xref: /linux/lib/Kconfig.debug (revision 229087f6)
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 type information"
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	# pahole uses elfutils, which does not have support for Hexagon relocations
384	depends on !HEXAGON
385	help
386	  Generate deduplicated BTF type information from DWARF debug info.
387	  Turning this on expects presence of pahole tool, which will convert
388	  DWARF type info into equivalent deduplicated BTF type info.
389
390config PAHOLE_HAS_SPLIT_BTF
391	def_bool PAHOLE_VERSION >= 119
392
393config PAHOLE_HAS_BTF_TAG
394	def_bool PAHOLE_VERSION >= 123
395	depends on CC_IS_CLANG
396	help
397	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
398	  btf_decl_tag) or not. Currently only clang compiler implements
399	  these attributes, so make the config depend on CC_IS_CLANG.
400
401config PAHOLE_HAS_LANG_EXCLUDE
402	def_bool PAHOLE_VERSION >= 124
403	help
404	  Support for the --lang_exclude flag which makes pahole exclude
405	  compilation units from the supplied language. Used in Kbuild to
406	  omit Rust CUs which are not supported in version 1.24 of pahole,
407	  otherwise it would emit malformed kernel and module binaries when
408	  using DEBUG_INFO_BTF_MODULES.
409
410config DEBUG_INFO_BTF_MODULES
411	bool "Generate BTF type information for kernel modules"
412	default y
413	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
414	help
415	  Generate compact split BTF type information for kernel modules.
416
417config MODULE_ALLOW_BTF_MISMATCH
418	bool "Allow loading modules with non-matching BTF type info"
419	depends on DEBUG_INFO_BTF_MODULES
420	help
421	  For modules whose split BTF does not match vmlinux, load without
422	  BTF rather than refusing to load. The default behavior with
423	  module BTF enabled is to reject modules with such mismatches;
424	  this option will still load module BTF where possible but ignore
425	  it when a mismatch is found.
426
427config GDB_SCRIPTS
428	bool "Provide GDB scripts for kernel debugging"
429	help
430	  This creates the required links to GDB helper scripts in the
431	  build directory. If you load vmlinux into gdb, the helper
432	  scripts will be automatically imported by gdb as well, and
433	  additional functions are available to analyze a Linux kernel
434	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
435	  for further details.
436
437endif # DEBUG_INFO
438
439config FRAME_WARN
440	int "Warn for stack frames larger than"
441	range 0 8192
442	default 0 if KMSAN
443	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
444	default 2048 if PARISC
445	default 1536 if (!64BIT && XTENSA)
446	default 1280 if KASAN && !64BIT
447	default 1024 if !64BIT
448	default 2048 if 64BIT
449	help
450	  Tell the compiler to warn at build time for stack frames larger than this.
451	  Setting this too low will cause a lot of warnings.
452	  Setting it to 0 disables the warning.
453
454config STRIP_ASM_SYMS
455	bool "Strip assembler-generated symbols during link"
456	default n
457	help
458	  Strip internal assembler-generated symbols during a link (symbols
459	  that look like '.Lxxx') so they don't pollute the output of
460	  get_wchan() and suchlike.
461
462config READABLE_ASM
463	bool "Generate readable assembler code"
464	depends on DEBUG_KERNEL
465	depends on CC_IS_GCC
466	help
467	  Disable some compiler optimizations that tend to generate human unreadable
468	  assembler output. This may make the kernel slightly slower, but it helps
469	  to keep kernel developers who have to stare a lot at assembler listings
470	  sane.
471
472config HEADERS_INSTALL
473	bool "Install uapi headers to usr/include"
474	depends on !UML
475	help
476	  This option will install uapi headers (headers exported to user-space)
477	  into the usr/include directory for use during the kernel build.
478	  This is unneeded for building the kernel itself, but needed for some
479	  user-space program samples. It is also needed by some features such
480	  as uapi header sanity checks.
481
482config DEBUG_SECTION_MISMATCH
483	bool "Enable full Section mismatch analysis"
484	depends on CC_IS_GCC
485	help
486	  The section mismatch analysis checks if there are illegal
487	  references from one section to another section.
488	  During linktime or runtime, some sections are dropped;
489	  any use of code/data previously in these sections would
490	  most likely result in an oops.
491	  In the code, functions and variables are annotated with
492	  __init,, etc. (see the full list in include/linux/init.h),
493	  which results in the code/data being placed in specific sections.
494	  The section mismatch analysis is always performed after a full
495	  kernel build, and enabling this option causes the following
496	  additional step to occur:
497	  - Add the option -fno-inline-functions-called-once to gcc commands.
498	    When inlining a function annotated with __init in a non-init
499	    function, we would lose the section information and thus
500	    the analysis would not catch the illegal reference.
501	    This option tells gcc to inline less (but it does result in
502	    a larger kernel).
503
504config SECTION_MISMATCH_WARN_ONLY
505	bool "Make section mismatch errors non-fatal"
506	default y
507	help
508	  If you say N here, the build process will fail if there are any
509	  section mismatch, instead of just throwing warnings.
510
511	  If unsure, say Y.
512
513config DEBUG_FORCE_FUNCTION_ALIGN_64B
514	bool "Force all function address 64B aligned"
515	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
516	select FUNCTION_ALIGNMENT_64B
517	help
518	  There are cases that a commit from one domain changes the function
519	  address alignment of other domains, and cause magic performance
520	  bump (regression or improvement). Enable this option will help to
521	  verify if the bump is caused by function alignment changes, while
522	  it will slightly increase the kernel size and affect icache usage.
523
524	  It is mainly for debug and performance tuning use.
525
526#
527# Select this config option from the architecture Kconfig, if it
528# is preferred to always offer frame pointers as a config
529# option on the architecture (regardless of KERNEL_DEBUG):
530#
531config ARCH_WANT_FRAME_POINTERS
532	bool
533
534config FRAME_POINTER
535	bool "Compile the kernel with frame pointers"
536	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
537	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
538	help
539	  If you say Y here the resulting kernel image will be slightly
540	  larger and slower, but it gives very useful debugging information
541	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
542
543config OBJTOOL
544	bool
545
546config STACK_VALIDATION
547	bool "Compile-time stack metadata validation"
548	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
549	select OBJTOOL
550	default n
551	help
552	  Validate frame pointer rules at compile-time.  This helps ensure that
553	  runtime stack traces are more reliable.
554
555	  For more information, see
556	  tools/objtool/Documentation/objtool.txt.
557
558config NOINSTR_VALIDATION
559	bool
560	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
561	select OBJTOOL
562	default y
563
564config VMLINUX_MAP
565	bool "Generate vmlinux.map file when linking"
566	depends on EXPERT
567	help
568	  Selecting this option will pass "-Map=vmlinux.map" to ld
569	  when linking vmlinux. That file can be useful for verifying
570	  and debugging magic section games, and for seeing which
571	  pieces of code get eliminated with
572	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
573
574config DEBUG_FORCE_WEAK_PER_CPU
575	bool "Force weak per-cpu definitions"
576	depends on DEBUG_KERNEL
577	help
578	  s390 and alpha require percpu variables in modules to be
579	  defined weak to work around addressing range issue which
580	  puts the following two restrictions on percpu variable
581	  definitions.
582
583	  1. percpu symbols must be unique whether static or not
584	  2. percpu variables can't be defined inside a function
585
586	  To ensure that generic code follows the above rules, this
587	  option forces all percpu variables to be defined as weak.
588
589endmenu # "Compiler options"
590
591menu "Generic Kernel Debugging Instruments"
592
593config MAGIC_SYSRQ
594	bool "Magic SysRq key"
595	depends on !UML
596	help
597	  If you say Y here, you will have some control over the system even
598	  if the system crashes for example during kernel debugging (e.g., you
599	  will be able to flush the buffer cache to disk, reboot the system
600	  immediately or dump some status information). This is accomplished
601	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
602	  also works on a serial console (on PC hardware at least), if you
603	  send a BREAK and then within 5 seconds a command keypress. The
604	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
605	  Don't say Y unless you really know what this hack does.
606
607config MAGIC_SYSRQ_DEFAULT_ENABLE
608	hex "Enable magic SysRq key functions by default"
609	depends on MAGIC_SYSRQ
610	default 0x1
611	help
612	  Specifies which SysRq key functions are enabled by default.
613	  This may be set to 1 or 0 to enable or disable them all, or
614	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
615
616config MAGIC_SYSRQ_SERIAL
617	bool "Enable magic SysRq key over serial"
618	depends on MAGIC_SYSRQ
619	default y
620	help
621	  Many embedded boards have a disconnected TTL level serial which can
622	  generate some garbage that can lead to spurious false sysrq detects.
623	  This option allows you to decide whether you want to enable the
624	  magic SysRq key.
625
626config MAGIC_SYSRQ_SERIAL_SEQUENCE
627	string "Char sequence that enables magic SysRq over serial"
628	depends on MAGIC_SYSRQ_SERIAL
629	default ""
630	help
631	  Specifies a sequence of characters that can follow BREAK to enable
632	  SysRq on a serial console.
633
634	  If unsure, leave an empty string and the option will not be enabled.
635
636config DEBUG_FS
637	bool "Debug Filesystem"
638	help
639	  debugfs is a virtual file system that kernel developers use to put
640	  debugging files into.  Enable this option to be able to read and
641	  write to these files.
642
643	  For detailed documentation on the debugfs API, see
644	  Documentation/filesystems/.
645
646	  If unsure, say N.
647
648choice
649	prompt "Debugfs default access"
650	depends on DEBUG_FS
651	default DEBUG_FS_ALLOW_ALL
652	help
653	  This selects the default access restrictions for debugfs.
654	  It can be overridden with kernel command line option
655	  debugfs=[on,no-mount,off]. The restrictions apply for API access
656	  and filesystem registration.
657
658config DEBUG_FS_ALLOW_ALL
659	bool "Access normal"
660	help
661	  No restrictions apply. Both API and filesystem registration
662	  is on. This is the normal default operation.
663
664config DEBUG_FS_DISALLOW_MOUNT
665	bool "Do not register debugfs as filesystem"
666	help
667	  The API is open but filesystem is not loaded. Clients can still do
668	  their work and read with debug tools that do not need
669	  debugfs filesystem.
670
671config DEBUG_FS_ALLOW_NONE
672	bool "No access"
673	help
674	  Access is off. Clients get -PERM when trying to create nodes in
675	  debugfs tree and debugfs is not registered as a filesystem.
676	  Client can then back-off or continue without debugfs access.
677
678endchoice
679
680source "lib/Kconfig.kgdb"
681source "lib/Kconfig.ubsan"
682source "lib/Kconfig.kcsan"
683
684endmenu
685
686menu "Networking Debugging"
687
688source "net/Kconfig.debug"
689
690endmenu # "Networking Debugging"
691
692menu "Memory Debugging"
693
694source "mm/Kconfig.debug"
695
696config DEBUG_OBJECTS
697	bool "Debug object operations"
698	depends on DEBUG_KERNEL
699	help
700	  If you say Y here, additional code will be inserted into the
701	  kernel to track the life time of various objects and validate
702	  the operations on those objects.
703
704config DEBUG_OBJECTS_SELFTEST
705	bool "Debug objects selftest"
706	depends on DEBUG_OBJECTS
707	help
708	  This enables the selftest of the object debug code.
709
710config DEBUG_OBJECTS_FREE
711	bool "Debug objects in freed memory"
712	depends on DEBUG_OBJECTS
713	help
714	  This enables checks whether a k/v free operation frees an area
715	  which contains an object which has not been deactivated
716	  properly. This can make kmalloc/kfree-intensive workloads
717	  much slower.
