| blob | 4e35a5d767ed2f50c69df7dbdbcf0e3d9885777f |
1 menu "printk and dmesg options"
3 config PRINTK_TIME
4 bool "Show timing information on printks"
5 depends on PRINTK
6 help
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)"
20 range 1 7
21 default "4"
22 help
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
27 priority.
29 config BOOT_PRINTK_DELAY
30 bool "Delay each boot printk message by N milliseconds"
31 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
32 help
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,
36 using "boot_delay=N".
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.
47 config DYNAMIC_DEBUG
48 bool "Enable dynamic printk() support"
49 default n
50 depends on PRINTK
51 depends on DEBUG_FS
52 help
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.
66 Usage:
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
84 From a live system:
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"
92 Example usage:
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"
120 config DEBUG_INFO
121 bool "Compile the kernel with debug info"
122 depends on DEBUG_KERNEL && !COMPILE_TEST
123 help
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.
131 If unsure, say N.
133 config DEBUG_INFO_REDUCED
134 bool "Reduce debugging information"
135 depends on DEBUG_INFO
136 help
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
149 help
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
164 help
165 Generate dwarf4 debug info. This requires recent versions
166 of gcc and gdb. It makes the debug information larger.
167 But it significantly improves the success of resolving
168 variables in gdb on optimized code.
170 config ENABLE_WARN_DEPRECATED
171 bool "Enable __deprecated logic"
172 default y
173 help
174 Enable the __deprecated logic in the kernel build.
175 Disable this to suppress the "warning: 'foo' is deprecated
176 (declared at kernel/power/somefile.c:1234)" messages.
178 config ENABLE_MUST_CHECK
179 bool "Enable __must_check logic"
180 default y
181 help
182 Enable the __must_check logic in the kernel build. Disable this to
183 suppress the "warning: ignoring return value of 'foo', declared with
184 attribute warn_unused_result" messages.
186 config FRAME_WARN
187 int "Warn for stack frames larger than (needs gcc 4.4)"
188 range 0 8192
189 default 1024 if !64BIT
190 default 2048 if 64BIT
191 help
192 Tell gcc to warn at build time for stack frames larger than this.
193 Setting this too low will cause a lot of warnings.
194 Setting it to 0 disables the warning.
195 Requires gcc 4.4
197 config STRIP_ASM_SYMS
198 bool "Strip assembler-generated symbols during link"
199 default n
200 help
201 Strip internal assembler-generated symbols during a link (symbols
202 that look like '.Lxxx') so they don't pollute the output of
203 get_wchan() and suchlike.
205 config READABLE_ASM
206 bool "Generate readable assembler code"
207 depends on DEBUG_KERNEL
208 help
209 Disable some compiler optimizations that tend to generate human unreadable
210 assembler output. This may make the kernel slightly slower, but it helps
211 to keep kernel developers who have to stare a lot at assembler listings
212 sane.
214 config UNUSED_SYMBOLS
215 bool "Enable unused/obsolete exported symbols"
216 default y if X86
217 help
218 Unused but exported symbols make the kernel needlessly bigger. For
219 that reason most of these unused exports will soon be removed. This
220 option is provided temporarily to provide a transition period in case
221 some external kernel module needs one of these symbols anyway. If you
222 encounter such a case in your module, consider if you are actually
223 using the right API. (rationale: since nobody in the kernel is using
224 this in a module, there is a pretty good chance it's actually the
225 wrong interface to use). If you really need the symbol, please send a
226 mail to the linux kernel mailing list mentioning the symbol and why
227 you really need it, and what the merge plan to the mainline kernel for
228 your module is.
230 config DEBUG_FS
231 bool "Debug Filesystem"
232 help
233 debugfs is a virtual file system that kernel developers use to put
234 debugging files into. Enable this option to be able to read and
235 write to these files.
237 For detailed documentation on the debugfs API, see
238 Documentation/DocBook/filesystems.
240 If unsure, say N.
242 config HEADERS_CHECK
243 bool "Run 'make headers_check' when building vmlinux"
244 depends on !UML
245 help
246 This option will extract the user-visible kernel headers whenever
247 building the kernel, and will run basic sanity checks on them to
248 ensure that exported files do not attempt to include files which
249 were not exported, etc.
251 If you're making modifications to header files which are
252 relevant for userspace, say 'Y', and check the headers
253 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
254 your build tree), to make sure they're suitable.
256 config DEBUG_SECTION_MISMATCH
257 bool "Enable full Section mismatch analysis"
258 help
259 The section mismatch analysis checks if there are illegal
260 references from one section to another section.
261 During linktime or runtime, some sections are dropped;
262 any use of code/data previously in these sections would
263 most likely result in an oops.
264 In the code, functions and variables are annotated with
265 __init,, etc. (see the full list in include/linux/init.h),
266 which results in the code/data being placed in specific sections.
267 The section mismatch analysis is always performed after a full
268 kernel build, and enabling this option causes the following
269 additional steps to occur:
270 - Add the option -fno-inline-functions-called-once to gcc commands.
271 When inlining a function annotated with __init in a non-init
272 function, we would lose the section information and thus
273 the analysis would not catch the illegal reference.
274 This option tells gcc to inline less (but it does result in
275 a larger kernel).
276 - Run the section mismatch analysis for each module/built-in.o file.
277 When we run the section mismatch analysis on vmlinux.o, we
278 lose valueble information about where the mismatch was
279 introduced.
280 Running the analysis for each module/built-in.o file
281 tells where the mismatch happens much closer to the
282 source. The drawback is that the same mismatch is
283 reported at least twice.
284 - Enable verbose reporting from modpost in order to help resolve
285 the section mismatches that are reported.
287 #
288 # Select this config option from the architecture Kconfig, if it
289 # is preferred to always offer frame pointers as a config
290 # option on the architecture (regardless of KERNEL_DEBUG):
291 #
292 config ARCH_WANT_FRAME_POINTERS
293 bool
294 help
296 config FRAME_POINTER
297 bool "Compile the kernel with frame pointers"
298 depends on DEBUG_KERNEL && \
299 (CRIS || M68K || FRV || UML || \
300 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
301 ARCH_WANT_FRAME_POINTERS
302 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
303 help
304 If you say Y here the resulting kernel image will be slightly
305 larger and slower, but it gives very useful debugging information
306 in case of kernel bugs. (precise oopses/stacktraces/warnings)
308 config DEBUG_FORCE_WEAK_PER_CPU
309 bool "Force weak per-cpu definitions"
310 depends on DEBUG_KERNEL
311 help
312 s390 and alpha require percpu variables in modules to be
313 defined weak to work around addressing range issue which
314 puts the following two restrictions on percpu variable
315 definitions.
317 1. percpu symbols must be unique whether static or not
318 2. percpu variables can't be defined inside a function
320 To ensure that generic code follows the above rules, this
321 option forces all percpu variables to be defined as weak.
