xref: /linux/lib/Kconfig.debug (revision 2d7f3d1a5866705be2393150e1ffdf67030ab88d)
1# SPDX-License-Identifier: GPL-2.0-only
2menu "Kernel hacking"
3
4menu "printk and dmesg options"
5
6config PRINTK_TIME
7	bool "Show timing information on printks"
8	depends on PRINTK
9	help
10	  Selecting this option causes time stamps of the printk()
11	  messages to be added to the output of the syslog() system
12	  call and at the console.
13
14	  The timestamp is always recorded internally, and exported
15	  to /dev/kmsg. This flag just specifies if the timestamp should
16	  be included, not that the timestamp is recorded.
17
18	  The behavior is also controlled by the kernel command line
19	  parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
20
21config PRINTK_CALLER
22	bool "Show caller information on printks"
23	depends on PRINTK
24	help
25	  Selecting this option causes printk() to add a caller "thread id" (if
26	  in task context) or a caller "processor id" (if not in task context)
27	  to every message.
28
29	  This option is intended for environments where multiple threads
30	  concurrently call printk() for many times, for it is difficult to
31	  interpret without knowing where these lines (or sometimes individual
32	  line which was divided into multiple lines due to race) came from.
33
34	  Since toggling after boot makes the code racy, currently there is
35	  no option to enable/disable at the kernel command line parameter or
36	  sysfs interface.
37
38config STACKTRACE_BUILD_ID
39	bool "Show build ID information in stacktraces"
40	depends on PRINTK
41	help
42	  Selecting this option adds build ID information for symbols in
43	  stacktraces printed with the printk format '%p[SR]b'.
44
45	  This option is intended for distros where debuginfo is not easily
46	  accessible but can be downloaded given the build ID of the vmlinux or
47	  kernel module where the function is located.
48
49config CONSOLE_LOGLEVEL_DEFAULT
50	int "Default console loglevel (1-15)"
51	range 1 15
52	default "7"
53	help
54	  Default loglevel to determine what will be printed on the console.
55
56	  Setting a default here is equivalent to passing in loglevel=<x> in
57	  the kernel bootargs. loglevel=<x> continues to override whatever
58	  value is specified here as well.
59
60	  Note: This does not affect the log level of un-prefixed printk()
61	  usage in the kernel. That is controlled by the MESSAGE_LOGLEVEL_DEFAULT
62	  option.
63
64config CONSOLE_LOGLEVEL_QUIET
65	int "quiet console loglevel (1-15)"
66	range 1 15
67	default "4"
68	help
69	  loglevel to use when "quiet" is passed on the kernel commandline.
70
71	  When "quiet" is passed on the kernel commandline this loglevel
72	  will be used as the loglevel. IOW passing "quiet" will be the
73	  equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
74
75config MESSAGE_LOGLEVEL_DEFAULT
76	int "Default message log level (1-7)"
77	range 1 7
78	default "4"
79	help
80	  Default log level for printk statements with no specified priority.
81
82	  This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
83	  that are auditing their logs closely may want to set it to a lower
84	  priority.
85
86	  Note: This does not affect what message level gets printed on the console
87	  by default. To change that, use loglevel=<x> in the kernel bootargs,
88	  or pick a different CONSOLE_LOGLEVEL_DEFAULT configuration value.
89
90config BOOT_PRINTK_DELAY
91	bool "Delay each boot printk message by N milliseconds"
92	depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
93	help
94	  This build option allows you to read kernel boot messages
95	  by inserting a short delay after each one.  The delay is
96	  specified in milliseconds on the kernel command line,
97	  using "boot_delay=N".
98
99	  It is likely that you would also need to use "lpj=M" to preset
100	  the "loops per jiffie" value.
101	  See a previous boot log for the "lpj" value to use for your
102	  system, and then set "lpj=M" before setting "boot_delay=N".
103	  NOTE:  Using this option may adversely affect SMP systems.
104	  I.e., processors other than the first one may not boot up.
105	  BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
106	  what it believes to be lockup conditions.
107
108config DYNAMIC_DEBUG
109	bool "Enable dynamic printk() support"
110	default n
111	depends on PRINTK
112	depends on (DEBUG_FS || PROC_FS)
113	select DYNAMIC_DEBUG_CORE
114	help
115
116	  Compiles debug level messages into the kernel, which would not
117	  otherwise be available at runtime. These messages can then be
118	  enabled/disabled based on various levels of scope - per source file,
119	  function, module, format string, and line number. This mechanism
120	  implicitly compiles in all pr_debug() and dev_dbg() calls, which
121	  enlarges the kernel text size by about 2%.
122
123	  If a source file is compiled with DEBUG flag set, any
124	  pr_debug() calls in it are enabled by default, but can be
125	  disabled at runtime as below.  Note that DEBUG flag is
126	  turned on by many CONFIG_*DEBUG* options.
127
128	  Usage:
129
130	  Dynamic debugging is controlled via the 'dynamic_debug/control' file,
131	  which is contained in the 'debugfs' filesystem or procfs.
132	  Thus, the debugfs or procfs filesystem must first be mounted before
133	  making use of this feature.
134	  We refer the control file as: <debugfs>/dynamic_debug/control. This
135	  file contains a list of the debug statements that can be enabled. The
136	  format for each line of the file is:
137
138		filename:lineno [module]function flags format
139
140	  filename : source file of the debug statement
141	  lineno : line number of the debug statement
142	  module : module that contains the debug statement
143	  function : function that contains the debug statement
144	  flags : '=p' means the line is turned 'on' for printing
145	  format : the format used for the debug statement
146
147	  From a live system:
148
149		nullarbor:~ # cat <debugfs>/dynamic_debug/control
150		# filename:lineno [module]function flags format
151		fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
152		fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
153		fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
154
155	  Example usage:
156
157		// enable the message at line 1603 of file svcsock.c
158		nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
159						<debugfs>/dynamic_debug/control
160
161		// enable all the messages in file svcsock.c
162		nullarbor:~ # echo -n 'file svcsock.c +p' >
163						<debugfs>/dynamic_debug/control
164
165		// enable all the messages in the NFS server module
166		nullarbor:~ # echo -n 'module nfsd +p' >
167						<debugfs>/dynamic_debug/control
168
169		// enable all 12 messages in the function svc_process()
170		nullarbor:~ # echo -n 'func svc_process +p' >
171						<debugfs>/dynamic_debug/control
172
173		// disable all 12 messages in the function svc_process()
174		nullarbor:~ # echo -n 'func svc_process -p' >
175						<debugfs>/dynamic_debug/control
176
177	  See Documentation/admin-guide/dynamic-debug-howto.rst for additional
178	  information.
179
180config DYNAMIC_DEBUG_CORE
181	bool "Enable core function of dynamic debug support"
182	depends on PRINTK
183	depends on (DEBUG_FS || PROC_FS)
184	help
185	  Enable core functional support of dynamic debug. It is useful
186	  when you want to tie dynamic debug to your kernel modules with
187	  DYNAMIC_DEBUG_MODULE defined for each of them, especially for
188	  the case of embedded system where the kernel image size is
189	  sensitive for people.
190
191config SYMBOLIC_ERRNAME
192	bool "Support symbolic error names in printf"
193	default y if PRINTK
194	help
195	  If you say Y here, the kernel's printf implementation will
196	  be able to print symbolic error names such as ENOSPC instead
197	  of the number 28. It makes the kernel image slightly larger
198	  (about 3KB), but can make the kernel logs easier to read.
199
200config DEBUG_BUGVERBOSE
201	bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
202	depends on BUG && (GENERIC_BUG || HAVE_DEBUG_BUGVERBOSE)
203	default y
204	help
205	  Say Y here to make BUG() panics output the file name and line number
206	  of the BUG call as well as the EIP and oops trace.  This aids
207	  debugging but costs about 70-100K of memory.
208
209endmenu # "printk and dmesg options"
210
211config DEBUG_KERNEL
212	bool "Kernel debugging"
213	help
214	  Say Y here if you are developing drivers or trying to debug and
215	  identify kernel problems.
216
217config DEBUG_MISC
218	bool "Miscellaneous debug code"
219	default DEBUG_KERNEL
220	depends on DEBUG_KERNEL
221	help
222	  Say Y here if you need to enable miscellaneous debug code that should
223	  be under a more specific debug option but isn't.
224
225menu "Compile-time checks and compiler options"
226
227config DEBUG_INFO
228	bool
229	help
230	  A kernel debug info option other than "None" has been selected
231	  in the "Debug information" choice below, indicating that debug
232	  information will be generated for build targets.
233
234# Clang generates .uleb128 with label differences for DWARF v5, a feature that
235# older binutils ports do not support when utilizing RISC-V style linker
236# relaxation: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
237config AS_HAS_NON_CONST_ULEB128
238	def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
239
240choice
241	prompt "Debug information"
242	depends on DEBUG_KERNEL
243	help
244	  Selecting something other than "None" results in a kernel image
245	  that will include debugging info resulting in a larger kernel image.
246	  This adds debug symbols to the kernel and modules (gcc -g), and
247	  is needed if you intend to use kernel crashdump or binary object
248	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
249
250	  Choose which version of DWARF debug info to emit. If unsure,
251	  select "Toolchain default".
252
253config DEBUG_INFO_NONE
254	bool "Disable debug information"
255	help
256	  Do not build the kernel with debugging information, which will
257	  result in a faster and smaller build.
258
259config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
260	bool "Rely on the toolchain's implicit default DWARF version"
261	select DEBUG_INFO
262	depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
263	help
264	  The implicit default version of DWARF debug info produced by a
265	  toolchain changes over time.
266
267	  This can break consumers of the debug info that haven't upgraded to
268	  support newer revisions, and prevent testing newer versions, but
269	  those should be less common scenarios.
270
271config DEBUG_INFO_DWARF4
272	bool "Generate DWARF Version 4 debuginfo"
273	select DEBUG_INFO
274	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
275	help
276	  Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
277	  if using clang without clang's integrated assembler, and gdb 7.0+.
278
279	  If you have consumers of DWARF debug info that are not ready for
280	  newer revisions of DWARF, you may wish to choose this or have your
281	  config select this.
282
283config DEBUG_INFO_DWARF5
284	bool "Generate DWARF Version 5 debuginfo"
285	select DEBUG_INFO
286	depends on !ARCH_HAS_BROKEN_DWARF5
287	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_ULEB128)
288	help
289	  Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
290	  5.0+ accepts the -gdwarf-5 flag but only had partial support for some
291	  draft features until 7.0), and gdb 8.0+.
292
293	  Changes to the structure of debug info in Version 5 allow for around
294	  15-18% savings in resulting image and debug info section sizes as
295	  compared to DWARF Version 4. DWARF Version 5 standardizes previous
296	  extensions such as accelerators for symbol indexing and the format
297	  for fission (.dwo/.dwp) files. Users may not want to select this
298	  config if they rely on tooling that has not yet been updated to
299	  support DWARF Version 5.
300
301endchoice # "Debug information"
302
303if DEBUG_INFO
304
305config DEBUG_INFO_REDUCED
306	bool "Reduce debugging information"
307	help
308	  If you say Y here gcc is instructed to generate less debugging
309	  information for structure types. This means that tools that
310	  need full debugging information (like kgdb or systemtap) won't
311	  be happy. But if you merely need debugging information to
312	  resolve line numbers there is no loss. Advantage is that
313	  build directory object sizes shrink dramatically over a full
314	  DEBUG_INFO build and compile times are reduced too.
315	  Only works with newer gcc versions.
316
317choice
318	prompt "Compressed Debug information"
319	help
320	  Compress the resulting debug info. Results in smaller debug info sections,
321	  but requires that consumers are able to decompress the results.
322
323	  If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
324
325config DEBUG_INFO_COMPRESSED_NONE
326	bool "Don't compress debug information"
327	help
328	  Don't compress debug info sections.
329
330config DEBUG_INFO_COMPRESSED_ZLIB
331	bool "Compress debugging information with zlib"
332	depends on $(cc-option,-gz=zlib)
333	depends on $(ld-option,--compress-debug-sections=zlib)
334	help
335	  Compress the debug information using zlib.  Requires GCC 5.0+ or Clang
336	  5.0+, binutils 2.26+, and zlib.
337
338	  Users of dpkg-deb via scripts/package/builddeb may find an increase in
339	  size of their debug .deb packages with this config set, due to the
340	  debug info being compressed with zlib, then the object files being
341	  recompressed with a different compression scheme. But this is still
342	  preferable to setting $KDEB_COMPRESS to "none" which would be even
343	  larger.
344
345config DEBUG_INFO_COMPRESSED_ZSTD
346	bool "Compress debugging information with zstd"
347	depends on $(cc-option,-gz=zstd)
348	depends on $(ld-option,--compress-debug-sections=zstd)
349	help
350	  Compress the debug information using zstd.  This may provide better
351	  compression than zlib, for about the same time costs, but requires newer
352	  toolchain support.  Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
353	  zstd.
