xref: /linux/lib/Kconfig.debug (revision 5c2e7736e20d9b348a44cafbfa639fe2653fbc34)
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 jiffy" 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 PAHOLE_VERSION >= 116
383	depends on DEBUG_INFO_DWARF4 || PAHOLE_VERSION >= 121
384	# pahole uses elfutils, which does not have support for Hexagon relocations
385	depends on !HEXAGON
386	help
387	  Generate deduplicated BTF type information from DWARF debug info.
388	  Turning this on requires pahole v1.16 or later (v1.21 or later to
389	  support DWARF 5), which will convert DWARF type info into equivalent
390	  deduplicated BTF type info.
391
392config PAHOLE_HAS_SPLIT_BTF
393	def_bool PAHOLE_VERSION >= 119
394
395config PAHOLE_HAS_BTF_TAG
396	def_bool PAHOLE_VERSION >= 123
397	depends on CC_IS_CLANG
398	help
399	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
400	  btf_decl_tag) or not. Currently only clang compiler implements
401	  these attributes, so make the config depend on CC_IS_CLANG.
402
403config PAHOLE_HAS_LANG_EXCLUDE
404	def_bool PAHOLE_VERSION >= 124
405	help
406	  Support for the --lang_exclude flag which makes pahole exclude
407	  compilation units from the supplied language. Used in Kbuild to
408	  omit Rust CUs which are not supported in version 1.24 of pahole,
409	  otherwise it would emit malformed kernel and module binaries when
410	  using DEBUG_INFO_BTF_MODULES.
411
412config DEBUG_INFO_BTF_MODULES
413	bool "Generate BTF type information for kernel modules"
414	default y
415	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
416	help
417	  Generate compact split BTF type information for kernel modules.
418
419config MODULE_ALLOW_BTF_MISMATCH
420	bool "Allow loading modules with non-matching BTF type info"
421	depends on DEBUG_INFO_BTF_MODULES
422	help
423	  For modules whose split BTF does not match vmlinux, load without
424	  BTF rather than refusing to load. The default behavior with
425	  module BTF enabled is to reject modules with such mismatches;
426	  this option will still load module BTF where possible but ignore
427	  it when a mismatch is found.
428
429config GDB_SCRIPTS
430	bool "Provide GDB scripts for kernel debugging"
431	help
432	  This creates the required links to GDB helper scripts in the
433	  build directory. If you load vmlinux into gdb, the helper
434	  scripts will be automatically imported by gdb as well, and
435	  additional functions are available to analyze a Linux kernel
436	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
437	  for further details.
438
439endif # DEBUG_INFO
440
441config FRAME_WARN
442	int "Warn for stack frames larger than"
443	range 0 8192
444	default 0 if KMSAN
445	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
446	default 2048 if PARISC
447	default 1536 if (!64BIT && XTENSA)
448	default 1280 if KASAN && !64BIT
449	default 1024 if !64BIT
450	default 2048 if 64BIT
451	help
452	  Tell the compiler to warn at build time for stack frames larger than this.
453	  Setting this too low will cause a lot of warnings.
454	  Setting it to 0 disables the warning.
455
456config STRIP_ASM_SYMS
457	bool "Strip assembler-generated symbols during link"
458	default n
459	help
460	  Strip internal assembler-generated symbols during a link (symbols
461	  that look like '.Lxxx') so they don't pollute the output of
462	  get_wchan() and suchlike.
463
464config READABLE_ASM
465	bool "Generate readable assembler code"
466	depends on DEBUG_KERNEL
467	depends on CC_IS_GCC
468	help
469	  Disable some compiler optimizations that tend to generate human unreadable
470	  assembler output. This may make the kernel slightly slower, but it helps
471	  to keep kernel developers who have to stare a lot at assembler listings
472	  sane.
473
474config HEADERS_INSTALL
475	bool "Install uapi headers to usr/include"
476	depends on !UML
477	help
478	  This option will install uapi headers (headers exported to user-space)
479	  into the usr/include directory for use during the kernel build.
480	  This is unneeded for building the kernel itself, but needed for some
481	  user-space program samples. It is also needed by some features such
482	  as uapi header sanity checks.
483
484config DEBUG_SECTION_MISMATCH
485	bool "Enable full Section mismatch analysis"
486	depends on CC_IS_GCC
487	help
488	  The section mismatch analysis checks if there are illegal
489	  references from one section to another section.
490	  During linktime or runtime, some sections are dropped;
491	  any use of code/data previously in these sections would
492	  most likely result in an oops.
493	  In the code, functions and variables are annotated with
494	  __init,, etc. (see the full list in include/linux/init.h),
495	  which results in the code/data being placed in specific sections.
496	  The section mismatch analysis is always performed after a full
497	  kernel build, and enabling this option causes the following
498	  additional step to occur:
499	  - Add the option -fno-inline-functions-called-once to gcc commands.
500	    When inlining a function annotated with __init in a non-init
501	    function, we would lose the section information and thus
502	    the analysis would not catch the illegal reference.
503	    This option tells gcc to inline less (but it does result in
504	    a larger kernel).
505
506config SECTION_MISMATCH_WARN_ONLY
507	bool "Make section mismatch errors non-fatal"
508	default y
509	help
510	  If you say N here, the build process will fail if there are any
511	  section mismatch, instead of just throwing warnings.
512
513	  If unsure, say Y.
514
515config DEBUG_FORCE_FUNCTION_ALIGN_64B
516	bool "Force all function address 64B aligned"
517	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
518	select FUNCTION_ALIGNMENT_64B
519	help
520	  There are cases that a commit from one domain changes the function
521	  address alignment of other domains, and cause magic performance
522	  bump (regression or improvement). Enable this option will help to
523	  verify if the bump is caused by function alignment changes, while
524	  it will slightly increase the kernel size and affect icache usage.
525
526	  It is mainly for debug and performance tuning use.
527
528#
529# Select this config option from the architecture Kconfig, if it
530# is preferred to always offer frame pointers as a config
531# option on the architecture (regardless of KERNEL_DEBUG):
532#
533config ARCH_WANT_FRAME_POINTERS
534	bool
535
536config FRAME_POINTER
537	bool "Compile the kernel with frame pointers"
538	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
539	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
540	help
541	  If you say Y here the resulting kernel image will be slightly
542	  larger and slower, but it gives very useful debugging information
543	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
544
545config OBJTOOL
546	bool
547
548config STACK_VALIDATION
549	bool "Compile-time stack metadata validation"
550	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
551	select OBJTOOL
552	default n
553	help
554	  Validate frame pointer rules at compile-time.  This helps ensure that
555	  runtime stack traces are more reliable.
556
557	  For more information, see
558	  tools/objtool/Documentation/objtool.txt.
559
560config NOINSTR_VALIDATION
561	bool
562	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
563	select OBJTOOL
564	default y
565
566config VMLINUX_MAP
567	bool "Generate vmlinux.map file when linking"
568	depends on EXPERT
569	help
570	  Selecting this option will pass "-Map=vmlinux.map" to ld
571	  when linking vmlinux. That file can be useful for verifying
572	  and debugging magic section games, and for seeing which
573	  pieces of code get eliminated with
574	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
575
576config BUILTIN_MODULE_RANGES
577	bool "Generate address range information for builtin modules"
578	depends on !LTO
579	depends on VMLINUX_MAP
580	help
581	 When modules are built into the kernel, there will be no module name
582	 associated with its symbols in /proc/kallsyms.  Tracers may want to
583	 identify symbols by module name and symbol name regardless of whether
584	 the module is configured as loadable or not.
585
586	 This option generates modules.builtin.ranges in the build tree with
587	 offset ranges (per ELF section) for the module(s) they belong to.
588	 It also records an anchor symbol to determine the load address of the
589	 section.
590
591config DEBUG_FORCE_WEAK_PER_CPU
592	bool "Force weak per-cpu definitions"
593	depends on DEBUG_KERNEL
594	help
595	  s390 and alpha require percpu variables in modules to be
596	  defined weak to work around addressing range issue which
597	  puts the following two restrictions on percpu variable
598	  definitions.
599
600	  1. percpu symbols must be unique whether static or not
601	  2. percpu variables can't be defined inside a function
602
603	  To ensure that generic code follows the above rules, this
604	  option forces all percpu variables to be defined as weak.
605
606endmenu # "Compiler options"
607
608menu "Generic Kernel Debugging Instruments"
609
610config MAGIC_SYSRQ
611	bool "Magic SysRq key"
612	depends on !UML
613	help
614	  If you say Y here, you will have some control over the system even
615	  if the system crashes for example during kernel debugging (e.g., you
616	  will be able to flush the buffer cache to disk, reboot the system
617	  immediately or dump some status information). This is accomplished
618	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
619	  also works on a serial console (on PC hardware at least), if you
620	  send a BREAK and then within 5 seconds a command keypress. The
621	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
622	  Don't say Y unless you really know what this hack does.
623
624config MAGIC_SYSRQ_DEFAULT_ENABLE
625	hex "Enable magic SysRq key functions by default"
626	depends on MAGIC_SYSRQ
627	default 0x1
628	help
629	  Specifies which SysRq key functions are enabled by default.
630	  This may be set to 1 or 0 to enable or disable them all, or
631	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
632
633config MAGIC_SYSRQ_SERIAL
634	bool "Enable magic SysRq key over serial"
635	depends on MAGIC_SYSRQ
636	default y
637	help
638	  Many embedded boards have a disconnected TTL level serial which can
639	  generate some garbage that can lead to spurious false sysrq detects.
640	  This option allows you to decide whether you want to enable the
641	  magic SysRq key.
642
643config MAGIC_SYSRQ_SERIAL_SEQUENCE
644	string "Char sequence that enables magic SysRq over serial"
645	depends on MAGIC_SYSRQ_SERIAL
646	default ""
647	help
648	  Specifies a sequence of characters that can follow BREAK to enable
649	  SysRq on a serial console.
650
651	  If unsure, leave an empty string and the option will not be enabled.
652
653config DEBUG_FS
654	bool "Debug Filesystem"
655	help
656	  debugfs is a virtual file system that kernel developers use to put
657	  debugging files into.  Enable this option to be able to read and
658	  write to these files.
659
660	  For detailed documentation on the debugfs API, see
661	  Documentation/filesystems/.
662
663	  If unsure, say N.
664
665choice
666	prompt "Debugfs default access"
667	depends on DEBUG_FS
668	default DEBUG_FS_ALLOW_ALL
669	help
670	  This selects the default access restrictions for debugfs.
671	  It can be overridden with kernel command line option
672	  debugfs=[on,no-mount,off]. The restrictions apply for API access
673	  and filesystem registration.
674
675config DEBUG_FS_ALLOW_ALL
676	bool "Access normal"
677	help
678	  No restrictions apply. Both API and filesystem registration
679	  is on. This is the normal default operation.
680
681config DEBUG_FS_DISALLOW_MOUNT
682	bool "Do not register debugfs as filesystem"
683	help
684	  The API is open but filesystem is not loaded. Clients can still do
685	  their work and read with debug tools that do not need
686	  debugfs filesystem.
687
688config DEBUG_FS_ALLOW_NONE
689	bool "No access"
690	help
691	  Access is off. Clients get -PERM when trying to create nodes in
692	  debugfs tree and debugfs is not registered as a filesystem.
693	  Client can then back-off or continue without debugfs access.
694
695endchoice
696
697source "lib/Kconfig.kgdb"
698source "lib/Kconfig.ubsan"
699source "lib/Kconfig.kcsan"
700
701endmenu
702
703menu "Networking Debugging"
704
705source "net/Kconfig.debug"
706
707endmenu # "Networking Debugging"
708
709menu "Memory Debugging"
710
711source "mm/Kconfig.debug"
712
713config DEBUG_OBJECTS
714	bool "Debug object operations"
715	depends on DEBUG_KERNEL
716	help
717	  If you say Y here, additional code will be inserted into the
718	  kernel to track the life time of various objects and validate
719	  the operations on those objects.