323 endmenu # "Compiler options"
325 config MAGIC_SYSRQ
326 bool "Magic SysRq key"
327 depends on !UML
328 help
329 If you say Y here, you will have some control over the system even
330 if the system crashes for example during kernel debugging (e.g., you
331 will be able to flush the buffer cache to disk, reboot the system
332 immediately or dump some status information). This is accomplished
333 by pressing various keys while holding SysRq (Alt+PrintScreen). It
334 also works on a serial console (on PC hardware at least), if you
335 send a BREAK and then within 5 seconds a command keypress. The
336 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
337 unless you really know what this hack does.
339 config MAGIC_SYSRQ_DEFAULT_ENABLE
340 hex "Enable magic SysRq key functions by default"
341 depends on MAGIC_SYSRQ
342 default 0x1
343 help
344 Specifies which SysRq key functions are enabled by default.
345 This may be set to 1 or 0 to enable or disable them all, or
346 to a bitmask as described in Documentation/sysrq.txt.
348 config DEBUG_KERNEL
349 bool "Kernel debugging"
350 help
351 Say Y here if you are developing drivers or trying to debug and
352 identify kernel problems.
354 menu "Memory Debugging"
356 source mm/Kconfig.debug
358 config DEBUG_OBJECTS
359 bool "Debug object operations"
360 depends on DEBUG_KERNEL
361 help
362 If you say Y here, additional code will be inserted into the
363 kernel to track the life time of various objects and validate
364 the operations on those objects.
366 config DEBUG_OBJECTS_SELFTEST
367 bool "Debug objects selftest"
368 depends on DEBUG_OBJECTS
369 help
370 This enables the selftest of the object debug code.
372 config DEBUG_OBJECTS_FREE
373 bool "Debug objects in freed memory"
374 depends on DEBUG_OBJECTS
375 help
376 This enables checks whether a k/v free operation frees an area
377 which contains an object which has not been deactivated
378 properly. This can make kmalloc/kfree-intensive workloads
379 much slower.
381 config DEBUG_OBJECTS_TIMERS
382 bool "Debug timer objects"
383 depends on DEBUG_OBJECTS
384 help
385 If you say Y here, additional code will be inserted into the
386 timer routines to track the life time of timer objects and
387 validate the timer operations.
389 config DEBUG_OBJECTS_WORK
390 bool "Debug work objects"
391 depends on DEBUG_OBJECTS
392 help
393 If you say Y here, additional code will be inserted into the
394 work queue routines to track the life time of work objects and
395 validate the work operations.
397 config DEBUG_OBJECTS_RCU_HEAD
398 bool "Debug RCU callbacks objects"
399 depends on DEBUG_OBJECTS
400 help
401 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
403 config DEBUG_OBJECTS_PERCPU_COUNTER
404 bool "Debug percpu counter objects"
405 depends on DEBUG_OBJECTS
406 help
407 If you say Y here, additional code will be inserted into the
408 percpu counter routines to track the life time of percpu counter
409 objects and validate the percpu counter operations.
411 config DEBUG_OBJECTS_ENABLE_DEFAULT
412 int "debug_objects bootup default value (0-1)"
413 range 0 1
414 default "1"
415 depends on DEBUG_OBJECTS
416 help
417 Debug objects boot parameter default value
419 config DEBUG_SLAB
420 bool "Debug slab memory allocations"
421 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
422 help
423 Say Y here to have the kernel do limited verification on memory
424 allocation as well as poisoning memory on free to catch use of freed
425 memory. This can make kmalloc/kfree-intensive workloads much slower.
427 config DEBUG_SLAB_LEAK
428 bool "Memory leak debugging"
429 depends on DEBUG_SLAB
431 config SLUB_DEBUG_ON
432 bool "SLUB debugging on by default"
433 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
434 default n
435 help
436 Boot with debugging on by default. SLUB boots by default with
437 the runtime debug capabilities switched off. Enabling this is
438 equivalent to specifying the "slub_debug" parameter on boot.
439 There is no support for more fine grained debug control like
440 possible with slub_debug=xxx. SLUB debugging may be switched
441 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
442 "slub_debug=-".
444 config SLUB_STATS
445 default n
446 bool "Enable SLUB performance statistics"
447 depends on SLUB && SYSFS
448 help
449 SLUB statistics are useful to debug SLUBs allocation behavior in
450 order find ways to optimize the allocator. This should never be
451 enabled for production use since keeping statistics slows down
452 the allocator by a few percentage points. The slabinfo command
453 supports the determination of the most active slabs to figure
454 out which slabs are relevant to a particular load.
455 Try running: slabinfo -DA
457 config HAVE_DEBUG_KMEMLEAK
458 bool
460 config DEBUG_KMEMLEAK
461 bool "Kernel memory leak detector"
462 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
463 select DEBUG_FS
464 select STACKTRACE if STACKTRACE_SUPPORT
465 select KALLSYMS
466 select CRC32
467 help
468 Say Y here if you want to enable the memory leak
469 detector. The memory allocation/freeing is traced in a way
470 similar to the Boehm's conservative garbage collector, the
471 difference being that the orphan objects are not freed but
472 only shown in /sys/kernel/debug/kmemleak. Enabling this
473 feature will introduce an overhead to memory
474 allocations. See Documentation/kmemleak.txt for more
475 details.
477 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
478 of finding leaks due to the slab objects poisoning.
480 In order to access the kmemleak file, debugfs needs to be
481 mounted (usually at /sys/kernel/debug).
483 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
484 int "Maximum kmemleak early log entries"
485 depends on DEBUG_KMEMLEAK
486 range 200 40000
487 default 400
488 help
489 Kmemleak must track all the memory allocations to avoid
490 reporting false positives. Since memory may be allocated or
491 freed before kmemleak is initialised, an early log buffer is
492 used to store these actions. If kmemleak reports "early log
493 buffer exceeded", please increase this value.
495 config DEBUG_KMEMLEAK_TEST
496 tristate "Simple test for the kernel memory leak detector"
497 depends on DEBUG_KMEMLEAK && m
498 help
499 This option enables a module that explicitly leaks memory.
501 If unsure, say N.
503 config DEBUG_KMEMLEAK_DEFAULT_OFF
504 bool "Default kmemleak to off"
505 depends on DEBUG_KMEMLEAK
506 help
507 Say Y here to disable kmemleak by default. It can then be enabled
508 on the command line via kmemleak=on.
510 config DEBUG_STACK_USAGE
511 bool "Stack utilization instrumentation"
512 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
513 help
514 Enables the display of the minimum amount of free stack which each
515 task has ever had available in the sysrq-T and sysrq-P debug output.
517 This option will slow down process creation somewhat.
519 config DEBUG_VM
520 bool "Debug VM"
521 depends on DEBUG_KERNEL
522 help
523 Enable this to turn on extended checks in the virtual-memory system
524 that may impact performance.