354
355endchoice # "Compressed Debug information"
356
357config DEBUG_INFO_SPLIT
358	bool "Produce split debuginfo in .dwo files"
359	depends on $(cc-option,-gsplit-dwarf)
360	# RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
361	# prior to 12.x:
362	# https://github.com/llvm/llvm-project/issues/56642
363	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
364	depends on !RISCV || GCC_VERSION >= 120000
365	help
366	  Generate debug info into separate .dwo files. This significantly
367	  reduces the build directory size for builds with DEBUG_INFO,
368	  because it stores the information only once on disk in .dwo
369	  files instead of multiple times in object files and executables.
370	  In addition the debug information is also compressed.
371
372	  Requires recent gcc (4.7+) and recent gdb/binutils.
373	  Any tool that packages or reads debug information would need
374	  to know about the .dwo files and include them.
375	  Incompatible with older versions of ccache.
376
377config DEBUG_INFO_BTF
378	bool "Generate BTF typeinfo"
379	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
380	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
381	depends on BPF_SYSCALL
382	depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
383	# pahole uses elfutils, which does not have support for Hexagon relocations
384	depends on !HEXAGON
385	help
386	  Generate deduplicated BTF type information from DWARF debug info.
387	  Turning this on expects presence of pahole tool, which will convert
388	  DWARF type info into equivalent deduplicated BTF type info.
389
390config PAHOLE_HAS_SPLIT_BTF
391	def_bool PAHOLE_VERSION >= 119
392
393config PAHOLE_HAS_BTF_TAG
394	def_bool PAHOLE_VERSION >= 123
395	depends on CC_IS_CLANG
396	help
397	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
398	  btf_decl_tag) or not. Currently only clang compiler implements
399	  these attributes, so make the config depend on CC_IS_CLANG.
400
401config PAHOLE_HAS_LANG_EXCLUDE
402	def_bool PAHOLE_VERSION >= 124
403	help
404	  Support for the --lang_exclude flag which makes pahole exclude
405	  compilation units from the supplied language. Used in Kbuild to
406	  omit Rust CUs which are not supported in version 1.24 of pahole,
407	  otherwise it would emit malformed kernel and module binaries when
408	  using DEBUG_INFO_BTF_MODULES.
409
410config DEBUG_INFO_BTF_MODULES
411	def_bool y
412	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
413	help
414	  Generate compact split BTF type information for kernel modules.
415
416config MODULE_ALLOW_BTF_MISMATCH
417	bool "Allow loading modules with non-matching BTF type info"
418	depends on DEBUG_INFO_BTF_MODULES
419	help
420	  For modules whose split BTF does not match vmlinux, load without
421	  BTF rather than refusing to load. The default behavior with
422	  module BTF enabled is to reject modules with such mismatches;
423	  this option will still load module BTF where possible but ignore
424	  it when a mismatch is found.
425
426config GDB_SCRIPTS
427	bool "Provide GDB scripts for kernel debugging"
428	help
429	  This creates the required links to GDB helper scripts in the
430	  build directory. If you load vmlinux into gdb, the helper
431	  scripts will be automatically imported by gdb as well, and
432	  additional functions are available to analyze a Linux kernel
433	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
434	  for further details.
435
436endif # DEBUG_INFO
437
438config FRAME_WARN
439	int "Warn for stack frames larger than"
440	range 0 8192
441	default 0 if KMSAN
442	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
443	default 2048 if PARISC
444	default 1536 if (!64BIT && XTENSA)
445	default 1280 if KASAN && !64BIT
446	default 1024 if !64BIT
447	default 2048 if 64BIT
448	help
449	  Tell the compiler to warn at build time for stack frames larger than this.
450	  Setting this too low will cause a lot of warnings.
451	  Setting it to 0 disables the warning.
452
453config STRIP_ASM_SYMS
454	bool "Strip assembler-generated symbols during link"
455	default n
456	help
457	  Strip internal assembler-generated symbols during a link (symbols
458	  that look like '.Lxxx') so they don't pollute the output of
459	  get_wchan() and suchlike.
460
461config READABLE_ASM
462	bool "Generate readable assembler code"
463	depends on DEBUG_KERNEL
464	depends on CC_IS_GCC
465	help
466	  Disable some compiler optimizations that tend to generate human unreadable
467	  assembler output. This may make the kernel slightly slower, but it helps
468	  to keep kernel developers who have to stare a lot at assembler listings
469	  sane.
470
471config HEADERS_INSTALL
472	bool "Install uapi headers to usr/include"
473	depends on !UML
474	help
475	  This option will install uapi headers (headers exported to user-space)
476	  into the usr/include directory for use during the kernel build.
477	  This is unneeded for building the kernel itself, but needed for some
478	  user-space program samples. It is also needed by some features such
479	  as uapi header sanity checks.
480
481config DEBUG_SECTION_MISMATCH
482	bool "Enable full Section mismatch analysis"
483	depends on CC_IS_GCC
484	help
485	  The section mismatch analysis checks if there are illegal
486	  references from one section to another section.
487	  During linktime or runtime, some sections are dropped;
488	  any use of code/data previously in these sections would
489	  most likely result in an oops.
490	  In the code, functions and variables are annotated with
491	  __init,, etc. (see the full list in include/linux/init.h),
492	  which results in the code/data being placed in specific sections.
493	  The section mismatch analysis is always performed after a full
494	  kernel build, and enabling this option causes the following
495	  additional step to occur:
496	  - Add the option -fno-inline-functions-called-once to gcc commands.
497	    When inlining a function annotated with __init in a non-init
498	    function, we would lose the section information and thus
499	    the analysis would not catch the illegal reference.
500	    This option tells gcc to inline less (but it does result in
501	    a larger kernel).
502
503config SECTION_MISMATCH_WARN_ONLY
504	bool "Make section mismatch errors non-fatal"
505	default y
506	help
507	  If you say N here, the build process will fail if there are any
508	  section mismatch, instead of just throwing warnings.
509
510	  If unsure, say Y.
511
512config DEBUG_FORCE_FUNCTION_ALIGN_64B
513	bool "Force all function address 64B aligned"
514	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
515	select FUNCTION_ALIGNMENT_64B
516	help
517	  There are cases that a commit from one domain changes the function
518	  address alignment of other domains, and cause magic performance
519	  bump (regression or improvement). Enable this option will help to
520	  verify if the bump is caused by function alignment changes, while
521	  it will slightly increase the kernel size and affect icache usage.
522
523	  It is mainly for debug and performance tuning use.
524
525#
526# Select this config option from the architecture Kconfig, if it
527# is preferred to always offer frame pointers as a config
528# option on the architecture (regardless of KERNEL_DEBUG):
529#
530config ARCH_WANT_FRAME_POINTERS
531	bool
532
533config FRAME_POINTER
534	bool "Compile the kernel with frame pointers"
535	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
536	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
537	help
538	  If you say Y here the resulting kernel image will be slightly
539	  larger and slower, but it gives very useful debugging information
540	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
541
542config OBJTOOL
543	bool
544
545config STACK_VALIDATION
546	bool "Compile-time stack metadata validation"
547	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
548	select OBJTOOL
549	default n
550	help
551	  Validate frame pointer rules at compile-time.  This helps ensure that
552	  runtime stack traces are more reliable.
553
554	  For more information, see
555	  tools/objtool/Documentation/objtool.txt.
556
557config NOINSTR_VALIDATION
558	bool
559	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
560	select OBJTOOL
561	default y
562
563config VMLINUX_MAP
564	bool "Generate vmlinux.map file when linking"
565	depends on EXPERT
566	help
567	  Selecting this option will pass "-Map=vmlinux.map" to ld
568	  when linking vmlinux. That file can be useful for verifying
569	  and debugging magic section games, and for seeing which
570	  pieces of code get eliminated with
571	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
572
573config DEBUG_FORCE_WEAK_PER_CPU
574	bool "Force weak per-cpu definitions"
575	depends on DEBUG_KERNEL
576	help
577	  s390 and alpha require percpu variables in modules to be
578	  defined weak to work around addressing range issue which
579	  puts the following two restrictions on percpu variable
580	  definitions.
581
582	  1. percpu symbols must be unique whether static or not
583	  2. percpu variables can't be defined inside a function
584
585	  To ensure that generic code follows the above rules, this
586	  option forces all percpu variables to be defined as weak.
587
588endmenu # "Compiler options"
589
590menu "Generic Kernel Debugging Instruments"
591
592config MAGIC_SYSRQ
593	bool "Magic SysRq key"
594	depends on !UML
595	help
596	  If you say Y here, you will have some control over the system even
597	  if the system crashes for example during kernel debugging (e.g., you
598	  will be able to flush the buffer cache to disk, reboot the system
599	  immediately or dump some status information). This is accomplished
600	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
601	  also works on a serial console (on PC hardware at least), if you
602	  send a BREAK and then within 5 seconds a command keypress. The
603	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
604	  Don't say Y unless you really know what this hack does.
605
606config MAGIC_SYSRQ_DEFAULT_ENABLE
607	hex "Enable magic SysRq key functions by default"
608	depends on MAGIC_SYSRQ
609	default 0x1
610	help
611	  Specifies which SysRq key functions are enabled by default.
612	  This may be set to 1 or 0 to enable or disable them all, or
613	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
614
615config MAGIC_SYSRQ_SERIAL
616	bool "Enable magic SysRq key over serial"
617	depends on MAGIC_SYSRQ
618	default y
619	help
620	  Many embedded boards have a disconnected TTL level serial which can
621	  generate some garbage that can lead to spurious false sysrq detects.
622	  This option allows you to decide whether you want to enable the
623	  magic SysRq key.
624
625config MAGIC_SYSRQ_SERIAL_SEQUENCE
626	string "Char sequence that enables magic SysRq over serial"
627	depends on MAGIC_SYSRQ_SERIAL
628	default ""
629	help
630	  Specifies a sequence of characters that can follow BREAK to enable
631	  SysRq on a serial console.
632
633	  If unsure, leave an empty string and the option will not be enabled.
634
635config DEBUG_FS
636	bool "Debug Filesystem"
637	help
638	  debugfs is a virtual file system that kernel developers use to put
639	  debugging files into.  Enable this option to be able to read and
640	  write to these files.
641
642	  For detailed documentation on the debugfs API, see
643	  Documentation/filesystems/.
644
645	  If unsure, say N.
646
647choice
648	prompt "Debugfs default access"
649	depends on DEBUG_FS
650	default DEBUG_FS_ALLOW_ALL
651	help
652	  This selects the default access restrictions for debugfs.
653	  It can be overridden with kernel command line option
654	  debugfs=[on,no-mount,off]. The restrictions apply for API access
655	  and filesystem registration.
656
657config DEBUG_FS_ALLOW_ALL
658	bool "Access normal"
659	help
660	  No restrictions apply. Both API and filesystem registration
661	  is on. This is the normal default operation.
662
663config DEBUG_FS_DISALLOW_MOUNT
664	bool "Do not register debugfs as filesystem"
665	help
666	  The API is open but filesystem is not loaded. Clients can still do
667	  their work and read with debug tools that do not need
668	  debugfs filesystem.
669
670config DEBUG_FS_ALLOW_NONE
671	bool "No access"
672	help
673	  Access is off. Clients get -PERM when trying to create nodes in
674	  debugfs tree and debugfs is not registered as a filesystem.
675	  Client can then back-off or continue without debugfs access.
676
677endchoice
678
679source "lib/Kconfig.kgdb"
680source "lib/Kconfig.ubsan"
681source "lib/Kconfig.kcsan"
682
683endmenu
684
685menu "Networking Debugging"
686
687source "net/Kconfig.debug"
688
689endmenu # "Networking Debugging"
690
691menu "Memory Debugging"
692
693source "mm/Kconfig.debug"
694
695config DEBUG_OBJECTS
696	bool "Debug object operations"
697	depends on DEBUG_KERNEL
698	help
699	  If you say Y here, additional code will be inserted into the
700	  kernel to track the life time of various objects and validate
701	  the operations on those objects.
702
703config DEBUG_OBJECTS_SELFTEST
704	bool "Debug objects selftest"
705	depends on DEBUG_OBJECTS
706	help
707	  This enables the selftest of the object debug code.
708
709config DEBUG_OBJECTS_FREE
710	bool "Debug objects in freed memory"
711	depends on DEBUG_OBJECTS
712	help
713	  This enables checks whether a k/v free operation frees an area
714	  which contains an object which has not been deactivated
715	  properly. This can make kmalloc/kfree-intensive workloads
716	  much slower.
717
718config DEBUG_OBJECTS_TIMERS
719	bool "Debug timer objects"
720	depends on DEBUG_OBJECTS
721	help
722	  If you say Y here, additional code will be inserted into the
723	  timer routines to track the life time of timer objects and
724	  validate the timer operations.
725
726config DEBUG_OBJECTS_WORK
727	bool "Debug work objects"
728	depends on DEBUG_OBJECTS
729	help
730	  If you say Y here, additional code will be inserted into the
731	  work queue routines to track the life time of work objects and
732	  validate the work operations.
733
734config DEBUG_OBJECTS_RCU_HEAD
735	bool "Debug RCU callbacks objects"
736	depends on DEBUG_OBJECTS
737	help
738	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
739
740config DEBUG_OBJECTS_PERCPU_COUNTER
741	bool "Debug percpu counter objects"
742	depends on DEBUG_OBJECTS
743	help
744	  If you say Y here, additional code will be inserted into the
745	  percpu counter routines to track the life time of percpu counter
746	  objects and validate the percpu counter operations.