718
719config DEBUG_OBJECTS_TIMERS
720	bool "Debug timer objects"
721	depends on DEBUG_OBJECTS
722	help
723	  If you say Y here, additional code will be inserted into the
724	  timer routines to track the life time of timer objects and
725	  validate the timer operations.
726
727config DEBUG_OBJECTS_WORK
728	bool "Debug work objects"
729	depends on DEBUG_OBJECTS
730	help
731	  If you say Y here, additional code will be inserted into the
732	  work queue routines to track the life time of work objects and
733	  validate the work operations.
734
735config DEBUG_OBJECTS_RCU_HEAD
736	bool "Debug RCU callbacks objects"
737	depends on DEBUG_OBJECTS
738	help
739	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
740
741config DEBUG_OBJECTS_PERCPU_COUNTER
742	bool "Debug percpu counter objects"
743	depends on DEBUG_OBJECTS
744	help
745	  If you say Y here, additional code will be inserted into the
746	  percpu counter routines to track the life time of percpu counter
747	  objects and validate the percpu counter operations.
748
749config DEBUG_OBJECTS_ENABLE_DEFAULT
750	int "debug_objects bootup default value (0-1)"
751	range 0 1
752	default "1"
753	depends on DEBUG_OBJECTS
754	help
755	  Debug objects boot parameter default value
756
757config SHRINKER_DEBUG
758	bool "Enable shrinker debugging support"
759	depends on DEBUG_FS
760	help
761	  Say Y to enable the shrinker debugfs interface which provides
762	  visibility into the kernel memory shrinkers subsystem.
763	  Disable it to avoid an extra memory footprint.
764
765config DEBUG_STACK_USAGE
766	bool "Stack utilization instrumentation"
767	depends on DEBUG_KERNEL
768	help
769	  Enables the display of the minimum amount of free stack which each
770	  task has ever had available in the sysrq-T and sysrq-P debug output.
771	  Also emits a message to dmesg when a process exits if that process
772	  used more stack space than previously exiting processes.
773
774	  This option will slow down process creation somewhat.
775
776config SCHED_STACK_END_CHECK
777	bool "Detect stack corruption on calls to schedule()"
778	depends on DEBUG_KERNEL
779	default n
780	help
781	  This option checks for a stack overrun on calls to schedule().
782	  If the stack end location is found to be over written always panic as
783	  the content of the corrupted region can no longer be trusted.
784	  This is to ensure no erroneous behaviour occurs which could result in
785	  data corruption or a sporadic crash at a later stage once the region
786	  is examined. The runtime overhead introduced is minimal.
787
788config ARCH_HAS_DEBUG_VM_PGTABLE
789	bool
790	help
791	  An architecture should select this when it can successfully
792	  build and run DEBUG_VM_PGTABLE.
793
794config DEBUG_VM_IRQSOFF
795	def_bool DEBUG_VM && !PREEMPT_RT
796
797config DEBUG_VM
798	bool "Debug VM"
799	depends on DEBUG_KERNEL
800	help
801	  Enable this to turn on extended checks in the virtual-memory system
802	  that may impact performance.
803
804	  If unsure, say N.
805
806config DEBUG_VM_SHOOT_LAZIES
807	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
808	depends on DEBUG_VM
809	depends on MMU_LAZY_TLB_SHOOTDOWN
810	help
811	  Enable additional IPIs that ensure lazy tlb mm references are removed
812	  before the mm is freed.
813
814	  If unsure, say N.
815
816config DEBUG_VM_MAPLE_TREE
817	bool "Debug VM maple trees"
818	depends on DEBUG_VM
819	select DEBUG_MAPLE_TREE
820	help
821	  Enable VM maple tree debugging information and extra validations.
822
823	  If unsure, say N.
824
825config DEBUG_VM_RB
826	bool "Debug VM red-black trees"
827	depends on DEBUG_VM
828	help
829	  Enable VM red-black tree debugging information and extra validations.
830
831	  If unsure, say N.
832
833config DEBUG_VM_PGFLAGS
834	bool "Debug page-flags operations"
835	depends on DEBUG_VM
836	help
837	  Enables extra validation on page flags operations.
838
839	  If unsure, say N.
840
841config DEBUG_VM_PGTABLE
842	bool "Debug arch page table for semantics compliance"
843	depends on MMU
844	depends on ARCH_HAS_DEBUG_VM_PGTABLE
845	default y if DEBUG_VM
846	help
847	  This option provides a debug method which can be used to test
848	  architecture page table helper functions on various platforms in
849	  verifying if they comply with expected generic MM semantics. This
850	  will help architecture code in making sure that any changes or
851	  new additions of these helpers still conform to expected
852	  semantics of the generic MM. Platforms will have to opt in for
853	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
854
855	  If unsure, say N.
856
857config ARCH_HAS_DEBUG_VIRTUAL
858	bool
859
860config DEBUG_VIRTUAL
861	bool "Debug VM translations"
862	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
863	help
864	  Enable some costly sanity checks in virtual to page code. This can
865	  catch mistakes with virt_to_page() and friends.
866
867	  If unsure, say N.
868
869config DEBUG_NOMMU_REGIONS
870	bool "Debug the global anon/private NOMMU mapping region tree"
871	depends on DEBUG_KERNEL && !MMU
872	help
873	  This option causes the global tree of anonymous and private mapping
874	  regions to be regularly checked for invalid topology.
875
876config DEBUG_MEMORY_INIT
877	bool "Debug memory initialisation" if EXPERT
878	default !EXPERT
879	help
880	  Enable this for additional checks during memory initialisation.
881	  The sanity checks verify aspects of the VM such as the memory model
882	  and other information provided by the architecture. Verbose
883	  information will be printed at KERN_DEBUG loglevel depending
884	  on the mminit_loglevel= command-line option.
885
886	  If unsure, say Y
887
888config MEMORY_NOTIFIER_ERROR_INJECT
889	tristate "Memory hotplug notifier error injection module"
890	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
891	help
892	  This option provides the ability to inject artificial errors to
893	  memory hotplug notifier chain callbacks.  It is controlled through
894	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
895
896	  If the notifier call chain should be failed with some events
897	  notified, write the error code to "actions/<notifier event>/error".
898
899	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
900
901	  # cd /sys/kernel/debug/notifier-error-inject/memory
902	  # echo -12 > actions/MEM_GOING_OFFLINE/error
903	  # echo offline > /sys/devices/system/memory/memoryXXX/state
904	  bash: echo: write error: Cannot allocate memory
905
906	  To compile this code as a module, choose M here: the module will
907	  be called memory-notifier-error-inject.
908
909	  If unsure, say N.
910
911config DEBUG_PER_CPU_MAPS
912	bool "Debug access to per_cpu maps"
913	depends on DEBUG_KERNEL
914	depends on SMP
915	help
916	  Say Y to verify that the per_cpu map being accessed has
917	  been set up. This adds a fair amount of code to kernel memory
918	  and decreases performance.
919
920	  Say N if unsure.
921
922config DEBUG_KMAP_LOCAL
923	bool "Debug kmap_local temporary mappings"
924	depends on DEBUG_KERNEL && KMAP_LOCAL
925	help
926	  This option enables additional error checking for the kmap_local
927	  infrastructure.  Disable for production use.
928
929config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
930	bool
931
932config DEBUG_KMAP_LOCAL_FORCE_MAP
933	bool "Enforce kmap_local temporary mappings"
934	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
935	select KMAP_LOCAL
936	select DEBUG_KMAP_LOCAL
937	help
938	  This option enforces temporary mappings through the kmap_local
939	  mechanism for non-highmem pages and on non-highmem systems.
940	  Disable this for production systems!
941
942config DEBUG_HIGHMEM
943	bool "Highmem debugging"
944	depends on DEBUG_KERNEL && HIGHMEM
945	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
946	select DEBUG_KMAP_LOCAL
947	help
948	  This option enables additional error checking for high memory
949	  systems.  Disable for production systems.
950
951config HAVE_DEBUG_STACKOVERFLOW
952	bool
953
954config DEBUG_STACKOVERFLOW
955	bool "Check for stack overflows"
956	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
957	help
958	  Say Y here if you want to check for overflows of kernel, IRQ
959	  and exception stacks (if your architecture uses them). This
960	  option will show detailed messages if free stack space drops
961	  below a certain limit.
962
963	  These kinds of bugs usually occur when call-chains in the
964	  kernel get too deep, especially when interrupts are
965	  involved.
966
967	  Use this in cases where you see apparently random memory
968	  corruption, especially if it appears in 'struct thread_info'
969
970	  If in doubt, say "N".
971
972source "lib/Kconfig.kasan"
973source "lib/Kconfig.kfence"
974source "lib/Kconfig.kmsan"
975
976endmenu # "Memory Debugging"
977
978config DEBUG_SHIRQ
979	bool "Debug shared IRQ handlers"
980	depends on DEBUG_KERNEL
981	help
982	  Enable this to generate a spurious interrupt just before a shared
983	  interrupt handler is deregistered (generating one when registering
984	  is currently disabled). Drivers need to handle this correctly. Some
985	  don't and need to be caught.
986
987menu "Debug Oops, Lockups and Hangs"
988
989config PANIC_ON_OOPS
990	bool "Panic on Oops"
991	help
992	  Say Y here to enable the kernel to panic when it oopses. This
993	  has the same effect as setting oops=panic on the kernel command
994	  line.
995
996	  This feature is useful to ensure that the kernel does not do
997	  anything erroneous after an oops which could result in data
998	  corruption or other issues.
999
1000	  Say N if unsure.
1001
1002config PANIC_ON_OOPS_VALUE
1003	int
1004	range 0 1
1005	default 0 if !PANIC_ON_OOPS
1006	default 1 if PANIC_ON_OOPS
1007
1008config PANIC_TIMEOUT
1009	int "panic timeout"
1010	default 0
1011	help
1012	  Set the timeout value (in seconds) until a reboot occurs when
1013	  the kernel panics. If n = 0, then we wait forever. A timeout
1014	  value n > 0 will wait n seconds before rebooting, while a timeout
1015	  value n < 0 will reboot immediately.
1016
1017config LOCKUP_DETECTOR
1018	bool
1019
1020config SOFTLOCKUP_DETECTOR
1021	bool "Detect Soft Lockups"
1022	depends on DEBUG_KERNEL && !S390
1023	select LOCKUP_DETECTOR
1024	help
1025	  Say Y here to enable the kernel to act as a watchdog to detect
1026	  soft lockups.
1027
1028	  Softlockups are bugs that cause the kernel to loop in kernel
1029	  mode for more than 20 seconds, without giving other tasks a
1030	  chance to run.  The current stack trace is displayed upon
1031	  detection and the system will stay locked up.
1032
1033config BOOTPARAM_SOFTLOCKUP_PANIC
1034	bool "Panic (Reboot) On Soft Lockups"
1035	depends on SOFTLOCKUP_DETECTOR
1036	help
1037	  Say Y here to enable the kernel to panic on "soft lockups",
1038	  which are bugs that cause the kernel to loop in kernel
1039	  mode for more than 20 seconds (configurable using the watchdog_thresh
1040	  sysctl), without giving other tasks a chance to run.
