xref: /linux/lib/Kconfig.debug (revision f73a058be5d70dd81a43f16b2bbff4b1576a7af8)
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
972config CODE_TAGGING
973	bool
974	select KALLSYMS
975
976config MEM_ALLOC_PROFILING
977	bool "Enable memory allocation profiling"
978	default n
979	depends on PROC_FS
980	depends on !DEBUG_FORCE_WEAK_PER_CPU
981	select CODE_TAGGING
982	select PAGE_EXTENSION
983	select SLAB_OBJ_EXT
984	help
985	  Track allocation source code and record total allocation size
986	  initiated at that code location. The mechanism can be used to track
987	  memory leaks with a low performance and memory impact.
988
989config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
990	bool "Enable memory allocation profiling by default"
991	default y
992	depends on MEM_ALLOC_PROFILING
993
994config MEM_ALLOC_PROFILING_DEBUG
995	bool "Memory allocation profiler debugging"
996	default n
997	depends on MEM_ALLOC_PROFILING
998	select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
999	help
1000	  Adds warnings with helpful error messages for memory allocation
1001	  profiling.
1002
1003source "lib/Kconfig.kasan"
1004source "lib/Kconfig.kfence"
1005source "lib/Kconfig.kmsan"
1006
1007endmenu # "Memory Debugging"
1008
1009config DEBUG_SHIRQ
1010	bool "Debug shared IRQ handlers"
1011	depends on DEBUG_KERNEL
1012	help
1013	  Enable this to generate a spurious interrupt just before a shared
1014	  interrupt handler is deregistered (generating one when registering
1015	  is currently disabled). Drivers need to handle this correctly. Some
1016	  don't and need to be caught.
1017
1018menu "Debug Oops, Lockups and Hangs"
1019
1020config PANIC_ON_OOPS
1021	bool "Panic on Oops"
1022	help
1023	  Say Y here to enable the kernel to panic when it oopses. This
1024	  has the same effect as setting oops=panic on the kernel command
1025	  line.
1026
1027	  This feature is useful to ensure that the kernel does not do
1028	  anything erroneous after an oops which could result in data
1029	  corruption or other issues.
1030
1031	  Say N if unsure.
1032
1033config PANIC_ON_OOPS_VALUE
1034	int
1035	range 0 1
1036	default 0 if !PANIC_ON_OOPS
1037	default 1 if PANIC_ON_OOPS
1038
1039config PANIC_TIMEOUT
1040	int "panic timeout"
1041	default 0
1042	help
1043	  Set the timeout value (in seconds) until a reboot occurs when
1044	  the kernel panics. If n = 0, then we wait forever. A timeout
1045	  value n > 0 will wait n seconds before rebooting, while a timeout
1046	  value n < 0 will reboot immediately.
1047
1048config LOCKUP_DETECTOR
1049	bool
1050
1051config SOFTLOCKUP_DETECTOR
1052	bool "Detect Soft Lockups"
1053	depends on DEBUG_KERNEL && !S390
1054	select LOCKUP_DETECTOR
1055	help
1056	  Say Y here to enable the kernel to act as a watchdog to detect
1057	  soft lockups.
1058
1059	  Softlockups are bugs that cause the kernel to loop in kernel
1060	  mode for more than 20 seconds, without giving other tasks a
1061	  chance to run.  The current stack trace is displayed upon
1062	  detection and the system will stay locked up.
1063
1064config SOFTLOCKUP_DETECTOR_INTR_STORM
1065	bool "Detect Interrupt Storm in Soft Lockups"
1066	depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
1067	select GENERIC_IRQ_STAT_SNAPSHOT
1068	default y if NR_CPUS <= 128
1069	help
1070	  Say Y here to enable the kernel to detect interrupt storm
1071	  during "soft lockups".
1072
1073	  "soft lockups" can be caused by a variety of reasons. If one is
1074	  caused by an interrupt storm, then the storming interrupts will not
1075	  be on the callstack. To detect this case, it is necessary to report
1076	  the CPU stats and the interrupt counts during the "soft lockups".
1077
1078config BOOTPARAM_SOFTLOCKUP_PANIC
1079	bool "Panic (Reboot) On Soft Lockups"
1080	depends on SOFTLOCKUP_DETECTOR
1081	help
1082	  Say Y here to enable the kernel to panic on "soft lockups",
1083	  which are bugs that cause the kernel to loop in kernel
1084	  mode for more than 20 seconds (configurable using the watchdog_thresh
1085	  sysctl), without giving other tasks a chance to run.
1086
1087	  The panic can be used in combination with panic_timeout,
1088	  to cause the system to reboot automatically after a
1089	  lockup has been detected. This feature is useful for
1090	  high-availability systems that have uptime guarantees and
1091	  where a lockup must be resolved ASAP.
1092
1093	  Say N if unsure.
1094
1095config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1096	bool
1097	depends on SMP
1098	default y
1099
1100#
1101# Global switch whether to build a hardlockup detector at all. It is available
1102# only when the architecture supports at least one implementation. There are
1103# two exceptions. The hardlockup detector is never enabled on:
1104#
1105#	s390: it reported many false positives there
1106#
1107#	sparc64: has a custom implementation which is not using the common
1108#		hardlockup command line options and sysctl interface.
1109#
1110config HARDLOCKUP_DETECTOR
1111	bool "Detect Hard Lockups"
1112	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1113	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1114	imply HARDLOCKUP_DETECTOR_PERF
1115	imply HARDLOCKUP_DETECTOR_BUDDY
1116	imply HARDLOCKUP_DETECTOR_ARCH
1117	select LOCKUP_DETECTOR
1118
1119	help
1120	  Say Y here to enable the kernel to act as a watchdog to detect
1121	  hard lockups.
1122
1123	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1124	  for more than 10 seconds, without letting other interrupts have a
1125	  chance to run.  The current stack trace is displayed upon detection
1126	  and the system will stay locked up.
1127
1128#
1129# Note that arch-specific variants are always preferred.
1130#
1131config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1132	bool "Prefer the buddy CPU hardlockup detector"
1133	depends on HARDLOCKUP_DETECTOR
1134	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1135	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1136	help
1137	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1138
1139	  With the buddy detector, each CPU uses its softlockup hrtimer
1140	  to check that the next CPU is processing hrtimer interrupts by
1141	  verifying that a counter is increasing.
1142
1143	  This hardlockup detector is useful on systems that don't have
1144	  an arch-specific hardlockup detector or if resources needed
1145	  for the hardlockup detector are better used for other things.
1146
1147config HARDLOCKUP_DETECTOR_PERF
1148	bool
1149	depends on HARDLOCKUP_DETECTOR
1150	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1151	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1152	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1153
1154config HARDLOCKUP_DETECTOR_BUDDY
1155	bool
1156	depends on HARDLOCKUP_DETECTOR
1157	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1158	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1159	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1160	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1161
1162config HARDLOCKUP_DETECTOR_ARCH
1163	bool
1164	depends on HARDLOCKUP_DETECTOR
1165	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1166	help
1167	  The arch-specific implementation of the hardlockup detector will
1168	  be used.
1169
1170#
1171# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1172# interrupts. This config enables functions managing this common code.
1173#
1174config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1175	bool
1176	select SOFTLOCKUP_DETECTOR
1177
1178#
1179# Enables a timestamp based low pass filter to compensate for perf based
1180# hard lockup detection which runs too fast due to turbo modes.
1181#
1182config HARDLOCKUP_CHECK_TIMESTAMP
1183	bool
1184
1185config BOOTPARAM_HARDLOCKUP_PANIC
1186	bool "Panic (Reboot) On Hard Lockups"
1187	depends on HARDLOCKUP_DETECTOR
1188	help
1189	  Say Y here to enable the kernel to panic on "hard lockups",
1190	  which are bugs that cause the kernel to loop in kernel
1191	  mode with interrupts disabled for more than 10 seconds (configurable
1192	  using the watchdog_thresh sysctl).
1193
1194	  Say N if unsure.
1195
1196config DETECT_HUNG_TASK
1197	bool "Detect Hung Tasks"
1198	depends on DEBUG_KERNEL
1199	default SOFTLOCKUP_DETECTOR
1200	help
1201	  Say Y here to enable the kernel to detect "hung tasks",
1202	  which are bugs that cause the task to be stuck in
1203	  uninterruptible "D" state indefinitely.
1204
1205	  When a hung task is detected, the kernel will print the
1206	  current stack trace (which you should report), but the
1207	  task will stay in uninterruptible state. If lockdep is
1208	  enabled then all held locks will also be reported. This
1209	  feature has negligible overhead.
1210
1211config DEFAULT_HUNG_TASK_TIMEOUT
1212	int "Default timeout for hung task detection (in seconds)"
1213	depends on DETECT_HUNG_TASK
1214	default 120
1215	help
1216	  This option controls the default timeout (in seconds) used
1217	  to determine when a task has become non-responsive and should
1218	  be considered hung.
1219
1220	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1221	  sysctl or by writing a value to
1222	  /proc/sys/kernel/hung_task_timeout_secs.
