| blob | 5f2ce616c0462db9b9055528110268385b2b653e |
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 PAGE_OWNER
231 bool "Track page owner"
232 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
233 select DEBUG_FS
234 select STACKTRACE
235 select PAGE_EXTENSION
236 help
237 This keeps track of what call chain is the owner of a page, may
238 help to find bare alloc_page(s) leaks. Even if you include this
239 feature on your build, it is disabled in default. You should pass
240 "page_owner=on" to boot parameter in order to enable it. Eats
241 a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
242 for user-space helper.
244 If unsure, say N.
246 config DEBUG_FS
247 bool "Debug Filesystem"
248 help
249 debugfs is a virtual file system that kernel developers use to put
250 debugging files into. Enable this option to be able to read and
251 write to these files.
253 For detailed documentation on the debugfs API, see
254 Documentation/DocBook/filesystems.
256 If unsure, say N.
258 config HEADERS_CHECK
259 bool "Run 'make headers_check' when building vmlinux"
260 depends on !UML
261 help
262 This option will extract the user-visible kernel headers whenever
263 building the kernel, and will run basic sanity checks on them to
264 ensure that exported files do not attempt to include files which
265 were not exported, etc.
267 If you're making modifications to header files which are
268 relevant for userspace, say 'Y', and check the headers
269 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
270 your build tree), to make sure they're suitable.
272 config DEBUG_SECTION_MISMATCH
273 bool "Enable full Section mismatch analysis"
274 help
275 The section mismatch analysis checks if there are illegal
276 references from one section to another section.
277 During linktime or runtime, some sections are dropped;
278 any use of code/data previously in these sections would
279 most likely result in an oops.
280 In the code, functions and variables are annotated with
281 __init,, etc. (see the full list in include/linux/init.h),
282 which results in the code/data being placed in specific sections.
283 The section mismatch analysis is always performed after a full
284 kernel build, and enabling this option causes the following
285 additional steps to occur:
286 - Add the option -fno-inline-functions-called-once to gcc commands.
287 When inlining a function annotated with __init in a non-init
288 function, we would lose the section information and thus
289 the analysis would not catch the illegal reference.
290 This option tells gcc to inline less (but it does result in
291 a larger kernel).
292 - Run the section mismatch analysis for each module/built-in.o file.
293 When we run the section mismatch analysis on vmlinux.o, we
294 lose valueble information about where the mismatch was
295 introduced.
296 Running the analysis for each module/built-in.o file
297 tells where the mismatch happens much closer to the
298 source. The drawback is that the same mismatch is
299 reported at least twice.
300 - Enable verbose reporting from modpost in order to help resolve
301 the section mismatches that are reported.
303 #
304 # Select this config option from the architecture Kconfig, if it
305 # is preferred to always offer frame pointers as a config
306 # option on the architecture (regardless of KERNEL_DEBUG):
307 #
308 config ARCH_WANT_FRAME_POINTERS
309 bool
310 help
312 config FRAME_POINTER
313 bool "Compile the kernel with frame pointers"
314 depends on DEBUG_KERNEL && \
315 (CRIS || M68K || FRV || UML || \
316 AVR32 || SUPERH || BLACKFIN || MN10300 || METAG) || \
317 ARCH_WANT_FRAME_POINTERS
318 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
319 help
320 If you say Y here the resulting kernel image will be slightly
321 larger and slower, but it gives very useful debugging information
322 in case of kernel bugs. (precise oopses/stacktraces/warnings)
324 config DEBUG_FORCE_WEAK_PER_CPU
325 bool "Force weak per-cpu definitions"
326 depends on DEBUG_KERNEL
327 help
328 s390 and alpha require percpu variables in modules to be
329 defined weak to work around addressing range issue which
330 puts the following two restrictions on percpu variable
331 definitions.
333 1. percpu symbols must be unique whether static or not
334 2. percpu variables can't be defined inside a function
336 To ensure that generic code follows the above rules, this
337 option forces all percpu variables to be defined as weak.
339 endmenu # "Compiler options"
341 config MAGIC_SYSRQ
342 bool "Magic SysRq key"
343 depends on !UML
344 help
345 If you say Y here, you will have some control over the system even
346 if the system crashes for example during kernel debugging (e.g., you
347 will be able to flush the buffer cache to disk, reboot the system
348 immediately or dump some status information). This is accomplished
349 by pressing various keys while holding SysRq (Alt+PrintScreen). It
350 also works on a serial console (on PC hardware at least), if you
351 send a BREAK and then within 5 seconds a command keypress. The
352 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
353 unless you really know what this hack does.
355 config MAGIC_SYSRQ_DEFAULT_ENABLE
356 hex "Enable magic SysRq key functions by default"
357 depends on MAGIC_SYSRQ
358 default 0x1
359 help
360 Specifies which SysRq key functions are enabled by default.
361 This may be set to 1 or 0 to enable or disable them all, or
362 to a bitmask as described in Documentation/sysrq.txt.
364 config DEBUG_KERNEL
365 bool "Kernel debugging"
366 help
367 Say Y here if you are developing drivers or trying to debug and
368 identify kernel problems.
370 menu "Memory Debugging"
372 source mm/Kconfig.debug
374 config DEBUG_OBJECTS
375 bool "Debug object operations"
376 depends on DEBUG_KERNEL
377 help
378 If you say Y here, additional code will be inserted into the
379 kernel to track the life time of various objects and validate
380 the operations on those objects.
382 config DEBUG_OBJECTS_SELFTEST
383 bool "Debug objects selftest"
384 depends on DEBUG_OBJECTS
385 help
386 This enables the selftest of the object debug code.
388 config DEBUG_OBJECTS_FREE
389 bool "Debug objects in freed memory"
390 depends on DEBUG_OBJECTS
391 help
392 This enables checks whether a k/v free operation frees an area
393 which contains an object which has not been deactivated
394 properly. This can make kmalloc/kfree-intensive workloads
395 much slower.
397 config DEBUG_OBJECTS_TIMERS
398 bool "Debug timer objects"
399 depends on DEBUG_OBJECTS
400 help
401 If you say Y here, additional code will be inserted into the
402 timer routines to track the life time of timer objects and
403 validate the timer operations.
405 config DEBUG_OBJECTS_WORK
406 bool "Debug work objects"
407 depends on DEBUG_OBJECTS
408 help
409 If you say Y here, additional code will be inserted into the
410 work queue routines to track the life time of work objects and
411 validate the work operations.