526 If unsure, say N.
528 config DEBUG_VM_VMACACHE
529 bool "Debug VMA caching"
530 depends on DEBUG_VM
531 help
532 Enable this to turn on VMA caching debug information. Doing so
533 can cause significant overhead, so only enable it in non-production
534 environments.
536 If unsure, say N.
538 config DEBUG_VM_RB
539 bool "Debug VM red-black trees"
540 depends on DEBUG_VM
541 help
542 Enable VM red-black tree debugging information and extra validations.
544 If unsure, say N.
546 config DEBUG_VIRTUAL
547 bool "Debug VM translations"
548 depends on DEBUG_KERNEL && X86
549 help
550 Enable some costly sanity checks in virtual to page code. This can
551 catch mistakes with virt_to_page() and friends.
553 If unsure, say N.
555 config DEBUG_NOMMU_REGIONS
556 bool "Debug the global anon/private NOMMU mapping region tree"
557 depends on DEBUG_KERNEL && !MMU
558 help
559 This option causes the global tree of anonymous and private mapping
560 regions to be regularly checked for invalid topology.
562 config DEBUG_MEMORY_INIT
563 bool "Debug memory initialisation" if EXPERT
564 default !EXPERT
565 help
566 Enable this for additional checks during memory initialisation.
567 The sanity checks verify aspects of the VM such as the memory model
568 and other information provided by the architecture. Verbose
569 information will be printed at KERN_DEBUG loglevel depending
570 on the mminit_loglevel= command-line option.
572 If unsure, say Y
574 config MEMORY_NOTIFIER_ERROR_INJECT
575 tristate "Memory hotplug notifier error injection module"
576 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
577 help
578 This option provides the ability to inject artificial errors to
579 memory hotplug notifier chain callbacks. It is controlled through
580 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
582 If the notifier call chain should be failed with some events
583 notified, write the error code to "actions/<notifier event>/error".
585 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
587 # cd /sys/kernel/debug/notifier-error-inject/memory
588 # echo -12 > actions/MEM_GOING_OFFLINE/error
589 # echo offline > /sys/devices/system/memory/memoryXXX/state
590 bash: echo: write error: Cannot allocate memory
592 To compile this code as a module, choose M here: the module will
593 be called memory-notifier-error-inject.
595 If unsure, say N.
597 config DEBUG_PER_CPU_MAPS
598 bool "Debug access to per_cpu maps"
599 depends on DEBUG_KERNEL
600 depends on SMP
601 help
602 Say Y to verify that the per_cpu map being accessed has
603 been set up. This adds a fair amount of code to kernel memory
604 and decreases performance.
606 Say N if unsure.
608 config DEBUG_HIGHMEM
609 bool "Highmem debugging"
610 depends on DEBUG_KERNEL && HIGHMEM
611 help
612 This option enables additional error checking for high memory
613 systems. Disable for production systems.
615 config HAVE_DEBUG_STACKOVERFLOW
616 bool
618 config DEBUG_STACKOVERFLOW
619 bool "Check for stack overflows"
620 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
621 ---help---
622 Say Y here if you want to check for overflows of kernel, IRQ
623 and exception stacks (if your archicture uses them). This
624 option will show detailed messages if free stack space drops
625 below a certain limit.
627 These kinds of bugs usually occur when call-chains in the
628 kernel get too deep, especially when interrupts are
629 involved.
631 Use this in cases where you see apparently random memory
632 corruption, especially if it appears in 'struct thread_info'
634 If in doubt, say "N".
636 source "lib/Kconfig.kmemcheck"
638 endmenu # "Memory Debugging"
640 config DEBUG_SHIRQ
641 bool "Debug shared IRQ handlers"
642 depends on DEBUG_KERNEL
643 help
644 Enable this to generate a spurious interrupt as soon as a shared
645 interrupt handler is registered, and just before one is deregistered.
646 Drivers ought to be able to handle interrupts coming in at those
647 points; some don't and need to be caught.
649 menu "Debug Lockups and Hangs"
651 config LOCKUP_DETECTOR
652 bool "Detect Hard and Soft Lockups"
653 depends on DEBUG_KERNEL && !S390
654 help
655 Say Y here to enable the kernel to act as a watchdog to detect
656 hard and soft lockups.
658 Softlockups are bugs that cause the kernel to loop in kernel
659 mode for more than 20 seconds, without giving other tasks a
660 chance to run. The current stack trace is displayed upon
661 detection and the system will stay locked up.
663 Hardlockups are bugs that cause the CPU to loop in kernel mode
664 for more than 10 seconds, without letting other interrupts have a
665 chance to run. The current stack trace is displayed upon detection
666 and the system will stay locked up.
668 The overhead should be minimal. A periodic hrtimer runs to
669 generate interrupts and kick the watchdog task every 4 seconds.
670 An NMI is generated every 10 seconds or so to check for hardlockups.
672 The frequency of hrtimer and NMI events and the soft and hard lockup
673 thresholds can be controlled through the sysctl watchdog_thresh.
675 config HARDLOCKUP_DETECTOR
676 def_bool y
677 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
678 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
680 config BOOTPARAM_HARDLOCKUP_PANIC
681 bool "Panic (Reboot) On Hard Lockups"
682 depends on HARDLOCKUP_DETECTOR
683 help
684 Say Y here to enable the kernel to panic on "hard lockups",
685 which are bugs that cause the kernel to loop in kernel
686 mode with interrupts disabled for more than 10 seconds (configurable
687 using the watchdog_thresh sysctl).
689 Say N if unsure.
691 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
692 int
693 depends on HARDLOCKUP_DETECTOR
694 range 0 1
695 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
696 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
698 config BOOTPARAM_SOFTLOCKUP_PANIC
699 bool "Panic (Reboot) On Soft Lockups"
700 depends on LOCKUP_DETECTOR
701 help
702 Say Y here to enable the kernel to panic on "soft lockups",
703 which are bugs that cause the kernel to loop in kernel
704 mode for more than 20 seconds (configurable using the watchdog_thresh
705 sysctl), without giving other tasks a chance to run.
707 The panic can be used in combination with panic_timeout,
708 to cause the system to reboot automatically after a
709 lockup has been detected. This feature is useful for
710 high-availability systems that have uptime guarantees and
711 where a lockup must be resolved ASAP.
713 Say N if unsure.
715 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
716 int
717 depends on LOCKUP_DETECTOR
718 range 0 1
719 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
720 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
722 config DETECT_HUNG_TASK
723 bool "Detect Hung Tasks"
724 depends on DEBUG_KERNEL
725 default LOCKUP_DETECTOR
726 help
727 Say Y here to enable the kernel to detect "hung tasks",
728 which are bugs that cause the task to be stuck in
729 uninterruptible "D" state indefinitiley.