1223
1224	  A timeout of 0 disables the check.  The default is two minutes.
1225	  Keeping the default should be fine in most cases.
1226
1227config BOOTPARAM_HUNG_TASK_PANIC
1228	bool "Panic (Reboot) On Hung Tasks"
1229	depends on DETECT_HUNG_TASK
1230	help
1231	  Say Y here to enable the kernel to panic on "hung tasks",
1232	  which are bugs that cause the kernel to leave a task stuck
1233	  in uninterruptible "D" state.
1234
1235	  The panic can be used in combination with panic_timeout,
1236	  to cause the system to reboot automatically after a
1237	  hung task has been detected. This feature is useful for
1238	  high-availability systems that have uptime guarantees and
1239	  where a hung tasks must be resolved ASAP.
1240
1241	  Say N if unsure.
1242
1243config WQ_WATCHDOG
1244	bool "Detect Workqueue Stalls"
1245	depends on DEBUG_KERNEL
1246	help
1247	  Say Y here to enable stall detection on workqueues.  If a
1248	  worker pool doesn't make forward progress on a pending work
1249	  item for over a given amount of time, 30s by default, a
1250	  warning message is printed along with dump of workqueue
1251	  state.  This can be configured through kernel parameter
1252	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1253
1254config WQ_CPU_INTENSIVE_REPORT
1255	bool "Report per-cpu work items which hog CPU for too long"
1256	depends on DEBUG_KERNEL
1257	help
1258	  Say Y here to enable reporting of concurrency-managed per-cpu work
1259	  items that hog CPUs for longer than
1260	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1261	  detects and excludes them from concurrency management to prevent
1262	  them from stalling other per-cpu work items. Occassional
1263	  triggering may not necessarily indicate a problem. Repeated
1264	  triggering likely indicates that the work item should be switched
1265	  to use an unbound workqueue.
1266
1267config TEST_LOCKUP
1268	tristate "Test module to generate lockups"
1269	depends on m
1270	help
1271	  This builds the "test_lockup" module that helps to make sure
1272	  that watchdogs and lockup detectors are working properly.
1273
1274	  Depending on module parameters it could emulate soft or hard
1275	  lockup, "hung task", or locking arbitrary lock for a long time.
1276	  Also it could generate series of lockups with cooling-down periods.
1277
1278	  If unsure, say N.
1279
1280endmenu # "Debug lockups and hangs"
1281
1282menu "Scheduler Debugging"
1283
1284config SCHED_DEBUG
1285	bool "Collect scheduler debugging info"
1286	depends on DEBUG_KERNEL && DEBUG_FS
1287	default y
1288	help
1289	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1290	  that can help debug the scheduler. The runtime overhead of this
1291	  option is minimal.
1292
1293config SCHED_INFO
1294	bool
1295	default n
1296
1297config SCHEDSTATS
1298	bool "Collect scheduler statistics"
1299	depends on PROC_FS
1300	select SCHED_INFO
1301	help
1302	  If you say Y here, additional code will be inserted into the
1303	  scheduler and related routines to collect statistics about
1304	  scheduler behavior and provide them in /proc/schedstat.  These
1305	  stats may be useful for both tuning and debugging the scheduler
1306	  If you aren't debugging the scheduler or trying to tune a specific
1307	  application, you can say N to avoid the very slight overhead
1308	  this adds.
1309
1310endmenu
1311
1312config DEBUG_TIMEKEEPING
1313	bool "Enable extra timekeeping sanity checking"
1314	help
1315	  This option will enable additional timekeeping sanity checks
1316	  which may be helpful when diagnosing issues where timekeeping
1317	  problems are suspected.
1318
1319	  This may include checks in the timekeeping hotpaths, so this
1320	  option may have a (very small) performance impact to some
1321	  workloads.
1322
1323	  If unsure, say N.
1324
1325config DEBUG_PREEMPT
1326	bool "Debug preemptible kernel"
1327	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1328	help
1329	  If you say Y here then the kernel will use a debug variant of the
1330	  commonly used smp_processor_id() function and will print warnings
1331	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1332	  will detect preemption count underflows.
1333
1334	  This option has potential to introduce high runtime overhead,
1335	  depending on workload as it triggers debugging routines for each
1336	  this_cpu operation. It should only be used for debugging purposes.
1337
1338menu "Lock Debugging (spinlocks, mutexes, etc...)"
1339
1340config LOCK_DEBUGGING_SUPPORT
1341	bool
1342	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1343	default y
1344
1345config PROVE_LOCKING
1346	bool "Lock debugging: prove locking correctness"
1347	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1348	select LOCKDEP
1349	select DEBUG_SPINLOCK
1350	select DEBUG_MUTEXES if !PREEMPT_RT
1351	select DEBUG_RT_MUTEXES if RT_MUTEXES
1352	select DEBUG_RWSEMS if !PREEMPT_RT
1353	select DEBUG_WW_MUTEX_SLOWPATH
1354	select DEBUG_LOCK_ALLOC
1355	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1356	select TRACE_IRQFLAGS
1357	default n
1358	help
1359	 This feature enables the kernel to prove that all locking
1360	 that occurs in the kernel runtime is mathematically
1361	 correct: that under no circumstance could an arbitrary (and
1362	 not yet triggered) combination of observed locking
1363	 sequences (on an arbitrary number of CPUs, running an
1364	 arbitrary number of tasks and interrupt contexts) cause a
1365	 deadlock.
1366
1367	 In short, this feature enables the kernel to report locking
1368	 related deadlocks before they actually occur.
1369
1370	 The proof does not depend on how hard and complex a
1371	 deadlock scenario would be to trigger: how many
1372	 participant CPUs, tasks and irq-contexts would be needed
1373	 for it to trigger. The proof also does not depend on
1374	 timing: if a race and a resulting deadlock is possible
1375	 theoretically (no matter how unlikely the race scenario
1376	 is), it will be proven so and will immediately be
1377	 reported by the kernel (once the event is observed that
1378	 makes the deadlock theoretically possible).
1379
1380	 If a deadlock is impossible (i.e. the locking rules, as
1381	 observed by the kernel, are mathematically correct), the
1382	 kernel reports nothing.
1383
1384	 NOTE: this feature can also be enabled for rwlocks, mutexes
1385	 and rwsems - in which case all dependencies between these
1386	 different locking variants are observed and mapped too, and
1387	 the proof of observed correctness is also maintained for an
1388	 arbitrary combination of these separate locking variants.
1389
1390	 For more details, see Documentation/locking/lockdep-design.rst.
1391
1392config PROVE_RAW_LOCK_NESTING
1393	bool "Enable raw_spinlock - spinlock nesting checks"
1394	depends on PROVE_LOCKING
1395	default n
1396	help
1397	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1398	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1399	 not violated.
1400
1401	 NOTE: There are known nesting problems. So if you enable this
1402	 option expect lockdep splats until these problems have been fully
1403	 addressed which is work in progress. This config switch allows to
1404	 identify and analyze these problems. It will be removed and the
1405	 check permanently enabled once the main issues have been fixed.
1406
1407	 If unsure, select N.
1408
1409config LOCK_STAT
1410	bool "Lock usage statistics"
1411	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1412	select LOCKDEP
1413	select DEBUG_SPINLOCK
1414	select DEBUG_MUTEXES if !PREEMPT_RT
1415	select DEBUG_RT_MUTEXES if RT_MUTEXES
1416	select DEBUG_LOCK_ALLOC
1417	default n
1418	help
1419	 This feature enables tracking lock contention points
1420
1421	 For more details, see Documentation/locking/lockstat.rst
1422
1423	 This also enables lock events required by "perf lock",
1424	 subcommand of perf.
1425	 If you want to use "perf lock", you also need to turn on
1426	 CONFIG_EVENT_TRACING.
1427
1428	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1429	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1430
1431config DEBUG_RT_MUTEXES
1432	bool "RT Mutex debugging, deadlock detection"
1433	depends on DEBUG_KERNEL && RT_MUTEXES
1434	help
1435	 This allows rt mutex semantics violations and rt mutex related
1436	 deadlocks (lockups) to be detected and reported automatically.
1437
1438config DEBUG_SPINLOCK
1439	bool "Spinlock and rw-lock debugging: basic checks"
1440	depends on DEBUG_KERNEL
1441	select UNINLINE_SPIN_UNLOCK
1442	help
1443	  Say Y here and build SMP to catch missing spinlock initialization
1444	  and certain other kinds of spinlock errors commonly made.  This is
1445	  best used in conjunction with the NMI watchdog so that spinlock
1446	  deadlocks are also debuggable.
1447
1448config DEBUG_MUTEXES
1449	bool "Mutex debugging: basic checks"
1450	depends on DEBUG_KERNEL && !PREEMPT_RT
1451	help
1452	 This feature allows mutex semantics violations to be detected and
1453	 reported.