413 config DEBUG_OBJECTS_RCU_HEAD
414 bool "Debug RCU callbacks objects"
415 depends on DEBUG_OBJECTS
416 help
417 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
419 config DEBUG_OBJECTS_PERCPU_COUNTER
420 bool "Debug percpu counter objects"
421 depends on DEBUG_OBJECTS
422 help
423 If you say Y here, additional code will be inserted into the
424 percpu counter routines to track the life time of percpu counter
425 objects and validate the percpu counter operations.
427 config DEBUG_OBJECTS_ENABLE_DEFAULT
428 int "debug_objects bootup default value (0-1)"
429 range 0 1
430 default "1"
431 depends on DEBUG_OBJECTS
432 help
433 Debug objects boot parameter default value
435 config DEBUG_SLAB
436 bool "Debug slab memory allocations"
437 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
438 help
439 Say Y here to have the kernel do limited verification on memory
440 allocation as well as poisoning memory on free to catch use of freed
441 memory. This can make kmalloc/kfree-intensive workloads much slower.
443 config DEBUG_SLAB_LEAK
444 bool "Memory leak debugging"
445 depends on DEBUG_SLAB
447 config SLUB_DEBUG_ON
448 bool "SLUB debugging on by default"
449 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
450 default n
451 help
452 Boot with debugging on by default. SLUB boots by default with
453 the runtime debug capabilities switched off. Enabling this is
454 equivalent to specifying the "slub_debug" parameter on boot.
455 There is no support for more fine grained debug control like
456 possible with slub_debug=xxx. SLUB debugging may be switched
457 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
458 "slub_debug=-".
460 config SLUB_STATS
461 default n
462 bool "Enable SLUB performance statistics"
463 depends on SLUB && SYSFS
464 help
465 SLUB statistics are useful to debug SLUBs allocation behavior in
466 order find ways to optimize the allocator. This should never be
467 enabled for production use since keeping statistics slows down
468 the allocator by a few percentage points. The slabinfo command
469 supports the determination of the most active slabs to figure
470 out which slabs are relevant to a particular load.
471 Try running: slabinfo -DA
473 config HAVE_DEBUG_KMEMLEAK
474 bool
476 config DEBUG_KMEMLEAK
477 bool "Kernel memory leak detector"
478 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
479 select DEBUG_FS
480 select STACKTRACE if STACKTRACE_SUPPORT
481 select KALLSYMS
482 select CRC32
483 help
484 Say Y here if you want to enable the memory leak
485 detector. The memory allocation/freeing is traced in a way
486 similar to the Boehm's conservative garbage collector, the
487 difference being that the orphan objects are not freed but
488 only shown in /sys/kernel/debug/kmemleak. Enabling this
489 feature will introduce an overhead to memory
490 allocations. See Documentation/kmemleak.txt for more
491 details.
493 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
494 of finding leaks due to the slab objects poisoning.
496 In order to access the kmemleak file, debugfs needs to be
497 mounted (usually at /sys/kernel/debug).
499 config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
500 int "Maximum kmemleak early log entries"
501 depends on DEBUG_KMEMLEAK
502 range 200 40000
503 default 400
504 help
505 Kmemleak must track all the memory allocations to avoid
506 reporting false positives. Since memory may be allocated or
507 freed before kmemleak is initialised, an early log buffer is
508 used to store these actions. If kmemleak reports "early log
509 buffer exceeded", please increase this value.
511 config DEBUG_KMEMLEAK_TEST
512 tristate "Simple test for the kernel memory leak detector"
513 depends on DEBUG_KMEMLEAK && m
514 help
515 This option enables a module that explicitly leaks memory.
517 If unsure, say N.
519 config DEBUG_KMEMLEAK_DEFAULT_OFF
520 bool "Default kmemleak to off"
521 depends on DEBUG_KMEMLEAK
522 help
523 Say Y here to disable kmemleak by default. It can then be enabled
524 on the command line via kmemleak=on.
526 config DEBUG_STACK_USAGE
527 bool "Stack utilization instrumentation"
528 depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
529 help
530 Enables the display of the minimum amount of free stack which each
531 task has ever had available in the sysrq-T and sysrq-P debug output.
533 This option will slow down process creation somewhat.
535 config DEBUG_VM
536 bool "Debug VM"
537 depends on DEBUG_KERNEL
538 help
539 Enable this to turn on extended checks in the virtual-memory system
540 that may impact performance.
542 If unsure, say N.
544 config DEBUG_VM_VMACACHE
545 bool "Debug VMA caching"
546 depends on DEBUG_VM
547 help
548 Enable this to turn on VMA caching debug information. Doing so
549 can cause significant overhead, so only enable it in non-production
550 environments.
552 If unsure, say N.
554 config DEBUG_VM_RB
555 bool "Debug VM red-black trees"
556 depends on DEBUG_VM
557 help
558 Enable VM red-black tree debugging information and extra validations.
560 If unsure, say N.
562 config DEBUG_VIRTUAL
563 bool "Debug VM translations"
564 depends on DEBUG_KERNEL && X86
565 help
566 Enable some costly sanity checks in virtual to page code. This can
567 catch mistakes with virt_to_page() and friends.
569 If unsure, say N.
571 config DEBUG_NOMMU_REGIONS
572 bool "Debug the global anon/private NOMMU mapping region tree"
573 depends on DEBUG_KERNEL && !MMU
574 help
575 This option causes the global tree of anonymous and private mapping
576 regions to be regularly checked for invalid topology.
578 config DEBUG_MEMORY_INIT
579 bool "Debug memory initialisation" if EXPERT
580 default !EXPERT
581 help
582 Enable this for additional checks during memory initialisation.
583 The sanity checks verify aspects of the VM such as the memory model
584 and other information provided by the architecture. Verbose
585 information will be printed at KERN_DEBUG loglevel depending
586 on the mminit_loglevel= command-line option.
588 If unsure, say Y
590 config MEMORY_NOTIFIER_ERROR_INJECT
591 tristate "Memory hotplug notifier error injection module"
592 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
593 help
594 This option provides the ability to inject artificial errors to
595 memory hotplug notifier chain callbacks. It is controlled through
596 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
598 If the notifier call chain should be failed with some events
599 notified, write the error code to "actions/<notifier event>/error".
601 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
603 # cd /sys/kernel/debug/notifier-error-inject/memory
604 # echo -12 > actions/MEM_GOING_OFFLINE/error
605 # echo offline > /sys/devices/system/memory/memoryXXX/state
606 bash: echo: write error: Cannot allocate memory
608 To compile this code as a module, choose M here: the module will
609 be called memory-notifier-error-inject.