1041
1042	  The panic can be used in combination with panic_timeout,
1043	  to cause the system to reboot automatically after a
1044	  lockup has been detected. This feature is useful for
1045	  high-availability systems that have uptime guarantees and
1046	  where a lockup must be resolved ASAP.
1047
1048	  Say N if unsure.
1049
1050config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1051	bool
1052	depends on SMP
1053	default y
1054
1055#
1056# Global switch whether to build a hardlockup detector at all. It is available
1057# only when the architecture supports at least one implementation. There are
1058# two exceptions. The hardlockup detector is never enabled on:
1059#
1060#	s390: it reported many false positives there
1061#
1062#	sparc64: has a custom implementation which is not using the common
1063#		hardlockup command line options and sysctl interface.
1064#
1065config HARDLOCKUP_DETECTOR
1066	bool "Detect Hard Lockups"
1067	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1068	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1069	imply HARDLOCKUP_DETECTOR_PERF
1070	imply HARDLOCKUP_DETECTOR_BUDDY
1071	imply HARDLOCKUP_DETECTOR_ARCH
1072	select LOCKUP_DETECTOR
1073
1074	help
1075	  Say Y here to enable the kernel to act as a watchdog to detect
1076	  hard lockups.
1077
1078	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1079	  for more than 10 seconds, without letting other interrupts have a
1080	  chance to run.  The current stack trace is displayed upon detection
1081	  and the system will stay locked up.
1082
1083#
1084# Note that arch-specific variants are always preferred.
1085#
1086config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1087	bool "Prefer the buddy CPU hardlockup detector"
1088	depends on HARDLOCKUP_DETECTOR
1089	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1090	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1091	help
1092	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1093
1094	  With the buddy detector, each CPU uses its softlockup hrtimer
1095	  to check that the next CPU is processing hrtimer interrupts by
1096	  verifying that a counter is increasing.
1097
1098	  This hardlockup detector is useful on systems that don't have
1099	  an arch-specific hardlockup detector or if resources needed
1100	  for the hardlockup detector are better used for other things.
1101
1102config HARDLOCKUP_DETECTOR_PERF
1103	bool
1104	depends on HARDLOCKUP_DETECTOR
1105	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1106	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1107	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1108
1109config HARDLOCKUP_DETECTOR_BUDDY
1110	bool
1111	depends on HARDLOCKUP_DETECTOR
1112	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1113	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1114	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1115	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1116
1117config HARDLOCKUP_DETECTOR_ARCH
1118	bool
1119	depends on HARDLOCKUP_DETECTOR
1120	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1121	help
1122	  The arch-specific implementation of the hardlockup detector will
1123	  be used.
1124
1125#
1126# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1127# interrupts. This config enables functions managing this common code.
1128#
1129config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1130	bool
1131	select SOFTLOCKUP_DETECTOR
1132
1133#
1134# Enables a timestamp based low pass filter to compensate for perf based
1135# hard lockup detection which runs too fast due to turbo modes.
1136#
1137config HARDLOCKUP_CHECK_TIMESTAMP
1138	bool
1139
1140config BOOTPARAM_HARDLOCKUP_PANIC
1141	bool "Panic (Reboot) On Hard Lockups"
1142	depends on HARDLOCKUP_DETECTOR
1143	help
1144	  Say Y here to enable the kernel to panic on "hard lockups",
1145	  which are bugs that cause the kernel to loop in kernel
1146	  mode with interrupts disabled for more than 10 seconds (configurable
1147	  using the watchdog_thresh sysctl).
1148
1149	  Say N if unsure.
1150
1151config DETECT_HUNG_TASK
1152	bool "Detect Hung Tasks"
1153	depends on DEBUG_KERNEL
1154	default SOFTLOCKUP_DETECTOR
1155	help
1156	  Say Y here to enable the kernel to detect "hung tasks",
1157	  which are bugs that cause the task to be stuck in
1158	  uninterruptible "D" state indefinitely.
1159
1160	  When a hung task is detected, the kernel will print the
1161	  current stack trace (which you should report), but the
1162	  task will stay in uninterruptible state. If lockdep is
1163	  enabled then all held locks will also be reported. This
1164	  feature has negligible overhead.
1165
1166config DEFAULT_HUNG_TASK_TIMEOUT
1167	int "Default timeout for hung task detection (in seconds)"
1168	depends on DETECT_HUNG_TASK
1169	default 120
1170	help
1171	  This option controls the default timeout (in seconds) used
1172	  to determine when a task has become non-responsive and should
1173	  be considered hung.
1174
1175	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1176	  sysctl or by writing a value to
1177	  /proc/sys/kernel/hung_task_timeout_secs.
1178
1179	  A timeout of 0 disables the check.  The default is two minutes.
1180	  Keeping the default should be fine in most cases.
1181
1182config BOOTPARAM_HUNG_TASK_PANIC
1183	bool "Panic (Reboot) On Hung Tasks"
1184	depends on DETECT_HUNG_TASK
1185	help
1186	  Say Y here to enable the kernel to panic on "hung tasks",
1187	  which are bugs that cause the kernel to leave a task stuck
1188	  in uninterruptible "D" state.
1189
1190	  The panic can be used in combination with panic_timeout,
1191	  to cause the system to reboot automatically after a
1192	  hung task has been detected. This feature is useful for
1193	  high-availability systems that have uptime guarantees and
1194	  where a hung tasks must be resolved ASAP.
1195
1196	  Say N if unsure.
1197
1198config WQ_WATCHDOG
1199	bool "Detect Workqueue Stalls"
1200	depends on DEBUG_KERNEL
1201	help
1202	  Say Y here to enable stall detection on workqueues.  If a
1203	  worker pool doesn't make forward progress on a pending work
1204	  item for over a given amount of time, 30s by default, a
1205	  warning message is printed along with dump of workqueue
1206	  state.  This can be configured through kernel parameter
1207	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1208
1209config WQ_CPU_INTENSIVE_REPORT
1210	bool "Report per-cpu work items which hog CPU for too long"
1211	depends on DEBUG_KERNEL
1212	help
1213	  Say Y here to enable reporting of concurrency-managed per-cpu work
1214	  items that hog CPUs for longer than
1215	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1216	  detects and excludes them from concurrency management to prevent
1217	  them from stalling other per-cpu work items. Occassional
1218	  triggering may not necessarily indicate a problem. Repeated
1219	  triggering likely indicates that the work item should be switched
1220	  to use an unbound workqueue.
1221
1222config TEST_LOCKUP
1223	tristate "Test module to generate lockups"
1224	depends on m
1225	help
1226	  This builds the "test_lockup" module that helps to make sure
1227	  that watchdogs and lockup detectors are working properly.
1228
1229	  Depending on module parameters it could emulate soft or hard
1230	  lockup, "hung task", or locking arbitrary lock for a long time.
1231	  Also it could generate series of lockups with cooling-down periods.
1232
1233	  If unsure, say N.
1234
1235endmenu # "Debug lockups and hangs"
1236
1237menu "Scheduler Debugging"
1238
1239config SCHED_DEBUG
1240	bool "Collect scheduler debugging info"
1241	depends on DEBUG_KERNEL && DEBUG_FS
1242	default y
1243	help
1244	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1245	  that can help debug the scheduler. The runtime overhead of this
1246	  option is minimal.
1247
1248config SCHED_INFO
1249	bool
1250	default n
1251
1252config SCHEDSTATS
1253	bool "Collect scheduler statistics"
1254	depends on DEBUG_KERNEL && PROC_FS
1255	select SCHED_INFO
1256	help
1257	  If you say Y here, additional code will be inserted into the
1258	  scheduler and related routines to collect statistics about
1259	  scheduler behavior and provide them in /proc/schedstat.  These
1260	  stats may be useful for both tuning and debugging the scheduler
1261	  If you aren't debugging the scheduler or trying to tune a specific
1262	  application, you can say N to avoid the very slight overhead
1263	  this adds.
1264
1265endmenu
1266
1267config DEBUG_TIMEKEEPING
1268	bool "Enable extra timekeeping sanity checking"
1269	help
1270	  This option will enable additional timekeeping sanity checks
1271	  which may be helpful when diagnosing issues where timekeeping
1272	  problems are suspected.
1273
1274	  This may include checks in the timekeeping hotpaths, so this
1275	  option may have a (very small) performance impact to some
1276	  workloads.
1277
1278	  If unsure, say N.
1279
1280config DEBUG_PREEMPT
1281	bool "Debug preemptible kernel"
1282	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1283	help
1284	  If you say Y here then the kernel will use a debug variant of the
1285	  commonly used smp_processor_id() function and will print warnings
1286	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1287	  will detect preemption count underflows.
1288
1289	  This option has potential to introduce high runtime overhead,
1290	  depending on workload as it triggers debugging routines for each
1291	  this_cpu operation. It should only be used for debugging purposes.
1292
1293menu "Lock Debugging (spinlocks, mutexes, etc...)"
1294
1295config LOCK_DEBUGGING_SUPPORT
1296	bool
1297	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1298	default y
1299
1300config PROVE_LOCKING
1301	bool "Lock debugging: prove locking correctness"
1302	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1303	select LOCKDEP
1304	select DEBUG_SPINLOCK
1305	select DEBUG_MUTEXES if !PREEMPT_RT
1306	select DEBUG_RT_MUTEXES if RT_MUTEXES
1307	select DEBUG_RWSEMS if !PREEMPT_RT
1308	select DEBUG_WW_MUTEX_SLOWPATH
1309	select DEBUG_LOCK_ALLOC
1310	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1311	select TRACE_IRQFLAGS
1312	default n
1313	help
1314	 This feature enables the kernel to prove that all locking
1315	 that occurs in the kernel runtime is mathematically
1316	 correct: that under no circumstance could an arbitrary (and
1317	 not yet triggered) combination of observed locking
1318	 sequences (on an arbitrary number of CPUs, running an
1319	 arbitrary number of tasks and interrupt contexts) cause a
1320	 deadlock.
1321
1322	 In short, this feature enables the kernel to report locking
1323	 related deadlocks before they actually occur.
1324
1325	 The proof does not depend on how hard and complex a
1326	 deadlock scenario would be to trigger: how many
1327	 participant CPUs, tasks and irq-contexts would be needed
1328	 for it to trigger. The proof also does not depend on
1329	 timing: if a race and a resulting deadlock is possible
1330	 theoretically (no matter how unlikely the race scenario
1331	 is), it will be proven so and will immediately be
1332	 reported by the kernel (once the event is observed that
1333	 makes the deadlock theoretically possible).
1334
1335	 If a deadlock is impossible (i.e. the locking rules, as
1336	 observed by the kernel, are mathematically correct), the
1337	 kernel reports nothing.
1338
1339	 NOTE: this feature can also be enabled for rwlocks, mutexes
1340	 and rwsems - in which case all dependencies between these
1341	 different locking variants are observed and mapped too, and
1342	 the proof of observed correctness is also maintained for an
1343	 arbitrary combination of these separate locking variants.
1344
1345	 For more details, see Documentation/locking/lockdep-design.rst.
1346
1347config PROVE_RAW_LOCK_NESTING
1348	bool "Enable raw_spinlock - spinlock nesting checks"
1349	depends on PROVE_LOCKING
1350	default n
1351	help
1352	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1353	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1354	 not violated.
1355
1356	 NOTE: There are known nesting problems. So if you enable this
1357	 option expect lockdep splats until these problems have been fully
1358	 addressed which is work in progress. This config switch allows to
1359	 identify and analyze these problems. It will be removed and the
1360	 check permanently enabled once the main issues have been fixed.