1454
1455config DEBUG_WW_MUTEX_SLOWPATH
1456	bool "Wait/wound mutex debugging: Slowpath testing"
1457	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1458	select DEBUG_LOCK_ALLOC
1459	select DEBUG_SPINLOCK
1460	select DEBUG_MUTEXES if !PREEMPT_RT
1461	select DEBUG_RT_MUTEXES if PREEMPT_RT
1462	help
1463	 This feature enables slowpath testing for w/w mutex users by
1464	 injecting additional -EDEADLK wound/backoff cases. Together with
1465	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1466	 will test all possible w/w mutex interface abuse with the
1467	 exception of simply not acquiring all the required locks.
1468	 Note that this feature can introduce significant overhead, so
1469	 it really should not be enabled in a production or distro kernel,
1470	 even a debug kernel.  If you are a driver writer, enable it.  If
1471	 you are a distro, do not.
1472
1473config DEBUG_RWSEMS
1474	bool "RW Semaphore debugging: basic checks"
1475	depends on DEBUG_KERNEL && !PREEMPT_RT
1476	help
1477	  This debugging feature allows mismatched rw semaphore locks
1478	  and unlocks to be detected and reported.
1479
1480config DEBUG_LOCK_ALLOC
1481	bool "Lock debugging: detect incorrect freeing of live locks"
1482	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1483	select DEBUG_SPINLOCK
1484	select DEBUG_MUTEXES if !PREEMPT_RT
1485	select DEBUG_RT_MUTEXES if RT_MUTEXES
1486	select LOCKDEP
1487	help
1488	 This feature will check whether any held lock (spinlock, rwlock,
1489	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1490	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1491	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1492	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1493	 held during task exit.
1494
1495config LOCKDEP
1496	bool
1497	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1498	select STACKTRACE
1499	select KALLSYMS
1500	select KALLSYMS_ALL
1501
1502config LOCKDEP_SMALL
1503	bool
1504
1505config LOCKDEP_BITS
1506	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1507	depends on LOCKDEP && !LOCKDEP_SMALL
1508	range 10 30
1509	default 15
1510	help
1511	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1512
1513config LOCKDEP_CHAINS_BITS
1514	int "Bitsize for MAX_LOCKDEP_CHAINS"
1515	depends on LOCKDEP && !LOCKDEP_SMALL
1516	range 10 30
1517	default 16
1518	help
1519	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1520
1521config LOCKDEP_STACK_TRACE_BITS
1522	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1523	depends on LOCKDEP && !LOCKDEP_SMALL
1524	range 10 30
1525	default 19
1526	help
1527	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1528
1529config LOCKDEP_STACK_TRACE_HASH_BITS
1530	int "Bitsize for STACK_TRACE_HASH_SIZE"
1531	depends on LOCKDEP && !LOCKDEP_SMALL
1532	range 10 30
1533	default 14
1534	help
1535	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1536
1537config LOCKDEP_CIRCULAR_QUEUE_BITS
1538	int "Bitsize for elements in circular_queue struct"
1539	depends on LOCKDEP
1540	range 10 30
1541	default 12
1542	help
1543	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1544
1545config DEBUG_LOCKDEP
1546	bool "Lock dependency engine debugging"
1547	depends on DEBUG_KERNEL && LOCKDEP
1548	select DEBUG_IRQFLAGS
1549	help
1550	  If you say Y here, the lock dependency engine will do
1551	  additional runtime checks to debug itself, at the price
1552	  of more runtime overhead.
1553
1554config DEBUG_ATOMIC_SLEEP
1555	bool "Sleep inside atomic section checking"
1556	select PREEMPT_COUNT
1557	depends on DEBUG_KERNEL
1558	depends on !ARCH_NO_PREEMPT
1559	help
1560	  If you say Y here, various routines which may sleep will become very
1561	  noisy if they are called inside atomic sections: when a spinlock is
1562	  held, inside an rcu read side critical section, inside preempt disabled
1563	  sections, inside an interrupt, etc...
1564
1565config DEBUG_LOCKING_API_SELFTESTS
1566	bool "Locking API boot-time self-tests"
1567	depends on DEBUG_KERNEL
1568	help
1569	  Say Y here if you want the kernel to run a short self-test during
1570	  bootup. The self-test checks whether common types of locking bugs
1571	  are detected by debugging mechanisms or not. (if you disable
1572	  lock debugging then those bugs won't be detected of course.)
1573	  The following locking APIs are covered: spinlocks, rwlocks,
1574	  mutexes and rwsems.
1575
1576config LOCK_TORTURE_TEST
1577	tristate "torture tests for locking"
1578	depends on DEBUG_KERNEL
1579	select TORTURE_TEST
1580	help
1581	  This option provides a kernel module that runs torture tests
1582	  on kernel locking primitives.  The kernel module may be built
1583	  after the fact on the running kernel to be tested, if desired.
1584
1585	  Say Y here if you want kernel locking-primitive torture tests
1586	  to be built into the kernel.
1587	  Say M if you want these torture tests to build as a module.
1588	  Say N if you are unsure.
1589
1590config WW_MUTEX_SELFTEST
1591	tristate "Wait/wound mutex selftests"
1592	help
1593	  This option provides a kernel module that runs tests on the
1594	  on the struct ww_mutex locking API.
1595
1596	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1597	  with this test harness.
1598
1599	  Say M if you want these self tests to build as a module.
1600	  Say N if you are unsure.
1601
1602config SCF_TORTURE_TEST
1603	tristate "torture tests for smp_call_function*()"
1604	depends on DEBUG_KERNEL
1605	select TORTURE_TEST
1606	help
1607	  This option provides a kernel module that runs torture tests
1608	  on the smp_call_function() family of primitives.  The kernel
1609	  module may be built after the fact on the running kernel to
1610	  be tested, if desired.
1611
1612config CSD_LOCK_WAIT_DEBUG
1613	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1614	depends on DEBUG_KERNEL
1615	depends on 64BIT
1616	default n
1617	help
1618	  This option enables debug prints when CPUs are slow to respond
1619	  to the smp_call_function*() IPI wrappers.  These debug prints
1620	  include the IPI handler function currently executing (if any)
1621	  and relevant stack traces.
1622
1623config CSD_LOCK_WAIT_DEBUG_DEFAULT
1624	bool "Default csd_lock_wait() debugging on at boot time"
1625	depends on CSD_LOCK_WAIT_DEBUG
1626	depends on 64BIT
1627	default n
1628	help
1629	  This option causes the csdlock_debug= kernel boot parameter to
1630	  default to 1 (basic debugging) instead of 0 (no debugging).
1631
1632endmenu # lock debugging
1633
1634config TRACE_IRQFLAGS
1635	depends on TRACE_IRQFLAGS_SUPPORT
1636	bool
1637	help
1638	  Enables hooks to interrupt enabling and disabling for
1639	  either tracing or lock debugging.
1640
1641config TRACE_IRQFLAGS_NMI
1642	def_bool y
1643	depends on TRACE_IRQFLAGS
1644	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1645
1646config NMI_CHECK_CPU
1647	bool "Debugging for CPUs failing to respond to backtrace requests"
1648	depends on DEBUG_KERNEL
1649	depends on X86
1650	default n
1651	help
1652	  Enables debug prints when a CPU fails to respond to a given
1653	  backtrace NMI.  These prints provide some reasons why a CPU
1654	  might legitimately be failing to respond, for example, if it
1655	  is offline of if ignore_nmis is set.
1656
1657config DEBUG_IRQFLAGS
1658	bool "Debug IRQ flag manipulation"
1659	help
1660	  Enables checks for potentially unsafe enabling or disabling of
1661	  interrupts, such as calling raw_local_irq_restore() when interrupts
1662	  are enabled.
1663
1664config STACKTRACE
1665	bool "Stack backtrace support"
1666	depends on STACKTRACE_SUPPORT
1667	help
1668	  This option causes the kernel to create a /proc/pid/stack for
1669	  every process, showing its current stack trace.
1670	  It is also used by various kernel debugging features that require
1671	  stack trace generation.
1672
1673config WARN_ALL_UNSEEDED_RANDOM
1674	bool "Warn for all uses of unseeded randomness"
1675	default n
1676	help
1677	  Some parts of the kernel contain bugs relating to their use of
1678	  cryptographically secure random numbers before it's actually possible
1679	  to generate those numbers securely. This setting ensures that these
1680	  flaws don't go unnoticed, by enabling a message, should this ever
1681	  occur. This will allow people with obscure setups to know when things
1682	  are going wrong, so that they might contact developers about fixing
1683	  it.
1684
1685	  Unfortunately, on some models of some architectures getting
1686	  a fully seeded CRNG is extremely difficult, and so this can
1687	  result in dmesg getting spammed for a surprisingly long
1688	  time.  This is really bad from a security perspective, and
1689	  so architecture maintainers really need to do what they can
1690	  to get the CRNG seeded sooner after the system is booted.
1691	  However, since users cannot do anything actionable to
1692	  address this, by default this option is disabled.
1693
1694	  Say Y here if you want to receive warnings for all uses of
1695	  unseeded randomness.  This will be of use primarily for
1696	  those developers interested in improving the security of
1697	  Linux kernels running on their architecture (or
1698	  subarchitecture).
1699
1700config DEBUG_KOBJECT
1701	bool "kobject debugging"
1702	depends on DEBUG_KERNEL
1703	help
1704	  If you say Y here, some extra kobject debugging messages will be sent
1705	  to the syslog.
