xref: /linux-6.15/lib/Kconfig.debug (revision 4525462d)
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 generates .uleb128 with label differences for DWARF v5, a feature that
235# older binutils ports do not support when utilizing RISC-V style linker
236# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
237config AS_HAS_NON_CONST_ULEB128
238	def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
239
240choice
241	prompt "Debug information"
242	depends on DEBUG_KERNEL
243	help
244	  Selecting something other than "None" results in a kernel image
245	  that will include debugging info resulting in a larger kernel image.
246	  This adds debug symbols to the kernel and modules (gcc -g), and
247	  is needed if you intend to use kernel crashdump or binary object
248	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
249
250	  Choose which version of DWARF debug info to emit. If unsure,
251	  select "Toolchain default".
252
253config DEBUG_INFO_NONE
254	bool "Disable debug information"
255	help
256	  Do not build the kernel with debugging information, which will
257	  result in a faster and smaller build.
258
259config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
260	bool "Rely on the toolchain's implicit default DWARF version"
261	select DEBUG_INFO
262	depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
263	help
264	  The implicit default version of DWARF debug info produced by a
265	  toolchain changes over time.
266
267	  This can break consumers of the debug info that haven't upgraded to
268	  support newer revisions, and prevent testing newer versions, but
269	  those should be less common scenarios.
270
271config DEBUG_INFO_DWARF4
272	bool "Generate DWARF Version 4 debuginfo"
273	select DEBUG_INFO
274	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
275	help
276	  Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
277	  if using clang without clang's integrated assembler, and gdb 7.0+.
278
279	  If you have consumers of DWARF debug info that are not ready for
280	  newer revisions of DWARF, you may wish to choose this or have your
281	  config select this.
282
283config DEBUG_INFO_DWARF5
284	bool "Generate DWARF Version 5 debuginfo"
285	select DEBUG_INFO
286	depends on !ARCH_HAS_BROKEN_DWARF5
287	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
288	help
289	  Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
290	  5.0+ accepts the -gdwarf-5 flag but only had partial support for some
291	  draft features until 7.0), and gdb 8.0+.
292
293	  Changes to the structure of debug info in Version 5 allow for around
294	  15-18% savings in resulting image and debug info section sizes as
295	  compared to DWARF Version 4. DWARF Version 5 standardizes previous
296	  extensions such as accelerators for symbol indexing and the format
297	  for fission (.dwo/.dwp) files. Users may not want to select this
298	  config if they rely on tooling that has not yet been updated to
299	  support DWARF Version 5.
300
301endchoice # "Debug information"
302
303if DEBUG_INFO
304
305config DEBUG_INFO_REDUCED
306	bool "Reduce debugging information"
307	help
308	  If you say Y here gcc is instructed to generate less debugging
309	  information for structure types. This means that tools that
310	  need full debugging information (like kgdb or systemtap) won't
311	  be happy. But if you merely need debugging information to
312	  resolve line numbers there is no loss. Advantage is that
313	  build directory object sizes shrink dramatically over a full
314	  DEBUG_INFO build and compile times are reduced too.
315	  Only works with newer gcc versions.
316
317choice
318	prompt "Compressed Debug information"
319	help
320	  Compress the resulting debug info. Results in smaller debug info sections,
321	  but requires that consumers are able to decompress the results.
322
323	  If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
324
325config DEBUG_INFO_COMPRESSED_NONE
326	bool "Don't compress debug information"
327	help
328	  Don't compress debug info sections.
329
330config DEBUG_INFO_COMPRESSED_ZLIB
331	bool "Compress debugging information with zlib"
332	depends on $(cc-option,-gz=zlib)
333	depends on $(ld-option,--compress-debug-sections=zlib)
334	help
335	  Compress the debug information using zlib.  Requires GCC 5.0+ or Clang
336	  5.0+, binutils 2.26+, and zlib.
337
338	  Users of dpkg-deb via scripts/package/builddeb may find an increase in
339	  size of their debug .deb packages with this config set, due to the
340	  debug info being compressed with zlib, then the object files being
341	  recompressed with a different compression scheme. But this is still
342	  preferable to setting $KDEB_COMPRESS to "none" which would be even
343	  larger.
344
345config DEBUG_INFO_COMPRESSED_ZSTD
346	bool "Compress debugging information with zstd"
347	depends on $(cc-option,-gz=zstd)
348	depends on $(ld-option,--compress-debug-sections=zstd)
349	help
350	  Compress the debug information using zstd.  This may provide better
351	  compression than zlib, for about the same time costs, but requires newer
352	  toolchain support.  Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
353	  zstd.
354
355endchoice # "Compressed Debug information"
356
357config DEBUG_INFO_SPLIT
358	bool "Produce split debuginfo in .dwo files"
359	depends on $(cc-option,-gsplit-dwarf)
360	# RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
361	# prior to 12.x:
362	# https://github.com/llvm/llvm-project/issues/56642
363	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
364	depends on !RISCV || GCC_VERSION >= 120000
365	help
366	  Generate debug info into separate .dwo files. This significantly
367	  reduces the build directory size for builds with DEBUG_INFO,
368	  because it stores the information only once on disk in .dwo
369	  files instead of multiple times in object files and executables.
370	  In addition the debug information is also compressed.
371
372	  Requires recent gcc (4.7+) and recent gdb/binutils.
373	  Any tool that packages or reads debug information would need
374	  to know about the .dwo files and include them.
375	  Incompatible with older versions of ccache.
376
377config DEBUG_INFO_BTF
378	bool "Generate BTF typeinfo"
379	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
380	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
381	depends on BPF_SYSCALL
382	depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
383	help
384	  Generate deduplicated BTF type information from DWARF debug info.
385	  Turning this on expects presence of pahole tool, which will convert
386	  DWARF type info into equivalent deduplicated BTF type info.
387
388config PAHOLE_HAS_SPLIT_BTF
389	def_bool PAHOLE_VERSION >= 119
390
391config PAHOLE_HAS_BTF_TAG
392	def_bool PAHOLE_VERSION >= 123
393	depends on CC_IS_CLANG
394	help
395	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
396	  btf_decl_tag) or not. Currently only clang compiler implements
397	  these attributes, so make the config depend on CC_IS_CLANG.
398
399config PAHOLE_HAS_LANG_EXCLUDE
400	def_bool PAHOLE_VERSION >= 124
401	help
402	  Support for the --lang_exclude flag which makes pahole exclude
403	  compilation units from the supplied language. Used in Kbuild to
404	  omit Rust CUs which are not supported in version 1.24 of pahole,
405	  otherwise it would emit malformed kernel and module binaries when
406	  using DEBUG_INFO_BTF_MODULES.
407
408config DEBUG_INFO_BTF_MODULES
409	def_bool y
410	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
411	help
412	  Generate compact split BTF type information for kernel modules.
413
414config MODULE_ALLOW_BTF_MISMATCH
415	bool "Allow loading modules with non-matching BTF type info"
416	depends on DEBUG_INFO_BTF_MODULES
417	help
418	  For modules whose split BTF does not match vmlinux, load without
419	  BTF rather than refusing to load. The default behavior with
420	  module BTF enabled is to reject modules with such mismatches;
421	  this option will still load module BTF where possible but ignore
422	  it when a mismatch is found.
423
424config GDB_SCRIPTS
425	bool "Provide GDB scripts for kernel debugging"
426	help
427	  This creates the required links to GDB helper scripts in the
428	  build directory. If you load vmlinux into gdb, the helper
429	  scripts will be automatically imported by gdb as well, and
430	  additional functions are available to analyze a Linux kernel
431	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
432	  for further details.
433
434endif # DEBUG_INFO
435
436config FRAME_WARN
437	int "Warn for stack frames larger than"
438	range 0 8192
439	default 0 if KMSAN
440	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
441	default 2048 if PARISC
442	default 1536 if (!64BIT && XTENSA)
443	default 1280 if KASAN && !64BIT
444	default 1024 if !64BIT
445	default 2048 if 64BIT
446	help
447	  Tell the compiler to warn at build time for stack frames larger than this.
448	  Setting this too low will cause a lot of warnings.
449	  Setting it to 0 disables the warning.
450
451config STRIP_ASM_SYMS
452	bool "Strip assembler-generated symbols during link"
453	default n
454	help
455	  Strip internal assembler-generated symbols during a link (symbols
456	  that look like '.Lxxx') so they don't pollute the output of
457	  get_wchan() and suchlike.
458
459config READABLE_ASM
460	bool "Generate readable assembler code"
461	depends on DEBUG_KERNEL
462	depends on CC_IS_GCC
463	help
464	  Disable some compiler optimizations that tend to generate human unreadable
465	  assembler output. This may make the kernel slightly slower, but it helps
466	  to keep kernel developers who have to stare a lot at assembler listings
467	  sane.
468
469config HEADERS_INSTALL
470	bool "Install uapi headers to usr/include"
471	depends on !UML
472	help
473	  This option will install uapi headers (headers exported to user-space)
474	  into the usr/include directory for use during the kernel build.
475	  This is unneeded for building the kernel itself, but needed for some
476	  user-space program samples. It is also needed by some features such
477	  as uapi header sanity checks.
478
479config DEBUG_SECTION_MISMATCH
480	bool "Enable full Section mismatch analysis"
481	depends on CC_IS_GCC
482	help
483	  The section mismatch analysis checks if there are illegal
484	  references from one section to another section.
485	  During linktime or runtime, some sections are dropped;
486	  any use of code/data previously in these sections would
487	  most likely result in an oops.
488	  In the code, functions and variables are annotated with
489	  __init,, etc. (see the full list in include/linux/init.h),
490	  which results in the code/data being placed in specific sections.
491	  The section mismatch analysis is always performed after a full
492	  kernel build, and enabling this option causes the following
493	  additional step to occur:
494	  - Add the option -fno-inline-functions-called-once to gcc commands.
495	    When inlining a function annotated with __init in a non-init
496	    function, we would lose the section information and thus
497	    the analysis would not catch the illegal reference.
498	    This option tells gcc to inline less (but it does result in
499	    a larger kernel).
500
501config SECTION_MISMATCH_WARN_ONLY
502	bool "Make section mismatch errors non-fatal"
503	default y
504	help
505	  If you say N here, the build process will fail if there are any
506	  section mismatch, instead of just throwing warnings.
507
508	  If unsure, say Y.
509
510config DEBUG_FORCE_FUNCTION_ALIGN_64B
511	bool "Force all function address 64B aligned"
512	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
513	select FUNCTION_ALIGNMENT_64B
514	help
515	  There are cases that a commit from one domain changes the function
516	  address alignment of other domains, and cause magic performance
517	  bump (regression or improvement). Enable this option will help to
518	  verify if the bump is caused by function alignment changes, while
519	  it will slightly increase the kernel size and affect icache usage.
520
521	  It is mainly for debug and performance tuning use.
522
523#
524# Select this config option from the architecture Kconfig, if it
525# is preferred to always offer frame pointers as a config
526# option on the architecture (regardless of KERNEL_DEBUG):
527#
528config ARCH_WANT_FRAME_POINTERS
529	bool
530
531config FRAME_POINTER
532	bool "Compile the kernel with frame pointers"
533	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
534	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
535	help
536	  If you say Y here the resulting kernel image will be slightly
537	  larger and slower, but it gives very useful debugging information
538	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
539
540config OBJTOOL
541	bool
542
543config STACK_VALIDATION
544	bool "Compile-time stack metadata validation"
545	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
546	select OBJTOOL
547	default n
548	help
549	  Validate frame pointer rules at compile-time.  This helps ensure that
550	  runtime stack traces are more reliable.
551
552	  For more information, see
553	  tools/objtool/Documentation/objtool.txt.
554
555config NOINSTR_VALIDATION
556	bool
557	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
558	select OBJTOOL
559	default y
560
561config VMLINUX_MAP
562	bool "Generate vmlinux.map file when linking"
563	depends on EXPERT
564	help
565	  Selecting this option will pass "-Map=vmlinux.map" to ld
566	  when linking vmlinux. That file can be useful for verifying
567	  and debugging magic section games, and for seeing which
568	  pieces of code get eliminated with
569	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
570
571config DEBUG_FORCE_WEAK_PER_CPU
572	bool "Force weak per-cpu definitions"
573	depends on DEBUG_KERNEL
574	help
575	  s390 and alpha require percpu variables in modules to be
576	  defined weak to work around addressing range issue which
577	  puts the following two restrictions on percpu variable
578	  definitions.
