xref: /openbmc/linux/lib/Kconfig.debug (revision 93d90ad7)
1menu "printk and dmesg options"
2
3config 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.
10
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.
14
15	  The behavior is also controlled by the kernel command line
16	  parameter printk.time=1. See Documentation/kernel-parameters.txt
17
18config 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.
24
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.
28
29config 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".
37
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.
46
47config DYNAMIC_DEBUG
48	bool "Enable dynamic printk() support"
49	default n
50	depends on PRINTK
51	depends on DEBUG_FS
52	help
53
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%.
60
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.
65
66	  Usage:
67
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:
74
75		filename:lineno [module]function flags format
76
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
83
84	  From a live system:
85
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"
91
92	  Example usage:
93
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
97
98		// enable all the messages in file svcsock.c
99		nullarbor:~ # echo -n 'file svcsock.c +p' >
100						<debugfs>/dynamic_debug/control
101
102		// enable all the messages in the NFS server module
103		nullarbor:~ # echo -n 'module nfsd +p' >
104						<debugfs>/dynamic_debug/control
105
106		// enable all 12 messages in the function svc_process()
107		nullarbor:~ # echo -n 'func svc_process +p' >
108						<debugfs>/dynamic_debug/control
109
110		// disable all 12 messages in the function svc_process()
111		nullarbor:~ # echo -n 'func svc_process -p' >
112						<debugfs>/dynamic_debug/control
113
114	  See Documentation/dynamic-debug-howto.txt for additional information.
115
116endmenu # "printk and dmesg options"
117
118menu "Compile-time checks and compiler options"
119
120config 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.
130
131	  If unsure, say N.
132
133config 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.
145
146config 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.
155
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.
160
161config 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.
169
170config 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.
177
178config 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.
185
186config 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
196
197config 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.
204
205config 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.
213
214config 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.
229
230config 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.
243
244	  If unsure, say N.
245
246config 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.
252
253	  For detailed documentation on the debugfs API, see
254	  Documentation/DocBook/filesystems.
255
256	  If unsure, say N.
257
258config 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.
266
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.
271
272config 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.
302
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#
308config ARCH_WANT_FRAME_POINTERS
309	bool
310	help
311
312config 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)
323
324config 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.
332
333	  1. percpu symbols must be unique whether static or not
334	  2. percpu variables can't be defined inside a function
335
336	  To ensure that generic code follows the above rules, this
337	  option forces all percpu variables to be defined as weak.
338
339endmenu # "Compiler options"
340
341config 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.
354
355config 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.
363
364config 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.
369
370menu "Memory Debugging"
371
372source mm/Kconfig.debug
373
374config 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.
381
382config 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.
387
388config 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.
396
397config 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.
404
405config 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.
412
413config 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).
418
419config 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.
426
427config 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
434
435config 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.
442
443config DEBUG_SLAB_LEAK
444	bool "Memory leak debugging"
445	depends on DEBUG_SLAB
446
447config 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=-".
459
460config 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
472
473config HAVE_DEBUG_KMEMLEAK
474	bool
475
476config 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.
492
493	  Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
494	  of finding leaks due to the slab objects poisoning.
495
496	  In order to access the kmemleak file, debugfs needs to be
497	  mounted (usually at /sys/kernel/debug).
498
499config 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.
510
511config 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.
516
517	  If unsure, say N.
518
519config 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.
525
526config 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.
532
533	  This option will slow down process creation somewhat.
534
535config 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.
541
542	  If unsure, say N.
543
544config 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.
551
552	  If unsure, say N.
553
554config 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.
559
560	  If unsure, say N.
561
562config 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.
568
569	  If unsure, say N.
570
571config 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.
577
578config 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.
587
588	  If unsure, say Y
589
590config 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
597
598	  If the notifier call chain should be failed with some events
599	  notified, write the error code to "actions/<notifier event>/error".
600
601	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
602
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
607
608	  To compile this code as a module, choose M here: the module will
609	  be called memory-notifier-error-inject.
610
611	  If unsure, say N.
612
613config 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.
