xref: /openbmc/linux/lib/Kconfig.debug (revision 9322af3e6aeae04c7eda3e6a0c977e97a13cf6ed)
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 STACKTRACE_BUILD_ID
39	bool "Show build ID information in stacktraces"
40	depends on PRINTK
41	help
42	  Selecting this option adds build ID information for symbols in
43	  stacktraces printed with the printk format '%p[SR]b'.
44
45	  This option is intended for distros where debuginfo is not easily
46	  accessible but can be downloaded given the build ID of the vmlinux or
47	  kernel module where the function is located.
48
49config CONSOLE_LOGLEVEL_DEFAULT
50	int "Default console loglevel (1-15)"
51	range 1 15
52	default "7"
53	help
54	  Default loglevel to determine what will be printed on the console.
55
56	  Setting a default here is equivalent to passing in loglevel=<x> in
57	  the kernel bootargs. loglevel=<x> continues to override whatever
58	  value is specified here as well.
59
60	  Note: This does not affect the log level of un-prefixed printk()
61	  usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
62	  option.
63
64config CONSOLE_LOGLEVEL_QUIET
65	int "quiet console loglevel (1-15)"
66	range 1 15
67	default "4"
68	help
69	  loglevel to use when "quiet" is passed on the kernel commandline.
70
71	  When "quiet" is passed on the kernel commandline this loglevel
72	  will be used as the loglevel. IOW passing "quiet" will be the
73	  equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
74
75config MESSAGE_LOGLEVEL_DEFAULT
76	int "Default message log level (1-7)"
77	range 1 7
78	default "4"
79	help
80	  Default log level for printk statements with no specified priority.
81
82	  This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
83	  that are auditing their logs closely may want to set it to a lower
84	  priority.
85
86	  Note: This does not affect what message level gets printed on the console
87	  by default. To change that, use loglevel=<x> in the kernel bootargs,
88	  or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
89
90config BOOT_PRINTK_DELAY
91	bool "Delay each boot printk message by N milliseconds"
92	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
93	help
94	  This build option allows you to read kernel boot messages
95	  by inserting a short delay after each one.  The delay is
96	  specified in milliseconds on the kernel command line,
97	  using "boot_delay=N".
98
99	  It is likely that you would also need to use "lpj=M" to preset
100	  the "loops per jiffie" value.
101	  See a previous boot log for the "lpj" value to use for your
102	  system, and then set "lpj=M" before setting "boot_delay=N".
103	  NOTE:  Using this option may adversely affect SMP systems.
104	  I.e., processors other than the first one may not boot up.
105	  BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
106	  what it believes to be lockup conditions.
107
108config DYNAMIC_DEBUG
109	bool "Enable dynamic printk() support"
110	default n
111	depends on PRINTK
112	depends on (DEBUG_FS || PROC_FS)
113	select DYNAMIC_DEBUG_CORE
114	help
115
116	  Compiles debug level messages into the kernel, which would not
117	  otherwise be available at runtime. These messages can then be
118	  enabled/disabled based on various levels of scope - per source file,
119	  function, module, format string, and line number. This mechanism
120	  implicitly compiles in all pr_debug() and dev_dbg() calls, which
121	  enlarges the kernel text size by about 2%.
122
123	  If a source file is compiled with DEBUG flag set, any
124	  pr_debug() calls in it are enabled by default, but can be
125	  disabled at runtime as below.  Note that DEBUG flag is
126	  turned on by many CONFIG_*DEBUG* options.
127
128	  Usage:
129
130	  Dynamic debugging is controlled via the 'dynamic_debug/control' file,
131	  which is contained in the 'debugfs' filesystem or procfs.
132	  Thus, the debugfs or procfs filesystem must first be mounted before
133	  making use of this feature.
134	  We refer the control file as: <debugfs>/dynamic_debug/control. This
135	  file contains a list of the debug statements that can be enabled. The
136	  format for each line of the file is:
137
138		filename:lineno [module]function flags format
139
140	  filename : source file of the debug statement
141	  lineno : line number of the debug statement
142	  module : module that contains the debug statement
143	  function : function that contains the debug statement
144	  flags : '=p' means the line is turned 'on' for printing
145	  format : the format used for the debug statement
146
147	  From a live system:
148
149		nullarbor:~ # cat <debugfs>/dynamic_debug/control
150		# filename:lineno [module]function flags format
151		fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
152		fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
153		fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
154
155	  Example usage:
156
157		// enable the message at line 1603 of file svcsock.c
158		nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
159						<debugfs>/dynamic_debug/control
160
161		// enable all the messages in file svcsock.c
162		nullarbor:~ # echo -n 'file svcsock.c +p' >
163						<debugfs>/dynamic_debug/control
164
165		// enable all the messages in the NFS server module
166		nullarbor:~ # echo -n 'module nfsd +p' >
167						<debugfs>/dynamic_debug/control
168
169		// enable all 12 messages in the function svc_process()
170		nullarbor:~ # echo -n 'func svc_process +p' >
171						<debugfs>/dynamic_debug/control
172
173		// disable all 12 messages in the function svc_process()
174		nullarbor:~ # echo -n 'func svc_process -p' >
175						<debugfs>/dynamic_debug/control
176
177	  See Documentation/admin-guide/dynamic-debug-howto.rst for additional
178	  information.
179
180config DYNAMIC_DEBUG_CORE
181	bool "Enable core function of dynamic debug support"
182	depends on PRINTK
183	depends on (DEBUG_FS || PROC_FS)
184	help
185	  Enable core functional support of dynamic debug. It is useful
186	  when you want to tie dynamic debug to your kernel modules with
187	  DYNAMIC_DEBUG_MODULE defined for each of them, especially for
188	  the case of embedded system where the kernel image size is
189	  sensitive for people.
190
191config SYMBOLIC_ERRNAME
192	bool "Support symbolic error names in printf"
193	default y if PRINTK
194	help
195	  If you say Y here, the kernel's printf implementation will
196	  be able to print symbolic error names such as ENOSPC instead
197	  of the number 28. It makes the kernel image slightly larger
198	  (about 3KB), but can make the kernel logs easier to read.
199
200config DEBUG_BUGVERBOSE
201	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
202	depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
203	default y
204	help
205	  Say Y here to make BUG() panics output the file name and line number
206	  of the BUG call as well as the EIP and oops trace.  This aids
207	  debugging but costs about 70-100K of memory.
208
209endmenu # "printk and dmesg options"
210
211config DEBUG_KERNEL
212	bool "Kernel debugging"
213	help
214	  Say Y here if you are developing drivers or trying to debug and
215	  identify kernel problems.
216
217config DEBUG_MISC
218	bool "Miscellaneous debug code"
219	default DEBUG_KERNEL
220	depends on DEBUG_KERNEL
221	help
222	  Say Y here if you need to enable miscellaneous debug code that should
223	  be under a more specific debug option but isn't.
224
225menu "Compile-time checks and compiler options"
226
227config DEBUG_INFO
228	bool
229	help
230	  A kernel debug info option other than "None" has been selected
231	  in the "Debug information" choice below, indicating that debug
232	  information will be generated for build targets.
233
234# Clang is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which
235# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
236config AS_HAS_NON_CONST_LEB128
237	def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
238
239choice
240	prompt "Debug information"
241	depends on DEBUG_KERNEL
242	help
243	  Selecting something other than "None" results in a kernel image
244	  that will include debugging info resulting in a larger kernel image.
245	  This adds debug symbols to the kernel and modules (gcc -g), and
246	  is needed if you intend to use kernel crashdump or binary object
247	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
248
249	  Choose which version of DWARF debug info to emit. If unsure,
250	  select "Toolchain default".
251
252config DEBUG_INFO_NONE
253	bool "Disable debug information"
254	help
255	  Do not build the kernel with debugging information, which will
256	  result in a faster and smaller build.
257
258config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
259	bool "Rely on the toolchain's implicit default DWARF version"
260	select DEBUG_INFO
261	depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
262	help
263	  The implicit default version of DWARF debug info produced by a
264	  toolchain changes over time.
265
266	  This can break consumers of the debug info that haven't upgraded to
267	  support newer revisions, and prevent testing newer versions, but
268	  those should be less common scenarios.
269
270config DEBUG_INFO_DWARF4
271	bool "Generate DWARF Version 4 debuginfo"
272	select DEBUG_INFO
273	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
274	help
275	  Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
276	  if using clang without clang's integrated assembler, and gdb 7.0+.
277
278	  If you have consumers of DWARF debug info that are not ready for
279	  newer revisions of DWARF, you may wish to choose this or have your
280	  config select this.
281
282config DEBUG_INFO_DWARF5
283	bool "Generate DWARF Version 5 debuginfo"
284	select DEBUG_INFO
285	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
286	help
287	  Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
288	  5.0+ accepts the -gdwarf-5 flag but only had partial support for some
289	  draft features until 7.0), and gdb 8.0+.
290
291	  Changes to the structure of debug info in Version 5 allow for around
292	  15-18% savings in resulting image and debug info section sizes as
293	  compared to DWARF Version 4. DWARF Version 5 standardizes previous
294	  extensions such as accelerators for symbol indexing and the format
295	  for fission (.dwo/.dwp) files. Users may not want to select this
296	  config if they rely on tooling that has not yet been updated to
297	  support DWARF Version 5.
298
299endchoice # "Debug information"
300
301if DEBUG_INFO
302
303config DEBUG_INFO_REDUCED
304	bool "Reduce debugging information"
305	help
306	  If you say Y here gcc is instructed to generate less debugging
307	  information for structure types. This means that tools that
308	  need full debugging information (like kgdb or systemtap) won't
309	  be happy. But if you merely need debugging information to
310	  resolve line numbers there is no loss. Advantage is that
311	  build directory object sizes shrink dramatically over a full
312	  DEBUG_INFO build and compile times are reduced too.
313	  Only works with newer gcc versions.
314
315config DEBUG_INFO_COMPRESSED
316	bool "Compressed debugging information"
317	depends on $(cc-option,-gz=zlib)
318	depends on $(ld-option,--compress-debug-sections=zlib)
319	help
320	  Compress the debug information using zlib.  Requires GCC 5.0+ or Clang
321	  5.0+, binutils 2.26+, and zlib.
322
323	  Users of dpkg-deb via scripts/package/builddeb may find an increase in
324	  size of their debug .deb packages with this config set, due to the
325	  debug info being compressed with zlib, then the object files being
326	  recompressed with a different compression scheme. But this is still
327	  preferable to setting $KDEB_COMPRESS to "none" which would be even
328	  larger.
329
330config DEBUG_INFO_SPLIT
331	bool "Produce split debuginfo in .dwo files"
332	depends on $(cc-option,-gsplit-dwarf)
333	help
334	  Generate debug info into separate .dwo files. This significantly
335	  reduces the build directory size for builds with DEBUG_INFO,
336	  because it stores the information only once on disk in .dwo
337	  files instead of multiple times in object files and executables.
338	  In addition the debug information is also compressed.
339
340	  Requires recent gcc (4.7+) and recent gdb/binutils.
341	  Any tool that packages or reads debug information would need
342	  to know about the .dwo files and include them.
343	  Incompatible with older versions of ccache.
344
345config DEBUG_INFO_BTF
346	bool "Generate BTF typeinfo"
347	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
348	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
349	depends on BPF_SYSCALL
350	depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
351	help
352	  Generate deduplicated BTF type information from DWARF debug info.
353	  Turning this on expects presence of pahole tool, which will convert
354	  DWARF type info into equivalent deduplicated BTF type info.
355
356config PAHOLE_HAS_SPLIT_BTF
357	def_bool PAHOLE_VERSION >= 119
358
359config PAHOLE_HAS_BTF_TAG
360	def_bool PAHOLE_VERSION >= 123
361	depends on CC_IS_CLANG
362	help
363	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
364	  btf_decl_tag) or not. Currently only clang compiler implements
365	  these attributes, so make the config depend on CC_IS_CLANG.
366
367config DEBUG_INFO_BTF_MODULES
368	def_bool y
369	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
370	help
371	  Generate compact split BTF type information for kernel modules.
372
373config MODULE_ALLOW_BTF_MISMATCH
374	bool "Allow loading modules with non-matching BTF type info"
375	depends on DEBUG_INFO_BTF_MODULES
376	help
377	  For modules whose split BTF does not match vmlinux, load without
378	  BTF rather than refusing to load. The default behavior with
379	  module BTF enabled is to reject modules with such mismatches;
380	  this option will still load module BTF where possible but ignore
381	  it when a mismatch is found.