1706
1707config DEBUG_KOBJECT_RELEASE
1708	bool "kobject release debugging"
1709	depends on DEBUG_OBJECTS_TIMERS
1710	help
1711	  kobjects are reference counted objects.  This means that their
1712	  last reference count put is not predictable, and the kobject can
1713	  live on past the point at which a driver decides to drop its
1714	  initial reference to the kobject gained on allocation.  An
1715	  example of this would be a struct device which has just been
1716	  unregistered.
1717
1718	  However, some buggy drivers assume that after such an operation,
1719	  the memory backing the kobject can be immediately freed.  This
1720	  goes completely against the principles of a refcounted object.
1721
1722	  If you say Y here, the kernel will delay the release of kobjects
1723	  on the last reference count to improve the visibility of this
1724	  kind of kobject release bug.
1725
1726config HAVE_DEBUG_BUGVERBOSE
1727	bool
1728
1729menu "Debug kernel data structures"
1730
1731config DEBUG_LIST
1732	bool "Debug linked list manipulation"
1733	depends on DEBUG_KERNEL
1734	select LIST_HARDENED
1735	help
1736	  Enable this to turn on extended checks in the linked-list walking
1737	  routines.
1738
1739	  This option trades better quality error reports for performance, and
1740	  is more suitable for kernel debugging. If you care about performance,
1741	  you should only enable CONFIG_LIST_HARDENED instead.
1742
1743	  If unsure, say N.
1744
1745config DEBUG_PLIST
1746	bool "Debug priority linked list manipulation"
1747	depends on DEBUG_KERNEL
1748	help
1749	  Enable this to turn on extended checks in the priority-ordered
1750	  linked-list (plist) walking routines.  This checks the entire
1751	  list multiple times during each manipulation.
1752
1753	  If unsure, say N.
1754
1755config DEBUG_SG
1756	bool "Debug SG table operations"
1757	depends on DEBUG_KERNEL
1758	help
1759	  Enable this to turn on checks on scatter-gather tables. This can
1760	  help find problems with drivers that do not properly initialize
1761	  their sg tables.
1762
1763	  If unsure, say N.
1764
1765config DEBUG_NOTIFIERS
1766	bool "Debug notifier call chains"
1767	depends on DEBUG_KERNEL
1768	help
1769	  Enable this to turn on sanity checking for notifier call chains.
1770	  This is most useful for kernel developers to make sure that
1771	  modules properly unregister themselves from notifier chains.
1772	  This is a relatively cheap check but if you care about maximum
1773	  performance, say N.
1774
1775config DEBUG_CLOSURES
1776	bool "Debug closures (bcache async widgits)"
1777	depends on CLOSURES
1778	select DEBUG_FS
1779	help
1780	  Keeps all active closures in a linked list and provides a debugfs
1781	  interface to list them, which makes it possible to see asynchronous
1782	  operations that get stuck.
1783
1784config DEBUG_MAPLE_TREE
1785	bool "Debug maple trees"
1786	depends on DEBUG_KERNEL
1787	help
1788	  Enable maple tree debugging information and extra validations.
1789
1790	  If unsure, say N.
1791
1792endmenu
1793
1794source "kernel/rcu/Kconfig.debug"
1795
1796config DEBUG_WQ_FORCE_RR_CPU
1797	bool "Force round-robin CPU selection for unbound work items"
1798	depends on DEBUG_KERNEL
1799	default n
1800	help
1801	  Workqueue used to implicitly guarantee that work items queued
1802	  without explicit CPU specified are put on the local CPU.  This
1803	  guarantee is no longer true and while local CPU is still
1804	  preferred work items may be put on foreign CPUs.  Kernel
1805	  parameter "workqueue.debug_force_rr_cpu" is added to force
1806	  round-robin CPU selection to flush out usages which depend on the
1807	  now broken guarantee.  This config option enables the debug
1808	  feature by default.  When enabled, memory and cache locality will
1809	  be impacted.
1810
1811config CPU_HOTPLUG_STATE_CONTROL
1812	bool "Enable CPU hotplug state control"
1813	depends on DEBUG_KERNEL
1814	depends on HOTPLUG_CPU
1815	default n
1816	help
1817	  Allows to write steps between "offline" and "online" to the CPUs
1818	  sysfs target file so states can be stepped granular. This is a debug
1819	  option for now as the hotplug machinery cannot be stopped and
1820	  restarted at arbitrary points yet.
1821
1822	  Say N if your are unsure.
1823
1824config LATENCYTOP
1825	bool "Latency measuring infrastructure"
1826	depends on DEBUG_KERNEL
1827	depends on STACKTRACE_SUPPORT
1828	depends on PROC_FS
1829	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1830	select KALLSYMS
1831	select KALLSYMS_ALL
1832	select STACKTRACE
1833	select SCHEDSTATS
1834	help
1835	  Enable this option if you want to use the LatencyTOP tool
1836	  to find out which userspace is blocking on what kernel operations.
1837
1838config DEBUG_CGROUP_REF
1839	bool "Disable inlining of cgroup css reference count functions"
1840	depends on DEBUG_KERNEL
1841	depends on CGROUPS
1842	depends on KPROBES
1843	default n
1844	help
1845	  Force cgroup css reference count functions to not be inlined so
1846	  that they can be kprobed for debugging.
1847
1848source "kernel/trace/Kconfig"
1849
1850config PROVIDE_OHCI1394_DMA_INIT
1851	bool "Remote debugging over FireWire early on boot"
1852	depends on PCI && X86
1853	help
1854	  If you want to debug problems which hang or crash the kernel early
1855	  on boot and the crashing machine has a FireWire port, you can use
1856	  this feature to remotely access the memory of the crashed machine
1857	  over FireWire. This employs remote DMA as part of the OHCI1394
1858	  specification which is now the standard for FireWire controllers.
1859
1860	  With remote DMA, you can monitor the printk buffer remotely using
1861	  firescope and access all memory below 4GB using fireproxy from gdb.
1862	  Even controlling a kernel debugger is possible using remote DMA.
1863
1864	  Usage:
1865
1866	  If ohci1394_dma=early is used as boot parameter, it will initialize
1867	  all OHCI1394 controllers which are found in the PCI config space.
1868
1869	  As all changes to the FireWire bus such as enabling and disabling
1870	  devices cause a bus reset and thereby disable remote DMA for all
1871	  devices, be sure to have the cable plugged and FireWire enabled on
1872	  the debugging host before booting the debug target for debugging.
1873
1874	  This code (~1k) is freed after boot. By then, the firewire stack
1875	  in charge of the OHCI-1394 controllers should be used instead.
1876
1877	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1878
1879source "samples/Kconfig"
1880
1881config ARCH_HAS_DEVMEM_IS_ALLOWED
1882	bool
1883
1884config STRICT_DEVMEM
1885	bool "Filter access to /dev/mem"
1886	depends on MMU && DEVMEM
1887	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1888	default y if PPC || X86 || ARM64
1889	help
1890	  If this option is disabled, you allow userspace (root) access to all
1891	  of memory, including kernel and userspace memory. Accidental
1892	  access to this is obviously disastrous, but specific access can
1893	  be used by people debugging the kernel. Note that with PAT support
1894	  enabled, even in this case there are restrictions on /dev/mem
1895	  use due to the cache aliasing requirements.
1896
1897	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1898	  file only allows userspace access to PCI space and the BIOS code and
1899	  data regions.  This is sufficient for dosemu and X and all common
1900	  users of /dev/mem.
1901
1902	  If in doubt, say Y.
1903
1904config IO_STRICT_DEVMEM
1905	bool "Filter I/O access to /dev/mem"
1906	depends on STRICT_DEVMEM
1907	help
1908	  If this option is disabled, you allow userspace (root) access to all
1909	  io-memory regardless of whether a driver is actively using that
1910	  range.  Accidental access to this is obviously disastrous, but
1911	  specific access can be used by people debugging kernel drivers.
1912
1913	  If this option is switched on, the /dev/mem file only allows
1914	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1915	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1916	  if the driver using a given range cannot be disabled.
1917
1918	  If in doubt, say Y.
1919
1920menu "$(SRCARCH) Debugging"
1921
1922source "arch/$(SRCARCH)/Kconfig.debug"
1923
1924endmenu
1925
1926menu "Kernel Testing and Coverage"
1927
1928source "lib/kunit/Kconfig"
1929
1930config NOTIFIER_ERROR_INJECTION
1931	tristate "Notifier error injection"
1932	depends on DEBUG_KERNEL
1933	select DEBUG_FS
1934	help
1935	  This option provides the ability to inject artificial errors to
1936	  specified notifier chain callbacks. It is useful to test the error
1937	  handling of notifier call chain failures.
1938
1939	  Say N if unsure.
1940
1941config PM_NOTIFIER_ERROR_INJECT
1942	tristate "PM notifier error injection module"
1943	depends on PM && NOTIFIER_ERROR_INJECTION
1944	default m if PM_DEBUG
1945	help
1946	  This option provides the ability to inject artificial errors to
1947	  PM notifier chain callbacks.  It is controlled through debugfs
1948	  interface /sys/kernel/debug/notifier-error-inject/pm
1949
1950	  If the notifier call chain should be failed with some events
1951	  notified, write the error code to "actions/<notifier event>/error".