1361
1362	 If unsure, select N.
1363
1364config LOCK_STAT
1365	bool "Lock usage statistics"
1366	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1367	select LOCKDEP
1368	select DEBUG_SPINLOCK
1369	select DEBUG_MUTEXES if !PREEMPT_RT
1370	select DEBUG_RT_MUTEXES if RT_MUTEXES
1371	select DEBUG_LOCK_ALLOC
1372	default n
1373	help
1374	 This feature enables tracking lock contention points
1375
1376	 For more details, see Documentation/locking/lockstat.rst
1377
1378	 This also enables lock events required by "perf lock",
1379	 subcommand of perf.
1380	 If you want to use "perf lock", you also need to turn on
1381	 CONFIG_EVENT_TRACING.
1382
1383	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1384	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1385
1386config DEBUG_RT_MUTEXES
1387	bool "RT Mutex debugging, deadlock detection"
1388	depends on DEBUG_KERNEL && RT_MUTEXES
1389	help
1390	 This allows rt mutex semantics violations and rt mutex related
1391	 deadlocks (lockups) to be detected and reported automatically.
1392
1393config DEBUG_SPINLOCK
1394	bool "Spinlock and rw-lock debugging: basic checks"
1395	depends on DEBUG_KERNEL
1396	select UNINLINE_SPIN_UNLOCK
1397	help
1398	  Say Y here and build SMP to catch missing spinlock initialization
1399	  and certain other kinds of spinlock errors commonly made.  This is
1400	  best used in conjunction with the NMI watchdog so that spinlock
1401	  deadlocks are also debuggable.
1402
1403config DEBUG_MUTEXES
1404	bool "Mutex debugging: basic checks"
1405	depends on DEBUG_KERNEL && !PREEMPT_RT
1406	help
1407	 This feature allows mutex semantics violations to be detected and
1408	 reported.
1409
1410config DEBUG_WW_MUTEX_SLOWPATH
1411	bool "Wait/wound mutex debugging: Slowpath testing"
1412	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1413	select DEBUG_LOCK_ALLOC
1414	select DEBUG_SPINLOCK
1415	select DEBUG_MUTEXES if !PREEMPT_RT
1416	select DEBUG_RT_MUTEXES if PREEMPT_RT
1417	help
1418	 This feature enables slowpath testing for w/w mutex users by
1419	 injecting additional -EDEADLK wound/backoff cases. Together with
1420	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1421	 will test all possible w/w mutex interface abuse with the
1422	 exception of simply not acquiring all the required locks.
1423	 Note that this feature can introduce significant overhead, so
1424	 it really should not be enabled in a production or distro kernel,
1425	 even a debug kernel.  If you are a driver writer, enable it.  If
1426	 you are a distro, do not.
1427
1428config DEBUG_RWSEMS
1429	bool "RW Semaphore debugging: basic checks"
1430	depends on DEBUG_KERNEL && !PREEMPT_RT
1431	help
1432	  This debugging feature allows mismatched rw semaphore locks
1433	  and unlocks to be detected and reported.
1434
1435config DEBUG_LOCK_ALLOC
1436	bool "Lock debugging: detect incorrect freeing of live locks"
1437	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1438	select DEBUG_SPINLOCK
1439	select DEBUG_MUTEXES if !PREEMPT_RT
1440	select DEBUG_RT_MUTEXES if RT_MUTEXES
1441	select LOCKDEP
1442	help
1443	 This feature will check whether any held lock (spinlock, rwlock,
1444	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1445	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1446	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1447	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1448	 held during task exit.
1449
1450config LOCKDEP
1451	bool
1452	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1453	select STACKTRACE
1454	select KALLSYMS
1455	select KALLSYMS_ALL
1456
1457config LOCKDEP_SMALL
1458	bool
1459
1460config LOCKDEP_BITS
1461	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1462	depends on LOCKDEP && !LOCKDEP_SMALL
1463	range 10 30
1464	default 15
1465	help
1466	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1467
1468config LOCKDEP_CHAINS_BITS
1469	int "Bitsize for MAX_LOCKDEP_CHAINS"
1470	depends on LOCKDEP && !LOCKDEP_SMALL
1471	range 10 30
1472	default 16
1473	help
1474	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1475
1476config LOCKDEP_STACK_TRACE_BITS
1477	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1478	depends on LOCKDEP && !LOCKDEP_SMALL
1479	range 10 30
1480	default 19
1481	help
1482	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1483
1484config LOCKDEP_STACK_TRACE_HASH_BITS
1485	int "Bitsize for STACK_TRACE_HASH_SIZE"
1486	depends on LOCKDEP && !LOCKDEP_SMALL
1487	range 10 30
1488	default 14
1489	help
1490	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1491
1492config LOCKDEP_CIRCULAR_QUEUE_BITS
1493	int "Bitsize for elements in circular_queue struct"
1494	depends on LOCKDEP
1495	range 10 30
1496	default 12
1497	help
1498	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1499
1500config DEBUG_LOCKDEP
1501	bool "Lock dependency engine debugging"
1502	depends on DEBUG_KERNEL && LOCKDEP
1503	select DEBUG_IRQFLAGS
1504	help
1505	  If you say Y here, the lock dependency engine will do
1506	  additional runtime checks to debug itself, at the price
1507	  of more runtime overhead.
1508
1509config DEBUG_ATOMIC_SLEEP
1510	bool "Sleep inside atomic section checking"
1511	select PREEMPT_COUNT
1512	depends on DEBUG_KERNEL
1513	depends on !ARCH_NO_PREEMPT
1514	help
1515	  If you say Y here, various routines which may sleep will become very
1516	  noisy if they are called inside atomic sections: when a spinlock is
1517	  held, inside an rcu read side critical section, inside preempt disabled
1518	  sections, inside an interrupt, etc...
1519
1520config DEBUG_LOCKING_API_SELFTESTS
1521	bool "Locking API boot-time self-tests"
1522	depends on DEBUG_KERNEL
1523	help
1524	  Say Y here if you want the kernel to run a short self-test during
1525	  bootup. The self-test checks whether common types of locking bugs
1526	  are detected by debugging mechanisms or not. (if you disable
1527	  lock debugging then those bugs won't be detected of course.)
1528	  The following locking APIs are covered: spinlocks, rwlocks,
1529	  mutexes and rwsems.
1530
1531config LOCK_TORTURE_TEST
1532	tristate "torture tests for locking"
1533	depends on DEBUG_KERNEL
1534	select TORTURE_TEST
1535	help
1536	  This option provides a kernel module that runs torture tests
1537	  on kernel locking primitives.  The kernel module may be built
1538	  after the fact on the running kernel to be tested, if desired.
1539
1540	  Say Y here if you want kernel locking-primitive torture tests
1541	  to be built into the kernel.
1542	  Say M if you want these torture tests to build as a module.
1543	  Say N if you are unsure.
1544
1545config WW_MUTEX_SELFTEST
1546	tristate "Wait/wound mutex selftests"
1547	help
1548	  This option provides a kernel module that runs tests on the
1549	  on the struct ww_mutex locking API.
1550
1551	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1552	  with this test harness.
1553
1554	  Say M if you want these self tests to build as a module.
1555	  Say N if you are unsure.
1556
1557config SCF_TORTURE_TEST
1558	tristate "torture tests for smp_call_function*()"
1559	depends on DEBUG_KERNEL
1560	select TORTURE_TEST
1561	help
1562	  This option provides a kernel module that runs torture tests
1563	  on the smp_call_function() family of primitives.  The kernel
1564	  module may be built after the fact on the running kernel to
1565	  be tested, if desired.
1566
1567config CSD_LOCK_WAIT_DEBUG
1568	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1569	depends on DEBUG_KERNEL
1570	depends on 64BIT
1571	default n
1572	help
1573	  This option enables debug prints when CPUs are slow to respond
1574	  to the smp_call_function*() IPI wrappers.  These debug prints
1575	  include the IPI handler function currently executing (if any)
1576	  and relevant stack traces.
1577
1578config CSD_LOCK_WAIT_DEBUG_DEFAULT
1579	bool "Default csd_lock_wait() debugging on at boot time"
1580	depends on CSD_LOCK_WAIT_DEBUG
1581	depends on 64BIT
1582	default n
1583	help
1584	  This option causes the csdlock_debug= kernel boot parameter to
1585	  default to 1 (basic debugging) instead of 0 (no debugging).
1586
1587endmenu # lock debugging
1588
1589config TRACE_IRQFLAGS
1590	depends on TRACE_IRQFLAGS_SUPPORT
1591	bool
1592	help
1593	  Enables hooks to interrupt enabling and disabling for
1594	  either tracing or lock debugging.
1595
1596config TRACE_IRQFLAGS_NMI
1597	def_bool y
1598	depends on TRACE_IRQFLAGS
1599	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1600
1601config NMI_CHECK_CPU
1602	bool "Debugging for CPUs failing to respond to backtrace requests"
1603	depends on DEBUG_KERNEL
1604	depends on X86
1605	default n
1606	help
1607	  Enables debug prints when a CPU fails to respond to a given
1608	  backtrace NMI.  These prints provide some reasons why a CPU
1609	  might legitimately be failing to respond, for example, if it
1610	  is offline of if ignore_nmis is set.
1611
1612config DEBUG_IRQFLAGS
1613	bool "Debug IRQ flag manipulation"
1614	help
1615	  Enables checks for potentially unsafe enabling or disabling of
1616	  interrupts, such as calling raw_local_irq_restore() when interrupts
1617	  are enabled.
1618
1619config STACKTRACE
1620	bool "Stack backtrace support"
1621	depends on STACKTRACE_SUPPORT
1622	help
1623	  This option causes the kernel to create a /proc/pid/stack for
1624	  every process, showing its current stack trace.
1625	  It is also used by various kernel debugging features that require
1626	  stack trace generation.
1627
1628config WARN_ALL_UNSEEDED_RANDOM
1629	bool "Warn for all uses of unseeded randomness"
1630	default n
1631	help
1632	  Some parts of the kernel contain bugs relating to their use of
1633	  cryptographically secure random numbers before it's actually possible
1634	  to generate those numbers securely. This setting ensures that these
1635	  flaws don't go unnoticed, by enabling a message, should this ever
1636	  occur. This will allow people with obscure setups to know when things
1637	  are going wrong, so that they might contact developers about fixing
1638	  it.
1639
1640	  Unfortunately, on some models of some architectures getting
1641	  a fully seeded CRNG is extremely difficult, and so this can
1642	  result in dmesg getting spammed for a surprisingly long
1643	  time.  This is really bad from a security perspective, and
1644	  so architecture maintainers really need to do what they can
1645	  to get the CRNG seeded sooner after the system is booted.
1646	  However, since users cannot do anything actionable to
1647	  address this, by default this option is disabled.
1648
1649	  Say Y here if you want to receive warnings for all uses of
1650	  unseeded randomness.  This will be of use primarily for
1651	  those developers interested in improving the security of
1652	  Linux kernels running on their architecture (or
1653	  subarchitecture).
1654
1655config DEBUG_KOBJECT
1656	bool "kobject debugging"
1657	depends on DEBUG_KERNEL
1658	help
1659	  If you say Y here, some extra kobject debugging messages will be sent
1660	  to the syslog.