611 If unsure, say N.
613 config DEBUG_PER_CPU_MAPS
614 bool "Debug access to per_cpu maps"
615 depends on DEBUG_KERNEL
616 depends on SMP
617 help
618 Say Y to verify that the per_cpu map being accessed has
619 been set up. This adds a fair amount of code to kernel memory
620 and decreases performance.
622 Say N if unsure.
624 config DEBUG_HIGHMEM
625 bool "Highmem debugging"
626 depends on DEBUG_KERNEL && HIGHMEM
627 help
628 This option enables additional error checking for high memory
629 systems. Disable for production systems.
631 config HAVE_DEBUG_STACKOVERFLOW
632 bool
634 config DEBUG_STACKOVERFLOW
635 bool "Check for stack overflows"
636 depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
637 ---help---
638 Say Y here if you want to check for overflows of kernel, IRQ
639 and exception stacks (if your archicture uses them). This
640 option will show detailed messages if free stack space drops
641 below a certain limit.
643 These kinds of bugs usually occur when call-chains in the
644 kernel get too deep, especially when interrupts are
645 involved.
647 Use this in cases where you see apparently random memory
648 corruption, especially if it appears in 'struct thread_info'
650 If in doubt, say "N".
652 source "lib/Kconfig.kmemcheck"
654 endmenu # "Memory Debugging"
656 config DEBUG_SHIRQ
657 bool "Debug shared IRQ handlers"
658 depends on DEBUG_KERNEL
659 help
660 Enable this to generate a spurious interrupt as soon as a shared
661 interrupt handler is registered, and just before one is deregistered.
662 Drivers ought to be able to handle interrupts coming in at those
663 points; some don't and need to be caught.
665 menu "Debug Lockups and Hangs"
667 config LOCKUP_DETECTOR
668 bool "Detect Hard and Soft Lockups"
669 depends on DEBUG_KERNEL && !S390
670 help
671 Say Y here to enable the kernel to act as a watchdog to detect
672 hard and soft lockups.
674 Softlockups are bugs that cause the kernel to loop in kernel
675 mode for more than 20 seconds, without giving other tasks a
676 chance to run. The current stack trace is displayed upon
677 detection and the system will stay locked up.
679 Hardlockups are bugs that cause the CPU to loop in kernel mode
680 for more than 10 seconds, without letting other interrupts have a
681 chance to run. The current stack trace is displayed upon detection
682 and the system will stay locked up.
684 The overhead should be minimal. A periodic hrtimer runs to
685 generate interrupts and kick the watchdog task every 4 seconds.
686 An NMI is generated every 10 seconds or so to check for hardlockups.
688 The frequency of hrtimer and NMI events and the soft and hard lockup
689 thresholds can be controlled through the sysctl watchdog_thresh.
691 config HARDLOCKUP_DETECTOR
692 def_bool y
693 depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
694 depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
696 config BOOTPARAM_HARDLOCKUP_PANIC
697 bool "Panic (Reboot) On Hard Lockups"
698 depends on HARDLOCKUP_DETECTOR
699 help
700 Say Y here to enable the kernel to panic on "hard lockups",
701 which are bugs that cause the kernel to loop in kernel
702 mode with interrupts disabled for more than 10 seconds (configurable
703 using the watchdog_thresh sysctl).
705 Say N if unsure.
707 config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
708 int
709 depends on HARDLOCKUP_DETECTOR
710 range 0 1
711 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
712 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
714 config BOOTPARAM_SOFTLOCKUP_PANIC
715 bool "Panic (Reboot) On Soft Lockups"
716 depends on LOCKUP_DETECTOR
717 help
718 Say Y here to enable the kernel to panic on "soft lockups",
719 which are bugs that cause the kernel to loop in kernel
720 mode for more than 20 seconds (configurable using the watchdog_thresh
721 sysctl), without giving other tasks a chance to run.
723 The panic can be used in combination with panic_timeout,
724 to cause the system to reboot automatically after a
725 lockup has been detected. This feature is useful for
726 high-availability systems that have uptime guarantees and
727 where a lockup must be resolved ASAP.
729 Say N if unsure.
731 config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
732 int
733 depends on LOCKUP_DETECTOR
734 range 0 1
735 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
736 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
738 config DETECT_HUNG_TASK
739 bool "Detect Hung Tasks"
740 depends on DEBUG_KERNEL
741 default LOCKUP_DETECTOR
742 help
743 Say Y here to enable the kernel to detect "hung tasks",
744 which are bugs that cause the task to be stuck in
745 uninterruptible "D" state indefinitiley.
747 When a hung task is detected, the kernel will print the
748 current stack trace (which you should report), but the
749 task will stay in uninterruptible state. If lockdep is
750 enabled then all held locks will also be reported. This
751 feature has negligible overhead.
753 config DEFAULT_HUNG_TASK_TIMEOUT
754 int "Default timeout for hung task detection (in seconds)"
755 depends on DETECT_HUNG_TASK
756 default 120
757 help
758 This option controls the default timeout (in seconds) used
759 to determine when a task has become non-responsive and should
760 be considered hung.
762 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
763 sysctl or by writing a value to
764 /proc/sys/kernel/hung_task_timeout_secs.
766 A timeout of 0 disables the check. The default is two minutes.
767 Keeping the default should be fine in most cases.
769 config BOOTPARAM_HUNG_TASK_PANIC
770 bool "Panic (Reboot) On Hung Tasks"
771 depends on DETECT_HUNG_TASK
772 help
773 Say Y here to enable the kernel to panic on "hung tasks",
774 which are bugs that cause the kernel to leave a task stuck
775 in uninterruptible "D" state.
777 The panic can be used in combination with panic_timeout,
778 to cause the system to reboot automatically after a
779 hung task has been detected. This feature is useful for
780 high-availability systems that have uptime guarantees and
781 where a hung tasks must be resolved ASAP.
783 Say N if unsure.
785 config BOOTPARAM_HUNG_TASK_PANIC_VALUE
786 int
787 depends on DETECT_HUNG_TASK
788 range 0 1
789 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
790 default 1 if BOOTPARAM_HUNG_TASK_PANIC
792 endmenu # "Debug lockups and hangs"
794 config PANIC_ON_OOPS
795 bool "Panic on Oops"
796 help
797 Say Y here to enable the kernel to panic when it oopses. This
798 has the same effect as setting oops=panic on the kernel command
799 line.