579
580	  1. percpu symbols must be unique whether static or not
581	  2. percpu variables can't be defined inside a function
582
583	  To ensure that generic code follows the above rules, this
584	  option forces all percpu variables to be defined as weak.
585
586endmenu # "Compiler options"
587
588menu "Generic Kernel Debugging Instruments"
589
590config MAGIC_SYSRQ
591	bool "Magic SysRq key"
592	depends on !UML
593	help
594	  If you say Y here, you will have some control over the system even
595	  if the system crashes for example during kernel debugging (e.g., you
596	  will be able to flush the buffer cache to disk, reboot the system
597	  immediately or dump some status information). This is accomplished
598	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
599	  also works on a serial console (on PC hardware at least), if you
600	  send a BREAK and then within 5 seconds a command keypress. The
601	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
602	  Don't say Y unless you really know what this hack does.
603
604config MAGIC_SYSRQ_DEFAULT_ENABLE
605	hex "Enable magic SysRq key functions by default"
606	depends on MAGIC_SYSRQ
607	default 0x1
608	help
609	  Specifies which SysRq key functions are enabled by default.
610	  This may be set to 1 or 0 to enable or disable them all, or
611	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
612
613config MAGIC_SYSRQ_SERIAL
614	bool "Enable magic SysRq key over serial"
615	depends on MAGIC_SYSRQ
616	default y
617	help
618	  Many embedded boards have a disconnected TTL level serial which can
619	  generate some garbage that can lead to spurious false sysrq detects.
620	  This option allows you to decide whether you want to enable the
621	  magic SysRq key.
622
623config MAGIC_SYSRQ_SERIAL_SEQUENCE
624	string "Char sequence that enables magic SysRq over serial"
625	depends on MAGIC_SYSRQ_SERIAL
626	default ""
627	help
628	  Specifies a sequence of characters that can follow BREAK to enable
629	  SysRq on a serial console.
630
631	  If unsure, leave an empty string and the option will not be enabled.
632
633config DEBUG_FS
634	bool "Debug Filesystem"
635	help
636	  debugfs is a virtual file system that kernel developers use to put
637	  debugging files into.  Enable this option to be able to read and
638	  write to these files.
639
640	  For detailed documentation on the debugfs API, see
641	  Documentation/filesystems/.
642
643	  If unsure, say N.
644
645choice
646	prompt "Debugfs default access"
647	depends on DEBUG_FS
648	default DEBUG_FS_ALLOW_ALL
649	help
650	  This selects the default access restrictions for debugfs.
651	  It can be overridden with kernel command line option
652	  debugfs=[on,no-mount,off]. The restrictions apply for API access
653	  and filesystem registration.
654
655config DEBUG_FS_ALLOW_ALL
656	bool "Access normal"
657	help
658	  No restrictions apply. Both API and filesystem registration
659	  is on. This is the normal default operation.
660
661config DEBUG_FS_DISALLOW_MOUNT
662	bool "Do not register debugfs as filesystem"
663	help
664	  The API is open but filesystem is not loaded. Clients can still do
665	  their work and read with debug tools that do not need
666	  debugfs filesystem.
667
668config DEBUG_FS_ALLOW_NONE
669	bool "No access"
670	help
671	  Access is off. Clients get -PERM when trying to create nodes in
672	  debugfs tree and debugfs is not registered as a filesystem.
673	  Client can then back-off or continue without debugfs access.
674
675endchoice
676
677source "lib/Kconfig.kgdb"
678source "lib/Kconfig.ubsan"
679source "lib/Kconfig.kcsan"
680
681endmenu
682
683menu "Networking Debugging"
684
685source "net/Kconfig.debug"
686
687endmenu # "Networking Debugging"
688
689menu "Memory Debugging"
690
691source "mm/Kconfig.debug"
692
693config DEBUG_OBJECTS
694	bool "Debug object operations"
695	depends on DEBUG_KERNEL
696	help
697	  If you say Y here, additional code will be inserted into the
698	  kernel to track the life time of various objects and validate
699	  the operations on those objects.
700
701config DEBUG_OBJECTS_SELFTEST
702	bool "Debug objects selftest"
703	depends on DEBUG_OBJECTS
704	help
705	  This enables the selftest of the object debug code.
706
707config DEBUG_OBJECTS_FREE
708	bool "Debug objects in freed memory"
709	depends on DEBUG_OBJECTS
710	help
711	  This enables checks whether a k/v free operation frees an area
712	  which contains an object which has not been deactivated
713	  properly. This can make kmalloc/kfree-intensive workloads
714	  much slower.
715
716config DEBUG_OBJECTS_TIMERS
717	bool "Debug timer objects"
718	depends on DEBUG_OBJECTS
719	help
720	  If you say Y here, additional code will be inserted into the
721	  timer routines to track the life time of timer objects and
722	  validate the timer operations.
723
724config DEBUG_OBJECTS_WORK
725	bool "Debug work objects"
726	depends on DEBUG_OBJECTS
727	help
728	  If you say Y here, additional code will be inserted into the
729	  work queue routines to track the life time of work objects and
730	  validate the work operations.
731
732config DEBUG_OBJECTS_RCU_HEAD
733	bool "Debug RCU callbacks objects"
734	depends on DEBUG_OBJECTS
735	help
736	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
737
738config DEBUG_OBJECTS_PERCPU_COUNTER
739	bool "Debug percpu counter objects"
740	depends on DEBUG_OBJECTS
741	help
742	  If you say Y here, additional code will be inserted into the
743	  percpu counter routines to track the life time of percpu counter
744	  objects and validate the percpu counter operations.
745
746config DEBUG_OBJECTS_ENABLE_DEFAULT
747	int "debug_objects bootup default value (0-1)"
748	range 0 1
749	default "1"
750	depends on DEBUG_OBJECTS
751	help
752	  Debug objects boot parameter default value
753
754config SHRINKER_DEBUG
755	bool "Enable shrinker debugging support"
756	depends on DEBUG_FS
757	help
758	  Say Y to enable the shrinker debugfs interface which provides
759	  visibility into the kernel memory shrinkers subsystem.
760	  Disable it to avoid an extra memory footprint.
761
762config DEBUG_STACK_USAGE
763	bool "Stack utilization instrumentation"
764	depends on DEBUG_KERNEL
765	help
766	  Enables the display of the minimum amount of free stack which each
767	  task has ever had available in the sysrq-T and sysrq-P debug output.
768
769	  This option will slow down process creation somewhat.
770
771config SCHED_STACK_END_CHECK
772	bool "Detect stack corruption on calls to schedule()"
773	depends on DEBUG_KERNEL
774	default n
775	help
776	  This option checks for a stack overrun on calls to schedule().
777	  If the stack end location is found to be over written always panic as
778	  the content of the corrupted region can no longer be trusted.
779	  This is to ensure no erroneous behaviour occurs which could result in
780	  data corruption or a sporadic crash at a later stage once the region
781	  is examined. The runtime overhead introduced is minimal.
782
783config ARCH_HAS_DEBUG_VM_PGTABLE
784	bool
785	help
786	  An architecture should select this when it can successfully
787	  build and run DEBUG_VM_PGTABLE.
788
789config DEBUG_VM_IRQSOFF
790	def_bool DEBUG_VM && !PREEMPT_RT
791
792config DEBUG_VM
793	bool "Debug VM"
794	depends on DEBUG_KERNEL
795	help
796	  Enable this to turn on extended checks in the virtual-memory system
797	  that may impact performance.
798
799	  If unsure, say N.
800
801config DEBUG_VM_SHOOT_LAZIES
802	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
803	depends on DEBUG_VM
804	depends on MMU_LAZY_TLB_SHOOTDOWN
805	help
806	  Enable additional IPIs that ensure lazy tlb mm references are removed
807	  before the mm is freed.
808
809	  If unsure, say N.
810
811config DEBUG_VM_MAPLE_TREE
812	bool "Debug VM maple trees"
813	depends on DEBUG_VM
814	select DEBUG_MAPLE_TREE
815	help
816	  Enable VM maple tree debugging information and extra validations.
817
818	  If unsure, say N.
819
820config DEBUG_VM_RB
821	bool "Debug VM red-black trees"
822	depends on DEBUG_VM
823	help
824	  Enable VM red-black tree debugging information and extra validations.
825
826	  If unsure, say N.
827
828config DEBUG_VM_PGFLAGS
829	bool "Debug page-flags operations"
830	depends on DEBUG_VM
831	help
832	  Enables extra validation on page flags operations.
833
834	  If unsure, say N.
835
836config DEBUG_VM_PGTABLE
837	bool "Debug arch page table for semantics compliance"
838	depends on MMU
839	depends on ARCH_HAS_DEBUG_VM_PGTABLE
840	default y if DEBUG_VM
841	help
842	  This option provides a debug method which can be used to test
843	  architecture page table helper functions on various platforms in
844	  verifying if they comply with expected generic MM semantics. This
845	  will help architecture code in making sure that any changes or
846	  new additions of these helpers still conform to expected
847	  semantics of the generic MM. Platforms will have to opt in for
848	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
849
850	  If unsure, say N.
851
852config ARCH_HAS_DEBUG_VIRTUAL
853	bool
854
855config DEBUG_VIRTUAL
856	bool "Debug VM translations"
857	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
858	help
859	  Enable some costly sanity checks in virtual to page code. This can
860	  catch mistakes with virt_to_page() and friends.
861
862	  If unsure, say N.
863
864config DEBUG_NOMMU_REGIONS
865	bool "Debug the global anon/private NOMMU mapping region tree"
866	depends on DEBUG_KERNEL && !MMU
867	help
868	  This option causes the global tree of anonymous and private mapping
869	  regions to be regularly checked for invalid topology.
870
871config DEBUG_MEMORY_INIT
872	bool "Debug memory initialisation" if EXPERT
873	default !EXPERT
874	help
875	  Enable this for additional checks during memory initialisation.
876	  The sanity checks verify aspects of the VM such as the memory model
877	  and other information provided by the architecture. Verbose
878	  information will be printed at KERN_DEBUG loglevel depending
879	  on the mminit_loglevel= command-line option.
880
881	  If unsure, say Y
882
883config MEMORY_NOTIFIER_ERROR_INJECT
884	tristate "Memory hotplug notifier error injection module"
885	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
886	help
887	  This option provides the ability to inject artificial errors to
888	  memory hotplug notifier chain callbacks.  It is controlled through
889	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
890
891	  If the notifier call chain should be failed with some events
892	  notified, write the error code to "actions/<notifier event>/error".
893
894	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
895
896	  # cd /sys/kernel/debug/notifier-error-inject/memory
897	  # echo -12 > actions/MEM_GOING_OFFLINE/error
898	  # echo offline > /sys/devices/system/memory/memoryXXX/state
899	  bash: echo: write error: Cannot allocate memory
900
901	  To compile this code as a module, choose M here: the module will
902	  be called memory-notifier-error-inject.
903
904	  If unsure, say N.
905
906config DEBUG_PER_CPU_MAPS
907	bool "Debug access to per_cpu maps"
908	depends on DEBUG_KERNEL
909	depends on SMP
910	help
911	  Say Y to verify that the per_cpu map being accessed has
912	  been set up. This adds a fair amount of code to kernel memory
913	  and decreases performance.
914
915	  Say N if unsure.
916
917config DEBUG_KMAP_LOCAL
918	bool "Debug kmap_local temporary mappings"
919	depends on DEBUG_KERNEL && KMAP_LOCAL
920	help
921	  This option enables additional error checking for the kmap_local
922	  infrastructure.  Disable for production use.
923
924config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
925	bool
926
927config DEBUG_KMAP_LOCAL_FORCE_MAP
928	bool "Enforce kmap_local temporary mappings"
929	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
930	select KMAP_LOCAL
931	select DEBUG_KMAP_LOCAL
932	help
933	  This option enforces temporary mappings through the kmap_local
934	  mechanism for non-highmem pages and on non-highmem systems.
935	  Disable this for production systems!
936
937config DEBUG_HIGHMEM
938	bool "Highmem debugging"
939	depends on DEBUG_KERNEL && HIGHMEM
940	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
941	select DEBUG_KMAP_LOCAL
942	help
943	  This option enables additional error checking for high memory
944	  systems.  Disable for production systems.
