of __rcu_read_unlock().
1132 Say N if you are unsure.
1134 config SPARSE_RCU_POINTER
1135 bool "RCU debugging: sparse-based checks for pointer usage"
1138 This feature enables the __rcu sparse annotation for
1139 RCU-protected pointers. This annotation will cause sparse
1140 to flag any non-RCU used of annotated pointers. This can be
1141 helpful when debugging RCU usage. Please note that this feature
1142 is not intended to enforce code cleanliness; it is instead merely
1145 Say Y to make sparse flag questionable use of RCU-protected pointers
1147 Say N if you are unsure.
1153 config RCU_TORTURE_TEST
1154 tristate "torture tests for RCU"
1155 depends on DEBUG_KERNEL
1159 This option provides a kernel module that runs torture tests
1160 on the RCU infrastructure. The kernel module may be built
1161 after the fact on the running kernel to be tested, if desired.
1163 Say Y here if you want RCU torture tests to be built into
1165 Say M if you want the RCU torture tests to build as a module.
1166 Say N if you are unsure.
1168 config RCU_TORTURE_TEST_RUNNABLE
1169 bool "torture tests for RCU runnable by default"
1170 depends on RCU_TORTURE_TEST = y
1173 This option provides a way to build the RCU torture tests
1174 directly into the kernel without them starting up at boot
1175 time. You can use /proc/sys/kernel/rcutorture_runnable
1176 to manually override this setting. This /proc file is
1177 available only when the RCU torture tests have been built
1180 Say Y here if you want the RCU torture tests to start during
1181 boot (you probably don't).
1182 Say N here if you want the RCU torture tests to start only
1183 after being manually enabled via /proc.
1185 config RCU_CPU_STALL_TIMEOUT
1186 int "RCU CPU stall timeout in seconds"
1187 depends on RCU_STALL_COMMON
1191 If a given RCU grace period extends more than the specified
1192 number of seconds, a CPU stall warning is printed. If the
1193 RCU grace period persists, additional CPU stall warnings are
1194 printed at more widely spaced intervals.
1196 config RCU_CPU_STALL_VERBOSE
1197 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
1198 depends on TREE_PREEMPT_RCU
1201 This option causes RCU to printk detailed per-task information
1202 for any tasks that are stalling the current RCU grace period.
1204 Say N if you are unsure.
1206 Say Y if you want to enable such checks.
1208 config RCU_CPU_STALL_INFO
1209 bool "Print additional diagnostics on RCU CPU stall"
1210 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1213 For each stalled CPU that is aware of the current RCU grace
1214 period, print out additional per-CPU diagnostic information
1215 regarding scheduling-clock ticks, idle state, and,
1216 for RCU_FAST_NO_HZ kernels, idle-entry state.
1218 Say N if you are unsure.
1220 Say Y if you want to enable such diagnostics.
1223 bool "Enable tracing for RCU"
1224 depends on DEBUG_KERNEL
1227 This option provides tracing in RCU which presents stats
1228 in debugfs for debugging RCU implementation.
1230 Say Y here if you want to enable RCU tracing
1231 Say N if you are unsure.
1233 endmenu # "RCU Debugging"
1235 config DEBUG_BLOCK_EXT_DEVT
1236 bool "Force extended block device numbers and spread them"
1237 depends on DEBUG_KERNEL
1241 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1242 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1243 YOU ARE DOING. Distros, please enable this and fix whatever
1246 Conventionally, block device numbers are allocated from
1247 predetermined contiguous area. However, extended block area
1248 may introduce non-contiguous block device numbers. This
1249 option forces most block device numbers to be allocated from
1250 the extended space and spreads them to discover kernel or
1251 userland code paths which assume predetermined contiguous
1252 device number allocation.
1254 Note that turning on this debug option shuffles all the
1255 device numbers for all IDE and SCSI devices including libata
1256 ones, so root partition specified using device number
1257 directly (via rdev or root=MAJ:MIN) won't work anymore.
1258 Textual device names (root=/dev/sdXn) will continue to work.
1260 Say N if you are unsure.
1262 config NOTIFIER_ERROR_INJECTION
1263 tristate "Notifier error injection"
1264 depends on DEBUG_KERNEL
1267 This option provides the ability to inject artificial errors to
1268 specified notifier chain callbacks. It is useful to test the error
1269 handling of notifier call chain failures.
1273 config CPU_NOTIFIER_ERROR_INJECT
1274 tristate "CPU notifier error injection module"
1275 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1277 This option provides a kernel module that can be used to test
1278 the error handling of the cpu notifiers by injecting artificial
1279 errors to CPU notifier chain callbacks. It is controlled through
1280 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1282 If the notifier call chain should be failed with some events
1283 notified, write the error code to "actions/<notifier event>/error".