747
748config DEBUG_OBJECTS_ENABLE_DEFAULT
749	int "debug_objects bootup default value (0-1)"
750	range 0 1
751	default "1"
752	depends on DEBUG_OBJECTS
753	help
754	  Debug objects boot parameter default value
755
756config SHRINKER_DEBUG
757	bool "Enable shrinker debugging support"
758	depends on DEBUG_FS
759	help
760	  Say Y to enable the shrinker debugfs interface which provides
761	  visibility into the kernel memory shrinkers subsystem.
762	  Disable it to avoid an extra memory footprint.
763
764config DEBUG_STACK_USAGE
765	bool "Stack utilization instrumentation"
766	depends on DEBUG_KERNEL
767	help
768	  Enables the display of the minimum amount of free stack which each
769	  task has ever had available in the sysrq-T and sysrq-P debug output.
770	  Also emits a message to dmesg when a process exits if that process
771	  used more stack space than previously exiting processes.
772
773	  This option will slow down process creation somewhat.
774
775config SCHED_STACK_END_CHECK
776	bool "Detect stack corruption on calls to schedule()"
777	depends on DEBUG_KERNEL
778	default n
779	help
780	  This option checks for a stack overrun on calls to schedule().
781	  If the stack end location is found to be over written always panic as
782	  the content of the corrupted region can no longer be trusted.
783	  This is to ensure no erroneous behaviour occurs which could result in
784	  data corruption or a sporadic crash at a later stage once the region
785	  is examined. The runtime overhead introduced is minimal.
786
787config ARCH_HAS_DEBUG_VM_PGTABLE
788	bool
789	help
790	  An architecture should select this when it can successfully
791	  build and run DEBUG_VM_PGTABLE.
792
793config DEBUG_VM_IRQSOFF
794	def_bool DEBUG_VM && !PREEMPT_RT
795
796config DEBUG_VM
797	bool "Debug VM"
798	depends on DEBUG_KERNEL
799	help
800	  Enable this to turn on extended checks in the virtual-memory system
801	  that may impact performance.
802
803	  If unsure, say N.
804
805config DEBUG_VM_SHOOT_LAZIES
806	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
807	depends on DEBUG_VM
808	depends on MMU_LAZY_TLB_SHOOTDOWN
809	help
810	  Enable additional IPIs that ensure lazy tlb mm references are removed
811	  before the mm is freed.
812
813	  If unsure, say N.
814
815config DEBUG_VM_MAPLE_TREE
816	bool "Debug VM maple trees"
817	depends on DEBUG_VM
818	select DEBUG_MAPLE_TREE
819	help
820	  Enable VM maple tree debugging information and extra validations.
821
822	  If unsure, say N.
823
824config DEBUG_VM_RB
825	bool "Debug VM red-black trees"
826	depends on DEBUG_VM
827	help
828	  Enable VM red-black tree debugging information and extra validations.
829
830	  If unsure, say N.
831
832config DEBUG_VM_PGFLAGS
833	bool "Debug page-flags operations"
834	depends on DEBUG_VM
835	help
836	  Enables extra validation on page flags operations.
837
838	  If unsure, say N.
839
840config DEBUG_VM_PGTABLE
841	bool "Debug arch page table for semantics compliance"
842	depends on MMU
843	depends on ARCH_HAS_DEBUG_VM_PGTABLE
844	default y if DEBUG_VM
845	help
846	  This option provides a debug method which can be used to test
847	  architecture page table helper functions on various platforms in
848	  verifying if they comply with expected generic MM semantics. This
849	  will help architecture code in making sure that any changes or
850	  new additions of these helpers still conform to expected
851	  semantics of the generic MM. Platforms will have to opt in for
852	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
853
854	  If unsure, say N.
855
856config ARCH_HAS_DEBUG_VIRTUAL
857	bool
858
859config DEBUG_VIRTUAL
860	bool "Debug VM translations"
861	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
862	help
863	  Enable some costly sanity checks in virtual to page code. This can
864	  catch mistakes with virt_to_page() and friends.
865
866	  If unsure, say N.
867
868config DEBUG_NOMMU_REGIONS
869	bool "Debug the global anon/private NOMMU mapping region tree"
870	depends on DEBUG_KERNEL && !MMU
871	help
872	  This option causes the global tree of anonymous and private mapping
873	  regions to be regularly checked for invalid topology.
874
875config DEBUG_MEMORY_INIT
876	bool "Debug memory initialisation" if EXPERT
877	default !EXPERT
878	help
879	  Enable this for additional checks during memory initialisation.
880	  The sanity checks verify aspects of the VM such as the memory model
881	  and other information provided by the architecture. Verbose
882	  information will be printed at KERN_DEBUG loglevel depending
883	  on the mminit_loglevel= command-line option.
884
885	  If unsure, say Y
886
887config MEMORY_NOTIFIER_ERROR_INJECT
888	tristate "Memory hotplug notifier error injection module"
889	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
890	help
891	  This option provides the ability to inject artificial errors to
892	  memory hotplug notifier chain callbacks.  It is controlled through
893	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
894
895	  If the notifier call chain should be failed with some events
896	  notified, write the error code to "actions/<notifier event>/error".
897
898	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
899
900	  # cd /sys/kernel/debug/notifier-error-inject/memory
901	  # echo -12 > actions/MEM_GOING_OFFLINE/error
902	  # echo offline > /sys/devices/system/memory/memoryXXX/state
903	  bash: echo: write error: Cannot allocate memory
904
905	  To compile this code as a module, choose M here: the module will
906	  be called memory-notifier-error-inject.
907
908	  If unsure, say N.
909
910config DEBUG_PER_CPU_MAPS
911	bool "Debug access to per_cpu maps"
912	depends on DEBUG_KERNEL
913	depends on SMP
914	help
915	  Say Y to verify that the per_cpu map being accessed has
916	  been set up. This adds a fair amount of code to kernel memory
917	  and decreases performance.
918
919	  Say N if unsure.
920
921config DEBUG_KMAP_LOCAL
922	bool "Debug kmap_local temporary mappings"
923	depends on DEBUG_KERNEL && KMAP_LOCAL
924	help
925	  This option enables additional error checking for the kmap_local
926	  infrastructure.  Disable for production use.
927
928config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
929	bool
930
931config DEBUG_KMAP_LOCAL_FORCE_MAP
932	bool "Enforce kmap_local temporary mappings"
933	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
934	select KMAP_LOCAL
935	select DEBUG_KMAP_LOCAL
936	help
937	  This option enforces temporary mappings through the kmap_local
938	  mechanism for non-highmem pages and on non-highmem systems.
939	  Disable this for production systems!
940
941config DEBUG_HIGHMEM
942	bool "Highmem debugging"
943	depends on DEBUG_KERNEL && HIGHMEM
944	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
945	select DEBUG_KMAP_LOCAL
946	help
947	  This option enables additional error checking for high memory
948	  systems.  Disable for production systems.
949
950config HAVE_DEBUG_STACKOVERFLOW
951	bool
952
953config DEBUG_STACKOVERFLOW
954	bool "Check for stack overflows"
955	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
956	help
957	  Say Y here if you want to check for overflows of kernel, IRQ
958	  and exception stacks (if your architecture uses them). This
959	  option will show detailed messages if free stack space drops
960	  below a certain limit.
961
962	  These kinds of bugs usually occur when call-chains in the
963	  kernel get too deep, especially when interrupts are
964	  involved.
965
966	  Use this in cases where you see apparently random memory
967	  corruption, especially if it appears in 'struct thread_info'
968
969	  If in doubt, say "N".
970
971source "lib/Kconfig.kasan"
972source "lib/Kconfig.kfence"
973source "lib/Kconfig.kmsan"
974
975endmenu # "Memory Debugging"
976
977config DEBUG_SHIRQ
978	bool "Debug shared IRQ handlers"
979	depends on DEBUG_KERNEL
980	help
981	  Enable this to generate a spurious interrupt just before a shared
982	  interrupt handler is deregistered (generating one when registering
983	  is currently disabled). Drivers need to handle this correctly. Some
984	  don't and need to be caught.
985
986menu "Debug Oops, Lockups and Hangs"
987
988config PANIC_ON_OOPS
989	bool "Panic on Oops"
990	help
991	  Say Y here to enable the kernel to panic when it oopses. This
992	  has the same effect as setting oops=panic on the kernel command
993	  line.
994
995	  This feature is useful to ensure that the kernel does not do
996	  anything erroneous after an oops which could result in data
997	  corruption or other issues.
998
999	  Say N if unsure.
1000
1001config PANIC_ON_OOPS_VALUE
1002	int
1003	range 0 1
1004	default 0 if !PANIC_ON_OOPS
1005	default 1 if PANIC_ON_OOPS
1006
1007config PANIC_TIMEOUT
1008	int "panic timeout"
1009	default 0
1010	help
1011	  Set the timeout value (in seconds) until a reboot occurs when
1012	  the kernel panics. If n = 0, then we wait forever. A timeout
1013	  value n > 0 will wait n seconds before rebooting, while a timeout
1014	  value n < 0 will reboot immediately.
1015
1016config LOCKUP_DETECTOR
1017	bool
1018
1019config SOFTLOCKUP_DETECTOR
1020	bool "Detect Soft Lockups"
1021	depends on DEBUG_KERNEL && !S390
1022	select LOCKUP_DETECTOR
1023	help
1024	  Say Y here to enable the kernel to act as a watchdog to detect
1025	  soft lockups.
1026
1027	  Softlockups are bugs that cause the kernel to loop in kernel
1028	  mode for more than 20 seconds, without giving other tasks a
1029	  chance to run.  The current stack trace is displayed upon
1030	  detection and the system will stay locked up.
1031
1032config BOOTPARAM_SOFTLOCKUP_PANIC
1033	bool "Panic (Reboot) On Soft Lockups"
1034	depends on SOFTLOCKUP_DETECTOR
1035	help
1036	  Say Y here to enable the kernel to panic on "soft lockups",
1037	  which are bugs that cause the kernel to loop in kernel
1038	  mode for more than 20 seconds (configurable using the watchdog_thresh
1039	  sysctl), without giving other tasks a chance to run.
1040
1041	  The panic can be used in combination with panic_timeout,
1042	  to cause the system to reboot automatically after a
1043	  lockup has been detected. This feature is useful for
1044	  high-availability systems that have uptime guarantees and
1045	  where a lockup must be resolved ASAP.
1046
1047	  Say N if unsure.
1048
1049config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1050	bool
1051	depends on SMP
1052	default y
1053
1054#
1055# Global switch whether to build a hardlockup detector at all. It is available
1056# only when the architecture supports at least one implementation. There are
1057# two exceptions. The hardlockup detector is never enabled on:
1058#
1059#	s390: it reported many false positives there
1060#
1061#	sparc64: has a custom implementation which is not using the common
1062#		hardlockup command line options and sysctl interface.
1063#
1064config HARDLOCKUP_DETECTOR
1065	bool "Detect Hard Lockups"
1066	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1067	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1068	imply HARDLOCKUP_DETECTOR_PERF
1069	imply HARDLOCKUP_DETECTOR_BUDDY
1070	imply HARDLOCKUP_DETECTOR_ARCH
1071	select LOCKUP_DETECTOR
1072
1073	help
1074	  Say Y here to enable the kernel to act as a watchdog to detect
1075	  hard lockups.
1076
1077	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1078	  for more than 10 seconds, without letting other interrupts have a
1079	  chance to run.  The current stack trace is displayed upon detection
1080	  and the system will stay locked up.
1081
1082#
1083# Note that arch-specific variants are always preferred.
1084#
1085config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1086	bool "Prefer the buddy CPU hardlockup detector"
1087	depends on HARDLOCKUP_DETECTOR
1088	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1089	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1090	help
1091	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1092
1093	  With the buddy detector, each CPU uses its softlockup hrtimer
1094	  to check that the next CPU is processing hrtimer interrupts by
1095	  verifying that a counter is increasing.
1096
1097	  This hardlockup detector is useful on systems that don't have
1098	  an arch-specific hardlockup detector or if resources needed
1099	  for the hardlockup detector are better used for other things.
1100
1101config HARDLOCKUP_DETECTOR_PERF
1102	bool
1103	depends on HARDLOCKUP_DETECTOR
1104	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1105	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1106	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1107
1108config HARDLOCKUP_DETECTOR_BUDDY
1109	bool
1110	depends on HARDLOCKUP_DETECTOR
1111	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1112	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1113	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1114	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1115
1116config HARDLOCKUP_DETECTOR_ARCH
1117	bool
1118	depends on HARDLOCKUP_DETECTOR
1119	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1120	help
1121	  The arch-specific implementation of the hardlockup detector will
1122	  be used.
1123
1124#
1125# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1126# interrupts. This config enables functions managing this common code.
1127#
1128config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1129	bool
1130	select SOFTLOCKUP_DETECTOR
1131
1132#
1133# Enables a timestamp based low pass filter to compensate for perf based
1134# hard lockup detection which runs too fast due to turbo modes.