945
946config HAVE_DEBUG_STACKOVERFLOW
947	bool
948
949config DEBUG_STACKOVERFLOW
950	bool "Check for stack overflows"
951	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
952	help
953	  Say Y here if you want to check for overflows of kernel, IRQ
954	  and exception stacks (if your architecture uses them). This
955	  option will show detailed messages if free stack space drops
956	  below a certain limit.
957
958	  These kinds of bugs usually occur when call-chains in the
959	  kernel get too deep, especially when interrupts are
960	  involved.
961
962	  Use this in cases where you see apparently random memory
963	  corruption, especially if it appears in 'struct thread_info'
964
965	  If in doubt, say "N".
966
967source "lib/Kconfig.kasan"
968source "lib/Kconfig.kfence"
969source "lib/Kconfig.kmsan"
970
971endmenu # "Memory Debugging"
972
973config DEBUG_SHIRQ
974	bool "Debug shared IRQ handlers"
975	depends on DEBUG_KERNEL
976	help
977	  Enable this to generate a spurious interrupt just before a shared
978	  interrupt handler is deregistered (generating one when registering
979	  is currently disabled). Drivers need to handle this correctly. Some
980	  don't and need to be caught.
981
982menu "Debug Oops, Lockups and Hangs"
983
984config PANIC_ON_OOPS
985	bool "Panic on Oops"
986	help
987	  Say Y here to enable the kernel to panic when it oopses. This
988	  has the same effect as setting oops=panic on the kernel command
989	  line.
990
991	  This feature is useful to ensure that the kernel does not do
992	  anything erroneous after an oops which could result in data
993	  corruption or other issues.
994
995	  Say N if unsure.
996
997config PANIC_ON_OOPS_VALUE
998	int
999	range 0 1
1000	default 0 if !PANIC_ON_OOPS
1001	default 1 if PANIC_ON_OOPS
1002
1003config PANIC_TIMEOUT
1004	int "panic timeout"
1005	default 0
1006	help
1007	  Set the timeout value (in seconds) until a reboot occurs when
1008	  the kernel panics. If n = 0, then we wait forever. A timeout
1009	  value n > 0 will wait n seconds before rebooting, while a timeout
1010	  value n < 0 will reboot immediately.
1011
1012config LOCKUP_DETECTOR
1013	bool
1014
1015config SOFTLOCKUP_DETECTOR
1016	bool "Detect Soft Lockups"
1017	depends on DEBUG_KERNEL && !S390
1018	select LOCKUP_DETECTOR
1019	help
1020	  Say Y here to enable the kernel to act as a watchdog to detect
1021	  soft lockups.
1022
1023	  Softlockups are bugs that cause the kernel to loop in kernel
1024	  mode for more than 20 seconds, without giving other tasks a
1025	  chance to run.  The current stack trace is displayed upon
1026	  detection and the system will stay locked up.
1027
1028config BOOTPARAM_SOFTLOCKUP_PANIC
1029	bool "Panic (Reboot) On Soft Lockups"
1030	depends on SOFTLOCKUP_DETECTOR
1031	help
1032	  Say Y here to enable the kernel to panic on "soft lockups",
1033	  which are bugs that cause the kernel to loop in kernel
1034	  mode for more than 20 seconds (configurable using the watchdog_thresh
1035	  sysctl), without giving other tasks a chance to run.
1036
1037	  The panic can be used in combination with panic_timeout,
1038	  to cause the system to reboot automatically after a
1039	  lockup has been detected. This feature is useful for
1040	  high-availability systems that have uptime guarantees and
1041	  where a lockup must be resolved ASAP.
1042
1043	  Say N if unsure.
1044
1045config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1046	bool
1047	depends on SMP
1048	default y
1049
1050#
1051# Global switch whether to build a hardlockup detector at all. It is available
1052# only when the architecture supports at least one implementation. There are
1053# two exceptions. The hardlockup detector is never enabled on:
1054#
1055#	s390: it reported many false positives there
1056#
1057#	sparc64: has a custom implementation which is not using the common
1058#		hardlockup command line options and sysctl interface.
1059#
1060config HARDLOCKUP_DETECTOR
1061	bool "Detect Hard Lockups"
1062	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1063	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1064	imply HARDLOCKUP_DETECTOR_PERF
1065	imply HARDLOCKUP_DETECTOR_BUDDY
1066	imply HARDLOCKUP_DETECTOR_ARCH
1067	select LOCKUP_DETECTOR
1068
1069	help
1070	  Say Y here to enable the kernel to act as a watchdog to detect
1071	  hard lockups.
1072
1073	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1074	  for more than 10 seconds, without letting other interrupts have a
1075	  chance to run.  The current stack trace is displayed upon detection
1076	  and the system will stay locked up.
1077
1078#
1079# Note that arch-specific variants are always preferred.
1080#
1081config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1082	bool "Prefer the buddy CPU hardlockup detector"
1083	depends on HARDLOCKUP_DETECTOR
1084	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1085	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1086	help
1087	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1088
1089	  With the buddy detector, each CPU uses its softlockup hrtimer
1090	  to check that the next CPU is processing hrtimer interrupts by
1091	  verifying that a counter is increasing.
1092
1093	  This hardlockup detector is useful on systems that don't have
1094	  an arch-specific hardlockup detector or if resources needed
1095	  for the hardlockup detector are better used for other things.
1096
1097config HARDLOCKUP_DETECTOR_PERF
1098	bool
1099	depends on HARDLOCKUP_DETECTOR
1100	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1101	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1102	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1103
1104config HARDLOCKUP_DETECTOR_BUDDY
1105	bool
1106	depends on HARDLOCKUP_DETECTOR
1107	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1108	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1109	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1110	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1111
1112config HARDLOCKUP_DETECTOR_ARCH
1113	bool
1114	depends on HARDLOCKUP_DETECTOR
1115	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1116	help
1117	  The arch-specific implementation of the hardlockup detector will
1118	  be used.
1119
1120#
1121# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1122# interrupts. This config enables functions managing this common code.
1123#
1124config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1125	bool
1126	select SOFTLOCKUP_DETECTOR
1127
1128#
1129# Enables a timestamp based low pass filter to compensate for perf based
1130# hard lockup detection which runs too fast due to turbo modes.
1131#
1132config HARDLOCKUP_CHECK_TIMESTAMP
1133	bool
1134
1135config BOOTPARAM_HARDLOCKUP_PANIC
1136	bool "Panic (Reboot) On Hard Lockups"
1137	depends on HARDLOCKUP_DETECTOR
1138	help
1139	  Say Y here to enable the kernel to panic on "hard lockups",
1140	  which are bugs that cause the kernel to loop in kernel
1141	  mode with interrupts disabled for more than 10 seconds (configurable
1142	  using the watchdog_thresh sysctl).
1143
1144	  Say N if unsure.
1145
1146config DETECT_HUNG_TASK
1147	bool "Detect Hung Tasks"
1148	depends on DEBUG_KERNEL
1149	default SOFTLOCKUP_DETECTOR
1150	help
1151	  Say Y here to enable the kernel to detect "hung tasks",
1152	  which are bugs that cause the task to be stuck in
1153	  uninterruptible "D" state indefinitely.
1154
1155	  When a hung task is detected, the kernel will print the
1156	  current stack trace (which you should report), but the
1157	  task will stay in uninterruptible state. If lockdep is
1158	  enabled then all held locks will also be reported. This
1159	  feature has negligible overhead.
1160
1161config DEFAULT_HUNG_TASK_TIMEOUT
1162	int "Default timeout for hung task detection (in seconds)"
1163	depends on DETECT_HUNG_TASK
1164	default 120
1165	help
1166	  This option controls the default timeout (in seconds) used
1167	  to determine when a task has become non-responsive and should
1168	  be considered hung.
1169
1170	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1171	  sysctl or by writing a value to
1172	  /proc/sys/kernel/hung_task_timeout_secs.
1173
1174	  A timeout of 0 disables the check.  The default is two minutes.
1175	  Keeping the default should be fine in most cases.
1176
1177config BOOTPARAM_HUNG_TASK_PANIC
1178	bool "Panic (Reboot) On Hung Tasks"
1179	depends on DETECT_HUNG_TASK
1180	help
1181	  Say Y here to enable the kernel to panic on "hung tasks",
1182	  which are bugs that cause the kernel to leave a task stuck
1183	  in uninterruptible "D" state.
1184
1185	  The panic can be used in combination with panic_timeout,
1186	  to cause the system to reboot automatically after a
1187	  hung task has been detected. This feature is useful for
1188	  high-availability systems that have uptime guarantees and
1189	  where a hung tasks must be resolved ASAP.
1190
1191	  Say N if unsure.
1192
1193config WQ_WATCHDOG
1194	bool "Detect Workqueue Stalls"
1195	depends on DEBUG_KERNEL
1196	help
1197	  Say Y here to enable stall detection on workqueues.  If a
1198	  worker pool doesn't make forward progress on a pending work
1199	  item for over a given amount of time, 30s by default, a
1200	  warning message is printed along with dump of workqueue
1201	  state.  This can be configured through kernel parameter
1202	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1203
1204config WQ_CPU_INTENSIVE_REPORT
1205	bool "Report per-cpu work items which hog CPU for too long"
1206	depends on DEBUG_KERNEL
1207	help
1208	  Say Y here to enable reporting of concurrency-managed per-cpu work
1209	  items that hog CPUs for longer than
1210	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1211	  detects and excludes them from concurrency management to prevent
1212	  them from stalling other per-cpu work items. Occassional
1213	  triggering may not necessarily indicate a problem. Repeated
1214	  triggering likely indicates that the work item should be switched
1215	  to use an unbound workqueue.
1216
1217config TEST_LOCKUP
1218	tristate "Test module to generate lockups"
1219	depends on m
1220	help
1221	  This builds the "test_lockup" module that helps to make sure
1222	  that watchdogs and lockup detectors are working properly.
1223
1224	  Depending on module parameters it could emulate soft or hard
1225	  lockup, "hung task", or locking arbitrary lock for a long time.
1226	  Also it could generate series of lockups with cooling-down periods.
1227
1228	  If unsure, say N.
1229
1230endmenu # "Debug lockups and hangs"
1231
1232menu "Scheduler Debugging"
1233
1234config SCHED_DEBUG
1235	bool "Collect scheduler debugging info"
1236	depends on DEBUG_KERNEL && DEBUG_FS
1237	default y
1238	help
1239	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1240	  that can help debug the scheduler. The runtime overhead of this
1241	  option is minimal.
1242
1243config SCHED_INFO
1244	bool
1245	default n
1246
1247config SCHEDSTATS
1248	bool "Collect scheduler statistics"
1249	depends on DEBUG_KERNEL && PROC_FS
1250	select SCHED_INFO
1251	help
1252	  If you say Y here, additional code will be inserted into the
1253	  scheduler and related routines to collect statistics about
1254	  scheduler behavior and provide them in /proc/schedstat.  These
1255	  stats may be useful for both tuning and debugging the scheduler
1256	  If you aren't debugging the scheduler or trying to tune a specific
1257	  application, you can say N to avoid the very slight overhead
1258	  this adds.
1259
1260endmenu
1261
1262config DEBUG_TIMEKEEPING
1263	bool "Enable extra timekeeping sanity checking"
1264	help
1265	  This option will enable additional timekeeping sanity checks
1266	  which may be helpful when diagnosing issues where timekeeping
1267	  problems are suspected.
1268
1269	  This may include checks in the timekeeping hotpaths, so this
1270	  option may have a (very small) performance impact to some
1271	  workloads.
1272
1273	  If unsure, say N.
1274
1275config DEBUG_PREEMPT
1276	bool "Debug preemptible kernel"
1277	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1278	help
1279	  If you say Y here then the kernel will use a debug variant of the
1280	  commonly used smp_processor_id() function and will print warnings
1281	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1282	  will detect preemption count underflows.
1283
1284	  This option has potential to introduce high runtime overhead,
1285	  depending on workload as it triggers debugging routines for each
1286	  this_cpu operation. It should only be used for debugging purposes.
1287
1288menu "Lock Debugging (spinlocks, mutexes, etc...)"