621
622	  Say N if unsure.
623
624config 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.
630
631config HAVE_DEBUG_STACKOVERFLOW
632	bool
633
634config 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.
642
643	  These kinds of bugs usually occur when call-chains in the
644	  kernel get too deep, especially when interrupts are
645	  involved.
646
647	  Use this in cases where you see apparently random memory
648	  corruption, especially if it appears in 'struct thread_info'
649
650	  If in doubt, say "N".
651
652source "lib/Kconfig.kmemcheck"
653
654endmenu # "Memory Debugging"
655
656config 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.
664
665menu "Debug Lockups and Hangs"
666
667config 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.
673
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.
678
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.
683
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.
687
688	  The frequency of hrtimer and NMI events and the soft and hard lockup
689	  thresholds can be controlled through the sysctl watchdog_thresh.
690
691config HARDLOCKUP_DETECTOR
692	def_bool y
693	depends on LOCKUP_DETECTOR && !HAVE_NMI_WATCHDOG
694	depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI
695
696config 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).
704
705	  Say N if unsure.
706
707config 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
713
714config 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.
722
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.
728
729	  Say N if unsure.
730
731config 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
737
738config 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.
746
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.
752
753config 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.
761
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.
765
766	  A timeout of 0 disables the check.  The default is two minutes.
767	  Keeping the default should be fine in most cases.
768
769config 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.
776
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.
782
783	  Say N if unsure.
784
785config 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
791
792endmenu # "Debug lockups and hangs"
793
794config 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.
800
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.
804
805	  Say N if unsure.
806
807config PANIC_ON_OOPS_VALUE
808	int
809	range 0 1
810	default 0 if !PANIC_ON_OOPS
811	default 1 if PANIC_ON_OOPS
812
813config 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.
821
822config 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.
830
831config 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.
842
843config 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.
854
855config 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).
868
869config 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.
878
879menu "Lock Debugging (spinlocks, mutexes, etc...)"
880
881config 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.
887
888config 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.
893
894config 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.
903
904config 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.
910
911config 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.
927
928config 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.
941
942config 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.
959
960	 In short, this feature enables the kernel to report locking
961	 related deadlocks before they actually occur.
962
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).
972
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.
976
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.
982
983	 For more details, see Documentation/locking/lockdep-design.txt.
984
985config 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
992
993config 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
1003
1004	 For more details, see Documentation/locking/lockstat.txt
1005
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.
1010
1011	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1012	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1013
1014config 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.
1021
1022config 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...
1031
1032config 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.
1042
1043config 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.
1052
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.
1057
1058endmenu # lock debugging
1059
1060config TRACE_IRQFLAGS
1061	bool
1062	help
1063	  Enables hooks to interrupt enabling and disabling for
1064	  either tracing or lock debugging.
1065
1066config 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.
1074
1075config 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.
1081
1082config 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.
1092
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.
1096
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.
1100
1101config HAVE_DEBUG_BUGVERBOSE
1102	bool
1103
1104config 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.
1112
1113config 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.
1119
1120	  If unsure, say N.
1121
1122config 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.
1129
1130	  If unsure, say N.
1131
1132config 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.
1139
1140	  If unsure, say N.
1141
1142config 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.
1151
1152config 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.
1161
1162	  Furthermore, if SELinux is enabled, this also checks that the
1163	  security pointer in the cred struct is never seen to be invalid.
1164
1165	  If unsure, say N.
1166
1167menu "RCU Debugging"
1168
1169config 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.
1178
1179	 Say N if you are unsure.
1180
1181config 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.
1190
1191	 Say Y to allow multiple RCU-lockdep warnings per boot.
1192
1193	 Say N if you are unsure.
1194
1195config 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.
1205
1206	 Say Y to make sparse flag questionable use of RCU-protected pointers
1207
1208	 Say N if you are unsure.
1209
1210config TORTURE_TEST
1211	tristate
1212	default n
1213
1214config 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.
1223
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.
1228
1229config 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.
1240
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.
1245
1246config 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.