731 When a hung task is detected, the kernel will print the
732 current stack trace (which you should report), but the
733 task will stay in uninterruptible state. If lockdep is
734 enabled then all held locks will also be reported. This
735 feature has negligible overhead.
737 config DEFAULT_HUNG_TASK_TIMEOUT
738 int "Default timeout for hung task detection (in seconds)"
739 depends on DETECT_HUNG_TASK
740 default 120
741 help
742 This option controls the default timeout (in seconds) used
743 to determine when a task has become non-responsive and should
744 be considered hung.
746 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
747 sysctl or by writing a value to
748 /proc/sys/kernel/hung_task_timeout_secs.
750 A timeout of 0 disables the check. The default is two minutes.
751 Keeping the default should be fine in most cases.
753 config BOOTPARAM_HUNG_TASK_PANIC
754 bool "Panic (Reboot) On Hung Tasks"
755 depends on DETECT_HUNG_TASK
756 help
757 Say Y here to enable the kernel to panic on "hung tasks",
758 which are bugs that cause the kernel to leave a task stuck
759 in uninterruptible "D" state.
761 The panic can be used in combination with panic_timeout,
762 to cause the system to reboot automatically after a
763 hung task has been detected. This feature is useful for
764 high-availability systems that have uptime guarantees and
765 where a hung tasks must be resolved ASAP.
767 Say N if unsure.
769 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
770 int
771 depends on DETECT_HUNG_TASK
772 range 0 1
773 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
774 default 1 if BOOTPARAM_HUNG_TASK_PANIC
776 endmenu # "Debug lockups and hangs"
778 config PANIC_ON_OOPS
779 bool "Panic on Oops"
780 help
781 Say Y here to enable the kernel to panic when it oopses. This
782 has the same effect as setting oops=panic on the kernel command
783 line.
785 This feature is useful to ensure that the kernel does not do
786 anything erroneous after an oops which could result in data
787 corruption or other issues.
789 Say N if unsure.
791 config PANIC_ON_OOPS_VALUE
792 int
793 range 0 1
794 default 0 if !PANIC_ON_OOPS
795 default 1 if PANIC_ON_OOPS
797 config PANIC_TIMEOUT
798 int "panic timeout"
799 default 0
800 help
801 Set the timeout value (in seconds) until a reboot occurs when the
802 the kernel panics. If n = 0, then we wait forever. A timeout
803 value n > 0 will wait n seconds before rebooting, while a timeout
804 value n < 0 will reboot immediately.
806 config SCHED_DEBUG
807 bool "Collect scheduler debugging info"
808 depends on DEBUG_KERNEL && PROC_FS
809 default y
810 help
811 If you say Y here, the /proc/sched_debug file will be provided
812 that can help debug the scheduler. The runtime overhead of this
813 option is minimal.
815 config SCHEDSTATS
816 bool "Collect scheduler statistics"
817 depends on DEBUG_KERNEL && PROC_FS
818 help
819 If you say Y here, additional code will be inserted into the
820 scheduler and related routines to collect statistics about
821 scheduler behavior and provide them in /proc/schedstat. These
822 stats may be useful for both tuning and debugging the scheduler
823 If you aren't debugging the scheduler or trying to tune a specific
824 application, you can say N to avoid the very slight overhead
825 this adds.
827 config SCHED_STACK_END_CHECK
828 bool "Detect stack corruption on calls to schedule()"
829 depends on DEBUG_KERNEL
830 default n
831 help
832 This option checks for a stack overrun on calls to schedule().
833 If the stack end location is found to be over written always panic as
834 the content of the corrupted region can no longer be trusted.
835 This is to ensure no erroneous behaviour occurs which could result in
836 data corruption or a sporadic crash at a later stage once the region
837 is examined. The runtime overhead introduced is minimal.
839 config TIMER_STATS
840 bool "Collect kernel timers statistics"
841 depends on DEBUG_KERNEL && PROC_FS
842 help
843 If you say Y here, additional code will be inserted into the
844 timer routines to collect statistics about kernel timers being
845 reprogrammed. The statistics can be read from /proc/timer_stats.
846 The statistics collection is started by writing 1 to /proc/timer_stats,
847 writing 0 stops it. This feature is useful to collect information
848 about timer usage patterns in kernel and userspace. This feature
849 is lightweight if enabled in the kernel config but not activated
850 (it defaults to deactivated on bootup and will only be activated
851 if some application like powertop activates it explicitly).
853 config DEBUG_PREEMPT
854 bool "Debug preemptible kernel"
855 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
856 default y
857 help
858 If you say Y here then the kernel will use a debug variant of the
859 commonly used smp_processor_id() function and will print warnings
860 if kernel code uses it in a preemption-unsafe way. Also, the kernel
861 will detect preemption count underflows.
863 menu "Lock Debugging (spinlocks, mutexes, etc...)"
865 config DEBUG_RT_MUTEXES
866 bool "RT Mutex debugging, deadlock detection"
867 depends on DEBUG_KERNEL && RT_MUTEXES
868 help
869 This allows rt mutex semantics violations and rt mutex related
870 deadlocks (lockups) to be detected and reported automatically.
872 config RT_MUTEX_TESTER
873 bool "Built-in scriptable tester for rt-mutexes"
874 depends on DEBUG_KERNEL && RT_MUTEXES && BROKEN
875 help
876 This option enables a rt-mutex tester.
878 config DEBUG_SPINLOCK
879 bool "Spinlock and rw-lock debugging: basic checks"
880 depends on DEBUG_KERNEL
881 select UNINLINE_SPIN_UNLOCK
882 help
883 Say Y here and build SMP to catch missing spinlock initialization
884 and certain other kinds of spinlock errors commonly made. This is
885 best used in conjunction with the NMI watchdog so that spinlock
886 deadlocks are also debuggable.
888 config DEBUG_MUTEXES
889 bool "Mutex debugging: basic checks"
890 depends on DEBUG_KERNEL
891 help
892 This feature allows mutex semantics violations to be detected and
893 reported.
895 config DEBUG_WW_MUTEX_SLOWPATH
896 bool "Wait/wound mutex debugging: Slowpath testing"
897 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
898 select DEBUG_LOCK_ALLOC
899 select DEBUG_SPINLOCK
900 select DEBUG_MUTEXES
901 help
902 This feature enables slowpath testing for w/w mutex users by
903 injecting additional -EDEADLK wound/backoff cases. Together with
904 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
905 will test all possible w/w mutex interface abuse with the
906 exception of simply not acquiring all the required locks.
907 Note that this feature can introduce significant overhead, so
908 it really should not be enabled in a production or distro kernel,
909 even a debug kernel. If you are a driver writer, enable it. If
910 you are a distro, do not.