1289
1290config LOCK_DEBUGGING_SUPPORT
1291	bool
1292	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1293	default y
1294
1295config PROVE_LOCKING
1296	bool "Lock debugging: prove locking correctness"
1297	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1298	select LOCKDEP
1299	select DEBUG_SPINLOCK
1300	select DEBUG_MUTEXES if !PREEMPT_RT
1301	select DEBUG_RT_MUTEXES if RT_MUTEXES
1302	select DEBUG_RWSEMS
1303	select DEBUG_WW_MUTEX_SLOWPATH
1304	select DEBUG_LOCK_ALLOC
1305	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1306	select TRACE_IRQFLAGS
1307	default n
1308	help
1309	 This feature enables the kernel to prove that all locking
1310	 that occurs in the kernel runtime is mathematically
1311	 correct: that under no circumstance could an arbitrary (and
1312	 not yet triggered) combination of observed locking
1313	 sequences (on an arbitrary number of CPUs, running an
1314	 arbitrary number of tasks and interrupt contexts) cause a
1315	 deadlock.
1316
1317	 In short, this feature enables the kernel to report locking
1318	 related deadlocks before they actually occur.
1319
1320	 The proof does not depend on how hard and complex a
1321	 deadlock scenario would be to trigger: how many
1322	 participant CPUs, tasks and irq-contexts would be needed
1323	 for it to trigger. The proof also does not depend on
1324	 timing: if a race and a resulting deadlock is possible
1325	 theoretically (no matter how unlikely the race scenario
1326	 is), it will be proven so and will immediately be
1327	 reported by the kernel (once the event is observed that
1328	 makes the deadlock theoretically possible).
1329
1330	 If a deadlock is impossible (i.e. the locking rules, as
1331	 observed by the kernel, are mathematically correct), the
1332	 kernel reports nothing.
1333
1334	 NOTE: this feature can also be enabled for rwlocks, mutexes
1335	 and rwsems - in which case all dependencies between these
1336	 different locking variants are observed and mapped too, and
1337	 the proof of observed correctness is also maintained for an
1338	 arbitrary combination of these separate locking variants.
1339
1340	 For more details, see Documentation/locking/lockdep-design.rst.
1341
1342config PROVE_RAW_LOCK_NESTING
1343	bool "Enable raw_spinlock - spinlock nesting checks"
1344	depends on PROVE_LOCKING
1345	default n
1346	help
1347	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1348	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1349	 not violated.
1350
1351	 NOTE: There are known nesting problems. So if you enable this
1352	 option expect lockdep splats until these problems have been fully
1353	 addressed which is work in progress. This config switch allows to
1354	 identify and analyze these problems. It will be removed and the
1355	 check permanently enabled once the main issues have been fixed.
1356
1357	 If unsure, select N.
1358
1359config LOCK_STAT
1360	bool "Lock usage statistics"
1361	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1362	select LOCKDEP
1363	select DEBUG_SPINLOCK
1364	select DEBUG_MUTEXES if !PREEMPT_RT
1365	select DEBUG_RT_MUTEXES if RT_MUTEXES
1366	select DEBUG_LOCK_ALLOC
1367	default n
1368	help
1369	 This feature enables tracking lock contention points
1370
1371	 For more details, see Documentation/locking/lockstat.rst
1372
1373	 This also enables lock events required by "perf lock",
1374	 subcommand of perf.
1375	 If you want to use "perf lock", you also need to turn on
1376	 CONFIG_EVENT_TRACING.
1377
1378	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1379	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1380
1381config DEBUG_RT_MUTEXES
1382	bool "RT Mutex debugging, deadlock detection"
1383	depends on DEBUG_KERNEL && RT_MUTEXES
1384	help
1385	 This allows rt mutex semantics violations and rt mutex related
1386	 deadlocks (lockups) to be detected and reported automatically.
1387
1388config DEBUG_SPINLOCK
1389	bool "Spinlock and rw-lock debugging: basic checks"
1390	depends on DEBUG_KERNEL
1391	select UNINLINE_SPIN_UNLOCK
1392	help
1393	  Say Y here and build SMP to catch missing spinlock initialization
1394	  and certain other kinds of spinlock errors commonly made.  This is
1395	  best used in conjunction with the NMI watchdog so that spinlock
1396	  deadlocks are also debuggable.
1397
1398config DEBUG_MUTEXES
1399	bool "Mutex debugging: basic checks"
1400	depends on DEBUG_KERNEL && !PREEMPT_RT
1401	help
1402	 This feature allows mutex semantics violations to be detected and
1403	 reported.
1404
1405config DEBUG_WW_MUTEX_SLOWPATH
1406	bool "Wait/wound mutex debugging: Slowpath testing"
1407	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1408	select DEBUG_LOCK_ALLOC
1409	select DEBUG_SPINLOCK
1410	select DEBUG_MUTEXES if !PREEMPT_RT
1411	select DEBUG_RT_MUTEXES if PREEMPT_RT
1412	help
1413	 This feature enables slowpath testing for w/w mutex users by
1414	 injecting additional -EDEADLK wound/backoff cases. Together with
1415	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1416	 will test all possible w/w mutex interface abuse with the
1417	 exception of simply not acquiring all the required locks.
1418	 Note that this feature can introduce significant overhead, so
1419	 it really should not be enabled in a production or distro kernel,
1420	 even a debug kernel.  If you are a driver writer, enable it.  If
1421	 you are a distro, do not.
1422
1423config DEBUG_RWSEMS
1424	bool "RW Semaphore debugging: basic checks"
1425	depends on DEBUG_KERNEL
1426	help
1427	  This debugging feature allows mismatched rw semaphore locks
1428	  and unlocks to be detected and reported.
1429
1430config DEBUG_LOCK_ALLOC
1431	bool "Lock debugging: detect incorrect freeing of live locks"
1432	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1433	select DEBUG_SPINLOCK
1434	select DEBUG_MUTEXES if !PREEMPT_RT
1435	select DEBUG_RT_MUTEXES if RT_MUTEXES
1436	select LOCKDEP
1437	help
1438	 This feature will check whether any held lock (spinlock, rwlock,
1439	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1440	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1441	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1442	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1443	 held during task exit.
1444
1445config LOCKDEP
1446	bool
1447	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1448	select STACKTRACE
1449	select KALLSYMS
1450	select KALLSYMS_ALL
1451
1452config LOCKDEP_SMALL
1453	bool
1454
1455config LOCKDEP_BITS
1456	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1457	depends on LOCKDEP && !LOCKDEP_SMALL
1458	range 10 30
1459	default 15
1460	help
1461	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1462
1463config LOCKDEP_CHAINS_BITS
1464	int "Bitsize for MAX_LOCKDEP_CHAINS"
1465	depends on LOCKDEP && !LOCKDEP_SMALL
1466	range 10 30
1467	default 16
1468	help
1469	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1470
1471config LOCKDEP_STACK_TRACE_BITS
1472	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1473	depends on LOCKDEP && !LOCKDEP_SMALL
1474	range 10 30
1475	default 19
1476	help
1477	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1478
1479config LOCKDEP_STACK_TRACE_HASH_BITS
1480	int "Bitsize for STACK_TRACE_HASH_SIZE"
1481	depends on LOCKDEP && !LOCKDEP_SMALL
1482	range 10 30
1483	default 14
1484	help
1485	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1486
1487config LOCKDEP_CIRCULAR_QUEUE_BITS
1488	int "Bitsize for elements in circular_queue struct"
1489	depends on LOCKDEP
1490	range 10 30
1491	default 12
1492	help
1493	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1494
1495config DEBUG_LOCKDEP
1496	bool "Lock dependency engine debugging"
1497	depends on DEBUG_KERNEL && LOCKDEP
1498	select DEBUG_IRQFLAGS
1499	help
1500	  If you say Y here, the lock dependency engine will do
1501	  additional runtime checks to debug itself, at the price
1502	  of more runtime overhead.
1503
1504config DEBUG_ATOMIC_SLEEP
1505	bool "Sleep inside atomic section checking"
1506	select PREEMPT_COUNT
1507	depends on DEBUG_KERNEL
1508	depends on !ARCH_NO_PREEMPT
1509	help
1510	  If you say Y here, various routines which may sleep will become very
1511	  noisy if they are called inside atomic sections: when a spinlock is
1512	  held, inside an rcu read side critical section, inside preempt disabled
1513	  sections, inside an interrupt, etc...
1514
1515config DEBUG_LOCKING_API_SELFTESTS
1516	bool "Locking API boot-time self-tests"
1517	depends on DEBUG_KERNEL
1518	help
1519	  Say Y here if you want the kernel to run a short self-test during
1520	  bootup. The self-test checks whether common types of locking bugs
1521	  are detected by debugging mechanisms or not. (if you disable
1522	  lock debugging then those bugs won't be detected of course.)
1523	  The following locking APIs are covered: spinlocks, rwlocks,
1524	  mutexes and rwsems.
1525
1526config LOCK_TORTURE_TEST
1527	tristate "torture tests for locking"
1528	depends on DEBUG_KERNEL
1529	select TORTURE_TEST
1530	help
1531	  This option provides a kernel module that runs torture tests
1532	  on kernel locking primitives.  The kernel module may be built
1533	  after the fact on the running kernel to be tested, if desired.
1534
1535	  Say Y here if you want kernel locking-primitive torture tests
1536	  to be built into the kernel.
1537	  Say M if you want these torture tests to build as a module.
1538	  Say N if you are unsure.
1539
1540config WW_MUTEX_SELFTEST
1541	tristate "Wait/wound mutex selftests"
1542	help
1543	  This option provides a kernel module that runs tests on the
1544	  on the struct ww_mutex locking API.
1545
1546	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1547	  with this test harness.
1548
1549	  Say M if you want these self tests to build as a module.
1550	  Say N if you are unsure.
1551
1552config SCF_TORTURE_TEST
1553	tristate "torture tests for smp_call_function*()"
1554	depends on DEBUG_KERNEL
1555	select TORTURE_TEST
1556	help
1557	  This option provides a kernel module that runs torture tests
1558	  on the smp_call_function() family of primitives.  The kernel
1559	  module may be built after the fact on the running kernel to
1560	  be tested, if desired.
1561
1562config CSD_LOCK_WAIT_DEBUG
1563	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1564	depends on DEBUG_KERNEL
1565	depends on 64BIT
1566	default n
1567	help
1568	  This option enables debug prints when CPUs are slow to respond
1569	  to the smp_call_function*() IPI wrappers.  These debug prints
1570	  include the IPI handler function currently executing (if any)
1571	  and relevant stack traces.
1572
1573config CSD_LOCK_WAIT_DEBUG_DEFAULT
1574	bool "Default csd_lock_wait() debugging on at boot time"
1575	depends on CSD_LOCK_WAIT_DEBUG
1576	depends on 64BIT
1577	default n
1578	help
1579	  This option causes the csdlock_debug= kernel boot parameter to
1580	  default to 1 (basic debugging) instead of 0 (no debugging).
1581
1582endmenu # lock debugging
1583
1584config TRACE_IRQFLAGS
1585	depends on TRACE_IRQFLAGS_SUPPORT
1586	bool
1587	help
1588	  Enables hooks to interrupt enabling and disabling for
1589	  either tracing or lock debugging.
1590
1591config TRACE_IRQFLAGS_NMI
1592	def_bool y
1593	depends on TRACE_IRQFLAGS
1594	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1595
1596config NMI_CHECK_CPU
1597	bool "Debugging for CPUs failing to respond to backtrace requests"
1598	depends on DEBUG_KERNEL
1599	depends on X86
1600	default n
1601	help
1602	  Enables debug prints when a CPU fails to respond to a given
1603	  backtrace NMI.  These prints provide some reasons why a CPU
1604	  might legitimately be failing to respond, for example, if it
1605	  is offline of if ignore_nmis is set.
1606
1607config DEBUG_IRQFLAGS
1608	bool "Debug IRQ flag manipulation"
1609	help
1610	  Enables checks for potentially unsafe enabling or disabling of
1611	  interrupts, such as calling raw_local_irq_restore() when interrupts
1612	  are enabled.
1613
1614config STACKTRACE
1615	bool "Stack backtrace support"
1616	depends on STACKTRACE_SUPPORT
1617	help
1618	  This option causes the kernel to create a /proc/pid/stack for
1619	  every process, showing its current stack trace.