801 This feature is useful to ensure that the kernel does not do
802 anything erroneous after an oops which could result in data
803 corruption or other issues.
805 Say N if unsure.
807 config PANIC_ON_OOPS_VALUE
808 int
809 range 0 1
810 default 0 if !PANIC_ON_OOPS
811 default 1 if PANIC_ON_OOPS
813 config PANIC_TIMEOUT
814 int "panic timeout"
815 default 0
816 help
817 Set the timeout value (in seconds) until a reboot occurs when the
818 the kernel panics. If n = 0, then we wait forever. A timeout
819 value n > 0 will wait n seconds before rebooting, while a timeout
820 value n < 0 will reboot immediately.
822 config SCHED_DEBUG
823 bool "Collect scheduler debugging info"
824 depends on DEBUG_KERNEL && PROC_FS
825 default y
826 help
827 If you say Y here, the /proc/sched_debug file will be provided
828 that can help debug the scheduler. The runtime overhead of this
829 option is minimal.
831 config SCHEDSTATS
832 bool "Collect scheduler statistics"
833 depends on DEBUG_KERNEL && PROC_FS
834 help
835 If you say Y here, additional code will be inserted into the
836 scheduler and related routines to collect statistics about
837 scheduler behavior and provide them in /proc/schedstat. These
838 stats may be useful for both tuning and debugging the scheduler
839 If you aren't debugging the scheduler or trying to tune a specific
840 application, you can say N to avoid the very slight overhead
841 this adds.
843 config SCHED_STACK_END_CHECK
844 bool "Detect stack corruption on calls to schedule()"
845 depends on DEBUG_KERNEL
846 default n
847 help
848 This option checks for a stack overrun on calls to schedule().
849 If the stack end location is found to be over written always panic as
850 the content of the corrupted region can no longer be trusted.
851 This is to ensure no erroneous behaviour occurs which could result in
852 data corruption or a sporadic crash at a later stage once the region
853 is examined. The runtime overhead introduced is minimal.
855 config TIMER_STATS
856 bool "Collect kernel timers statistics"
857 depends on DEBUG_KERNEL && PROC_FS
858 help
859 If you say Y here, additional code will be inserted into the
860 timer routines to collect statistics about kernel timers being
861 reprogrammed. The statistics can be read from /proc/timer_stats.
862 The statistics collection is started by writing 1 to /proc/timer_stats,
863 writing 0 stops it. This feature is useful to collect information
864 about timer usage patterns in kernel and userspace. This feature
865 is lightweight if enabled in the kernel config but not activated
866 (it defaults to deactivated on bootup and will only be activated
867 if some application like powertop activates it explicitly).
869 config DEBUG_PREEMPT
870 bool "Debug preemptible kernel"
871 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
872 default y
873 help
874 If you say Y here then the kernel will use a debug variant of the
875 commonly used smp_processor_id() function and will print warnings
876 if kernel code uses it in a preemption-unsafe way. Also, the kernel
877 will detect preemption count underflows.
879 menu "Lock Debugging (spinlocks, mutexes, etc...)"
881 config DEBUG_RT_MUTEXES
882 bool "RT Mutex debugging, deadlock detection"
883 depends on DEBUG_KERNEL && RT_MUTEXES
884 help
885 This allows rt mutex semantics violations and rt mutex related
886 deadlocks (lockups) to be detected and reported automatically.
888 config RT_MUTEX_TESTER
889 bool "Built-in scriptable tester for rt-mutexes"
890 depends on DEBUG_KERNEL && RT_MUTEXES && BROKEN
891 help
892 This option enables a rt-mutex tester.
894 config DEBUG_SPINLOCK
895 bool "Spinlock and rw-lock debugging: basic checks"
896 depends on DEBUG_KERNEL
897 select UNINLINE_SPIN_UNLOCK
898 help
899 Say Y here and build SMP to catch missing spinlock initialization
900 and certain other kinds of spinlock errors commonly made. This is
901 best used in conjunction with the NMI watchdog so that spinlock
902 deadlocks are also debuggable.
904 config DEBUG_MUTEXES
905 bool "Mutex debugging: basic checks"
906 depends on DEBUG_KERNEL
907 help
908 This feature allows mutex semantics violations to be detected and
909 reported.
911 config DEBUG_WW_MUTEX_SLOWPATH
912 bool "Wait/wound mutex debugging: Slowpath testing"
913 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
914 select DEBUG_LOCK_ALLOC
915 select DEBUG_SPINLOCK
916 select DEBUG_MUTEXES
917 help
918 This feature enables slowpath testing for w/w mutex users by
919 injecting additional -EDEADLK wound/backoff cases. Together with
920 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
921 will test all possible w/w mutex interface abuse with the
922 exception of simply not acquiring all the required locks.
923 Note that this feature can introduce significant overhead, so
924 it really should not be enabled in a production or distro kernel,
925 even a debug kernel. If you are a driver writer, enable it. If
926 you are a distro, do not.
928 config DEBUG_LOCK_ALLOC
929 bool "Lock debugging: detect incorrect freeing of live locks"
930 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
931 select DEBUG_SPINLOCK
932 select DEBUG_MUTEXES
933 select LOCKDEP
934 help
935 This feature will check whether any held lock (spinlock, rwlock,
936 mutex or rwsem) is incorrectly freed by the kernel, via any of the
937 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
938 vfree(), etc.), whether a live lock is incorrectly reinitialized via
939 spin_lock_init()/mutex_init()/etc., or whether there is any lock
940 held during task exit.
942 config PROVE_LOCKING
943 bool "Lock debugging: prove locking correctness"
944 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
945 select LOCKDEP
946 select DEBUG_SPINLOCK
947 select DEBUG_MUTEXES
948 select DEBUG_LOCK_ALLOC
949 select TRACE_IRQFLAGS
950 default n
951 help
952 This feature enables the kernel to prove that all locking
953 that occurs in the kernel runtime is mathematically
954 correct: that under no circumstance could an arbitrary (and
955 not yet triggered) combination of observed locking
956 sequences (on an arbitrary number of CPUs, running an
957 arbitrary number of tasks and interrupt contexts) cause a
958 deadlock.
960 In short, this feature enables the kernel to report locking
961 related deadlocks before they actually occur.
963 The proof does not depend on how hard and complex a
964 deadlock scenario would be to trigger: how many
965 participant CPUs, tasks and irq-contexts would be needed
966 for it to trigger. The proof also does not depend on
967 timing: if a race and a resulting deadlock is possible
968 theoretically (no matter how unlikely the race scenario
969 is), it will be proven so and will immediately be
970 reported by the kernel (once the event is observed that
971 makes the deadlock theoretically possible).