720
721config DEBUG_OBJECTS_SELFTEST
722	bool "Debug objects selftest"
723	depends on DEBUG_OBJECTS
724	help
725	  This enables the selftest of the object debug code.
726
727config DEBUG_OBJECTS_FREE
728	bool "Debug objects in freed memory"
729	depends on DEBUG_OBJECTS
730	help
731	  This enables checks whether a k/v free operation frees an area
732	  which contains an object which has not been deactivated
733	  properly. This can make kmalloc/kfree-intensive workloads
734	  much slower.
735
736config DEBUG_OBJECTS_TIMERS
737	bool "Debug timer objects"
738	depends on DEBUG_OBJECTS
739	help
740	  If you say Y here, additional code will be inserted into the
741	  timer routines to track the life time of timer objects and
742	  validate the timer operations.
743
744config DEBUG_OBJECTS_WORK
745	bool "Debug work objects"
746	depends on DEBUG_OBJECTS
747	help
748	  If you say Y here, additional code will be inserted into the
749	  work queue routines to track the life time of work objects and
750	  validate the work operations.
751
752config DEBUG_OBJECTS_RCU_HEAD
753	bool "Debug RCU callbacks objects"
754	depends on DEBUG_OBJECTS
755	help
756	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
757
758config DEBUG_OBJECTS_PERCPU_COUNTER
759	bool "Debug percpu counter objects"
760	depends on DEBUG_OBJECTS
761	help
762	  If you say Y here, additional code will be inserted into the
763	  percpu counter routines to track the life time of percpu counter
764	  objects and validate the percpu counter operations.
765
766config DEBUG_OBJECTS_ENABLE_DEFAULT
767	int "debug_objects bootup default value (0-1)"
768	range 0 1
769	default "1"
770	depends on DEBUG_OBJECTS
771	help
772	  Debug objects boot parameter default value
773
774config SHRINKER_DEBUG
775	bool "Enable shrinker debugging support"
776	depends on DEBUG_FS
777	help
778	  Say Y to enable the shrinker debugfs interface which provides
779	  visibility into the kernel memory shrinkers subsystem.
780	  Disable it to avoid an extra memory footprint.
781
782config DEBUG_STACK_USAGE
783	bool "Stack utilization instrumentation"
784	depends on DEBUG_KERNEL
785	help
786	  Enables the display of the minimum amount of free stack which each
787	  task has ever had available in the sysrq-T and sysrq-P debug output.
788	  Also emits a message to dmesg when a process exits if that process
789	  used more stack space than previously exiting processes.
790
791	  This option will slow down process creation somewhat.
792
793config SCHED_STACK_END_CHECK
794	bool "Detect stack corruption on calls to schedule()"
795	depends on DEBUG_KERNEL
796	default n
797	help
798	  This option checks for a stack overrun on calls to schedule().
799	  If the stack end location is found to be over written always panic as
800	  the content of the corrupted region can no longer be trusted.
801	  This is to ensure no erroneous behaviour occurs which could result in
802	  data corruption or a sporadic crash at a later stage once the region
803	  is examined. The runtime overhead introduced is minimal.
804
805config ARCH_HAS_DEBUG_VM_PGTABLE
806	bool
807	help
808	  An architecture should select this when it can successfully
809	  build and run DEBUG_VM_PGTABLE.
810
811config DEBUG_VM_IRQSOFF
812	def_bool DEBUG_VM && !PREEMPT_RT
813
814config DEBUG_VM
815	bool "Debug VM"
816	depends on DEBUG_KERNEL
817	help
818	  Enable this to turn on extended checks in the virtual-memory system
819	  that may impact performance.
820
821	  If unsure, say N.
822
823config DEBUG_VM_SHOOT_LAZIES
824	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
825	depends on DEBUG_VM
826	depends on MMU_LAZY_TLB_SHOOTDOWN
827	help
828	  Enable additional IPIs that ensure lazy tlb mm references are removed
829	  before the mm is freed.
830
831	  If unsure, say N.
832
833config DEBUG_VM_MAPLE_TREE
834	bool "Debug VM maple trees"
835	depends on DEBUG_VM
836	select DEBUG_MAPLE_TREE
837	help
838	  Enable VM maple tree debugging information and extra validations.
839
840	  If unsure, say N.
841
842config DEBUG_VM_RB
843	bool "Debug VM red-black trees"
844	depends on DEBUG_VM
845	help
846	  Enable VM red-black tree debugging information and extra validations.
847
848	  If unsure, say N.
849
850config DEBUG_VM_PGFLAGS
851	bool "Debug page-flags operations"
852	depends on DEBUG_VM
853	help
854	  Enables extra validation on page flags operations.
855
856	  If unsure, say N.
857
858config DEBUG_VM_PGTABLE
859	bool "Debug arch page table for semantics compliance"
860	depends on MMU
861	depends on ARCH_HAS_DEBUG_VM_PGTABLE
862	default y if DEBUG_VM
863	help
864	  This option provides a debug method which can be used to test
865	  architecture page table helper functions on various platforms in
866	  verifying if they comply with expected generic MM semantics. This
867	  will help architecture code in making sure that any changes or
868	  new additions of these helpers still conform to expected
869	  semantics of the generic MM. Platforms will have to opt in for
870	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
871
872	  If unsure, say N.
873
874config ARCH_HAS_DEBUG_VIRTUAL
875	bool
876
877config DEBUG_VIRTUAL
878	bool "Debug VM translations"
879	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
880	help
881	  Enable some costly sanity checks in virtual to page code. This can
882	  catch mistakes with virt_to_page() and friends.
883
884	  If unsure, say N.
885
886config DEBUG_NOMMU_REGIONS
887	bool "Debug the global anon/private NOMMU mapping region tree"
888	depends on DEBUG_KERNEL && !MMU
889	help
890	  This option causes the global tree of anonymous and private mapping
891	  regions to be regularly checked for invalid topology.
892
893config DEBUG_MEMORY_INIT
894	bool "Debug memory initialisation" if EXPERT
895	default !EXPERT
896	help
897	  Enable this for additional checks during memory initialisation.
898	  The sanity checks verify aspects of the VM such as the memory model
899	  and other information provided by the architecture. Verbose
900	  information will be printed at KERN_DEBUG loglevel depending
901	  on the mminit_loglevel= command-line option.
902
903	  If unsure, say Y
904
905config MEMORY_NOTIFIER_ERROR_INJECT
906	tristate "Memory hotplug notifier error injection module"
907	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
908	help
909	  This option provides the ability to inject artificial errors to
910	  memory hotplug notifier chain callbacks.  It is controlled through
911	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
912
913	  If the notifier call chain should be failed with some events
914	  notified, write the error code to "actions/<notifier event>/error".
915
916	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
917
918	  # cd /sys/kernel/debug/notifier-error-inject/memory
919	  # echo -12 > actions/MEM_GOING_OFFLINE/error
920	  # echo offline > /sys/devices/system/memory/memoryXXX/state
921	  bash: echo: write error: Cannot allocate memory
922
923	  To compile this code as a module, choose M here: the module will
924	  be called memory-notifier-error-inject.
925
926	  If unsure, say N.
927
928config DEBUG_PER_CPU_MAPS
929	bool "Debug access to per_cpu maps"
930	depends on DEBUG_KERNEL
931	depends on SMP
932	help
933	  Say Y to verify that the per_cpu map being accessed has
934	  been set up. This adds a fair amount of code to kernel memory
935	  and decreases performance.
936
937	  Say N if unsure.
938
939config DEBUG_KMAP_LOCAL
940	bool "Debug kmap_local temporary mappings"
941	depends on DEBUG_KERNEL && KMAP_LOCAL
942	help
943	  This option enables additional error checking for the kmap_local
944	  infrastructure.  Disable for production use.
945
946config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
947	bool
948
949config DEBUG_KMAP_LOCAL_FORCE_MAP
950	bool "Enforce kmap_local temporary mappings"
951	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
952	select KMAP_LOCAL
953	select DEBUG_KMAP_LOCAL
954	help
955	  This option enforces temporary mappings through the kmap_local
956	  mechanism for non-highmem pages and on non-highmem systems.
957	  Disable this for production systems!
958
959config DEBUG_HIGHMEM
960	bool "Highmem debugging"
961	depends on DEBUG_KERNEL && HIGHMEM
962	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
963	select DEBUG_KMAP_LOCAL
964	help
965	  This option enables additional error checking for high memory
966	  systems.  Disable for production systems.
967
968config HAVE_DEBUG_STACKOVERFLOW
969	bool
970
971config DEBUG_STACKOVERFLOW
972	bool "Check for stack overflows"
973	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
974	help
975	  Say Y here if you want to check for overflows of kernel, IRQ
976	  and exception stacks (if your architecture uses them). This
977	  option will show detailed messages if free stack space drops
978	  below a certain limit.
979
980	  These kinds of bugs usually occur when call-chains in the
981	  kernel get too deep, especially when interrupts are
982	  involved.
983
984	  Use this in cases where you see apparently random memory
985	  corruption, especially if it appears in 'struct thread_info'
986
987	  If in doubt, say "N".
988
989config CODE_TAGGING
990	bool
991	select KALLSYMS
992
993config MEM_ALLOC_PROFILING
994	bool "Enable memory allocation profiling"
995	default n
996	depends on PROC_FS
997	depends on !DEBUG_FORCE_WEAK_PER_CPU
998	select CODE_TAGGING
999	select PAGE_EXTENSION
1000	select SLAB_OBJ_EXT
1001	help
1002	  Track allocation source code and record total allocation size
1003	  initiated at that code location. The mechanism can be used to track
1004	  memory leaks with a low performance and memory impact.
1005
1006config MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1007	bool "Enable memory allocation profiling by default"
1008	default y
1009	depends on MEM_ALLOC_PROFILING
1010
1011config MEM_ALLOC_PROFILING_DEBUG
1012	bool "Memory allocation profiler debugging"
1013	default n
1014	depends on MEM_ALLOC_PROFILING
1015	select MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
1016	help
1017	  Adds warnings with helpful error messages for memory allocation
1018	  profiling.
1019
1020source "lib/Kconfig.kasan"
1021source "lib/Kconfig.kfence"
1022source "lib/Kconfig.kmsan"
1023
1024endmenu # "Memory Debugging"
1025
1026config DEBUG_SHIRQ
1027	bool "Debug shared IRQ handlers"
1028	depends on DEBUG_KERNEL
1029	help
1030	  Enable this to generate a spurious interrupt just before a shared
1031	  interrupt handler is deregistered (generating one when registering
1032	  is currently disabled). Drivers need to handle this correctly. Some
1033	  don't and need to be caught.
1034
1035menu "Debug Oops, Lockups and Hangs"
1036
1037config PANIC_ON_OOPS
1038	bool "Panic on Oops"
1039	help
1040	  Say Y here to enable the kernel to panic when it oopses. This
1041	  has the same effect as setting oops=panic on the kernel command
1042	  line.
1043
1044	  This feature is useful to ensure that the kernel does not do
1045	  anything erroneous after an oops which could result in data
1046	  corruption or other issues.
1047
1048	  Say N if unsure.
1049
1050config PANIC_ON_OOPS_VALUE
1051	int
1052	range 0 1
1053	default 0 if !PANIC_ON_OOPS
1054	default 1 if PANIC_ON_OOPS
1055
1056config PANIC_TIMEOUT
1057	int "panic timeout"
1058	default 0
1059	help
1060	  Set the timeout value (in seconds) until a reboot occurs when
1061	  the kernel panics. If n = 0, then we wait forever. A timeout
1062	  value n > 0 will wait n seconds before rebooting, while a timeout
1063	  value n < 0 will reboot immediately. This setting can be overridden
1064	  with the kernel command line option panic=, and from userspace via
1065	  /proc/sys/kernel/panic.