1620	  It is also used by various kernel debugging features that require
1621	  stack trace generation.
1622
1623config WARN_ALL_UNSEEDED_RANDOM
1624	bool "Warn for all uses of unseeded randomness"
1625	default n
1626	help
1627	  Some parts of the kernel contain bugs relating to their use of
1628	  cryptographically secure random numbers before it's actually possible
1629	  to generate those numbers securely. This setting ensures that these
1630	  flaws don't go unnoticed, by enabling a message, should this ever
1631	  occur. This will allow people with obscure setups to know when things
1632	  are going wrong, so that they might contact developers about fixing
1633	  it.
1634
1635	  Unfortunately, on some models of some architectures getting
1636	  a fully seeded CRNG is extremely difficult, and so this can
1637	  result in dmesg getting spammed for a surprisingly long
1638	  time.  This is really bad from a security perspective, and
1639	  so architecture maintainers really need to do what they can
1640	  to get the CRNG seeded sooner after the system is booted.
1641	  However, since users cannot do anything actionable to
1642	  address this, by default this option is disabled.
1643
1644	  Say Y here if you want to receive warnings for all uses of
1645	  unseeded randomness.  This will be of use primarily for
1646	  those developers interested in improving the security of
1647	  Linux kernels running on their architecture (or
1648	  subarchitecture).
1649
1650config DEBUG_KOBJECT
1651	bool "kobject debugging"
1652	depends on DEBUG_KERNEL
1653	help
1654	  If you say Y here, some extra kobject debugging messages will be sent
1655	  to the syslog.
1656
1657config DEBUG_KOBJECT_RELEASE
1658	bool "kobject release debugging"
1659	depends on DEBUG_OBJECTS_TIMERS
1660	help
1661	  kobjects are reference counted objects.  This means that their
1662	  last reference count put is not predictable, and the kobject can
1663	  live on past the point at which a driver decides to drop its
1664	  initial reference to the kobject gained on allocation.  An
1665	  example of this would be a struct device which has just been
1666	  unregistered.
1667
1668	  However, some buggy drivers assume that after such an operation,
1669	  the memory backing the kobject can be immediately freed.  This
1670	  goes completely against the principles of a refcounted object.
1671
1672	  If you say Y here, the kernel will delay the release of kobjects
1673	  on the last reference count to improve the visibility of this
1674	  kind of kobject release bug.
1675
1676config HAVE_DEBUG_BUGVERBOSE
1677	bool
1678
1679menu "Debug kernel data structures"
1680
1681config DEBUG_LIST
1682	bool "Debug linked list manipulation"
1683	depends on DEBUG_KERNEL
1684	select LIST_HARDENED
1685	help
1686	  Enable this to turn on extended checks in the linked-list walking
1687	  routines.
1688
1689	  This option trades better quality error reports for performance, and
1690	  is more suitable for kernel debugging. If you care about performance,
1691	  you should only enable CONFIG_LIST_HARDENED instead.
1692
1693	  If unsure, say N.
1694
1695config DEBUG_PLIST
1696	bool "Debug priority linked list manipulation"
1697	depends on DEBUG_KERNEL
1698	help
1699	  Enable this to turn on extended checks in the priority-ordered
1700	  linked-list (plist) walking routines.  This checks the entire
1701	  list multiple times during each manipulation.
1702
1703	  If unsure, say N.
1704
1705config DEBUG_SG
1706	bool "Debug SG table operations"
1707	depends on DEBUG_KERNEL
1708	help
1709	  Enable this to turn on checks on scatter-gather tables. This can
1710	  help find problems with drivers that do not properly initialize
1711	  their sg tables.
1712
1713	  If unsure, say N.
1714
1715config DEBUG_NOTIFIERS
1716	bool "Debug notifier call chains"
1717	depends on DEBUG_KERNEL
1718	help
1719	  Enable this to turn on sanity checking for notifier call chains.
1720	  This is most useful for kernel developers to make sure that
1721	  modules properly unregister themselves from notifier chains.
1722	  This is a relatively cheap check but if you care about maximum
1723	  performance, say N.
1724
1725config DEBUG_CLOSURES
1726	bool "Debug closures (bcache async widgits)"
1727	depends on CLOSURES
1728	select DEBUG_FS
1729	help
1730	  Keeps all active closures in a linked list and provides a debugfs
1731	  interface to list them, which makes it possible to see asynchronous
1732	  operations that get stuck.
1733
1734config DEBUG_MAPLE_TREE
1735	bool "Debug maple trees"
1736	depends on DEBUG_KERNEL
1737	help
1738	  Enable maple tree debugging information and extra validations.
1739
1740	  If unsure, say N.
1741
1742endmenu
1743
1744config DEBUG_CREDENTIALS
1745	bool "Debug credential management"
1746	depends on DEBUG_KERNEL
1747	help
1748	  Enable this to turn on some debug checking for credential
1749	  management.  The additional code keeps track of the number of
1750	  pointers from task_structs to any given cred struct, and checks to
1751	  see that this number never exceeds the usage count of the cred
1752	  struct.
1753
1754	  Furthermore, if SELinux is enabled, this also checks that the
1755	  security pointer in the cred struct is never seen to be invalid.
1756
1757	  If unsure, say N.
1758
1759source "kernel/rcu/Kconfig.debug"
1760
1761config DEBUG_WQ_FORCE_RR_CPU
1762	bool "Force round-robin CPU selection for unbound work items"
1763	depends on DEBUG_KERNEL
1764	default n
1765	help
1766	  Workqueue used to implicitly guarantee that work items queued
1767	  without explicit CPU specified are put on the local CPU.  This
1768	  guarantee is no longer true and while local CPU is still
1769	  preferred work items may be put on foreign CPUs.  Kernel
1770	  parameter "workqueue.debug_force_rr_cpu" is added to force
1771	  round-robin CPU selection to flush out usages which depend on the
1772	  now broken guarantee.  This config option enables the debug
1773	  feature by default.  When enabled, memory and cache locality will
1774	  be impacted.
1775
1776config CPU_HOTPLUG_STATE_CONTROL
1777	bool "Enable CPU hotplug state control"
1778	depends on DEBUG_KERNEL
1779	depends on HOTPLUG_CPU
1780	default n
1781	help
1782	  Allows to write steps between "offline" and "online" to the CPUs
1783	  sysfs target file so states can be stepped granular. This is a debug
1784	  option for now as the hotplug machinery cannot be stopped and
1785	  restarted at arbitrary points yet.
1786
1787	  Say N if your are unsure.
1788
1789config LATENCYTOP
1790	bool "Latency measuring infrastructure"
1791	depends on DEBUG_KERNEL
1792	depends on STACKTRACE_SUPPORT
1793	depends on PROC_FS
1794	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1795	select KALLSYMS
1796	select KALLSYMS_ALL
1797	select STACKTRACE
1798	select SCHEDSTATS
1799	help
1800	  Enable this option if you want to use the LatencyTOP tool
1801	  to find out which userspace is blocking on what kernel operations.
1802
1803config DEBUG_CGROUP_REF
1804	bool "Disable inlining of cgroup css reference count functions"
1805	depends on DEBUG_KERNEL
1806	depends on CGROUPS
1807	depends on KPROBES
1808	default n
1809	help
1810	  Force cgroup css reference count functions to not be inlined so
1811	  that they can be kprobed for debugging.
1812
1813source "kernel/trace/Kconfig"
1814
1815config PROVIDE_OHCI1394_DMA_INIT
1816	bool "Remote debugging over FireWire early on boot"
1817	depends on PCI && X86
1818	help
1819	  If you want to debug problems which hang or crash the kernel early
1820	  on boot and the crashing machine has a FireWire port, you can use
1821	  this feature to remotely access the memory of the crashed machine
1822	  over FireWire. This employs remote DMA as part of the OHCI1394
1823	  specification which is now the standard for FireWire controllers.
1824
1825	  With remote DMA, you can monitor the printk buffer remotely using
1826	  firescope and access all memory below 4GB using fireproxy from gdb.
1827	  Even controlling a kernel debugger is possible using remote DMA.
1828
1829	  Usage:
1830
1831	  If ohci1394_dma=early is used as boot parameter, it will initialize
1832	  all OHCI1394 controllers which are found in the PCI config space.
1833
1834	  As all changes to the FireWire bus such as enabling and disabling
1835	  devices cause a bus reset and thereby disable remote DMA for all
1836	  devices, be sure to have the cable plugged and FireWire enabled on
1837	  the debugging host before booting the debug target for debugging.
1838
1839	  This code (~1k) is freed after boot. By then, the firewire stack
1840	  in charge of the OHCI-1394 controllers should be used instead.
1841
1842	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1843
1844source "samples/Kconfig"
1845
1846config ARCH_HAS_DEVMEM_IS_ALLOWED
1847	bool
1848
1849config STRICT_DEVMEM
1850	bool "Filter access to /dev/mem"
1851	depends on MMU && DEVMEM
1852	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1853	default y if PPC || X86 || ARM64
1854	help
1855	  If this option is disabled, you allow userspace (root) access to all
1856	  of memory, including kernel and userspace memory. Accidental
1857	  access to this is obviously disastrous, but specific access can
1858	  be used by people debugging the kernel. Note that with PAT support
1859	  enabled, even in this case there are restrictions on /dev/mem
1860	  use due to the cache aliasing requirements.
1861
1862	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1863	  file only allows userspace access to PCI space and the BIOS code and
1864	  data regions.  This is sufficient for dosemu and X and all common
1865	  users of /dev/mem.
1866
1867	  If in doubt, say Y.
1868
1869config IO_STRICT_DEVMEM
1870	bool "Filter I/O access to /dev/mem"
1871	depends on STRICT_DEVMEM
1872	help
1873	  If this option is disabled, you allow userspace (root) access to all
1874	  io-memory regardless of whether a driver is actively using that
1875	  range.  Accidental access to this is obviously disastrous, but
1876	  specific access can be used by people debugging kernel drivers.
1877
1878	  If this option is switched on, the /dev/mem file only allows
1879	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1880	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1881	  if the driver using a given range cannot be disabled.
1882
1883	  If in doubt, say Y.
1884
1885menu "$(SRCARCH) Debugging"
1886
1887source "arch/$(SRCARCH)/Kconfig.debug"
1888
1889endmenu
1890
1891menu "Kernel Testing and Coverage"
1892
1893source "lib/kunit/Kconfig"
1894
1895config NOTIFIER_ERROR_INJECTION
1896	tristate "Notifier error injection"
1897	depends on DEBUG_KERNEL
1898	select DEBUG_FS
1899	help
1900	  This option provides the ability to inject artificial errors to
1901	  specified notifier chain callbacks. It is useful to test the error
1902	  handling of notifier call chain failures.
1903
1904	  Say N if unsure.
1905
1906config PM_NOTIFIER_ERROR_INJECT
1907	tristate "PM notifier error injection module"
1908	depends on PM && NOTIFIER_ERROR_INJECTION
1909	default m if PM_DEBUG
1910	help
1911	  This option provides the ability to inject artificial errors to
1912	  PM notifier chain callbacks.  It is controlled through debugfs
1913	  interface /sys/kernel/debug/notifier-error-inject/pm
1914
1915	  If the notifier call chain should be failed with some events
1916	  notified, write the error code to "actions/<notifier event>/error".
1917
1918	  Example: Inject PM suspend error (-12 = -ENOMEM)
1919
1920	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1921	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1922	  # echo mem > /sys/power/state
1923	  bash: echo: write error: Cannot allocate memory
1924
1925	  To compile this code as a module, choose M here: the module will
1926	  be called pm-notifier-error-inject.
1927
1928	  If unsure, say N.
1929
1930config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1931	tristate "OF reconfig notifier error injection module"
1932	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1933	help
1934	  This option provides the ability to inject artificial errors to
1935	  OF reconfig notifier chain callbacks.  It is controlled
1936	  through debugfs interface under
1937	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1938
1939	  If the notifier call chain should be failed with some events
1940	  notified, write the error code to "actions/<notifier event>/error".
1941
1942	  To compile this code as a module, choose M here: the module will
1943	  be called of-reconfig-notifier-error-inject.