382
383config GDB_SCRIPTS
384	bool "Provide GDB scripts for kernel debugging"
385	help
386	  This creates the required links to GDB helper scripts in the
387	  build directory. If you load vmlinux into gdb, the helper
388	  scripts will be automatically imported by gdb as well, and
389	  additional functions are available to analyze a Linux kernel
390	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
391	  for further details.
392
393endif # DEBUG_INFO
394
395config FRAME_WARN
396	int "Warn for stack frames larger than"
397	range 0 8192
398	default 0 if KMSAN
399	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
400	default 2048 if PARISC
401	default 1536 if (!64BIT && XTENSA)
402	default 1280 if KASAN && !64BIT
403	default 1024 if !64BIT
404	default 2048 if 64BIT
405	help
406	  Tell the compiler to warn at build time for stack frames larger than this.
407	  Setting this too low will cause a lot of warnings.
408	  Setting it to 0 disables the warning.
409
410config STRIP_ASM_SYMS
411	bool "Strip assembler-generated symbols during link"
412	default n
413	help
414	  Strip internal assembler-generated symbols during a link (symbols
415	  that look like '.Lxxx') so they don't pollute the output of
416	  get_wchan() and suchlike.
417
418config READABLE_ASM
419	bool "Generate readable assembler code"
420	depends on DEBUG_KERNEL
421	depends on CC_IS_GCC
422	help
423	  Disable some compiler optimizations that tend to generate human unreadable
424	  assembler output. This may make the kernel slightly slower, but it helps
425	  to keep kernel developers who have to stare a lot at assembler listings
426	  sane.
427
428config HEADERS_INSTALL
429	bool "Install uapi headers to usr/include"
430	depends on !UML
431	help
432	  This option will install uapi headers (headers exported to user-space)
433	  into the usr/include directory for use during the kernel build.
434	  This is unneeded for building the kernel itself, but needed for some
435	  user-space program samples. It is also needed by some features such
436	  as uapi header sanity checks.
437
438config DEBUG_SECTION_MISMATCH
439	bool "Enable full Section mismatch analysis"
440	depends on CC_IS_GCC
441	help
442	  The section mismatch analysis checks if there are illegal
443	  references from one section to another section.
444	  During linktime or runtime, some sections are dropped;
445	  any use of code/data previously in these sections would
446	  most likely result in an oops.
447	  In the code, functions and variables are annotated with
448	  __init,, etc. (see the full list in include/linux/init.h),
449	  which results in the code/data being placed in specific sections.
450	  The section mismatch analysis is always performed after a full
451	  kernel build, and enabling this option causes the following
452	  additional step to occur:
453	  - Add the option -fno-inline-functions-called-once to gcc commands.
454	    When inlining a function annotated with __init in a non-init
455	    function, we would lose the section information and thus
456	    the analysis would not catch the illegal reference.
457	    This option tells gcc to inline less (but it does result in
458	    a larger kernel).
459
460config SECTION_MISMATCH_WARN_ONLY
461	bool "Make section mismatch errors non-fatal"
462	default y
463	help
464	  If you say N here, the build process will fail if there are any
465	  section mismatch, instead of just throwing warnings.
466
467	  If unsure, say Y.
468
469config DEBUG_FORCE_FUNCTION_ALIGN_64B
470	bool "Force all function address 64B aligned"
471	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC)
472	select FUNCTION_ALIGNMENT_64B
473	help
474	  There are cases that a commit from one domain changes the function
475	  address alignment of other domains, and cause magic performance
476	  bump (regression or improvement). Enable this option will help to
477	  verify if the bump is caused by function alignment changes, while
478	  it will slightly increase the kernel size and affect icache usage.
479
480	  It is mainly for debug and performance tuning use.
481
482#
483# Select this config option from the architecture Kconfig, if it
484# is preferred to always offer frame pointers as a config
485# option on the architecture (regardless of KERNEL_DEBUG):
486#
487config ARCH_WANT_FRAME_POINTERS
488	bool
489
490config FRAME_POINTER
491	bool "Compile the kernel with frame pointers"
492	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
493	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
494	help
495	  If you say Y here the resulting kernel image will be slightly
496	  larger and slower, but it gives very useful debugging information
497	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
498
499config OBJTOOL
500	bool
501
502config STACK_VALIDATION
503	bool "Compile-time stack metadata validation"
504	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
505	select OBJTOOL
506	default n
507	help
508	  Validate frame pointer rules at compile-time.  This helps ensure that
509	  runtime stack traces are more reliable.
510
511	  For more information, see
512	  tools/objtool/Documentation/objtool.txt.
513
514config NOINSTR_VALIDATION
515	bool
516	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
517	select OBJTOOL
518	default y
519
520config VMLINUX_MAP
521	bool "Generate vmlinux.map file when linking"
522	depends on EXPERT
523	help
524	  Selecting this option will pass "-Map=vmlinux.map" to ld
525	  when linking vmlinux. That file can be useful for verifying
526	  and debugging magic section games, and for seeing which
527	  pieces of code get eliminated with
528	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
529
530config DEBUG_FORCE_WEAK_PER_CPU
531	bool "Force weak per-cpu definitions"
532	depends on DEBUG_KERNEL
533	help
534	  s390 and alpha require percpu variables in modules to be
535	  defined weak to work around addressing range issue which
536	  puts the following two restrictions on percpu variable
537	  definitions.
538
539	  1. percpu symbols must be unique whether static or not
540	  2. percpu variables can't be defined inside a function
541
542	  To ensure that generic code follows the above rules, this
543	  option forces all percpu variables to be defined as weak.
544
545endmenu # "Compiler options"
546
547menu "Generic Kernel Debugging Instruments"
548
549config MAGIC_SYSRQ
550	bool "Magic SysRq key"
551	depends on !UML
552	help
553	  If you say Y here, you will have some control over the system even
554	  if the system crashes for example during kernel debugging (e.g., you
555	  will be able to flush the buffer cache to disk, reboot the system
556	  immediately or dump some status information). This is accomplished
557	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
558	  also works on a serial console (on PC hardware at least), if you
559	  send a BREAK and then within 5 seconds a command keypress. The
560	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
561	  Don't say Y unless you really know what this hack does.
562
563config MAGIC_SYSRQ_DEFAULT_ENABLE
564	hex "Enable magic SysRq key functions by default"
565	depends on MAGIC_SYSRQ
566	default 0x1
567	help
568	  Specifies which SysRq key functions are enabled by default.
569	  This may be set to 1 or 0 to enable or disable them all, or
570	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
571
572config MAGIC_SYSRQ_SERIAL
573	bool "Enable magic SysRq key over serial"
574	depends on MAGIC_SYSRQ
575	default y
576	help
577	  Many embedded boards have a disconnected TTL level serial which can
578	  generate some garbage that can lead to spurious false sysrq detects.
579	  This option allows you to decide whether you want to enable the
580	  magic SysRq key.
581
582config MAGIC_SYSRQ_SERIAL_SEQUENCE
583	string "Char sequence that enables magic SysRq over serial"
584	depends on MAGIC_SYSRQ_SERIAL
585	default ""
586	help
587	  Specifies a sequence of characters that can follow BREAK to enable
588	  SysRq on a serial console.
589
590	  If unsure, leave an empty string and the option will not be enabled.
591
592config DEBUG_FS
593	bool "Debug Filesystem"
594	help
595	  debugfs is a virtual file system that kernel developers use to put
596	  debugging files into.  Enable this option to be able to read and
597	  write to these files.
598
599	  For detailed documentation on the debugfs API, see
600	  Documentation/filesystems/.
601
602	  If unsure, say N.
603
604choice
605	prompt "Debugfs default access"
606	depends on DEBUG_FS
607	default DEBUG_FS_ALLOW_ALL
608	help
609	  This selects the default access restrictions for debugfs.
610	  It can be overridden with kernel command line option
611	  debugfs=[on,no-mount,off]. The restrictions apply for API access
612	  and filesystem registration.
613
614config DEBUG_FS_ALLOW_ALL
615	bool "Access normal"
616	help
617	  No restrictions apply. Both API and filesystem registration
618	  is on. This is the normal default operation.
619
620config DEBUG_FS_DISALLOW_MOUNT
621	bool "Do not register debugfs as filesystem"
622	help
623	  The API is open but filesystem is not loaded. Clients can still do
624	  their work and read with debug tools that do not need
625	  debugfs filesystem.
626
627config DEBUG_FS_ALLOW_NONE
628	bool "No access"
629	help
630	  Access is off. Clients get -PERM when trying to create nodes in
631	  debugfs tree and debugfs is not registered as a filesystem.
632	  Client can then back-off or continue without debugfs access.
633
634endchoice
635
636source "lib/Kconfig.kgdb"
637source "lib/Kconfig.ubsan"
638source "lib/Kconfig.kcsan"
639
640endmenu
641
642menu "Networking Debugging"
643
644source "net/Kconfig.debug"
645
646endmenu # "Networking Debugging"
647
648menu "Memory Debugging"
649
650source "mm/Kconfig.debug"
651
652config DEBUG_OBJECTS
653	bool "Debug object operations"
654	depends on DEBUG_KERNEL
655	help
656	  If you say Y here, additional code will be inserted into the
657	  kernel to track the life time of various objects and validate
658	  the operations on those objects.
659
660config DEBUG_OBJECTS_SELFTEST
661	bool "Debug objects selftest"
662	depends on DEBUG_OBJECTS
663	help
664	  This enables the selftest of the object debug code.
665
666config DEBUG_OBJECTS_FREE
667	bool "Debug objects in freed memory"
668	depends on DEBUG_OBJECTS
669	help
670	  This enables checks whether a k/v free operation frees an area
671	  which contains an object which has not been deactivated
672	  properly. This can make kmalloc/kfree-intensive workloads
673	  much slower.
674
675config DEBUG_OBJECTS_TIMERS
676	bool "Debug timer objects"
677	depends on DEBUG_OBJECTS
678	help
679	  If you say Y here, additional code will be inserted into the
680	  timer routines to track the life time of timer objects and
681	  validate the timer operations.
682
683config DEBUG_OBJECTS_WORK
684	bool "Debug work objects"
685	depends on DEBUG_OBJECTS
686	help
687	  If you say Y here, additional code will be inserted into the
688	  work queue routines to track the life time of work objects and
689	  validate the work operations.
690
691config DEBUG_OBJECTS_RCU_HEAD
692	bool "Debug RCU callbacks objects"
693	depends on DEBUG_OBJECTS
694	help
695	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
696
697config DEBUG_OBJECTS_PERCPU_COUNTER
698	bool "Debug percpu counter objects"
699	depends on DEBUG_OBJECTS
700	help
701	  If you say Y here, additional code will be inserted into the
702	  percpu counter routines to track the life time of percpu counter
703	  objects and validate the percpu counter operations.
704
705config DEBUG_OBJECTS_ENABLE_DEFAULT
706	int "debug_objects bootup default value (0-1)"
707	range 0 1
708	default "1"
709	depends on DEBUG_OBJECTS
710	help
711	  Debug objects boot parameter default value
712
713config SHRINKER_DEBUG
714	bool "Enable shrinker debugging support"
715	depends on DEBUG_FS
716	help
717	  Say Y to enable the shrinker debugfs interface which provides
718	  visibility into the kernel memory shrinkers subsystem.
719	  Disable it to avoid an extra memory footprint.
720
721config HAVE_DEBUG_KMEMLEAK
722	bool
723
724config DEBUG_KMEMLEAK
725	bool "Kernel memory leak detector"
726	depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
727	select DEBUG_FS
728	select STACKTRACE if STACKTRACE_SUPPORT
729	select KALLSYMS
730	select CRC32
731	select STACKDEPOT
732	help
733	  Say Y here if you want to enable the memory leak
734	  detector. The memory allocation/freeing is traced in a way
735	  similar to the Boehm's conservative garbage collector, the
736	  difference being that the orphan objects are not freed but
737	  only shown in /sys/kernel/debug/kmemleak. Enabling this
738	  feature will introduce an overhead to memory
739	  allocations. See Documentation/dev-tools/kmemleak.rst for more
740	  details.