1066
1067config LOCKUP_DETECTOR
1068	bool
1069
1070config SOFTLOCKUP_DETECTOR
1071	bool "Detect Soft Lockups"
1072	depends on DEBUG_KERNEL && !S390
1073	select LOCKUP_DETECTOR
1074	help
1075	  Say Y here to enable the kernel to act as a watchdog to detect
1076	  soft lockups.
1077
1078	  Softlockups are bugs that cause the kernel to loop in kernel
1079	  mode for more than 20 seconds, without giving other tasks a
1080	  chance to run.  The current stack trace is displayed upon
1081	  detection and the system will stay locked up.
1082
1083config SOFTLOCKUP_DETECTOR_INTR_STORM
1084	bool "Detect Interrupt Storm in Soft Lockups"
1085	depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING
1086	select GENERIC_IRQ_STAT_SNAPSHOT
1087	default y if NR_CPUS <= 128
1088	help
1089	  Say Y here to enable the kernel to detect interrupt storm
1090	  during "soft lockups".
1091
1092	  "soft lockups" can be caused by a variety of reasons. If one is
1093	  caused by an interrupt storm, then the storming interrupts will not
1094	  be on the callstack. To detect this case, it is necessary to report
1095	  the CPU stats and the interrupt counts during the "soft lockups".
1096
1097config BOOTPARAM_SOFTLOCKUP_PANIC
1098	bool "Panic (Reboot) On Soft Lockups"
1099	depends on SOFTLOCKUP_DETECTOR
1100	help
1101	  Say Y here to enable the kernel to panic on "soft lockups",
1102	  which are bugs that cause the kernel to loop in kernel
1103	  mode for more than 20 seconds (configurable using the watchdog_thresh
1104	  sysctl), without giving other tasks a chance to run.
1105
1106	  The panic can be used in combination with panic_timeout,
1107	  to cause the system to reboot automatically after a
1108	  lockup has been detected. This feature is useful for
1109	  high-availability systems that have uptime guarantees and
1110	  where a lockup must be resolved ASAP.
1111
1112	  Say N if unsure.
1113
1114config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1115	bool
1116	depends on SMP
1117	default y
1118
1119#
1120# Global switch whether to build a hardlockup detector at all. It is available
1121# only when the architecture supports at least one implementation. There are
1122# two exceptions. The hardlockup detector is never enabled on:
1123#
1124#	s390: it reported many false positives there
1125#
1126#	sparc64: has a custom implementation which is not using the common
1127#		hardlockup command line options and sysctl interface.
1128#
1129config HARDLOCKUP_DETECTOR
1130	bool "Detect Hard Lockups"
1131	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1132	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1133	imply HARDLOCKUP_DETECTOR_PERF
1134	imply HARDLOCKUP_DETECTOR_BUDDY
1135	imply HARDLOCKUP_DETECTOR_ARCH
1136	select LOCKUP_DETECTOR
1137
1138	help
1139	  Say Y here to enable the kernel to act as a watchdog to detect
1140	  hard lockups.
1141
1142	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1143	  for more than 10 seconds, without letting other interrupts have a
1144	  chance to run.  The current stack trace is displayed upon detection
1145	  and the system will stay locked up.
1146
1147#
1148# Note that arch-specific variants are always preferred.
1149#
1150config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1151	bool "Prefer the buddy CPU hardlockup detector"
1152	depends on HARDLOCKUP_DETECTOR
1153	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1154	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1155	help
1156	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1157
1158	  With the buddy detector, each CPU uses its softlockup hrtimer
1159	  to check that the next CPU is processing hrtimer interrupts by
1160	  verifying that a counter is increasing.
1161
1162	  This hardlockup detector is useful on systems that don't have
1163	  an arch-specific hardlockup detector or if resources needed
1164	  for the hardlockup detector are better used for other things.
1165
1166config HARDLOCKUP_DETECTOR_PERF
1167	bool
1168	depends on HARDLOCKUP_DETECTOR
1169	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1170	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1171	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1172
1173config HARDLOCKUP_DETECTOR_BUDDY
1174	bool
1175	depends on HARDLOCKUP_DETECTOR
1176	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1177	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1178	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1179	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1180
1181config HARDLOCKUP_DETECTOR_ARCH
1182	bool
1183	depends on HARDLOCKUP_DETECTOR
1184	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1185	help
1186	  The arch-specific implementation of the hardlockup detector will
1187	  be used.
1188
1189#
1190# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1191# interrupts. This config enables functions managing this common code.
1192#
1193config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1194	bool
1195	select SOFTLOCKUP_DETECTOR
1196
1197#
1198# Enables a timestamp based low pass filter to compensate for perf based
1199# hard lockup detection which runs too fast due to turbo modes.
1200#
1201config HARDLOCKUP_CHECK_TIMESTAMP
1202	bool
1203
1204config BOOTPARAM_HARDLOCKUP_PANIC
1205	bool "Panic (Reboot) On Hard Lockups"
1206	depends on HARDLOCKUP_DETECTOR
1207	help
1208	  Say Y here to enable the kernel to panic on "hard lockups",
1209	  which are bugs that cause the kernel to loop in kernel
1210	  mode with interrupts disabled for more than 10 seconds (configurable
1211	  using the watchdog_thresh sysctl).
1212
1213	  Say N if unsure.
1214
1215config DETECT_HUNG_TASK
1216	bool "Detect Hung Tasks"
1217	depends on DEBUG_KERNEL
1218	default SOFTLOCKUP_DETECTOR
1219	help
1220	  Say Y here to enable the kernel to detect "hung tasks",
1221	  which are bugs that cause the task to be stuck in
1222	  uninterruptible "D" state indefinitely.
1223
1224	  When a hung task is detected, the kernel will print the
1225	  current stack trace (which you should report), but the
1226	  task will stay in uninterruptible state. If lockdep is
1227	  enabled then all held locks will also be reported. This
1228	  feature has negligible overhead.
1229
1230config DEFAULT_HUNG_TASK_TIMEOUT
1231	int "Default timeout for hung task detection (in seconds)"
1232	depends on DETECT_HUNG_TASK
1233	default 120
1234	help
1235	  This option controls the default timeout (in seconds) used
1236	  to determine when a task has become non-responsive and should
1237	  be considered hung.
1238
1239	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1240	  sysctl or by writing a value to
1241	  /proc/sys/kernel/hung_task_timeout_secs.
1242
1243	  A timeout of 0 disables the check.  The default is two minutes.
1244	  Keeping the default should be fine in most cases.
1245
1246config BOOTPARAM_HUNG_TASK_PANIC
1247	bool "Panic (Reboot) On Hung Tasks"
1248	depends on DETECT_HUNG_TASK
1249	help
1250	  Say Y here to enable the kernel to panic on "hung tasks",
1251	  which are bugs that cause the kernel to leave a task stuck
1252	  in uninterruptible "D" state.
1253
1254	  The panic can be used in combination with panic_timeout,
1255	  to cause the system to reboot automatically after a
1256	  hung task has been detected. This feature is useful for
1257	  high-availability systems that have uptime guarantees and
1258	  where a hung tasks must be resolved ASAP.
1259
1260	  Say N if unsure.
1261
1262config WQ_WATCHDOG
1263	bool "Detect Workqueue Stalls"
1264	depends on DEBUG_KERNEL
1265	help
1266	  Say Y here to enable stall detection on workqueues.  If a
1267	  worker pool doesn't make forward progress on a pending work
1268	  item for over a given amount of time, 30s by default, a
1269	  warning message is printed along with dump of workqueue
1270	  state.  This can be configured through kernel parameter
1271	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1272
1273config WQ_CPU_INTENSIVE_REPORT
1274	bool "Report per-cpu work items which hog CPU for too long"
1275	depends on DEBUG_KERNEL
1276	help
1277	  Say Y here to enable reporting of concurrency-managed per-cpu work
1278	  items that hog CPUs for longer than
1279	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1280	  detects and excludes them from concurrency management to prevent
1281	  them from stalling other per-cpu work items. Occassional
1282	  triggering may not necessarily indicate a problem. Repeated
1283	  triggering likely indicates that the work item should be switched
1284	  to use an unbound workqueue.
1285
1286config TEST_LOCKUP
1287	tristate "Test module to generate lockups"
1288	depends on m
1289	help
1290	  This builds the "test_lockup" module that helps to make sure
1291	  that watchdogs and lockup detectors are working properly.
1292
1293	  Depending on module parameters it could emulate soft or hard
1294	  lockup, "hung task", or locking arbitrary lock for a long time.
1295	  Also it could generate series of lockups with cooling-down periods.
1296
1297	  If unsure, say N.
1298
1299endmenu # "Debug lockups and hangs"
1300
1301menu "Scheduler Debugging"
1302
1303config SCHED_DEBUG
1304	bool "Collect scheduler debugging info"
1305	depends on DEBUG_KERNEL && DEBUG_FS
1306	default y
1307	help
1308	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1309	  that can help debug the scheduler. The runtime overhead of this
1310	  option is minimal.
1311
1312config SCHED_INFO
1313	bool
1314	default n
1315
1316config SCHEDSTATS
1317	bool "Collect scheduler statistics"
1318	depends on PROC_FS
1319	select SCHED_INFO
1320	help
1321	  If you say Y here, additional code will be inserted into the
1322	  scheduler and related routines to collect statistics about
1323	  scheduler behavior and provide them in /proc/schedstat.  These
1324	  stats may be useful for both tuning and debugging the scheduler
1325	  If you aren't debugging the scheduler or trying to tune a specific
1326	  application, you can say N to avoid the very slight overhead
1327	  this adds.
1328
1329endmenu
1330
1331config DEBUG_TIMEKEEPING
1332	bool "Enable extra timekeeping sanity checking"
1333	help
1334	  This option will enable additional timekeeping sanity checks
1335	  which may be helpful when diagnosing issues where timekeeping
1336	  problems are suspected.
1337
1338	  This may include checks in the timekeeping hotpaths, so this
1339	  option may have a (very small) performance impact to some
1340	  workloads.
1341
1342	  If unsure, say N.
1343
1344config DEBUG_PREEMPT
1345	bool "Debug preemptible kernel"
1346	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1347	help
1348	  If you say Y here then the kernel will use a debug variant of the
1349	  commonly used smp_processor_id() function and will print warnings
1350	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1351	  will detect preemption count underflows.
1352
1353	  This option has potential to introduce high runtime overhead,
1354	  depending on workload as it triggers debugging routines for each
1355	  this_cpu operation. It should only be used for debugging purposes.
1356
1357menu "Lock Debugging (spinlocks, mutexes, etc...)"
1358
1359config LOCK_DEBUGGING_SUPPORT
1360	bool
1361	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1362	default y
1363
1364config PROVE_LOCKING
1365	bool "Lock debugging: prove locking correctness"
1366	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1367	select LOCKDEP
1368	select DEBUG_SPINLOCK
1369	select DEBUG_MUTEXES if !PREEMPT_RT
1370	select DEBUG_RT_MUTEXES if RT_MUTEXES
1371	select DEBUG_RWSEMS if !PREEMPT_RT
1372	select DEBUG_WW_MUTEX_SLOWPATH
1373	select DEBUG_LOCK_ALLOC
1374	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1375	select TRACE_IRQFLAGS
1376	default n
1377	help
1378	 This feature enables the kernel to prove that all locking
1379	 that occurs in the kernel runtime is mathematically
1380	 correct: that under no circumstance could an arbitrary (and
1381	 not yet triggered) combination of observed locking
1382	 sequences (on an arbitrary number of CPUs, running an
1383	 arbitrary number of tasks and interrupt contexts) cause a
1384	 deadlock.
1385
1386	 In short, this feature enables the kernel to report locking
1387	 related deadlocks before they actually occur.