973 If a deadlock is impossible (i.e. the locking rules, as
974 observed by the kernel, are mathematically correct), the
975 kernel reports nothing.
977 NOTE: this feature can also be enabled for rwlocks, mutexes
978 and rwsems - in which case all dependencies between these
979 different locking variants are observed and mapped too, and
980 the proof of observed correctness is also maintained for an
981 arbitrary combination of these separate locking variants.
983 For more details, see Documentation/locking/lockdep-design.txt.
985 config LOCKDEP
986 bool
987 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
988 select STACKTRACE
989 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE
990 select KALLSYMS
991 select KALLSYMS_ALL
993 config LOCK_STAT
994 bool "Lock usage statistics"
995 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
996 select LOCKDEP
997 select DEBUG_SPINLOCK
998 select DEBUG_MUTEXES
999 select DEBUG_LOCK_ALLOC
1000 default n
1001 help
1002 This feature enables tracking lock contention points
1004 For more details, see Documentation/locking/lockstat.txt
1006 This also enables lock events required by "perf lock",
1007 subcommand of perf.
1008 If you want to use "perf lock", you also need to turn on
1009 CONFIG_EVENT_TRACING.
1011 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1012 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1014 config DEBUG_LOCKDEP
1015 bool "Lock dependency engine debugging"
1016 depends on DEBUG_KERNEL && LOCKDEP
1017 help
1018 If you say Y here, the lock dependency engine will do
1019 additional runtime checks to debug itself, at the price
1020 of more runtime overhead.
1022 config DEBUG_ATOMIC_SLEEP
1023 bool "Sleep inside atomic section checking"
1024 select PREEMPT_COUNT
1025 depends on DEBUG_KERNEL
1026 help
1027 If you say Y here, various routines which may sleep will become very
1028 noisy if they are called inside atomic sections: when a spinlock is
1029 held, inside an rcu read side critical section, inside preempt disabled
1030 sections, inside an interrupt, etc...
1032 config DEBUG_LOCKING_API_SELFTESTS
1033 bool "Locking API boot-time self-tests"
1034 depends on DEBUG_KERNEL
1035 help
1036 Say Y here if you want the kernel to run a short self-test during
1037 bootup. The self-test checks whether common types of locking bugs
1038 are detected by debugging mechanisms or not. (if you disable
1039 lock debugging then those bugs wont be detected of course.)
1040 The following locking APIs are covered: spinlocks, rwlocks,
1041 mutexes and rwsems.
1043 config LOCK_TORTURE_TEST
1044 tristate "torture tests for locking"
1045 depends on DEBUG_KERNEL
1046 select TORTURE_TEST
1047 default n
1048 help
1049 This option provides a kernel module that runs torture tests
1050 on kernel locking primitives. The kernel module may be built
1051 after the fact on the running kernel to be tested, if desired.
1053 Say Y here if you want kernel locking-primitive torture tests
1054 to be built into the kernel.
1055 Say M if you want these torture tests to build as a module.
1056 Say N if you are unsure.
1058 endmenu # lock debugging
1060 config TRACE_IRQFLAGS
1061 bool
1062 help
1063 Enables hooks to interrupt enabling and disabling for
1064 either tracing or lock debugging.
1066 config STACKTRACE
1067 bool "Stack backtrace support"
1068 depends on STACKTRACE_SUPPORT
1069 help
1070 This option causes the kernel to create a /proc/pid/stack for
1071 every process, showing its current stack trace.
1072 It is also used by various kernel debugging features that require
1073 stack trace generation.
1075 config DEBUG_KOBJECT
1076 bool "kobject debugging"
1077 depends on DEBUG_KERNEL
1078 help
1079 If you say Y here, some extra kobject debugging messages will be sent
1080 to the syslog.
1082 config DEBUG_KOBJECT_RELEASE
1083 bool "kobject release debugging"
1084 depends on DEBUG_OBJECTS_TIMERS
1085 help
1086 kobjects are reference counted objects. This means that their
1087 last reference count put is not predictable, and the kobject can
1088 live on past the point at which a driver decides to drop it's
1089 initial reference to the kobject gained on allocation. An
1090 example of this would be a struct device which has just been
1091 unregistered.
1093 However, some buggy drivers assume that after such an operation,
1094 the memory backing the kobject can be immediately freed. This
1095 goes completely against the principles of a refcounted object.
1097 If you say Y here, the kernel will delay the release of kobjects
1098 on the last reference count to improve the visibility of this
1099 kind of kobject release bug.
1101 config HAVE_DEBUG_BUGVERBOSE
1102 bool
1104 config DEBUG_BUGVERBOSE
1105 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1106 depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1107 default y
1108 help
1109 Say Y here to make BUG() panics output the file name and line number
1110 of the BUG call as well as the EIP and oops trace. This aids
1111 debugging but costs about 70-100K of memory.
1113 config DEBUG_LIST
1114 bool "Debug linked list manipulation"
1115 depends on DEBUG_KERNEL
1116 help
1117 Enable this to turn on extended checks in the linked-list
1118 walking routines.
1120 If unsure, say N.
1122 config DEBUG_PI_LIST
1123 bool "Debug priority linked list manipulation"
1124 depends on DEBUG_KERNEL
1125 help
1126 Enable this to turn on extended checks in the priority-ordered
1127 linked-list (plist) walking routines. This checks the entire
1128 list multiple times during each manipulation.
1130 If unsure, say N.
1132 config DEBUG_SG
1133 bool "Debug SG table operations"
1134 depends on DEBUG_KERNEL
1135 help
1136 Enable this to turn on checks on scatter-gather tables. This can
1137 help find problems with drivers that do not properly initialize
1138 their sg tables.
1140 If unsure, say N.
1142 config DEBUG_NOTIFIERS
1143 bool "Debug notifier call chains"
1144 depends on DEBUG_KERNEL
1145 help
1146 Enable this to turn on sanity checking for notifier call chains.
1147 This is most useful for kernel developers to make sure that
1148 modules properly unregister themselves from notifier chains.
1149 This is a relatively cheap check but if you care about maximum
1150 performance, say N.
1152 config DEBUG_CREDENTIALS
1153 bool "Debug credential management"
1154 depends on DEBUG_KERNEL
1155 help
1156 Enable this to turn on some debug checking for credential
1157 management. The additional code keeps track of the number of
1158 pointers from task_structs to any given cred struct, and checks to
1159 see that this number never exceeds the usage count of the cred
1160 struct.