1952
1953	  Example: Inject PM suspend error (-12 = -ENOMEM)
1954
1955	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1956	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1957	  # echo mem > /sys/power/state
1958	  bash: echo: write error: Cannot allocate memory
1959
1960	  To compile this code as a module, choose M here: the module will
1961	  be called pm-notifier-error-inject.
1962
1963	  If unsure, say N.
1964
1965config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1966	tristate "OF reconfig notifier error injection module"
1967	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1968	help
1969	  This option provides the ability to inject artificial errors to
1970	  OF reconfig notifier chain callbacks.  It is controlled
1971	  through debugfs interface under
1972	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1973
1974	  If the notifier call chain should be failed with some events
1975	  notified, write the error code to "actions/<notifier event>/error".
1976
1977	  To compile this code as a module, choose M here: the module will
1978	  be called of-reconfig-notifier-error-inject.
1979
1980	  If unsure, say N.
1981
1982config NETDEV_NOTIFIER_ERROR_INJECT
1983	tristate "Netdev notifier error injection module"
1984	depends on NET && NOTIFIER_ERROR_INJECTION
1985	help
1986	  This option provides the ability to inject artificial errors to
1987	  netdevice notifier chain callbacks.  It is controlled through debugfs
1988	  interface /sys/kernel/debug/notifier-error-inject/netdev
1989
1990	  If the notifier call chain should be failed with some events
1991	  notified, write the error code to "actions/<notifier event>/error".
1992
1993	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1994
1995	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1996	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1997	  # ip link set eth0 mtu 1024
1998	  RTNETLINK answers: Invalid argument
1999
2000	  To compile this code as a module, choose M here: the module will
2001	  be called netdev-notifier-error-inject.
2002
2003	  If unsure, say N.
2004
2005config FUNCTION_ERROR_INJECTION
2006	bool "Fault-injections of functions"
2007	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
2008	help
2009	  Add fault injections into various functions that are annotated with
2010	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
2011	  value of these functions. This is useful to test error paths of code.
2012
2013	  If unsure, say N
2014
2015config FAULT_INJECTION
2016	bool "Fault-injection framework"
2017	depends on DEBUG_KERNEL
2018	help
2019	  Provide fault-injection framework.
2020	  For more details, see Documentation/fault-injection/.
2021
2022config FAILSLAB
2023	bool "Fault-injection capability for kmalloc"
2024	depends on FAULT_INJECTION
2025	help
2026	  Provide fault-injection capability for kmalloc.
2027
2028config FAIL_PAGE_ALLOC
2029	bool "Fault-injection capability for alloc_pages()"
2030	depends on FAULT_INJECTION
2031	help
2032	  Provide fault-injection capability for alloc_pages().
2033
2034config FAULT_INJECTION_USERCOPY
2035	bool "Fault injection capability for usercopy functions"
2036	depends on FAULT_INJECTION
2037	help
2038	  Provides fault-injection capability to inject failures
2039	  in usercopy functions (copy_from_user(), get_user(), ...).
2040
2041config FAIL_MAKE_REQUEST
2042	bool "Fault-injection capability for disk IO"
2043	depends on FAULT_INJECTION && BLOCK
2044	help
2045	  Provide fault-injection capability for disk IO.
2046
2047config FAIL_IO_TIMEOUT
2048	bool "Fault-injection capability for faking disk interrupts"
2049	depends on FAULT_INJECTION && BLOCK
2050	help
2051	  Provide fault-injection capability on end IO handling. This
2052	  will make the block layer "forget" an interrupt as configured,
2053	  thus exercising the error handling.
2054
2055	  Only works with drivers that use the generic timeout handling,
2056	  for others it won't do anything.
2057
2058config FAIL_FUTEX
2059	bool "Fault-injection capability for futexes"
2060	select DEBUG_FS
2061	depends on FAULT_INJECTION && FUTEX
2062	help
2063	  Provide fault-injection capability for futexes.
2064
2065config FAULT_INJECTION_DEBUG_FS
2066	bool "Debugfs entries for fault-injection capabilities"
2067	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2068	help
2069	  Enable configuration of fault-injection capabilities via debugfs.
2070
2071config FAIL_FUNCTION
2072	bool "Fault-injection capability for functions"
2073	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2074	help
2075	  Provide function-based fault-injection capability.
2076	  This will allow you to override a specific function with a return
2077	  with given return value. As a result, function caller will see
2078	  an error value and have to handle it. This is useful to test the
2079	  error handling in various subsystems.
2080
2081config FAIL_MMC_REQUEST
2082	bool "Fault-injection capability for MMC IO"
2083	depends on FAULT_INJECTION_DEBUG_FS && MMC
2084	help
2085	  Provide fault-injection capability for MMC IO.
2086	  This will make the mmc core return data errors. This is
2087	  useful to test the error handling in the mmc block device
2088	  and to test how the mmc host driver handles retries from
2089	  the block device.
2090
2091config FAIL_SUNRPC
2092	bool "Fault-injection capability for SunRPC"
2093	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2094	help
2095	  Provide fault-injection capability for SunRPC and
2096	  its consumers.
2097
2098config FAULT_INJECTION_CONFIGFS
2099	bool "Configfs interface for fault-injection capabilities"
2100	depends on FAULT_INJECTION
2101	select CONFIGFS_FS
2102	help
2103	  This option allows configfs-based drivers to dynamically configure
2104	  fault-injection via configfs.  Each parameter for driver-specific
2105	  fault-injection can be made visible as a configfs attribute in a
2106	  configfs group.
2107
2108
2109config FAULT_INJECTION_STACKTRACE_FILTER
2110	bool "stacktrace filter for fault-injection capabilities"
2111	depends on FAULT_INJECTION
2112	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2113	select STACKTRACE
2114	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2115	help
2116	  Provide stacktrace filter for fault-injection capabilities
2117
2118config ARCH_HAS_KCOV
2119	bool
2120	help
2121	  An architecture should select this when it can successfully
2122	  build and run with CONFIG_KCOV. This typically requires
2123	  disabling instrumentation for some early boot code.
2124
2125config CC_HAS_SANCOV_TRACE_PC
2126	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2127
2128
2129config KCOV
2130	bool "Code coverage for fuzzing"
2131	depends on ARCH_HAS_KCOV
2132	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2133	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2134		   GCC_VERSION >= 120000 || CC_IS_CLANG
2135	select DEBUG_FS
2136	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2137	select OBJTOOL if HAVE_NOINSTR_HACK
2138	help
2139	  KCOV exposes kernel code coverage information in a form suitable
2140	  for coverage-guided fuzzing (randomized testing).
2141
2142	  For more details, see Documentation/dev-tools/kcov.rst.
2143
2144config KCOV_ENABLE_COMPARISONS
2145	bool "Enable comparison operands collection by KCOV"
2146	depends on KCOV
2147	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2148	help
2149	  KCOV also exposes operands of every comparison in the instrumented
2150	  code along with operand sizes and PCs of the comparison instructions.
2151	  These operands can be used by fuzzing engines to improve the quality
2152	  of fuzzing coverage.
2153
2154config KCOV_INSTRUMENT_ALL
2155	bool "Instrument all code by default"
2156	depends on KCOV
2157	default y
2158	help
2159	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2160	  then you will want to instrument the whole kernel and you should
2161	  say y here. If you are doing more targeted fuzzing (like e.g.
2162	  filesystem fuzzing with AFL) then you will want to enable coverage
2163	  for more specific subsets of files, and should say n here.
2164
2165config KCOV_IRQ_AREA_SIZE
2166	hex "Size of interrupt coverage collection area in words"
2167	depends on KCOV
2168	default 0x40000
2169	help
2170	  KCOV uses preallocated per-cpu areas to collect coverage from
2171	  soft interrupts. This specifies the size of those areas in the
2172	  number of unsigned long words.
2173
2174menuconfig RUNTIME_TESTING_MENU
2175	bool "Runtime Testing"
2176	default y
2177
2178if RUNTIME_TESTING_MENU
2179
2180config TEST_DHRY
2181	tristate "Dhrystone benchmark test"
2182	help
2183	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2184	  calculates the number of Dhrystones per second, and the number of
2185	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2186	  by 1757 (the number of Dhrystones per second obtained on the VAX
2187	  11/780, nominally a 1 MIPS machine).
2188
2189	  To run the benchmark, it needs to be enabled explicitly, either from
2190	  the kernel command line (when built-in), or from userspace (when
2191	  built-in or modular).
2192
2193	  Run once during kernel boot:
2194
2195	      test_dhry.run
2196
2197	  Set number of iterations from kernel command line:
2198
2199	      test_dhry.iterations=<n>
2200
2201	  Set number of iterations from userspace:
2202
2203	      echo <n> > /sys/module/test_dhry/parameters/iterations
2204
2205	  Trigger manual run from userspace:
2206
2207	      echo y > /sys/module/test_dhry/parameters/run
2208
2209	  If the number of iterations is <= 0, the test will devise a suitable
2210	  number of iterations (test runs for at least 2s) automatically.