1388
1389	 The proof does not depend on how hard and complex a
1390	 deadlock scenario would be to trigger: how many
1391	 participant CPUs, tasks and irq-contexts would be needed
1392	 for it to trigger. The proof also does not depend on
1393	 timing: if a race and a resulting deadlock is possible
1394	 theoretically (no matter how unlikely the race scenario
1395	 is), it will be proven so and will immediately be
1396	 reported by the kernel (once the event is observed that
1397	 makes the deadlock theoretically possible).
1398
1399	 If a deadlock is impossible (i.e. the locking rules, as
1400	 observed by the kernel, are mathematically correct), the
1401	 kernel reports nothing.
1402
1403	 NOTE: this feature can also be enabled for rwlocks, mutexes
1404	 and rwsems - in which case all dependencies between these
1405	 different locking variants are observed and mapped too, and
1406	 the proof of observed correctness is also maintained for an
1407	 arbitrary combination of these separate locking variants.
1408
1409	 For more details, see Documentation/locking/lockdep-design.rst.
1410
1411config PROVE_RAW_LOCK_NESTING
1412	bool
1413	depends on PROVE_LOCKING
1414	default y
1415	help
1416	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1417	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1418	 not violated.
1419
1420config LOCK_STAT
1421	bool "Lock usage statistics"
1422	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1423	select LOCKDEP
1424	select DEBUG_SPINLOCK
1425	select DEBUG_MUTEXES if !PREEMPT_RT
1426	select DEBUG_RT_MUTEXES if RT_MUTEXES
1427	select DEBUG_LOCK_ALLOC
1428	default n
1429	help
1430	 This feature enables tracking lock contention points
1431
1432	 For more details, see Documentation/locking/lockstat.rst
1433
1434	 This also enables lock events required by "perf lock",
1435	 subcommand of perf.
1436	 If you want to use "perf lock", you also need to turn on
1437	 CONFIG_EVENT_TRACING.
1438
1439	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1440	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1441
1442config DEBUG_RT_MUTEXES
1443	bool "RT Mutex debugging, deadlock detection"
1444	depends on DEBUG_KERNEL && RT_MUTEXES
1445	help
1446	 This allows rt mutex semantics violations and rt mutex related
1447	 deadlocks (lockups) to be detected and reported automatically.
1448
1449config DEBUG_SPINLOCK
1450	bool "Spinlock and rw-lock debugging: basic checks"
1451	depends on DEBUG_KERNEL
1452	select UNINLINE_SPIN_UNLOCK
1453	help
1454	  Say Y here and build SMP to catch missing spinlock initialization
1455	  and certain other kinds of spinlock errors commonly made.  This is
1456	  best used in conjunction with the NMI watchdog so that spinlock
1457	  deadlocks are also debuggable.
1458
1459config DEBUG_MUTEXES
1460	bool "Mutex debugging: basic checks"
1461	depends on DEBUG_KERNEL && !PREEMPT_RT
1462	help
1463	 This feature allows mutex semantics violations to be detected and
1464	 reported.
1465
1466config DEBUG_WW_MUTEX_SLOWPATH
1467	bool "Wait/wound mutex debugging: Slowpath testing"
1468	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1469	select DEBUG_LOCK_ALLOC
1470	select DEBUG_SPINLOCK
1471	select DEBUG_MUTEXES if !PREEMPT_RT
1472	select DEBUG_RT_MUTEXES if PREEMPT_RT
1473	help
1474	 This feature enables slowpath testing for w/w mutex users by
1475	 injecting additional -EDEADLK wound/backoff cases. Together with
1476	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1477	 will test all possible w/w mutex interface abuse with the
1478	 exception of simply not acquiring all the required locks.
1479	 Note that this feature can introduce significant overhead, so
1480	 it really should not be enabled in a production or distro kernel,
1481	 even a debug kernel.  If you are a driver writer, enable it.  If
1482	 you are a distro, do not.
1483
1484config DEBUG_RWSEMS
1485	bool "RW Semaphore debugging: basic checks"
1486	depends on DEBUG_KERNEL && !PREEMPT_RT
1487	help
1488	  This debugging feature allows mismatched rw semaphore locks
1489	  and unlocks to be detected and reported.
1490
1491config DEBUG_LOCK_ALLOC
1492	bool "Lock debugging: detect incorrect freeing of live locks"
1493	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1494	select DEBUG_SPINLOCK
1495	select DEBUG_MUTEXES if !PREEMPT_RT
1496	select DEBUG_RT_MUTEXES if RT_MUTEXES
1497	select LOCKDEP
1498	help
1499	 This feature will check whether any held lock (spinlock, rwlock,
1500	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1501	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1502	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1503	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1504	 held during task exit.
1505
1506config LOCKDEP
1507	bool
1508	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1509	select STACKTRACE
1510	select KALLSYMS
1511	select KALLSYMS_ALL
1512
1513config LOCKDEP_SMALL
1514	bool
1515
1516config LOCKDEP_BITS
1517	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1518	depends on LOCKDEP && !LOCKDEP_SMALL
1519	range 10 30
1520	default 15
1521	help
1522	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1523
1524config LOCKDEP_CHAINS_BITS
1525	int "Bitsize for MAX_LOCKDEP_CHAINS"
1526	depends on LOCKDEP && !LOCKDEP_SMALL
1527	range 10 21
1528	default 16
1529	help
1530	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1531
1532config LOCKDEP_STACK_TRACE_BITS
1533	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1534	depends on LOCKDEP && !LOCKDEP_SMALL
1535	range 10 30
1536	default 19
1537	help
1538	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1539
1540config LOCKDEP_STACK_TRACE_HASH_BITS
1541	int "Bitsize for STACK_TRACE_HASH_SIZE"
1542	depends on LOCKDEP && !LOCKDEP_SMALL
1543	range 10 30
1544	default 14
1545	help
1546	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1547
1548config LOCKDEP_CIRCULAR_QUEUE_BITS
1549	int "Bitsize for elements in circular_queue struct"
1550	depends on LOCKDEP
1551	range 10 30
1552	default 12
1553	help
1554	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1555
1556config DEBUG_LOCKDEP
1557	bool "Lock dependency engine debugging"
1558	depends on DEBUG_KERNEL && LOCKDEP
1559	select DEBUG_IRQFLAGS
1560	help
1561	  If you say Y here, the lock dependency engine will do
1562	  additional runtime checks to debug itself, at the price
1563	  of more runtime overhead.
1564
1565config DEBUG_ATOMIC_SLEEP
1566	bool "Sleep inside atomic section checking"
1567	select PREEMPT_COUNT
1568	depends on DEBUG_KERNEL
1569	depends on !ARCH_NO_PREEMPT
1570	help
1571	  If you say Y here, various routines which may sleep will become very
1572	  noisy if they are called inside atomic sections: when a spinlock is
1573	  held, inside an rcu read side critical section, inside preempt disabled
1574	  sections, inside an interrupt, etc...
1575
1576config DEBUG_LOCKING_API_SELFTESTS
1577	bool "Locking API boot-time self-tests"
1578	depends on DEBUG_KERNEL
1579	help
1580	  Say Y here if you want the kernel to run a short self-test during
1581	  bootup. The self-test checks whether common types of locking bugs
1582	  are detected by debugging mechanisms or not. (if you disable
1583	  lock debugging then those bugs won't be detected of course.)
1584	  The following locking APIs are covered: spinlocks, rwlocks,
1585	  mutexes and rwsems.
1586
1587config LOCK_TORTURE_TEST
1588	tristate "torture tests for locking"
1589	depends on DEBUG_KERNEL
1590	select TORTURE_TEST
1591	help
1592	  This option provides a kernel module that runs torture tests
1593	  on kernel locking primitives.  The kernel module may be built
1594	  after the fact on the running kernel to be tested, if desired.
1595
1596	  Say Y here if you want kernel locking-primitive torture tests
1597	  to be built into the kernel.
1598	  Say M if you want these torture tests to build as a module.
1599	  Say N if you are unsure.
1600
1601config WW_MUTEX_SELFTEST
1602	tristate "Wait/wound mutex selftests"
1603	help
1604	  This option provides a kernel module that runs tests on the
1605	  on the struct ww_mutex locking API.
1606
1607	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1608	  with this test harness.
1609
1610	  Say M if you want these self tests to build as a module.
1611	  Say N if you are unsure.
1612
1613config SCF_TORTURE_TEST
1614	tristate "torture tests for smp_call_function*()"
1615	depends on DEBUG_KERNEL
1616	select TORTURE_TEST
1617	help
1618	  This option provides a kernel module that runs torture tests
1619	  on the smp_call_function() family of primitives.  The kernel
1620	  module may be built after the fact on the running kernel to
1621	  be tested, if desired.
1622
1623config CSD_LOCK_WAIT_DEBUG
1624	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1625	depends on DEBUG_KERNEL
1626	depends on SMP
1627	depends on 64BIT
1628	default n
1629	help
1630	  This option enables debug prints when CPUs are slow to respond
1631	  to the smp_call_function*() IPI wrappers.  These debug prints
1632	  include the IPI handler function currently executing (if any)
1633	  and relevant stack traces.
1634
1635config CSD_LOCK_WAIT_DEBUG_DEFAULT
1636	bool "Default csd_lock_wait() debugging on at boot time"
1637	depends on CSD_LOCK_WAIT_DEBUG
1638	depends on 64BIT
1639	default n
1640	help
1641	  This option causes the csdlock_debug= kernel boot parameter to
1642	  default to 1 (basic debugging) instead of 0 (no debugging).
1643
1644endmenu # lock debugging
1645
1646config TRACE_IRQFLAGS
1647	depends on TRACE_IRQFLAGS_SUPPORT
1648	bool
1649	help
1650	  Enables hooks to interrupt enabling and disabling for
1651	  either tracing or lock debugging.
1652
1653config TRACE_IRQFLAGS_NMI
1654	def_bool y
1655	depends on TRACE_IRQFLAGS
1656	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1657
1658config NMI_CHECK_CPU
1659	bool "Debugging for CPUs failing to respond to backtrace requests"
1660	depends on DEBUG_KERNEL
1661	depends on X86
1662	default n
1663	help
1664	  Enables debug prints when a CPU fails to respond to a given
1665	  backtrace NMI.  These prints provide some reasons why a CPU
1666	  might legitimately be failing to respond, for example, if it
1667	  is offline of if ignore_nmis is set.
1668
1669config DEBUG_IRQFLAGS
1670	bool "Debug IRQ flag manipulation"
1671	help
1672	  Enables checks for potentially unsafe enabling or disabling of
1673	  interrupts, such as calling raw_local_irq_restore() when interrupts
1674	  are enabled.
1675
1676config STACKTRACE
1677	bool "Stack backtrace support"
1678	depends on STACKTRACE_SUPPORT
1679	help
1680	  This option causes the kernel to create a /proc/pid/stack for
1681	  every process, showing its current stack trace.
1682	  It is also used by various kernel debugging features that require
1683	  stack trace generation.
1684
1685config WARN_ALL_UNSEEDED_RANDOM
1686	bool "Warn for all uses of unseeded randomness"
1687	default n
1688	help
1689	  Some parts of the kernel contain bugs relating to their use of
1690	  cryptographically secure random numbers before it's actually possible
1691	  to generate those numbers securely. This setting ensures that these
1692	  flaws don't go unnoticed, by enabling a message, should this ever
1693	  occur. This will allow people with obscure setups to know when things
1694	  are going wrong, so that they might contact developers about fixing
1695	  it.
1696
1697	  Unfortunately, on some models of some architectures getting
1698	  a fully seeded CRNG is extremely difficult, and so this can
1699	  result in dmesg getting spammed for a surprisingly long
1700	  time.  This is really bad from a security perspective, and
1701	  so architecture maintainers really need to do what they can
1702	  to get the CRNG seeded sooner after the system is booted.
1703	  However, since users cannot do anything actionable to
1704	  address this, by default this option is disabled.