912 config DEBUG_LOCK_ALLOC
913 bool "Lock debugging: detect incorrect freeing of live locks"
914 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
915 select DEBUG_SPINLOCK
916 select DEBUG_MUTEXES
917 select LOCKDEP
918 help
919 This feature will check whether any held lock (spinlock, rwlock,
920 mutex or rwsem) is incorrectly freed by the kernel, via any of the
921 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
922 vfree(), etc.), whether a live lock is incorrectly reinitialized via
923 spin_lock_init()/mutex_init()/etc., or whether there is any lock
924 held during task exit.
926 config PROVE_LOCKING
927 bool "Lock debugging: prove locking correctness"
928 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
929 select LOCKDEP
930 select DEBUG_SPINLOCK
931 select DEBUG_MUTEXES
932 select DEBUG_LOCK_ALLOC
933 select TRACE_IRQFLAGS
934 default n
935 help
936 This feature enables the kernel to prove that all locking
937 that occurs in the kernel runtime is mathematically
938 correct: that under no circumstance could an arbitrary (and
939 not yet triggered) combination of observed locking
940 sequences (on an arbitrary number of CPUs, running an
941 arbitrary number of tasks and interrupt contexts) cause a
942 deadlock.
944 In short, this feature enables the kernel to report locking
945 related deadlocks before they actually occur.
947 The proof does not depend on how hard and complex a
948 deadlock scenario would be to trigger: how many
949 participant CPUs, tasks and irq-contexts would be needed
950 for it to trigger. The proof also does not depend on
951 timing: if a race and a resulting deadlock is possible
952 theoretically (no matter how unlikely the race scenario
953 is), it will be proven so and will immediately be
954 reported by the kernel (once the event is observed that
955 makes the deadlock theoretically possible).
957 If a deadlock is impossible (i.e. the locking rules, as
958 observed by the kernel, are mathematically correct), the
959 kernel reports nothing.
961 NOTE: this feature can also be enabled for rwlocks, mutexes
962 and rwsems - in which case all dependencies between these
963 different locking variants are observed and mapped too, and
964 the proof of observed correctness is also maintained for an
965 arbitrary combination of these separate locking variants.
967 For more details, see Documentation/locking/lockdep-design.txt.
969 config LOCKDEP
970 bool
971 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
972 select STACKTRACE
973 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
974 select KALLSYMS
975 select KALLSYMS_ALL
977 config LOCK_STAT
978 bool "Lock usage statistics"
979 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
980 select LOCKDEP
981 select DEBUG_SPINLOCK
982 select DEBUG_MUTEXES
983 select DEBUG_LOCK_ALLOC
984 default n
985 help
986 This feature enables tracking lock contention points
988 For more details, see Documentation/locking/lockstat.txt
990 This also enables lock events required by "perf lock",
991 subcommand of perf.
992 If you want to use "perf lock", you also need to turn on
993 CONFIG_EVENT_TRACING.
995 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
996 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
998 config DEBUG_LOCKDEP
999 bool "Lock dependency engine debugging"
1000 depends on DEBUG_KERNEL && LOCKDEP
1001 help
1002 If you say Y here, the lock dependency engine will do
1003 additional runtime checks to debug itself, at the price
1004 of more runtime overhead.
1006 config DEBUG_ATOMIC_SLEEP
1007 bool "Sleep inside atomic section checking"
1008 select PREEMPT_COUNT
1009 depends on DEBUG_KERNEL
1010 help
1011 If you say Y here, various routines which may sleep will become very
1012 noisy if they are called inside atomic sections: when a spinlock is
1013 held, inside an rcu read side critical section, inside preempt disabled
1014 sections, inside an interrupt, etc...
1016 config DEBUG_LOCKING_API_SELFTESTS
1017 bool "Locking API boot-time self-tests"
1018 depends on DEBUG_KERNEL
1019 help
1020 Say Y here if you want the kernel to run a short self-test during
1021 bootup. The self-test checks whether common types of locking bugs
1022 are detected by debugging mechanisms or not. (if you disable
1023 lock debugging then those bugs wont be detected of course.)
1024 The following locking APIs are covered: spinlocks, rwlocks,
1025 mutexes and rwsems.
1027 config LOCK_TORTURE_TEST
1028 tristate "torture tests for locking"
1029 depends on DEBUG_KERNEL
1030 select TORTURE_TEST
1031 default n
1032 help
1033 This option provides a kernel module that runs torture tests
1034 on kernel locking primitives. The kernel module may be built
1035 after the fact on the running kernel to be tested, if desired.
1037 Say Y here if you want kernel locking-primitive torture tests
1038 to be built into the kernel.
1039 Say M if you want these torture tests to build as a module.
1040 Say N if you are unsure.
1042 endmenu # lock debugging
1044 config TRACE_IRQFLAGS
1045 bool
1046 help
1047 Enables hooks to interrupt enabling and disabling for
1048 either tracing or lock debugging.
1050 config STACKTRACE
1051 bool "Stack backtrace support"
1052 depends on STACKTRACE_SUPPORT
1053 help
1054 This option causes the kernel to create a /proc/pid/stack for
1055 every process, showing its current stack trace.
1056 It is also used by various kernel debugging features that require
1057 stack trace generation.
1059 config DEBUG_KOBJECT
1060 bool "kobject debugging"
1061 depends on DEBUG_KERNEL
1062 help
1063 If you say Y here, some extra kobject debugging messages will be sent
1064 to the syslog.
1066 config DEBUG_KOBJECT_RELEASE
1067 bool "kobject release debugging"
1068 depends on DEBUG_OBJECTS_TIMERS
1069 help
1070 kobjects are reference counted objects. This means that their
1071 last reference count put is not predictable, and the kobject can
1072 live on past the point at which a driver decides to drop it's
1073 initial reference to the kobject gained on allocation. An
1074 example of this would be a struct device which has just been
1075 unregistered.
1077 However, some buggy drivers assume that after such an operation,
1078 the memory backing the kobject can be immediately freed. This
1079 goes completely against the principles of a refcounted object.
1081 If you say Y here, the kernel will delay the release of kobjects
1082 on the last reference count to improve the visibility of this
1083 kind of kobject release bug.
1085 config HAVE_DEBUG_BUGVERBOSE
1086 bool
1088 config DEBUG_BUGVERBOSE
1089 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1090 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1091 default y
1092 help
1093 Say Y here to make BUG() panics output the file name and line number
1094 of the BUG call as well as the EIP and oops trace. This aids
1095 debugging but costs about 70-100K of memory.
1097 config DEBUG_LIST
1098 bool "Debug linked list manipulation"
1099 depends on DEBUG_KERNEL
1100 help
1101 Enable this to turn on extended checks in the linked-list
1102 walking routines.
1104 If unsure, say N.
1106 config DEBUG_PI_LIST
1107 bool "Debug priority linked list manipulation"
1108 depends on DEBUG_KERNEL
1109 help
1110 Enable this to turn on extended checks in the priority-ordered
1111 linked-list (plist) walking routines. This checks the entire
1112 list multiple times during each manipulation.