2211	  This process takes ca. 4s.
2212
2213	  If unsure, say N.
2214
2215config LKDTM
2216	tristate "Linux Kernel Dump Test Tool Module"
2217	depends on DEBUG_FS
2218	help
2219	This module enables testing of the different dumping mechanisms by
2220	inducing system failures at predefined crash points.
2221	If you don't need it: say N
2222	Choose M here to compile this code as a module. The module will be
2223	called lkdtm.
2224
2225	Documentation on how to use the module can be found in
2226	Documentation/fault-injection/provoke-crashes.rst
2227
2228config CPUMASK_KUNIT_TEST
2229	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2230	depends on KUNIT
2231	default KUNIT_ALL_TESTS
2232	help
2233	  Enable to turn on cpumask tests, running at boot or module load time.
2234
2235	  For more information on KUnit and unit tests in general, please refer
2236	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2237
2238	  If unsure, say N.
2239
2240config TEST_LIST_SORT
2241	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2242	depends on KUNIT
2243	default KUNIT_ALL_TESTS
2244	help
2245	  Enable this to turn on 'list_sort()' function test. This test is
2246	  executed only once during system boot (so affects only boot time),
2247	  or at module load time.
2248
2249	  If unsure, say N.
2250
2251config TEST_MIN_HEAP
2252	tristate "Min heap test"
2253	depends on DEBUG_KERNEL || m
2254	help
2255	  Enable this to turn on min heap function tests. This test is
2256	  executed only once during system boot (so affects only boot time),
2257	  or at module load time.
2258
2259	  If unsure, say N.
2260
2261config TEST_SORT
2262	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2263	depends on KUNIT
2264	default KUNIT_ALL_TESTS
2265	help
2266	  This option enables the self-test function of 'sort()' at boot,
2267	  or at module load time.
2268
2269	  If unsure, say N.
2270
2271config TEST_DIV64
2272	tristate "64bit/32bit division and modulo test"
2273	depends on DEBUG_KERNEL || m
2274	help
2275	  Enable this to turn on 'do_div()' function test. This test is
2276	  executed only once during system boot (so affects only boot time),
2277	  or at module load time.
2278
2279	  If unsure, say N.
2280
2281config TEST_IOV_ITER
2282	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2283	depends on KUNIT
2284	depends on MMU
2285	default KUNIT_ALL_TESTS
2286	help
2287	  Enable this to turn on testing of the operation of the I/O iterator
2288	  (iov_iter). This test is executed only once during system boot (so
2289	  affects only boot time), or at module load time.
2290
2291	  If unsure, say N.
2292
2293config KPROBES_SANITY_TEST
2294	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2295	depends on DEBUG_KERNEL
2296	depends on KPROBES
2297	depends on KUNIT
2298	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2299	default KUNIT_ALL_TESTS
2300	help
2301	  This option provides for testing basic kprobes functionality on
2302	  boot. Samples of kprobe and kretprobe are inserted and
2303	  verified for functionality.
2304
2305	  Say N if you are unsure.
2306
2307config FPROBE_SANITY_TEST
2308	bool "Self test for fprobe"
2309	depends on DEBUG_KERNEL
2310	depends on FPROBE
2311	depends on KUNIT=y
2312	help
2313	  This option will enable testing the fprobe when the system boot.
2314	  A series of tests are made to verify that the fprobe is functioning
2315	  properly.
2316
2317	  Say N if you are unsure.
2318
2319config BACKTRACE_SELF_TEST
2320	tristate "Self test for the backtrace code"
2321	depends on DEBUG_KERNEL
2322	help
2323	  This option provides a kernel module that can be used to test
2324	  the kernel stack backtrace code. This option is not useful
2325	  for distributions or general kernels, but only for kernel
2326	  developers working on architecture code.
2327
2328	  Note that if you want to also test saved backtraces, you will
2329	  have to enable STACKTRACE as well.
2330
2331	  Say N if you are unsure.
2332
2333config TEST_REF_TRACKER
2334	tristate "Self test for reference tracker"
2335	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2336	select REF_TRACKER
2337	help
2338	  This option provides a kernel module performing tests
2339	  using reference tracker infrastructure.
2340
2341	  Say N if you are unsure.
2342
2343config RBTREE_TEST
2344	tristate "Red-Black tree test"
2345	depends on DEBUG_KERNEL
2346	help
2347	  A benchmark measuring the performance of the rbtree library.
2348	  Also includes rbtree invariant checks.
2349
2350config REED_SOLOMON_TEST
2351	tristate "Reed-Solomon library test"
2352	depends on DEBUG_KERNEL || m
2353	select REED_SOLOMON
2354	select REED_SOLOMON_ENC16
2355	select REED_SOLOMON_DEC16
2356	help
2357	  This option enables the self-test function of rslib at boot,
2358	  or at module load time.
2359
2360	  If unsure, say N.
2361
2362config INTERVAL_TREE_TEST
2363	tristate "Interval tree test"
2364	depends on DEBUG_KERNEL
2365	select INTERVAL_TREE
2366	help
2367	  A benchmark measuring the performance of the interval tree library
2368
2369config PERCPU_TEST
2370	tristate "Per cpu operations test"
2371	depends on m && DEBUG_KERNEL
2372	help
2373	  Enable this option to build test module which validates per-cpu
2374	  operations.
2375
2376	  If unsure, say N.
2377
2378config ATOMIC64_SELFTEST
2379	tristate "Perform an atomic64_t self-test"
2380	help
2381	  Enable this option to test the atomic64_t functions at boot or
2382	  at module load time.
2383
2384	  If unsure, say N.
2385
2386config ASYNC_RAID6_TEST
2387	tristate "Self test for hardware accelerated raid6 recovery"
2388	depends on ASYNC_RAID6_RECOV
2389	select ASYNC_MEMCPY
2390	help
2391	  This is a one-shot self test that permutes through the
2392	  recovery of all the possible two disk failure scenarios for a
2393	  N-disk array.  Recovery is performed with the asynchronous
2394	  raid6 recovery routines, and will optionally use an offload
2395	  engine if one is available.
2396
2397	  If unsure, say N.
2398
2399config TEST_HEXDUMP
2400	tristate "Test functions located in the hexdump module at runtime"
2401
2402config STRING_KUNIT_TEST
2403	tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
2404	depends on KUNIT
2405	default KUNIT_ALL_TESTS
2406
2407config STRING_HELPERS_KUNIT_TEST
2408	tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
2409	depends on KUNIT
2410	default KUNIT_ALL_TESTS
2411
2412config TEST_KSTRTOX
2413	tristate "Test kstrto*() family of functions at runtime"
2414
2415config TEST_PRINTF
2416	tristate "Test printf() family of functions at runtime"
2417
2418config TEST_SCANF
2419	tristate "Test scanf() family of functions at runtime"
2420
2421config TEST_BITMAP
2422	tristate "Test bitmap_*() family of functions at runtime"
2423	help
2424	  Enable this option to test the bitmap functions at boot.
2425
2426	  If unsure, say N.
2427
2428config TEST_UUID
2429	tristate "Test functions located in the uuid module at runtime"
2430
2431config TEST_XARRAY
2432	tristate "Test the XArray code at runtime"
2433
2434config TEST_MAPLE_TREE
2435	tristate "Test the Maple Tree code at runtime or module load"
2436	help
2437	  Enable this option to test the maple tree code functions at boot, or
2438	  when the module is loaded. Enable "Debug Maple Trees" will enable
2439	  more verbose output on failures.
2440
2441	  If unsure, say N.
2442
2443config TEST_RHASHTABLE
2444	tristate "Perform selftest on resizable hash table"
2445	help
2446	  Enable this option to test the rhashtable functions at boot.
2447
2448	  If unsure, say N.
2449
2450config TEST_IDA
2451	tristate "Perform selftest on IDA functions"
2452
2453config TEST_PARMAN
2454	tristate "Perform selftest on priority array manager"
2455	depends on PARMAN
2456	help
2457	  Enable this option to test priority array manager on boot
2458	  (or module load).
2459
2460	  If unsure, say N.
2461
2462config TEST_IRQ_TIMINGS
2463	bool "IRQ timings selftest"
2464	depends on IRQ_TIMINGS
2465	help
2466	  Enable this option to test the irq timings code on boot.
2467
2468	  If unsure, say N.
2469
2470config TEST_LKM
2471	tristate "Test module loading with 'hello world' module"
2472	depends on m
2473	help
2474	  This builds the "test_module" module that emits "Hello, world"
2475	  on printk when loaded. It is designed to be used for basic
2476	  evaluation of the module loading subsystem (for example when
2477	  validating module verification). It lacks any extra dependencies,
2478	  and will not normally be loaded by the system unless explicitly
2479	  requested by name.
