xref: /openbmc/linux/lib/Kconfig.debug (revision c24c57a4)
1# SPDX-License-Identifier: GPL-2.0-only
2menu "Kernel hacking"
3
4menu "printk and dmesg options"
5
6config PRINTK_TIME
7	bool "Show timing information on printks"
8	depends on PRINTK
9	help
10	  Selecting this option causes time stamps of the printk()
11	  messages to be added to the output of the syslog() system
12	  call and at the console.
13
14	  The timestamp is always recorded internally, and exported
15	  to /dev/kmsg. This flag just specifies if the timestamp should
16	  be included, not that the timestamp is recorded.
17
18	  The behavior is also controlled by the kernel command line
19	  parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
20
21config PRINTK_CALLER
22	bool "Show caller information on printks"
23	depends on PRINTK
24	help
25	  Selecting this option causes printk() to add a caller "thread id" (if
26	  in task context) or a caller "processor id" (if not in task context)
27	  to every message.
28
29	  This option is intended for environments where multiple threads
30	  concurrently call printk() for many times, for it is difficult to
31	  interpret without knowing where these lines (or sometimes individual
32	  line which was divided into multiple lines due to race) came from.
33
34	  Since toggling after boot makes the code racy, currently there is
35	  no option to enable/disable at the kernel command line parameter or
36	  sysfs interface.
37
38config CONSOLE_LOGLEVEL_DEFAULT
39	int "Default console loglevel (1-15)"
40	range 1 15
41	default "7"
42	help
43	  Default loglevel to determine what will be printed on the console.
44
45	  Setting a default here is equivalent to passing in loglevel=<x> in
46	  the kernel bootargs. loglevel=<x> continues to override whatever
47	  value is specified here as well.
48
49	  Note: This does not affect the log level of un-prefixed printk()
50	  usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
51	  option.
52
53config CONSOLE_LOGLEVEL_QUIET
54	int "quiet console loglevel (1-15)"
55	range 1 15
56	default "4"
57	help
58	  loglevel to use when "quiet" is passed on the kernel commandline.
59
60	  When "quiet" is passed on the kernel commandline this loglevel
61	  will be used as the loglevel. IOW passing "quiet" will be the
62	  equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
63
64config MESSAGE_LOGLEVEL_DEFAULT
65	int "Default message log level (1-7)"
66	range 1 7
67	default "4"
68	help
69	  Default log level for printk statements with no specified priority.
70
71	  This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
72	  that are auditing their logs closely may want to set it to a lower
73	  priority.
74
75	  Note: This does not affect what message level gets printed on the console
76	  by default. To change that, use loglevel=<x> in the kernel bootargs,
77	  or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
78
79config BOOT_PRINTK_DELAY
80	bool "Delay each boot printk message by N milliseconds"
81	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
82	help
83	  This build option allows you to read kernel boot messages
84	  by inserting a short delay after each one.  The delay is
85	  specified in milliseconds on the kernel command line,
86	  using "boot_delay=N".
87
88	  It is likely that you would also need to use "lpj=M" to preset
89	  the "loops per jiffie" value.
90	  See a previous boot log for the "lpj" value to use for your
91	  system, and then set "lpj=M" before setting "boot_delay=N".
92	  NOTE:  Using this option may adversely affect SMP systems.
93	  I.e., processors other than the first one may not boot up.
94	  BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
95	  what it believes to be lockup conditions.
96
97config DYNAMIC_DEBUG
98	bool "Enable dynamic printk() support"
99	default n
100	depends on PRINTK
101	depends on DEBUG_FS
102	help
103
104	  Compiles debug level messages into the kernel, which would not
105	  otherwise be available at runtime. These messages can then be
106	  enabled/disabled based on various levels of scope - per source file,
107	  function, module, format string, and line number. This mechanism
108	  implicitly compiles in all pr_debug() and dev_dbg() calls, which
109	  enlarges the kernel text size by about 2%.
110
111	  If a source file is compiled with DEBUG flag set, any
112	  pr_debug() calls in it are enabled by default, but can be
113	  disabled at runtime as below.  Note that DEBUG flag is
114	  turned on by many CONFIG_*DEBUG* options.
115
116	  Usage:
117
118	  Dynamic debugging is controlled via the 'dynamic_debug/control' file,
119	  which is contained in the 'debugfs' filesystem. Thus, the debugfs
120	  filesystem must first be mounted before making use of this feature.
121	  We refer the control file as: <debugfs>/dynamic_debug/control. This
122	  file contains a list of the debug statements that can be enabled. The
123	  format for each line of the file is:
124
125		filename:lineno [module]function flags format
126
127	  filename : source file of the debug statement
128	  lineno : line number of the debug statement
129	  module : module that contains the debug statement
130	  function : function that contains the debug statement
131          flags : '=p' means the line is turned 'on' for printing
132          format : the format used for the debug statement
133
134	  From a live system:
135
136		nullarbor:~ # cat <debugfs>/dynamic_debug/control
137		# filename:lineno [module]function flags format
138		fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
139		fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
140		fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
141
142	  Example usage:
143
144		// enable the message at line 1603 of file svcsock.c
145		nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
146						<debugfs>/dynamic_debug/control
147
148		// enable all the messages in file svcsock.c
149		nullarbor:~ # echo -n 'file svcsock.c +p' >
150						<debugfs>/dynamic_debug/control
151
152		// enable all the messages in the NFS server module
153		nullarbor:~ # echo -n 'module nfsd +p' >
154						<debugfs>/dynamic_debug/control
155
156		// enable all 12 messages in the function svc_process()
157		nullarbor:~ # echo -n 'func svc_process +p' >
158						<debugfs>/dynamic_debug/control
159
160		// disable all 12 messages in the function svc_process()
161		nullarbor:~ # echo -n 'func svc_process -p' >
162						<debugfs>/dynamic_debug/control
163
164	  See Documentation/admin-guide/dynamic-debug-howto.rst for additional
165	  information.
166
167config SYMBOLIC_ERRNAME
168	bool "Support symbolic error names in printf"
169	default y if PRINTK
170	help
171	  If you say Y here, the kernel's printf implementation will
172	  be able to print symbolic error names such as ENOSPC instead
173	  of the number 28. It makes the kernel image slightly larger
174	  (about 3KB), but can make the kernel logs easier to read.
175
176endmenu # "printk and dmesg options"
177
178menu "Compile-time checks and compiler options"
179
180config DEBUG_INFO
181	bool "Compile the kernel with debug info"
182	depends on DEBUG_KERNEL && !COMPILE_TEST
183	help
184          If you say Y here the resulting kernel image will include
185	  debugging info resulting in a larger kernel image.
186	  This adds debug symbols to the kernel and modules (gcc -g), and
187	  is needed if you intend to use kernel crashdump or binary object
188	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
189	  Say Y here only if you plan to debug the kernel.
190
191	  If unsure, say N.
192
193config DEBUG_INFO_REDUCED
194	bool "Reduce debugging information"
195	depends on DEBUG_INFO
196	help
197	  If you say Y here gcc is instructed to generate less debugging
198	  information for structure types. This means that tools that
199	  need full debugging information (like kgdb or systemtap) won't
200	  be happy. But if you merely need debugging information to
201	  resolve line numbers there is no loss. Advantage is that
202	  build directory object sizes shrink dramatically over a full
203	  DEBUG_INFO build and compile times are reduced too.
204	  Only works with newer gcc versions.
205
206config DEBUG_INFO_SPLIT
207	bool "Produce split debuginfo in .dwo files"
208	depends on DEBUG_INFO
209	depends on $(cc-option,-gsplit-dwarf)
210	help
211	  Generate debug info into separate .dwo files. This significantly
212	  reduces the build directory size for builds with DEBUG_INFO,
213	  because it stores the information only once on disk in .dwo
214	  files instead of multiple times in object files and executables.
215	  In addition the debug information is also compressed.
216
217	  Requires recent gcc (4.7+) and recent gdb/binutils.
218	  Any tool that packages or reads debug information would need
219	  to know about the .dwo files and include them.
220	  Incompatible with older versions of ccache.
221
222config DEBUG_INFO_DWARF4
223	bool "Generate dwarf4 debuginfo"
224	depends on DEBUG_INFO
225	depends on $(cc-option,-gdwarf-4)
226	help
227	  Generate dwarf4 debug info. This requires recent versions
228	  of gcc and gdb. It makes the debug information larger.
229	  But it significantly improves the success of resolving
230	  variables in gdb on optimized code.
231
232config DEBUG_INFO_BTF
233	bool "Generate BTF typeinfo"
234	depends on DEBUG_INFO
235	help
236	  Generate deduplicated BTF type information from DWARF debug info.
237	  Turning this on expects presence of pahole tool, which will convert
238	  DWARF type info into equivalent deduplicated BTF type info.
239
240config GDB_SCRIPTS
241	bool "Provide GDB scripts for kernel debugging"
242	depends on DEBUG_INFO
243	help
244	  This creates the required links to GDB helper scripts in the
245	  build directory. If you load vmlinux into gdb, the helper
246	  scripts will be automatically imported by gdb as well, and
247	  additional functions are available to analyze a Linux kernel
248	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
249	  for further details.
250
251config ENABLE_MUST_CHECK
252	bool "Enable __must_check logic"
253	default y
254	help
255	  Enable the __must_check logic in the kernel build.  Disable this to
256	  suppress the "warning: ignoring return value of 'foo', declared with
257	  attribute warn_unused_result" messages.