1114 If unsure, say N.
1116 config DEBUG_SG
1117 bool "Debug SG table operations"
1118 depends on DEBUG_KERNEL
1119 help
1120 Enable this to turn on checks on scatter-gather tables. This can
1121 help find problems with drivers that do not properly initialize
1122 their sg tables.
1124 If unsure, say N.
1126 config DEBUG_NOTIFIERS
1127 bool "Debug notifier call chains"
1128 depends on DEBUG_KERNEL
1129 help
1130 Enable this to turn on sanity checking for notifier call chains.
1131 This is most useful for kernel developers to make sure that
1132 modules properly unregister themselves from notifier chains.
1133 This is a relatively cheap check but if you care about maximum
1134 performance, say N.
1136 config DEBUG_CREDENTIALS
1137 bool "Debug credential management"
1138 depends on DEBUG_KERNEL
1139 help
1140 Enable this to turn on some debug checking for credential
1141 management. The additional code keeps track of the number of
1142 pointers from task_structs to any given cred struct, and checks to
1143 see that this number never exceeds the usage count of the cred
1144 struct.
1146 Furthermore, if SELinux is enabled, this also checks that the
1147 security pointer in the cred struct is never seen to be invalid.
1149 If unsure, say N.
1151 menu "RCU Debugging"
1153 config PROVE_RCU
1154 bool "RCU debugging: prove RCU correctness"
1155 depends on PROVE_LOCKING
1156 default n
1157 help
1158 This feature enables lockdep extensions that check for correct
1159 use of RCU APIs. This is currently under development. Say Y
1160 if you want to debug RCU usage or help work on the PROVE_RCU
1161 feature.
1163 Say N if you are unsure.
1165 config PROVE_RCU_REPEATEDLY
1166 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1167 depends on PROVE_RCU
1168 default n
1169 help
1170 By itself, PROVE_RCU will disable checking upon issuing the
1171 first warning (or "splat"). This feature prevents such
1172 disabling, allowing multiple RCU-lockdep warnings to be printed
1173 on a single reboot.
1175 Say Y to allow multiple RCU-lockdep warnings per boot.
1177 Say N if you are unsure.
1179 config SPARSE_RCU_POINTER
1180 bool "RCU debugging: sparse-based checks for pointer usage"
1181 default n
1182 help
1183 This feature enables the __rcu sparse annotation for
1184 RCU-protected pointers. This annotation will cause sparse
1185 to flag any non-RCU used of annotated pointers. This can be
1186 helpful when debugging RCU usage. Please note that this feature
1187 is not intended to enforce code cleanliness; it is instead merely
1188 a debugging aid.
1190 Say Y to make sparse flag questionable use of RCU-protected pointers
1192 Say N if you are unsure.
1194 config TORTURE_TEST
1195 tristate
1196 default n
1198 config RCU_TORTURE_TEST
1199 tristate "torture tests for RCU"
1200 depends on DEBUG_KERNEL
1201 select TORTURE_TEST
1202 default n
1203 help
1204 This option provides a kernel module that runs torture tests
1205 on the RCU infrastructure. The kernel module may be built
1206 after the fact on the running kernel to be tested, if desired.
1208 Say Y here if you want RCU torture tests to be built into
1209 the kernel.
1210 Say M if you want the RCU torture tests to build as a module.
1211 Say N if you are unsure.
1213 config RCU_TORTURE_TEST_RUNNABLE
1214 bool "torture tests for RCU runnable by default"
1215 depends on RCU_TORTURE_TEST = y
1216 default n
1217 help
1218 This option provides a way to build the RCU torture tests
1219 directly into the kernel without them starting up at boot
1220 time. You can use /proc/sys/kernel/rcutorture_runnable
1221 to manually override this setting. This /proc file is
1222 available only when the RCU torture tests have been built
1223 into the kernel.
1225 Say Y here if you want the RCU torture tests to start during
1226 boot (you probably don't).
1227 Say N here if you want the RCU torture tests to start only
1228 after being manually enabled via /proc.
1230 config RCU_CPU_STALL_TIMEOUT
1231 int "RCU CPU stall timeout in seconds"
1232 depends on RCU_STALL_COMMON
1233 range 3 300
1234 default 21
1235 help
1236 If a given RCU grace period extends more than the specified
1237 number of seconds, a CPU stall warning is printed. If the
1238 RCU grace period persists, additional CPU stall warnings are
1239 printed at more widely spaced intervals.
1241 config RCU_CPU_STALL_VERBOSE
1242 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
1243 depends on TREE_PREEMPT_RCU
1244 default y
1245 help
1246 This option causes RCU to printk detailed per-task information
1247 for any tasks that are stalling the current RCU grace period.
1249 Say N if you are unsure.
1251 Say Y if you want to enable such checks.
1253 config RCU_CPU_STALL_INFO
1254 bool "Print additional diagnostics on RCU CPU stall"
1255 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
1256 default n
1257 help
1258 For each stalled CPU that is aware of the current RCU grace
1259 period, print out additional per-CPU diagnostic information
1260 regarding scheduling-clock ticks, idle state, and,
1261 for RCU_FAST_NO_HZ kernels, idle-entry state.
1263 Say N if you are unsure.
1265 Say Y if you want to enable such diagnostics.
1267 config RCU_TRACE
1268 bool "Enable tracing for RCU"
1269 depends on DEBUG_KERNEL
1270 select TRACE_CLOCK
1271 help
1272 This option provides tracing in RCU which presents stats
1273 in debugfs for debugging RCU implementation.
1275 Say Y here if you want to enable RCU tracing
1276 Say N if you are unsure.
1278 endmenu # "RCU Debugging"
1280 config DEBUG_BLOCK_EXT_DEVT
1281 bool "Force extended block device numbers and spread them"
1282 depends on DEBUG_KERNEL
1283 depends on BLOCK
1284 default n
1285 help
1286 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1287 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1288 YOU ARE DOING. Distros, please enable this and fix whatever
1289 is broken.
1291 Conventionally, block device numbers are allocated from
1292 predetermined contiguous area. However, extended block area
1293 may introduce non-contiguous block device numbers. This
1294 option forces most block device numbers to be allocated from
1295 the extended space and spreads them to discover kernel or
1296 userland code paths which assume predetermined contiguous
1297 device number allocation.
1299 Note that turning on this debug option shuffles all the
1300 device numbers for all IDE and SCSI devices including libata
1301 ones, so root partition specified using device number
1302 directly (via rdev or root=MAJ:MIN) won't work anymore.
1303 Textual device names (root=/dev/sdXn) will continue to work.
1305 Say N if you are unsure.
1307 config NOTIFIER_ERROR_INJECTION
1308 tristate "Notifier error injection"
1309 depends on DEBUG_KERNEL
1310 select DEBUG_FS
1311 help
1312 This option provides the ability to inject artificial errors to
1313 specified notifier chain callbacks. It is useful to test the error
1314 handling of notifier call chain failures.