2480
2481	  If unsure, say N.
2482
2483config TEST_BITOPS
2484	tristate "Test module for compilation of bitops operations"
2485	help
2486	  This builds the "test_bitops" module that is much like the
2487	  TEST_LKM module except that it does a basic exercise of the
2488	  set/clear_bit macros and get_count_order/long to make sure there are
2489	  no compiler warnings from C=1 sparse checker or -Wextra
2490	  compilations. It has no dependencies and doesn't run or load unless
2491	  explicitly requested by name.  for example: modprobe test_bitops.
2492
2493	  If unsure, say N.
2494
2495config TEST_VMALLOC
2496	tristate "Test module for stress/performance analysis of vmalloc allocator"
2497	default n
2498       depends on MMU
2499	depends on m
2500	help
2501	  This builds the "test_vmalloc" module that should be used for
2502	  stress and performance analysis. So, any new change for vmalloc
2503	  subsystem can be evaluated from performance and stability point
2504	  of view.
2505
2506	  If unsure, say N.
2507
2508config TEST_USER_COPY
2509	tristate "Test user/kernel boundary protections"
2510	depends on m
2511	help
2512	  This builds the "test_user_copy" module that runs sanity checks
2513	  on the copy_to/from_user infrastructure, making sure basic
2514	  user/kernel boundary testing is working. If it fails to load,
2515	  a regression has been detected in the user/kernel memory boundary
2516	  protections.
2517
2518	  If unsure, say N.
2519
2520config TEST_BPF
2521	tristate "Test BPF filter functionality"
2522	depends on m && NET
2523	help
2524	  This builds the "test_bpf" module that runs various test vectors
2525	  against the BPF interpreter or BPF JIT compiler depending on the
2526	  current setting. This is in particular useful for BPF JIT compiler
2527	  development, but also to run regression tests against changes in
2528	  the interpreter code. It also enables test stubs for eBPF maps and
2529	  verifier used by user space verifier testsuite.
2530
2531	  If unsure, say N.
2532
2533config TEST_BLACKHOLE_DEV
2534	tristate "Test blackhole netdev functionality"
2535	depends on m && NET
2536	help
2537	  This builds the "test_blackhole_dev" module that validates the
2538	  data path through this blackhole netdev.
2539
2540	  If unsure, say N.
2541
2542config FIND_BIT_BENCHMARK
2543	tristate "Test find_bit functions"
2544	help
2545	  This builds the "test_find_bit" module that measure find_*_bit()
2546	  functions performance.
2547
2548	  If unsure, say N.
2549
2550config TEST_FIRMWARE
2551	tristate "Test firmware loading via userspace interface"
2552	depends on FW_LOADER
2553	help
2554	  This builds the "test_firmware" module that creates a userspace
2555	  interface for testing firmware loading. This can be used to
2556	  control the triggering of firmware loading without needing an
2557	  actual firmware-using device. The contents can be rechecked by
2558	  userspace.
2559
2560	  If unsure, say N.
2561
2562config TEST_SYSCTL
2563	tristate "sysctl test driver"
2564	depends on PROC_SYSCTL
2565	help
2566	  This builds the "test_sysctl" module. This driver enables to test the
2567	  proc sysctl interfaces available to drivers safely without affecting
2568	  production knobs which might alter system functionality.
2569
2570	  If unsure, say N.
2571
2572config BITFIELD_KUNIT
2573	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2574	depends on KUNIT
2575	default KUNIT_ALL_TESTS
2576	help
2577	  Enable this option to test the bitfield functions at boot.
2578
2579	  KUnit tests run during boot and output the results to the debug log
2580	  in TAP format (http://testanything.org/). Only useful for kernel devs
2581	  running the KUnit test harness, and not intended for inclusion into a
2582	  production build.
2583
2584	  For more information on KUnit and unit tests in general please refer
2585	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2586
2587	  If unsure, say N.
2588
2589config CHECKSUM_KUNIT
2590	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2591	depends on KUNIT
2592	default KUNIT_ALL_TESTS
2593	help
2594	  Enable this option to test the checksum functions at boot.
2595
2596	  KUnit tests run during boot and output the results to the debug log
2597	  in TAP format (http://testanything.org/). Only useful for kernel devs
2598	  running the KUnit test harness, and not intended for inclusion into a
2599	  production build.
2600
2601	  For more information on KUnit and unit tests in general please refer
2602	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2603
2604	  If unsure, say N.
2605
2606config HASH_KUNIT_TEST
2607	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2608	depends on KUNIT
2609	default KUNIT_ALL_TESTS
2610	help
2611	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2612	  integer (<linux/hash.h>) hash functions on boot.
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	  This is intended to help people writing architecture-specific
2623	  optimized versions. If unsure, say N.
2624
2625config RESOURCE_KUNIT_TEST
2626	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2627	depends on KUNIT
2628	default KUNIT_ALL_TESTS
2629	help
2630	  This builds the resource API unit test.
2631	  Tests the logic of API provided by resource.c and ioport.h.
2632	  For more information on KUnit and unit tests in general please refer
2633	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2634
2635	  If unsure, say N.
2636
2637config SYSCTL_KUNIT_TEST
2638	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2639	depends on KUNIT
2640	default KUNIT_ALL_TESTS
2641	help
2642	  This builds the proc sysctl unit test, which runs on boot.
2643	  Tests the API contract and implementation correctness of sysctl.
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 LIST_KUNIT_TEST
2650	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2651	depends on KUNIT
2652	default KUNIT_ALL_TESTS
2653	help
2654	  This builds the linked list KUnit test suite.
2655	  It tests that the API and basic functionality of the list_head type
2656	  and associated macros.
2657
2658	  KUnit tests run during boot and output the results to the debug log
2659	  in TAP format (https://testanything.org/). Only useful for kernel devs
2660	  running the KUnit test harness, and not intended for inclusion into a
2661	  production build.
2662
2663	  For more information on KUnit and unit tests in general please refer
2664	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2665
2666	  If unsure, say N.
2667
2668config HASHTABLE_KUNIT_TEST
2669	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2670	depends on KUNIT
2671	default KUNIT_ALL_TESTS
2672	help
2673	  This builds the hashtable KUnit test suite.
2674	  It tests the basic functionality of the API defined in
2675	  include/linux/hashtable.h. For more information on KUnit and
2676	  unit tests in general please refer to the KUnit documentation
2677	  in Documentation/dev-tools/kunit/.
2678
2679	  If unsure, say N.
2680
2681config LINEAR_RANGES_TEST
2682	tristate "KUnit test for linear_ranges"
2683	depends on KUNIT
2684	select LINEAR_RANGES
2685	help
2686	  This builds the linear_ranges unit test, which runs on boot.
2687	  Tests the linear_ranges logic correctness.
2688	  For more information on KUnit and unit tests in general please refer
2689	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2690
2691	  If unsure, say N.
2692
2693config CMDLINE_KUNIT_TEST
2694	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2695	depends on KUNIT
2696	default KUNIT_ALL_TESTS
2697	help
2698	  This builds the cmdline API unit test.
2699	  Tests the logic of API provided by cmdline.c.
2700	  For more information on KUnit and unit tests in general please refer
2701	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2702
2703	  If unsure, say N.
2704
2705config BITS_TEST
2706	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2707	depends on KUNIT
2708	default KUNIT_ALL_TESTS
2709	help
2710	  This builds the bits unit test.
2711	  Tests the logic of macros defined in bits.h.
2712	  For more information on KUnit and unit tests in general please refer
2713	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2714
2715	  If unsure, say N.
2716
2717config SLUB_KUNIT_TEST
2718	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2719	depends on SLUB_DEBUG && KUNIT
2720	default KUNIT_ALL_TESTS
2721	help
2722	  This builds SLUB allocator unit test.
2723	  Tests SLUB cache debugging functionality.
2724	  For more information on KUnit and unit tests in general please refer
2725	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2726
2727	  If unsure, say N.
2728
2729config RATIONAL_KUNIT_TEST
2730	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2731	depends on KUNIT && RATIONAL
2732	default KUNIT_ALL_TESTS
2733	help
2734	  This builds the rational math unit test.
2735	  For more information on KUnit and unit tests in general please refer
2736	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2737
2738	  If unsure, say N.
2739
2740config MEMCPY_KUNIT_TEST
2741	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2742	depends on KUNIT
2743	default KUNIT_ALL_TESTS
2744	help
2745	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2746	  For more information on KUnit and unit tests in general please refer
2747	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2748
2749	  If unsure, say N.
2750
2751config IS_SIGNED_TYPE_KUNIT_TEST
2752	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2753	depends on KUNIT
2754	default KUNIT_ALL_TESTS
2755	help
2756	  Builds unit tests for the is_signed_type() macro.
2757
2758	  For more information on KUnit and unit tests in general please refer
2759	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2760
2761	  If unsure, say N.
2762
2763config OVERFLOW_KUNIT_TEST
2764	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2765	depends on KUNIT
2766	default KUNIT_ALL_TESTS
2767	help
2768	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2769	  related functions.