741
742	  Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
743	  of finding leaks due to the slab objects poisoning.
744
745	  In order to access the kmemleak file, debugfs needs to be
746	  mounted (usually at /sys/kernel/debug).
747
748config DEBUG_KMEMLEAK_MEM_POOL_SIZE
749	int "Kmemleak memory pool size"
750	depends on DEBUG_KMEMLEAK
751	range 200 1000000
752	default 16000
753	help
754	  Kmemleak must track all the memory allocations to avoid
755	  reporting false positives. Since memory may be allocated or
756	  freed before kmemleak is fully initialised, use a static pool
757	  of metadata objects to track such callbacks. After kmemleak is
758	  fully initialised, this memory pool acts as an emergency one
759	  if slab allocations fail.
760
761config DEBUG_KMEMLEAK_TEST
762	tristate "Simple test for the kernel memory leak detector"
763	depends on DEBUG_KMEMLEAK && m
764	help
765	  This option enables a module that explicitly leaks memory.
766
767	  If unsure, say N.
768
769config DEBUG_KMEMLEAK_DEFAULT_OFF
770	bool "Default kmemleak to off"
771	depends on DEBUG_KMEMLEAK
772	help
773	  Say Y here to disable kmemleak by default. It can then be enabled
774	  on the command line via kmemleak=on.
775
776config DEBUG_KMEMLEAK_AUTO_SCAN
777	bool "Enable kmemleak auto scan thread on boot up"
778	default y
779	depends on DEBUG_KMEMLEAK
780	help
781	  Depending on the cpu, kmemleak scan may be cpu intensive and can
782	  stall user tasks at times. This option enables/disables automatic
783	  kmemleak scan at boot up.
784
785	  Say N here to disable kmemleak auto scan thread to stop automatic
786	  scanning. Disabling this option disables automatic reporting of
787	  memory leaks.
788
789	  If unsure, say Y.
790
791config DEBUG_STACK_USAGE
792	bool "Stack utilization instrumentation"
793	depends on DEBUG_KERNEL && !IA64
794	help
795	  Enables the display of the minimum amount of free stack which each
796	  task has ever had available in the sysrq-T and sysrq-P debug output.
797
798	  This option will slow down process creation somewhat.
799
800config SCHED_STACK_END_CHECK
801	bool "Detect stack corruption on calls to schedule()"
802	depends on DEBUG_KERNEL
803	default n
804	help
805	  This option checks for a stack overrun on calls to schedule().
806	  If the stack end location is found to be over written always panic as
807	  the content of the corrupted region can no longer be trusted.
808	  This is to ensure no erroneous behaviour occurs which could result in
809	  data corruption or a sporadic crash at a later stage once the region
810	  is examined. The runtime overhead introduced is minimal.
811
812config ARCH_HAS_DEBUG_VM_PGTABLE
813	bool
814	help
815	  An architecture should select this when it can successfully
816	  build and run DEBUG_VM_PGTABLE.
817
818config DEBUG_VM_IRQSOFF
819	def_bool DEBUG_VM && !PREEMPT_RT
820
821config DEBUG_VM
822	bool "Debug VM"
823	depends on DEBUG_KERNEL
824	help
825	  Enable this to turn on extended checks in the virtual-memory system
826	  that may impact performance.
827
828	  If unsure, say N.
829
830config DEBUG_VM_MAPLE_TREE
831	bool "Debug VM maple trees"
832	depends on DEBUG_VM
833	select DEBUG_MAPLE_TREE
834	help
835	  Enable VM maple tree debugging information and extra validations.
836
837	  If unsure, say N.
838
839config DEBUG_VM_RB
840	bool "Debug VM red-black trees"
841	depends on DEBUG_VM
842	help
843	  Enable VM red-black tree debugging information and extra validations.
844
845	  If unsure, say N.
846
847config DEBUG_VM_PGFLAGS
848	bool "Debug page-flags operations"
849	depends on DEBUG_VM
850	help
851	  Enables extra validation on page flags operations.
852
853	  If unsure, say N.
854
855config DEBUG_VM_PGTABLE
856	bool "Debug arch page table for semantics compliance"
857	depends on MMU
858	depends on ARCH_HAS_DEBUG_VM_PGTABLE
859	default y if DEBUG_VM
860	help
861	  This option provides a debug method which can be used to test
862	  architecture page table helper functions on various platforms in
863	  verifying if they comply with expected generic MM semantics. This
864	  will help architecture code in making sure that any changes or
865	  new additions of these helpers still conform to expected
866	  semantics of the generic MM. Platforms will have to opt in for
867	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
868
869	  If unsure, say N.
870
871config ARCH_HAS_DEBUG_VIRTUAL
872	bool
873
874config DEBUG_VIRTUAL
875	bool "Debug VM translations"
876	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
877	help
878	  Enable some costly sanity checks in virtual to page code. This can
879	  catch mistakes with virt_to_page() and friends.
880
881	  If unsure, say N.
882
883config DEBUG_NOMMU_REGIONS
884	bool "Debug the global anon/private NOMMU mapping region tree"
885	depends on DEBUG_KERNEL && !MMU
886	help
887	  This option causes the global tree of anonymous and private mapping
888	  regions to be regularly checked for invalid topology.
889
890config DEBUG_MEMORY_INIT
891	bool "Debug memory initialisation" if EXPERT
892	default !EXPERT
893	help
894	  Enable this for additional checks during memory initialisation.
895	  The sanity checks verify aspects of the VM such as the memory model
896	  and other information provided by the architecture. Verbose
897	  information will be printed at KERN_DEBUG loglevel depending
898	  on the mminit_loglevel= command-line option.
899
900	  If unsure, say Y
901
902config MEMORY_NOTIFIER_ERROR_INJECT
903	tristate "Memory hotplug notifier error injection module"
904	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
905	help
906	  This option provides the ability to inject artificial errors to
907	  memory hotplug notifier chain callbacks.  It is controlled through
908	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
909
910	  If the notifier call chain should be failed with some events
911	  notified, write the error code to "actions/<notifier event>/error".
912
913	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
914
915	  # cd /sys/kernel/debug/notifier-error-inject/memory
916	  # echo -12 > actions/MEM_GOING_OFFLINE/error
917	  # echo offline > /sys/devices/system/memory/memoryXXX/state
918	  bash: echo: write error: Cannot allocate memory
919
920	  To compile this code as a module, choose M here: the module will
921	  be called memory-notifier-error-inject.
922
923	  If unsure, say N.
924
925config DEBUG_PER_CPU_MAPS
926	bool "Debug access to per_cpu maps"
927	depends on DEBUG_KERNEL
928	depends on SMP
929	help
930	  Say Y to verify that the per_cpu map being accessed has
931	  been set up. This adds a fair amount of code to kernel memory
932	  and decreases performance.
933
934	  Say N if unsure.
935
936config DEBUG_KMAP_LOCAL
937	bool "Debug kmap_local temporary mappings"
938	depends on DEBUG_KERNEL && KMAP_LOCAL
939	help
940	  This option enables additional error checking for the kmap_local
941	  infrastructure.  Disable for production use.
942
943config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
944	bool
945
946config DEBUG_KMAP_LOCAL_FORCE_MAP
947	bool "Enforce kmap_local temporary mappings"
948	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
949	select KMAP_LOCAL
950	select DEBUG_KMAP_LOCAL
951	help
952	  This option enforces temporary mappings through the kmap_local
953	  mechanism for non-highmem pages and on non-highmem systems.
954	  Disable this for production systems!
955
956config DEBUG_HIGHMEM
957	bool "Highmem debugging"
958	depends on DEBUG_KERNEL && HIGHMEM
959	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
960	select DEBUG_KMAP_LOCAL
961	help
962	  This option enables additional error checking for high memory
963	  systems.  Disable for production systems.
964
965config HAVE_DEBUG_STACKOVERFLOW
966	bool
967
968config DEBUG_STACKOVERFLOW
969	bool "Check for stack overflows"
970	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
971	help
972	  Say Y here if you want to check for overflows of kernel, IRQ
973	  and exception stacks (if your architecture uses them). This
974	  option will show detailed messages if free stack space drops
975	  below a certain limit.
976
977	  These kinds of bugs usually occur when call-chains in the
978	  kernel get too deep, especially when interrupts are
979	  involved.
980
981	  Use this in cases where you see apparently random memory
982	  corruption, especially if it appears in 'struct thread_info'
983
984	  If in doubt, say "N".
985
986source "lib/Kconfig.kasan"
987source "lib/Kconfig.kfence"
988source "lib/Kconfig.kmsan"
989
990endmenu # "Memory Debugging"
991
992config DEBUG_SHIRQ
993	bool "Debug shared IRQ handlers"
994	depends on DEBUG_KERNEL
995	help
996	  Enable this to generate a spurious interrupt just before a shared
997	  interrupt handler is deregistered (generating one when registering
998	  is currently disabled). Drivers need to handle this correctly. Some
999	  don't and need to be caught.
1000
1001menu "Debug Oops, Lockups and Hangs"
1002
1003config PANIC_ON_OOPS
1004	bool "Panic on Oops"
1005	help
1006	  Say Y here to enable the kernel to panic when it oopses. This
1007	  has the same effect as setting oops=panic on the kernel command
1008	  line.
1009
1010	  This feature is useful to ensure that the kernel does not do
1011	  anything erroneous after an oops which could result in data
1012	  corruption or other issues.
1013
1014	  Say N if unsure.
1015
1016config PANIC_ON_OOPS_VALUE
1017	int
1018	range 0 1
1019	default 0 if !PANIC_ON_OOPS
1020	default 1 if PANIC_ON_OOPS
1021
1022config PANIC_TIMEOUT
1023	int "panic timeout"
1024	default 0
1025	help
1026	  Set the timeout value (in seconds) until a reboot occurs when
1027	  the kernel panics. If n = 0, then we wait forever. A timeout
1028	  value n > 0 will wait n seconds before rebooting, while a timeout
1029	  value n < 0 will reboot immediately.
1030
1031config LOCKUP_DETECTOR
1032	bool
1033
1034config SOFTLOCKUP_DETECTOR
1035	bool "Detect Soft Lockups"
1036	depends on DEBUG_KERNEL && !S390
1037	select LOCKUP_DETECTOR
1038	help
1039	  Say Y here to enable the kernel to act as a watchdog to detect
1040	  soft lockups.
1041
1042	  Softlockups are bugs that cause the kernel to loop in kernel
1043	  mode for more than 20 seconds, without giving other tasks a
1044	  chance to run.  The current stack trace is displayed upon
1045	  detection and the system will stay locked up.
1046
1047config BOOTPARAM_SOFTLOCKUP_PANIC
1048	bool "Panic (Reboot) On Soft Lockups"
1049	depends on SOFTLOCKUP_DETECTOR
1050	help
1051	  Say Y here to enable the kernel to panic on "soft lockups",
1052	  which are bugs that cause the kernel to loop in kernel
1053	  mode for more than 20 seconds (configurable using the watchdog_thresh
1054	  sysctl), without giving other tasks a chance to run.
1055
1056	  The panic can be used in combination with panic_timeout,
1057	  to cause the system to reboot automatically after a
1058	  lockup has been detected. This feature is useful for
1059	  high-availability systems that have uptime guarantees and
1060	  where a lockup must be resolved ASAP.
1061
1062	  Say N if unsure.
1063
1064config HARDLOCKUP_DETECTOR_PERF
1065	bool
1066	select SOFTLOCKUP_DETECTOR
1067
1068#
1069# Enables a timestamp based low pass filter to compensate for perf based
1070# hard lockup detection which runs too fast due to turbo modes.
1071#
1072config HARDLOCKUP_CHECK_TIMESTAMP
1073	bool
1074
1075#
1076# arch/ can define HAVE_HARDLOCKUP_DETECTOR_ARCH to provide their own hard
1077# lockup detector rather than the perf based detector.
1078#
1079config HARDLOCKUP_DETECTOR
1080	bool "Detect Hard Lockups"
1081	depends on DEBUG_KERNEL && !S390
1082	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
1083	select LOCKUP_DETECTOR
1084	select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
1085	help
1086	  Say Y here to enable the kernel to act as a watchdog to detect
1087	  hard lockups.