1705
1706	  Say Y here if you want to receive warnings for all uses of
1707	  unseeded randomness.  This will be of use primarily for
1708	  those developers interested in improving the security of
1709	  Linux kernels running on their architecture (or
1710	  subarchitecture).
1711
1712config DEBUG_KOBJECT
1713	bool "kobject debugging"
1714	depends on DEBUG_KERNEL
1715	help
1716	  If you say Y here, some extra kobject debugging messages will be sent
1717	  to the syslog.
1718
1719config DEBUG_KOBJECT_RELEASE
1720	bool "kobject release debugging"
1721	depends on DEBUG_OBJECTS_TIMERS
1722	help
1723	  kobjects are reference counted objects.  This means that their
1724	  last reference count put is not predictable, and the kobject can
1725	  live on past the point at which a driver decides to drop its
1726	  initial reference to the kobject gained on allocation.  An
1727	  example of this would be a struct device which has just been
1728	  unregistered.
1729
1730	  However, some buggy drivers assume that after such an operation,
1731	  the memory backing the kobject can be immediately freed.  This
1732	  goes completely against the principles of a refcounted object.
1733
1734	  If you say Y here, the kernel will delay the release of kobjects
1735	  on the last reference count to improve the visibility of this
1736	  kind of kobject release bug.
1737
1738config HAVE_DEBUG_BUGVERBOSE
1739	bool
1740
1741menu "Debug kernel data structures"
1742
1743config DEBUG_LIST
1744	bool "Debug linked list manipulation"
1745	depends on DEBUG_KERNEL
1746	select LIST_HARDENED
1747	help
1748	  Enable this to turn on extended checks in the linked-list walking
1749	  routines.
1750
1751	  This option trades better quality error reports for performance, and
1752	  is more suitable for kernel debugging. If you care about performance,
1753	  you should only enable CONFIG_LIST_HARDENED instead.
1754
1755	  If unsure, say N.
1756
1757config DEBUG_PLIST
1758	bool "Debug priority linked list manipulation"
1759	depends on DEBUG_KERNEL
1760	help
1761	  Enable this to turn on extended checks in the priority-ordered
1762	  linked-list (plist) walking routines.  This checks the entire
1763	  list multiple times during each manipulation.
1764
1765	  If unsure, say N.
1766
1767config DEBUG_SG
1768	bool "Debug SG table operations"
1769	depends on DEBUG_KERNEL
1770	help
1771	  Enable this to turn on checks on scatter-gather tables. This can
1772	  help find problems with drivers that do not properly initialize
1773	  their sg tables.
1774
1775	  If unsure, say N.
1776
1777config DEBUG_NOTIFIERS
1778	bool "Debug notifier call chains"
1779	depends on DEBUG_KERNEL
1780	help
1781	  Enable this to turn on sanity checking for notifier call chains.
1782	  This is most useful for kernel developers to make sure that
1783	  modules properly unregister themselves from notifier chains.
1784	  This is a relatively cheap check but if you care about maximum
1785	  performance, say N.
1786
1787config DEBUG_CLOSURES
1788	bool "Debug closures (bcache async widgits)"
1789	depends on CLOSURES
1790	select DEBUG_FS
1791	help
1792	  Keeps all active closures in a linked list and provides a debugfs
1793	  interface to list them, which makes it possible to see asynchronous
1794	  operations that get stuck.
1795
1796config DEBUG_MAPLE_TREE
1797	bool "Debug maple trees"
1798	depends on DEBUG_KERNEL
1799	help
1800	  Enable maple tree debugging information and extra validations.
1801
1802	  If unsure, say N.
1803
1804endmenu
1805
1806source "kernel/rcu/Kconfig.debug"
1807
1808config DEBUG_WQ_FORCE_RR_CPU
1809	bool "Force round-robin CPU selection for unbound work items"
1810	depends on DEBUG_KERNEL
1811	default n
1812	help
1813	  Workqueue used to implicitly guarantee that work items queued
1814	  without explicit CPU specified are put on the local CPU.  This
1815	  guarantee is no longer true and while local CPU is still
1816	  preferred work items may be put on foreign CPUs.  Kernel
1817	  parameter "workqueue.debug_force_rr_cpu" is added to force
1818	  round-robin CPU selection to flush out usages which depend on the
1819	  now broken guarantee.  This config option enables the debug
1820	  feature by default.  When enabled, memory and cache locality will
1821	  be impacted.
1822
1823config CPU_HOTPLUG_STATE_CONTROL
1824	bool "Enable CPU hotplug state control"
1825	depends on DEBUG_KERNEL
1826	depends on HOTPLUG_CPU
1827	default n
1828	help
1829	  Allows to write steps between "offline" and "online" to the CPUs
1830	  sysfs target file so states can be stepped granular. This is a debug
1831	  option for now as the hotplug machinery cannot be stopped and
1832	  restarted at arbitrary points yet.
1833
1834	  Say N if your are unsure.
1835
1836config LATENCYTOP
1837	bool "Latency measuring infrastructure"
1838	depends on DEBUG_KERNEL
1839	depends on STACKTRACE_SUPPORT
1840	depends on PROC_FS
1841	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1842	select KALLSYMS
1843	select KALLSYMS_ALL
1844	select STACKTRACE
1845	select SCHEDSTATS
1846	help
1847	  Enable this option if you want to use the LatencyTOP tool
1848	  to find out which userspace is blocking on what kernel operations.
1849
1850config DEBUG_CGROUP_REF
1851	bool "Disable inlining of cgroup css reference count functions"
1852	depends on DEBUG_KERNEL
1853	depends on CGROUPS
1854	depends on KPROBES
1855	default n
1856	help
1857	  Force cgroup css reference count functions to not be inlined so
1858	  that they can be kprobed for debugging.
1859
1860source "kernel/trace/Kconfig"
1861
1862config PROVIDE_OHCI1394_DMA_INIT
1863	bool "Remote debugging over FireWire early on boot"
1864	depends on PCI && X86
1865	help
1866	  If you want to debug problems which hang or crash the kernel early
1867	  on boot and the crashing machine has a FireWire port, you can use
1868	  this feature to remotely access the memory of the crashed machine
1869	  over FireWire. This employs remote DMA as part of the OHCI1394
1870	  specification which is now the standard for FireWire controllers.
1871
1872	  With remote DMA, you can monitor the printk buffer remotely using
1873	  firescope and access all memory below 4GB using fireproxy from gdb.
1874	  Even controlling a kernel debugger is possible using remote DMA.
1875
1876	  Usage:
1877
1878	  If ohci1394_dma=early is used as boot parameter, it will initialize
1879	  all OHCI1394 controllers which are found in the PCI config space.
1880
1881	  As all changes to the FireWire bus such as enabling and disabling
1882	  devices cause a bus reset and thereby disable remote DMA for all
1883	  devices, be sure to have the cable plugged and FireWire enabled on
1884	  the debugging host before booting the debug target for debugging.
1885
1886	  This code (~1k) is freed after boot. By then, the firewire stack
1887	  in charge of the OHCI-1394 controllers should be used instead.
1888
1889	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1890
1891source "samples/Kconfig"
1892
1893config ARCH_HAS_DEVMEM_IS_ALLOWED
1894	bool
1895
1896config STRICT_DEVMEM
1897	bool "Filter access to /dev/mem"
1898	depends on MMU && DEVMEM
1899	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1900	default y if PPC || X86 || ARM64
1901	help
1902	  If this option is disabled, you allow userspace (root) access to all
1903	  of memory, including kernel and userspace memory. Accidental
1904	  access to this is obviously disastrous, but specific access can
1905	  be used by people debugging the kernel. Note that with PAT support
1906	  enabled, even in this case there are restrictions on /dev/mem
1907	  use due to the cache aliasing requirements.
1908
1909	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1910	  file only allows userspace access to PCI space and the BIOS code and
1911	  data regions.  This is sufficient for dosemu and X and all common
1912	  users of /dev/mem.
1913
1914	  If in doubt, say Y.
1915
1916config IO_STRICT_DEVMEM
1917	bool "Filter I/O access to /dev/mem"
1918	depends on STRICT_DEVMEM
1919	help
1920	  If this option is disabled, you allow userspace (root) access to all
1921	  io-memory regardless of whether a driver is actively using that
1922	  range.  Accidental access to this is obviously disastrous, but
1923	  specific access can be used by people debugging kernel drivers.
1924
1925	  If this option is switched on, the /dev/mem file only allows
1926	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1927	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1928	  if the driver using a given range cannot be disabled.
1929
1930	  If in doubt, say Y.
1931
1932menu "$(SRCARCH) Debugging"
1933
1934source "arch/$(SRCARCH)/Kconfig.debug"
1935
1936endmenu
1937
1938menu "Kernel Testing and Coverage"
1939
1940source "lib/kunit/Kconfig"
1941
1942config NOTIFIER_ERROR_INJECTION
1943	tristate "Notifier error injection"
1944	depends on DEBUG_KERNEL
1945	select DEBUG_FS
1946	help
1947	  This option provides the ability to inject artificial errors to
1948	  specified notifier chain callbacks. It is useful to test the error
1949	  handling of notifier call chain failures.
1950
1951	  Say N if unsure.
1952
1953config PM_NOTIFIER_ERROR_INJECT
1954	tristate "PM notifier error injection module"
1955	depends on PM && NOTIFIER_ERROR_INJECTION
1956	default m if PM_DEBUG
1957	help
1958	  This option provides the ability to inject artificial errors to
1959	  PM notifier chain callbacks.  It is controlled through debugfs
1960	  interface /sys/kernel/debug/notifier-error-inject/pm
1961
1962	  If the notifier call chain should be failed with some events
1963	  notified, write the error code to "actions/<notifier event>/error".
1964
1965	  Example: Inject PM suspend error (-12 = -ENOMEM)
1966
1967	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1968	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1969	  # echo mem > /sys/power/state
1970	  bash: echo: write error: Cannot allocate memory
1971
1972	  To compile this code as a module, choose M here: the module will
1973	  be called pm-notifier-error-inject.
1974
1975	  If unsure, say N.
1976
1977config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1978	tristate "OF reconfig notifier error injection module"
1979	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1980	help
1981	  This option provides the ability to inject artificial errors to
1982	  OF reconfig notifier chain callbacks.  It is controlled
1983	  through debugfs interface under
1984	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1985
1986	  If the notifier call chain should be failed with some events
1987	  notified, write the error code to "actions/<notifier event>/error".
1988
1989	  To compile this code as a module, choose M here: the module will
1990	  be called of-reconfig-notifier-error-inject.
1991
1992	  If unsure, say N.
1993
1994config NETDEV_NOTIFIER_ERROR_INJECT
1995	tristate "Netdev notifier error injection module"
1996	depends on NET && NOTIFIER_ERROR_INJECTION
1997	help
1998	  This option provides the ability to inject artificial errors to
1999	  netdevice notifier chain callbacks.  It is controlled through debugfs
2000	  interface /sys/kernel/debug/notifier-error-inject/netdev
2001
2002	  If the notifier call chain should be failed with some events
2003	  notified, write the error code to "actions/<notifier event>/error".
2004
2005	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
2006
2007	  # cd /sys/kernel/debug/notifier-error-inject/netdev
2008	  # echo -22 > actions/NETDEV_CHANGEMTU/error
2009	  # ip link set eth0 mtu 1024
2010	  RTNETLINK answers: Invalid argument
2011
2012	  To compile this code as a module, choose M here: the module will
2013	  be called netdev-notifier-error-inject.
2014
2015	  If unsure, say N.
2016
2017config FUNCTION_ERROR_INJECTION
2018	bool "Fault-injections of functions"
2019	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
2020	help
2021	  Add fault injections into various functions that are annotated with
2022	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
2023	  value of these functions. This is useful to test error paths of code.