258
259config FRAME_WARN
260	int "Warn for stack frames larger than (needs gcc 4.4)"
261	range 0 8192
262	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
263	default 1280 if (!64BIT && PARISC)
264	default 1024 if (!64BIT && !PARISC)
265	default 2048 if 64BIT
266	help
267	  Tell gcc to warn at build time for stack frames larger than this.
268	  Setting this too low will cause a lot of warnings.
269	  Setting it to 0 disables the warning.
270	  Requires gcc 4.4
271
272config STRIP_ASM_SYMS
273	bool "Strip assembler-generated symbols during link"
274	default n
275	help
276	  Strip internal assembler-generated symbols during a link (symbols
277	  that look like '.Lxxx') so they don't pollute the output of
278	  get_wchan() and suchlike.
279
280config READABLE_ASM
281        bool "Generate readable assembler code"
282        depends on DEBUG_KERNEL
283        help
284          Disable some compiler optimizations that tend to generate human unreadable
285          assembler output. This may make the kernel slightly slower, but it helps
286          to keep kernel developers who have to stare a lot at assembler listings
287          sane.
288
289config DEBUG_FS
290	bool "Debug Filesystem"
291	help
292	  debugfs is a virtual file system that kernel developers use to put
293	  debugging files into.  Enable this option to be able to read and
294	  write to these files.
295
296	  For detailed documentation on the debugfs API, see
297	  Documentation/filesystems/.
298
299	  If unsure, say N.
300
301config HEADERS_INSTALL
302	bool "Install uapi headers to usr/include"
303	depends on !UML
304	help
305	  This option will install uapi headers (headers exported to user-space)
306	  into the usr/include directory for use during the kernel build.
307	  This is unneeded for building the kernel itself, but needed for some
308	  user-space program samples. It is also needed by some features such
309	  as uapi header sanity checks.
310
311config HEADERS_CHECK
312	bool "Run sanity checks on uapi headers when building 'all'"
313	depends on HEADERS_INSTALL
314	help
315	  This option will run basic sanity checks on uapi headers when
316	  building the 'all' target, for example, ensure that they do not
317	  attempt to include files which were not exported, etc.
318
319	  If you're making modifications to header files which are
320	  relevant for userspace, say 'Y'.
321
322config OPTIMIZE_INLINING
323	def_bool y
324	help
325	  This option determines if the kernel forces gcc to inline the functions
326	  developers have marked 'inline'. Doing so takes away freedom from gcc to
327	  do what it thinks is best, which is desirable for the gcc 3.x series of
328	  compilers. The gcc 4.x series have a rewritten inlining algorithm and
329	  enabling this option will generate a smaller kernel there. Hopefully
330	  this algorithm is so good that allowing gcc 4.x and above to make the
331	  decision will become the default in the future. Until then this option
332	  is there to test gcc for this.
333
334config DEBUG_SECTION_MISMATCH
335	bool "Enable full Section mismatch analysis"
336	help
337	  The section mismatch analysis checks if there are illegal
338	  references from one section to another section.
339	  During linktime or runtime, some sections are dropped;
340	  any use of code/data previously in these sections would
341	  most likely result in an oops.
342	  In the code, functions and variables are annotated with
343	  __init,, etc. (see the full list in include/linux/init.h),
344	  which results in the code/data being placed in specific sections.
345	  The section mismatch analysis is always performed after a full
346	  kernel build, and enabling this option causes the following
347	  additional step to occur:
348	  - Add the option -fno-inline-functions-called-once to gcc commands.
349	    When inlining a function annotated with __init in a non-init
350	    function, we would lose the section information and thus
351	    the analysis would not catch the illegal reference.
352	    This option tells gcc to inline less (but it does result in
353	    a larger kernel).
354
355config SECTION_MISMATCH_WARN_ONLY
356	bool "Make section mismatch errors non-fatal"
357	default y
358	help
359	  If you say N here, the build process will fail if there are any
360	  section mismatch, instead of just throwing warnings.
361
362	  If unsure, say Y.
363
364#
365# Select this config option from the architecture Kconfig, if it
366# is preferred to always offer frame pointers as a config
367# option on the architecture (regardless of KERNEL_DEBUG):
368#
369config ARCH_WANT_FRAME_POINTERS
370	bool
371
372config FRAME_POINTER
373	bool "Compile the kernel with frame pointers"
374	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
375	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
376	help
377	  If you say Y here the resulting kernel image will be slightly
378	  larger and slower, but it gives very useful debugging information
379	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
380
381config STACK_VALIDATION
382	bool "Compile-time stack metadata validation"
383	depends on HAVE_STACK_VALIDATION
384	default n
385	help
386	  Add compile-time checks to validate stack metadata, including frame
387	  pointers (if CONFIG_FRAME_POINTER is enabled).  This helps ensure
388	  that runtime stack traces are more reliable.
389
390	  This is also a prerequisite for generation of ORC unwind data, which
391	  is needed for CONFIG_UNWINDER_ORC.
392
393	  For more information, see
394	  tools/objtool/Documentation/stack-validation.txt.
395
396config DEBUG_FORCE_WEAK_PER_CPU
397	bool "Force weak per-cpu definitions"
398	depends on DEBUG_KERNEL
399	help
400	  s390 and alpha require percpu variables in modules to be
401	  defined weak to work around addressing range issue which
402	  puts the following two restrictions on percpu variable
403	  definitions.
404
405	  1. percpu symbols must be unique whether static or not
406	  2. percpu variables can't be defined inside a function
407
408	  To ensure that generic code follows the above rules, this
409	  option forces all percpu variables to be defined as weak.
410
411endmenu # "Compiler options"
412
413config MAGIC_SYSRQ
414	bool "Magic SysRq key"
415	depends on !UML
416	help
417	  If you say Y here, you will have some control over the system even
418	  if the system crashes for example during kernel debugging (e.g., you
419	  will be able to flush the buffer cache to disk, reboot the system
420	  immediately or dump some status information). This is accomplished
421	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
422	  also works on a serial console (on PC hardware at least), if you
423	  send a BREAK and then within 5 seconds a command keypress. The
424	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
425	  Don't say Y unless you really know what this hack does.
426
427config MAGIC_SYSRQ_DEFAULT_ENABLE
428	hex "Enable magic SysRq key functions by default"
429	depends on MAGIC_SYSRQ
430	default 0x1
431	help
432	  Specifies which SysRq key functions are enabled by default.
433	  This may be set to 1 or 0 to enable or disable them all, or
434	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
435
436config MAGIC_SYSRQ_SERIAL
437	bool "Enable magic SysRq key over serial"
438	depends on MAGIC_SYSRQ
439	default y
440	help
441	  Many embedded boards have a disconnected TTL level serial which can
442	  generate some garbage that can lead to spurious false sysrq detects.
443	  This option allows you to decide whether you want to enable the
444	  magic SysRq key.
445
446config DEBUG_KERNEL
447	bool "Kernel debugging"
448	help
449	  Say Y here if you are developing drivers or trying to debug and
450	  identify kernel problems.
451
452config DEBUG_MISC
453	bool "Miscellaneous debug code"
454	default DEBUG_KERNEL
455	depends on DEBUG_KERNEL
456	help
457	  Say Y here if you need to enable miscellaneous debug code that should
458	  be under a more specific debug option but isn't.
459
460
461menu "Memory Debugging"
462
463source "mm/Kconfig.debug"
464
465config DEBUG_OBJECTS
466	bool "Debug object operations"
467	depends on DEBUG_KERNEL
468	help
469	  If you say Y here, additional code will be inserted into the
470	  kernel to track the life time of various objects and validate
471	  the operations on those objects.
472
473config DEBUG_OBJECTS_SELFTEST
474	bool "Debug objects selftest"
475	depends on DEBUG_OBJECTS
476	help
477	  This enables the selftest of the object debug code.
478
479config DEBUG_OBJECTS_FREE
480	bool "Debug objects in freed memory"
481	depends on DEBUG_OBJECTS
482	help
483	  This enables checks whether a k/v free operation frees an area
484	  which contains an object which has not been deactivated
485	  properly. This can make kmalloc/kfree-intensive workloads
486	  much slower.
487
488config DEBUG_OBJECTS_TIMERS
489	bool "Debug timer objects"
490	depends on DEBUG_OBJECTS
491	help
492	  If you say Y here, additional code will be inserted into the
493	  timer routines to track the life time of timer objects and
494	  validate the timer operations.
495
496config DEBUG_OBJECTS_WORK
497	bool "Debug work objects"
498	depends on DEBUG_OBJECTS
499	help
500	  If you say Y here, additional code will be inserted into the
501	  work queue routines to track the life time of work objects and
502	  validate the work operations.
503
504config DEBUG_OBJECTS_RCU_HEAD
505	bool "Debug RCU callbacks objects"
506	depends on DEBUG_OBJECTS
507	help
508	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
509
510config DEBUG_OBJECTS_PERCPU_COUNTER
511	bool "Debug percpu counter objects"
512	depends on DEBUG_OBJECTS
513	help
514	  If you say Y here, additional code will be inserted into the
515	  percpu counter routines to track the life time of percpu counter
516	  objects and validate the percpu counter operations.
517
518config DEBUG_OBJECTS_ENABLE_DEFAULT
519	int "debug_objects bootup default value (0-1)"
520        range 0 1
521        default "1"
522        depends on DEBUG_OBJECTS
523        help
524          Debug objects boot parameter default value
525
526config DEBUG_SLAB
527	bool "Debug slab memory allocations"
528	depends on DEBUG_KERNEL && SLAB
529	help
530	  Say Y here to have the kernel do limited verification on memory
531	  allocation as well as poisoning memory on free to catch use of freed
532	  memory. This can make kmalloc/kfree-intensive workloads much slower.
533
534config SLUB_DEBUG_ON
535	bool "SLUB debugging on by default"
536	depends on SLUB && SLUB_DEBUG
537	default n
538	help
539	  Boot with debugging on by default. SLUB boots by default with
540	  the runtime debug capabilities switched off. Enabling this is
541	  equivalent to specifying the "slub_debug" parameter on boot.