1088
1089	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1090	  for more than 10 seconds, without letting other interrupts have a
1091	  chance to run.  The current stack trace is displayed upon detection
1092	  and the system will stay locked up.
1093
1094config BOOTPARAM_HARDLOCKUP_PANIC
1095	bool "Panic (Reboot) On Hard Lockups"
1096	depends on HARDLOCKUP_DETECTOR
1097	help
1098	  Say Y here to enable the kernel to panic on "hard lockups",
1099	  which are bugs that cause the kernel to loop in kernel
1100	  mode with interrupts disabled for more than 10 seconds (configurable
1101	  using the watchdog_thresh sysctl).
1102
1103	  Say N if unsure.
1104
1105config DETECT_HUNG_TASK
1106	bool "Detect Hung Tasks"
1107	depends on DEBUG_KERNEL
1108	default SOFTLOCKUP_DETECTOR
1109	help
1110	  Say Y here to enable the kernel to detect "hung tasks",
1111	  which are bugs that cause the task to be stuck in
1112	  uninterruptible "D" state indefinitely.
1113
1114	  When a hung task is detected, the kernel will print the
1115	  current stack trace (which you should report), but the
1116	  task will stay in uninterruptible state. If lockdep is
1117	  enabled then all held locks will also be reported. This
1118	  feature has negligible overhead.
1119
1120config DEFAULT_HUNG_TASK_TIMEOUT
1121	int "Default timeout for hung task detection (in seconds)"
1122	depends on DETECT_HUNG_TASK
1123	default 120
1124	help
1125	  This option controls the default timeout (in seconds) used
1126	  to determine when a task has become non-responsive and should
1127	  be considered hung.
1128
1129	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1130	  sysctl or by writing a value to
1131	  /proc/sys/kernel/hung_task_timeout_secs.
1132
1133	  A timeout of 0 disables the check.  The default is two minutes.
1134	  Keeping the default should be fine in most cases.
1135
1136config BOOTPARAM_HUNG_TASK_PANIC
1137	bool "Panic (Reboot) On Hung Tasks"
1138	depends on DETECT_HUNG_TASK
1139	help
1140	  Say Y here to enable the kernel to panic on "hung tasks",
1141	  which are bugs that cause the kernel to leave a task stuck
1142	  in uninterruptible "D" state.
1143
1144	  The panic can be used in combination with panic_timeout,
1145	  to cause the system to reboot automatically after a
1146	  hung task has been detected. This feature is useful for
1147	  high-availability systems that have uptime guarantees and
1148	  where a hung tasks must be resolved ASAP.
1149
1150	  Say N if unsure.
1151
1152config WQ_WATCHDOG
1153	bool "Detect Workqueue Stalls"
1154	depends on DEBUG_KERNEL
1155	help
1156	  Say Y here to enable stall detection on workqueues.  If a
1157	  worker pool doesn't make forward progress on a pending work
1158	  item for over a given amount of time, 30s by default, a
1159	  warning message is printed along with dump of workqueue
1160	  state.  This can be configured through kernel parameter
1161	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1162
1163config TEST_LOCKUP
1164	tristate "Test module to generate lockups"
1165	depends on m
1166	help
1167	  This builds the "test_lockup" module that helps to make sure
1168	  that watchdogs and lockup detectors are working properly.
1169
1170	  Depending on module parameters it could emulate soft or hard
1171	  lockup, "hung task", or locking arbitrary lock for a long time.
1172	  Also it could generate series of lockups with cooling-down periods.
1173
1174	  If unsure, say N.
1175
1176endmenu # "Debug lockups and hangs"
1177
1178menu "Scheduler Debugging"
1179
1180config SCHED_DEBUG
1181	bool "Collect scheduler debugging info"
1182	depends on DEBUG_KERNEL && PROC_FS
1183	default y
1184	help
1185	  If you say Y here, the /proc/sched_debug file will be provided
1186	  that can help debug the scheduler. The runtime overhead of this
1187	  option is minimal.
1188
1189config SCHED_INFO
1190	bool
1191	default n
1192
1193config SCHEDSTATS
1194	bool "Collect scheduler statistics"
1195	depends on DEBUG_KERNEL && PROC_FS
1196	select SCHED_INFO
1197	help
1198	  If you say Y here, additional code will be inserted into the
1199	  scheduler and related routines to collect statistics about
1200	  scheduler behavior and provide them in /proc/schedstat.  These
1201	  stats may be useful for both tuning and debugging the scheduler
1202	  If you aren't debugging the scheduler or trying to tune a specific
1203	  application, you can say N to avoid the very slight overhead
1204	  this adds.
1205
1206endmenu
1207
1208config DEBUG_TIMEKEEPING
1209	bool "Enable extra timekeeping sanity checking"
1210	help
1211	  This option will enable additional timekeeping sanity checks
1212	  which may be helpful when diagnosing issues where timekeeping
1213	  problems are suspected.
1214
1215	  This may include checks in the timekeeping hotpaths, so this
1216	  option may have a (very small) performance impact to some
1217	  workloads.
1218
1219	  If unsure, say N.
1220
1221config DEBUG_PREEMPT
1222	bool "Debug preemptible kernel"
1223	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1224	default y
1225	help
1226	  If you say Y here then the kernel will use a debug variant of the
1227	  commonly used smp_processor_id() function and will print warnings
1228	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1229	  will detect preemption count underflows.
1230
1231menu "Lock Debugging (spinlocks, mutexes, etc...)"
1232
1233config LOCK_DEBUGGING_SUPPORT
1234	bool
1235	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1236	default y
1237
1238config PROVE_LOCKING
1239	bool "Lock debugging: prove locking correctness"
1240	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1241	select LOCKDEP
1242	select DEBUG_SPINLOCK
1243	select DEBUG_MUTEXES if !PREEMPT_RT
1244	select DEBUG_RT_MUTEXES if RT_MUTEXES
1245	select DEBUG_RWSEMS
1246	select DEBUG_WW_MUTEX_SLOWPATH
1247	select DEBUG_LOCK_ALLOC
1248	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1249	select TRACE_IRQFLAGS
1250	default n
1251	help
1252	 This feature enables the kernel to prove that all locking
1253	 that occurs in the kernel runtime is mathematically
1254	 correct: that under no circumstance could an arbitrary (and
1255	 not yet triggered) combination of observed locking
1256	 sequences (on an arbitrary number of CPUs, running an
1257	 arbitrary number of tasks and interrupt contexts) cause a
1258	 deadlock.
1259
1260	 In short, this feature enables the kernel to report locking
1261	 related deadlocks before they actually occur.
1262
1263	 The proof does not depend on how hard and complex a
1264	 deadlock scenario would be to trigger: how many
1265	 participant CPUs, tasks and irq-contexts would be needed
1266	 for it to trigger. The proof also does not depend on
1267	 timing: if a race and a resulting deadlock is possible
1268	 theoretically (no matter how unlikely the race scenario
1269	 is), it will be proven so and will immediately be
1270	 reported by the kernel (once the event is observed that
1271	 makes the deadlock theoretically possible).
1272
1273	 If a deadlock is impossible (i.e. the locking rules, as
1274	 observed by the kernel, are mathematically correct), the
1275	 kernel reports nothing.
1276
1277	 NOTE: this feature can also be enabled for rwlocks, mutexes
1278	 and rwsems - in which case all dependencies between these
1279	 different locking variants are observed and mapped too, and
1280	 the proof of observed correctness is also maintained for an
1281	 arbitrary combination of these separate locking variants.
1282
1283	 For more details, see Documentation/locking/lockdep-design.rst.
1284
1285config PROVE_RAW_LOCK_NESTING
1286	bool "Enable raw_spinlock - spinlock nesting checks"
1287	depends on PROVE_LOCKING
1288	default n
1289	help
1290	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1291	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1292	 not violated.
1293
1294	 NOTE: There are known nesting problems. So if you enable this
1295	 option expect lockdep splats until these problems have been fully
1296	 addressed which is work in progress. This config switch allows to
1297	 identify and analyze these problems. It will be removed and the
1298	 check permanently enabled once the main issues have been fixed.
1299
1300	 If unsure, select N.
1301
1302config LOCK_STAT
1303	bool "Lock usage statistics"
1304	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1305	select LOCKDEP
1306	select DEBUG_SPINLOCK
1307	select DEBUG_MUTEXES if !PREEMPT_RT
1308	select DEBUG_RT_MUTEXES if RT_MUTEXES
1309	select DEBUG_LOCK_ALLOC
1310	default n
1311	help
1312	 This feature enables tracking lock contention points
1313
1314	 For more details, see Documentation/locking/lockstat.rst
1315
1316	 This also enables lock events required by "perf lock",
1317	 subcommand of perf.
1318	 If you want to use "perf lock", you also need to turn on
1319	 CONFIG_EVENT_TRACING.
1320
1321	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1322	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1323
1324config DEBUG_RT_MUTEXES
1325	bool "RT Mutex debugging, deadlock detection"
1326	depends on DEBUG_KERNEL && RT_MUTEXES
1327	help
1328	 This allows rt mutex semantics violations and rt mutex related
1329	 deadlocks (lockups) to be detected and reported automatically.
1330
1331config DEBUG_SPINLOCK
1332	bool "Spinlock and rw-lock debugging: basic checks"
1333	depends on DEBUG_KERNEL
1334	select UNINLINE_SPIN_UNLOCK
1335	help
1336	  Say Y here and build SMP to catch missing spinlock initialization
1337	  and certain other kinds of spinlock errors commonly made.  This is
1338	  best used in conjunction with the NMI watchdog so that spinlock
1339	  deadlocks are also debuggable.
1340
1341config DEBUG_MUTEXES
1342	bool "Mutex debugging: basic checks"
1343	depends on DEBUG_KERNEL && !PREEMPT_RT
1344	help
1345	 This feature allows mutex semantics violations to be detected and
1346	 reported.
1347
1348config DEBUG_WW_MUTEX_SLOWPATH
1349	bool "Wait/wound mutex debugging: Slowpath testing"
1350	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1351	select DEBUG_LOCK_ALLOC
1352	select DEBUG_SPINLOCK
1353	select DEBUG_MUTEXES if !PREEMPT_RT
1354	select DEBUG_RT_MUTEXES if PREEMPT_RT
1355	help
1356	 This feature enables slowpath testing for w/w mutex users by
1357	 injecting additional -EDEADLK wound/backoff cases. Together with
1358	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1359	 will test all possible w/w mutex interface abuse with the
1360	 exception of simply not acquiring all the required locks.
1361	 Note that this feature can introduce significant overhead, so
1362	 it really should not be enabled in a production or distro kernel,
1363	 even a debug kernel.  If you are a driver writer, enable it.  If
1364	 you are a distro, do not.
1365
1366config DEBUG_RWSEMS
1367	bool "RW Semaphore debugging: basic checks"
1368	depends on DEBUG_KERNEL
1369	help
1370	  This debugging feature allows mismatched rw semaphore locks
1371	  and unlocks to be detected and reported.
1372
1373config DEBUG_LOCK_ALLOC
1374	bool "Lock debugging: detect incorrect freeing of live locks"
1375	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1376	select DEBUG_SPINLOCK
1377	select DEBUG_MUTEXES if !PREEMPT_RT
1378	select DEBUG_RT_MUTEXES if RT_MUTEXES
1379	select LOCKDEP
1380	help
1381	 This feature will check whether any held lock (spinlock, rwlock,
1382	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1383	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1384	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1385	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1386	 held during task exit.