1256
1257config 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.
1266
1267	  Say N if you are unsure.
1268
1269	  Say Y if you want to enable such diagnostics.
1270
1271config 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.
1278
1279	  Say Y here if you want to enable RCU tracing
1280	  Say N if you are unsure.
1281
1282endmenu # "RCU Debugging"
1283
1284config 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.
1294
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.
1302
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.
1308
1309	  Say N if you are unsure.
1310
1311config 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.
1319
1320	  Say N if unsure.
1321
1322config 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
1330
1331	  If the notifier call chain should be failed with some events
1332	  notified, write the error code to "actions/<notifier event>/error".
1333
1334	  Example: Inject CPU offline error (-1 == -EPERM)
1335
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
1340
1341	  To compile this code as a module, choose M here: the module will
1342	  be called cpu-notifier-error-inject.
1343
1344	  If unsure, say N.
1345
1346config 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
1354
1355	  If the notifier call chain should be failed with some events
1356	  notified, write the error code to "actions/<notifier event>/error".
1357
1358	  Example: Inject PM suspend error (-12 = -ENOMEM)
1359
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
1364
1365	  To compile this code as a module, choose M here: the module will
1366	  be called pm-notifier-error-inject.
1367
1368	  If unsure, say N.
1369
1370config 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/
1378
1379	  If the notifier call chain should be failed with some events
1380	  notified, write the error code to "actions/<notifier event>/error".
1381
1382	  To compile this code as a module, choose M here: the module will
1383	  be called of-reconfig-notifier-error-inject.
1384
1385	  If unsure, say N.
1386
1387config 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/.
1393
1394config 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.
1400
1401config 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().
1406
1407config 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.
1412
1413config 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.
1420
1421	  Only works with drivers that use the generic timeout handling,
1422	  for others it wont do anything.
1423
1424config 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.
1434
1435config 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.
1440
1441config 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
1449
1450config 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.
1465
1466config ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
1467	bool
1468
1469config 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.
1476
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.
1481
1482	  If unsure, say N.
1483
1484source kernel/trace/Kconfig
1485
1486menu "Runtime Testing"
1487
1488config 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.
1499
1500	Documentation on how to use the module can be found in
1501	Documentation/fault-injection/provoke-crashes.txt
1502
1503config 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.
1509
1510	  If unsure, say N.
1511
1512config 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.
1521
1522	  Say N if you are unsure.
1523
1524config 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.
1533
1534	  Note that if you want to also test saved backtraces, you will
1535	  have to enable STACKTRACE as well.
1536
1537	  Say N if you are unsure.
1538
1539config 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.
1545
1546config 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
1552
1553config 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.
1559
1560	  If unsure, say N.
1561
1562config 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.
1566
1567	  If unsure, say N.
1568
1569config 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.
1579
1580	  If unsure, say N.
1581
1582config TEST_STRING_HELPERS
1583	tristate "Test functions located in the string_helpers module at runtime"
1584
1585config TEST_KSTRTOX
1586	tristate "Test kstrto*() family of functions at runtime"
1587
1588config 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.
1593
1594	  If unsure, say N.
1595
1596endmenu # runtime tests
1597
1598config 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.
1607
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.
1611
1612	  Usage:
1613
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.
1616
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.
1621
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.
1624
1625	  See Documentation/debugging-via-ohci1394.txt for more information.
1626
1627config 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.
1633
1634	  Say N if you are unsure.
1635
1636config 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.
1644
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.
1649
1650	  This option causes a performance degradation.  Use only if you want to
1651	  debug device drivers and dma interactions.
1652
1653	  If unsure, say N.
1654
1655config 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.
1666
1667	  If unsure, say N.
1668
1669config 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.
1679
1680	  If unsure, say N.
1681
1682config 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.
1693
1694	  If unsure, say N.
1695
1696config 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.
1706
1707	  If unsure, say N.
1708
1709config 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.
1715
1716	  If unsure, say N.
1717
1718source "samples/Kconfig"
1719
1720source "lib/Kconfig.kgdb"
1721
1722