2024
2025	  If unsure, say N
2026
2027config FAULT_INJECTION
2028	bool "Fault-injection framework"
2029	depends on DEBUG_KERNEL
2030	help
2031	  Provide fault-injection framework.
2032	  For more details, see Documentation/fault-injection/.
2033
2034config FAILSLAB
2035	bool "Fault-injection capability for kmalloc"
2036	depends on FAULT_INJECTION
2037	help
2038	  Provide fault-injection capability for kmalloc.
2039
2040config FAIL_PAGE_ALLOC
2041	bool "Fault-injection capability for alloc_pages()"
2042	depends on FAULT_INJECTION
2043	help
2044	  Provide fault-injection capability for alloc_pages().
2045
2046config FAULT_INJECTION_USERCOPY
2047	bool "Fault injection capability for usercopy functions"
2048	depends on FAULT_INJECTION
2049	help
2050	  Provides fault-injection capability to inject failures
2051	  in usercopy functions (copy_from_user(), get_user(), ...).
2052
2053config FAIL_MAKE_REQUEST
2054	bool "Fault-injection capability for disk IO"
2055	depends on FAULT_INJECTION && BLOCK
2056	help
2057	  Provide fault-injection capability for disk IO.
2058
2059config FAIL_IO_TIMEOUT
2060	bool "Fault-injection capability for faking disk interrupts"
2061	depends on FAULT_INJECTION && BLOCK
2062	help
2063	  Provide fault-injection capability on end IO handling. This
2064	  will make the block layer "forget" an interrupt as configured,
2065	  thus exercising the error handling.
2066
2067	  Only works with drivers that use the generic timeout handling,
2068	  for others it won't do anything.
2069
2070config FAIL_FUTEX
2071	bool "Fault-injection capability for futexes"
2072	select DEBUG_FS
2073	depends on FAULT_INJECTION && FUTEX
2074	help
2075	  Provide fault-injection capability for futexes.
2076
2077config FAULT_INJECTION_DEBUG_FS
2078	bool "Debugfs entries for fault-injection capabilities"
2079	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2080	help
2081	  Enable configuration of fault-injection capabilities via debugfs.
2082
2083config FAIL_FUNCTION
2084	bool "Fault-injection capability for functions"
2085	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2086	help
2087	  Provide function-based fault-injection capability.
2088	  This will allow you to override a specific function with a return
2089	  with given return value. As a result, function caller will see
2090	  an error value and have to handle it. This is useful to test the
2091	  error handling in various subsystems.
2092
2093config FAIL_MMC_REQUEST
2094	bool "Fault-injection capability for MMC IO"
2095	depends on FAULT_INJECTION_DEBUG_FS && MMC
2096	help
2097	  Provide fault-injection capability for MMC IO.
2098	  This will make the mmc core return data errors. This is
2099	  useful to test the error handling in the mmc block device
2100	  and to test how the mmc host driver handles retries from
2101	  the block device.
2102
2103config FAIL_SUNRPC
2104	bool "Fault-injection capability for SunRPC"
2105	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2106	help
2107	  Provide fault-injection capability for SunRPC and
2108	  its consumers.
2109
2110config FAULT_INJECTION_CONFIGFS
2111	bool "Configfs interface for fault-injection capabilities"
2112	depends on FAULT_INJECTION
2113	select CONFIGFS_FS
2114	help
2115	  This option allows configfs-based drivers to dynamically configure
2116	  fault-injection via configfs.  Each parameter for driver-specific
2117	  fault-injection can be made visible as a configfs attribute in a
2118	  configfs group.
2119
2120
2121config FAULT_INJECTION_STACKTRACE_FILTER
2122	bool "stacktrace filter for fault-injection capabilities"
2123	depends on FAULT_INJECTION
2124	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2125	select STACKTRACE
2126	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2127	help
2128	  Provide stacktrace filter for fault-injection capabilities
2129
2130config ARCH_HAS_KCOV
2131	bool
2132	help
2133	  An architecture should select this when it can successfully
2134	  build and run with CONFIG_KCOV. This typically requires
2135	  disabling instrumentation for some early boot code.
2136
2137config CC_HAS_SANCOV_TRACE_PC
2138	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2139
2140
2141config KCOV
2142	bool "Code coverage for fuzzing"
2143	depends on ARCH_HAS_KCOV
2144	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2145	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2146		   GCC_VERSION >= 120000 || CC_IS_CLANG
2147	select DEBUG_FS
2148	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2149	select OBJTOOL if HAVE_NOINSTR_HACK
2150	help
2151	  KCOV exposes kernel code coverage information in a form suitable
2152	  for coverage-guided fuzzing (randomized testing).
2153
2154	  For more details, see Documentation/dev-tools/kcov.rst.
2155
2156config KCOV_ENABLE_COMPARISONS
2157	bool "Enable comparison operands collection by KCOV"
2158	depends on KCOV
2159	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2160	help
2161	  KCOV also exposes operands of every comparison in the instrumented
2162	  code along with operand sizes and PCs of the comparison instructions.
2163	  These operands can be used by fuzzing engines to improve the quality
2164	  of fuzzing coverage.
2165
2166config KCOV_INSTRUMENT_ALL
2167	bool "Instrument all code by default"
2168	depends on KCOV
2169	default y
2170	help
2171	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2172	  then you will want to instrument the whole kernel and you should
2173	  say y here. If you are doing more targeted fuzzing (like e.g.
2174	  filesystem fuzzing with AFL) then you will want to enable coverage
2175	  for more specific subsets of files, and should say n here.
2176
2177config KCOV_IRQ_AREA_SIZE
2178	hex "Size of interrupt coverage collection area in words"
2179	depends on KCOV
2180	default 0x40000
2181	help
2182	  KCOV uses preallocated per-cpu areas to collect coverage from
2183	  soft interrupts. This specifies the size of those areas in the
2184	  number of unsigned long words.
2185
2186config KCOV_SELFTEST
2187	bool "Perform short selftests on boot"
2188	depends on KCOV
2189	help
2190	  Run short KCOV coverage collection selftests on boot.
2191	  On test failure, causes the kernel to panic. Recommended to be
2192	  enabled, ensuring critical functionality works as intended.
2193
2194menuconfig RUNTIME_TESTING_MENU
2195	bool "Runtime Testing"
2196	default y
2197
2198if RUNTIME_TESTING_MENU
2199
2200config TEST_DHRY
2201	tristate "Dhrystone benchmark test"
2202	help
2203	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2204	  calculates the number of Dhrystones per second, and the number of
2205	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2206	  by 1757 (the number of Dhrystones per second obtained on the VAX
2207	  11/780, nominally a 1 MIPS machine).
2208
2209	  To run the benchmark, it needs to be enabled explicitly, either from
2210	  the kernel command line (when built-in), or from userspace (when
2211	  built-in or modular).
2212
2213	  Run once during kernel boot:
2214
2215	      test_dhry.run
2216
2217	  Set number of iterations from kernel command line:
2218
2219	      test_dhry.iterations=<n>
2220
2221	  Set number of iterations from userspace:
2222
2223	      echo <n> > /sys/module/test_dhry/parameters/iterations
2224
2225	  Trigger manual run from userspace:
2226
2227	      echo y > /sys/module/test_dhry/parameters/run
2228
2229	  If the number of iterations is <= 0, the test will devise a suitable
2230	  number of iterations (test runs for at least 2s) automatically.
2231	  This process takes ca. 4s.
2232
2233	  If unsure, say N.
2234
2235config LKDTM
2236	tristate "Linux Kernel Dump Test Tool Module"
2237	depends on DEBUG_FS
2238	help
2239	This module enables testing of the different dumping mechanisms by
2240	inducing system failures at predefined crash points.
2241	If you don't need it: say N
2242	Choose M here to compile this code as a module. The module will be
2243	called lkdtm.
2244
2245	Documentation on how to use the module can be found in
2246	Documentation/fault-injection/provoke-crashes.rst
2247
2248config CPUMASK_KUNIT_TEST
2249	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2250	depends on KUNIT
2251	default KUNIT_ALL_TESTS
2252	help
2253	  Enable to turn on cpumask tests, running at boot or module load time.
2254
2255	  For more information on KUnit and unit tests in general, please refer
2256	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2257
2258	  If unsure, say N.
2259
2260config TEST_LIST_SORT
2261	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2262	depends on KUNIT
2263	default KUNIT_ALL_TESTS
2264	help
2265	  Enable this to turn on 'list_sort()' function test. This test is
2266	  executed only once during system boot (so affects only boot time),
2267	  or at module load time.
2268
2269	  If unsure, say N.
2270
2271config TEST_MIN_HEAP
2272	tristate "Min heap test"
2273	depends on DEBUG_KERNEL || m
2274	help
2275	  Enable this to turn on min heap function tests. 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_SORT
2282	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2283	depends on KUNIT
2284	default KUNIT_ALL_TESTS
2285	help
2286	  This option enables the self-test function of 'sort()' at boot,
2287	  or at module load time.
2288
2289	  If unsure, say N.
2290
2291config TEST_DIV64
2292	tristate "64bit/32bit division and modulo test"
2293	depends on DEBUG_KERNEL || m
2294	help
2295	  Enable this to turn on 'do_div()' function test. This test is
2296	  executed only once during system boot (so affects only boot time),
2297	  or at module load time.
2298
2299	  If unsure, say N.
2300
2301config TEST_MULDIV64
2302	tristate "mul_u64_u64_div_u64() test"
2303	depends on DEBUG_KERNEL || m
2304	help
2305	  Enable this to turn on 'mul_u64_u64_div_u64()' function test.
2306	  This test is executed only once during system boot (so affects
2307	  only boot time), or at module load time.
2308
2309	  If unsure, say N.
2310
2311config TEST_IOV_ITER
2312	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2313	depends on KUNIT
2314	depends on MMU
2315	default KUNIT_ALL_TESTS
2316	help
2317	  Enable this to turn on testing of the operation of the I/O iterator
2318	  (iov_iter). This test is executed only once during system boot (so
2319	  affects only boot time), or at module load time.
2320
2321	  If unsure, say N.
2322
2323config KPROBES_SANITY_TEST
2324	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2325	depends on DEBUG_KERNEL
2326	depends on KPROBES
2327	depends on KUNIT
2328	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2329	default KUNIT_ALL_TESTS
2330	help
2331	  This option provides for testing basic kprobes functionality on
2332	  boot. Samples of kprobe and kretprobe are inserted and
2333	  verified for functionality.
2334
2335	  Say N if you are unsure.
2336
2337config FPROBE_SANITY_TEST
2338	bool "Self test for fprobe"
2339	depends on DEBUG_KERNEL
2340	depends on FPROBE
2341	depends on KUNIT=y
2342	help
2343	  This option will enable testing the fprobe when the system boot.
2344	  A series of tests are made to verify that the fprobe is functioning
2345	  properly.
2346
2347	  Say N if you are unsure.
2348
2349config BACKTRACE_SELF_TEST
2350	tristate "Self test for the backtrace code"
2351	depends on DEBUG_KERNEL
2352	help
2353	  This option provides a kernel module that can be used to test
2354	  the kernel stack backtrace code. This option is not useful
2355	  for distributions or general kernels, but only for kernel
2356	  developers working on architecture code.
2357
2358	  Note that if you want to also test saved backtraces, you will
2359	  have to enable STACKTRACE as well.
2360
2361	  Say N if you are unsure.
2362
2363config TEST_REF_TRACKER
2364	tristate "Self test for reference tracker"
2365	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2366	select REF_TRACKER
2367	help
2368	  This option provides a kernel module performing tests
2369	  using reference tracker infrastructure.