1387
1388config LOCKDEP
1389	bool
1390	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1391	select STACKTRACE
1392	select KALLSYMS
1393	select KALLSYMS_ALL
1394
1395config LOCKDEP_SMALL
1396	bool
1397
1398config LOCKDEP_BITS
1399	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1400	depends on LOCKDEP && !LOCKDEP_SMALL
1401	range 10 30
1402	default 15
1403	help
1404	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1405
1406config LOCKDEP_CHAINS_BITS
1407	int "Bitsize for MAX_LOCKDEP_CHAINS"
1408	depends on LOCKDEP && !LOCKDEP_SMALL
1409	range 10 30
1410	default 16
1411	help
1412	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1413
1414config LOCKDEP_STACK_TRACE_BITS
1415	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1416	depends on LOCKDEP && !LOCKDEP_SMALL
1417	range 10 30
1418	default 19
1419	help
1420	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1421
1422config LOCKDEP_STACK_TRACE_HASH_BITS
1423	int "Bitsize for STACK_TRACE_HASH_SIZE"
1424	depends on LOCKDEP && !LOCKDEP_SMALL
1425	range 10 30
1426	default 14
1427	help
1428	  Try increasing this value if you need large MAX_STACK_TRACE_ENTRIES.
1429
1430config LOCKDEP_CIRCULAR_QUEUE_BITS
1431	int "Bitsize for elements in circular_queue struct"
1432	depends on LOCKDEP
1433	range 10 30
1434	default 12
1435	help
1436	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1437
1438config DEBUG_LOCKDEP
1439	bool "Lock dependency engine debugging"
1440	depends on DEBUG_KERNEL && LOCKDEP
1441	select DEBUG_IRQFLAGS
1442	help
1443	  If you say Y here, the lock dependency engine will do
1444	  additional runtime checks to debug itself, at the price
1445	  of more runtime overhead.
1446
1447config DEBUG_ATOMIC_SLEEP
1448	bool "Sleep inside atomic section checking"
1449	select PREEMPT_COUNT
1450	depends on DEBUG_KERNEL
1451	depends on !ARCH_NO_PREEMPT
1452	help
1453	  If you say Y here, various routines which may sleep will become very
1454	  noisy if they are called inside atomic sections: when a spinlock is
1455	  held, inside an rcu read side critical section, inside preempt disabled
1456	  sections, inside an interrupt, etc...
1457
1458config DEBUG_LOCKING_API_SELFTESTS
1459	bool "Locking API boot-time self-tests"
1460	depends on DEBUG_KERNEL
1461	help
1462	  Say Y here if you want the kernel to run a short self-test during
1463	  bootup. The self-test checks whether common types of locking bugs
1464	  are detected by debugging mechanisms or not. (if you disable
1465	  lock debugging then those bugs won't be detected of course.)
1466	  The following locking APIs are covered: spinlocks, rwlocks,
1467	  mutexes and rwsems.
1468
1469config LOCK_TORTURE_TEST
1470	tristate "torture tests for locking"
1471	depends on DEBUG_KERNEL
1472	select TORTURE_TEST
1473	help
1474	  This option provides a kernel module that runs torture tests
1475	  on kernel locking primitives.  The kernel module may be built
1476	  after the fact on the running kernel to be tested, if desired.
1477
1478	  Say Y here if you want kernel locking-primitive torture tests
1479	  to be built into the kernel.
1480	  Say M if you want these torture tests to build as a module.
1481	  Say N if you are unsure.
1482
1483config WW_MUTEX_SELFTEST
1484	tristate "Wait/wound mutex selftests"
1485	help
1486	  This option provides a kernel module that runs tests on the
1487	  on the struct ww_mutex locking API.
1488
1489	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1490	  with this test harness.
1491
1492	  Say M if you want these self tests to build as a module.
1493	  Say N if you are unsure.
1494
1495config SCF_TORTURE_TEST
1496	tristate "torture tests for smp_call_function*()"
1497	depends on DEBUG_KERNEL
1498	select TORTURE_TEST
1499	help
1500	  This option provides a kernel module that runs torture tests
1501	  on the smp_call_function() family of primitives.  The kernel
1502	  module may be built after the fact on the running kernel to
1503	  be tested, if desired.
1504
1505config CSD_LOCK_WAIT_DEBUG
1506	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1507	depends on DEBUG_KERNEL
1508	depends on 64BIT
1509	default n
1510	help
1511	  This option enables debug prints when CPUs are slow to respond
1512	  to the smp_call_function*() IPI wrappers.  These debug prints
1513	  include the IPI handler function currently executing (if any)
1514	  and relevant stack traces.
1515
1516endmenu # lock debugging
1517
1518config TRACE_IRQFLAGS
1519	depends on TRACE_IRQFLAGS_SUPPORT
1520	bool
1521	help
1522	  Enables hooks to interrupt enabling and disabling for
1523	  either tracing or lock debugging.
1524
1525config TRACE_IRQFLAGS_NMI
1526	def_bool y
1527	depends on TRACE_IRQFLAGS
1528	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1529
1530config DEBUG_IRQFLAGS
1531	bool "Debug IRQ flag manipulation"
1532	help
1533	  Enables checks for potentially unsafe enabling or disabling of
1534	  interrupts, such as calling raw_local_irq_restore() when interrupts
1535	  are enabled.
1536
1537config STACKTRACE
1538	bool "Stack backtrace support"
1539	depends on STACKTRACE_SUPPORT
1540	help
1541	  This option causes the kernel to create a /proc/pid/stack for
1542	  every process, showing its current stack trace.
1543	  It is also used by various kernel debugging features that require
1544	  stack trace generation.
1545
1546config WARN_ALL_UNSEEDED_RANDOM
1547	bool "Warn for all uses of unseeded randomness"
1548	default n
1549	help
1550	  Some parts of the kernel contain bugs relating to their use of
1551	  cryptographically secure random numbers before it's actually possible
1552	  to generate those numbers securely. This setting ensures that these
1553	  flaws don't go unnoticed, by enabling a message, should this ever
1554	  occur. This will allow people with obscure setups to know when things
1555	  are going wrong, so that they might contact developers about fixing
1556	  it.
1557
1558	  Unfortunately, on some models of some architectures getting
1559	  a fully seeded CRNG is extremely difficult, and so this can
1560	  result in dmesg getting spammed for a surprisingly long
1561	  time.  This is really bad from a security perspective, and
1562	  so architecture maintainers really need to do what they can
1563	  to get the CRNG seeded sooner after the system is booted.
1564	  However, since users cannot do anything actionable to
1565	  address this, by default this option is disabled.
1566
1567	  Say Y here if you want to receive warnings for all uses of
1568	  unseeded randomness.  This will be of use primarily for
1569	  those developers interested in improving the security of
1570	  Linux kernels running on their architecture (or
1571	  subarchitecture).
1572
1573config DEBUG_KOBJECT
1574	bool "kobject debugging"
1575	depends on DEBUG_KERNEL
1576	help
1577	  If you say Y here, some extra kobject debugging messages will be sent
1578	  to the syslog.
1579
1580config DEBUG_KOBJECT_RELEASE
1581	bool "kobject release debugging"
1582	depends on DEBUG_OBJECTS_TIMERS
1583	help
1584	  kobjects are reference counted objects.  This means that their
1585	  last reference count put is not predictable, and the kobject can
1586	  live on past the point at which a driver decides to drop its
1587	  initial reference to the kobject gained on allocation.  An
1588	  example of this would be a struct device which has just been
1589	  unregistered.
1590
1591	  However, some buggy drivers assume that after such an operation,
1592	  the memory backing the kobject can be immediately freed.  This
1593	  goes completely against the principles of a refcounted object.
1594
1595	  If you say Y here, the kernel will delay the release of kobjects
1596	  on the last reference count to improve the visibility of this
1597	  kind of kobject release bug.
1598
1599config HAVE_DEBUG_BUGVERBOSE
1600	bool
1601
1602menu "Debug kernel data structures"
1603
1604config DEBUG_LIST
1605	bool "Debug linked list manipulation"
1606	depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
1607	help
1608	  Enable this to turn on extended checks in the linked-list
1609	  walking routines.
1610
1611	  If unsure, say N.
1612
1613config DEBUG_PLIST
1614	bool "Debug priority linked list manipulation"
1615	depends on DEBUG_KERNEL
1616	help
1617	  Enable this to turn on extended checks in the priority-ordered
1618	  linked-list (plist) walking routines.  This checks the entire
1619	  list multiple times during each manipulation.
1620
1621	  If unsure, say N.
1622
1623config DEBUG_SG
1624	bool "Debug SG table operations"
1625	depends on DEBUG_KERNEL
1626	help
1627	  Enable this to turn on checks on scatter-gather tables. This can
1628	  help find problems with drivers that do not properly initialize
1629	  their sg tables.
1630
1631	  If unsure, say N.
1632
1633config DEBUG_NOTIFIERS
1634	bool "Debug notifier call chains"
1635	depends on DEBUG_KERNEL
1636	help
1637	  Enable this to turn on sanity checking for notifier call chains.
1638	  This is most useful for kernel developers to make sure that
1639	  modules properly unregister themselves from notifier chains.
1640	  This is a relatively cheap check but if you care about maximum
1641	  performance, say N.
1642
1643config BUG_ON_DATA_CORRUPTION
1644	bool "Trigger a BUG when data corruption is detected"
1645	select DEBUG_LIST
1646	help
1647	  Select this option if the kernel should BUG when it encounters
1648	  data corruption in kernel memory structures when they get checked
1649	  for validity.
1650
1651	  If unsure, say N.
1652
1653config DEBUG_MAPLE_TREE
1654	bool "Debug maple trees"
1655	depends on DEBUG_KERNEL
1656	help
1657	  Enable maple tree debugging information and extra validations.
1658
1659	  If unsure, say N.
1660
1661endmenu
1662
1663config DEBUG_CREDENTIALS
1664	bool "Debug credential management"
1665	depends on DEBUG_KERNEL
1666	help
1667	  Enable this to turn on some debug checking for credential
1668	  management.  The additional code keeps track of the number of
1669	  pointers from task_structs to any given cred struct, and checks to
1670	  see that this number never exceeds the usage count of the cred
1671	  struct.
1672
1673	  Furthermore, if SELinux is enabled, this also checks that the
1674	  security pointer in the cred struct is never seen to be invalid.
1675
1676	  If unsure, say N.
1677
1678source "kernel/rcu/Kconfig.debug"
1679
1680config DEBUG_WQ_FORCE_RR_CPU
1681	bool "Force round-robin CPU selection for unbound work items"
1682	depends on DEBUG_KERNEL
1683	default n
1684	help
1685	  Workqueue used to implicitly guarantee that work items queued
1686	  without explicit CPU specified are put on the local CPU.  This
1687	  guarantee is no longer true and while local CPU is still
1688	  preferred work items may be put on foreign CPUs.  Kernel
1689	  parameter "workqueue.debug_force_rr_cpu" is added to force
1690	  round-robin CPU selection to flush out usages which depend on the
1691	  now broken guarantee.  This config option enables the debug
1692	  feature by default.  When enabled, memory and cache locality will
1693	  be impacted.
1694
1695config CPU_HOTPLUG_STATE_CONTROL
1696	bool "Enable CPU hotplug state control"
1697	depends on DEBUG_KERNEL
1698	depends on HOTPLUG_CPU
1699	default n
1700	help
1701	  Allows to write steps between "offline" and "online" to the CPUs
1702	  sysfs target file so states can be stepped granular. This is a debug
1703	  option for now as the hotplug machinery cannot be stopped and
1704	  restarted at arbitrary points yet.
1705
1706	  Say N if your are unsure.
1707
1708config LATENCYTOP
1709	bool "Latency measuring infrastructure"
1710	depends on DEBUG_KERNEL
1711	depends on STACKTRACE_SUPPORT
1712	depends on PROC_FS
1713	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1714	select KALLSYMS
1715	select KALLSYMS_ALL
1716	select STACKTRACE
1717	select SCHEDSTATS
1718	help
1719	  Enable this option if you want to use the LatencyTOP tool
1720	  to find out which userspace is blocking on what kernel operations.
1721
1722config DEBUG_CGROUP_REF
1723	bool "Disable inlining of cgroup css reference count functions"
1724	depends on DEBUG_KERNEL
1725	depends on CGROUPS
1726	depends on KPROBES
1727	default n
1728	help
1729	  Force cgroup css reference count functions to not be inlined so
1730	  that they can be kprobed for debugging.
1731
1732source "kernel/trace/Kconfig"
1733
1734config PROVIDE_OHCI1394_DMA_INIT
1735	bool "Remote debugging over FireWire early on boot"
1736	depends on PCI && X86
1737	help
1738	  If you want to debug problems which hang or crash the kernel early
1739	  on boot and the crashing machine has a FireWire port, you can use
1740	  this feature to remotely access the memory of the crashed machine
1741	  over FireWire. This employs remote DMA as part of the OHCI1394
1742	  specification which is now the standard for FireWire controllers.