1661
1662config DEBUG_KOBJECT_RELEASE
1663	bool "kobject release debugging"
1664	depends on DEBUG_OBJECTS_TIMERS
1665	help
1666	  kobjects are reference counted objects.  This means that their
1667	  last reference count put is not predictable, and the kobject can
1668	  live on past the point at which a driver decides to drop its
1669	  initial reference to the kobject gained on allocation.  An
1670	  example of this would be a struct device which has just been
1671	  unregistered.
1672
1673	  However, some buggy drivers assume that after such an operation,
1674	  the memory backing the kobject can be immediately freed.  This
1675	  goes completely against the principles of a refcounted object.
1676
1677	  If you say Y here, the kernel will delay the release of kobjects
1678	  on the last reference count to improve the visibility of this
1679	  kind of kobject release bug.
1680
1681config HAVE_DEBUG_BUGVERBOSE
1682	bool
1683
1684menu "Debug kernel data structures"
1685
1686config DEBUG_LIST
1687	bool "Debug linked list manipulation"
1688	depends on DEBUG_KERNEL
1689	select LIST_HARDENED
1690	help
1691	  Enable this to turn on extended checks in the linked-list walking
1692	  routines.
1693
1694	  This option trades better quality error reports for performance, and
1695	  is more suitable for kernel debugging. If you care about performance,
1696	  you should only enable CONFIG_LIST_HARDENED instead.
1697
1698	  If unsure, say N.
1699
1700config DEBUG_PLIST
1701	bool "Debug priority linked list manipulation"
1702	depends on DEBUG_KERNEL
1703	help
1704	  Enable this to turn on extended checks in the priority-ordered
1705	  linked-list (plist) walking routines.  This checks the entire
1706	  list multiple times during each manipulation.
1707
1708	  If unsure, say N.
1709
1710config DEBUG_SG
1711	bool "Debug SG table operations"
1712	depends on DEBUG_KERNEL
1713	help
1714	  Enable this to turn on checks on scatter-gather tables. This can
1715	  help find problems with drivers that do not properly initialize
1716	  their sg tables.
1717
1718	  If unsure, say N.
1719
1720config DEBUG_NOTIFIERS
1721	bool "Debug notifier call chains"
1722	depends on DEBUG_KERNEL
1723	help
1724	  Enable this to turn on sanity checking for notifier call chains.
1725	  This is most useful for kernel developers to make sure that
1726	  modules properly unregister themselves from notifier chains.
1727	  This is a relatively cheap check but if you care about maximum
1728	  performance, say N.
1729
1730config DEBUG_CLOSURES
1731	bool "Debug closures (bcache async widgits)"
1732	depends on CLOSURES
1733	select DEBUG_FS
1734	help
1735	  Keeps all active closures in a linked list and provides a debugfs
1736	  interface to list them, which makes it possible to see asynchronous
1737	  operations that get stuck.
1738
1739config DEBUG_MAPLE_TREE
1740	bool "Debug maple trees"
1741	depends on DEBUG_KERNEL
1742	help
1743	  Enable maple tree debugging information and extra validations.
1744
1745	  If unsure, say N.
1746
1747endmenu
1748
1749source "kernel/rcu/Kconfig.debug"
1750
1751config DEBUG_WQ_FORCE_RR_CPU
1752	bool "Force round-robin CPU selection for unbound work items"
1753	depends on DEBUG_KERNEL
1754	default n
1755	help
1756	  Workqueue used to implicitly guarantee that work items queued
1757	  without explicit CPU specified are put on the local CPU.  This
1758	  guarantee is no longer true and while local CPU is still
1759	  preferred work items may be put on foreign CPUs.  Kernel
1760	  parameter "workqueue.debug_force_rr_cpu" is added to force
1761	  round-robin CPU selection to flush out usages which depend on the
1762	  now broken guarantee.  This config option enables the debug
1763	  feature by default.  When enabled, memory and cache locality will
1764	  be impacted.
1765
1766config CPU_HOTPLUG_STATE_CONTROL
1767	bool "Enable CPU hotplug state control"
1768	depends on DEBUG_KERNEL
1769	depends on HOTPLUG_CPU
1770	default n
1771	help
1772	  Allows to write steps between "offline" and "online" to the CPUs
1773	  sysfs target file so states can be stepped granular. This is a debug
1774	  option for now as the hotplug machinery cannot be stopped and
1775	  restarted at arbitrary points yet.
1776
1777	  Say N if your are unsure.
1778
1779config LATENCYTOP
1780	bool "Latency measuring infrastructure"
1781	depends on DEBUG_KERNEL
1782	depends on STACKTRACE_SUPPORT
1783	depends on PROC_FS
1784	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1785	select KALLSYMS
1786	select KALLSYMS_ALL
1787	select STACKTRACE
1788	select SCHEDSTATS
1789	help
1790	  Enable this option if you want to use the LatencyTOP tool
1791	  to find out which userspace is blocking on what kernel operations.
1792
1793config DEBUG_CGROUP_REF
1794	bool "Disable inlining of cgroup css reference count functions"
1795	depends on DEBUG_KERNEL
1796	depends on CGROUPS
1797	depends on KPROBES
1798	default n
1799	help
1800	  Force cgroup css reference count functions to not be inlined so
1801	  that they can be kprobed for debugging.
1802
1803source "kernel/trace/Kconfig"
1804
1805config PROVIDE_OHCI1394_DMA_INIT
1806	bool "Remote debugging over FireWire early on boot"
1807	depends on PCI && X86
1808	help
1809	  If you want to debug problems which hang or crash the kernel early
1810	  on boot and the crashing machine has a FireWire port, you can use
1811	  this feature to remotely access the memory of the crashed machine
1812	  over FireWire. This employs remote DMA as part of the OHCI1394
1813	  specification which is now the standard for FireWire controllers.
1814
1815	  With remote DMA, you can monitor the printk buffer remotely using
1816	  firescope and access all memory below 4GB using fireproxy from gdb.
1817	  Even controlling a kernel debugger is possible using remote DMA.
1818
1819	  Usage:
1820
1821	  If ohci1394_dma=early is used as boot parameter, it will initialize
1822	  all OHCI1394 controllers which are found in the PCI config space.
1823
1824	  As all changes to the FireWire bus such as enabling and disabling
1825	  devices cause a bus reset and thereby disable remote DMA for all
1826	  devices, be sure to have the cable plugged and FireWire enabled on
1827	  the debugging host before booting the debug target for debugging.
1828
1829	  This code (~1k) is freed after boot. By then, the firewire stack
1830	  in charge of the OHCI-1394 controllers should be used instead.
1831
1832	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1833
1834source "samples/Kconfig"
1835
1836config ARCH_HAS_DEVMEM_IS_ALLOWED
1837	bool
1838
1839config STRICT_DEVMEM
1840	bool "Filter access to /dev/mem"
1841	depends on MMU && DEVMEM
1842	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1843	default y if PPC || X86 || ARM64
1844	help
1845	  If this option is disabled, you allow userspace (root) access to all
1846	  of memory, including kernel and userspace memory. Accidental
1847	  access to this is obviously disastrous, but specific access can
1848	  be used by people debugging the kernel. Note that with PAT support
1849	  enabled, even in this case there are restrictions on /dev/mem
1850	  use due to the cache aliasing requirements.
1851
1852	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1853	  file only allows userspace access to PCI space and the BIOS code and
1854	  data regions.  This is sufficient for dosemu and X and all common
1855	  users of /dev/mem.
1856
1857	  If in doubt, say Y.
1858
1859config IO_STRICT_DEVMEM
1860	bool "Filter I/O access to /dev/mem"
1861	depends on STRICT_DEVMEM
1862	help
1863	  If this option is disabled, you allow userspace (root) access to all
1864	  io-memory regardless of whether a driver is actively using that
1865	  range.  Accidental access to this is obviously disastrous, but
1866	  specific access can be used by people debugging kernel drivers.
1867
1868	  If this option is switched on, the /dev/mem file only allows
1869	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1870	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1871	  if the driver using a given range cannot be disabled.
1872
1873	  If in doubt, say Y.
1874
1875menu "$(SRCARCH) Debugging"
1876
1877source "arch/$(SRCARCH)/Kconfig.debug"
1878
1879endmenu
1880
1881menu "Kernel Testing and Coverage"
1882
1883source "lib/kunit/Kconfig"
1884
1885config NOTIFIER_ERROR_INJECTION
1886	tristate "Notifier error injection"
1887	depends on DEBUG_KERNEL
1888	select DEBUG_FS
1889	help
1890	  This option provides the ability to inject artificial errors to
1891	  specified notifier chain callbacks. It is useful to test the error
1892	  handling of notifier call chain failures.
1893
1894	  Say N if unsure.
1895
1896config PM_NOTIFIER_ERROR_INJECT
1897	tristate "PM notifier error injection module"
1898	depends on PM && NOTIFIER_ERROR_INJECTION
1899	default m if PM_DEBUG
1900	help
1901	  This option provides the ability to inject artificial errors to
1902	  PM notifier chain callbacks.  It is controlled through debugfs
1903	  interface /sys/kernel/debug/notifier-error-inject/pm
1904
1905	  If the notifier call chain should be failed with some events
1906	  notified, write the error code to "actions/<notifier event>/error".
1907
1908	  Example: Inject PM suspend error (-12 = -ENOMEM)
1909
1910	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1911	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1912	  # echo mem > /sys/power/state
1913	  bash: echo: write error: Cannot allocate memory
1914
1915	  To compile this code as a module, choose M here: the module will
1916	  be called pm-notifier-error-inject.
1917
1918	  If unsure, say N.
1919
1920config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1921	tristate "OF reconfig notifier error injection module"
1922	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1923	help
1924	  This option provides the ability to inject artificial errors to
1925	  OF reconfig notifier chain callbacks.  It is controlled
1926	  through debugfs interface under
1927	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1928
1929	  If the notifier call chain should be failed with some events
1930	  notified, write the error code to "actions/<notifier event>/error".
1931
1932	  To compile this code as a module, choose M here: the module will
1933	  be called of-reconfig-notifier-error-inject.
1934
1935	  If unsure, say N.
1936
1937config NETDEV_NOTIFIER_ERROR_INJECT
1938	tristate "Netdev notifier error injection module"
1939	depends on NET && NOTIFIER_ERROR_INJECTION
1940	help
1941	  This option provides the ability to inject artificial errors to
1942	  netdevice notifier chain callbacks.  It is controlled through debugfs
1943	  interface /sys/kernel/debug/notifier-error-inject/netdev
1944
1945	  If the notifier call chain should be failed with some events
1946	  notified, write the error code to "actions/<notifier event>/error".
1947
1948	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1949
1950	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1951	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1952	  # ip link set eth0 mtu 1024
1953	  RTNETLINK answers: Invalid argument
1954
1955	  To compile this code as a module, choose M here: the module will
1956	  be called netdev-notifier-error-inject.
1957
1958	  If unsure, say N.
1959
1960config FUNCTION_ERROR_INJECTION
1961	bool "Fault-injections of functions"
1962	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1963	help
1964	  Add fault injections into various functions that are annotated with
1965	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1966	  value of these functions. This is useful to test error paths of code.