1316 Say N if unsure.
1318 config CPU_NOTIFIER_ERROR_INJECT
1319 tristate "CPU notifier error injection module"
1320 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1321 help
1322 This option provides a kernel module that can be used to test
1323 the error handling of the cpu notifiers by injecting artificial
1324 errors to CPU notifier chain callbacks. It is controlled through
1325 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1327 If the notifier call chain should be failed with some events
1328 notified, write the error code to "actions/<notifier event>/error".
1330 Example: Inject CPU offline error (-1 == -EPERM)
1332 # cd /sys/kernel/debug/notifier-error-inject/cpu
1333 # echo -1 > actions/CPU_DOWN_PREPARE/error
1334 # echo 0 > /sys/devices/system/cpu/cpu1/online
1335 bash: echo: write error: Operation not permitted
1337 To compile this code as a module, choose M here: the module will
1338 be called cpu-notifier-error-inject.
1340 If unsure, say N.
1342 config PM_NOTIFIER_ERROR_INJECT
1343 tristate "PM notifier error injection module"
1344 depends on PM && NOTIFIER_ERROR_INJECTION
1345 default m if PM_DEBUG
1346 help
1347 This option provides the ability to inject artificial errors to
1348 PM notifier chain callbacks. It is controlled through debugfs
1349 interface /sys/kernel/debug/notifier-error-inject/pm
1351 If the notifier call chain should be failed with some events
1352 notified, write the error code to "actions/<notifier event>/error".
1354 Example: Inject PM suspend error (-12 = -ENOMEM)
1356 # cd /sys/kernel/debug/notifier-error-inject/pm/
1357 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1358 # echo mem > /sys/power/state
1359 bash: echo: write error: Cannot allocate memory
1361 To compile this code as a module, choose M here: the module will
1362 be called pm-notifier-error-inject.
1364 If unsure, say N.
1366 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1367 tristate "OF reconfig notifier error injection module"
1368 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1369 help
1370 This option provides the ability to inject artificial errors to
1371 OF reconfig notifier chain callbacks. It is controlled
1372 through debugfs interface under
1373 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1375 If the notifier call chain should be failed with some events
1376 notified, write the error code to "actions/<notifier event>/error".
1378 To compile this code as a module, choose M here: the module will
1379 be called of-reconfig-notifier-error-inject.
1381 If unsure, say N.
1383 config FAULT_INJECTION
1384 bool "Fault-injection framework"
1385 depends on DEBUG_KERNEL
1386 help
1387 Provide fault-injection framework.
1388 For more details, see Documentation/fault-injection/.
1390 config FAILSLAB
1391 bool "Fault-injection capability for kmalloc"
1392 depends on FAULT_INJECTION
1393 depends on SLAB || SLUB
1394 help
1395 Provide fault-injection capability for kmalloc.
1397 config FAIL_PAGE_ALLOC
1398 bool "Fault-injection capabilitiy for alloc_pages()"
1399 depends on FAULT_INJECTION
1400 help
1401 Provide fault-injection capability for alloc_pages().
1403 config FAIL_MAKE_REQUEST
1404 bool "Fault-injection capability for disk IO"
1405 depends on FAULT_INJECTION && BLOCK
1406 help
1407 Provide fault-injection capability for disk IO.
1409 config FAIL_IO_TIMEOUT
1410 bool "Fault-injection capability for faking disk interrupts"
1411 depends on FAULT_INJECTION && BLOCK
1412 help
1413 Provide fault-injection capability on end IO handling. This
1414 will make the block layer "forget" an interrupt as configured,
1415 thus exercising the error handling.
1417 Only works with drivers that use the generic timeout handling,
1418 for others it wont do anything.
1420 config FAIL_MMC_REQUEST
1421 bool "Fault-injection capability for MMC IO"
1422 select DEBUG_FS
1423 depends on FAULT_INJECTION && MMC
1424 help
1425 Provide fault-injection capability for MMC IO.
1426 This will make the mmc core return data errors. This is
1427 useful to test the error handling in the mmc block device
1428 and to test how the mmc host driver handles retries from
1429 the block device.
1431 config FAULT_INJECTION_DEBUG_FS
1432 bool "Debugfs entries for fault-injection capabilities"
1433 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1434 help
1435 Enable configuration of fault-injection capabilities via debugfs.
1437 config FAULT_INJECTION_STACKTRACE_FILTER
1438 bool "stacktrace filter for fault-injection capabilities"
1439 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1440 depends on !X86_64
1441 select STACKTRACE
1442 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1443 help
1444 Provide stacktrace filter for fault-injection capabilities
1446 config LATENCYTOP
1447 bool "Latency measuring infrastructure"
1448 depends on HAVE_LATENCYTOP_SUPPORT
1449 depends on DEBUG_KERNEL
1450 depends on STACKTRACE_SUPPORT
1451 depends on PROC_FS
1452 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1453 select KALLSYMS
1454 select KALLSYMS_ALL
1455 select STACKTRACE
1456 select SCHEDSTATS
1457 select SCHED_DEBUG
1458 help
1459 Enable this option if you want to use the LatencyTOP tool
1460 to find out which userspace is blocking on what kernel operations.
1462 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1463 bool
1465 config DEBUG_STRICT_USER_COPY_CHECKS
1466 bool "Strict user copy size checks"
1467 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1468 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1469 help
1470 Enabling this option turns a certain set of sanity checks for user
1471 copy operations into compile time failures.
1473 The copy_from_user() etc checks are there to help test if there
1474 are sufficient security checks on the length argument of
1475 the copy operation, by having gcc prove that the argument is
1476 within bounds.
1478 If unsure, say N.
1480 source kernel/trace/Kconfig
1482 menu "Runtime Testing"
1484 config LKDTM
1485 tristate "Linux Kernel Dump Test Tool Module"
1486 depends on DEBUG_FS
1487 depends on BLOCK
1488 default n
1489 help
1490 This module enables testing of the different dumping mechanisms by
1491 inducing system failures at predefined crash points.
1492 If you don't need it: say N
1493 Choose M here to compile this code as a module. The module will be
1494 called lkdtm.
1496 Documentation on how to use the module can be found in
1497 Documentation/fault-injection/provoke-crashes.txt
1499 config TEST_LIST_SORT
1500 bool "Linked list sorting test"
1501 depends on DEBUG_KERNEL
1502 help
1503 Enable this to turn on 'list_sort()' function test. This test is
1504 executed only once during system boot, so affects only boot time.
1506 If unsure, say N.
1508 config KPROBES_SANITY_TEST
1509 bool "Kprobes sanity tests"
1510 depends on DEBUG_KERNEL
1511 depends on KPROBES
1512 default n
1513 help
1514 This option provides for testing basic kprobes functionality on
1515 boot. A sample kprobe, jprobe and kretprobe are inserted and
1516 verified for functionality.