1743
1744	  With remote DMA, you can monitor the printk buffer remotely using
1745	  firescope and access all memory below 4GB using fireproxy from gdb.
1746	  Even controlling a kernel debugger is possible using remote DMA.
1747
1748	  Usage:
1749
1750	  If ohci1394_dma=early is used as boot parameter, it will initialize
1751	  all OHCI1394 controllers which are found in the PCI config space.
1752
1753	  As all changes to the FireWire bus such as enabling and disabling
1754	  devices cause a bus reset and thereby disable remote DMA for all
1755	  devices, be sure to have the cable plugged and FireWire enabled on
1756	  the debugging host before booting the debug target for debugging.
1757
1758	  This code (~1k) is freed after boot. By then, the firewire stack
1759	  in charge of the OHCI-1394 controllers should be used instead.
1760
1761	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1762
1763source "samples/Kconfig"
1764
1765config ARCH_HAS_DEVMEM_IS_ALLOWED
1766	bool
1767
1768config STRICT_DEVMEM
1769	bool "Filter access to /dev/mem"
1770	depends on MMU && DEVMEM
1771	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1772	default y if PPC || X86 || ARM64
1773	help
1774	  If this option is disabled, you allow userspace (root) access to all
1775	  of memory, including kernel and userspace memory. Accidental
1776	  access to this is obviously disastrous, but specific access can
1777	  be used by people debugging the kernel. Note that with PAT support
1778	  enabled, even in this case there are restrictions on /dev/mem
1779	  use due to the cache aliasing requirements.
1780
1781	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1782	  file only allows userspace access to PCI space and the BIOS code and
1783	  data regions.  This is sufficient for dosemu and X and all common
1784	  users of /dev/mem.
1785
1786	  If in doubt, say Y.
1787
1788config IO_STRICT_DEVMEM
1789	bool "Filter I/O access to /dev/mem"
1790	depends on STRICT_DEVMEM
1791	help
1792	  If this option is disabled, you allow userspace (root) access to all
1793	  io-memory regardless of whether a driver is actively using that
1794	  range.  Accidental access to this is obviously disastrous, but
1795	  specific access can be used by people debugging kernel drivers.
1796
1797	  If this option is switched on, the /dev/mem file only allows
1798	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1799	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1800	  if the driver using a given range cannot be disabled.
1801
1802	  If in doubt, say Y.
1803
1804menu "$(SRCARCH) Debugging"
1805
1806source "arch/$(SRCARCH)/Kconfig.debug"
1807
1808endmenu
1809
1810menu "Kernel Testing and Coverage"
1811
1812source "lib/kunit/Kconfig"
1813
1814config NOTIFIER_ERROR_INJECTION
1815	tristate "Notifier error injection"
1816	depends on DEBUG_KERNEL
1817	select DEBUG_FS
1818	help
1819	  This option provides the ability to inject artificial errors to
1820	  specified notifier chain callbacks. It is useful to test the error
1821	  handling of notifier call chain failures.
1822
1823	  Say N if unsure.
1824
1825config PM_NOTIFIER_ERROR_INJECT
1826	tristate "PM notifier error injection module"
1827	depends on PM && NOTIFIER_ERROR_INJECTION
1828	default m if PM_DEBUG
1829	help
1830	  This option provides the ability to inject artificial errors to
1831	  PM notifier chain callbacks.  It is controlled through debugfs
1832	  interface /sys/kernel/debug/notifier-error-inject/pm
1833
1834	  If the notifier call chain should be failed with some events
1835	  notified, write the error code to "actions/<notifier event>/error".
1836
1837	  Example: Inject PM suspend error (-12 = -ENOMEM)
1838
1839	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1840	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1841	  # echo mem > /sys/power/state
1842	  bash: echo: write error: Cannot allocate memory
1843
1844	  To compile this code as a module, choose M here: the module will
1845	  be called pm-notifier-error-inject.
1846
1847	  If unsure, say N.
1848
1849config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1850	tristate "OF reconfig notifier error injection module"
1851	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1852	help
1853	  This option provides the ability to inject artificial errors to
1854	  OF reconfig notifier chain callbacks.  It is controlled
1855	  through debugfs interface under
1856	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1857
1858	  If the notifier call chain should be failed with some events
1859	  notified, write the error code to "actions/<notifier event>/error".
1860
1861	  To compile this code as a module, choose M here: the module will
1862	  be called of-reconfig-notifier-error-inject.
1863
1864	  If unsure, say N.
1865
1866config NETDEV_NOTIFIER_ERROR_INJECT
1867	tristate "Netdev notifier error injection module"
1868	depends on NET && NOTIFIER_ERROR_INJECTION
1869	help
1870	  This option provides the ability to inject artificial errors to
1871	  netdevice notifier chain callbacks.  It is controlled through debugfs
1872	  interface /sys/kernel/debug/notifier-error-inject/netdev
1873
1874	  If the notifier call chain should be failed with some events
1875	  notified, write the error code to "actions/<notifier event>/error".
1876
1877	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1878
1879	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1880	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1881	  # ip link set eth0 mtu 1024
1882	  RTNETLINK answers: Invalid argument
1883
1884	  To compile this code as a module, choose M here: the module will
1885	  be called netdev-notifier-error-inject.
1886
1887	  If unsure, say N.
1888
1889config FUNCTION_ERROR_INJECTION
1890	bool "Fault-injections of functions"
1891	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1892	help
1893	  Add fault injections into various functions that are annotated with
1894	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1895	  value of theses functions. This is useful to test error paths of code.
1896
1897	  If unsure, say N
1898
1899config FAULT_INJECTION
1900	bool "Fault-injection framework"
1901	depends on DEBUG_KERNEL
1902	help
1903	  Provide fault-injection framework.
1904	  For more details, see Documentation/fault-injection/.
1905
1906config FAILSLAB
1907	bool "Fault-injection capability for kmalloc"
1908	depends on FAULT_INJECTION
1909	depends on SLAB || SLUB
1910	help
1911	  Provide fault-injection capability for kmalloc.
1912
1913config FAIL_PAGE_ALLOC
1914	bool "Fault-injection capability for alloc_pages()"
1915	depends on FAULT_INJECTION
1916	help
1917	  Provide fault-injection capability for alloc_pages().
1918
1919config FAULT_INJECTION_USERCOPY
1920	bool "Fault injection capability for usercopy functions"
1921	depends on FAULT_INJECTION
1922	help
1923	  Provides fault-injection capability to inject failures
1924	  in usercopy functions (copy_from_user(), get_user(), ...).
1925
1926config FAIL_MAKE_REQUEST
1927	bool "Fault-injection capability for disk IO"
1928	depends on FAULT_INJECTION && BLOCK
1929	help
1930	  Provide fault-injection capability for disk IO.
1931
1932config FAIL_IO_TIMEOUT
1933	bool "Fault-injection capability for faking disk interrupts"
1934	depends on FAULT_INJECTION && BLOCK
1935	help
1936	  Provide fault-injection capability on end IO handling. This
1937	  will make the block layer "forget" an interrupt as configured,
1938	  thus exercising the error handling.
1939
1940	  Only works with drivers that use the generic timeout handling,
1941	  for others it won't do anything.
1942
1943config FAIL_FUTEX
1944	bool "Fault-injection capability for futexes"
1945	select DEBUG_FS
1946	depends on FAULT_INJECTION && FUTEX
1947	help
1948	  Provide fault-injection capability for futexes.
1949
1950config FAULT_INJECTION_DEBUG_FS
1951	bool "Debugfs entries for fault-injection capabilities"
1952	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1953	help
1954	  Enable configuration of fault-injection capabilities via debugfs.
1955
1956config FAIL_FUNCTION
1957	bool "Fault-injection capability for functions"
1958	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
1959	help
1960	  Provide function-based fault-injection capability.
1961	  This will allow you to override a specific function with a return
1962	  with given return value. As a result, function caller will see
1963	  an error value and have to handle it. This is useful to test the
1964	  error handling in various subsystems.
1965
1966config FAIL_MMC_REQUEST
1967	bool "Fault-injection capability for MMC IO"
1968	depends on FAULT_INJECTION_DEBUG_FS && MMC
1969	help
1970	  Provide fault-injection capability for MMC IO.
1971	  This will make the mmc core return data errors. This is
1972	  useful to test the error handling in the mmc block device
1973	  and to test how the mmc host driver handles retries from
1974	  the block device.
1975
1976config FAIL_SUNRPC
1977	bool "Fault-injection capability for SunRPC"
1978	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
1979	help
1980	  Provide fault-injection capability for SunRPC and
1981	  its consumers.
1982
1983config FAULT_INJECTION_STACKTRACE_FILTER
1984	bool "stacktrace filter for fault-injection capabilities"
1985	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1986	select STACKTRACE
1987	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1988	help
1989	  Provide stacktrace filter for fault-injection capabilities
1990
1991config ARCH_HAS_KCOV
1992	bool
1993	help
1994	  An architecture should select this when it can successfully
1995	  build and run with CONFIG_KCOV. This typically requires
1996	  disabling instrumentation for some early boot code.
1997
1998config CC_HAS_SANCOV_TRACE_PC
1999	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2000
2001
2002config KCOV
2003	bool "Code coverage for fuzzing"
2004	depends on ARCH_HAS_KCOV
2005	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2006	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2007		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2008	select DEBUG_FS
2009	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2010	select OBJTOOL if HAVE_NOINSTR_HACK
2011	help
2012	  KCOV exposes kernel code coverage information in a form suitable
2013	  for coverage-guided fuzzing (randomized testing).
2014
2015	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
2016	  different machines and across reboots. If you need stable PC values,
2017	  disable RANDOMIZE_BASE.
2018
2019	  For more details, see Documentation/dev-tools/kcov.rst.
2020
2021config KCOV_ENABLE_COMPARISONS
2022	bool "Enable comparison operands collection by KCOV"
2023	depends on KCOV
2024	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2025	help
2026	  KCOV also exposes operands of every comparison in the instrumented
2027	  code along with operand sizes and PCs of the comparison instructions.
2028	  These operands can be used by fuzzing engines to improve the quality
2029	  of fuzzing coverage.
2030
2031config KCOV_INSTRUMENT_ALL
2032	bool "Instrument all code by default"
2033	depends on KCOV
2034	default y
2035	help
2036	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2037	  then you will want to instrument the whole kernel and you should
2038	  say y here. If you are doing more targeted fuzzing (like e.g.
2039	  filesystem fuzzing with AFL) then you will want to enable coverage
2040	  for more specific subsets of files, and should say n here.
2041
2042config KCOV_IRQ_AREA_SIZE
2043	hex "Size of interrupt coverage collection area in words"
2044	depends on KCOV
2045	default 0x40000
2046	help
2047	  KCOV uses preallocated per-cpu areas to collect coverage from
2048	  soft interrupts. This specifies the size of those areas in the
2049	  number of unsigned long words.
2050
2051menuconfig RUNTIME_TESTING_MENU
2052	bool "Runtime Testing"
2053	def_bool y
2054
2055if RUNTIME_TESTING_MENU
2056
2057config LKDTM
2058	tristate "Linux Kernel Dump Test Tool Module"
2059	depends on DEBUG_FS
2060	help
2061	This module enables testing of the different dumping mechanisms by
2062	inducing system failures at predefined crash points.
2063	If you don't need it: say N
2064	Choose M here to compile this code as a module. The module will be
2065	called lkdtm.
2066
2067	Documentation on how to use the module can be found in
2068	Documentation/fault-injection/provoke-crashes.rst
2069
2070config CPUMASK_KUNIT_TEST
2071	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2072	depends on KUNIT
2073	default KUNIT_ALL_TESTS
2074	help
2075	  Enable to turn on cpumask tests, running at boot or module load time.
2076
2077	  For more information on KUnit and unit tests in general, please refer
2078	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2079
2080	  If unsure, say N.
2081
2082config TEST_LIST_SORT
2083	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2084	depends on KUNIT
2085	default KUNIT_ALL_TESTS
2086	help
2087	  Enable this to turn on 'list_sort()' function test. This test is
2088	  executed only once during system boot (so affects only boot time),
2089	  or at module load time.
2090
2091	  If unsure, say N.
2092
2093config TEST_MIN_HEAP
2094	tristate "Min heap test"
2095	depends on DEBUG_KERNEL || m
2096	help
2097	  Enable this to turn on min heap function tests. This test is
2098	  executed only once during system boot (so affects only boot time),
2099	  or at module load time.