1285 Example: Inject CPU offline error (-1 == -EPERM)
1287 # cd /sys/kernel/debug/notifier-error-inject/cpu
1288 # echo -1 > actions/CPU_DOWN_PREPARE/error
1289 # echo 0 > /sys/devices/system/cpu/cpu1/online
1290 bash: echo: write error: Operation not permitted
1292 To compile this code as a module, choose M here: the module will
1293 be called cpu-notifier-error-inject.
1297 config PM_NOTIFIER_ERROR_INJECT
1298 tristate "PM notifier error injection module"
1299 depends on PM && NOTIFIER_ERROR_INJECTION
1300 default m if PM_DEBUG
1302 This option provides the ability to inject artificial errors to
1303 PM notifier chain callbacks. It is controlled through debugfs
1304 interface /sys/kernel/debug/notifier-error-inject/pm
1306 If the notifier call chain should be failed with some events
1307 notified, write the error code to "actions/<notifier event>/error".
1309 Example: Inject PM suspend error (-12 = -ENOMEM)
1311 # cd /sys/kernel/debug/notifier-error-inject/pm/
1312 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1313 # echo mem > /sys/power/state
1314 bash: echo: write error: Cannot allocate memory
1316 To compile this code as a module, choose M here: the module will
1317 be called pm-notifier-error-inject.
1321 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1322 tristate "OF reconfig notifier error injection module"
1323 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1325 This option provides the ability to inject artificial errors to
1326 OF reconfig notifier chain callbacks. It is controlled
1327 through debugfs interface under
1328 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1330 If the notifier call chain should be failed with some events
1331 notified, write the error code to "actions/<notifier event>/error".
1333 To compile this code as a module, choose M here: the module will
1334 be called of-reconfig-notifier-error-inject.
1338 config FAULT_INJECTION
1339 bool "Fault-injection framework"
1340 depends on DEBUG_KERNEL
1342 Provide fault-injection framework.
1343 For more details, see Documentation/fault-injection/.
1346 bool "Fault-injection capability for kmalloc"
1347 depends on FAULT_INJECTION
1348 depends on SLAB || SLUB
1350 Provide fault-injection capability for kmalloc.
1352 config FAIL_PAGE_ALLOC
1353 bool "Fault-injection capabilitiy for alloc_pages()"
1354 depends on FAULT_INJECTION
1356 Provide fault-injection capability for alloc_pages().
1358 config FAIL_MAKE_REQUEST
1359 bool "Fault-injection capability for disk IO"
1360 depends on FAULT_INJECTION && BLOCK
1362 Provide fault-injection capability for disk IO.
1364 config FAIL_IO_TIMEOUT
1365 bool "Fault-injection capability for faking disk interrupts"
1366 depends on FAULT_INJECTION && BLOCK
1368 Provide fault-injection capability on end IO handling. This
1369 will make the block layer "forget" an interrupt as configured,
1370 thus exercising the error handling.
1372 Only works with drivers that use the generic timeout handling,
1373 for others it wont do anything.
1375 config FAIL_MMC_REQUEST
1376 bool "Fault-injection capability for MMC IO"
1378 depends on FAULT_INJECTION && MMC
1380 Provide fault-injection capability for MMC IO.
1381 This will make the mmc core return data errors. This is
1382 useful to test the error handling in the mmc block device
1383 and to test how the mmc host driver handles retries from
1386 config FAULT_INJECTION_DEBUG_FS
1387 bool "Debugfs entries for fault-injection capabilities"
1388 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1390 Enable configuration of fault-injection capabilities via debugfs.
1392 config FAULT_INJECTION_STACKTRACE_FILTER
1393 bool "stacktrace filter for fault-injection capabilities"
1394 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1397 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1399 Provide stacktrace filter for fault-injection capabilities
1402 bool "Latency measuring infrastructure"
1403 depends on HAVE_LATENCYTOP_SUPPORT
1404 depends on DEBUG_KERNEL
1405 depends on STACKTRACE_SUPPORT
1407 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1414 Enable this option if you want to use the LatencyTOP tool
1415 to find out which userspace is blocking on what kernel operations.
1417 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1420 config DEBUG_STRICT_USER_COPY_CHECKS
1421 bool "Strict user copy size checks"
1422 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1423 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1425 Enabling this option turns a certain set of sanity checks for user
1426 copy operations into compile time failures.
1428 The copy_from_user() etc checks are there to help test if there
1429 are sufficient security checks on the length argument of
1430 the copy operation, by having gcc prove that the argument is
1435 source kernel/trace/Kconfig
1437 menu "Runtime Testing"
1440 tristate "Linux Kernel Dump Test Tool Module"
1445 This module enables testing of the different dumping mechanisms by
1446 inducing system failures at predefined crash points.
1447 If you don't need it: say N
1448 Choose M here to compile this code as a module. The module will be
1451 Documentation on how to use the module can be found in
1452 Documentation/fault-injection/provoke-crashes.txt
1454 config TEST_LIST_SORT
1455 bool "Linked list sorting test"
1456 depends on DEBUG_KERNEL
1458 Enable this to turn on 'list_sort()' function test. This test is
1459 executed only once during system boot, so affects only boot time.