1518 Say N if you are unsure.
1520 config BACKTRACE_SELF_TEST
1521 tristate "Self test for the backtrace code"
1522 depends on DEBUG_KERNEL
1523 default n
1524 help
1525 This option provides a kernel module that can be used to test
1526 the kernel stack backtrace code. This option is not useful
1527 for distributions or general kernels, but only for kernel
1528 developers working on architecture code.
1530 Note that if you want to also test saved backtraces, you will
1531 have to enable STACKTRACE as well.
1533 Say N if you are unsure.
1535 config RBTREE_TEST
1536 tristate "Red-Black tree test"
1537 depends on DEBUG_KERNEL
1538 help
1539 A benchmark measuring the performance of the rbtree library.
1540 Also includes rbtree invariant checks.
1542 config INTERVAL_TREE_TEST
1543 tristate "Interval tree test"
1544 depends on m && DEBUG_KERNEL
1545 select INTERVAL_TREE
1546 help
1547 A benchmark measuring the performance of the interval tree library
1549 config PERCPU_TEST
1550 tristate "Per cpu operations test"
1551 depends on m && DEBUG_KERNEL
1552 help
1553 Enable this option to build test module which validates per-cpu
1554 operations.
1556 If unsure, say N.
1558 config ATOMIC64_SELFTEST
1559 bool "Perform an atomic64_t self-test at boot"
1560 help
1561 Enable this option to test the atomic64_t functions at boot.
1563 If unsure, say N.
1565 config ASYNC_RAID6_TEST
1566 tristate "Self test for hardware accelerated raid6 recovery"
1567 depends on ASYNC_RAID6_RECOV
1568 select ASYNC_MEMCPY
1569 ---help---
1570 This is a one-shot self test that permutes through the
1571 recovery of all the possible two disk failure scenarios for a
1572 N-disk array. Recovery is performed with the asynchronous
1573 raid6 recovery routines, and will optionally use an offload
1574 engine if one is available.
1576 If unsure, say N.
1578 config TEST_STRING_HELPERS
1579 tristate "Test functions located in the string_helpers module at runtime"
1581 config TEST_KSTRTOX
1582 tristate "Test kstrto*() family of functions at runtime"
1584 config TEST_RHASHTABLE
1585 bool "Perform selftest on resizable hash table"
1586 default n
1587 help
1588 Enable this option to test the rhashtable functions at boot.
1590 If unsure, say N.
1592 endmenu # runtime tests
1594 config PROVIDE_OHCI1394_DMA_INIT
1595 bool "Remote debugging over FireWire early on boot"
1596 depends on PCI && X86
1597 help
1598 If you want to debug problems which hang or crash the kernel early
1599 on boot and the crashing machine has a FireWire port, you can use
1600 this feature to remotely access the memory of the crashed machine
1601 over FireWire. This employs remote DMA as part of the OHCI1394
1602 specification which is now the standard for FireWire controllers.
1604 With remote DMA, you can monitor the printk buffer remotely using
1605 firescope and access all memory below 4GB using fireproxy from gdb.
1606 Even controlling a kernel debugger is possible using remote DMA.
1608 Usage:
1610 If ohci1394_dma=early is used as boot parameter, it will initialize
1611 all OHCI1394 controllers which are found in the PCI config space.
1613 As all changes to the FireWire bus such as enabling and disabling
1614 devices cause a bus reset and thereby disable remote DMA for all
1615 devices, be sure to have the cable plugged and FireWire enabled on
1616 the debugging host before booting the debug target for debugging.
1618 This code (~1k) is freed after boot. By then, the firewire stack
1619 in charge of the OHCI-1394 controllers should be used instead.
1621 See Documentation/debugging-via-ohci1394.txt for more information.
1623 config BUILD_DOCSRC
1624 bool "Build targets in Documentation/ tree"
1625 depends on HEADERS_CHECK
1626 help
1627 This option attempts to build objects from the source files in the
1628 kernel Documentation/ tree.
1630 Say N if you are unsure.
1632 config DMA_API_DEBUG
1633 bool "Enable debugging of DMA-API usage"
1634 depends on HAVE_DMA_API_DEBUG
1635 help
1636 Enable this option to debug the use of the DMA API by device drivers.
1637 With this option you will be able to detect common bugs in device
1638 drivers like double-freeing of DMA mappings or freeing mappings that
1639 were never allocated.
1641 This also attempts to catch cases where a page owned by DMA is
1642 accessed by the cpu in a way that could cause data corruption. For
1643 example, this enables cow_user_page() to check that the source page is
1644 not undergoing DMA.
1646 This option causes a performance degradation. Use only if you want to
1647 debug device drivers and dma interactions.
1649 If unsure, say N.
1651 config TEST_LKM
1652 tristate "Test module loading with 'hello world' module"
1653 default n
1654 depends on m
1655 help
1656 This builds the "test_module" module that emits "Hello, world"
1657 on printk when loaded. It is designed to be used for basic
1658 evaluation of the module loading subsystem (for example when
1659 validating module verification). It lacks any extra dependencies,
1660 and will not normally be loaded by the system unless explicitly
1661 requested by name.
1663 If unsure, say N.
1665 config TEST_USER_COPY
1666 tristate "Test user/kernel boundary protections"
1667 default n
1668 depends on m
1669 help
1670 This builds the "test_user_copy" module that runs sanity checks
1671 on the copy_to/from_user infrastructure, making sure basic
1672 user/kernel boundary testing is working. If it fails to load,
1673 a regression has been detected in the user/kernel memory boundary
1674 protections.
1676 If unsure, say N.
1678 config TEST_BPF
1679 tristate "Test BPF filter functionality"
1680 default n
1681 depends on m && NET
1682 help
1683 This builds the "test_bpf" module that runs various test vectors
1684 against the BPF interpreter or BPF JIT compiler depending on the
1685 current setting. This is in particular useful for BPF JIT compiler
1686 development, but also to run regression tests against changes in
1687 the interpreter code. It also enables test stubs for eBPF maps and
1688 verifier used by user space verifier testsuite.
1690 If unsure, say N.
1692 config TEST_FIRMWARE
1693 tristate "Test firmware loading via userspace interface"
1694 default n
1695 depends on FW_LOADER
1696 help
1697 This builds the "test_firmware" module that creates a userspace
1698 interface for testing firmware loading. This can be used to
1699 control the triggering of firmware loading without needing an
1700 actual firmware-using device. The contents can be rechecked by
1701 userspace.
1703 If unsure, say N.
1705 config TEST_UDELAY
1706 tristate "udelay test driver"
1707 default n
1708 help
1709 This builds the "udelay_test" module that helps to make sure
1710 that udelay() is working properly.
1712 If unsure, say N.
1714 source "samples/Kconfig"
1716 source "lib/Kconfig.kgdb"