2370
2371	  Say N if you are unsure.
2372
2373config RBTREE_TEST
2374	tristate "Red-Black tree test"
2375	depends on DEBUG_KERNEL
2376	help
2377	  A benchmark measuring the performance of the rbtree library.
2378	  Also includes rbtree invariant checks.
2379
2380config REED_SOLOMON_TEST
2381	tristate "Reed-Solomon library test"
2382	depends on DEBUG_KERNEL || m
2383	select REED_SOLOMON
2384	select REED_SOLOMON_ENC16
2385	select REED_SOLOMON_DEC16
2386	help
2387	  This option enables the self-test function of rslib at boot,
2388	  or at module load time.
2389
2390	  If unsure, say N.
2391
2392config INTERVAL_TREE_TEST
2393	tristate "Interval tree test"
2394	depends on DEBUG_KERNEL
2395	select INTERVAL_TREE
2396	help
2397	  A benchmark measuring the performance of the interval tree library
2398
2399config PERCPU_TEST
2400	tristate "Per cpu operations test"
2401	depends on m && DEBUG_KERNEL
2402	help
2403	  Enable this option to build test module which validates per-cpu
2404	  operations.
2405
2406	  If unsure, say N.
2407
2408config ATOMIC64_SELFTEST
2409	tristate "Perform an atomic64_t self-test"
2410	help
2411	  Enable this option to test the atomic64_t functions at boot or
2412	  at module load time.
2413
2414	  If unsure, say N.
2415
2416config ASYNC_RAID6_TEST
2417	tristate "Self test for hardware accelerated raid6 recovery"
2418	depends on ASYNC_RAID6_RECOV
2419	select ASYNC_MEMCPY
2420	help
2421	  This is a one-shot self test that permutes through the
2422	  recovery of all the possible two disk failure scenarios for a
2423	  N-disk array.  Recovery is performed with the asynchronous
2424	  raid6 recovery routines, and will optionally use an offload
2425	  engine if one is available.
2426
2427	  If unsure, say N.
2428
2429config TEST_HEXDUMP
2430	tristate "Test functions located in the hexdump module at runtime"
2431
2432config STRING_KUNIT_TEST
2433	tristate "KUnit test string functions at runtime" if !KUNIT_ALL_TESTS
2434	depends on KUNIT
2435	default KUNIT_ALL_TESTS
2436
2437config STRING_HELPERS_KUNIT_TEST
2438	tristate "KUnit test string helpers at runtime" if !KUNIT_ALL_TESTS
2439	depends on KUNIT
2440	default KUNIT_ALL_TESTS
2441
2442config TEST_KSTRTOX
2443	tristate "Test kstrto*() family of functions at runtime"
2444
2445config TEST_PRINTF
2446	tristate "Test printf() family of functions at runtime"
2447
2448config TEST_SCANF
2449	tristate "Test scanf() family of functions at runtime"
2450
2451config TEST_BITMAP
2452	tristate "Test bitmap_*() family of functions at runtime"
2453	help
2454	  Enable this option to test the bitmap functions at boot.
2455
2456	  If unsure, say N.
2457
2458config TEST_UUID
2459	tristate "Test functions located in the uuid module at runtime"
2460
2461config TEST_XARRAY
2462	tristate "Test the XArray code at runtime"
2463
2464config TEST_MAPLE_TREE
2465	tristate "Test the Maple Tree code at runtime or module load"
2466	help
2467	  Enable this option to test the maple tree code functions at boot, or
2468	  when the module is loaded. Enable "Debug Maple Trees" will enable
2469	  more verbose output on failures.
2470
2471	  If unsure, say N.
2472
2473config TEST_RHASHTABLE
2474	tristate "Perform selftest on resizable hash table"
2475	help
2476	  Enable this option to test the rhashtable functions at boot.
2477
2478	  If unsure, say N.
2479
2480config TEST_IDA
2481	tristate "Perform selftest on IDA functions"
2482
2483config TEST_PARMAN
2484	tristate "Perform selftest on priority array manager"
2485	depends on PARMAN
2486	help
2487	  Enable this option to test priority array manager on boot
2488	  (or module load).
2489
2490	  If unsure, say N.
2491
2492config TEST_IRQ_TIMINGS
2493	bool "IRQ timings selftest"
2494	depends on IRQ_TIMINGS
2495	help
2496	  Enable this option to test the irq timings code on boot.
2497
2498	  If unsure, say N.
2499
2500config TEST_LKM
2501	tristate "Test module loading with 'hello world' module"
2502	depends on m
2503	help
2504	  This builds the "test_module" module that emits "Hello, world"
2505	  on printk when loaded. It is designed to be used for basic
2506	  evaluation of the module loading subsystem (for example when
2507	  validating module verification). It lacks any extra dependencies,
2508	  and will not normally be loaded by the system unless explicitly
2509	  requested by name.
2510
2511	  If unsure, say N.
2512
2513config TEST_BITOPS
2514	tristate "Test module for compilation of bitops operations"
2515	help
2516	  This builds the "test_bitops" module that is much like the
2517	  TEST_LKM module except that it does a basic exercise of the
2518	  set/clear_bit macros and get_count_order/long to make sure there are
2519	  no compiler warnings from C=1 sparse checker or -Wextra
2520	  compilations. It has no dependencies and doesn't run or load unless
2521	  explicitly requested by name.  for example: modprobe test_bitops.
2522
2523	  If unsure, say N.
2524
2525config TEST_VMALLOC
2526	tristate "Test module for stress/performance analysis of vmalloc allocator"
2527	default n
2528       depends on MMU
2529	depends on m
2530	help
2531	  This builds the "test_vmalloc" module that should be used for
2532	  stress and performance analysis. So, any new change for vmalloc
2533	  subsystem can be evaluated from performance and stability point
2534	  of view.
2535
2536	  If unsure, say N.
2537
2538config TEST_BPF
2539	tristate "Test BPF filter functionality"
2540	depends on m && NET
2541	help
2542	  This builds the "test_bpf" module that runs various test vectors
2543	  against the BPF interpreter or BPF JIT compiler depending on the
2544	  current setting. This is in particular useful for BPF JIT compiler
2545	  development, but also to run regression tests against changes in
2546	  the interpreter code. It also enables test stubs for eBPF maps and
2547	  verifier used by user space verifier testsuite.
2548
2549	  If unsure, say N.
2550
2551config TEST_BLACKHOLE_DEV
2552	tristate "Test blackhole netdev functionality"
2553	depends on m && NET
2554	help
2555	  This builds the "test_blackhole_dev" module that validates the
2556	  data path through this blackhole netdev.
2557
2558	  If unsure, say N.
2559
2560config FIND_BIT_BENCHMARK
2561	tristate "Test find_bit functions"
2562	help
2563	  This builds the "test_find_bit" module that measure find_*_bit()
2564	  functions performance.
2565
2566	  If unsure, say N.
2567
2568config TEST_FIRMWARE
2569	tristate "Test firmware loading via userspace interface"
2570	depends on FW_LOADER
2571	help
2572	  This builds the "test_firmware" module that creates a userspace
2573	  interface for testing firmware loading. This can be used to
2574	  control the triggering of firmware loading without needing an
2575	  actual firmware-using device. The contents can be rechecked by
2576	  userspace.
2577
2578	  If unsure, say N.
2579
2580config TEST_SYSCTL
2581	tristate "sysctl test driver"
2582	depends on PROC_SYSCTL
2583	help
2584	  This builds the "test_sysctl" module. This driver enables to test the
2585	  proc sysctl interfaces available to drivers safely without affecting
2586	  production knobs which might alter system functionality.
2587
2588	  If unsure, say N.
2589
2590config BITFIELD_KUNIT
2591	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2592	depends on KUNIT
2593	default KUNIT_ALL_TESTS
2594	help
2595	  Enable this option to test the bitfield functions at boot.
2596
2597	  KUnit tests run during boot and output the results to the debug log
2598	  in TAP format (http://testanything.org/). Only useful for kernel devs
2599	  running the KUnit test harness, and not intended for inclusion into a
2600	  production build.
2601
2602	  For more information on KUnit and unit tests in general please refer
2603	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2604
2605	  If unsure, say N.
2606
2607config CHECKSUM_KUNIT
2608	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2609	depends on KUNIT
2610	default KUNIT_ALL_TESTS
2611	help
2612	  Enable this option to test the checksum functions at boot.
2613
2614	  KUnit tests run during boot and output the results to the debug log
2615	  in TAP format (http://testanything.org/). Only useful for kernel devs
2616	  running the KUnit test harness, and not intended for inclusion into a
2617	  production build.
2618
2619	  For more information on KUnit and unit tests in general please refer
2620	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2621
2622	  If unsure, say N.
2623
2624config HASH_KUNIT_TEST
2625	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2626	depends on KUNIT
2627	default KUNIT_ALL_TESTS
2628	help
2629	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2630	  integer (<linux/hash.h>) hash functions on boot.
2631
2632	  KUnit tests run during boot and output the results to the debug log
2633	  in TAP format (https://testanything.org/). Only useful for kernel devs
2634	  running the KUnit test harness, and not intended for inclusion into a
2635	  production build.
2636
2637	  For more information on KUnit and unit tests in general please refer
2638	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2639
2640	  This is intended to help people writing architecture-specific
2641	  optimized versions. If unsure, say N.
2642
2643config RESOURCE_KUNIT_TEST
2644	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2645	depends on KUNIT
2646	default KUNIT_ALL_TESTS
2647	select GET_FREE_REGION
2648	help
2649	  This builds the resource API unit test.
2650	  Tests the logic of API provided by resource.c and ioport.h.
2651	  For more information on KUnit and unit tests in general please refer
2652	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2653
2654	  If unsure, say N.
2655
2656config SYSCTL_KUNIT_TEST
2657	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2658	depends on KUNIT
2659	default KUNIT_ALL_TESTS
2660	help
2661	  This builds the proc sysctl unit test, which runs on boot.
2662	  Tests the API contract and implementation correctness of sysctl.
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 LIST_KUNIT_TEST
2669	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2670	depends on KUNIT
2671	default KUNIT_ALL_TESTS
2672	help
2673	  This builds the linked list KUnit test suite.
2674	  It tests that the API and basic functionality of the list_head type
2675	  and associated macros.
2676
2677	  KUnit tests run during boot and output the results to the debug log
2678	  in TAP format (https://testanything.org/). Only useful for kernel devs
2679	  running the KUnit test harness, and not intended for inclusion into a
2680	  production build.
2681
2682	  For more information on KUnit and unit tests in general please refer
2683	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2684
2685	  If unsure, say N.
2686
2687config HASHTABLE_KUNIT_TEST
2688	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2689	depends on KUNIT
2690	default KUNIT_ALL_TESTS
2691	help
2692	  This builds the hashtable KUnit test suite.
2693	  It tests the basic functionality of the API defined in
2694	  include/linux/hashtable.h. For more information on KUnit and
2695	  unit tests in general please refer to the KUnit documentation
2696	  in Documentation/dev-tools/kunit/.