542	  There is no support for more fine grained debug control like
543	  possible with slub_debug=xxx. SLUB debugging may be switched
544	  off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
545	  "slub_debug=-".
546
547config SLUB_STATS
548	default n
549	bool "Enable SLUB performance statistics"
550	depends on SLUB && SYSFS
551	help
552	  SLUB statistics are useful to debug SLUBs allocation behavior in
553	  order find ways to optimize the allocator. This should never be
554	  enabled for production use since keeping statistics slows down
555	  the allocator by a few percentage points. The slabinfo command
556	  supports the determination of the most active slabs to figure
557	  out which slabs are relevant to a particular load.
558	  Try running: slabinfo -DA
559
560config HAVE_DEBUG_KMEMLEAK
561	bool
562
563config DEBUG_KMEMLEAK
564	bool "Kernel memory leak detector"
565	depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
566	select DEBUG_FS
567	select STACKTRACE if STACKTRACE_SUPPORT
568	select KALLSYMS
569	select CRC32
570	help
571	  Say Y here if you want to enable the memory leak
572	  detector. The memory allocation/freeing is traced in a way
573	  similar to the Boehm's conservative garbage collector, the
574	  difference being that the orphan objects are not freed but
575	  only shown in /sys/kernel/debug/kmemleak. Enabling this
576	  feature will introduce an overhead to memory
577	  allocations. See Documentation/dev-tools/kmemleak.rst for more
578	  details.
579
580	  Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
581	  of finding leaks due to the slab objects poisoning.
582
583	  In order to access the kmemleak file, debugfs needs to be
584	  mounted (usually at /sys/kernel/debug).
585
586config DEBUG_KMEMLEAK_MEM_POOL_SIZE
587	int "Kmemleak memory pool size"
588	depends on DEBUG_KMEMLEAK
589	range 200 1000000
590	default 16000
591	help
592	  Kmemleak must track all the memory allocations to avoid
593	  reporting false positives. Since memory may be allocated or
594	  freed before kmemleak is fully initialised, use a static pool
595	  of metadata objects to track such callbacks. After kmemleak is
596	  fully initialised, this memory pool acts as an emergency one
597	  if slab allocations fail.
598
599config DEBUG_KMEMLEAK_TEST
600	tristate "Simple test for the kernel memory leak detector"
601	depends on DEBUG_KMEMLEAK && m
602	help
603	  This option enables a module that explicitly leaks memory.
604
605	  If unsure, say N.
606
607config DEBUG_KMEMLEAK_DEFAULT_OFF
608	bool "Default kmemleak to off"
609	depends on DEBUG_KMEMLEAK
610	help
611	  Say Y here to disable kmemleak by default. It can then be enabled
612	  on the command line via kmemleak=on.
613
614config DEBUG_KMEMLEAK_AUTO_SCAN
615	bool "Enable kmemleak auto scan thread on boot up"
616	default y
617	depends on DEBUG_KMEMLEAK
618	help
619	  Depending on the cpu, kmemleak scan may be cpu intensive and can
620	  stall user tasks at times. This option enables/disables automatic
621	  kmemleak scan at boot up.
622
623	  Say N here to disable kmemleak auto scan thread to stop automatic
624	  scanning. Disabling this option disables automatic reporting of
625	  memory leaks.
626
627	  If unsure, say Y.
628
629config DEBUG_STACK_USAGE
630	bool "Stack utilization instrumentation"
631	depends on DEBUG_KERNEL && !IA64
632	help
633	  Enables the display of the minimum amount of free stack which each
634	  task has ever had available in the sysrq-T and sysrq-P debug output.
635
636	  This option will slow down process creation somewhat.
637
638config DEBUG_VM
639	bool "Debug VM"
640	depends on DEBUG_KERNEL
641	help
642	  Enable this to turn on extended checks in the virtual-memory system
643          that may impact performance.
644
645	  If unsure, say N.
646
647config DEBUG_VM_VMACACHE
648	bool "Debug VMA caching"
649	depends on DEBUG_VM
650	help
651	  Enable this to turn on VMA caching debug information. Doing so
652	  can cause significant overhead, so only enable it in non-production
653	  environments.
654
655	  If unsure, say N.
656
657config DEBUG_VM_RB
658	bool "Debug VM red-black trees"
659	depends on DEBUG_VM
660	help
661	  Enable VM red-black tree debugging information and extra validations.
662
663	  If unsure, say N.
664
665config DEBUG_VM_PGFLAGS
666	bool "Debug page-flags operations"
667	depends on DEBUG_VM
668	help
669	  Enables extra validation on page flags operations.
670
671	  If unsure, say N.
672
673config ARCH_HAS_DEBUG_VIRTUAL
674	bool
675
676config DEBUG_VIRTUAL
677	bool "Debug VM translations"
678	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
679	help
680	  Enable some costly sanity checks in virtual to page code. This can
681	  catch mistakes with virt_to_page() and friends.
682
683	  If unsure, say N.
684
685config DEBUG_NOMMU_REGIONS
686	bool "Debug the global anon/private NOMMU mapping region tree"
687	depends on DEBUG_KERNEL && !MMU
688	help
689	  This option causes the global tree of anonymous and private mapping
690	  regions to be regularly checked for invalid topology.
691
692config DEBUG_MEMORY_INIT
693	bool "Debug memory initialisation" if EXPERT
694	default !EXPERT
695	help
696	  Enable this for additional checks during memory initialisation.
697	  The sanity checks verify aspects of the VM such as the memory model
698	  and other information provided by the architecture. Verbose
699	  information will be printed at KERN_DEBUG loglevel depending
700	  on the mminit_loglevel= command-line option.
701
702	  If unsure, say Y
703
704config MEMORY_NOTIFIER_ERROR_INJECT
705	tristate "Memory hotplug notifier error injection module"
706	depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
707	help
708	  This option provides the ability to inject artificial errors to
709	  memory hotplug notifier chain callbacks.  It is controlled through
710	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
711
712	  If the notifier call chain should be failed with some events
713	  notified, write the error code to "actions/<notifier event>/error".
714
715	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
716
717	  # cd /sys/kernel/debug/notifier-error-inject/memory
718	  # echo -12 > actions/MEM_GOING_OFFLINE/error
719	  # echo offline > /sys/devices/system/memory/memoryXXX/state
720	  bash: echo: write error: Cannot allocate memory
721
722	  To compile this code as a module, choose M here: the module will
723	  be called memory-notifier-error-inject.
724
725	  If unsure, say N.
726
727config DEBUG_PER_CPU_MAPS
728	bool "Debug access to per_cpu maps"
729	depends on DEBUG_KERNEL
730	depends on SMP
731	help
732	  Say Y to verify that the per_cpu map being accessed has
733	  been set up. This adds a fair amount of code to kernel memory
734	  and decreases performance.
735
736	  Say N if unsure.
737
738config DEBUG_HIGHMEM
739	bool "Highmem debugging"
740	depends on DEBUG_KERNEL && HIGHMEM
741	help
742	  This option enables additional error checking for high memory
743	  systems.  Disable for production systems.
744
745config HAVE_DEBUG_STACKOVERFLOW
746	bool
747
748config DEBUG_STACKOVERFLOW
749	bool "Check for stack overflows"
750	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
751	---help---
752	  Say Y here if you want to check for overflows of kernel, IRQ
753	  and exception stacks (if your architecture uses them). This
754	  option will show detailed messages if free stack space drops
755	  below a certain limit.
756
757	  These kinds of bugs usually occur when call-chains in the
758	  kernel get too deep, especially when interrupts are
759	  involved.
760
761	  Use this in cases where you see apparently random memory
762	  corruption, especially if it appears in 'struct thread_info'
763
764	  If in doubt, say "N".
765
766source "lib/Kconfig.kasan"
767
768endmenu # "Memory Debugging"
769
770config ARCH_HAS_KCOV
771	bool
772	help
773	  An architecture should select this when it can successfully
774	  build and run with CONFIG_KCOV. This typically requires
775	  disabling instrumentation for some early boot code.
776
777config CC_HAS_SANCOV_TRACE_PC
778	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
779
780config KCOV
781	bool "Code coverage for fuzzing"
782	depends on ARCH_HAS_KCOV
783	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
784	select DEBUG_FS
785	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
786	help
787	  KCOV exposes kernel code coverage information in a form suitable
788	  for coverage-guided fuzzing (randomized testing).
789
790	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
791	  different machines and across reboots. If you need stable PC values,
792	  disable RANDOMIZE_BASE.
793
794	  For more details, see Documentation/dev-tools/kcov.rst.
795
796config KCOV_ENABLE_COMPARISONS
797	bool "Enable comparison operands collection by KCOV"
798	depends on KCOV
799	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
800	help
801	  KCOV also exposes operands of every comparison in the instrumented
802	  code along with operand sizes and PCs of the comparison instructions.
803	  These operands can be used by fuzzing engines to improve the quality
804	  of fuzzing coverage.
805
806config KCOV_INSTRUMENT_ALL
807	bool "Instrument all code by default"
808	depends on KCOV
809	default y
810	help
811	  If you are doing generic system call fuzzing (like e.g. syzkaller),
812	  then you will want to instrument the whole kernel and you should
813	  say y here. If you are doing more targeted fuzzing (like e.g.
814	  filesystem fuzzing with AFL) then you will want to enable coverage
815	  for more specific subsets of files, and should say n here.
816
817config DEBUG_SHIRQ
818	bool "Debug shared IRQ handlers"
819	depends on DEBUG_KERNEL
820	help
821	  Enable this to generate a spurious interrupt as soon as a shared
822	  interrupt handler is registered, and just before one is deregistered.
823	  Drivers ought to be able to handle interrupts coming in at those
824	  points; some don't and need to be caught.