1162 Furthermore, if SELinux is enabled, this also checks that the
1163 security pointer in the cred struct is never seen to be invalid.
1165 If unsure, say N.
1167 menu "RCU Debugging"
1169 config PROVE_RCU
1170 bool "RCU debugging: prove RCU correctness"
1171 depends on PROVE_LOCKING
1172 default n
1173 help
1174 This feature enables lockdep extensions that check for correct
1175 use of RCU APIs. This is currently under development. Say Y
1176 if you want to debug RCU usage or help work on the PROVE_RCU
1177 feature.
1179 Say N if you are unsure.
1181 config PROVE_RCU_REPEATEDLY
1182 bool "RCU debugging: don't disable PROVE_RCU on first splat"
1183 depends on PROVE_RCU
1184 default n
1185 help
1186 By itself, PROVE_RCU will disable checking upon issuing the
1187 first warning (or "splat"). This feature prevents such
1188 disabling, allowing multiple RCU-lockdep warnings to be printed
1189 on a single reboot.
1191 Say Y to allow multiple RCU-lockdep warnings per boot.
1193 Say N if you are unsure.
1195 config SPARSE_RCU_POINTER
1196 bool "RCU debugging: sparse-based checks for pointer usage"
1197 default n
1198 help
1199 This feature enables the __rcu sparse annotation for
1200 RCU-protected pointers. This annotation will cause sparse
1201 to flag any non-RCU used of annotated pointers. This can be
1202 helpful when debugging RCU usage. Please note that this feature
1203 is not intended to enforce code cleanliness; it is instead merely
1204 a debugging aid.
1206 Say Y to make sparse flag questionable use of RCU-protected pointers
1208 Say N if you are unsure.
1210 config TORTURE_TEST
1211 tristate
1212 default n
1214 config RCU_TORTURE_TEST
1215 tristate "torture tests for RCU"
1216 depends on DEBUG_KERNEL
1217 select TORTURE_TEST
1218 default n
1219 help
1220 This option provides a kernel module that runs torture tests
1221 on the RCU infrastructure. The kernel module may be built
1222 after the fact on the running kernel to be tested, if desired.
1224 Say Y here if you want RCU torture tests to be built into
1225 the kernel.
1226 Say M if you want the RCU torture tests to build as a module.
1227 Say N if you are unsure.
1229 config RCU_TORTURE_TEST_RUNNABLE
1230 bool "torture tests for RCU runnable by default"
1231 depends on RCU_TORTURE_TEST = y
1232 default n
1233 help
1234 This option provides a way to build the RCU torture tests
1235 directly into the kernel without them starting up at boot
1236 time. You can use /proc/sys/kernel/rcutorture_runnable
1237 to manually override this setting. This /proc file is
1238 available only when the RCU torture tests have been built
1239 into the kernel.
1241 Say Y here if you want the RCU torture tests to start during
1242 boot (you probably don't).
1243 Say N here if you want the RCU torture tests to start only
1244 after being manually enabled via /proc.
1246 config RCU_CPU_STALL_TIMEOUT
1247 int "RCU CPU stall timeout in seconds"
1248 depends on RCU_STALL_COMMON
1249 range 3 300
1250 default 21
1251 help
1252 If a given RCU grace period extends more than the specified
1253 number of seconds, a CPU stall warning is printed. If the
1254 RCU grace period persists, additional CPU stall warnings are
1255 printed at more widely spaced intervals.
1257 config RCU_CPU_STALL_INFO
1258 bool "Print additional diagnostics on RCU CPU stall"
1259 depends on (TREE_RCU || PREEMPT_RCU) && DEBUG_KERNEL
1260 default n
1261 help
1262 For each stalled CPU that is aware of the current RCU grace
1263 period, print out additional per-CPU diagnostic information
1264 regarding scheduling-clock ticks, idle state, and,
1265 for RCU_FAST_NO_HZ kernels, idle-entry state.
1267 Say N if you are unsure.
1269 Say Y if you want to enable such diagnostics.
1271 config RCU_TRACE
1272 bool "Enable tracing for RCU"
1273 depends on DEBUG_KERNEL
1274 select TRACE_CLOCK
1275 help
1276 This option provides tracing in RCU which presents stats
1277 in debugfs for debugging RCU implementation.
1279 Say Y here if you want to enable RCU tracing
1280 Say N if you are unsure.
1282 endmenu # "RCU Debugging"
1284 config DEBUG_BLOCK_EXT_DEVT
1285 bool "Force extended block device numbers and spread them"
1286 depends on DEBUG_KERNEL
1287 depends on BLOCK
1288 default n
1289 help
1290 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1291 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1292 YOU ARE DOING. Distros, please enable this and fix whatever
1293 is broken.
1295 Conventionally, block device numbers are allocated from
1296 predetermined contiguous area. However, extended block area
1297 may introduce non-contiguous block device numbers. This
1298 option forces most block device numbers to be allocated from
1299 the extended space and spreads them to discover kernel or
1300 userland code paths which assume predetermined contiguous
1301 device number allocation.
1303 Note that turning on this debug option shuffles all the
1304 device numbers for all IDE and SCSI devices including libata
1305 ones, so root partition specified using device number
1306 directly (via rdev or root=MAJ:MIN) won't work anymore.
1307 Textual device names (root=/dev/sdXn) will continue to work.
1309 Say N if you are unsure.
1311 config NOTIFIER_ERROR_INJECTION
1312 tristate "Notifier error injection"
1313 depends on DEBUG_KERNEL
1314 select DEBUG_FS
1315 help
1316 This option provides the ability to inject artificial errors to
1317 specified notifier chain callbacks. It is useful to test the error
1318 handling of notifier call chain failures.
1320 Say N if unsure.
1322 config CPU_NOTIFIER_ERROR_INJECT
1323 tristate "CPU notifier error injection module"
1324 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1325 help
1326 This option provides a kernel module that can be used to test
1327 the error handling of the cpu notifiers by injecting artificial
1328 errors to CPU notifier chain callbacks. It is controlled through
1329 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
1331 If the notifier call chain should be failed with some events
1332 notified, write the error code to "actions/<notifier event>/error".
1334 Example: Inject CPU offline error (-1 == -EPERM)
1336 # cd /sys/kernel/debug/notifier-error-inject/cpu
1337 # echo -1 > actions/CPU_DOWN_PREPARE/error
1338 # echo 0 > /sys/devices/system/cpu/cpu1/online
1339 bash: echo: write error: Operation not permitted
1341 To compile this code as a module, choose M here: the module will
1342 be called cpu-notifier-error-inject.