1135#
1136config HARDLOCKUP_CHECK_TIMESTAMP
1137	bool
1138
1139config BOOTPARAM_HARDLOCKUP_PANIC
1140	bool "Panic (Reboot) On Hard Lockups"
1141	depends on HARDLOCKUP_DETECTOR
1142	help
1143	  Say Y here to enable the kernel to panic on "hard lockups",
1144	  which are bugs that cause the kernel to loop in kernel
1145	  mode with interrupts disabled for more than 10 seconds (configurable
1146	  using the watchdog_thresh sysctl).
1147
1148	  Say N if unsure.
1149
1150config DETECT_HUNG_TASK
1151	bool "Detect Hung Tasks"
1152	depends on DEBUG_KERNEL
1153	default SOFTLOCKUP_DETECTOR
1154	help
1155	  Say Y here to enable the kernel to detect "hung tasks",
1156	  which are bugs that cause the task to be stuck in
1157	  uninterruptible "D" state indefinitely.
1158
1159	  When a hung task is detected, the kernel will print the
1160	  current stack trace (which you should report), but the
1161	  task will stay in uninterruptible state. If lockdep is
1162	  enabled then all held locks will also be reported. This
1163	  feature has negligible overhead.
1164
1165config DEFAULT_HUNG_TASK_TIMEOUT
1166	int "Default timeout for hung task detection (in seconds)"
1167	depends on DETECT_HUNG_TASK
1168	default 120
1169	help
1170	  This option controls the default timeout (in seconds) used
1171	  to determine when a task has become non-responsive and should
1172	  be considered hung.
1173
1174	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1175	  sysctl or by writing a value to
1176	  /proc/sys/kernel/hung_task_timeout_secs.
1177
1178	  A timeout of 0 disables the check.  The default is two minutes.
1179	  Keeping the default should be fine in most cases.
1180
1181config BOOTPARAM_HUNG_TASK_PANIC
1182	bool "Panic (Reboot) On Hung Tasks"
1183	depends on DETECT_HUNG_TASK
1184	help
1185	  Say Y here to enable the kernel to panic on "hung tasks",
1186	  which are bugs that cause the kernel to leave a task stuck
1187	  in uninterruptible "D" state.
1188
1189	  The panic can be used in combination with panic_timeout,
1190	  to cause the system to reboot automatically after a
1191	  hung task has been detected. This feature is useful for
1192	  high-availability systems that have uptime guarantees and
1193	  where a hung tasks must be resolved ASAP.
1194
1195	  Say N if unsure.
1196
1197config WQ_WATCHDOG
1198	bool "Detect Workqueue Stalls"
1199	depends on DEBUG_KERNEL
1200	help
1201	  Say Y here to enable stall detection on workqueues.  If a
1202	  worker pool doesn't make forward progress on a pending work
1203	  item for over a given amount of time, 30s by default, a
1204	  warning message is printed along with dump of workqueue
1205	  state.  This can be configured through kernel parameter
1206	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1207
1208config WQ_CPU_INTENSIVE_REPORT
1209	bool "Report per-cpu work items which hog CPU for too long"
1210	depends on DEBUG_KERNEL
1211	help
1212	  Say Y here to enable reporting of concurrency-managed per-cpu work
1213	  items that hog CPUs for longer than
1214	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1215	  detects and excludes them from concurrency management to prevent
1216	  them from stalling other per-cpu work items. Occassional
1217	  triggering may not necessarily indicate a problem. Repeated
1218	  triggering likely indicates that the work item should be switched
1219	  to use an unbound workqueue.
1220
1221config TEST_LOCKUP
1222	tristate "Test module to generate lockups"
1223	depends on m
1224	help
1225	  This builds the "test_lockup" module that helps to make sure
1226	  that watchdogs and lockup detectors are working properly.
1227
1228	  Depending on module parameters it could emulate soft or hard
1229	  lockup, "hung task", or locking arbitrary lock for a long time.
1230	  Also it could generate series of lockups with cooling-down periods.
1231
1232	  If unsure, say N.
1233
1234endmenu # "Debug lockups and hangs"
1235
1236menu "Scheduler Debugging"
1237
1238config SCHED_DEBUG
1239	bool "Collect scheduler debugging info"
1240	depends on DEBUG_KERNEL && DEBUG_FS
1241	default y
1242	help
1243	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1244	  that can help debug the scheduler. The runtime overhead of this
1245	  option is minimal.
1246
1247config SCHED_INFO
1248	bool
1249	default n
1250
1251config SCHEDSTATS
1252	bool "Collect scheduler statistics"
1253	depends on DEBUG_KERNEL && PROC_FS
1254	select SCHED_INFO
1255	help
1256	  If you say Y here, additional code will be inserted into the
1257	  scheduler and related routines to collect statistics about
1258	  scheduler behavior and provide them in /proc/schedstat.  These
1259	  stats may be useful for both tuning and debugging the scheduler
1260	  If you aren't debugging the scheduler or trying to tune a specific
1261	  application, you can say N to avoid the very slight overhead
1262	  this adds.
1263
1264endmenu
1265
1266config DEBUG_TIMEKEEPING
1267	bool "Enable extra timekeeping sanity checking"
1268	help
1269	  This option will enable additional timekeeping sanity checks
1270	  which may be helpful when diagnosing issues where timekeeping
1271	  problems are suspected.
1272
1273	  This may include checks in the timekeeping hotpaths, so this
1274	  option may have a (very small) performance impact to some
1275	  workloads.
1276
1277	  If unsure, say N.
1278
1279config DEBUG_PREEMPT
1280	bool "Debug preemptible kernel"
1281	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1282	help
1283	  If you say Y here then the kernel will use a debug variant of the
1284	  commonly used smp_processor_id() function and will print warnings
1285	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1286	  will detect preemption count underflows.
1287
1288	  This option has potential to introduce high runtime overhead,
1289	  depending on workload as it triggers debugging routines for each
1290	  this_cpu operation. It should only be used for debugging purposes.
1291
1292menu "Lock Debugging (spinlocks, mutexes, etc...)"
1293
1294config LOCK_DEBUGGING_SUPPORT
1295	bool
1296	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1297	default y
1298
1299config PROVE_LOCKING
1300	bool "Lock debugging: prove locking correctness"
1301	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1302	select LOCKDEP
1303	select DEBUG_SPINLOCK
1304	select DEBUG_MUTEXES if !PREEMPT_RT
1305	select DEBUG_RT_MUTEXES if RT_MUTEXES
1306	select DEBUG_RWSEMS
1307	select DEBUG_WW_MUTEX_SLOWPATH
1308	select DEBUG_LOCK_ALLOC
1309	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1310	select TRACE_IRQFLAGS
1311	default n
1312	help
1313	 This feature enables the kernel to prove that all locking
1314	 that occurs in the kernel runtime is mathematically
1315	 correct: that under no circumstance could an arbitrary (and
1316	 not yet triggered) combination of observed locking
1317	 sequences (on an arbitrary number of CPUs, running an
1318	 arbitrary number of tasks and interrupt contexts) cause a
1319	 deadlock.
1320
1321	 In short, this feature enables the kernel to report locking
1322	 related deadlocks before they actually occur.
1323
1324	 The proof does not depend on how hard and complex a
1325	 deadlock scenario would be to trigger: how many
1326	 participant CPUs, tasks and irq-contexts would be needed
1327	 for it to trigger. The proof also does not depend on
1328	 timing: if a race and a resulting deadlock is possible
1329	 theoretically (no matter how unlikely the race scenario
1330	 is), it will be proven so and will immediately be
1331	 reported by the kernel (once the event is observed that
1332	 makes the deadlock theoretically possible).
1333
1334	 If a deadlock is impossible (i.e. the locking rules, as
1335	 observed by the kernel, are mathematically correct), the
1336	 kernel reports nothing.
1337
1338	 NOTE: this feature can also be enabled for rwlocks, mutexes
1339	 and rwsems - in which case all dependencies between these
1340	 different locking variants are observed and mapped too, and
1341	 the proof of observed correctness is also maintained for an
1342	 arbitrary combination of these separate locking variants.
1343
1344	 For more details, see Documentation/locking/lockdep-design.rst.
1345
1346config PROVE_RAW_LOCK_NESTING
1347	bool "Enable raw_spinlock - spinlock nesting checks"
1348	depends on PROVE_LOCKING
1349	default n
1350	help
1351	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1352	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1353	 not violated.
1354
1355	 NOTE: There are known nesting problems. So if you enable this
1356	 option expect lockdep splats until these problems have been fully
1357	 addressed which is work in progress. This config switch allows to
1358	 identify and analyze these problems. It will be removed and the
1359	 check permanently enabled once the main issues have been fixed.
1360
1361	 If unsure, select N.
1362
1363config LOCK_STAT
1364	bool "Lock usage statistics"
1365	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1366	select LOCKDEP
1367	select DEBUG_SPINLOCK
1368	select DEBUG_MUTEXES if !PREEMPT_RT
1369	select DEBUG_RT_MUTEXES if RT_MUTEXES
1370	select DEBUG_LOCK_ALLOC
1371	default n
1372	help
1373	 This feature enables tracking lock contention points
1374
1375	 For more details, see Documentation/locking/lockstat.rst
1376
1377	 This also enables lock events required by "perf lock",
1378	 subcommand of perf.
1379	 If you want to use "perf lock", you also need to turn on
1380	 CONFIG_EVENT_TRACING.
1381
1382	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1383	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1384
1385config DEBUG_RT_MUTEXES
1386	bool "RT Mutex debugging, deadlock detection"
1387	depends on DEBUG_KERNEL && RT_MUTEXES
1388	help
1389	 This allows rt mutex semantics violations and rt mutex related
1390	 deadlocks (lockups) to be detected and reported automatically.
1391
1392config DEBUG_SPINLOCK
1393	bool "Spinlock and rw-lock debugging: basic checks"
1394	depends on DEBUG_KERNEL
1395	select UNINLINE_SPIN_UNLOCK
1396	help
1397	  Say Y here and build SMP to catch missing spinlock initialization
1398	  and certain other kinds of spinlock errors commonly made.  This is
1399	  best used in conjunction with the NMI watchdog so that spinlock
1400	  deadlocks are also debuggable.
1401
1402config DEBUG_MUTEXES
1403	bool "Mutex debugging: basic checks"
1404	depends on DEBUG_KERNEL && !PREEMPT_RT
1405	help
1406	 This feature allows mutex semantics violations to be detected and
1407	 reported.
1408
1409config DEBUG_WW_MUTEX_SLOWPATH
1410	bool "Wait/wound mutex debugging: Slowpath testing"
1411	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1412	select DEBUG_LOCK_ALLOC
1413	select DEBUG_SPINLOCK
1414	select DEBUG_MUTEXES if !PREEMPT_RT
1415	select DEBUG_RT_MUTEXES if PREEMPT_RT
1416	help
1417	 This feature enables slowpath testing for w/w mutex users by
1418	 injecting additional -EDEADLK wound/backoff cases. Together with
1419	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1420	 will test all possible w/w mutex interface abuse with the
1421	 exception of simply not acquiring all the required locks.
1422	 Note that this feature can introduce significant overhead, so
1423	 it really should not be enabled in a production or distro kernel,
1424	 even a debug kernel.  If you are a driver writer, enable it.  If
1425	 you are a distro, do not.
1426
1427config DEBUG_RWSEMS
1428	bool "RW Semaphore debugging: basic checks"
1429	depends on DEBUG_KERNEL
1430	help
1431	  This debugging feature allows mismatched rw semaphore locks
1432	  and unlocks to be detected and reported.
1433
1434config DEBUG_LOCK_ALLOC
1435	bool "Lock debugging: detect incorrect freeing of live locks"
1436	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1437	select DEBUG_SPINLOCK
1438	select DEBUG_MUTEXES if !PREEMPT_RT
1439	select DEBUG_RT_MUTEXES if RT_MUTEXES
1440	select LOCKDEP
1441	help
1442	 This feature will check whether any held lock (spinlock, rwlock,
1443	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1444	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1445	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1446	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1447	 held during task exit.
1448
1449config LOCKDEP
1450	bool
1451	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1452	select STACKTRACE
1453	select KALLSYMS
1454	select KALLSYMS_ALL
1455
1456config LOCKDEP_SMALL
1457	bool
1458
1459config LOCKDEP_BITS
1460	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1461	depends on LOCKDEP && !LOCKDEP_SMALL
1462	range 10 30
1463	default 15
1464	help
1465	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1466
1467config LOCKDEP_CHAINS_BITS
1468	int "Bitsize for MAX_LOCKDEP_CHAINS"
1469	depends on LOCKDEP && !LOCKDEP_SMALL
1470	range 10 30
1471	default 16
1472	help
1473	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1474
1475config LOCKDEP_STACK_TRACE_BITS
1476	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1477	depends on LOCKDEP && !LOCKDEP_SMALL
1478	range 10 30
1479	default 19
1480	help
1481	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1482
1483config LOCKDEP_STACK_TRACE_HASH_BITS
1484	int "Bitsize for STACK_TRACE_HASH_SIZE"
1485	depends on LOCKDEP && !LOCKDEP_SMALL
1486	range 10 30
1487	default 14
1488	help
1489	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1490
1491config LOCKDEP_CIRCULAR_QUEUE_BITS
1492	int "Bitsize for elements in circular_queue struct"
1493	depends on LOCKDEP
1494	range 10 30
1495	default 12
1496	help
1497	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1498
1499config DEBUG_LOCKDEP
1500	bool "Lock dependency engine debugging"
1501	depends on DEBUG_KERNEL && LOCKDEP
1502	select DEBUG_IRQFLAGS
1503	help
1504	  If you say Y here, the lock dependency engine will do
1505	  additional runtime checks to debug itself, at the price
1506	  of more runtime overhead.