2100
2101	  If unsure, say N.
2102
2103config TEST_SORT
2104	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2105	depends on KUNIT
2106	default KUNIT_ALL_TESTS
2107	help
2108	  This option enables the self-test function of 'sort()' at boot,
2109	  or at module load time.
2110
2111	  If unsure, say N.
2112
2113config TEST_DIV64
2114	tristate "64bit/32bit division and modulo test"
2115	depends on DEBUG_KERNEL || m
2116	help
2117	  Enable this to turn on 'do_div()' function test. This test is
2118	  executed only once during system boot (so affects only boot time),
2119	  or at module load time.
2120
2121	  If unsure, say N.
2122
2123config KPROBES_SANITY_TEST
2124	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2125	depends on DEBUG_KERNEL
2126	depends on KPROBES
2127	depends on KUNIT
2128	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2129	default KUNIT_ALL_TESTS
2130	help
2131	  This option provides for testing basic kprobes functionality on
2132	  boot. Samples of kprobe and kretprobe are inserted and
2133	  verified for functionality.
2134
2135	  Say N if you are unsure.
2136
2137config FPROBE_SANITY_TEST
2138	bool "Self test for fprobe"
2139	depends on DEBUG_KERNEL
2140	depends on FPROBE
2141	depends on KUNIT=y
2142	help
2143	  This option will enable testing the fprobe when the system boot.
2144	  A series of tests are made to verify that the fprobe is functioning
2145	  properly.
2146
2147	  Say N if you are unsure.
2148
2149config BACKTRACE_SELF_TEST
2150	tristate "Self test for the backtrace code"
2151	depends on DEBUG_KERNEL
2152	help
2153	  This option provides a kernel module that can be used to test
2154	  the kernel stack backtrace code. This option is not useful
2155	  for distributions or general kernels, but only for kernel
2156	  developers working on architecture code.
2157
2158	  Note that if you want to also test saved backtraces, you will
2159	  have to enable STACKTRACE as well.
2160
2161	  Say N if you are unsure.
2162
2163config TEST_REF_TRACKER
2164	tristate "Self test for reference tracker"
2165	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2166	select REF_TRACKER
2167	help
2168	  This option provides a kernel module performing tests
2169	  using reference tracker infrastructure.
2170
2171	  Say N if you are unsure.
2172
2173config RBTREE_TEST
2174	tristate "Red-Black tree test"
2175	depends on DEBUG_KERNEL
2176	help
2177	  A benchmark measuring the performance of the rbtree library.
2178	  Also includes rbtree invariant checks.
2179
2180config REED_SOLOMON_TEST
2181	tristate "Reed-Solomon library test"
2182	depends on DEBUG_KERNEL || m
2183	select REED_SOLOMON
2184	select REED_SOLOMON_ENC16
2185	select REED_SOLOMON_DEC16
2186	help
2187	  This option enables the self-test function of rslib at boot,
2188	  or at module load time.
2189
2190	  If unsure, say N.
2191
2192config INTERVAL_TREE_TEST
2193	tristate "Interval tree test"
2194	depends on DEBUG_KERNEL
2195	select INTERVAL_TREE
2196	help
2197	  A benchmark measuring the performance of the interval tree library
2198
2199config PERCPU_TEST
2200	tristate "Per cpu operations test"
2201	depends on m && DEBUG_KERNEL
2202	help
2203	  Enable this option to build test module which validates per-cpu
2204	  operations.
2205
2206	  If unsure, say N.
2207
2208config ATOMIC64_SELFTEST
2209	tristate "Perform an atomic64_t self-test"
2210	help
2211	  Enable this option to test the atomic64_t functions at boot or
2212	  at module load time.
2213
2214	  If unsure, say N.
2215
2216config ASYNC_RAID6_TEST
2217	tristate "Self test for hardware accelerated raid6 recovery"
2218	depends on ASYNC_RAID6_RECOV
2219	select ASYNC_MEMCPY
2220	help
2221	  This is a one-shot self test that permutes through the
2222	  recovery of all the possible two disk failure scenarios for a
2223	  N-disk array.  Recovery is performed with the asynchronous
2224	  raid6 recovery routines, and will optionally use an offload
2225	  engine if one is available.
2226
2227	  If unsure, say N.
2228
2229config TEST_HEXDUMP
2230	tristate "Test functions located in the hexdump module at runtime"
2231
2232config STRING_SELFTEST
2233	tristate "Test string functions at runtime"
2234
2235config TEST_STRING_HELPERS
2236	tristate "Test functions located in the string_helpers module at runtime"
2237
2238config TEST_KSTRTOX
2239	tristate "Test kstrto*() family of functions at runtime"
2240
2241config TEST_PRINTF
2242	tristate "Test printf() family of functions at runtime"
2243
2244config TEST_SCANF
2245	tristate "Test scanf() family of functions at runtime"
2246
2247config TEST_BITMAP
2248	tristate "Test bitmap_*() family of functions at runtime"
2249	help
2250	  Enable this option to test the bitmap functions at boot.
2251
2252	  If unsure, say N.
2253
2254config TEST_UUID
2255	tristate "Test functions located in the uuid module at runtime"
2256
2257config TEST_XARRAY
2258	tristate "Test the XArray code at runtime"
2259
2260config TEST_MAPLE_TREE
2261	depends on DEBUG_KERNEL
2262	select DEBUG_MAPLE_TREE
2263	tristate "Test the Maple Tree code at runtime"
2264
2265config TEST_RHASHTABLE
2266	tristate "Perform selftest on resizable hash table"
2267	help
2268	  Enable this option to test the rhashtable functions at boot.
2269
2270	  If unsure, say N.
2271
2272config TEST_IDA
2273	tristate "Perform selftest on IDA functions"
2274
2275config TEST_PARMAN
2276	tristate "Perform selftest on priority array manager"
2277	depends on PARMAN
2278	help
2279	  Enable this option to test priority array manager on boot
2280	  (or module load).
2281
2282	  If unsure, say N.
2283
2284config TEST_IRQ_TIMINGS
2285	bool "IRQ timings selftest"
2286	depends on IRQ_TIMINGS
2287	help
2288	  Enable this option to test the irq timings code on boot.
2289
2290	  If unsure, say N.
2291
2292config TEST_LKM
2293	tristate "Test module loading with 'hello world' module"
2294	depends on m
2295	help
2296	  This builds the "test_module" module that emits "Hello, world"
2297	  on printk when loaded. It is designed to be used for basic
2298	  evaluation of the module loading subsystem (for example when
2299	  validating module verification). It lacks any extra dependencies,
2300	  and will not normally be loaded by the system unless explicitly
2301	  requested by name.
2302
2303	  If unsure, say N.
2304
2305config TEST_BITOPS
2306	tristate "Test module for compilation of bitops operations"
2307	depends on m
2308	help
2309	  This builds the "test_bitops" module that is much like the
2310	  TEST_LKM module except that it does a basic exercise of the
2311	  set/clear_bit macros and get_count_order/long to make sure there are
2312	  no compiler warnings from C=1 sparse checker or -Wextra
2313	  compilations. It has no dependencies and doesn't run or load unless
2314	  explicitly requested by name.  for example: modprobe test_bitops.
2315
2316	  If unsure, say N.
2317
2318config TEST_VMALLOC
2319	tristate "Test module for stress/performance analysis of vmalloc allocator"
2320	default n
2321       depends on MMU
2322	depends on m
2323	help
2324	  This builds the "test_vmalloc" module that should be used for
2325	  stress and performance analysis. So, any new change for vmalloc
2326	  subsystem can be evaluated from performance and stability point
2327	  of view.
2328
2329	  If unsure, say N.
2330
2331config TEST_USER_COPY
2332	tristate "Test user/kernel boundary protections"
2333	depends on m
2334	help
2335	  This builds the "test_user_copy" module that runs sanity checks
2336	  on the copy_to/from_user infrastructure, making sure basic
2337	  user/kernel boundary testing is working. If it fails to load,
2338	  a regression has been detected in the user/kernel memory boundary
2339	  protections.
2340
2341	  If unsure, say N.
2342
2343config TEST_BPF
2344	tristate "Test BPF filter functionality"
2345	depends on m && NET
2346	help
2347	  This builds the "test_bpf" module that runs various test vectors
2348	  against the BPF interpreter or BPF JIT compiler depending on the
2349	  current setting. This is in particular useful for BPF JIT compiler
2350	  development, but also to run regression tests against changes in
2351	  the interpreter code. It also enables test stubs for eBPF maps and
2352	  verifier used by user space verifier testsuite.
2353
2354	  If unsure, say N.
2355
2356config TEST_BLACKHOLE_DEV
2357	tristate "Test blackhole netdev functionality"
2358	depends on m && NET
2359	help
2360	  This builds the "test_blackhole_dev" module that validates the
2361	  data path through this blackhole netdev.
2362
2363	  If unsure, say N.
2364
2365config FIND_BIT_BENCHMARK
2366	tristate "Test find_bit functions"
2367	help
2368	  This builds the "test_find_bit" module that measure find_*_bit()
2369	  functions performance.
2370
2371	  If unsure, say N.
2372
2373config TEST_FIRMWARE
2374	tristate "Test firmware loading via userspace interface"
2375	depends on FW_LOADER
2376	help
2377	  This builds the "test_firmware" module that creates a userspace
2378	  interface for testing firmware loading. This can be used to
2379	  control the triggering of firmware loading without needing an
2380	  actual firmware-using device. The contents can be rechecked by
2381	  userspace.
2382
2383	  If unsure, say N.
2384
2385config TEST_SYSCTL
2386	tristate "sysctl test driver"
2387	depends on PROC_SYSCTL
2388	help
2389	  This builds the "test_sysctl" module. This driver enables to test the
2390	  proc sysctl interfaces available to drivers safely without affecting
2391	  production knobs which might alter system functionality.
2392
2393	  If unsure, say N.
2394
2395config BITFIELD_KUNIT
2396	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2397	depends on KUNIT
2398	default KUNIT_ALL_TESTS
2399	help
2400	  Enable this option to test the bitfield functions at boot.
2401
2402	  KUnit tests run during boot and output the results to the debug log
2403	  in TAP format (http://testanything.org/). Only useful for kernel devs
2404	  running the KUnit test harness, and not intended for inclusion into a
2405	  production build.
2406
2407	  For more information on KUnit and unit tests in general please refer
2408	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2409
2410	  If unsure, say N.
2411
2412config HASH_KUNIT_TEST
2413	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2414	depends on KUNIT
2415	default KUNIT_ALL_TESTS
2416	help
2417	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2418	  integer (<linux/hash.h>) hash functions on boot.
2419
2420	  KUnit tests run during boot and output the results to the debug log
2421	  in TAP format (https://testanything.org/). Only useful for kernel devs
2422	  running the KUnit test harness, and not intended for inclusion into a
2423	  production build.
2424
2425	  For more information on KUnit and unit tests in general please refer
2426	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2427
2428	  This is intended to help people writing architecture-specific
2429	  optimized versions. If unsure, say N.
2430
2431config RESOURCE_KUNIT_TEST
2432	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2433	depends on KUNIT
2434	default KUNIT_ALL_TESTS
2435	help
2436	  This builds the resource API unit test.
2437	  Tests the logic of API provided by resource.c and ioport.h.
2438	  For more information on KUnit and unit tests in general please refer
2439	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2440
2441	  If unsure, say N.
2442
2443config SYSCTL_KUNIT_TEST
2444	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2445	depends on KUNIT
2446	default KUNIT_ALL_TESTS
2447	help
2448	  This builds the proc sysctl unit test, which runs on boot.
2449	  Tests the API contract and implementation correctness of sysctl.
2450	  For more information on KUnit and unit tests in general please refer
2451	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2452
2453	  If unsure, say N.
2454
2455config LIST_KUNIT_TEST
2456	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2457	depends on KUNIT
2458	default KUNIT_ALL_TESTS
2459	help
2460	  This builds the linked list KUnit test suite.
2461	  It tests that the API and basic functionality of the list_head type
2462	  and associated macros.