1967
1968	  If unsure, say N
1969
1970config FAULT_INJECTION
1971	bool "Fault-injection framework"
1972	depends on DEBUG_KERNEL
1973	help
1974	  Provide fault-injection framework.
1975	  For more details, see Documentation/fault-injection/.
1976
1977config FAILSLAB
1978	bool "Fault-injection capability for kmalloc"
1979	depends on FAULT_INJECTION
1980	help
1981	  Provide fault-injection capability for kmalloc.
1982
1983config FAIL_PAGE_ALLOC
1984	bool "Fault-injection capability for alloc_pages()"
1985	depends on FAULT_INJECTION
1986	help
1987	  Provide fault-injection capability for alloc_pages().
1988
1989config FAULT_INJECTION_USERCOPY
1990	bool "Fault injection capability for usercopy functions"
1991	depends on FAULT_INJECTION
1992	help
1993	  Provides fault-injection capability to inject failures
1994	  in usercopy functions (copy_from_user(), get_user(), ...).
1995
1996config FAIL_MAKE_REQUEST
1997	bool "Fault-injection capability for disk IO"
1998	depends on FAULT_INJECTION && BLOCK
1999	help
2000	  Provide fault-injection capability for disk IO.
2001
2002config FAIL_IO_TIMEOUT
2003	bool "Fault-injection capability for faking disk interrupts"
2004	depends on FAULT_INJECTION && BLOCK
2005	help
2006	  Provide fault-injection capability on end IO handling. This
2007	  will make the block layer "forget" an interrupt as configured,
2008	  thus exercising the error handling.
2009
2010	  Only works with drivers that use the generic timeout handling,
2011	  for others it won't do anything.
2012
2013config FAIL_FUTEX
2014	bool "Fault-injection capability for futexes"
2015	select DEBUG_FS
2016	depends on FAULT_INJECTION && FUTEX
2017	help
2018	  Provide fault-injection capability for futexes.
2019
2020config FAULT_INJECTION_DEBUG_FS
2021	bool "Debugfs entries for fault-injection capabilities"
2022	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2023	help
2024	  Enable configuration of fault-injection capabilities via debugfs.
2025
2026config FAIL_FUNCTION
2027	bool "Fault-injection capability for functions"
2028	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2029	help
2030	  Provide function-based fault-injection capability.
2031	  This will allow you to override a specific function with a return
2032	  with given return value. As a result, function caller will see
2033	  an error value and have to handle it. This is useful to test the
2034	  error handling in various subsystems.
2035
2036config FAIL_MMC_REQUEST
2037	bool "Fault-injection capability for MMC IO"
2038	depends on FAULT_INJECTION_DEBUG_FS && MMC
2039	help
2040	  Provide fault-injection capability for MMC IO.
2041	  This will make the mmc core return data errors. This is
2042	  useful to test the error handling in the mmc block device
2043	  and to test how the mmc host driver handles retries from
2044	  the block device.
2045
2046config FAIL_SUNRPC
2047	bool "Fault-injection capability for SunRPC"
2048	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2049	help
2050	  Provide fault-injection capability for SunRPC and
2051	  its consumers.
2052
2053config FAULT_INJECTION_CONFIGFS
2054	bool "Configfs interface for fault-injection capabilities"
2055	depends on FAULT_INJECTION
2056	select CONFIGFS_FS
2057	help
2058	  This option allows configfs-based drivers to dynamically configure
2059	  fault-injection via configfs.  Each parameter for driver-specific
2060	  fault-injection can be made visible as a configfs attribute in a
2061	  configfs group.
2062
2063
2064config FAULT_INJECTION_STACKTRACE_FILTER
2065	bool "stacktrace filter for fault-injection capabilities"
2066	depends on FAULT_INJECTION
2067	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2068	select STACKTRACE
2069	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2070	help
2071	  Provide stacktrace filter for fault-injection capabilities
2072
2073config ARCH_HAS_KCOV
2074	bool
2075	help
2076	  An architecture should select this when it can successfully
2077	  build and run with CONFIG_KCOV. This typically requires
2078	  disabling instrumentation for some early boot code.
2079
2080config CC_HAS_SANCOV_TRACE_PC
2081	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2082
2083
2084config KCOV
2085	bool "Code coverage for fuzzing"
2086	depends on ARCH_HAS_KCOV
2087	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2088	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2089		   GCC_VERSION >= 120000 || CC_IS_CLANG
2090	select DEBUG_FS
2091	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2092	select OBJTOOL if HAVE_NOINSTR_HACK
2093	help
2094	  KCOV exposes kernel code coverage information in a form suitable
2095	  for coverage-guided fuzzing (randomized testing).
2096
2097	  For more details, see Documentation/dev-tools/kcov.rst.
2098
2099config KCOV_ENABLE_COMPARISONS
2100	bool "Enable comparison operands collection by KCOV"
2101	depends on KCOV
2102	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2103	help
2104	  KCOV also exposes operands of every comparison in the instrumented
2105	  code along with operand sizes and PCs of the comparison instructions.
2106	  These operands can be used by fuzzing engines to improve the quality
2107	  of fuzzing coverage.
2108
2109config KCOV_INSTRUMENT_ALL
2110	bool "Instrument all code by default"
2111	depends on KCOV
2112	default y
2113	help
2114	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2115	  then you will want to instrument the whole kernel and you should
2116	  say y here. If you are doing more targeted fuzzing (like e.g.
2117	  filesystem fuzzing with AFL) then you will want to enable coverage
2118	  for more specific subsets of files, and should say n here.
2119
2120config KCOV_IRQ_AREA_SIZE
2121	hex "Size of interrupt coverage collection area in words"
2122	depends on KCOV
2123	default 0x40000
2124	help
2125	  KCOV uses preallocated per-cpu areas to collect coverage from
2126	  soft interrupts. This specifies the size of those areas in the
2127	  number of unsigned long words.
2128
2129menuconfig RUNTIME_TESTING_MENU
2130	bool "Runtime Testing"
2131	default y
2132
2133if RUNTIME_TESTING_MENU
2134
2135config TEST_DHRY
2136	tristate "Dhrystone benchmark test"
2137	help
2138	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2139	  calculates the number of Dhrystones per second, and the number of
2140	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2141	  by 1757 (the number of Dhrystones per second obtained on the VAX
2142	  11/780, nominally a 1 MIPS machine).
2143
2144	  To run the benchmark, it needs to be enabled explicitly, either from
2145	  the kernel command line (when built-in), or from userspace (when
2146	  built-in or modular).
2147
2148	  Run once during kernel boot:
2149
2150	      test_dhry.run
2151
2152	  Set number of iterations from kernel command line:
2153
2154	      test_dhry.iterations=<n>
2155
2156	  Set number of iterations from userspace:
2157
2158	      echo <n> > /sys/module/test_dhry/parameters/iterations
2159
2160	  Trigger manual run from userspace:
2161
2162	      echo y > /sys/module/test_dhry/parameters/run
2163
2164	  If the number of iterations is <= 0, the test will devise a suitable
2165	  number of iterations (test runs for at least 2s) automatically.
2166	  This process takes ca. 4s.
2167
2168	  If unsure, say N.
2169
2170config LKDTM
2171	tristate "Linux Kernel Dump Test Tool Module"
2172	depends on DEBUG_FS
2173	help
2174	This module enables testing of the different dumping mechanisms by
2175	inducing system failures at predefined crash points.
2176	If you don't need it: say N
2177	Choose M here to compile this code as a module. The module will be
2178	called lkdtm.
2179
2180	Documentation on how to use the module can be found in
2181	Documentation/fault-injection/provoke-crashes.rst
2182
2183config CPUMASK_KUNIT_TEST
2184	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2185	depends on KUNIT
2186	default KUNIT_ALL_TESTS
2187	help
2188	  Enable to turn on cpumask tests, running at boot or module load time.
2189
2190	  For more information on KUnit and unit tests in general, please refer
2191	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2192
2193	  If unsure, say N.
2194
2195config TEST_LIST_SORT
2196	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2197	depends on KUNIT
2198	default KUNIT_ALL_TESTS
2199	help
2200	  Enable this to turn on 'list_sort()' function test. This test is
2201	  executed only once during system boot (so affects only boot time),
2202	  or at module load time.
2203
2204	  If unsure, say N.
2205
2206config TEST_MIN_HEAP
2207	tristate "Min heap test"
2208	depends on DEBUG_KERNEL || m
2209	help
2210	  Enable this to turn on min heap function tests. This test is
2211	  executed only once during system boot (so affects only boot time),
2212	  or at module load time.
2213
2214	  If unsure, say N.
2215
2216config TEST_SORT
2217	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2218	depends on KUNIT
2219	default KUNIT_ALL_TESTS
2220	help
2221	  This option enables the self-test function of 'sort()' at boot,
2222	  or at module load time.
2223
2224	  If unsure, say N.
2225
2226config TEST_DIV64
2227	tristate "64bit/32bit division and modulo test"
2228	depends on DEBUG_KERNEL || m
2229	help
2230	  Enable this to turn on 'do_div()' function test. This test is
2231	  executed only once during system boot (so affects only boot time),
2232	  or at module load time.
2233
2234	  If unsure, say N.
2235
2236config TEST_IOV_ITER
2237	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2238	depends on KUNIT
2239	depends on MMU
2240	default KUNIT_ALL_TESTS
2241	help
2242	  Enable this to turn on testing of the operation of the I/O iterator
2243	  (iov_iter). This test is executed only once during system boot (so
2244	  affects only boot time), or at module load time.
2245
2246	  If unsure, say N.
2247
2248config KPROBES_SANITY_TEST
2249	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2250	depends on DEBUG_KERNEL
2251	depends on KPROBES
2252	depends on KUNIT
2253	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2254	default KUNIT_ALL_TESTS
2255	help
2256	  This option provides for testing basic kprobes functionality on
2257	  boot. Samples of kprobe and kretprobe are inserted and
2258	  verified for functionality.
2259
2260	  Say N if you are unsure.
2261
2262config FPROBE_SANITY_TEST
2263	bool "Self test for fprobe"
2264	depends on DEBUG_KERNEL
2265	depends on FPROBE
2266	depends on KUNIT=y
2267	help
2268	  This option will enable testing the fprobe when the system boot.
2269	  A series of tests are made to verify that the fprobe is functioning
2270	  properly.
2271
2272	  Say N if you are unsure.
2273
2274config BACKTRACE_SELF_TEST
2275	tristate "Self test for the backtrace code"
2276	depends on DEBUG_KERNEL
2277	help
2278	  This option provides a kernel module that can be used to test
2279	  the kernel stack backtrace code. This option is not useful
2280	  for distributions or general kernels, but only for kernel
2281	  developers working on architecture code.
2282
2283	  Note that if you want to also test saved backtraces, you will
2284	  have to enable STACKTRACE as well.
2285
2286	  Say N if you are unsure.
2287
2288config TEST_REF_TRACKER
2289	tristate "Self test for reference tracker"
2290	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2291	select REF_TRACKER
2292	help
2293	  This option provides a kernel module performing tests
2294	  using reference tracker infrastructure.
2295
2296	  Say N if you are unsure.
2297
2298config RBTREE_TEST
2299	tristate "Red-Black tree test"
2300	depends on DEBUG_KERNEL
2301	help
2302	  A benchmark measuring the performance of the rbtree library.
2303	  Also includes rbtree invariant checks.
2304
2305config REED_SOLOMON_TEST
2306	tristate "Reed-Solomon library test"
2307	depends on DEBUG_KERNEL || m
2308	select REED_SOLOMON
2309	select REED_SOLOMON_ENC16
2310	select REED_SOLOMON_DEC16
2311	help
2312	  This option enables the self-test function of rslib at boot,
2313	  or at module load time.