1507
1508config DEBUG_ATOMIC_SLEEP
1509	bool "Sleep inside atomic section checking"
1510	select PREEMPT_COUNT
1511	depends on DEBUG_KERNEL
1512	depends on !ARCH_NO_PREEMPT
1513	help
1514	  If you say Y here, various routines which may sleep will become very
1515	  noisy if they are called inside atomic sections: when a spinlock is
1516	  held, inside an rcu read side critical section, inside preempt disabled
1517	  sections, inside an interrupt, etc...
1518
1519config DEBUG_LOCKING_API_SELFTESTS
1520	bool "Locking API boot-time self-tests"
1521	depends on DEBUG_KERNEL
1522	help
1523	  Say Y here if you want the kernel to run a short self-test during
1524	  bootup. The self-test checks whether common types of locking bugs
1525	  are detected by debugging mechanisms or not. (if you disable
1526	  lock debugging then those bugs won't be detected of course.)
1527	  The following locking APIs are covered: spinlocks, rwlocks,
1528	  mutexes and rwsems.
1529
1530config LOCK_TORTURE_TEST
1531	tristate "torture tests for locking"
1532	depends on DEBUG_KERNEL
1533	select TORTURE_TEST
1534	help
1535	  This option provides a kernel module that runs torture tests
1536	  on kernel locking primitives.  The kernel module may be built
1537	  after the fact on the running kernel to be tested, if desired.
1538
1539	  Say Y here if you want kernel locking-primitive torture tests
1540	  to be built into the kernel.
1541	  Say M if you want these torture tests to build as a module.
1542	  Say N if you are unsure.
1543
1544config WW_MUTEX_SELFTEST
1545	tristate "Wait/wound mutex selftests"
1546	help
1547	  This option provides a kernel module that runs tests on the
1548	  on the struct ww_mutex locking API.
1549
1550	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1551	  with this test harness.
1552
1553	  Say M if you want these self tests to build as a module.
1554	  Say N if you are unsure.
1555
1556config SCF_TORTURE_TEST
1557	tristate "torture tests for smp_call_function*()"
1558	depends on DEBUG_KERNEL
1559	select TORTURE_TEST
1560	help
1561	  This option provides a kernel module that runs torture tests
1562	  on the smp_call_function() family of primitives.  The kernel
1563	  module may be built after the fact on the running kernel to
1564	  be tested, if desired.
1565
1566config CSD_LOCK_WAIT_DEBUG
1567	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1568	depends on DEBUG_KERNEL
1569	depends on 64BIT
1570	default n
1571	help
1572	  This option enables debug prints when CPUs are slow to respond
1573	  to the smp_call_function*() IPI wrappers.  These debug prints
1574	  include the IPI handler function currently executing (if any)
1575	  and relevant stack traces.
1576
1577config CSD_LOCK_WAIT_DEBUG_DEFAULT
1578	bool "Default csd_lock_wait() debugging on at boot time"
1579	depends on CSD_LOCK_WAIT_DEBUG
1580	depends on 64BIT
1581	default n
1582	help
1583	  This option causes the csdlock_debug= kernel boot parameter to
1584	  default to 1 (basic debugging) instead of 0 (no debugging).
1585
1586endmenu # lock debugging
1587
1588config TRACE_IRQFLAGS
1589	depends on TRACE_IRQFLAGS_SUPPORT
1590	bool
1591	help
1592	  Enables hooks to interrupt enabling and disabling for
1593	  either tracing or lock debugging.
1594
1595config TRACE_IRQFLAGS_NMI
1596	def_bool y
1597	depends on TRACE_IRQFLAGS
1598	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1599
1600config NMI_CHECK_CPU
1601	bool "Debugging for CPUs failing to respond to backtrace requests"
1602	depends on DEBUG_KERNEL
1603	depends on X86
1604	default n
1605	help
1606	  Enables debug prints when a CPU fails to respond to a given
1607	  backtrace NMI.  These prints provide some reasons why a CPU
1608	  might legitimately be failing to respond, for example, if it
1609	  is offline of if ignore_nmis is set.
1610
1611config DEBUG_IRQFLAGS
1612	bool "Debug IRQ flag manipulation"
1613	help
1614	  Enables checks for potentially unsafe enabling or disabling of
1615	  interrupts, such as calling raw_local_irq_restore() when interrupts
1616	  are enabled.
1617
1618config STACKTRACE
1619	bool "Stack backtrace support"
1620	depends on STACKTRACE_SUPPORT
1621	help
1622	  This option causes the kernel to create a /proc/pid/stack for
1623	  every process, showing its current stack trace.
1624	  It is also used by various kernel debugging features that require
1625	  stack trace generation.
1626
1627config WARN_ALL_UNSEEDED_RANDOM
1628	bool "Warn for all uses of unseeded randomness"
1629	default n
1630	help
1631	  Some parts of the kernel contain bugs relating to their use of
1632	  cryptographically secure random numbers before it's actually possible
1633	  to generate those numbers securely. This setting ensures that these
1634	  flaws don't go unnoticed, by enabling a message, should this ever
1635	  occur. This will allow people with obscure setups to know when things
1636	  are going wrong, so that they might contact developers about fixing
1637	  it.
1638
1639	  Unfortunately, on some models of some architectures getting
1640	  a fully seeded CRNG is extremely difficult, and so this can
1641	  result in dmesg getting spammed for a surprisingly long
1642	  time.  This is really bad from a security perspective, and
1643	  so architecture maintainers really need to do what they can
1644	  to get the CRNG seeded sooner after the system is booted.
1645	  However, since users cannot do anything actionable to
1646	  address this, by default this option is disabled.
1647
1648	  Say Y here if you want to receive warnings for all uses of
1649	  unseeded randomness.  This will be of use primarily for
1650	  those developers interested in improving the security of
1651	  Linux kernels running on their architecture (or
1652	  subarchitecture).
1653
1654config DEBUG_KOBJECT
1655	bool "kobject debugging"
1656	depends on DEBUG_KERNEL
1657	help
1658	  If you say Y here, some extra kobject debugging messages will be sent
1659	  to the syslog.
1660
1661config DEBUG_KOBJECT_RELEASE
1662	bool "kobject release debugging"
1663	depends on DEBUG_OBJECTS_TIMERS
1664	help
1665	  kobjects are reference counted objects.  This means that their
1666	  last reference count put is not predictable, and the kobject can
1667	  live on past the point at which a driver decides to drop its
1668	  initial reference to the kobject gained on allocation.  An
1669	  example of this would be a struct device which has just been
1670	  unregistered.
1671
1672	  However, some buggy drivers assume that after such an operation,
1673	  the memory backing the kobject can be immediately freed.  This
1674	  goes completely against the principles of a refcounted object.
1675
1676	  If you say Y here, the kernel will delay the release of kobjects
1677	  on the last reference count to improve the visibility of this
1678	  kind of kobject release bug.
1679
1680config HAVE_DEBUG_BUGVERBOSE
1681	bool
1682
1683menu "Debug kernel data structures"
1684
1685config DEBUG_LIST
1686	bool "Debug linked list manipulation"
1687	depends on DEBUG_KERNEL
1688	select LIST_HARDENED
1689	help
1690	  Enable this to turn on extended checks in the linked-list walking
1691	  routines.
1692
1693	  This option trades better quality error reports for performance, and
1694	  is more suitable for kernel debugging. If you care about performance,
1695	  you should only enable CONFIG_LIST_HARDENED instead.
1696
1697	  If unsure, say N.
1698
1699config DEBUG_PLIST
1700	bool "Debug priority linked list manipulation"
1701	depends on DEBUG_KERNEL
1702	help
1703	  Enable this to turn on extended checks in the priority-ordered
1704	  linked-list (plist) walking routines.  This checks the entire
1705	  list multiple times during each manipulation.
1706
1707	  If unsure, say N.
1708
1709config DEBUG_SG
1710	bool "Debug SG table operations"
1711	depends on DEBUG_KERNEL
1712	help
1713	  Enable this to turn on checks on scatter-gather tables. This can
1714	  help find problems with drivers that do not properly initialize
1715	  their sg tables.
1716
1717	  If unsure, say N.
1718
1719config DEBUG_NOTIFIERS
1720	bool "Debug notifier call chains"
1721	depends on DEBUG_KERNEL
1722	help
1723	  Enable this to turn on sanity checking for notifier call chains.
1724	  This is most useful for kernel developers to make sure that
1725	  modules properly unregister themselves from notifier chains.
1726	  This is a relatively cheap check but if you care about maximum
1727	  performance, say N.
1728
1729config DEBUG_CLOSURES
1730	bool "Debug closures (bcache async widgits)"
1731	depends on CLOSURES
1732	select DEBUG_FS
1733	help
1734	  Keeps all active closures in a linked list and provides a debugfs
1735	  interface to list them, which makes it possible to see asynchronous
1736	  operations that get stuck.
1737
1738config DEBUG_MAPLE_TREE
1739	bool "Debug maple trees"
1740	depends on DEBUG_KERNEL
1741	help
1742	  Enable maple tree debugging information and extra validations.
1743
1744	  If unsure, say N.
1745
1746endmenu
1747
1748source "kernel/rcu/Kconfig.debug"
1749
1750config DEBUG_WQ_FORCE_RR_CPU
1751	bool "Force round-robin CPU selection for unbound work items"
1752	depends on DEBUG_KERNEL
1753	default n
1754	help
1755	  Workqueue used to implicitly guarantee that work items queued
1756	  without explicit CPU specified are put on the local CPU.  This
1757	  guarantee is no longer true and while local CPU is still
1758	  preferred work items may be put on foreign CPUs.  Kernel
1759	  parameter "workqueue.debug_force_rr_cpu" is added to force
1760	  round-robin CPU selection to flush out usages which depend on the
1761	  now broken guarantee.  This config option enables the debug
1762	  feature by default.  When enabled, memory and cache locality will
1763	  be impacted.
1764
1765config CPU_HOTPLUG_STATE_CONTROL
1766	bool "Enable CPU hotplug state control"
1767	depends on DEBUG_KERNEL
1768	depends on HOTPLUG_CPU
1769	default n
1770	help
1771	  Allows to write steps between "offline" and "online" to the CPUs
1772	  sysfs target file so states can be stepped granular. This is a debug
1773	  option for now as the hotplug machinery cannot be stopped and
1774	  restarted at arbitrary points yet.
1775
1776	  Say N if your are unsure.
1777
1778config LATENCYTOP
1779	bool "Latency measuring infrastructure"
1780	depends on DEBUG_KERNEL
1781	depends on STACKTRACE_SUPPORT
1782	depends on PROC_FS
1783	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1784	select KALLSYMS
1785	select KALLSYMS_ALL
1786	select STACKTRACE
1787	select SCHEDSTATS
1788	help
1789	  Enable this option if you want to use the LatencyTOP tool
1790	  to find out which userspace is blocking on what kernel operations.
1791
1792config DEBUG_CGROUP_REF
1793	bool "Disable inlining of cgroup css reference count functions"
1794	depends on DEBUG_KERNEL
1795	depends on CGROUPS
1796	depends on KPROBES
1797	default n
1798	help
1799	  Force cgroup css reference count functions to not be inlined so
1800	  that they can be kprobed for debugging.
1801
1802source "kernel/trace/Kconfig"
1803
1804config PROVIDE_OHCI1394_DMA_INIT
1805	bool "Remote debugging over FireWire early on boot"
1806	depends on PCI && X86
1807	help
1808	  If you want to debug problems which hang or crash the kernel early
1809	  on boot and the crashing machine has a FireWire port, you can use
1810	  this feature to remotely access the memory of the crashed machine
1811	  over FireWire. This employs remote DMA as part of the OHCI1394
1812	  specification which is now the standard for FireWire controllers.
1813
1814	  With remote DMA, you can monitor the printk buffer remotely using
1815	  firescope and access all memory below 4GB using fireproxy from gdb.
1816	  Even controlling a kernel debugger is possible using remote DMA.
1817
1818	  Usage:
1819
1820	  If ohci1394_dma=early is used as boot parameter, it will initialize
1821	  all OHCI1394 controllers which are found in the PCI config space.
1822
1823	  As all changes to the FireWire bus such as enabling and disabling
1824	  devices cause a bus reset and thereby disable remote DMA for all
1825	  devices, be sure to have the cable plugged and FireWire enabled on
1826	  the debugging host before booting the debug target for debugging.
1827
1828	  This code (~1k) is freed after boot. By then, the firewire stack
1829	  in charge of the OHCI-1394 controllers should be used instead.