1944
1945	  If unsure, say N.
1946
1947config NETDEV_NOTIFIER_ERROR_INJECT
1948	tristate "Netdev notifier error injection module"
1949	depends on NET && NOTIFIER_ERROR_INJECTION
1950	help
1951	  This option provides the ability to inject artificial errors to
1952	  netdevice notifier chain callbacks.  It is controlled through debugfs
1953	  interface /sys/kernel/debug/notifier-error-inject/netdev
1954
1955	  If the notifier call chain should be failed with some events
1956	  notified, write the error code to "actions/<notifier event>/error".
1957
1958	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1959
1960	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1961	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1962	  # ip link set eth0 mtu 1024
1963	  RTNETLINK answers: Invalid argument
1964
1965	  To compile this code as a module, choose M here: the module will
1966	  be called netdev-notifier-error-inject.
1967
1968	  If unsure, say N.
1969
1970config FUNCTION_ERROR_INJECTION
1971	bool "Fault-injections of functions"
1972	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1973	help
1974	  Add fault injections into various functions that are annotated with
1975	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1976	  value of these functions. This is useful to test error paths of code.
1977
1978	  If unsure, say N
1979
1980config FAULT_INJECTION
1981	bool "Fault-injection framework"
1982	depends on DEBUG_KERNEL
1983	help
1984	  Provide fault-injection framework.
1985	  For more details, see Documentation/fault-injection/.
1986
1987config FAILSLAB
1988	bool "Fault-injection capability for kmalloc"
1989	depends on FAULT_INJECTION
1990	depends on SLAB || SLUB
1991	help
1992	  Provide fault-injection capability for kmalloc.
1993
1994config FAIL_PAGE_ALLOC
1995	bool "Fault-injection capability for alloc_pages()"
1996	depends on FAULT_INJECTION
1997	help
1998	  Provide fault-injection capability for alloc_pages().
1999
2000config FAULT_INJECTION_USERCOPY
2001	bool "Fault injection capability for usercopy functions"
2002	depends on FAULT_INJECTION
2003	help
2004	  Provides fault-injection capability to inject failures
2005	  in usercopy functions (copy_from_user(), get_user(), ...).
2006
2007config FAIL_MAKE_REQUEST
2008	bool "Fault-injection capability for disk IO"
2009	depends on FAULT_INJECTION && BLOCK
2010	help
2011	  Provide fault-injection capability for disk IO.
2012
2013config FAIL_IO_TIMEOUT
2014	bool "Fault-injection capability for faking disk interrupts"
2015	depends on FAULT_INJECTION && BLOCK
2016	help
2017	  Provide fault-injection capability on end IO handling. This
2018	  will make the block layer "forget" an interrupt as configured,
2019	  thus exercising the error handling.
2020
2021	  Only works with drivers that use the generic timeout handling,
2022	  for others it won't do anything.
2023
2024config FAIL_FUTEX
2025	bool "Fault-injection capability for futexes"
2026	select DEBUG_FS
2027	depends on FAULT_INJECTION && FUTEX
2028	help
2029	  Provide fault-injection capability for futexes.
2030
2031config FAULT_INJECTION_DEBUG_FS
2032	bool "Debugfs entries for fault-injection capabilities"
2033	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2034	help
2035	  Enable configuration of fault-injection capabilities via debugfs.
2036
2037config FAIL_FUNCTION
2038	bool "Fault-injection capability for functions"
2039	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2040	help
2041	  Provide function-based fault-injection capability.
2042	  This will allow you to override a specific function with a return
2043	  with given return value. As a result, function caller will see
2044	  an error value and have to handle it. This is useful to test the
2045	  error handling in various subsystems.
2046
2047config FAIL_MMC_REQUEST
2048	bool "Fault-injection capability for MMC IO"
2049	depends on FAULT_INJECTION_DEBUG_FS && MMC
2050	help
2051	  Provide fault-injection capability for MMC IO.
2052	  This will make the mmc core return data errors. This is
2053	  useful to test the error handling in the mmc block device
2054	  and to test how the mmc host driver handles retries from
2055	  the block device.
2056
2057config FAIL_SUNRPC
2058	bool "Fault-injection capability for SunRPC"
2059	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2060	help
2061	  Provide fault-injection capability for SunRPC and
2062	  its consumers.
2063
2064config FAULT_INJECTION_CONFIGFS
2065	bool "Configfs interface for fault-injection capabilities"
2066	depends on FAULT_INJECTION
2067	select CONFIGFS_FS
2068	help
2069	  This option allows configfs-based drivers to dynamically configure
2070	  fault-injection via configfs.  Each parameter for driver-specific
2071	  fault-injection can be made visible as a configfs attribute in a
2072	  configfs group.
2073
2074
2075config FAULT_INJECTION_STACKTRACE_FILTER
2076	bool "stacktrace filter for fault-injection capabilities"
2077	depends on FAULT_INJECTION
2078	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2079	select STACKTRACE
2080	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2081	help
2082	  Provide stacktrace filter for fault-injection capabilities
2083
2084config ARCH_HAS_KCOV
2085	bool
2086	help
2087	  An architecture should select this when it can successfully
2088	  build and run with CONFIG_KCOV. This typically requires
2089	  disabling instrumentation for some early boot code.
2090
2091config CC_HAS_SANCOV_TRACE_PC
2092	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2093
2094
2095config KCOV
2096	bool "Code coverage for fuzzing"
2097	depends on ARCH_HAS_KCOV
2098	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2099	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2100		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2101	select DEBUG_FS
2102	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2103	select OBJTOOL if HAVE_NOINSTR_HACK
2104	help
2105	  KCOV exposes kernel code coverage information in a form suitable
2106	  for coverage-guided fuzzing (randomized testing).
2107
2108	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
2109	  different machines and across reboots. If you need stable PC values,
2110	  disable RANDOMIZE_BASE.
2111
2112	  For more details, see Documentation/dev-tools/kcov.rst.
2113
2114config KCOV_ENABLE_COMPARISONS
2115	bool "Enable comparison operands collection by KCOV"
2116	depends on KCOV
2117	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2118	help
2119	  KCOV also exposes operands of every comparison in the instrumented
2120	  code along with operand sizes and PCs of the comparison instructions.
2121	  These operands can be used by fuzzing engines to improve the quality
2122	  of fuzzing coverage.
2123
2124config KCOV_INSTRUMENT_ALL
2125	bool "Instrument all code by default"
2126	depends on KCOV
2127	default y
2128	help
2129	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2130	  then you will want to instrument the whole kernel and you should
2131	  say y here. If you are doing more targeted fuzzing (like e.g.
2132	  filesystem fuzzing with AFL) then you will want to enable coverage
2133	  for more specific subsets of files, and should say n here.
2134
2135config KCOV_IRQ_AREA_SIZE
2136	hex "Size of interrupt coverage collection area in words"
2137	depends on KCOV
2138	default 0x40000
2139	help
2140	  KCOV uses preallocated per-cpu areas to collect coverage from
2141	  soft interrupts. This specifies the size of those areas in the
2142	  number of unsigned long words.
2143
2144menuconfig RUNTIME_TESTING_MENU
2145	bool "Runtime Testing"
2146	def_bool y
2147
2148if RUNTIME_TESTING_MENU
2149
2150config TEST_DHRY
2151	tristate "Dhrystone benchmark test"
2152	help
2153	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2154	  calculates the number of Dhrystones per second, and the number of
2155	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2156	  by 1757 (the number of Dhrystones per second obtained on the VAX
2157	  11/780, nominally a 1 MIPS machine).
2158
2159	  To run the benchmark, it needs to be enabled explicitly, either from
2160	  the kernel command line (when built-in), or from userspace (when
2161	  built-in or modular.
2162
2163	  Run once during kernel boot:
2164
2165	      test_dhry.run
2166
2167	  Set number of iterations from kernel command line:
2168
2169	      test_dhry.iterations=<n>
2170
2171	  Set number of iterations from userspace:
2172
2173	      echo <n> > /sys/module/test_dhry/parameters/iterations
2174
2175	  Trigger manual run from userspace:
2176
2177	      echo y > /sys/module/test_dhry/parameters/run
2178
2179	  If the number of iterations is <= 0, the test will devise a suitable
2180	  number of iterations (test runs for at least 2s) automatically.
2181	  This process takes ca. 4s.
2182
2183	  If unsure, say N.
2184
2185config LKDTM
2186	tristate "Linux Kernel Dump Test Tool Module"
2187	depends on DEBUG_FS
2188	help
2189	This module enables testing of the different dumping mechanisms by
2190	inducing system failures at predefined crash points.
2191	If you don't need it: say N
2192	Choose M here to compile this code as a module. The module will be
2193	called lkdtm.
2194
2195	Documentation on how to use the module can be found in
2196	Documentation/fault-injection/provoke-crashes.rst
2197
2198config CPUMASK_KUNIT_TEST
2199	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2200	depends on KUNIT
2201	default KUNIT_ALL_TESTS
2202	help
2203	  Enable to turn on cpumask tests, running at boot or module load time.
2204
2205	  For more information on KUnit and unit tests in general, please refer
2206	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2207
2208	  If unsure, say N.
2209
2210config TEST_LIST_SORT
2211	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2212	depends on KUNIT
2213	default KUNIT_ALL_TESTS
2214	help
2215	  Enable this to turn on 'list_sort()' function test. This test is
2216	  executed only once during system boot (so affects only boot time),
2217	  or at module load time.
2218
2219	  If unsure, say N.
2220
2221config TEST_MIN_HEAP
2222	tristate "Min heap test"
2223	depends on DEBUG_KERNEL || m
2224	help
2225	  Enable this to turn on min heap function tests. This test is
2226	  executed only once during system boot (so affects only boot time),
2227	  or at module load time.
2228
2229	  If unsure, say N.
2230
2231config TEST_SORT
2232	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2233	depends on KUNIT
2234	default KUNIT_ALL_TESTS
2235	help
2236	  This option enables the self-test function of 'sort()' at boot,
2237	  or at module load time.
2238
2239	  If unsure, say N.
2240
2241config TEST_DIV64
2242	tristate "64bit/32bit division and modulo test"
2243	depends on DEBUG_KERNEL || m
2244	help
2245	  Enable this to turn on 'do_div()' function test. This test is
2246	  executed only once during system boot (so affects only boot time),
2247	  or at module load time.
2248
2249	  If unsure, say N.
2250
2251config TEST_IOV_ITER
2252	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2253	depends on KUNIT
2254	default KUNIT_ALL_TESTS
2255	help
2256	  Enable this to turn on testing of the operation of the I/O iterator
2257	  (iov_iter). This test is executed only once during system boot (so
2258	  affects only boot time), or at module load time.
2259
2260	  If unsure, say N.
2261
2262config KPROBES_SANITY_TEST
2263	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2264	depends on DEBUG_KERNEL
2265	depends on KPROBES
2266	depends on KUNIT
2267	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2268	default KUNIT_ALL_TESTS
2269	help
2270	  This option provides for testing basic kprobes functionality on
2271	  boot. Samples of kprobe and kretprobe are inserted and
2272	  verified for functionality.
2273
2274	  Say N if you are unsure.
2275
2276config FPROBE_SANITY_TEST
2277	bool "Self test for fprobe"
2278	depends on DEBUG_KERNEL
2279	depends on FPROBE
2280	depends on KUNIT=y
2281	help
2282	  This option will enable testing the fprobe when the system boot.
2283	  A series of tests are made to verify that the fprobe is functioning
2284	  properly.
2285
2286	  Say N if you are unsure.
2287
2288config BACKTRACE_SELF_TEST
2289	tristate "Self test for the backtrace code"
2290	depends on DEBUG_KERNEL
2291	help
2292	  This option provides a kernel module that can be used to test
2293	  the kernel stack backtrace code. This option is not useful
2294	  for distributions or general kernels, but only for kernel
2295	  developers working on architecture code.
2296
2297	  Note that if you want to also test saved backtraces, you will
2298	  have to enable STACKTRACE as well.
2299
2300	  Say N if you are unsure.
2301
2302config TEST_REF_TRACKER
2303	tristate "Self test for reference tracker"
2304	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2305	select REF_TRACKER
2306	help
2307	  This option provides a kernel module performing tests
2308	  using reference tracker infrastructure.