1344 If unsure, say N.
1346 config PM_NOTIFIER_ERROR_INJECT
1347 tristate "PM notifier error injection module"
1348 depends on PM && NOTIFIER_ERROR_INJECTION
1349 default m if PM_DEBUG
1350 help
1351 This option provides the ability to inject artificial errors to
1352 PM notifier chain callbacks. It is controlled through debugfs
1353 interface /sys/kernel/debug/notifier-error-inject/pm
1355 If the notifier call chain should be failed with some events
1356 notified, write the error code to "actions/<notifier event>/error".
1358 Example: Inject PM suspend error (-12 = -ENOMEM)
1360 # cd /sys/kernel/debug/notifier-error-inject/pm/
1361 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1362 # echo mem > /sys/power/state
1363 bash: echo: write error: Cannot allocate memory
1365 To compile this code as a module, choose M here: the module will
1366 be called pm-notifier-error-inject.
1368 If unsure, say N.
1370 config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1371 tristate "OF reconfig notifier error injection module"
1372 depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1373 help
1374 This option provides the ability to inject artificial errors to
1375 OF reconfig notifier chain callbacks. It is controlled
1376 through debugfs interface under
1377 /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1379 If the notifier call chain should be failed with some events
1380 notified, write the error code to "actions/<notifier event>/error".
1382 To compile this code as a module, choose M here: the module will
1383 be called of-reconfig-notifier-error-inject.
1385 If unsure, say N.
1387 config FAULT_INJECTION
1388 bool "Fault-injection framework"
1389 depends on DEBUG_KERNEL
1390 help
1391 Provide fault-injection framework.
1392 For more details, see Documentation/fault-injection/.
1394 config FAILSLAB
1395 bool "Fault-injection capability for kmalloc"
1396 depends on FAULT_INJECTION
1397 depends on SLAB || SLUB
1398 help
1399 Provide fault-injection capability for kmalloc.
1401 config FAIL_PAGE_ALLOC
1402 bool "Fault-injection capabilitiy for alloc_pages()"
1403 depends on FAULT_INJECTION
1404 help
1405 Provide fault-injection capability for alloc_pages().
1407 config FAIL_MAKE_REQUEST
1408 bool "Fault-injection capability for disk IO"
1409 depends on FAULT_INJECTION && BLOCK
1410 help
1411 Provide fault-injection capability for disk IO.
1413 config FAIL_IO_TIMEOUT
1414 bool "Fault-injection capability for faking disk interrupts"
1415 depends on FAULT_INJECTION && BLOCK
1416 help
1417 Provide fault-injection capability on end IO handling. This
1418 will make the block layer "forget" an interrupt as configured,
1419 thus exercising the error handling.
1421 Only works with drivers that use the generic timeout handling,
1422 for others it wont do anything.
1424 config FAIL_MMC_REQUEST
1425 bool "Fault-injection capability for MMC IO"
1426 select DEBUG_FS
1427 depends on FAULT_INJECTION && MMC
1428 help
1429 Provide fault-injection capability for MMC IO.
1430 This will make the mmc core return data errors. This is
1431 useful to test the error handling in the mmc block device
1432 and to test how the mmc host driver handles retries from
1433 the block device.
1435 config FAULT_INJECTION_DEBUG_FS
1436 bool "Debugfs entries for fault-injection capabilities"
1437 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1438 help
1439 Enable configuration of fault-injection capabilities via debugfs.
1441 config FAULT_INJECTION_STACKTRACE_FILTER
1442 bool "stacktrace filter for fault-injection capabilities"
1443 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1444 depends on !X86_64
1445 select STACKTRACE
1446 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE
1447 help
1448 Provide stacktrace filter for fault-injection capabilities
1450 config LATENCYTOP
1451 bool "Latency measuring infrastructure"
1452 depends on HAVE_LATENCYTOP_SUPPORT
1453 depends on DEBUG_KERNEL
1454 depends on STACKTRACE_SUPPORT
1455 depends on PROC_FS
1456 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC
1457 select KALLSYMS
1458 select KALLSYMS_ALL
1459 select STACKTRACE
1460 select SCHEDSTATS
1461 select SCHED_DEBUG
1462 help
1463 Enable this option if you want to use the LatencyTOP tool
1464 to find out which userspace is blocking on what kernel operations.
1466 config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1467 bool
1469 config DEBUG_STRICT_USER_COPY_CHECKS
1470 bool "Strict user copy size checks"
1471 depends on ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1472 depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
1473 help
1474 Enabling this option turns a certain set of sanity checks for user
1475 copy operations into compile time failures.
1477 The copy_from_user() etc checks are there to help test if there
1478 are sufficient security checks on the length argument of
1479 the copy operation, by having gcc prove that the argument is
1480 within bounds.
1482 If unsure, say N.
1484 source kernel/trace/Kconfig
1486 menu "Runtime Testing"
1488 config LKDTM
1489 tristate "Linux Kernel Dump Test Tool Module"
1490 depends on DEBUG_FS
1491 depends on BLOCK
1492 default n
1493 help
1494 This module enables testing of the different dumping mechanisms by
1495 inducing system failures at predefined crash points.
1496 If you don't need it: say N
1497 Choose M here to compile this code as a module. The module will be
1498 called lkdtm.
1500 Documentation on how to use the module can be found in
1501 Documentation/fault-injection/provoke-crashes.txt
1503 config TEST_LIST_SORT
1504 bool "Linked list sorting test"
1505 depends on DEBUG_KERNEL
1506 help
1507 Enable this to turn on 'list_sort()' function test. This test is
1508 executed only once during system boot, so affects only boot time.
1510 If unsure, say N.
1512 config KPROBES_SANITY_TEST
1513 bool "Kprobes sanity tests"
1514 depends on DEBUG_KERNEL
1515 depends on KPROBES
1516 default n
1517 help
1518 This option provides for testing basic kprobes functionality on
1519 boot. A sample kprobe, jprobe and kretprobe are inserted and
1520 verified for functionality.
1522 Say N if you are unsure.
1524 config BACKTRACE_SELF_TEST
1525 tristate "Self test for the backtrace code"
1526 depends on DEBUG_KERNEL
1527 default n
1528 help
1529 This option provides a kernel module that can be used to test
1530 the kernel stack backtrace code. This option is not useful
1531 for distributions or general kernels, but only for kernel
1532 developers working on architecture code.