1830
1831	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1832
1833source "samples/Kconfig"
1834
1835config ARCH_HAS_DEVMEM_IS_ALLOWED
1836	bool
1837
1838config STRICT_DEVMEM
1839	bool "Filter access to /dev/mem"
1840	depends on MMU && DEVMEM
1841	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1842	default y if PPC || X86 || ARM64
1843	help
1844	  If this option is disabled, you allow userspace (root) access to all
1845	  of memory, including kernel and userspace memory. Accidental
1846	  access to this is obviously disastrous, but specific access can
1847	  be used by people debugging the kernel. Note that with PAT support
1848	  enabled, even in this case there are restrictions on /dev/mem
1849	  use due to the cache aliasing requirements.
1850
1851	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1852	  file only allows userspace access to PCI space and the BIOS code and
1853	  data regions.  This is sufficient for dosemu and X and all common
1854	  users of /dev/mem.
1855
1856	  If in doubt, say Y.
1857
1858config IO_STRICT_DEVMEM
1859	bool "Filter I/O access to /dev/mem"
1860	depends on STRICT_DEVMEM
1861	help
1862	  If this option is disabled, you allow userspace (root) access to all
1863	  io-memory regardless of whether a driver is actively using that
1864	  range.  Accidental access to this is obviously disastrous, but
1865	  specific access can be used by people debugging kernel drivers.
1866
1867	  If this option is switched on, the /dev/mem file only allows
1868	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1869	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1870	  if the driver using a given range cannot be disabled.
1871
1872	  If in doubt, say Y.
1873
1874menu "$(SRCARCH) Debugging"
1875
1876source "arch/$(SRCARCH)/Kconfig.debug"
1877
1878endmenu
1879
1880menu "Kernel Testing and Coverage"
1881
1882source "lib/kunit/Kconfig"
1883
1884config NOTIFIER_ERROR_INJECTION
1885	tristate "Notifier error injection"
1886	depends on DEBUG_KERNEL
1887	select DEBUG_FS
1888	help
1889	  This option provides the ability to inject artificial errors to
1890	  specified notifier chain callbacks. It is useful to test the error
1891	  handling of notifier call chain failures.
1892
1893	  Say N if unsure.
1894
1895config PM_NOTIFIER_ERROR_INJECT
1896	tristate "PM notifier error injection module"
1897	depends on PM && NOTIFIER_ERROR_INJECTION
1898	default m if PM_DEBUG
1899	help
1900	  This option provides the ability to inject artificial errors to
1901	  PM notifier chain callbacks.  It is controlled through debugfs
1902	  interface /sys/kernel/debug/notifier-error-inject/pm
1903
1904	  If the notifier call chain should be failed with some events
1905	  notified, write the error code to "actions/<notifier event>/error".
1906
1907	  Example: Inject PM suspend error (-12 = -ENOMEM)
1908
1909	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1910	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1911	  # echo mem > /sys/power/state
1912	  bash: echo: write error: Cannot allocate memory
1913
1914	  To compile this code as a module, choose M here: the module will
1915	  be called pm-notifier-error-inject.
1916
1917	  If unsure, say N.
1918
1919config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1920	tristate "OF reconfig notifier error injection module"
1921	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1922	help
1923	  This option provides the ability to inject artificial errors to
1924	  OF reconfig notifier chain callbacks.  It is controlled
1925	  through debugfs interface under
1926	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1927
1928	  If the notifier call chain should be failed with some events
1929	  notified, write the error code to "actions/<notifier event>/error".
1930
1931	  To compile this code as a module, choose M here: the module will
1932	  be called of-reconfig-notifier-error-inject.
1933
1934	  If unsure, say N.
1935
1936config NETDEV_NOTIFIER_ERROR_INJECT
1937	tristate "Netdev notifier error injection module"
1938	depends on NET && NOTIFIER_ERROR_INJECTION
1939	help
1940	  This option provides the ability to inject artificial errors to
1941	  netdevice notifier chain callbacks.  It is controlled through debugfs
1942	  interface /sys/kernel/debug/notifier-error-inject/netdev
1943
1944	  If the notifier call chain should be failed with some events
1945	  notified, write the error code to "actions/<notifier event>/error".
1946
1947	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1948
1949	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1950	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1951	  # ip link set eth0 mtu 1024
1952	  RTNETLINK answers: Invalid argument
1953
1954	  To compile this code as a module, choose M here: the module will
1955	  be called netdev-notifier-error-inject.
1956
1957	  If unsure, say N.
1958
1959config FUNCTION_ERROR_INJECTION
1960	bool "Fault-injections of functions"
1961	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1962	help
1963	  Add fault injections into various functions that are annotated with
1964	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1965	  value of these functions. This is useful to test error paths of code.
1966
1967	  If unsure, say N
1968
1969config FAULT_INJECTION
1970	bool "Fault-injection framework"
1971	depends on DEBUG_KERNEL
1972	help
1973	  Provide fault-injection framework.
1974	  For more details, see Documentation/fault-injection/.
1975
1976config FAILSLAB
1977	bool "Fault-injection capability for kmalloc"
1978	depends on FAULT_INJECTION
1979	help
1980	  Provide fault-injection capability for kmalloc.
1981
1982config FAIL_PAGE_ALLOC
1983	bool "Fault-injection capability for alloc_pages()"
1984	depends on FAULT_INJECTION
1985	help
1986	  Provide fault-injection capability for alloc_pages().
1987
1988config FAULT_INJECTION_USERCOPY
1989	bool "Fault injection capability for usercopy functions"
1990	depends on FAULT_INJECTION
1991	help
1992	  Provides fault-injection capability to inject failures
1993	  in usercopy functions (copy_from_user(), get_user(), ...).
1994
1995config FAIL_MAKE_REQUEST
1996	bool "Fault-injection capability for disk IO"
1997	depends on FAULT_INJECTION && BLOCK
1998	help
1999	  Provide fault-injection capability for disk IO.
2000
2001config FAIL_IO_TIMEOUT
2002	bool "Fault-injection capability for faking disk interrupts"
2003	depends on FAULT_INJECTION && BLOCK
2004	help
2005	  Provide fault-injection capability on end IO handling. This
2006	  will make the block layer "forget" an interrupt as configured,
2007	  thus exercising the error handling.
2008
2009	  Only works with drivers that use the generic timeout handling,
2010	  for others it won't do anything.
2011
2012config FAIL_FUTEX
2013	bool "Fault-injection capability for futexes"
2014	select DEBUG_FS
2015	depends on FAULT_INJECTION && FUTEX
2016	help
2017	  Provide fault-injection capability for futexes.
2018
2019config FAULT_INJECTION_DEBUG_FS
2020	bool "Debugfs entries for fault-injection capabilities"
2021	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2022	help
2023	  Enable configuration of fault-injection capabilities via debugfs.
2024
2025config FAIL_FUNCTION
2026	bool "Fault-injection capability for functions"
2027	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2028	help
2029	  Provide function-based fault-injection capability.
2030	  This will allow you to override a specific function with a return
2031	  with given return value. As a result, function caller will see
2032	  an error value and have to handle it. This is useful to test the
2033	  error handling in various subsystems.
2034
2035config FAIL_MMC_REQUEST
2036	bool "Fault-injection capability for MMC IO"
2037	depends on FAULT_INJECTION_DEBUG_FS && MMC
2038	help
2039	  Provide fault-injection capability for MMC IO.
2040	  This will make the mmc core return data errors. This is
2041	  useful to test the error handling in the mmc block device
2042	  and to test how the mmc host driver handles retries from
2043	  the block device.
2044
2045config FAIL_SUNRPC
2046	bool "Fault-injection capability for SunRPC"
2047	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2048	help
2049	  Provide fault-injection capability for SunRPC and
2050	  its consumers.
2051
2052config FAULT_INJECTION_CONFIGFS
2053	bool "Configfs interface for fault-injection capabilities"
2054	depends on FAULT_INJECTION
2055	select CONFIGFS_FS
2056	help
2057	  This option allows configfs-based drivers to dynamically configure
2058	  fault-injection via configfs.  Each parameter for driver-specific
2059	  fault-injection can be made visible as a configfs attribute in a
2060	  configfs group.
2061
2062
2063config FAULT_INJECTION_STACKTRACE_FILTER
2064	bool "stacktrace filter for fault-injection capabilities"
2065	depends on FAULT_INJECTION
2066	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2067	select STACKTRACE
2068	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2069	help
2070	  Provide stacktrace filter for fault-injection capabilities
2071
2072config ARCH_HAS_KCOV
2073	bool
2074	help
2075	  An architecture should select this when it can successfully
2076	  build and run with CONFIG_KCOV. This typically requires
2077	  disabling instrumentation for some early boot code.
2078
2079config CC_HAS_SANCOV_TRACE_PC
2080	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2081
2082
2083config KCOV
2084	bool "Code coverage for fuzzing"
2085	depends on ARCH_HAS_KCOV
2086	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2087	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2088		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2089	select DEBUG_FS
2090	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2091	select OBJTOOL if HAVE_NOINSTR_HACK
2092	help
2093	  KCOV exposes kernel code coverage information in a form suitable
2094	  for coverage-guided fuzzing (randomized testing).
2095
2096	  For more details, see Documentation/dev-tools/kcov.rst.
2097
2098config KCOV_ENABLE_COMPARISONS
2099	bool "Enable comparison operands collection by KCOV"
2100	depends on KCOV
2101	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2102	help
2103	  KCOV also exposes operands of every comparison in the instrumented
2104	  code along with operand sizes and PCs of the comparison instructions.
2105	  These operands can be used by fuzzing engines to improve the quality
2106	  of fuzzing coverage.
2107
2108config KCOV_INSTRUMENT_ALL
2109	bool "Instrument all code by default"
2110	depends on KCOV
2111	default y
2112	help
2113	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2114	  then you will want to instrument the whole kernel and you should
2115	  say y here. If you are doing more targeted fuzzing (like e.g.
2116	  filesystem fuzzing with AFL) then you will want to enable coverage
2117	  for more specific subsets of files, and should say n here.
2118
2119config KCOV_IRQ_AREA_SIZE
2120	hex "Size of interrupt coverage collection area in words"
2121	depends on KCOV
2122	default 0x40000
2123	help
2124	  KCOV uses preallocated per-cpu areas to collect coverage from
2125	  soft interrupts. This specifies the size of those areas in the
2126	  number of unsigned long words.
2127
2128menuconfig RUNTIME_TESTING_MENU
2129	bool "Runtime Testing"
2130	def_bool y
2131
2132if RUNTIME_TESTING_MENU
2133
2134config TEST_DHRY
2135	tristate "Dhrystone benchmark test"
2136	help
2137	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2138	  calculates the number of Dhrystones per second, and the number of
2139	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2140	  by 1757 (the number of Dhrystones per second obtained on the VAX
2141	  11/780, nominally a 1 MIPS machine).
2142
2143	  To run the benchmark, it needs to be enabled explicitly, either from
2144	  the kernel command line (when built-in), or from userspace (when
2145	  built-in or modular.
2146
2147	  Run once during kernel boot:
2148
2149	      test_dhry.run
2150
2151	  Set number of iterations from kernel command line:
2152
2153	      test_dhry.iterations=<n>
2154
2155	  Set number of iterations from userspace:
2156
2157	      echo <n> > /sys/module/test_dhry/parameters/iterations
2158
2159	  Trigger manual run from userspace:
2160
2161	      echo y > /sys/module/test_dhry/parameters/run
2162
2163	  If the number of iterations is <= 0, the test will devise a suitable
2164	  number of iterations (test runs for at least 2s) automatically.
2165	  This process takes ca. 4s.
2166
2167	  If unsure, say N.
2168
2169config LKDTM
2170	tristate "Linux Kernel Dump Test Tool Module"
2171	depends on DEBUG_FS
2172	help
2173	This module enables testing of the different dumping mechanisms by
2174	inducing system failures at predefined crash points.
2175	If you don't need it: say N
2176	Choose M here to compile this code as a module. The module will be
2177	called lkdtm.
2178
2179	Documentation on how to use the module can be found in
2180	Documentation/fault-injection/provoke-crashes.rst
2181
2182config CPUMASK_KUNIT_TEST
2183	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2184	depends on KUNIT
2185	default KUNIT_ALL_TESTS
2186	help
2187	  Enable to turn on cpumask tests, running at boot or module load time.
2188
2189	  For more information on KUnit and unit tests in general, please refer
2190	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2191
2192	  If unsure, say N.
2193
2194config TEST_LIST_SORT
2195	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2196	depends on KUNIT
2197	default KUNIT_ALL_TESTS
2198	help
2199	  Enable this to turn on 'list_sort()' function test. This test is
2200	  executed only once during system boot (so affects only boot time),
2201	  or at module load time.
2202
2203	  If unsure, say N.
2204
2205config TEST_MIN_HEAP
2206	tristate "Min heap test"
2207	depends on DEBUG_KERNEL || m
2208	help
2209	  Enable this to turn on min heap function tests. This test is
2210	  executed only once during system boot (so affects only boot time),
2211	  or at module load time.
2212
2213	  If unsure, say N.
2214
2215config TEST_SORT
2216	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2217	depends on KUNIT
2218	default KUNIT_ALL_TESTS
2219	help
2220	  This option enables the self-test function of 'sort()' at boot,
2221	  or at module load time.
2222
2223	  If unsure, say N.
2224
2225config TEST_DIV64
2226	tristate "64bit/32bit division and modulo test"
2227	depends on DEBUG_KERNEL || m
2228	help
2229	  Enable this to turn on 'do_div()' function test. This test is
2230	  executed only once during system boot (so affects only boot time),
2231	  or at module load time.