2463
2464	  KUnit tests run during boot and output the results to the debug log
2465	  in TAP format (https://testanything.org/). Only useful for kernel devs
2466	  running the KUnit test harness, and not intended for inclusion into a
2467	  production build.
2468
2469	  For more information on KUnit and unit tests in general please refer
2470	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2471
2472	  If unsure, say N.
2473
2474config LINEAR_RANGES_TEST
2475	tristate "KUnit test for linear_ranges"
2476	depends on KUNIT
2477	select LINEAR_RANGES
2478	help
2479	  This builds the linear_ranges unit test, which runs on boot.
2480	  Tests the linear_ranges logic correctness.
2481	  For more information on KUnit and unit tests in general please refer
2482	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2483
2484	  If unsure, say N.
2485
2486config CMDLINE_KUNIT_TEST
2487	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2488	depends on KUNIT
2489	default KUNIT_ALL_TESTS
2490	help
2491	  This builds the cmdline API unit test.
2492	  Tests the logic of API provided by cmdline.c.
2493	  For more information on KUnit and unit tests in general please refer
2494	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2495
2496	  If unsure, say N.
2497
2498config BITS_TEST
2499	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2500	depends on KUNIT
2501	default KUNIT_ALL_TESTS
2502	help
2503	  This builds the bits unit test.
2504	  Tests the logic of macros defined in bits.h.
2505	  For more information on KUnit and unit tests in general please refer
2506	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2507
2508	  If unsure, say N.
2509
2510config SLUB_KUNIT_TEST
2511	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2512	depends on SLUB_DEBUG && KUNIT
2513	default KUNIT_ALL_TESTS
2514	help
2515	  This builds SLUB allocator unit test.
2516	  Tests SLUB cache debugging functionality.
2517	  For more information on KUnit and unit tests in general please refer
2518	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2519
2520	  If unsure, say N.
2521
2522config RATIONAL_KUNIT_TEST
2523	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2524	depends on KUNIT && RATIONAL
2525	default KUNIT_ALL_TESTS
2526	help
2527	  This builds the rational math unit test.
2528	  For more information on KUnit and unit tests in general please refer
2529	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2530
2531	  If unsure, say N.
2532
2533config MEMCPY_KUNIT_TEST
2534	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2535	depends on KUNIT
2536	default KUNIT_ALL_TESTS
2537	help
2538	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2539	  For more information on KUnit and unit tests in general please refer
2540	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2541
2542	  If unsure, say N.
2543
2544config IS_SIGNED_TYPE_KUNIT_TEST
2545	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2546	depends on KUNIT
2547	default KUNIT_ALL_TESTS
2548	help
2549	  Builds unit tests for the is_signed_type() macro.
2550
2551	  For more information on KUnit and unit tests in general please refer
2552	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2553
2554	  If unsure, say N.
2555
2556config OVERFLOW_KUNIT_TEST
2557	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2558	depends on KUNIT
2559	default KUNIT_ALL_TESTS
2560	help
2561	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2562	  related functions.
2563
2564	  For more information on KUnit and unit tests in general please refer
2565	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2566
2567	  If unsure, say N.
2568
2569config STACKINIT_KUNIT_TEST
2570	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2571	depends on KUNIT
2572	default KUNIT_ALL_TESTS
2573	help
2574	  Test if the kernel is zero-initializing stack variables and
2575	  padding. Coverage is controlled by compiler flags,
2576	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2577	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2578	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2579
2580config FORTIFY_KUNIT_TEST
2581	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2582	depends on KUNIT && FORTIFY_SOURCE
2583	default KUNIT_ALL_TESTS
2584	help
2585	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2586	  by the str*() and mem*() family of functions. For testing runtime
2587	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2588
2589config HW_BREAKPOINT_KUNIT_TEST
2590	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2591	depends on HAVE_HW_BREAKPOINT
2592	depends on KUNIT=y
2593	default KUNIT_ALL_TESTS
2594	help
2595	  Tests for hw_breakpoint constraints accounting.
2596
2597	  If unsure, say N.
2598
2599config STRSCPY_KUNIT_TEST
2600	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2601	depends on KUNIT
2602	default KUNIT_ALL_TESTS
2603
2604config SIPHASH_KUNIT_TEST
2605	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2606	depends on KUNIT
2607	default KUNIT_ALL_TESTS
2608	help
2609	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2610	  functions on boot (or module load).
2611
2612	  This is intended to help people writing architecture-specific
2613	  optimized versions.  If unsure, say N.
2614
2615config TEST_UDELAY
2616	tristate "udelay test driver"
2617	help
2618	  This builds the "udelay_test" module that helps to make sure
2619	  that udelay() is working properly.
2620
2621	  If unsure, say N.
2622
2623config TEST_STATIC_KEYS
2624	tristate "Test static keys"
2625	depends on m
2626	help
2627	  Test the static key interfaces.
2628
2629	  If unsure, say N.
2630
2631config TEST_DYNAMIC_DEBUG
2632	tristate "Test DYNAMIC_DEBUG"
2633	depends on DYNAMIC_DEBUG
2634	help
2635	  This module registers a tracer callback to count enabled
2636	  pr_debugs in a 'do_debugging' function, then alters their
2637	  enablements, calls the function, and compares counts.
2638
2639	  If unsure, say N.
2640
2641config TEST_KMOD
2642	tristate "kmod stress tester"
2643	depends on m
2644	depends on NETDEVICES && NET_CORE && INET # for TUN
2645	depends on BLOCK
2646	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2647	select TEST_LKM
2648	select XFS_FS
2649	select TUN
2650	select BTRFS_FS
2651	help
2652	  Test the kernel's module loading mechanism: kmod. kmod implements
2653	  support to load modules using the Linux kernel's usermode helper.
2654	  This test provides a series of tests against kmod.
2655
2656	  Although technically you can either build test_kmod as a module or
2657	  into the kernel we disallow building it into the kernel since
2658	  it stress tests request_module() and this will very likely cause
2659	  some issues by taking over precious threads available from other
2660	  module load requests, ultimately this could be fatal.
2661
2662	  To run tests run:
2663
2664	  tools/testing/selftests/kmod/kmod.sh --help
2665
2666	  If unsure, say N.
2667
2668config TEST_DEBUG_VIRTUAL
2669	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2670	depends on DEBUG_VIRTUAL
2671	help
2672	  Test the kernel's ability to detect incorrect calls to
2673	  virt_to_phys() done against the non-linear part of the
2674	  kernel's virtual address map.
2675
2676	  If unsure, say N.
2677
2678config TEST_MEMCAT_P
2679	tristate "Test memcat_p() helper function"
2680	help
2681	  Test the memcat_p() helper for correctly merging two
2682	  pointer arrays together.
2683
2684	  If unsure, say N.
2685
2686config TEST_LIVEPATCH
2687	tristate "Test livepatching"
2688	default n
2689	depends on DYNAMIC_DEBUG
2690	depends on LIVEPATCH
2691	depends on m
2692	help
2693	  Test kernel livepatching features for correctness.  The tests will
2694	  load test modules that will be livepatched in various scenarios.
2695
2696	  To run all the livepatching tests:
2697
2698	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2699
2700	  Alternatively, individual tests may be invoked:
2701
2702	  tools/testing/selftests/livepatch/test-callbacks.sh
2703	  tools/testing/selftests/livepatch/test-livepatch.sh
2704	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2705
2706	  If unsure, say N.
2707
2708config TEST_OBJAGG
2709	tristate "Perform selftest on object aggreration manager"
2710	default n
2711	depends on OBJAGG
2712	help
2713	  Enable this option to test object aggregation manager on boot
2714	  (or module load).
2715
2716config TEST_MEMINIT
2717	tristate "Test heap/page initialization"
2718	help
2719	  Test if the kernel is zero-initializing heap and page allocations.
2720	  This can be useful to test init_on_alloc and init_on_free features.
2721
2722	  If unsure, say N.
2723
2724config TEST_HMM
2725	tristate "Test HMM (Heterogeneous Memory Management)"
2726	depends on TRANSPARENT_HUGEPAGE
2727	depends on DEVICE_PRIVATE
2728	select HMM_MIRROR
2729	select MMU_NOTIFIER
2730	help
2731	  This is a pseudo device driver solely for testing HMM.
2732	  Say M here if you want to build the HMM test module.
2733	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2734
2735	  If unsure, say N.
2736
2737config TEST_FREE_PAGES
2738	tristate "Test freeing pages"
2739	help
2740	  Test that a memory leak does not occur due to a race between
2741	  freeing a block of pages and a speculative page reference.
2742	  Loading this module is safe if your kernel has the bug fixed.
2743	  If the bug is not fixed, it will leak gigabytes of memory and
2744	  probably OOM your system.
2745
2746config TEST_FPU
2747	tristate "Test floating point operations in kernel space"
2748	depends on X86 && !KCOV_INSTRUMENT_ALL
2749	help
2750	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2751	  which will trigger a sequence of floating point operations. This is used
2752	  for self-testing floating point control register setting in
2753	  kernel_fpu_begin().
2754
2755	  If unsure, say N.
2756
2757config TEST_CLOCKSOURCE_WATCHDOG
2758	tristate "Test clocksource watchdog in kernel space"
2759	depends on CLOCKSOURCE_WATCHDOG
2760	help
2761	  Enable this option to create a kernel module that will trigger
2762	  a test of the clocksource watchdog.  This module may be loaded
2763	  via modprobe or insmod in which case it will run upon being
2764	  loaded, or it may be built in, in which case it will run
2765	  shortly after boot.
2766
2767	  If unsure, say N.
2768
2769endif # RUNTIME_TESTING_MENU
2770
2771config ARCH_USE_MEMTEST
2772	bool
2773	help
2774	  An architecture should select this when it uses early_memtest()
2775	  during boot process.
2776
2777config MEMTEST
2778	bool "Memtest"
2779	depends on ARCH_USE_MEMTEST
2780	help
2781	  This option adds a kernel parameter 'memtest', which allows memtest
2782	  to be set and executed.
2783	        memtest=0, mean disabled; -- default
2784	        memtest=1, mean do 1 test pattern;
2785	        ...
2786	        memtest=17, mean do 17 test patterns.
2787	  If you are unsure how to answer this question, answer N.
2788
2789
2790
2791config HYPERV_TESTING
2792	bool "Microsoft Hyper-V driver testing"
2793	default n
2794	depends on HYPERV && DEBUG_FS
2795	help
2796	  Select this option to enable Hyper-V vmbus testing.
2797
2798endmenu # "Kernel Testing and Coverage"
2799
2800menu "Rust hacking"
2801
2802config RUST_DEBUG_ASSERTIONS
2803	bool "Debug assertions"
2804	depends on RUST
2805	help
2806	  Enables rustc's `-Cdebug-assertions` codegen option.
2807
2808	  This flag lets you turn `cfg(debug_assertions)` conditional
2809	  compilation on or off. This can be used to enable extra debugging
2810	  code in development but not in production. For example, it controls
2811	  the behavior of the standard library's `debug_assert!` macro.
2812
2813	  Note that this will apply to all Rust code, including `core`.
2814
2815	  If unsure, say N.
2816
2817config RUST_OVERFLOW_CHECKS
2818	bool "Overflow checks"
2819	default y
2820	depends on RUST
2821	help
2822	  Enables rustc's `-Coverflow-checks` codegen option.
2823
2824	  This flag allows you to control the behavior of runtime integer
2825	  overflow. When overflow-checks are enabled, a Rust panic will occur
2826	  on overflow.
2827
2828	  Note that this will apply to all Rust code, including `core`.
2829
2830	  If unsure, say Y.
2831
2832config RUST_BUILD_ASSERT_ALLOW
2833	bool "Allow unoptimized build-time assertions"
2834	depends on RUST
2835	help
2836	  Controls how are `build_error!` and `build_assert!` handled during build.
2837
2838	  If calls to them exist in the binary, it may indicate a violated invariant
2839	  or that the optimizer failed to verify the invariant during compilation.
2840
2841	  This should not happen, thus by default the build is aborted. However,
2842	  as an escape hatch, you can choose Y here to ignore them during build
2843	  and let the check be carried at runtime (with `panic!` being called if
2844	  the check fails).
2845
2846	  If unsure, say N.
2847
2848endmenu # "Rust"
2849
2850source "Documentation/Kconfig"
2851
2852endmenu # Kernel hacking
2853