2314
2315	  If unsure, say N.
2316
2317config INTERVAL_TREE_TEST
2318	tristate "Interval tree test"
2319	depends on DEBUG_KERNEL
2320	select INTERVAL_TREE
2321	help
2322	  A benchmark measuring the performance of the interval tree library
2323
2324config PERCPU_TEST
2325	tristate "Per cpu operations test"
2326	depends on m && DEBUG_KERNEL
2327	help
2328	  Enable this option to build test module which validates per-cpu
2329	  operations.
2330
2331	  If unsure, say N.
2332
2333config ATOMIC64_SELFTEST
2334	tristate "Perform an atomic64_t self-test"
2335	help
2336	  Enable this option to test the atomic64_t functions at boot or
2337	  at module load time.
2338
2339	  If unsure, say N.
2340
2341config ASYNC_RAID6_TEST
2342	tristate "Self test for hardware accelerated raid6 recovery"
2343	depends on ASYNC_RAID6_RECOV
2344	select ASYNC_MEMCPY
2345	help
2346	  This is a one-shot self test that permutes through the
2347	  recovery of all the possible two disk failure scenarios for a
2348	  N-disk array.  Recovery is performed with the asynchronous
2349	  raid6 recovery routines, and will optionally use an offload
2350	  engine if one is available.
2351
2352	  If unsure, say N.
2353
2354config TEST_HEXDUMP
2355	tristate "Test functions located in the hexdump module at runtime"
2356
2357config STRING_KUNIT_TEST
2358	tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
2359	depends on KUNIT
2360	default KUNIT_ALL_TESTS
2361
2362config STRING_HELPERS_KUNIT_TEST
2363	tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
2364	depends on KUNIT
2365	default KUNIT_ALL_TESTS
2366
2367config TEST_KSTRTOX
2368	tristate "Test kstrto*() family of functions at runtime"
2369
2370config TEST_PRINTF
2371	tristate "Test printf() family of functions at runtime"
2372
2373config TEST_SCANF
2374	tristate "Test scanf() family of functions at runtime"
2375
2376config TEST_BITMAP
2377	tristate "Test bitmap_*() family of functions at runtime"
2378	help
2379	  Enable this option to test the bitmap functions at boot.
2380
2381	  If unsure, say N.
2382
2383config TEST_UUID
2384	tristate "Test functions located in the uuid module at runtime"
2385
2386config TEST_XARRAY
2387	tristate "Test the XArray code at runtime"
2388
2389config TEST_MAPLE_TREE
2390	tristate "Test the Maple Tree code at runtime or module load"
2391	help
2392	  Enable this option to test the maple tree code functions at boot, or
2393	  when the module is loaded. Enable "Debug Maple Trees" will enable
2394	  more verbose output on failures.
2395
2396	  If unsure, say N.
2397
2398config TEST_RHASHTABLE
2399	tristate "Perform selftest on resizable hash table"
2400	help
2401	  Enable this option to test the rhashtable functions at boot.
2402
2403	  If unsure, say N.
2404
2405config TEST_IDA
2406	tristate "Perform selftest on IDA functions"
2407
2408config TEST_PARMAN
2409	tristate "Perform selftest on priority array manager"
2410	depends on PARMAN
2411	help
2412	  Enable this option to test priority array manager on boot
2413	  (or module load).
2414
2415	  If unsure, say N.
2416
2417config TEST_IRQ_TIMINGS
2418	bool "IRQ timings selftest"
2419	depends on IRQ_TIMINGS
2420	help
2421	  Enable this option to test the irq timings code on boot.
2422
2423	  If unsure, say N.
2424
2425config TEST_LKM
2426	tristate "Test module loading with 'hello world' module"
2427	depends on m
2428	help
2429	  This builds the "test_module" module that emits "Hello, world"
2430	  on printk when loaded. It is designed to be used for basic
2431	  evaluation of the module loading subsystem (for example when
2432	  validating module verification). It lacks any extra dependencies,
2433	  and will not normally be loaded by the system unless explicitly
2434	  requested by name.
2435
2436	  If unsure, say N.
2437
2438config TEST_BITOPS
2439	tristate "Test module for compilation of bitops operations"
2440	depends on m
2441	help
2442	  This builds the "test_bitops" module that is much like the
2443	  TEST_LKM module except that it does a basic exercise of the
2444	  set/clear_bit macros and get_count_order/long to make sure there are
2445	  no compiler warnings from C=1 sparse checker or -Wextra
2446	  compilations. It has no dependencies and doesn't run or load unless
2447	  explicitly requested by name.  for example: modprobe test_bitops.
2448
2449	  If unsure, say N.
2450
2451config TEST_VMALLOC
2452	tristate "Test module for stress/performance analysis of vmalloc allocator"
2453	default n
2454       depends on MMU
2455	depends on m
2456	help
2457	  This builds the "test_vmalloc" module that should be used for
2458	  stress and performance analysis. So, any new change for vmalloc
2459	  subsystem can be evaluated from performance and stability point
2460	  of view.
2461
2462	  If unsure, say N.
2463
2464config TEST_USER_COPY
2465	tristate "Test user/kernel boundary protections"
2466	depends on m
2467	help
2468	  This builds the "test_user_copy" module that runs sanity checks
2469	  on the copy_to/from_user infrastructure, making sure basic
2470	  user/kernel boundary testing is working. If it fails to load,
2471	  a regression has been detected in the user/kernel memory boundary
2472	  protections.
2473
2474	  If unsure, say N.
2475
2476config TEST_BPF
2477	tristate "Test BPF filter functionality"
2478	depends on m && NET
2479	help
2480	  This builds the "test_bpf" module that runs various test vectors
2481	  against the BPF interpreter or BPF JIT compiler depending on the
2482	  current setting. This is in particular useful for BPF JIT compiler
2483	  development, but also to run regression tests against changes in
2484	  the interpreter code. It also enables test stubs for eBPF maps and
2485	  verifier used by user space verifier testsuite.
2486
2487	  If unsure, say N.
2488
2489config TEST_BLACKHOLE_DEV
2490	tristate "Test blackhole netdev functionality"
2491	depends on m && NET
2492	help
2493	  This builds the "test_blackhole_dev" module that validates the
2494	  data path through this blackhole netdev.
2495
2496	  If unsure, say N.
2497
2498config FIND_BIT_BENCHMARK
2499	tristate "Test find_bit functions"
2500	help
2501	  This builds the "test_find_bit" module that measure find_*_bit()
2502	  functions performance.
2503
2504	  If unsure, say N.
2505
2506config TEST_FIRMWARE
2507	tristate "Test firmware loading via userspace interface"
2508	depends on FW_LOADER
2509	help
2510	  This builds the "test_firmware" module that creates a userspace
2511	  interface for testing firmware loading. This can be used to
2512	  control the triggering of firmware loading without needing an
2513	  actual firmware-using device. The contents can be rechecked by
2514	  userspace.
2515
2516	  If unsure, say N.
2517
2518config TEST_SYSCTL
2519	tristate "sysctl test driver"
2520	depends on PROC_SYSCTL
2521	help
2522	  This builds the "test_sysctl" module. This driver enables to test the
2523	  proc sysctl interfaces available to drivers safely without affecting
2524	  production knobs which might alter system functionality.
2525
2526	  If unsure, say N.
2527
2528config BITFIELD_KUNIT
2529	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2530	depends on KUNIT
2531	default KUNIT_ALL_TESTS
2532	help
2533	  Enable this option to test the bitfield functions at boot.
2534
2535	  KUnit tests run during boot and output the results to the debug log
2536	  in TAP format (http://testanything.org/). Only useful for kernel devs
2537	  running the KUnit test harness, and not intended for inclusion into a
2538	  production build.
2539
2540	  For more information on KUnit and unit tests in general please refer
2541	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2542
2543	  If unsure, say N.
2544
2545config CHECKSUM_KUNIT
2546	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2547	depends on KUNIT
2548	default KUNIT_ALL_TESTS
2549	help
2550	  Enable this option to test the checksum functions at boot.
2551
2552	  KUnit tests run during boot and output the results to the debug log
2553	  in TAP format (http://testanything.org/). Only useful for kernel devs
2554	  running the KUnit test harness, and not intended for inclusion into a
2555	  production build.
2556
2557	  For more information on KUnit and unit tests in general please refer
2558	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2559
2560	  If unsure, say N.
2561
2562config HASH_KUNIT_TEST
2563	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2564	depends on KUNIT
2565	default KUNIT_ALL_TESTS
2566	help
2567	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2568	  integer (<linux/hash.h>) hash functions on boot.
2569
2570	  KUnit tests run during boot and output the results to the debug log
2571	  in TAP format (https://testanything.org/). Only useful for kernel devs
2572	  running the KUnit test harness, and not intended for inclusion into a
2573	  production build.
2574
2575	  For more information on KUnit and unit tests in general please refer
2576	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2577
2578	  This is intended to help people writing architecture-specific
2579	  optimized versions. If unsure, say N.
2580
2581config RESOURCE_KUNIT_TEST
2582	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2583	depends on KUNIT
2584	default KUNIT_ALL_TESTS
2585	help
2586	  This builds the resource API unit test.
2587	  Tests the logic of API provided by resource.c and ioport.h.
2588	  For more information on KUnit and unit tests in general please refer
2589	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2590
2591	  If unsure, say N.
2592
2593config SYSCTL_KUNIT_TEST
2594	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2595	depends on KUNIT
2596	default KUNIT_ALL_TESTS
2597	help
2598	  This builds the proc sysctl unit test, which runs on boot.
2599	  Tests the API contract and implementation correctness of sysctl.
2600	  For more information on KUnit and unit tests in general please refer
2601	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2602
2603	  If unsure, say N.
2604
2605config LIST_KUNIT_TEST
2606	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2607	depends on KUNIT
2608	default KUNIT_ALL_TESTS
2609	help
2610	  This builds the linked list KUnit test suite.
2611	  It tests that the API and basic functionality of the list_head type
2612	  and associated macros.
2613
2614	  KUnit tests run during boot and output the results to the debug log
2615	  in TAP format (https://testanything.org/). Only useful for kernel devs
2616	  running the KUnit test harness, and not intended for inclusion into a
2617	  production build.
2618
2619	  For more information on KUnit and unit tests in general please refer
2620	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2621
2622	  If unsure, say N.
2623
2624config HASHTABLE_KUNIT_TEST
2625	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2626	depends on KUNIT
2627	default KUNIT_ALL_TESTS
2628	help
2629	  This builds the hashtable KUnit test suite.
2630	  It tests the basic functionality of the API defined in
2631	  include/linux/hashtable.h. For more information on KUnit and
2632	  unit tests in general please refer to the KUnit documentation
2633	  in Documentation/dev-tools/kunit/.