2232
2233	  If unsure, say N.
2234
2235config TEST_IOV_ITER
2236	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2237	depends on KUNIT
2238	depends on MMU
2239	default KUNIT_ALL_TESTS
2240	help
2241	  Enable this to turn on testing of the operation of the I/O iterator
2242	  (iov_iter). This test is executed only once during system boot (so
2243	  affects only boot time), or at module load time.
2244
2245	  If unsure, say N.
2246
2247config KPROBES_SANITY_TEST
2248	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2249	depends on DEBUG_KERNEL
2250	depends on KPROBES
2251	depends on KUNIT
2252	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2253	default KUNIT_ALL_TESTS
2254	help
2255	  This option provides for testing basic kprobes functionality on
2256	  boot. Samples of kprobe and kretprobe are inserted and
2257	  verified for functionality.
2258
2259	  Say N if you are unsure.
2260
2261config FPROBE_SANITY_TEST
2262	bool "Self test for fprobe"
2263	depends on DEBUG_KERNEL
2264	depends on FPROBE
2265	depends on KUNIT=y
2266	help
2267	  This option will enable testing the fprobe when the system boot.
2268	  A series of tests are made to verify that the fprobe is functioning
2269	  properly.
2270
2271	  Say N if you are unsure.
2272
2273config BACKTRACE_SELF_TEST
2274	tristate "Self test for the backtrace code"
2275	depends on DEBUG_KERNEL
2276	help
2277	  This option provides a kernel module that can be used to test
2278	  the kernel stack backtrace code. This option is not useful
2279	  for distributions or general kernels, but only for kernel
2280	  developers working on architecture code.
2281
2282	  Note that if you want to also test saved backtraces, you will
2283	  have to enable STACKTRACE as well.
2284
2285	  Say N if you are unsure.
2286
2287config TEST_REF_TRACKER
2288	tristate "Self test for reference tracker"
2289	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2290	select REF_TRACKER
2291	help
2292	  This option provides a kernel module performing tests
2293	  using reference tracker infrastructure.
2294
2295	  Say N if you are unsure.
2296
2297config RBTREE_TEST
2298	tristate "Red-Black tree test"
2299	depends on DEBUG_KERNEL
2300	help
2301	  A benchmark measuring the performance of the rbtree library.
2302	  Also includes rbtree invariant checks.
2303
2304config REED_SOLOMON_TEST
2305	tristate "Reed-Solomon library test"
2306	depends on DEBUG_KERNEL || m
2307	select REED_SOLOMON
2308	select REED_SOLOMON_ENC16
2309	select REED_SOLOMON_DEC16
2310	help
2311	  This option enables the self-test function of rslib at boot,
2312	  or at module load time.
2313
2314	  If unsure, say N.
2315
2316config INTERVAL_TREE_TEST
2317	tristate "Interval tree test"
2318	depends on DEBUG_KERNEL
2319	select INTERVAL_TREE
2320	help
2321	  A benchmark measuring the performance of the interval tree library
2322
2323config PERCPU_TEST
2324	tristate "Per cpu operations test"
2325	depends on m && DEBUG_KERNEL
2326	help
2327	  Enable this option to build test module which validates per-cpu
2328	  operations.
2329
2330	  If unsure, say N.
2331
2332config ATOMIC64_SELFTEST
2333	tristate "Perform an atomic64_t self-test"
2334	help
2335	  Enable this option to test the atomic64_t functions at boot or
2336	  at module load time.
2337
2338	  If unsure, say N.
2339
2340config ASYNC_RAID6_TEST
2341	tristate "Self test for hardware accelerated raid6 recovery"
2342	depends on ASYNC_RAID6_RECOV
2343	select ASYNC_MEMCPY
2344	help
2345	  This is a one-shot self test that permutes through the
2346	  recovery of all the possible two disk failure scenarios for a
2347	  N-disk array.  Recovery is performed with the asynchronous
2348	  raid6 recovery routines, and will optionally use an offload
2349	  engine if one is available.
2350
2351	  If unsure, say N.
2352
2353config TEST_HEXDUMP
2354	tristate "Test functions located in the hexdump module at runtime"
2355
2356config STRING_SELFTEST
2357	tristate "Test string functions at runtime"
2358
2359config TEST_STRING_HELPERS
2360	tristate "Test functions located in the string_helpers module at runtime"
2361
2362config TEST_KSTRTOX
2363	tristate "Test kstrto*() family of functions at runtime"
2364
2365config TEST_PRINTF
2366	tristate "Test printf() family of functions at runtime"
2367
2368config TEST_SCANF
2369	tristate "Test scanf() family of functions at runtime"
2370
2371config TEST_BITMAP
2372	tristate "Test bitmap_*() family of functions at runtime"
2373	help
2374	  Enable this option to test the bitmap functions at boot.
2375
2376	  If unsure, say N.
2377
2378config TEST_UUID
2379	tristate "Test functions located in the uuid module at runtime"
2380
2381config TEST_XARRAY
2382	tristate "Test the XArray code at runtime"
2383
2384config TEST_MAPLE_TREE
2385	tristate "Test the Maple Tree code at runtime or module load"
2386	help
2387	  Enable this option to test the maple tree code functions at boot, or
2388	  when the module is loaded. Enable "Debug Maple Trees" will enable
2389	  more verbose output on failures.
2390
2391	  If unsure, say N.
2392
2393config TEST_RHASHTABLE
2394	tristate "Perform selftest on resizable hash table"
2395	help
2396	  Enable this option to test the rhashtable functions at boot.
2397
2398	  If unsure, say N.
2399
2400config TEST_IDA
2401	tristate "Perform selftest on IDA functions"
2402
2403config TEST_PARMAN
2404	tristate "Perform selftest on priority array manager"
2405	depends on PARMAN
2406	help
2407	  Enable this option to test priority array manager on boot
2408	  (or module load).
2409
2410	  If unsure, say N.
2411
2412config TEST_IRQ_TIMINGS
2413	bool "IRQ timings selftest"
2414	depends on IRQ_TIMINGS
2415	help
2416	  Enable this option to test the irq timings code on boot.
2417
2418	  If unsure, say N.
2419
2420config TEST_LKM
2421	tristate "Test module loading with 'hello world' module"
2422	depends on m
2423	help
2424	  This builds the "test_module" module that emits "Hello, world"
2425	  on printk when loaded. It is designed to be used for basic
2426	  evaluation of the module loading subsystem (for example when
2427	  validating module verification). It lacks any extra dependencies,
2428	  and will not normally be loaded by the system unless explicitly
2429	  requested by name.
2430
2431	  If unsure, say N.
2432
2433config TEST_BITOPS
2434	tristate "Test module for compilation of bitops operations"
2435	depends on m
2436	help
2437	  This builds the "test_bitops" module that is much like the
2438	  TEST_LKM module except that it does a basic exercise of the
2439	  set/clear_bit macros and get_count_order/long to make sure there are
2440	  no compiler warnings from C=1 sparse checker or -Wextra
2441	  compilations. It has no dependencies and doesn't run or load unless
2442	  explicitly requested by name.  for example: modprobe test_bitops.
2443
2444	  If unsure, say N.
2445
2446config TEST_VMALLOC
2447	tristate "Test module for stress/performance analysis of vmalloc allocator"
2448	default n
2449       depends on MMU
2450	depends on m
2451	help
2452	  This builds the "test_vmalloc" module that should be used for
2453	  stress and performance analysis. So, any new change for vmalloc
2454	  subsystem can be evaluated from performance and stability point
2455	  of view.
2456
2457	  If unsure, say N.
2458
2459config TEST_USER_COPY
2460	tristate "Test user/kernel boundary protections"
2461	depends on m
2462	help
2463	  This builds the "test_user_copy" module that runs sanity checks
2464	  on the copy_to/from_user infrastructure, making sure basic
2465	  user/kernel boundary testing is working. If it fails to load,
2466	  a regression has been detected in the user/kernel memory boundary
2467	  protections.
2468
2469	  If unsure, say N.
2470
2471config TEST_BPF
2472	tristate "Test BPF filter functionality"
2473	depends on m && NET
2474	help
2475	  This builds the "test_bpf" module that runs various test vectors
2476	  against the BPF interpreter or BPF JIT compiler depending on the
2477	  current setting. This is in particular useful for BPF JIT compiler
2478	  development, but also to run regression tests against changes in
2479	  the interpreter code. It also enables test stubs for eBPF maps and
2480	  verifier used by user space verifier testsuite.
2481
2482	  If unsure, say N.
2483
2484config TEST_BLACKHOLE_DEV
2485	tristate "Test blackhole netdev functionality"
2486	depends on m && NET
2487	help
2488	  This builds the "test_blackhole_dev" module that validates the
2489	  data path through this blackhole netdev.
2490
2491	  If unsure, say N.
2492
2493config FIND_BIT_BENCHMARK
2494	tristate "Test find_bit functions"
2495	help
2496	  This builds the "test_find_bit" module that measure find_*_bit()
2497	  functions performance.
2498
2499	  If unsure, say N.
2500
2501config TEST_FIRMWARE
2502	tristate "Test firmware loading via userspace interface"
2503	depends on FW_LOADER
2504	help
2505	  This builds the "test_firmware" module that creates a userspace
2506	  interface for testing firmware loading. This can be used to
2507	  control the triggering of firmware loading without needing an
2508	  actual firmware-using device. The contents can be rechecked by
2509	  userspace.
2510
2511	  If unsure, say N.
2512
2513config TEST_SYSCTL
2514	tristate "sysctl test driver"
2515	depends on PROC_SYSCTL
2516	help
2517	  This builds the "test_sysctl" module. This driver enables to test the
2518	  proc sysctl interfaces available to drivers safely without affecting
2519	  production knobs which might alter system functionality.
2520
2521	  If unsure, say N.
2522
2523config BITFIELD_KUNIT
2524	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2525	depends on KUNIT
2526	default KUNIT_ALL_TESTS
2527	help
2528	  Enable this option to test the bitfield functions at boot.
2529
2530	  KUnit tests run during boot and output the results to the debug log
2531	  in TAP format (http://testanything.org/). Only useful for kernel devs
2532	  running the KUnit test harness, and not intended for inclusion into a
2533	  production build.
2534
2535	  For more information on KUnit and unit tests in general please refer
2536	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2537
2538	  If unsure, say N.
2539
2540config CHECKSUM_KUNIT
2541	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2542	depends on KUNIT
2543	default KUNIT_ALL_TESTS
2544	help
2545	  Enable this option to test the checksum functions at boot.
2546
2547	  KUnit tests run during boot and output the results to the debug log
2548	  in TAP format (http://testanything.org/). Only useful for kernel devs
2549	  running the KUnit test harness, and not intended for inclusion into a
2550	  production build.
2551
2552	  For more information on KUnit and unit tests in general please refer
2553	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2554
2555	  If unsure, say N.
2556
2557config HASH_KUNIT_TEST
2558	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2559	depends on KUNIT
2560	default KUNIT_ALL_TESTS
2561	help
2562	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2563	  integer (<linux/hash.h>) hash functions on boot.
2564
2565	  KUnit tests run during boot and output the results to the debug log
2566	  in TAP format (https://testanything.org/). Only useful for kernel devs
2567	  running the KUnit test harness, and not intended for inclusion into a
2568	  production build.
2569
2570	  For more information on KUnit and unit tests in general please refer
2571	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2572
2573	  This is intended to help people writing architecture-specific
2574	  optimized versions. If unsure, say N.
2575
2576config RESOURCE_KUNIT_TEST
2577	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2578	depends on KUNIT
2579	default KUNIT_ALL_TESTS
2580	help
2581	  This builds the resource API unit test.
2582	  Tests the logic of API provided by resource.c and ioport.h.
2583	  For more information on KUnit and unit tests in general please refer
2584	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2585
2586	  If unsure, say N.
2587
2588config SYSCTL_KUNIT_TEST
2589	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2590	depends on KUNIT
2591	default KUNIT_ALL_TESTS
2592	help
2593	  This builds the proc sysctl unit test, which runs on boot.
2594	  Tests the API contract and implementation correctness of sysctl.
2595	  For more information on KUnit and unit tests in general please refer
2596	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2597
2598	  If unsure, say N.
2599
2600config LIST_KUNIT_TEST
2601	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2602	depends on KUNIT
2603	default KUNIT_ALL_TESTS
2604	help
2605	  This builds the linked list KUnit test suite.
2606	  It tests that the API and basic functionality of the list_head type
2607	  and associated macros.
2608
2609	  KUnit tests run during boot and output the results to the debug log
2610	  in TAP format (https://testanything.org/). Only useful for kernel devs
2611	  running the KUnit test harness, and not intended for inclusion into a
2612	  production build.
2613
2614	  For more information on KUnit and unit tests in general please refer
2615	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2616
2617	  If unsure, say N.
2618
2619config HASHTABLE_KUNIT_TEST
2620	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2621	depends on KUNIT
2622	default KUNIT_ALL_TESTS
2623	help
2624	  This builds the hashtable KUnit test suite.
2625	  It tests the basic functionality of the API defined in
2626	  include/linux/hashtable.h. For more information on KUnit and
2627	  unit tests in general please refer to the KUnit documentation
2628	  in Documentation/dev-tools/kunit/.