2770
2771	  For more information on KUnit and unit tests in general please refer
2772	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2773
2774	  If unsure, say N.
2775
2776config STACKINIT_KUNIT_TEST
2777	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2778	depends on KUNIT
2779	default KUNIT_ALL_TESTS
2780	help
2781	  Test if the kernel is zero-initializing stack variables and
2782	  padding. Coverage is controlled by compiler flags,
2783	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2784	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2785	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2786
2787config FORTIFY_KUNIT_TEST
2788	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2789	depends on KUNIT
2790	default KUNIT_ALL_TESTS
2791	help
2792	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2793	  by the str*() and mem*() family of functions. For testing runtime
2794	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2795
2796config HW_BREAKPOINT_KUNIT_TEST
2797	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2798	depends on HAVE_HW_BREAKPOINT
2799	depends on KUNIT=y
2800	default KUNIT_ALL_TESTS
2801	help
2802	  Tests for hw_breakpoint constraints accounting.
2803
2804	  If unsure, say N.
2805
2806config SIPHASH_KUNIT_TEST
2807	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2808	depends on KUNIT
2809	default KUNIT_ALL_TESTS
2810	help
2811	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2812	  functions on boot (or module load).
2813
2814	  This is intended to help people writing architecture-specific
2815	  optimized versions.  If unsure, say N.
2816
2817config TEST_UDELAY
2818	tristate "udelay test driver"
2819	help
2820	  This builds the "udelay_test" module that helps to make sure
2821	  that udelay() is working properly.
2822
2823	  If unsure, say N.
2824
2825config TEST_STATIC_KEYS
2826	tristate "Test static keys"
2827	depends on m
2828	help
2829	  Test the static key interfaces.
2830
2831	  If unsure, say N.
2832
2833config TEST_DYNAMIC_DEBUG
2834	tristate "Test DYNAMIC_DEBUG"
2835	depends on DYNAMIC_DEBUG
2836	help
2837	  This module registers a tracer callback to count enabled
2838	  pr_debugs in a 'do_debugging' function, then alters their
2839	  enablements, calls the function, and compares counts.
2840
2841	  If unsure, say N.
2842
2843config TEST_KMOD
2844	tristate "kmod stress tester"
2845	depends on m
2846	depends on NETDEVICES && NET_CORE && INET # for TUN
2847	depends on BLOCK
2848	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2849	select TEST_LKM
2850	select XFS_FS
2851	select TUN
2852	select BTRFS_FS
2853	help
2854	  Test the kernel's module loading mechanism: kmod. kmod implements
2855	  support to load modules using the Linux kernel's usermode helper.
2856	  This test provides a series of tests against kmod.
2857
2858	  Although technically you can either build test_kmod as a module or
2859	  into the kernel we disallow building it into the kernel since
2860	  it stress tests request_module() and this will very likely cause
2861	  some issues by taking over precious threads available from other
2862	  module load requests, ultimately this could be fatal.
2863
2864	  To run tests run:
2865
2866	  tools/testing/selftests/kmod/kmod.sh --help
2867
2868	  If unsure, say N.
2869
2870config TEST_DEBUG_VIRTUAL
2871	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2872	depends on DEBUG_VIRTUAL
2873	help
2874	  Test the kernel's ability to detect incorrect calls to
2875	  virt_to_phys() done against the non-linear part of the
2876	  kernel's virtual address map.
2877
2878	  If unsure, say N.
2879
2880config TEST_MEMCAT_P
2881	tristate "Test memcat_p() helper function"
2882	help
2883	  Test the memcat_p() helper for correctly merging two
2884	  pointer arrays together.
2885
2886	  If unsure, say N.
2887
2888config TEST_OBJAGG
2889	tristate "Perform selftest on object aggreration manager"
2890	default n
2891	depends on OBJAGG
2892	help
2893	  Enable this option to test object aggregation manager on boot
2894	  (or module load).
2895
2896config TEST_MEMINIT
2897	tristate "Test heap/page initialization"
2898	help
2899	  Test if the kernel is zero-initializing heap and page allocations.
2900	  This can be useful to test init_on_alloc and init_on_free features.
2901
2902	  If unsure, say N.
2903
2904config TEST_HMM
2905	tristate "Test HMM (Heterogeneous Memory Management)"
2906	depends on TRANSPARENT_HUGEPAGE
2907	depends on DEVICE_PRIVATE
2908	select HMM_MIRROR
2909	select MMU_NOTIFIER
2910	help
2911	  This is a pseudo device driver solely for testing HMM.
2912	  Say M here if you want to build the HMM test module.
2913	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2914
2915	  If unsure, say N.
2916
2917config TEST_FREE_PAGES
2918	tristate "Test freeing pages"
2919	help
2920	  Test that a memory leak does not occur due to a race between
2921	  freeing a block of pages and a speculative page reference.
2922	  Loading this module is safe if your kernel has the bug fixed.
2923	  If the bug is not fixed, it will leak gigabytes of memory and
2924	  probably OOM your system.
2925
2926config TEST_FPU
2927	tristate "Test floating point operations in kernel space"
2928	depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL
2929	help
2930	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2931	  which will trigger a sequence of floating point operations. This is used
2932	  for self-testing floating point control register setting in
2933	  kernel_fpu_begin().
2934
2935	  If unsure, say N.
2936
2937config TEST_CLOCKSOURCE_WATCHDOG
2938	tristate "Test clocksource watchdog in kernel space"
2939	depends on CLOCKSOURCE_WATCHDOG
2940	help
2941	  Enable this option to create a kernel module that will trigger
2942	  a test of the clocksource watchdog.  This module may be loaded
2943	  via modprobe or insmod in which case it will run upon being
2944	  loaded, or it may be built in, in which case it will run
2945	  shortly after boot.
2946
2947	  If unsure, say N.
2948
2949config TEST_OBJPOOL
2950	tristate "Test module for correctness and stress of objpool"
2951	default n
2952	depends on m && DEBUG_KERNEL
2953	help
2954	  This builds the "test_objpool" module that should be used for
2955	  correctness verification and concurrent testings of objects
2956	  allocation and reclamation.
2957
2958	  If unsure, say N.
2959
2960endif # RUNTIME_TESTING_MENU
2961
2962config ARCH_USE_MEMTEST
2963	bool
2964	help
2965	  An architecture should select this when it uses early_memtest()
2966	  during boot process.
2967
2968config MEMTEST
2969	bool "Memtest"
2970	depends on ARCH_USE_MEMTEST
2971	help
2972	  This option adds a kernel parameter 'memtest', which allows memtest
2973	  to be set and executed.
2974	        memtest=0, mean disabled; -- default
2975	        memtest=1, mean do 1 test pattern;
2976	        ...
2977	        memtest=17, mean do 17 test patterns.
2978	  If you are unsure how to answer this question, answer N.
2979
2980
2981
2982config HYPERV_TESTING
2983	bool "Microsoft Hyper-V driver testing"
2984	default n
2985	depends on HYPERV && DEBUG_FS
2986	help
2987	  Select this option to enable Hyper-V vmbus testing.
2988
2989endmenu # "Kernel Testing and Coverage"
2990
2991menu "Rust hacking"
2992
2993config RUST_DEBUG_ASSERTIONS
2994	bool "Debug assertions"
2995	depends on RUST
2996	help
2997	  Enables rustc's `-Cdebug-assertions` codegen option.
2998
2999	  This flag lets you turn `cfg(debug_assertions)` conditional
3000	  compilation on or off. This can be used to enable extra debugging
3001	  code in development but not in production. For example, it controls
3002	  the behavior of the standard library's `debug_assert!` macro.
3003
3004	  Note that this will apply to all Rust code, including `core`.
3005
3006	  If unsure, say N.
3007
3008config RUST_OVERFLOW_CHECKS
3009	bool "Overflow checks"
3010	default y
3011	depends on RUST
3012	help
3013	  Enables rustc's `-Coverflow-checks` codegen option.
3014
3015	  This flag allows you to control the behavior of runtime integer
3016	  overflow. When overflow-checks are enabled, a Rust panic will occur
3017	  on overflow.
3018
3019	  Note that this will apply to all Rust code, including `core`.
3020
3021	  If unsure, say Y.
3022
3023config RUST_BUILD_ASSERT_ALLOW
3024	bool "Allow unoptimized build-time assertions"
3025	depends on RUST
3026	help
3027	  Controls how are `build_error!` and `build_assert!` handled during build.
3028
3029	  If calls to them exist in the binary, it may indicate a violated invariant
3030	  or that the optimizer failed to verify the invariant during compilation.
3031
3032	  This should not happen, thus by default the build is aborted. However,
3033	  as an escape hatch, you can choose Y here to ignore them during build
3034	  and let the check be carried at runtime (with `panic!` being called if
3035	  the check fails).
3036
3037	  If unsure, say N.
3038
3039config RUST_KERNEL_DOCTESTS
3040	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3041	depends on RUST && KUNIT=y
3042	default KUNIT_ALL_TESTS
3043	help
3044	  This builds the documentation tests of the `kernel` crate
3045	  as KUnit tests.
3046
3047	  For more information on KUnit and unit tests in general,
3048	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3049
3050	  If unsure, say N.
3051
3052endmenu # "Rust"
3053
3054endmenu # Kernel hacking
3055