2634
2635	  If unsure, say N.
2636
2637config LINEAR_RANGES_TEST
2638	tristate "KUnit test for linear_ranges"
2639	depends on KUNIT
2640	select LINEAR_RANGES
2641	help
2642	  This builds the linear_ranges unit test, which runs on boot.
2643	  Tests the linear_ranges logic correctness.
2644	  For more information on KUnit and unit tests in general please refer
2645	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2646
2647	  If unsure, say N.
2648
2649config CMDLINE_KUNIT_TEST
2650	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2651	depends on KUNIT
2652	default KUNIT_ALL_TESTS
2653	help
2654	  This builds the cmdline API unit test.
2655	  Tests the logic of API provided by cmdline.c.
2656	  For more information on KUnit and unit tests in general please refer
2657	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2658
2659	  If unsure, say N.
2660
2661config BITS_TEST
2662	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2663	depends on KUNIT
2664	default KUNIT_ALL_TESTS
2665	help
2666	  This builds the bits unit test.
2667	  Tests the logic of macros defined in bits.h.
2668	  For more information on KUnit and unit tests in general please refer
2669	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2670
2671	  If unsure, say N.
2672
2673config SLUB_KUNIT_TEST
2674	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2675	depends on SLUB_DEBUG && KUNIT
2676	default KUNIT_ALL_TESTS
2677	help
2678	  This builds SLUB allocator unit test.
2679	  Tests SLUB cache debugging functionality.
2680	  For more information on KUnit and unit tests in general please refer
2681	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2682
2683	  If unsure, say N.
2684
2685config RATIONAL_KUNIT_TEST
2686	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2687	depends on KUNIT && RATIONAL
2688	default KUNIT_ALL_TESTS
2689	help
2690	  This builds the rational math unit test.
2691	  For more information on KUnit and unit tests in general please refer
2692	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2693
2694	  If unsure, say N.
2695
2696config MEMCPY_KUNIT_TEST
2697	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2698	depends on KUNIT
2699	default KUNIT_ALL_TESTS
2700	help
2701	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2702	  For more information on KUnit and unit tests in general please refer
2703	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2704
2705	  If unsure, say N.
2706
2707config IS_SIGNED_TYPE_KUNIT_TEST
2708	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2709	depends on KUNIT
2710	default KUNIT_ALL_TESTS
2711	help
2712	  Builds unit tests for the is_signed_type() macro.
2713
2714	  For more information on KUnit and unit tests in general please refer
2715	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2716
2717	  If unsure, say N.
2718
2719config OVERFLOW_KUNIT_TEST
2720	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2721	depends on KUNIT
2722	default KUNIT_ALL_TESTS
2723	help
2724	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2725	  related functions.
2726
2727	  For more information on KUnit and unit tests in general please refer
2728	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2729
2730	  If unsure, say N.
2731
2732config STACKINIT_KUNIT_TEST
2733	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2734	depends on KUNIT
2735	default KUNIT_ALL_TESTS
2736	help
2737	  Test if the kernel is zero-initializing stack variables and
2738	  padding. Coverage is controlled by compiler flags,
2739	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2740	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2741	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2742
2743config FORTIFY_KUNIT_TEST
2744	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2745	depends on KUNIT
2746	default KUNIT_ALL_TESTS
2747	help
2748	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2749	  by the str*() and mem*() family of functions. For testing runtime
2750	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2751
2752config HW_BREAKPOINT_KUNIT_TEST
2753	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2754	depends on HAVE_HW_BREAKPOINT
2755	depends on KUNIT=y
2756	default KUNIT_ALL_TESTS
2757	help
2758	  Tests for hw_breakpoint constraints accounting.
2759
2760	  If unsure, say N.
2761
2762config STRCAT_KUNIT_TEST
2763	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2764	depends on KUNIT
2765	default KUNIT_ALL_TESTS
2766
2767config STRSCPY_KUNIT_TEST
2768	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2769	depends on KUNIT
2770	default KUNIT_ALL_TESTS
2771
2772config SIPHASH_KUNIT_TEST
2773	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2774	depends on KUNIT
2775	default KUNIT_ALL_TESTS
2776	help
2777	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2778	  functions on boot (or module load).
2779
2780	  This is intended to help people writing architecture-specific
2781	  optimized versions.  If unsure, say N.
2782
2783config TEST_UDELAY
2784	tristate "udelay test driver"
2785	help
2786	  This builds the "udelay_test" module that helps to make sure
2787	  that udelay() is working properly.
2788
2789	  If unsure, say N.
2790
2791config TEST_STATIC_KEYS
2792	tristate "Test static keys"
2793	depends on m
2794	help
2795	  Test the static key interfaces.
2796
2797	  If unsure, say N.
2798
2799config TEST_DYNAMIC_DEBUG
2800	tristate "Test DYNAMIC_DEBUG"
2801	depends on DYNAMIC_DEBUG
2802	help
2803	  This module registers a tracer callback to count enabled
2804	  pr_debugs in a 'do_debugging' function, then alters their
2805	  enablements, calls the function, and compares counts.
2806
2807	  If unsure, say N.
2808
2809config TEST_KMOD
2810	tristate "kmod stress tester"
2811	depends on m
2812	depends on NETDEVICES && NET_CORE && INET # for TUN
2813	depends on BLOCK
2814	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2815	select TEST_LKM
2816	select XFS_FS
2817	select TUN
2818	select BTRFS_FS
2819	help
2820	  Test the kernel's module loading mechanism: kmod. kmod implements
2821	  support to load modules using the Linux kernel's usermode helper.
2822	  This test provides a series of tests against kmod.
2823
2824	  Although technically you can either build test_kmod as a module or
2825	  into the kernel we disallow building it into the kernel since
2826	  it stress tests request_module() and this will very likely cause
2827	  some issues by taking over precious threads available from other
2828	  module load requests, ultimately this could be fatal.
2829
2830	  To run tests run:
2831
2832	  tools/testing/selftests/kmod/kmod.sh --help
2833
2834	  If unsure, say N.
2835
2836config TEST_DEBUG_VIRTUAL
2837	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2838	depends on DEBUG_VIRTUAL
2839	help
2840	  Test the kernel's ability to detect incorrect calls to
2841	  virt_to_phys() done against the non-linear part of the
2842	  kernel's virtual address map.
2843
2844	  If unsure, say N.
2845
2846config TEST_MEMCAT_P
2847	tristate "Test memcat_p() helper function"
2848	help
2849	  Test the memcat_p() helper for correctly merging two
2850	  pointer arrays together.
2851
2852	  If unsure, say N.
2853
2854config TEST_OBJAGG
2855	tristate "Perform selftest on object aggreration manager"
2856	default n
2857	depends on OBJAGG
2858	help
2859	  Enable this option to test object aggregation manager on boot
2860	  (or module load).
2861
2862config TEST_MEMINIT
2863	tristate "Test heap/page initialization"
2864	help
2865	  Test if the kernel is zero-initializing heap and page allocations.
2866	  This can be useful to test init_on_alloc and init_on_free features.
2867
2868	  If unsure, say N.
2869
2870config TEST_HMM
2871	tristate "Test HMM (Heterogeneous Memory Management)"
2872	depends on TRANSPARENT_HUGEPAGE
2873	depends on DEVICE_PRIVATE
2874	select HMM_MIRROR
2875	select MMU_NOTIFIER
2876	help
2877	  This is a pseudo device driver solely for testing HMM.
2878	  Say M here if you want to build the HMM test module.
2879	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2880
2881	  If unsure, say N.
2882
2883config TEST_FREE_PAGES
2884	tristate "Test freeing pages"
2885	help
2886	  Test that a memory leak does not occur due to a race between
2887	  freeing a block of pages and a speculative page reference.
2888	  Loading this module is safe if your kernel has the bug fixed.
2889	  If the bug is not fixed, it will leak gigabytes of memory and
2890	  probably OOM your system.
2891
2892config TEST_FPU
2893	tristate "Test floating point operations in kernel space"
2894	depends on X86 && !KCOV_INSTRUMENT_ALL
2895	help
2896	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2897	  which will trigger a sequence of floating point operations. This is used
2898	  for self-testing floating point control register setting in
2899	  kernel_fpu_begin().
2900
2901	  If unsure, say N.
2902
2903config TEST_CLOCKSOURCE_WATCHDOG
2904	tristate "Test clocksource watchdog in kernel space"
2905	depends on CLOCKSOURCE_WATCHDOG
2906	help
2907	  Enable this option to create a kernel module that will trigger
2908	  a test of the clocksource watchdog.  This module may be loaded
2909	  via modprobe or insmod in which case it will run upon being
2910	  loaded, or it may be built in, in which case it will run
2911	  shortly after boot.
2912
2913	  If unsure, say N.
2914
2915config TEST_OBJPOOL
2916	tristate "Test module for correctness and stress of objpool"
2917	default n
2918	depends on m && DEBUG_KERNEL
2919	help
2920	  This builds the "test_objpool" module that should be used for
2921	  correctness verification and concurrent testings of objects
2922	  allocation and reclamation.
2923
2924	  If unsure, say N.
2925
2926endif # RUNTIME_TESTING_MENU
2927
2928config ARCH_USE_MEMTEST
2929	bool
2930	help
2931	  An architecture should select this when it uses early_memtest()
2932	  during boot process.
2933
2934config MEMTEST
2935	bool "Memtest"
2936	depends on ARCH_USE_MEMTEST
2937	help
2938	  This option adds a kernel parameter 'memtest', which allows memtest
2939	  to be set and executed.
2940	        memtest=0, mean disabled; -- default
2941	        memtest=1, mean do 1 test pattern;
2942	        ...
2943	        memtest=17, mean do 17 test patterns.
2944	  If you are unsure how to answer this question, answer N.
2945
2946
2947
2948config HYPERV_TESTING
2949	bool "Microsoft Hyper-V driver testing"
2950	default n
2951	depends on HYPERV && DEBUG_FS
2952	help
2953	  Select this option to enable Hyper-V vmbus testing.
2954
2955endmenu # "Kernel Testing and Coverage"
2956
2957menu "Rust hacking"
2958
2959config RUST_DEBUG_ASSERTIONS
2960	bool "Debug assertions"
2961	depends on RUST
2962	help
2963	  Enables rustc's `-Cdebug-assertions` codegen option.
2964
2965	  This flag lets you turn `cfg(debug_assertions)` conditional
2966	  compilation on or off. This can be used to enable extra debugging
2967	  code in development but not in production. For example, it controls
2968	  the behavior of the standard library's `debug_assert!` macro.
2969
2970	  Note that this will apply to all Rust code, including `core`.
2971
2972	  If unsure, say N.
2973
2974config RUST_OVERFLOW_CHECKS
2975	bool "Overflow checks"
2976	default y
2977	depends on RUST
2978	help
2979	  Enables rustc's `-Coverflow-checks` codegen option.
2980
2981	  This flag allows you to control the behavior of runtime integer
2982	  overflow. When overflow-checks are enabled, a Rust panic will occur
2983	  on overflow.
2984
2985	  Note that this will apply to all Rust code, including `core`.
2986
2987	  If unsure, say Y.
2988
2989config RUST_BUILD_ASSERT_ALLOW
2990	bool "Allow unoptimized build-time assertions"
2991	depends on RUST
2992	help
2993	  Controls how are `build_error!` and `build_assert!` handled during build.
2994
2995	  If calls to them exist in the binary, it may indicate a violated invariant
2996	  or that the optimizer failed to verify the invariant during compilation.
2997
2998	  This should not happen, thus by default the build is aborted. However,
2999	  as an escape hatch, you can choose Y here to ignore them during build
3000	  and let the check be carried at runtime (with `panic!` being called if
3001	  the check fails).
3002
3003	  If unsure, say N.
3004
3005config RUST_KERNEL_DOCTESTS
3006	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3007	depends on RUST && KUNIT=y
3008	default KUNIT_ALL_TESTS
3009	help
3010	  This builds the documentation tests of the `kernel` crate
3011	  as KUnit tests.
3012
3013	  For more information on KUnit and unit tests in general,
3014	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3015
3016	  If unsure, say N.
3017
3018endmenu # "Rust"
3019
3020endmenu # Kernel hacking
3021