2309
2310	  Say N if you are unsure.
2311
2312config RBTREE_TEST
2313	tristate "Red-Black tree test"
2314	depends on DEBUG_KERNEL
2315	help
2316	  A benchmark measuring the performance of the rbtree library.
2317	  Also includes rbtree invariant checks.
2318
2319config REED_SOLOMON_TEST
2320	tristate "Reed-Solomon library test"
2321	depends on DEBUG_KERNEL || m
2322	select REED_SOLOMON
2323	select REED_SOLOMON_ENC16
2324	select REED_SOLOMON_DEC16
2325	help
2326	  This option enables the self-test function of rslib at boot,
2327	  or at module load time.
2328
2329	  If unsure, say N.
2330
2331config INTERVAL_TREE_TEST
2332	tristate "Interval tree test"
2333	depends on DEBUG_KERNEL
2334	select INTERVAL_TREE
2335	help
2336	  A benchmark measuring the performance of the interval tree library
2337
2338config PERCPU_TEST
2339	tristate "Per cpu operations test"
2340	depends on m && DEBUG_KERNEL
2341	help
2342	  Enable this option to build test module which validates per-cpu
2343	  operations.
2344
2345	  If unsure, say N.
2346
2347config ATOMIC64_SELFTEST
2348	tristate "Perform an atomic64_t self-test"
2349	help
2350	  Enable this option to test the atomic64_t functions at boot or
2351	  at module load time.
2352
2353	  If unsure, say N.
2354
2355config ASYNC_RAID6_TEST
2356	tristate "Self test for hardware accelerated raid6 recovery"
2357	depends on ASYNC_RAID6_RECOV
2358	select ASYNC_MEMCPY
2359	help
2360	  This is a one-shot self test that permutes through the
2361	  recovery of all the possible two disk failure scenarios for a
2362	  N-disk array.  Recovery is performed with the asynchronous
2363	  raid6 recovery routines, and will optionally use an offload
2364	  engine if one is available.
2365
2366	  If unsure, say N.
2367
2368config TEST_HEXDUMP
2369	tristate "Test functions located in the hexdump module at runtime"
2370
2371config STRING_SELFTEST
2372	tristate "Test string functions at runtime"
2373
2374config TEST_STRING_HELPERS
2375	tristate "Test functions located in the string_helpers module at runtime"
2376
2377config TEST_KSTRTOX
2378	tristate "Test kstrto*() family of functions at runtime"
2379
2380config TEST_PRINTF
2381	tristate "Test printf() family of functions at runtime"
2382
2383config TEST_SCANF
2384	tristate "Test scanf() family of functions at runtime"
2385
2386config TEST_BITMAP
2387	tristate "Test bitmap_*() family of functions at runtime"
2388	help
2389	  Enable this option to test the bitmap functions at boot.
2390
2391	  If unsure, say N.
2392
2393config TEST_UUID
2394	tristate "Test functions located in the uuid module at runtime"
2395
2396config TEST_XARRAY
2397	tristate "Test the XArray code at runtime"
2398
2399config TEST_MAPLE_TREE
2400	tristate "Test the Maple Tree code at runtime or module load"
2401	help
2402	  Enable this option to test the maple tree code functions at boot, or
2403	  when the module is loaded. Enable "Debug Maple Trees" will enable
2404	  more verbose output on failures.
2405
2406	  If unsure, say N.
2407
2408config TEST_RHASHTABLE
2409	tristate "Perform selftest on resizable hash table"
2410	help
2411	  Enable this option to test the rhashtable functions at boot.
2412
2413	  If unsure, say N.
2414
2415config TEST_IDA
2416	tristate "Perform selftest on IDA functions"
2417
2418config TEST_PARMAN
2419	tristate "Perform selftest on priority array manager"
2420	depends on PARMAN
2421	help
2422	  Enable this option to test priority array manager on boot
2423	  (or module load).
2424
2425	  If unsure, say N.
2426
2427config TEST_IRQ_TIMINGS
2428	bool "IRQ timings selftest"
2429	depends on IRQ_TIMINGS
2430	help
2431	  Enable this option to test the irq timings code on boot.
2432
2433	  If unsure, say N.
2434
2435config TEST_LKM
2436	tristate "Test module loading with 'hello world' module"
2437	depends on m
2438	help
2439	  This builds the "test_module" module that emits "Hello, world"
2440	  on printk when loaded. It is designed to be used for basic
2441	  evaluation of the module loading subsystem (for example when
2442	  validating module verification). It lacks any extra dependencies,
2443	  and will not normally be loaded by the system unless explicitly
2444	  requested by name.
2445
2446	  If unsure, say N.
2447
2448config TEST_BITOPS
2449	tristate "Test module for compilation of bitops operations"
2450	depends on m
2451	help
2452	  This builds the "test_bitops" module that is much like the
2453	  TEST_LKM module except that it does a basic exercise of the
2454	  set/clear_bit macros and get_count_order/long to make sure there are
2455	  no compiler warnings from C=1 sparse checker or -Wextra
2456	  compilations. It has no dependencies and doesn't run or load unless
2457	  explicitly requested by name.  for example: modprobe test_bitops.
2458
2459	  If unsure, say N.
2460
2461config TEST_VMALLOC
2462	tristate "Test module for stress/performance analysis of vmalloc allocator"
2463	default n
2464       depends on MMU
2465	depends on m
2466	help
2467	  This builds the "test_vmalloc" module that should be used for
2468	  stress and performance analysis. So, any new change for vmalloc
2469	  subsystem can be evaluated from performance and stability point
2470	  of view.
2471
2472	  If unsure, say N.
2473
2474config TEST_USER_COPY
2475	tristate "Test user/kernel boundary protections"
2476	depends on m
2477	help
2478	  This builds the "test_user_copy" module that runs sanity checks
2479	  on the copy_to/from_user infrastructure, making sure basic
2480	  user/kernel boundary testing is working. If it fails to load,
2481	  a regression has been detected in the user/kernel memory boundary
2482	  protections.
2483
2484	  If unsure, say N.
2485
2486config TEST_BPF
2487	tristate "Test BPF filter functionality"
2488	depends on m && NET
2489	help
2490	  This builds the "test_bpf" module that runs various test vectors
2491	  against the BPF interpreter or BPF JIT compiler depending on the
2492	  current setting. This is in particular useful for BPF JIT compiler
2493	  development, but also to run regression tests against changes in
2494	  the interpreter code. It also enables test stubs for eBPF maps and
2495	  verifier used by user space verifier testsuite.
2496
2497	  If unsure, say N.
2498
2499config TEST_BLACKHOLE_DEV
2500	tristate "Test blackhole netdev functionality"
2501	depends on m && NET
2502	help
2503	  This builds the "test_blackhole_dev" module that validates the
2504	  data path through this blackhole netdev.
2505
2506	  If unsure, say N.
2507
2508config FIND_BIT_BENCHMARK
2509	tristate "Test find_bit functions"
2510	help
2511	  This builds the "test_find_bit" module that measure find_*_bit()
2512	  functions performance.
2513
2514	  If unsure, say N.
2515
2516config TEST_FIRMWARE
2517	tristate "Test firmware loading via userspace interface"
2518	depends on FW_LOADER
2519	help
2520	  This builds the "test_firmware" module that creates a userspace
2521	  interface for testing firmware loading. This can be used to
2522	  control the triggering of firmware loading without needing an
2523	  actual firmware-using device. The contents can be rechecked by
2524	  userspace.
2525
2526	  If unsure, say N.
2527
2528config TEST_SYSCTL
2529	tristate "sysctl test driver"
2530	depends on PROC_SYSCTL
2531	help
2532	  This builds the "test_sysctl" module. This driver enables to test the
2533	  proc sysctl interfaces available to drivers safely without affecting
2534	  production knobs which might alter system functionality.
2535
2536	  If unsure, say N.
2537
2538config BITFIELD_KUNIT
2539	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2540	depends on KUNIT
2541	default KUNIT_ALL_TESTS
2542	help
2543	  Enable this option to test the bitfield functions at boot.
2544
2545	  KUnit tests run during boot and output the results to the debug log
2546	  in TAP format (http://testanything.org/). Only useful for kernel devs
2547	  running the KUnit test harness, and not intended for inclusion into a
2548	  production build.
2549
2550	  For more information on KUnit and unit tests in general please refer
2551	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2552
2553	  If unsure, say N.
2554
2555config CHECKSUM_KUNIT
2556	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2557	depends on KUNIT
2558	default KUNIT_ALL_TESTS
2559	help
2560	  Enable this option to test the checksum functions at boot.
2561
2562	  KUnit tests run during boot and output the results to the debug log
2563	  in TAP format (http://testanything.org/). Only useful for kernel devs
2564	  running the KUnit test harness, and not intended for inclusion into a
2565	  production build.
2566
2567	  For more information on KUnit and unit tests in general please refer
2568	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2569
2570	  If unsure, say N.
2571
2572config HASH_KUNIT_TEST
2573	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2574	depends on KUNIT
2575	default KUNIT_ALL_TESTS
2576	help
2577	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2578	  integer (<linux/hash.h>) hash functions on boot.
2579
2580	  KUnit tests run during boot and output the results to the debug log
2581	  in TAP format (https://testanything.org/). Only useful for kernel devs
2582	  running the KUnit test harness, and not intended for inclusion into a
2583	  production build.
2584
2585	  For more information on KUnit and unit tests in general please refer
2586	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2587
2588	  This is intended to help people writing architecture-specific
2589	  optimized versions. If unsure, say N.
2590
2591config RESOURCE_KUNIT_TEST
2592	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2593	depends on KUNIT
2594	default KUNIT_ALL_TESTS
2595	help
2596	  This builds the resource API unit test.
2597	  Tests the logic of API provided by resource.c and ioport.h.
2598	  For more information on KUnit and unit tests in general please refer
2599	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2600
2601	  If unsure, say N.
2602
2603config SYSCTL_KUNIT_TEST
2604	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2605	depends on KUNIT
2606	default KUNIT_ALL_TESTS
2607	help
2608	  This builds the proc sysctl unit test, which runs on boot.
2609	  Tests the API contract and implementation correctness of sysctl.
2610	  For more information on KUnit and unit tests in general please refer
2611	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2612
2613	  If unsure, say N.
2614
2615config LIST_KUNIT_TEST
2616	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2617	depends on KUNIT
2618	default KUNIT_ALL_TESTS
2619	help
2620	  This builds the linked list KUnit test suite.
2621	  It tests that the API and basic functionality of the list_head type
2622	  and associated macros.
2623
2624	  KUnit tests run during boot and output the results to the debug log
2625	  in TAP format (https://testanything.org/). Only useful for kernel devs
2626	  running the KUnit test harness, and not intended for inclusion into a
2627	  production build.
2628
2629	  For more information on KUnit and unit tests in general please refer
2630	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2631
2632	  If unsure, say N.
2633
2634config HASHTABLE_KUNIT_TEST
2635	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2636	depends on KUNIT
2637	default KUNIT_ALL_TESTS
2638	help
2639	  This builds the hashtable KUnit test suite.
2640	  It tests the basic functionality of the API defined in
2641	  include/linux/hashtable.h. For more information on KUnit and
2642	  unit tests in general please refer to the KUnit documentation
2643	  in Documentation/dev-tools/kunit/.