1463 config KPROBES_SANITY_TEST
1464 bool "Kprobes sanity tests"
1465 depends on DEBUG_KERNEL
1469 This option provides for testing basic kprobes functionality on
1470 boot. A sample kprobe, jprobe and kretprobe are inserted and
1471 verified for functionality.
1473 Say N if you are unsure.
1475 config BACKTRACE_SELF_TEST
1476 tristate "Self test for the backtrace code"
1477 depends on DEBUG_KERNEL
1480 This option provides a kernel module that can be used to test
1481 the kernel stack backtrace code. This option is not useful
1482 for distributions or general kernels, but only for kernel
1483 developers working on architecture code.
1485 Note that if you want to also test saved backtraces, you will
1486 have to enable STACKTRACE as well.
1488 Say N if you are unsure.
1491 tristate "Red-Black tree test"
1492 depends on DEBUG_KERNEL
1494 A benchmark measuring the performance of the rbtree library.
1495 Also includes rbtree invariant checks.
1497 config INTERVAL_TREE_TEST
1498 tristate "Interval tree test"
1499 depends on m && DEBUG_KERNEL
1501 A benchmark measuring the performance of the interval tree library
1504 tristate "Per cpu operations test"
1505 depends on m && DEBUG_KERNEL
1507 Enable this option to build test module which validates per-cpu
1512 config ATOMIC64_SELFTEST
1513 bool "Perform an atomic64_t self-test at boot"
1515 Enable this option to test the atomic64_t functions at boot.
1519 config ASYNC_RAID6_TEST
1520 tristate "Self test for hardware accelerated raid6 recovery"
1521 depends on ASYNC_RAID6_RECOV
1524 This is a one-shot self test that permutes through the
1525 recovery of all the possible two disk failure scenarios for a
1526 N-disk array. Recovery is performed with the asynchronous
1527 raid6 recovery routines, and will optionally use an offload
1528 engine if one is available.
1532 config TEST_STRING_HELPERS
1533 tristate "Test functions located in the string_helpers module at runtime"
1536 tristate "Test kstrto*() family of functions at runtime"
1538 endmenu # runtime tests
1540 config PROVIDE_OHCI1394_DMA_INIT
1541 bool "Remote debugging over FireWire early on boot"
1542 depends on PCI && X86
1544 If you want to debug problems which hang or crash the kernel early
1545 on boot and the crashing machine has a FireWire port, you can use
1546 this feature to remotely access the memory of the crashed machine
1547 over FireWire. This employs remote DMA as part of the OHCI1394
1548 specification which is now the standard for FireWire controllers.
1550 With remote DMA, you can monitor the printk buffer remotely using
1551 firescope and access all memory below 4GB using fireproxy from gdb.
1552 Even controlling a kernel debugger is possible using remote DMA.
1556 If ohci1394_dma=early is used as boot parameter, it will initialize
1557 all OHCI1394 controllers which are found in the PCI config space.
1559 As all changes to the FireWire bus such as enabling and disabling
1560 devices cause a bus reset and thereby disable remote DMA for all
1561 devices, be sure to have the cable plugged and FireWire enabled on
1562 the debugging host before booting the debug target for debugging.
1564 This code (~1k) is freed after boot. By then, the firewire stack
1565 in charge of the OHCI-1394 controllers should be used instead.
1567 See Documentation/debugging-via-ohci1394.txt for more information.
1570 bool "Build targets in Documentation/ tree"
1571 depends on HEADERS_CHECK
1573 This option attempts to build objects from the source files in the
1574 kernel Documentation/ tree.
1576 Say N if you are unsure.
1578 config DMA_API_DEBUG
1579 bool "Enable debugging of DMA-API usage"
1580 depends on HAVE_DMA_API_DEBUG
1582 Enable this option to debug the use of the DMA API by device drivers.
1583 With this option you will be able to detect common bugs in device
1584 drivers like double-freeing of DMA mappings or freeing mappings that
1585 were never allocated.
1587 This also attempts to catch cases where a page owned by DMA is
1588 accessed by the cpu in a way that could cause data corruption. For
1589 example, this enables cow_user_page() to check that the source page is
1592 This option causes a performance degradation. Use only if you want to
1593 debug device drivers and dma interactions.
1598 tristate "Test module loading with 'hello world' module"
1602 This builds the "test_module" module that emits "Hello, world"
1603 on printk when loaded. It is designed to be used for basic
1604 evaluation of the module loading subsystem (for example when
1605 validating module verification). It lacks any extra dependencies,
1606 and will not normally be loaded by the system unless explicitly
1611 config TEST_USER_COPY
1612 tristate "Test user/kernel boundary protections"
1616 This builds the "test_user_copy" module that runs sanity checks
1617 on the copy_to/from_user infrastructure, making sure basic
1618 user/kernel boundary testing is working. If it fails to load,
1619 a regression has been detected in the user/kernel memory boundary
1624 source "samples/Kconfig"
1626 source "lib/Kconfig.kgdb"