825
826menu "Debug Lockups and Hangs"
827
828config LOCKUP_DETECTOR
829	bool
830
831config SOFTLOCKUP_DETECTOR
832	bool "Detect Soft Lockups"
833	depends on DEBUG_KERNEL && !S390
834	select LOCKUP_DETECTOR
835	help
836	  Say Y here to enable the kernel to act as a watchdog to detect
837	  soft lockups.
838
839	  Softlockups are bugs that cause the kernel to loop in kernel
840	  mode for more than 20 seconds, without giving other tasks a
841	  chance to run.  The current stack trace is displayed upon
842	  detection and the system will stay locked up.
843
844config BOOTPARAM_SOFTLOCKUP_PANIC
845	bool "Panic (Reboot) On Soft Lockups"
846	depends on SOFTLOCKUP_DETECTOR
847	help
848	  Say Y here to enable the kernel to panic on "soft lockups",
849	  which are bugs that cause the kernel to loop in kernel
850	  mode for more than 20 seconds (configurable using the watchdog_thresh
851	  sysctl), without giving other tasks a chance to run.
852
853	  The panic can be used in combination with panic_timeout,
854	  to cause the system to reboot automatically after a
855	  lockup has been detected. This feature is useful for
856	  high-availability systems that have uptime guarantees and
857	  where a lockup must be resolved ASAP.
858
859	  Say N if unsure.
860
861config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
862	int
863	depends on SOFTLOCKUP_DETECTOR
864	range 0 1
865	default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
866	default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
867
868config HARDLOCKUP_DETECTOR_PERF
869	bool
870	select SOFTLOCKUP_DETECTOR
871
872#
873# Enables a timestamp based low pass filter to compensate for perf based
874# hard lockup detection which runs too fast due to turbo modes.
875#
876config HARDLOCKUP_CHECK_TIMESTAMP
877	bool
878
879#
880# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
881# lockup detector rather than the perf based detector.
882#
883config HARDLOCKUP_DETECTOR
884	bool "Detect Hard Lockups"
885	depends on DEBUG_KERNEL && !S390
886	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
887	select LOCKUP_DETECTOR
888	select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
889	select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
890	help
891	  Say Y here to enable the kernel to act as a watchdog to detect
892	  hard lockups.
893
894	  Hardlockups are bugs that cause the CPU to loop in kernel mode
895	  for more than 10 seconds, without letting other interrupts have a
896	  chance to run.  The current stack trace is displayed upon detection
897	  and the system will stay locked up.
898
899config BOOTPARAM_HARDLOCKUP_PANIC
900	bool "Panic (Reboot) On Hard Lockups"
901	depends on HARDLOCKUP_DETECTOR
902	help
903	  Say Y here to enable the kernel to panic on "hard lockups",
904	  which are bugs that cause the kernel to loop in kernel
905	  mode with interrupts disabled for more than 10 seconds (configurable
906	  using the watchdog_thresh sysctl).
907
908	  Say N if unsure.
909
910config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
911	int
912	depends on HARDLOCKUP_DETECTOR
913	range 0 1
914	default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
915	default 1 if BOOTPARAM_HARDLOCKUP_PANIC
916
917config DETECT_HUNG_TASK
918	bool "Detect Hung Tasks"
919	depends on DEBUG_KERNEL
920	default SOFTLOCKUP_DETECTOR
921	help
922	  Say Y here to enable the kernel to detect "hung tasks",
923	  which are bugs that cause the task to be stuck in
924	  uninterruptible "D" state indefinitely.
925
926	  When a hung task is detected, the kernel will print the
927	  current stack trace (which you should report), but the
928	  task will stay in uninterruptible state. If lockdep is
929	  enabled then all held locks will also be reported. This
930	  feature has negligible overhead.
931
932config DEFAULT_HUNG_TASK_TIMEOUT
933	int "Default timeout for hung task detection (in seconds)"
934	depends on DETECT_HUNG_TASK
935	default 120
936	help
937	  This option controls the default timeout (in seconds) used
938	  to determine when a task has become non-responsive and should
939	  be considered hung.
940
941	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
942	  sysctl or by writing a value to
943	  /proc/sys/kernel/hung_task_timeout_secs.
944
945	  A timeout of 0 disables the check.  The default is two minutes.
946	  Keeping the default should be fine in most cases.
947
948config BOOTPARAM_HUNG_TASK_PANIC
949	bool "Panic (Reboot) On Hung Tasks"
950	depends on DETECT_HUNG_TASK
951	help
952	  Say Y here to enable the kernel to panic on "hung tasks",
953	  which are bugs that cause the kernel to leave a task stuck
954	  in uninterruptible "D" state.
955
956	  The panic can be used in combination with panic_timeout,
957	  to cause the system to reboot automatically after a
958	  hung task has been detected. This feature is useful for
959	  high-availability systems that have uptime guarantees and
960	  where a hung tasks must be resolved ASAP.
961
962	  Say N if unsure.
963
964config BOOTPARAM_HUNG_TASK_PANIC_VALUE
965	int
966	depends on DETECT_HUNG_TASK
967	range 0 1
968	default 0 if !BOOTPARAM_HUNG_TASK_PANIC
969	default 1 if BOOTPARAM_HUNG_TASK_PANIC
970
971config WQ_WATCHDOG
972	bool "Detect Workqueue Stalls"
973	depends on DEBUG_KERNEL
974	help
975	  Say Y here to enable stall detection on workqueues.  If a
976	  worker pool doesn't make forward progress on a pending work
977	  item for over a given amount of time, 30s by default, a
978	  warning message is printed along with dump of workqueue
979	  state.  This can be configured through kernel parameter
980	  "workqueue.watchdog_thresh" and its sysfs counterpart.
981
982endmenu # "Debug lockups and hangs"
983
984config PANIC_ON_OOPS
985	bool "Panic on Oops"
986	help
987	  Say Y here to enable the kernel to panic when it oopses. This
988	  has the same effect as setting oops=panic on the kernel command
989	  line.
990
991	  This feature is useful to ensure that the kernel does not do
992	  anything erroneous after an oops which could result in data
993	  corruption or other issues.
994
995	  Say N if unsure.
996
997config PANIC_ON_OOPS_VALUE
998	int
999	range 0 1
1000	default 0 if !PANIC_ON_OOPS
1001	default 1 if PANIC_ON_OOPS
1002
1003config PANIC_TIMEOUT
1004	int "panic timeout"
1005	default 0
1006	help
1007	  Set the timeout value (in seconds) until a reboot occurs when the
1008	  the kernel panics. If n = 0, then we wait forever. A timeout
1009	  value n > 0 will wait n seconds before rebooting, while a timeout
1010	  value n < 0 will reboot immediately.
1011
1012config SCHED_DEBUG
1013	bool "Collect scheduler debugging info"
1014	depends on DEBUG_KERNEL && PROC_FS
1015	default y
1016	help
1017	  If you say Y here, the /proc/sched_debug file will be provided
1018	  that can help debug the scheduler. The runtime overhead of this
1019	  option is minimal.
1020
1021config SCHED_INFO
1022	bool
1023	default n
1024
1025config SCHEDSTATS
1026	bool "Collect scheduler statistics"
1027	depends on DEBUG_KERNEL && PROC_FS
1028	select SCHED_INFO
1029	help
1030	  If you say Y here, additional code will be inserted into the
1031	  scheduler and related routines to collect statistics about
1032	  scheduler behavior and provide them in /proc/schedstat.  These
1033	  stats may be useful for both tuning and debugging the scheduler
1034	  If you aren't debugging the scheduler or trying to tune a specific
1035	  application, you can say N to avoid the very slight overhead
1036	  this adds.
1037
1038config SCHED_STACK_END_CHECK
1039	bool "Detect stack corruption on calls to schedule()"
1040	depends on DEBUG_KERNEL
1041	default n
1042	help
1043	  This option checks for a stack overrun on calls to schedule().
1044	  If the stack end location is found to be over written always panic as
1045	  the content of the corrupted region can no longer be trusted.
1046	  This is to ensure no erroneous behaviour occurs which could result in
1047	  data corruption or a sporadic crash at a later stage once the region
1048	  is examined. The runtime overhead introduced is minimal.
1049
1050config DEBUG_TIMEKEEPING
1051	bool "Enable extra timekeeping sanity checking"
1052	help
1053	  This option will enable additional timekeeping sanity checks
1054	  which may be helpful when diagnosing issues where timekeeping
1055	  problems are suspected.
1056
1057	  This may include checks in the timekeeping hotpaths, so this
1058	  option may have a (very small) performance impact to some
1059	  workloads.
1060
1061	  If unsure, say N.
1062
1063config DEBUG_PREEMPT
1064	bool "Debug preemptible kernel"
1065	depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
1066	default y
1067	help
1068	  If you say Y here then the kernel will use a debug variant of the
1069	  commonly used smp_processor_id() function and will print warnings
1070	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1071	  will detect preemption count underflows.
1072
1073menu "Lock Debugging (spinlocks, mutexes, etc...)"
1074
1075config LOCK_DEBUGGING_SUPPORT
1076	bool
1077	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1078	default y
1079
1080config PROVE_LOCKING
1081	bool "Lock debugging: prove locking correctness"
1082	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1083	select LOCKDEP
1084	select DEBUG_SPINLOCK
1085	select DEBUG_MUTEXES
1086	select DEBUG_RT_MUTEXES if RT_MUTEXES
1087	select DEBUG_RWSEMS
1088	select DEBUG_WW_MUTEX_SLOWPATH
1089	select DEBUG_LOCK_ALLOC
1090	select TRACE_IRQFLAGS
1091	default n
1092	help
1093	 This feature enables the kernel to prove that all locking
1094	 that occurs in the kernel runtime is mathematically
1095	 correct: that under no circumstance could an arbitrary (and
1096	 not yet triggered) combination of observed locking
1097	 sequences (on an arbitrary number of CPUs, running an
1098	 arbitrary number of tasks and interrupt contexts) cause a
1099	 deadlock.