2629
2630	  If unsure, say N.
2631
2632config LINEAR_RANGES_TEST
2633	tristate "KUnit test for linear_ranges"
2634	depends on KUNIT
2635	select LINEAR_RANGES
2636	help
2637	  This builds the linear_ranges unit test, which runs on boot.
2638	  Tests the linear_ranges logic correctness.
2639	  For more information on KUnit and unit tests in general please refer
2640	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2641
2642	  If unsure, say N.
2643
2644config CMDLINE_KUNIT_TEST
2645	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2646	depends on KUNIT
2647	default KUNIT_ALL_TESTS
2648	help
2649	  This builds the cmdline API unit test.
2650	  Tests the logic of API provided by cmdline.c.
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 BITS_TEST
2657	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2658	depends on KUNIT
2659	default KUNIT_ALL_TESTS
2660	help
2661	  This builds the bits unit test.
2662	  Tests the logic of macros defined in bits.h.
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 SLUB_KUNIT_TEST
2669	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2670	depends on SLUB_DEBUG && KUNIT
2671	default KUNIT_ALL_TESTS
2672	help
2673	  This builds SLUB allocator unit test.
2674	  Tests SLUB cache debugging functionality.
2675	  For more information on KUnit and unit tests in general please refer
2676	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2677
2678	  If unsure, say N.
2679
2680config RATIONAL_KUNIT_TEST
2681	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2682	depends on KUNIT && RATIONAL
2683	default KUNIT_ALL_TESTS
2684	help
2685	  This builds the rational math unit test.
2686	  For more information on KUnit and unit tests in general please refer
2687	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2688
2689	  If unsure, say N.
2690
2691config MEMCPY_KUNIT_TEST
2692	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2693	depends on KUNIT
2694	default KUNIT_ALL_TESTS
2695	help
2696	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2697	  For more information on KUnit and unit tests in general please refer
2698	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2699
2700	  If unsure, say N.
2701
2702config MEMCPY_SLOW_KUNIT_TEST
2703	bool "Include exhaustive memcpy tests"
2704	depends on MEMCPY_KUNIT_TEST
2705	default y
2706	help
2707	  Some memcpy tests are quite exhaustive in checking for overlaps
2708	  and bit ranges. These can be very slow, so they are split out
2709	  as a separate config, in case they need to be disabled.
2710
2711	  Note this config option will be replaced by the use of KUnit test
2712	  attributes.
2713
2714config IS_SIGNED_TYPE_KUNIT_TEST
2715	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2716	depends on KUNIT
2717	default KUNIT_ALL_TESTS
2718	help
2719	  Builds unit tests for the is_signed_type() macro.
2720
2721	  For more information on KUnit and unit tests in general please refer
2722	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2723
2724	  If unsure, say N.
2725
2726config OVERFLOW_KUNIT_TEST
2727	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2728	depends on KUNIT
2729	default KUNIT_ALL_TESTS
2730	help
2731	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2732	  related functions.
2733
2734	  For more information on KUnit and unit tests in general please refer
2735	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2736
2737	  If unsure, say N.
2738
2739config STACKINIT_KUNIT_TEST
2740	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2741	depends on KUNIT
2742	default KUNIT_ALL_TESTS
2743	help
2744	  Test if the kernel is zero-initializing stack variables and
2745	  padding. Coverage is controlled by compiler flags,
2746	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2747	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2748	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2749
2750config FORTIFY_KUNIT_TEST
2751	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2752	depends on KUNIT && FORTIFY_SOURCE
2753	default KUNIT_ALL_TESTS
2754	help
2755	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2756	  by the str*() and mem*() family of functions. For testing runtime
2757	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2758
2759config HW_BREAKPOINT_KUNIT_TEST
2760	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2761	depends on HAVE_HW_BREAKPOINT
2762	depends on KUNIT=y
2763	default KUNIT_ALL_TESTS
2764	help
2765	  Tests for hw_breakpoint constraints accounting.
2766
2767	  If unsure, say N.
2768
2769config STRCAT_KUNIT_TEST
2770	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2771	depends on KUNIT
2772	default KUNIT_ALL_TESTS
2773
2774config STRSCPY_KUNIT_TEST
2775	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2776	depends on KUNIT
2777	default KUNIT_ALL_TESTS
2778
2779config SIPHASH_KUNIT_TEST
2780	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2781	depends on KUNIT
2782	default KUNIT_ALL_TESTS
2783	help
2784	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2785	  functions on boot (or module load).
2786
2787	  This is intended to help people writing architecture-specific
2788	  optimized versions.  If unsure, say N.
2789
2790config TEST_UDELAY
2791	tristate "udelay test driver"
2792	help
2793	  This builds the "udelay_test" module that helps to make sure
2794	  that udelay() is working properly.
2795
2796	  If unsure, say N.
2797
2798config TEST_STATIC_KEYS
2799	tristate "Test static keys"
2800	depends on m
2801	help
2802	  Test the static key interfaces.
2803
2804	  If unsure, say N.
2805
2806config TEST_DYNAMIC_DEBUG
2807	tristate "Test DYNAMIC_DEBUG"
2808	depends on DYNAMIC_DEBUG
2809	help
2810	  This module registers a tracer callback to count enabled
2811	  pr_debugs in a 'do_debugging' function, then alters their
2812	  enablements, calls the function, and compares counts.
2813
2814	  If unsure, say N.
2815
2816config TEST_KMOD
2817	tristate "kmod stress tester"
2818	depends on m
2819	depends on NETDEVICES && NET_CORE && INET # for TUN
2820	depends on BLOCK
2821	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2822	select TEST_LKM
2823	select XFS_FS
2824	select TUN
2825	select BTRFS_FS
2826	help
2827	  Test the kernel's module loading mechanism: kmod. kmod implements
2828	  support to load modules using the Linux kernel's usermode helper.
2829	  This test provides a series of tests against kmod.
2830
2831	  Although technically you can either build test_kmod as a module or
2832	  into the kernel we disallow building it into the kernel since
2833	  it stress tests request_module() and this will very likely cause
2834	  some issues by taking over precious threads available from other
2835	  module load requests, ultimately this could be fatal.
2836
2837	  To run tests run:
2838
2839	  tools/testing/selftests/kmod/kmod.sh --help
2840
2841	  If unsure, say N.
2842
2843config TEST_DEBUG_VIRTUAL
2844	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2845	depends on DEBUG_VIRTUAL
2846	help
2847	  Test the kernel's ability to detect incorrect calls to
2848	  virt_to_phys() done against the non-linear part of the
2849	  kernel's virtual address map.
2850
2851	  If unsure, say N.
2852
2853config TEST_MEMCAT_P
2854	tristate "Test memcat_p() helper function"
2855	help
2856	  Test the memcat_p() helper for correctly merging two
2857	  pointer arrays together.
2858
2859	  If unsure, say N.
2860
2861config TEST_LIVEPATCH
2862	tristate "Test livepatching"
2863	default n
2864	depends on DYNAMIC_DEBUG
2865	depends on LIVEPATCH
2866	depends on m
2867	help
2868	  Test kernel livepatching features for correctness.  The tests will
2869	  load test modules that will be livepatched in various scenarios.
2870
2871	  To run all the livepatching tests:
2872
2873	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2874
2875	  Alternatively, individual tests may be invoked:
2876
2877	  tools/testing/selftests/livepatch/test-callbacks.sh
2878	  tools/testing/selftests/livepatch/test-livepatch.sh
2879	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2880
2881	  If unsure, say N.
2882
2883config TEST_OBJAGG
2884	tristate "Perform selftest on object aggreration manager"
2885	default n
2886	depends on OBJAGG
2887	help
2888	  Enable this option to test object aggregation manager on boot
2889	  (or module load).
2890
2891config TEST_MEMINIT
2892	tristate "Test heap/page initialization"
2893	help
2894	  Test if the kernel is zero-initializing heap and page allocations.
2895	  This can be useful to test init_on_alloc and init_on_free features.
2896
2897	  If unsure, say N.
2898
2899config TEST_HMM
2900	tristate "Test HMM (Heterogeneous Memory Management)"
2901	depends on TRANSPARENT_HUGEPAGE
2902	depends on DEVICE_PRIVATE
2903	select HMM_MIRROR
2904	select MMU_NOTIFIER
2905	help
2906	  This is a pseudo device driver solely for testing HMM.
2907	  Say M here if you want to build the HMM test module.
2908	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2909
2910	  If unsure, say N.
2911
2912config TEST_FREE_PAGES
2913	tristate "Test freeing pages"
2914	help
2915	  Test that a memory leak does not occur due to a race between
2916	  freeing a block of pages and a speculative page reference.
2917	  Loading this module is safe if your kernel has the bug fixed.
2918	  If the bug is not fixed, it will leak gigabytes of memory and
2919	  probably OOM your system.
2920
2921config TEST_FPU
2922	tristate "Test floating point operations in kernel space"
2923	depends on X86 && !KCOV_INSTRUMENT_ALL
2924	help
2925	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2926	  which will trigger a sequence of floating point operations. This is used
2927	  for self-testing floating point control register setting in
2928	  kernel_fpu_begin().
2929
2930	  If unsure, say N.
2931
2932config TEST_CLOCKSOURCE_WATCHDOG
2933	tristate "Test clocksource watchdog in kernel space"
2934	depends on CLOCKSOURCE_WATCHDOG
2935	help
2936	  Enable this option to create a kernel module that will trigger
2937	  a test of the clocksource watchdog.  This module may be loaded
2938	  via modprobe or insmod in which case it will run upon being
2939	  loaded, or it may be built in, in which case it will run
2940	  shortly after boot.
2941
2942	  If unsure, say N.
2943
2944config TEST_OBJPOOL
2945	tristate "Test module for correctness and stress of objpool"
2946	default n
2947	depends on m && DEBUG_KERNEL
2948	help
2949	  This builds the "test_objpool" module that should be used for
2950	  correctness verification and concurrent testings of objects
2951	  allocation and reclamation.
2952
2953	  If unsure, say N.
2954
2955endif # RUNTIME_TESTING_MENU
2956
2957config ARCH_USE_MEMTEST
2958	bool
2959	help
2960	  An architecture should select this when it uses early_memtest()
2961	  during boot process.
2962
2963config MEMTEST
2964	bool "Memtest"
2965	depends on ARCH_USE_MEMTEST
2966	help
2967	  This option adds a kernel parameter 'memtest', which allows memtest
2968	  to be set and executed.
2969	        memtest=0, mean disabled; -- default
2970	        memtest=1, mean do 1 test pattern;
2971	        ...
2972	        memtest=17, mean do 17 test patterns.
2973	  If you are unsure how to answer this question, answer N.
2974
2975
2976
2977config HYPERV_TESTING
2978	bool "Microsoft Hyper-V driver testing"
2979	default n
2980	depends on HYPERV && DEBUG_FS
2981	help
2982	  Select this option to enable Hyper-V vmbus testing.
2983
2984endmenu # "Kernel Testing and Coverage"
2985
2986menu "Rust hacking"
2987
2988config RUST_DEBUG_ASSERTIONS
2989	bool "Debug assertions"
2990	depends on RUST
2991	help
2992	  Enables rustc's `-Cdebug-assertions` codegen option.
2993
2994	  This flag lets you turn `cfg(debug_assertions)` conditional
2995	  compilation on or off. This can be used to enable extra debugging
2996	  code in development but not in production. For example, it controls
2997	  the behavior of the standard library's `debug_assert!` macro.
2998
2999	  Note that this will apply to all Rust code, including `core`.
3000
3001	  If unsure, say N.
3002
3003config RUST_OVERFLOW_CHECKS
3004	bool "Overflow checks"
3005	default y
3006	depends on RUST
3007	help
3008	  Enables rustc's `-Coverflow-checks` codegen option.
3009
3010	  This flag allows you to control the behavior of runtime integer
3011	  overflow. When overflow-checks are enabled, a Rust panic will occur
3012	  on overflow.
3013
3014	  Note that this will apply to all Rust code, including `core`.
3015
3016	  If unsure, say Y.
3017
3018config RUST_BUILD_ASSERT_ALLOW
3019	bool "Allow unoptimized build-time assertions"
3020	depends on RUST
3021	help
3022	  Controls how are `build_error!` and `build_assert!` handled during build.
3023
3024	  If calls to them exist in the binary, it may indicate a violated invariant
3025	  or that the optimizer failed to verify the invariant during compilation.
3026
3027	  This should not happen, thus by default the build is aborted. However,
3028	  as an escape hatch, you can choose Y here to ignore them during build
3029	  and let the check be carried at runtime (with `panic!` being called if
3030	  the check fails).
3031
3032	  If unsure, say N.
3033
3034config RUST_KERNEL_DOCTESTS
3035	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3036	depends on RUST && KUNIT=y
3037	default KUNIT_ALL_TESTS
3038	help
3039	  This builds the documentation tests of the `kernel` crate
3040	  as KUnit tests.
3041
3042	  For more information on KUnit and unit tests in general,
3043	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3044
3045	  If unsure, say N.
3046
3047endmenu # "Rust"
3048
3049endmenu # Kernel hacking
3050