1534 Note that if you want to also test saved backtraces, you will
1535 have to enable STACKTRACE as well.
1537 Say N if you are unsure.
1539 config RBTREE_TEST
1540 tristate "Red-Black tree test"
1541 depends on DEBUG_KERNEL
1542 help
1543 A benchmark measuring the performance of the rbtree library.
1544 Also includes rbtree invariant checks.
1546 config INTERVAL_TREE_TEST
1547 tristate "Interval tree test"
1548 depends on m && DEBUG_KERNEL
1549 select INTERVAL_TREE
1550 help
1551 A benchmark measuring the performance of the interval tree library
1553 config PERCPU_TEST
1554 tristate "Per cpu operations test"
1555 depends on m && DEBUG_KERNEL
1556 help
1557 Enable this option to build test module which validates per-cpu
1558 operations.
1560 If unsure, say N.
1562 config ATOMIC64_SELFTEST
1563 bool "Perform an atomic64_t self-test at boot"
1564 help
1565 Enable this option to test the atomic64_t functions at boot.
1567 If unsure, say N.
1569 config ASYNC_RAID6_TEST
1570 tristate "Self test for hardware accelerated raid6 recovery"
1571 depends on ASYNC_RAID6_RECOV
1572 select ASYNC_MEMCPY
1573 ---help---
1574 This is a one-shot self test that permutes through the
1575 recovery of all the possible two disk failure scenarios for a
1576 N-disk array. Recovery is performed with the asynchronous
1577 raid6 recovery routines, and will optionally use an offload
1578 engine if one is available.
1580 If unsure, say N.
1582 config TEST_STRING_HELPERS
1583 tristate "Test functions located in the string_helpers module at runtime"
1585 config TEST_KSTRTOX
1586 tristate "Test kstrto*() family of functions at runtime"
1588 config TEST_RHASHTABLE
1589 bool "Perform selftest on resizable hash table"
1590 default n
1591 help
1592 Enable this option to test the rhashtable functions at boot.
1594 If unsure, say N.
1596 endmenu # runtime tests
1598 config PROVIDE_OHCI1394_DMA_INIT
1599 bool "Remote debugging over FireWire early on boot"
1600 depends on PCI && X86
1601 help
1602 If you want to debug problems which hang or crash the kernel early
1603 on boot and the crashing machine has a FireWire port, you can use
1604 this feature to remotely access the memory of the crashed machine
1605 over FireWire. This employs remote DMA as part of the OHCI1394
1606 specification which is now the standard for FireWire controllers.
1608 With remote DMA, you can monitor the printk buffer remotely using
1609 firescope and access all memory below 4GB using fireproxy from gdb.
1610 Even controlling a kernel debugger is possible using remote DMA.
1612 Usage:
1614 If ohci1394_dma=early is used as boot parameter, it will initialize
1615 all OHCI1394 controllers which are found in the PCI config space.
1617 As all changes to the FireWire bus such as enabling and disabling
1618 devices cause a bus reset and thereby disable remote DMA for all
1619 devices, be sure to have the cable plugged and FireWire enabled on
1620 the debugging host before booting the debug target for debugging.
1622 This code (~1k) is freed after boot. By then, the firewire stack
1623 in charge of the OHCI-1394 controllers should be used instead.
1625 See Documentation/debugging-via-ohci1394.txt for more information.
1627 config BUILD_DOCSRC
1628 bool "Build targets in Documentation/ tree"
1629 depends on HEADERS_CHECK
1630 help
1631 This option attempts to build objects from the source files in the
1632 kernel Documentation/ tree.
1634 Say N if you are unsure.
1636 config DMA_API_DEBUG
1637 bool "Enable debugging of DMA-API usage"
1638 depends on HAVE_DMA_API_DEBUG
1639 help
1640 Enable this option to debug the use of the DMA API by device drivers.
1641 With this option you will be able to detect common bugs in device
1642 drivers like double-freeing of DMA mappings or freeing mappings that
1643 were never allocated.
1645 This also attempts to catch cases where a page owned by DMA is
1646 accessed by the cpu in a way that could cause data corruption. For
1647 example, this enables cow_user_page() to check that the source page is
1648 not undergoing DMA.
1650 This option causes a performance degradation. Use only if you want to
1651 debug device drivers and dma interactions.
1653 If unsure, say N.
1655 config TEST_LKM
1656 tristate "Test module loading with 'hello world' module"
1657 default n
1658 depends on m
1659 help
1660 This builds the "test_module" module that emits "Hello, world"
1661 on printk when loaded. It is designed to be used for basic
1662 evaluation of the module loading subsystem (for example when
1663 validating module verification). It lacks any extra dependencies,
1664 and will not normally be loaded by the system unless explicitly
1665 requested by name.
1667 If unsure, say N.
1669 config TEST_USER_COPY
1670 tristate "Test user/kernel boundary protections"
1671 default n
1672 depends on m
1673 help
1674 This builds the "test_user_copy" module that runs sanity checks
1675 on the copy_to/from_user infrastructure, making sure basic
1676 user/kernel boundary testing is working. If it fails to load,
1677 a regression has been detected in the user/kernel memory boundary
1678 protections.
1680 If unsure, say N.
1682 config TEST_BPF
1683 tristate "Test BPF filter functionality"
1684 default n
1685 depends on m && NET
1686 help
1687 This builds the "test_bpf" module that runs various test vectors
1688 against the BPF interpreter or BPF JIT compiler depending on the
1689 current setting. This is in particular useful for BPF JIT compiler
1690 development, but also to run regression tests against changes in
1691 the interpreter code. It also enables test stubs for eBPF maps and
1692 verifier used by user space verifier testsuite.
1694 If unsure, say N.
1696 config TEST_FIRMWARE
1697 tristate "Test firmware loading via userspace interface"
1698 default n
1699 depends on FW_LOADER
1700 help
1701 This builds the "test_firmware" module that creates a userspace
1702 interface for testing firmware loading. This can be used to
1703 control the triggering of firmware loading without needing an
1704 actual firmware-using device. The contents can be rechecked by
1705 userspace.
1707 If unsure, say N.
1709 config TEST_UDELAY
1710 tristate "udelay test driver"
1711 default n
1712 help
1713 This builds the "udelay_test" module that helps to make sure
1714 that udelay() is working properly.
1716 If unsure, say N.
1718 source "samples/Kconfig"
1720 source "lib/Kconfig.kgdb"