1100
1101	 In short, this feature enables the kernel to report locking
1102	 related deadlocks before they actually occur.
1103
1104	 The proof does not depend on how hard and complex a
1105	 deadlock scenario would be to trigger: how many
1106	 participant CPUs, tasks and irq-contexts would be needed
1107	 for it to trigger. The proof also does not depend on
1108	 timing: if a race and a resulting deadlock is possible
1109	 theoretically (no matter how unlikely the race scenario
1110	 is), it will be proven so and will immediately be
1111	 reported by the kernel (once the event is observed that
1112	 makes the deadlock theoretically possible).
1113
1114	 If a deadlock is impossible (i.e. the locking rules, as
1115	 observed by the kernel, are mathematically correct), the
1116	 kernel reports nothing.
1117
1118	 NOTE: this feature can also be enabled for rwlocks, mutexes
1119	 and rwsems - in which case all dependencies between these
1120	 different locking variants are observed and mapped too, and
1121	 the proof of observed correctness is also maintained for an
1122	 arbitrary combination of these separate locking variants.
1123
1124	 For more details, see Documentation/locking/lockdep-design.rst.
1125
1126config LOCK_STAT
1127	bool "Lock usage statistics"
1128	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1129	select LOCKDEP
1130	select DEBUG_SPINLOCK
1131	select DEBUG_MUTEXES
1132	select DEBUG_RT_MUTEXES if RT_MUTEXES
1133	select DEBUG_LOCK_ALLOC
1134	default n
1135	help
1136	 This feature enables tracking lock contention points
1137
1138	 For more details, see Documentation/locking/lockstat.rst
1139
1140	 This also enables lock events required by "perf lock",
1141	 subcommand of perf.
1142	 If you want to use "perf lock", you also need to turn on
1143	 CONFIG_EVENT_TRACING.
1144
1145	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1146	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1147
1148config DEBUG_RT_MUTEXES
1149	bool "RT Mutex debugging, deadlock detection"
1150	depends on DEBUG_KERNEL && RT_MUTEXES
1151	help
1152	 This allows rt mutex semantics violations and rt mutex related
1153	 deadlocks (lockups) to be detected and reported automatically.
1154
1155config DEBUG_SPINLOCK
1156	bool "Spinlock and rw-lock debugging: basic checks"
1157	depends on DEBUG_KERNEL
1158	select UNINLINE_SPIN_UNLOCK
1159	help
1160	  Say Y here and build SMP to catch missing spinlock initialization
1161	  and certain other kinds of spinlock errors commonly made.  This is
1162	  best used in conjunction with the NMI watchdog so that spinlock
1163	  deadlocks are also debuggable.
1164
1165config DEBUG_MUTEXES
1166	bool "Mutex debugging: basic checks"
1167	depends on DEBUG_KERNEL
1168	help
1169	 This feature allows mutex semantics violations to be detected and
1170	 reported.
1171
1172config DEBUG_WW_MUTEX_SLOWPATH
1173	bool "Wait/wound mutex debugging: Slowpath testing"
1174	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1175	select DEBUG_LOCK_ALLOC
1176	select DEBUG_SPINLOCK
1177	select DEBUG_MUTEXES
1178	help
1179	 This feature enables slowpath testing for w/w mutex users by
1180	 injecting additional -EDEADLK wound/backoff cases. Together with
1181	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1182	 will test all possible w/w mutex interface abuse with the
1183	 exception of simply not acquiring all the required locks.
1184	 Note that this feature can introduce significant overhead, so
1185	 it really should not be enabled in a production or distro kernel,
1186	 even a debug kernel.  If you are a driver writer, enable it.  If
1187	 you are a distro, do not.
1188
1189config DEBUG_RWSEMS
1190	bool "RW Semaphore debugging: basic checks"
1191	depends on DEBUG_KERNEL
1192	help
1193	  This debugging feature allows mismatched rw semaphore locks
1194	  and unlocks to be detected and reported.
1195
1196config DEBUG_LOCK_ALLOC
1197	bool "Lock debugging: detect incorrect freeing of live locks"
1198	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1199	select DEBUG_SPINLOCK
1200	select DEBUG_MUTEXES
1201	select DEBUG_RT_MUTEXES if RT_MUTEXES
1202	select LOCKDEP
1203	help
1204	 This feature will check whether any held lock (spinlock, rwlock,
1205	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1206	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1207	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1208	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1209	 held during task exit.
1210
1211config LOCKDEP
1212	bool
1213	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1214	select STACKTRACE
1215	select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86
1216	select KALLSYMS
1217	select KALLSYMS_ALL
1218
1219config LOCKDEP_SMALL
1220	bool
1221
1222config DEBUG_LOCKDEP
1223	bool "Lock dependency engine debugging"
1224	depends on DEBUG_KERNEL && LOCKDEP
1225	help
1226	  If you say Y here, the lock dependency engine will do
1227	  additional runtime checks to debug itself, at the price
1228	  of more runtime overhead.
1229
1230config DEBUG_ATOMIC_SLEEP
1231	bool "Sleep inside atomic section checking"
1232	select PREEMPT_COUNT
1233	depends on DEBUG_KERNEL
1234	depends on !ARCH_NO_PREEMPT
1235	help
1236	  If you say Y here, various routines which may sleep will become very
1237	  noisy if they are called inside atomic sections: when a spinlock is
1238	  held, inside an rcu read side critical section, inside preempt disabled
1239	  sections, inside an interrupt, etc...
1240
1241config DEBUG_LOCKING_API_SELFTESTS
1242	bool "Locking API boot-time self-tests"
1243	depends on DEBUG_KERNEL
1244	help
1245	  Say Y here if you want the kernel to run a short self-test during
1246	  bootup. The self-test checks whether common types of locking bugs
1247	  are detected by debugging mechanisms or not. (if you disable
1248	  lock debugging then those bugs wont be detected of course.)
1249	  The following locking APIs are covered: spinlocks, rwlocks,
1250	  mutexes and rwsems.
1251
1252config LOCK_TORTURE_TEST
1253	tristate "torture tests for locking"
1254	depends on DEBUG_KERNEL
1255	select TORTURE_TEST
1256	help
1257	  This option provides a kernel module that runs torture tests
1258	  on kernel locking primitives.  The kernel module may be built
1259	  after the fact on the running kernel to be tested, if desired.
1260
1261	  Say Y here if you want kernel locking-primitive torture tests
1262	  to be built into the kernel.
1263	  Say M if you want these torture tests to build as a module.
1264	  Say N if you are unsure.
1265
1266config WW_MUTEX_SELFTEST
1267	tristate "Wait/wound mutex selftests"
1268	help
1269	  This option provides a kernel module that runs tests on the
1270	  on the struct ww_mutex locking API.
1271
1272	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1273	  with this test harness.
1274
1275	  Say M if you want these self tests to build as a module.
1276	  Say N if you are unsure.
1277
1278endmenu # lock debugging
1279
1280config TRACE_IRQFLAGS
1281	bool
1282	help
1283	  Enables hooks to interrupt enabling and disabling for
1284	  either tracing or lock debugging.
1285
1286config STACKTRACE
1287	bool "Stack backtrace support"
1288	depends on STACKTRACE_SUPPORT
1289	help
1290	  This option causes the kernel to create a /proc/pid/stack for
1291	  every process, showing its current stack trace.
1292	  It is also used by various kernel debugging features that require
1293	  stack trace generation.
1294
1295config WARN_ALL_UNSEEDED_RANDOM
1296	bool "Warn for all uses of unseeded randomness"
1297	default n
1298	help
1299	  Some parts of the kernel contain bugs relating to their use of
1300	  cryptographically secure random numbers before it's actually possible
1301	  to generate those numbers securely. This setting ensures that these
1302	  flaws don't go unnoticed, by enabling a message, should this ever
1303	  occur. This will allow people with obscure setups to know when things
1304	  are going wrong, so that they might contact developers about fixing
1305	  it.
1306
1307	  Unfortunately, on some models of some architectures getting
1308	  a fully seeded CRNG is extremely difficult, and so this can
1309	  result in dmesg getting spammed for a surprisingly long
1310	  time.  This is really bad from a security perspective, and
1311	  so architecture maintainers really need to do what they can
1312	  to get the CRNG seeded sooner after the system is booted.
1313	  However, since users cannot do anything actionable to
1314	  address this, by default the kernel will issue only a single
1315	  warning for the first use of unseeded randomness.
1316
1317	  Say Y here if you want to receive warnings for all uses of
1318	  unseeded randomness.  This will be of use primarily for
1319	  those developers interested in improving the security of
1320	  Linux kernels running on their architecture (or
1321	  subarchitecture).
1322
1323config DEBUG_KOBJECT
1324	bool "kobject debugging"
1325	depends on DEBUG_KERNEL
1326	help
1327	  If you say Y here, some extra kobject debugging messages will be sent
1328	  to the syslog.
1329
1330config DEBUG_KOBJECT_RELEASE
1331	bool "kobject release debugging"
1332	depends on DEBUG_OBJECTS_TIMERS
1333	help
1334	  kobjects are reference counted objects.  This means that their
1335	  last reference count put is not predictable, and the kobject can
1336	  live on past the point at which a driver decides to drop it's
1337	  initial reference to the kobject gained on allocation.  An
1338	  example of this would be a struct device which has just been
1339	  unregistered.
1340
1341	  However, some buggy drivers assume that after such an operation,
1342	  the memory backing the kobject can be immediately freed.  This
1343	  goes completely against the principles of a refcounted object.