2644
2645	  If unsure, say N.
2646
2647config LINEAR_RANGES_TEST
2648	tristate "KUnit test for linear_ranges"
2649	depends on KUNIT
2650	select LINEAR_RANGES
2651	help
2652	  This builds the linear_ranges unit test, which runs on boot.
2653	  Tests the linear_ranges logic correctness.
2654	  For more information on KUnit and unit tests in general please refer
2655	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2656
2657	  If unsure, say N.
2658
2659config CMDLINE_KUNIT_TEST
2660	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2661	depends on KUNIT
2662	default KUNIT_ALL_TESTS
2663	help
2664	  This builds the cmdline API unit test.
2665	  Tests the logic of API provided by cmdline.c.
2666	  For more information on KUnit and unit tests in general please refer
2667	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2668
2669	  If unsure, say N.
2670
2671config BITS_TEST
2672	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2673	depends on KUNIT
2674	default KUNIT_ALL_TESTS
2675	help
2676	  This builds the bits unit test.
2677	  Tests the logic of macros defined in bits.h.
2678	  For more information on KUnit and unit tests in general please refer
2679	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2680
2681	  If unsure, say N.
2682
2683config SLUB_KUNIT_TEST
2684	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2685	depends on SLUB_DEBUG && KUNIT
2686	default KUNIT_ALL_TESTS
2687	help
2688	  This builds SLUB allocator unit test.
2689	  Tests SLUB cache debugging functionality.
2690	  For more information on KUnit and unit tests in general please refer
2691	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2692
2693	  If unsure, say N.
2694
2695config RATIONAL_KUNIT_TEST
2696	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2697	depends on KUNIT && RATIONAL
2698	default KUNIT_ALL_TESTS
2699	help
2700	  This builds the rational math unit test.
2701	  For more information on KUnit and unit tests in general please refer
2702	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2703
2704	  If unsure, say N.
2705
2706config MEMCPY_KUNIT_TEST
2707	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2708	depends on KUNIT
2709	default KUNIT_ALL_TESTS
2710	help
2711	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2712	  For more information on KUnit and unit tests in general please refer
2713	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2714
2715	  If unsure, say N.
2716
2717config MEMCPY_SLOW_KUNIT_TEST
2718	bool "Include exhaustive memcpy tests"
2719	depends on MEMCPY_KUNIT_TEST
2720	default y
2721	help
2722	  Some memcpy tests are quite exhaustive in checking for overlaps
2723	  and bit ranges. These can be very slow, so they are split out
2724	  as a separate config, in case they need to be disabled.
2725
2726	  Note this config option will be replaced by the use of KUnit test
2727	  attributes.
2728
2729config IS_SIGNED_TYPE_KUNIT_TEST
2730	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2731	depends on KUNIT
2732	default KUNIT_ALL_TESTS
2733	help
2734	  Builds unit tests for the is_signed_type() macro.
2735
2736	  For more information on KUnit and unit tests in general please refer
2737	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2738
2739	  If unsure, say N.
2740
2741config OVERFLOW_KUNIT_TEST
2742	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2743	depends on KUNIT
2744	default KUNIT_ALL_TESTS
2745	help
2746	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2747	  related functions.
2748
2749	  For more information on KUnit and unit tests in general please refer
2750	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2751
2752	  If unsure, say N.
2753
2754config STACKINIT_KUNIT_TEST
2755	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2756	depends on KUNIT
2757	default KUNIT_ALL_TESTS
2758	help
2759	  Test if the kernel is zero-initializing stack variables and
2760	  padding. Coverage is controlled by compiler flags,
2761	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2762	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2763	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2764
2765config FORTIFY_KUNIT_TEST
2766	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2767	depends on KUNIT && FORTIFY_SOURCE
2768	default KUNIT_ALL_TESTS
2769	help
2770	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2771	  by the str*() and mem*() family of functions. For testing runtime
2772	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2773
2774config HW_BREAKPOINT_KUNIT_TEST
2775	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2776	depends on HAVE_HW_BREAKPOINT
2777	depends on KUNIT=y
2778	default KUNIT_ALL_TESTS
2779	help
2780	  Tests for hw_breakpoint constraints accounting.
2781
2782	  If unsure, say N.
2783
2784config STRCAT_KUNIT_TEST
2785	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2786	depends on KUNIT
2787	default KUNIT_ALL_TESTS
2788
2789config STRSCPY_KUNIT_TEST
2790	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2791	depends on KUNIT
2792	default KUNIT_ALL_TESTS
2793
2794config SIPHASH_KUNIT_TEST
2795	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2796	depends on KUNIT
2797	default KUNIT_ALL_TESTS
2798	help
2799	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2800	  functions on boot (or module load).
2801
2802	  This is intended to help people writing architecture-specific
2803	  optimized versions.  If unsure, say N.
2804
2805config TEST_UDELAY
2806	tristate "udelay test driver"
2807	help
2808	  This builds the "udelay_test" module that helps to make sure
2809	  that udelay() is working properly.
2810
2811	  If unsure, say N.
2812
2813config TEST_STATIC_KEYS
2814	tristate "Test static keys"
2815	depends on m
2816	help
2817	  Test the static key interfaces.
2818
2819	  If unsure, say N.
2820
2821config TEST_DYNAMIC_DEBUG
2822	tristate "Test DYNAMIC_DEBUG"
2823	depends on DYNAMIC_DEBUG
2824	help
2825	  This module registers a tracer callback to count enabled
2826	  pr_debugs in a 'do_debugging' function, then alters their
2827	  enablements, calls the function, and compares counts.
2828
2829	  If unsure, say N.
2830
2831config TEST_KMOD
2832	tristate "kmod stress tester"
2833	depends on m
2834	depends on NETDEVICES && NET_CORE && INET # for TUN
2835	depends on BLOCK
2836	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2837	select TEST_LKM
2838	select XFS_FS
2839	select TUN
2840	select BTRFS_FS
2841	help
2842	  Test the kernel's module loading mechanism: kmod. kmod implements
2843	  support to load modules using the Linux kernel's usermode helper.
2844	  This test provides a series of tests against kmod.
2845
2846	  Although technically you can either build test_kmod as a module or
2847	  into the kernel we disallow building it into the kernel since
2848	  it stress tests request_module() and this will very likely cause
2849	  some issues by taking over precious threads available from other
2850	  module load requests, ultimately this could be fatal.
2851
2852	  To run tests run:
2853
2854	  tools/testing/selftests/kmod/kmod.sh --help
2855
2856	  If unsure, say N.
2857
2858config TEST_DEBUG_VIRTUAL
2859	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2860	depends on DEBUG_VIRTUAL
2861	help
2862	  Test the kernel's ability to detect incorrect calls to
2863	  virt_to_phys() done against the non-linear part of the
2864	  kernel's virtual address map.
2865
2866	  If unsure, say N.
2867
2868config TEST_MEMCAT_P
2869	tristate "Test memcat_p() helper function"
2870	help
2871	  Test the memcat_p() helper for correctly merging two
2872	  pointer arrays together.
2873
2874	  If unsure, say N.
2875
2876config TEST_LIVEPATCH
2877	tristate "Test livepatching"
2878	default n
2879	depends on DYNAMIC_DEBUG
2880	depends on LIVEPATCH
2881	depends on m
2882	help
2883	  Test kernel livepatching features for correctness.  The tests will
2884	  load test modules that will be livepatched in various scenarios.
2885
2886	  To run all the livepatching tests:
2887
2888	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2889
2890	  Alternatively, individual tests may be invoked:
2891
2892	  tools/testing/selftests/livepatch/test-callbacks.sh
2893	  tools/testing/selftests/livepatch/test-livepatch.sh
2894	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2895
2896	  If unsure, say N.
2897
2898config TEST_OBJAGG
2899	tristate "Perform selftest on object aggreration manager"
2900	default n
2901	depends on OBJAGG
2902	help
2903	  Enable this option to test object aggregation manager on boot
2904	  (or module load).
2905
2906config TEST_MEMINIT
2907	tristate "Test heap/page initialization"
2908	help
2909	  Test if the kernel is zero-initializing heap and page allocations.
2910	  This can be useful to test init_on_alloc and init_on_free features.
2911
2912	  If unsure, say N.
2913
2914config TEST_HMM
2915	tristate "Test HMM (Heterogeneous Memory Management)"
2916	depends on TRANSPARENT_HUGEPAGE
2917	depends on DEVICE_PRIVATE
2918	select HMM_MIRROR
2919	select MMU_NOTIFIER
2920	help
2921	  This is a pseudo device driver solely for testing HMM.
2922	  Say M here if you want to build the HMM test module.
2923	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2924
2925	  If unsure, say N.
2926
2927config TEST_FREE_PAGES
2928	tristate "Test freeing pages"
2929	help
2930	  Test that a memory leak does not occur due to a race between
2931	  freeing a block of pages and a speculative page reference.
2932	  Loading this module is safe if your kernel has the bug fixed.
2933	  If the bug is not fixed, it will leak gigabytes of memory and
2934	  probably OOM your system.
2935
2936config TEST_FPU
2937	tristate "Test floating point operations in kernel space"
2938	depends on X86 && !KCOV_INSTRUMENT_ALL
2939	help
2940	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2941	  which will trigger a sequence of floating point operations. This is used
2942	  for self-testing floating point control register setting in
2943	  kernel_fpu_begin().
2944
2945	  If unsure, say N.
2946
2947config TEST_CLOCKSOURCE_WATCHDOG
2948	tristate "Test clocksource watchdog in kernel space"
2949	depends on CLOCKSOURCE_WATCHDOG
2950	help
2951	  Enable this option to create a kernel module that will trigger
2952	  a test of the clocksource watchdog.  This module may be loaded
2953	  via modprobe or insmod in which case it will run upon being
2954	  loaded, or it may be built in, in which case it will run
2955	  shortly after boot.
2956
2957	  If unsure, say N.
2958
2959config TEST_OBJPOOL
2960	tristate "Test module for correctness and stress of objpool"
2961	default n
2962	depends on m && DEBUG_KERNEL
2963	help
2964	  This builds the "test_objpool" module that should be used for
2965	  correctness verification and concurrent testings of objects
2966	  allocation and reclamation.
2967
2968	  If unsure, say N.
2969
2970endif # RUNTIME_TESTING_MENU
2971
2972config ARCH_USE_MEMTEST
2973	bool
2974	help
2975	  An architecture should select this when it uses early_memtest()
2976	  during boot process.
2977
2978config MEMTEST
2979	bool "Memtest"
2980	depends on ARCH_USE_MEMTEST
2981	help
2982	  This option adds a kernel parameter 'memtest', which allows memtest
2983	  to be set and executed.
2984	        memtest=0, mean disabled; -- default
2985	        memtest=1, mean do 1 test pattern;
2986	        ...
2987	        memtest=17, mean do 17 test patterns.
2988	  If you are unsure how to answer this question, answer N.
2989
2990
2991
2992config HYPERV_TESTING
2993	bool "Microsoft Hyper-V driver testing"
2994	default n
2995	depends on HYPERV && DEBUG_FS
2996	help
2997	  Select this option to enable Hyper-V vmbus testing.
2998
2999endmenu # "Kernel Testing and Coverage"
3000
3001menu "Rust hacking"
3002
3003config RUST_DEBUG_ASSERTIONS
3004	bool "Debug assertions"
3005	depends on RUST
3006	help
3007	  Enables rustc's `-Cdebug-assertions` codegen option.
3008
3009	  This flag lets you turn `cfg(debug_assertions)` conditional
3010	  compilation on or off. This can be used to enable extra debugging
3011	  code in development but not in production. For example, it controls
3012	  the behavior of the standard library's `debug_assert!` macro.
3013
3014	  Note that this will apply to all Rust code, including `core`.
3015
3016	  If unsure, say N.
3017
3018config RUST_OVERFLOW_CHECKS
3019	bool "Overflow checks"
3020	default y
3021	depends on RUST
3022	help
3023	  Enables rustc's `-Coverflow-checks` codegen option.
3024
3025	  This flag allows you to control the behavior of runtime integer
3026	  overflow. When overflow-checks are enabled, a Rust panic will occur
3027	  on overflow.
3028
3029	  Note that this will apply to all Rust code, including `core`.
3030
3031	  If unsure, say Y.
3032
3033config RUST_BUILD_ASSERT_ALLOW
3034	bool "Allow unoptimized build-time assertions"
3035	depends on RUST
3036	help
3037	  Controls how are `build_error!` and `build_assert!` handled during build.
3038
3039	  If calls to them exist in the binary, it may indicate a violated invariant
3040	  or that the optimizer failed to verify the invariant during compilation.
3041
3042	  This should not happen, thus by default the build is aborted. However,
3043	  as an escape hatch, you can choose Y here to ignore them during build
3044	  and let the check be carried at runtime (with `panic!` being called if
3045	  the check fails).
3046
3047	  If unsure, say N.
3048
3049config RUST_KERNEL_DOCTESTS
3050	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3051	depends on RUST && KUNIT=y
3052	default KUNIT_ALL_TESTS
3053	help
3054	  This builds the documentation tests of the `kernel` crate
3055	  as KUnit tests.
3056
3057	  For more information on KUnit and unit tests in general,
3058	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3059
3060	  If unsure, say N.
3061
3062endmenu # "Rust"
3063
3064endmenu # Kernel hacking
3065