2697
2698	  If unsure, say N.
2699
2700config LINEAR_RANGES_TEST
2701	tristate "KUnit test for linear_ranges"
2702	depends on KUNIT
2703	select LINEAR_RANGES
2704	help
2705	  This builds the linear_ranges unit test, which runs on boot.
2706	  Tests the linear_ranges logic correctness.
2707	  For more information on KUnit and unit tests in general please refer
2708	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2709
2710	  If unsure, say N.
2711
2712config CMDLINE_KUNIT_TEST
2713	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2714	depends on KUNIT
2715	default KUNIT_ALL_TESTS
2716	help
2717	  This builds the cmdline API unit test.
2718	  Tests the logic of API provided by cmdline.c.
2719	  For more information on KUnit and unit tests in general please refer
2720	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2721
2722	  If unsure, say N.
2723
2724config BITS_TEST
2725	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2726	depends on KUNIT
2727	default KUNIT_ALL_TESTS
2728	help
2729	  This builds the bits unit test.
2730	  Tests the logic of macros defined in bits.h.
2731	  For more information on KUnit and unit tests in general please refer
2732	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2733
2734	  If unsure, say N.
2735
2736config SLUB_KUNIT_TEST
2737	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2738	depends on SLUB_DEBUG && KUNIT
2739	default KUNIT_ALL_TESTS
2740	help
2741	  This builds SLUB allocator unit test.
2742	  Tests SLUB cache debugging functionality.
2743	  For more information on KUnit and unit tests in general please refer
2744	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2745
2746	  If unsure, say N.
2747
2748config RATIONAL_KUNIT_TEST
2749	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2750	depends on KUNIT && RATIONAL
2751	default KUNIT_ALL_TESTS
2752	help
2753	  This builds the rational math unit test.
2754	  For more information on KUnit and unit tests in general please refer
2755	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2756
2757	  If unsure, say N.
2758
2759config MEMCPY_KUNIT_TEST
2760	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2761	depends on KUNIT
2762	default KUNIT_ALL_TESTS
2763	help
2764	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2765	  For more information on KUnit and unit tests in general please refer
2766	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2767
2768	  If unsure, say N.
2769
2770config IS_SIGNED_TYPE_KUNIT_TEST
2771	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2772	depends on KUNIT
2773	default KUNIT_ALL_TESTS
2774	help
2775	  Builds unit tests for the is_signed_type() macro.
2776
2777	  For more information on KUnit and unit tests in general please refer
2778	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2779
2780	  If unsure, say N.
2781
2782config OVERFLOW_KUNIT_TEST
2783	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2784	depends on KUNIT
2785	default KUNIT_ALL_TESTS
2786	help
2787	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2788	  related functions.
2789
2790	  For more information on KUnit and unit tests in general please refer
2791	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2792
2793	  If unsure, say N.
2794
2795config STACKINIT_KUNIT_TEST
2796	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2797	depends on KUNIT
2798	default KUNIT_ALL_TESTS
2799	help
2800	  Test if the kernel is zero-initializing stack variables and
2801	  padding. Coverage is controlled by compiler flags,
2802	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2803	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2804	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2805
2806config FORTIFY_KUNIT_TEST
2807	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2808	depends on KUNIT
2809	default KUNIT_ALL_TESTS
2810	help
2811	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2812	  by the str*() and mem*() family of functions. For testing runtime
2813	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2814
2815config HW_BREAKPOINT_KUNIT_TEST
2816	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2817	depends on HAVE_HW_BREAKPOINT
2818	depends on KUNIT=y
2819	default KUNIT_ALL_TESTS
2820	help
2821	  Tests for hw_breakpoint constraints accounting.
2822
2823	  If unsure, say N.
2824
2825config SIPHASH_KUNIT_TEST
2826	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2827	depends on KUNIT
2828	default KUNIT_ALL_TESTS
2829	help
2830	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2831	  functions on boot (or module load).
2832
2833	  This is intended to help people writing architecture-specific
2834	  optimized versions.  If unsure, say N.
2835
2836config USERCOPY_KUNIT_TEST
2837	tristate "KUnit Test for user/kernel boundary protections"
2838	depends on KUNIT
2839	default KUNIT_ALL_TESTS
2840	help
2841	  This builds the "usercopy_kunit" module that runs sanity checks
2842	  on the copy_to/from_user infrastructure, making sure basic
2843	  user/kernel boundary testing is working.
2844
2845config TEST_UDELAY
2846	tristate "udelay test driver"
2847	help
2848	  This builds the "udelay_test" module that helps to make sure
2849	  that udelay() is working properly.
2850
2851	  If unsure, say N.
2852
2853config TEST_STATIC_KEYS
2854	tristate "Test static keys"
2855	depends on m
2856	help
2857	  Test the static key interfaces.
2858
2859	  If unsure, say N.
2860
2861config TEST_DYNAMIC_DEBUG
2862	tristate "Test DYNAMIC_DEBUG"
2863	depends on DYNAMIC_DEBUG
2864	help
2865	  This module registers a tracer callback to count enabled
2866	  pr_debugs in a 'do_debugging' function, then alters their
2867	  enablements, calls the function, and compares counts.
2868
2869	  If unsure, say N.
2870
2871config TEST_KMOD
2872	tristate "kmod stress tester"
2873	depends on m
2874	depends on NETDEVICES && NET_CORE && INET # for TUN
2875	depends on BLOCK
2876	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2877	select TEST_LKM
2878	select XFS_FS
2879	select TUN
2880	select BTRFS_FS
2881	help
2882	  Test the kernel's module loading mechanism: kmod. kmod implements
2883	  support to load modules using the Linux kernel's usermode helper.
2884	  This test provides a series of tests against kmod.
2885
2886	  Although technically you can either build test_kmod as a module or
2887	  into the kernel we disallow building it into the kernel since
2888	  it stress tests request_module() and this will very likely cause
2889	  some issues by taking over precious threads available from other
2890	  module load requests, ultimately this could be fatal.
2891
2892	  To run tests run:
2893
2894	  tools/testing/selftests/kmod/kmod.sh --help
2895
2896	  If unsure, say N.
2897
2898config TEST_DEBUG_VIRTUAL
2899	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2900	depends on DEBUG_VIRTUAL
2901	help
2902	  Test the kernel's ability to detect incorrect calls to
2903	  virt_to_phys() done against the non-linear part of the
2904	  kernel's virtual address map.
2905
2906	  If unsure, say N.
2907
2908config TEST_MEMCAT_P
2909	tristate "Test memcat_p() helper function"
2910	help
2911	  Test the memcat_p() helper for correctly merging two
2912	  pointer arrays together.
2913
2914	  If unsure, say N.
2915
2916config TEST_OBJAGG
2917	tristate "Perform selftest on object aggreration manager"
2918	default n
2919	depends on OBJAGG
2920	help
2921	  Enable this option to test object aggregation manager on boot
2922	  (or module load).
2923
2924config TEST_MEMINIT
2925	tristate "Test heap/page initialization"
2926	help
2927	  Test if the kernel is zero-initializing heap and page allocations.
2928	  This can be useful to test init_on_alloc and init_on_free features.
2929
2930	  If unsure, say N.
2931
2932config TEST_HMM
2933	tristate "Test HMM (Heterogeneous Memory Management)"
2934	depends on TRANSPARENT_HUGEPAGE
2935	depends on DEVICE_PRIVATE
2936	select HMM_MIRROR
2937	select MMU_NOTIFIER
2938	help
2939	  This is a pseudo device driver solely for testing HMM.
2940	  Say M here if you want to build the HMM test module.
2941	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2942
2943	  If unsure, say N.
2944
2945config TEST_FREE_PAGES
2946	tristate "Test freeing pages"
2947	help
2948	  Test that a memory leak does not occur due to a race between
2949	  freeing a block of pages and a speculative page reference.
2950	  Loading this module is safe if your kernel has the bug fixed.
2951	  If the bug is not fixed, it will leak gigabytes of memory and
2952	  probably OOM your system.
2953
2954config TEST_FPU
2955	tristate "Test floating point operations in kernel space"
2956	depends on ARCH_HAS_KERNEL_FPU_SUPPORT && !KCOV_INSTRUMENT_ALL
2957	help
2958	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2959	  which will trigger a sequence of floating point operations. This is used
2960	  for self-testing floating point control register setting in
2961	  kernel_fpu_begin().
2962
2963	  If unsure, say N.
2964
2965config TEST_CLOCKSOURCE_WATCHDOG
2966	tristate "Test clocksource watchdog in kernel space"
2967	depends on CLOCKSOURCE_WATCHDOG
2968	help
2969	  Enable this option to create a kernel module that will trigger
2970	  a test of the clocksource watchdog.  This module may be loaded
2971	  via modprobe or insmod in which case it will run upon being
2972	  loaded, or it may be built in, in which case it will run
2973	  shortly after boot.
2974
2975	  If unsure, say N.
2976
2977config TEST_OBJPOOL
2978	tristate "Test module for correctness and stress of objpool"
2979	default n
2980	depends on m && DEBUG_KERNEL
2981	help
2982	  This builds the "test_objpool" module that should be used for
2983	  correctness verification and concurrent testings of objects
2984	  allocation and reclamation.
2985
2986	  If unsure, say N.
2987
2988endif # RUNTIME_TESTING_MENU
2989
2990config ARCH_USE_MEMTEST
2991	bool
2992	help
2993	  An architecture should select this when it uses early_memtest()
2994	  during boot process.
2995
2996config MEMTEST
2997	bool "Memtest"
2998	depends on ARCH_USE_MEMTEST
2999	help
3000	  This option adds a kernel parameter 'memtest', which allows memtest
3001	  to be set and executed.
3002	        memtest=0, mean disabled; -- default
3003	        memtest=1, mean do 1 test pattern;
3004	        ...
3005	        memtest=17, mean do 17 test patterns.
3006	  If you are unsure how to answer this question, answer N.
3007
3008
3009
3010config HYPERV_TESTING
3011	bool "Microsoft Hyper-V driver testing"
3012	default n
3013	depends on HYPERV && DEBUG_FS
3014	help
3015	  Select this option to enable Hyper-V vmbus testing.
3016
3017endmenu # "Kernel Testing and Coverage"
3018
3019menu "Rust hacking"
3020
3021config RUST_DEBUG_ASSERTIONS
3022	bool "Debug assertions"
3023	depends on RUST
3024	help
3025	  Enables rustc's `-Cdebug-assertions` codegen option.
3026
3027	  This flag lets you turn `cfg(debug_assertions)` conditional
3028	  compilation on or off. This can be used to enable extra debugging
3029	  code in development but not in production. For example, it controls
3030	  the behavior of the standard library's `debug_assert!` macro.
3031
3032	  Note that this will apply to all Rust code, including `core`.
3033
3034	  If unsure, say N.
3035
3036config RUST_OVERFLOW_CHECKS
3037	bool "Overflow checks"
3038	default y
3039	depends on RUST
3040	help
3041	  Enables rustc's `-Coverflow-checks` codegen option.
3042
3043	  This flag allows you to control the behavior of runtime integer
3044	  overflow. When overflow-checks are enabled, a Rust panic will occur
3045	  on overflow.
3046
3047	  Note that this will apply to all Rust code, including `core`.
3048
3049	  If unsure, say Y.
3050
3051config RUST_BUILD_ASSERT_ALLOW
3052	bool "Allow unoptimized build-time assertions"
3053	depends on RUST
3054	help
3055	  Controls how are `build_error!` and `build_assert!` handled during build.
3056
3057	  If calls to them exist in the binary, it may indicate a violated invariant
3058	  or that the optimizer failed to verify the invariant during compilation.
3059
3060	  This should not happen, thus by default the build is aborted. However,
3061	  as an escape hatch, you can choose Y here to ignore them during build
3062	  and let the check be carried at runtime (with `panic!` being called if
3063	  the check fails).
3064
3065	  If unsure, say N.
3066
3067config RUST_KERNEL_DOCTESTS
3068	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3069	depends on RUST && KUNIT=y
3070	default KUNIT_ALL_TESTS
3071	help
3072	  This builds the documentation tests of the `kernel` crate
3073	  as KUnit tests.
3074
3075	  For more information on KUnit and unit tests in general,
3076	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3077
3078	  If unsure, say N.
3079
3080endmenu # "Rust"
3081
3082endmenu # Kernel hacking
3083
3084config INT_POW_TEST
3085	tristate "Integer exponentiation (int_pow) test" if !KUNIT_ALL_TESTS
3086	depends on KUNIT
3087	default KUNIT_ALL_TESTS
3088	help
3089	  This option enables the KUnit test suite for the int_pow function,
3090	  which performs integer exponentiation. The test suite is designed to
3091	  verify that the implementation of int_pow correctly computes the power
3092	  of a given base raised to a given exponent.
3093
3094	  Enabling this option will include tests that check various scenarios
3095	  and edge cases to ensure the accuracy and reliability of the exponentiation
3096	  function.
3097
3098	  If unsure, say N
3099