1344
1345	  If you say Y here, the kernel will delay the release of kobjects
1346	  on the last reference count to improve the visibility of this
1347	  kind of kobject release bug.
1348
1349config HAVE_DEBUG_BUGVERBOSE
1350	bool
1351
1352config DEBUG_BUGVERBOSE
1353	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
1354	depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
1355	default y
1356	help
1357	  Say Y here to make BUG() panics output the file name and line number
1358	  of the BUG call as well as the EIP and oops trace.  This aids
1359	  debugging but costs about 70-100K of memory.
1360
1361config DEBUG_LIST
1362	bool "Debug linked list manipulation"
1363	depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1364	help
1365	  Enable this to turn on extended checks in the linked-list
1366	  walking routines.
1367
1368	  If unsure, say N.
1369
1370config DEBUG_PLIST
1371	bool "Debug priority linked list manipulation"
1372	depends on DEBUG_KERNEL
1373	help
1374	  Enable this to turn on extended checks in the priority-ordered
1375	  linked-list (plist) walking routines.  This checks the entire
1376	  list multiple times during each manipulation.
1377
1378	  If unsure, say N.
1379
1380config DEBUG_SG
1381	bool "Debug SG table operations"
1382	depends on DEBUG_KERNEL
1383	help
1384	  Enable this to turn on checks on scatter-gather tables. This can
1385	  help find problems with drivers that do not properly initialize
1386	  their sg tables.
1387
1388	  If unsure, say N.
1389
1390config DEBUG_NOTIFIERS
1391	bool "Debug notifier call chains"
1392	depends on DEBUG_KERNEL
1393	help
1394	  Enable this to turn on sanity checking for notifier call chains.
1395	  This is most useful for kernel developers to make sure that
1396	  modules properly unregister themselves from notifier chains.
1397	  This is a relatively cheap check but if you care about maximum
1398	  performance, say N.
1399
1400config DEBUG_CREDENTIALS
1401	bool "Debug credential management"
1402	depends on DEBUG_KERNEL
1403	help
1404	  Enable this to turn on some debug checking for credential
1405	  management.  The additional code keeps track of the number of
1406	  pointers from task_structs to any given cred struct, and checks to
1407	  see that this number never exceeds the usage count of the cred
1408	  struct.
1409
1410	  Furthermore, if SELinux is enabled, this also checks that the
1411	  security pointer in the cred struct is never seen to be invalid.
1412
1413	  If unsure, say N.
1414
1415source "kernel/rcu/Kconfig.debug"
1416
1417config DEBUG_WQ_FORCE_RR_CPU
1418	bool "Force round-robin CPU selection for unbound work items"
1419	depends on DEBUG_KERNEL
1420	default n
1421	help
1422	  Workqueue used to implicitly guarantee that work items queued
1423	  without explicit CPU specified are put on the local CPU.  This
1424	  guarantee is no longer true and while local CPU is still
1425	  preferred work items may be put on foreign CPUs.  Kernel
1426	  parameter "workqueue.debug_force_rr_cpu" is added to force
1427	  round-robin CPU selection to flush out usages which depend on the
1428	  now broken guarantee.  This config option enables the debug
1429	  feature by default.  When enabled, memory and cache locality will
1430	  be impacted.
1431
1432config DEBUG_BLOCK_EXT_DEVT
1433        bool "Force extended block device numbers and spread them"
1434	depends on DEBUG_KERNEL
1435	depends on BLOCK
1436	default n
1437	help
1438	  BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1439	  SOME DISTRIBUTIONS.  DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1440	  YOU ARE DOING.  Distros, please enable this and fix whatever
1441	  is broken.
1442
1443	  Conventionally, block device numbers are allocated from
1444	  predetermined contiguous area.  However, extended block area
1445	  may introduce non-contiguous block device numbers.  This
1446	  option forces most block device numbers to be allocated from
1447	  the extended space and spreads them to discover kernel or
1448	  userland code paths which assume predetermined contiguous
1449	  device number allocation.
1450
1451	  Note that turning on this debug option shuffles all the
1452	  device numbers for all IDE and SCSI devices including libata
1453	  ones, so root partition specified using device number
1454	  directly (via rdev or root=MAJ:MIN) won't work anymore.
1455	  Textual device names (root=/dev/sdXn) will continue to work.
1456
1457	  Say N if you are unsure.
1458
1459config CPU_HOTPLUG_STATE_CONTROL
1460	bool "Enable CPU hotplug state control"
1461	depends on DEBUG_KERNEL
1462	depends on HOTPLUG_CPU
1463	default n
1464	help
1465	  Allows to write steps between "offline" and "online" to the CPUs
1466	  sysfs target file so states can be stepped granular. This is a debug
1467	  option for now as the hotplug machinery cannot be stopped and
1468	  restarted at arbitrary points yet.
1469
1470	  Say N if your are unsure.
1471
1472config NOTIFIER_ERROR_INJECTION
1473	tristate "Notifier error injection"
1474	depends on DEBUG_KERNEL
1475	select DEBUG_FS
1476	help
1477	  This option provides the ability to inject artificial errors to
1478	  specified notifier chain callbacks. It is useful to test the error
1479	  handling of notifier call chain failures.
1480
1481	  Say N if unsure.
1482
1483config PM_NOTIFIER_ERROR_INJECT
1484	tristate "PM notifier error injection module"
1485	depends on PM && NOTIFIER_ERROR_INJECTION
1486	default m if PM_DEBUG
1487	help
1488	  This option provides the ability to inject artificial errors to
1489	  PM notifier chain callbacks.  It is controlled through debugfs
1490	  interface /sys/kernel/debug/notifier-error-inject/pm
1491
1492	  If the notifier call chain should be failed with some events
1493	  notified, write the error code to "actions/<notifier event>/error".
1494
1495	  Example: Inject PM suspend error (-12 = -ENOMEM)
1496
1497	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1498	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1499	  # echo mem > /sys/power/state
1500	  bash: echo: write error: Cannot allocate memory
1501
1502	  To compile this code as a module, choose M here: the module will
1503	  be called pm-notifier-error-inject.
1504
1505	  If unsure, say N.
1506
1507config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1508	tristate "OF reconfig notifier error injection module"
1509	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1510	help
1511	  This option provides the ability to inject artificial errors to
1512	  OF reconfig notifier chain callbacks.  It is controlled
1513	  through debugfs interface under
1514	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1515
1516	  If the notifier call chain should be failed with some events
1517	  notified, write the error code to "actions/<notifier event>/error".
1518
1519	  To compile this code as a module, choose M here: the module will
1520	  be called of-reconfig-notifier-error-inject.
1521
1522	  If unsure, say N.
1523
1524config NETDEV_NOTIFIER_ERROR_INJECT
1525	tristate "Netdev notifier error injection module"
1526	depends on NET && NOTIFIER_ERROR_INJECTION
1527	help
1528	  This option provides the ability to inject artificial errors to
1529	  netdevice notifier chain callbacks.  It is controlled through debugfs
1530	  interface /sys/kernel/debug/notifier-error-inject/netdev
1531
1532	  If the notifier call chain should be failed with some events
1533	  notified, write the error code to "actions/<notifier event>/error".
1534
1535	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1536
1537	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1538	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1539	  # ip link set eth0 mtu 1024
1540	  RTNETLINK answers: Invalid argument
1541
1542	  To compile this code as a module, choose M here: the module will
1543	  be called netdev-notifier-error-inject.
1544
1545	  If unsure, say N.
1546
1547config FUNCTION_ERROR_INJECTION
1548	def_bool y
1549	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1550
1551config FAULT_INJECTION
1552	bool "Fault-injection framework"
1553	depends on DEBUG_KERNEL
1554	help
1555	  Provide fault-injection framework.
1556	  For more details, see Documentation/fault-injection/.
1557
1558config FAILSLAB
1559	bool "Fault-injection capability for kmalloc"
1560	depends on FAULT_INJECTION
1561	depends on SLAB || SLUB
1562	help
1563	  Provide fault-injection capability for kmalloc.
1564
1565config FAIL_PAGE_ALLOC
1566	bool "Fault-injection capabilitiy for alloc_pages()"
1567	depends on FAULT_INJECTION
1568	help
1569	  Provide fault-injection capability for alloc_pages().
1570
1571config FAIL_MAKE_REQUEST
1572	bool "Fault-injection capability for disk IO"
1573	depends on FAULT_INJECTION && BLOCK
1574	help
1575	  Provide fault-injection capability for disk IO.
1576
1577config FAIL_IO_TIMEOUT
1578	bool "Fault-injection capability for faking disk interrupts"
1579	depends on FAULT_INJECTION && BLOCK
1580	help
1581	  Provide fault-injection capability on end IO handling. This
1582	  will make the block layer "forget" an interrupt as configured,
1583	  thus exercising the error handling.
1584
1585	  Only works with drivers that use the generic timeout handling,
1586	  for others it wont do anything.
1587
1588config FAIL_FUTEX
1589	bool "Fault-injection capability for futexes"
1590	select DEBUG_FS
1591	depends on FAULT_INJECTION && FUTEX
1592	help
1593	  Provide fault-injection capability for futexes.
1594
1595config FAULT_INJECTION_DEBUG_FS
1596	bool "Debugfs entries for fault-injection capabilities"
1597	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1598	help
1599	  Enable configuration of fault-injection capabilities via debugfs.
1600
1601config FAIL_FUNCTION
1602	bool "Fault-injection capability for functions"
1603	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1604	help
1605	  Provide function-based fault-injection capability.
1606	  This will allow you to override a specific function with a return
1607	  with given return value. As a result, function caller will see
1608	  an error value and have to handle it. This is useful to test the
1609	  error handling in various subsystems.
1610
1611config FAIL_MMC_REQUEST
1612	bool "Fault-injection capability for MMC IO"
1613	depends on FAULT_INJECTION_DEBUG_FS && MMC
1614	help
1615	  Provide fault-injection capability for MMC IO.
1616	  This will make the mmc core return data errors. This is
1617	  useful to test the error handling in the mmc block device
1618	  and to test how the mmc host driver handles retries from
1619	  the block device.
1620
1621config FAULT_INJECTION_STACKTRACE_FILTER
1622	bool "stacktrace filter for fault-injection capabilities"
1623	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1624	depends on !X86_64
1625	select STACKTRACE
1626	select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1627	help
1628	  Provide stacktrace filter for fault-injection capabilities
1629
1630config LATENCYTOP
1631	bool "Latency measuring infrastructure"
1632	depends on DEBUG_KERNEL
1633	depends on STACKTRACE_SUPPORT
1634	depends on PROC_FS
1635	select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM && !ARC && !X86
1636	select KALLSYMS
1637	select KALLSYMS_ALL
1638	select STACKTRACE
1639	select SCHEDSTATS
1640	select SCHED_DEBUG
1641	help
1642	  Enable this option if you want to use the LatencyTOP tool
1643	  to find out which userspace is blocking on what kernel operations.
1644
1645source "kernel/trace/Kconfig"
1646
1647config PROVIDE_OHCI1394_DMA_INIT
1648	bool "Remote debugging over FireWire early on boot"
1649	depends on PCI && X86
1650	help
1651	  If you want to debug problems which hang or crash the kernel early
1652	  on boot and the crashing machine has a FireWire port, you can use
1653	  this feature to remotely access the memory of the crashed machine
1654	  over FireWire. This employs remote DMA as part of the OHCI1394
1655	  specification which is now the standard for FireWire controllers.
1656
1657	  With remote DMA, you can monitor the printk buffer remotely using
1658	  firescope and access all memory below 4GB using fireproxy from gdb.
1659	  Even controlling a kernel debugger is possible using remote DMA.
1660
1661	  Usage:
1662
1663	  If ohci1394_dma=early is used as boot parameter, it will initialize
1664	  all OHCI1394 controllers which are found in the PCI config space.
1665
1666	  As all changes to the FireWire bus such as enabling and disabling
1667	  devices cause a bus reset and thereby disable remote DMA for all
1668	  devices, be sure to have the cable plugged and FireWire enabled on
1669	  the debugging host before booting the debug target for debugging.
1670
1671	  This code (~1k) is freed after boot. By then, the firewire stack
1672	  in charge of the OHCI-1394 controllers should be used instead.
1673
1674	  See Documentation/debugging-via-ohci1394.txt for more information.
1675
1676source "lib/kunit/Kconfig"
1677
1678menuconfig RUNTIME_TESTING_MENU
1679	bool "Runtime Testing"
1680	def_bool y
1681
1682if RUNTIME_TESTING_MENU
1683
1684config LKDTM
1685	tristate "Linux Kernel Dump Test Tool Module"
1686	depends on DEBUG_FS
1687	help
1688	This module enables testing of the different dumping mechanisms by
1689	inducing system failures at predefined crash points.
1690	If you don't need it: say N
1691	Choose M here to compile this code as a module. The module will be
1692	called lkdtm.
1693
1694	Documentation on how to use the module can be found in
1695	Documentation/fault-injection/provoke-crashes.rst
1696
1697config TEST_LIST_SORT
1698	tristate "Linked list sorting test"
1699	depends on DEBUG_KERNEL || m
1700	help
1701	  Enable this to turn on 'list_sort()' function test. This test is
1702	  executed only once during system boot (so affects only boot time),
1703	  or at module load time.
1704
1705	  If unsure, say N.
1706
1707config TEST_SORT
1708	tristate "Array-based sort test"
1709	depends on DEBUG_KERNEL || m
1710	help
1711	  This option enables the self-test function of 'sort()' at boot,
1712	  or at module load time.
1713
1714	  If unsure, say N.
1715
1716config KPROBES_SANITY_TEST
1717	bool "Kprobes sanity tests"
1718	depends on DEBUG_KERNEL
1719	depends on KPROBES
1720	help
1721	  This option provides for testing basic kprobes functionality on
1722	  boot. Samples of kprobe and kretprobe are inserted and
1723	  verified for functionality.
1724
1725	  Say N if you are unsure.
1726
1727config BACKTRACE_SELF_TEST
1728	tristate "Self test for the backtrace code"
1729	depends on DEBUG_KERNEL
1730	help
1731	  This option provides a kernel module that can be used to test
1732	  the kernel stack backtrace code. This option is not useful
1733	  for distributions or general kernels, but only for kernel
1734	  developers working on architecture code.
1735
1736	  Note that if you want to also test saved backtraces, you will
1737	  have to enable STACKTRACE as well.
1738
1739	  Say N if you are unsure.
1740
1741config RBTREE_TEST
1742	tristate "Red-Black tree test"
1743	depends on DEBUG_KERNEL
1744	help
1745	  A benchmark measuring the performance of the rbtree library.
1746	  Also includes rbtree invariant checks.
1747
1748config REED_SOLOMON_TEST
1749	tristate "Reed-Solomon library test"
1750	depends on DEBUG_KERNEL || m
1751	select REED_SOLOMON
1752	select REED_SOLOMON_ENC16
1753	select REED_SOLOMON_DEC16
1754	help
1755	  This option enables the self-test function of rslib at boot,
1756	  or at module load time.
1757
1758	  If unsure, say N.
1759
1760config INTERVAL_TREE_TEST
1761	tristate "Interval tree test"
1762	depends on DEBUG_KERNEL
1763	select INTERVAL_TREE
1764	help
1765	  A benchmark measuring the performance of the interval tree library
1766
1767config PERCPU_TEST
1768	tristate "Per cpu operations test"
1769	depends on m && DEBUG_KERNEL
1770	help
1771	  Enable this option to build test module which validates per-cpu
1772	  operations.
1773
1774	  If unsure, say N.
1775
1776config ATOMIC64_SELFTEST
1777	tristate "Perform an atomic64_t self-test"
1778	help
1779	  Enable this option to test the atomic64_t functions at boot or
1780	  at module load time.
1781
1782	  If unsure, say N.
1783
1784config ASYNC_RAID6_TEST
1785	tristate "Self test for hardware accelerated raid6 recovery"
1786	depends on ASYNC_RAID6_RECOV
1787	select ASYNC_MEMCPY
1788	---help---
1789	  This is a one-shot self test that permutes through the
1790	  recovery of all the possible two disk failure scenarios for a
1791	  N-disk array.  Recovery is performed with the asynchronous
1792	  raid6 recovery routines, and will optionally use an offload
1793	  engine if one is available.
1794
1795	  If unsure, say N.
1796
1797config TEST_HEXDUMP
1798	tristate "Test functions located in the hexdump module at runtime"
1799
1800config TEST_STRING_HELPERS
1801	tristate "Test functions located in the string_helpers module at runtime"
1802
1803config TEST_STRSCPY
1804	tristate "Test strscpy*() family of functions at runtime"
1805
1806config TEST_KSTRTOX
1807	tristate "Test kstrto*() family of functions at runtime"
1808
1809config TEST_PRINTF
1810	tristate "Test printf() family of functions at runtime"
1811
1812config TEST_BITMAP
1813	tristate "Test bitmap_*() family of functions at runtime"
1814	help
1815	  Enable this option to test the bitmap functions at boot.
1816
1817	  If unsure, say N.
1818
1819config TEST_BITFIELD
1820	tristate "Test bitfield functions at runtime"
1821	help
1822	  Enable this option to test the bitfield functions at boot.
1823
1824	  If unsure, say N.
1825
1826config TEST_UUID
1827	tristate "Test functions located in the uuid module at runtime"
1828
1829config TEST_XARRAY
1830	tristate "Test the XArray code at runtime"
1831
1832config TEST_OVERFLOW
1833	tristate "Test check_*_overflow() functions at runtime"
1834
1835config TEST_RHASHTABLE
1836	tristate "Perform selftest on resizable hash table"
1837	help
1838	  Enable this option to test the rhashtable functions at boot.
1839
1840	  If unsure, say N.
1841
1842config TEST_HASH
1843	tristate "Perform selftest on hash functions"
1844	help
1845	  Enable this option to test the kernel's integer (<linux/hash.h>),
1846	  string (<linux/stringhash.h>), and siphash (<linux/siphash.h>)
1847	  hash functions on boot (or module load).
1848
1849	  This is intended to help people writing architecture-specific
1850	  optimized versions.  If unsure, say N.
1851
1852config TEST_IDA
1853	tristate "Perform selftest on IDA functions"
1854
1855config TEST_PARMAN
1856	tristate "Perform selftest on priority array manager"
1857	depends on PARMAN
1858	help
1859	  Enable this option to test priority array manager on boot
1860	  (or module load).
1861
1862	  If unsure, say N.
1863
1864config TEST_IRQ_TIMINGS
1865	bool "IRQ timings selftest"
1866	depends on IRQ_TIMINGS
1867	help
1868	  Enable this option to test the irq timings code on boot.
1869
1870	  If unsure, say N.
1871
1872config TEST_LKM
1873	tristate "Test module loading with 'hello world' module"
1874	depends on m
1875	help
1876	  This builds the "test_module" module that emits "Hello, world"
1877	  on printk when loaded. It is designed to be used for basic
1878	  evaluation of the module loading subsystem (for example when
1879	  validating module verification). It lacks any extra dependencies,
1880	  and will not normally be loaded by the system unless explicitly
1881	  requested by name.
1882
1883	  If unsure, say N.
1884
1885config TEST_VMALLOC
1886	tristate "Test module for stress/performance analysis of vmalloc allocator"
1887	default n
1888       depends on MMU
1889	depends on m
1890	help
1891	  This builds the "test_vmalloc" module that should be used for
1892	  stress and performance analysis. So, any new change for vmalloc
1893	  subsystem can be evaluated from performance and stability point
1894	  of view.
1895
1896	  If unsure, say N.
1897
1898config TEST_USER_COPY
1899	tristate "Test user/kernel boundary protections"
1900	depends on m
1901	help
1902	  This builds the "test_user_copy" module that runs sanity checks
1903	  on the copy_to/from_user infrastructure, making sure basic
1904	  user/kernel boundary testing is working. If it fails to load,
1905	  a regression has been detected in the user/kernel memory boundary
1906	  protections.
1907
1908	  If unsure, say N.
1909
1910config TEST_BPF
1911	tristate "Test BPF filter functionality"
1912	depends on m && NET
1913	help
1914	  This builds the "test_bpf" module that runs various test vectors
1915	  against the BPF interpreter or BPF JIT compiler depending on the
1916	  current setting. This is in particular useful for BPF JIT compiler
1917	  development, but also to run regression tests against changes in
1918	  the interpreter code. It also enables test stubs for eBPF maps and
1919	  verifier used by user space verifier testsuite.
1920
1921	  If unsure, say N.
1922
1923config TEST_BLACKHOLE_DEV
1924	tristate "Test blackhole netdev functionality"
1925	depends on m && NET
1926	help
1927	  This builds the "test_blackhole_dev" module that validates the
1928	  data path through this blackhole netdev.
1929
1930	  If unsure, say N.
1931
1932config FIND_BIT_BENCHMARK
1933	tristate "Test find_bit functions"
1934	help
1935	  This builds the "test_find_bit" module that measure find_*_bit()
1936	  functions performance.
1937
1938	  If unsure, say N.
1939
1940config TEST_FIRMWARE
1941	tristate "Test firmware loading via userspace interface"
1942	depends on FW_LOADER
1943	help
1944	  This builds the "test_firmware" module that creates a userspace
1945	  interface for testing firmware loading. This can be used to
1946	  control the triggering of firmware loading without needing an
1947	  actual firmware-using device. The contents can be rechecked by
1948	  userspace.
1949
1950	  If unsure, say N.
1951
1952config TEST_SYSCTL
1953	tristate "sysctl test driver"
1954	depends on PROC_SYSCTL
1955	help
1956	  This builds the "test_sysctl" module. This driver enables to test the
1957	  proc sysctl interfaces available to drivers safely without affecting
1958	  production knobs which might alter system functionality.
1959
1960	  If unsure, say N.
1961
1962config SYSCTL_KUNIT_TEST
1963	bool "KUnit test for sysctl"
1964	depends on KUNIT
1965	help
1966	  This builds the proc sysctl unit test, which runs on boot.
1967	  Tests the API contract and implementation correctness of sysctl.
1968	  For more information on KUnit and unit tests in general please refer
1969	  to the KUnit documentation in Documentation/dev-tools/kunit/.
1970
1971	  If unsure, say N.
1972
1973config LIST_KUNIT_TEST
1974	bool "KUnit Test for Kernel Linked-list structures"
1975	depends on KUNIT
1976	help
1977	  This builds the linked list KUnit test suite.
1978	  It tests that the API and basic functionality of the list_head type
1979	  and associated macros.
1980
1981	  KUnit tests run during boot and output the results to the debug log
1982	  in TAP format (http://testanything.org/). Only useful for kernel devs
1983	  running the KUnit test harness, and not intended for inclusion into a
1984	  production build.
1985
1986	  For more information on KUnit and unit tests in general please refer
1987	  to the KUnit documentation in Documentation/dev-tools/kunit/.
1988
1989	  If unsure, say N.
1990
1991config TEST_UDELAY
1992	tristate "udelay test driver"
1993	help
1994	  This builds the "udelay_test" module that helps to make sure
1995	  that udelay() is working properly.
1996
1997	  If unsure, say N.
1998
1999config TEST_STATIC_KEYS
2000	tristate "Test static keys"
2001	depends on m
2002	help
2003	  Test the static key interfaces.
2004
2005	  If unsure, say N.
2006
2007config TEST_KMOD
2008	tristate "kmod stress tester"
2009	depends on m
2010	depends on NETDEVICES && NET_CORE && INET # for TUN
2011	depends on BLOCK
2012	select TEST_LKM
2013	select XFS_FS
2014	select TUN
2015	select BTRFS_FS
2016	help
2017	  Test the kernel's module loading mechanism: kmod. kmod implements
2018	  support to load modules using the Linux kernel's usermode helper.
2019	  This test provides a series of tests against kmod.
2020
2021	  Although technically you can either build test_kmod as a module or
2022	  into the kernel we disallow building it into the kernel since
2023	  it stress tests request_module() and this will very likely cause
2024	  some issues by taking over precious threads available from other
2025	  module load requests, ultimately this could be fatal.
2026
2027	  To run tests run:
2028
2029	  tools/testing/selftests/kmod/kmod.sh --help
2030
2031	  If unsure, say N.
2032
2033config TEST_DEBUG_VIRTUAL
2034	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2035	depends on DEBUG_VIRTUAL
2036	help
2037	  Test the kernel's ability to detect incorrect calls to
2038	  virt_to_phys() done against the non-linear part of the
2039	  kernel's virtual address map.
2040
2041	  If unsure, say N.
2042
2043config TEST_MEMCAT_P
2044	tristate "Test memcat_p() helper function"
2045	help
2046	  Test the memcat_p() helper for correctly merging two
2047	  pointer arrays together.
2048
2049	  If unsure, say N.
2050
2051config TEST_LIVEPATCH
2052	tristate "Test livepatching"
2053	default n
2054	depends on DYNAMIC_DEBUG
2055	depends on LIVEPATCH
2056	depends on m
2057	help
2058	  Test kernel livepatching features for correctness.  The tests will
2059	  load test modules that will be livepatched in various scenarios.
2060
2061	  To run all the livepatching tests:
2062
2063	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2064
2065	  Alternatively, individual tests may be invoked:
2066
2067	  tools/testing/selftests/livepatch/test-callbacks.sh
2068	  tools/testing/selftests/livepatch/test-livepatch.sh
2069	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2070
2071	  If unsure, say N.
2072
2073config TEST_OBJAGG
2074	tristate "Perform selftest on object aggreration manager"
2075	default n
2076	depends on OBJAGG
2077	help
2078	  Enable this option to test object aggregation manager on boot
2079	  (or module load).
2080
2081
2082config TEST_STACKINIT
2083	tristate "Test level of stack variable initialization"
2084	help
2085	  Test if the kernel is zero-initializing stack variables and
2086	  padding. Coverage is controlled by compiler flags,
2087	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2088	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2089
2090	  If unsure, say N.
2091
2092config TEST_MEMINIT
2093	tristate "Test heap/page initialization"
2094	help
2095	  Test if the kernel is zero-initializing heap and page allocations.
2096	  This can be useful to test init_on_alloc and init_on_free features.
2097
2098	  If unsure, say N.
2099
2100endif # RUNTIME_TESTING_MENU
2101
2102config MEMTEST
2103	bool "Memtest"
2104	---help---
2105	  This option adds a kernel parameter 'memtest', which allows memtest
2106	  to be set.
2107	        memtest=0, mean disabled; -- default
2108	        memtest=1, mean do 1 test pattern;
2109	        ...
2110	        memtest=17, mean do 17 test patterns.
2111	  If you are unsure how to answer this question, answer N.
2112
2113config BUG_ON_DATA_CORRUPTION
2114	bool "Trigger a BUG when data corruption is detected"
2115	select DEBUG_LIST
2116	help
2117	  Select this option if the kernel should BUG when it encounters
2118	  data corruption in kernel memory structures when they get checked
2119	  for validity.
2120
2121	  If unsure, say N.
2122
2123source "samples/Kconfig"
2124
2125source "lib/Kconfig.kgdb"
2126
2127source "lib/Kconfig.ubsan"
2128
2129config ARCH_HAS_DEVMEM_IS_ALLOWED
2130	bool
2131
2132config STRICT_DEVMEM
2133	bool "Filter access to /dev/mem"
2134	depends on MMU && DEVMEM
2135	depends on ARCH_HAS_DEVMEM_IS_ALLOWED
2136	default y if PPC || X86 || ARM64
2137	---help---
2138	  If this option is disabled, you allow userspace (root) access to all
2139	  of memory, including kernel and userspace memory. Accidental
2140	  access to this is obviously disastrous, but specific access can
2141	  be used by people debugging the kernel. Note that with PAT support
2142	  enabled, even in this case there are restrictions on /dev/mem
2143	  use due to the cache aliasing requirements.
2144
2145	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
2146	  file only allows userspace access to PCI space and the BIOS code and
2147	  data regions.  This is sufficient for dosemu and X and all common
2148	  users of /dev/mem.
2149
2150	  If in doubt, say Y.
2151
2152config IO_STRICT_DEVMEM
2153	bool "Filter I/O access to /dev/mem"
2154	depends on STRICT_DEVMEM
2155	---help---
2156	  If this option is disabled, you allow userspace (root) access to all
2157	  io-memory regardless of whether a driver is actively using that
2158	  range.  Accidental access to this is obviously disastrous, but
2159	  specific access can be used by people debugging kernel drivers.
2160
2161	  If this option is switched on, the /dev/mem file only allows
2162	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
2163	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
2164	  if the driver using a given range cannot be disabled.
2165
2166	  If in doubt, say Y.
2167
2168source "arch/$(SRCARCH)/Kconfig.debug"
2169
2170endmenu # Kernel hacking
2171