xref: /linux/lib/Kconfig.debug (revision ae84ff9a)
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 is known to generate .{s,u}leb128 with symbol deltas with DWARF5, which
235# some targets may not support: https://sourceware.org/bugzilla/show_bug.cgi?id=27215
236config AS_HAS_NON_CONST_LEB128
237	def_bool $(as-instr,.uleb128 .Lexpr_end4 - .Lexpr_start3\n.Lexpr_start3:\n.Lexpr_end4:)
238
239choice
240	prompt "Debug information"
241	depends on DEBUG_KERNEL
242	help
243	  Selecting something other than "None" results in a kernel image
244	  that will include debugging info resulting in a larger kernel image.
245	  This adds debug symbols to the kernel and modules (gcc -g), and
246	  is needed if you intend to use kernel crashdump or binary object
247	  tools like crash, kgdb, LKCD, gdb, etc on the kernel.
248
249	  Choose which version of DWARF debug info to emit. If unsure,
250	  select "Toolchain default".
251
252config DEBUG_INFO_NONE
253	bool "Disable debug information"
254	help
255	  Do not build the kernel with debugging information, which will
256	  result in a faster and smaller build.
257
258config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
259	bool "Rely on the toolchain's implicit default DWARF version"
260	select DEBUG_INFO
261	depends on !CC_IS_CLANG || AS_IS_LLVM || CLANG_VERSION < 140000 || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
262	help
263	  The implicit default version of DWARF debug info produced by a
264	  toolchain changes over time.
265
266	  This can break consumers of the debug info that haven't upgraded to
267	  support newer revisions, and prevent testing newer versions, but
268	  those should be less common scenarios.
269
270config DEBUG_INFO_DWARF4
271	bool "Generate DWARF Version 4 debuginfo"
272	select DEBUG_INFO
273	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)
274	help
275	  Generate DWARF v4 debug info. This requires gcc 4.5+, binutils 2.35.2
276	  if using clang without clang's integrated assembler, and gdb 7.0+.
277
278	  If you have consumers of DWARF debug info that are not ready for
279	  newer revisions of DWARF, you may wish to choose this or have your
280	  config select this.
281
282config DEBUG_INFO_DWARF5
283	bool "Generate DWARF Version 5 debuginfo"
284	select DEBUG_INFO
285	depends on !ARCH_HAS_BROKEN_DWARF5
286	depends on !CC_IS_CLANG || AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502 && AS_HAS_NON_CONST_LEB128)
287	help
288	  Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc
289	  5.0+ accepts the -gdwarf-5 flag but only had partial support for some
290	  draft features until 7.0), and gdb 8.0+.
291
292	  Changes to the structure of debug info in Version 5 allow for around
293	  15-18% savings in resulting image and debug info section sizes as
294	  compared to DWARF Version 4. DWARF Version 5 standardizes previous
295	  extensions such as accelerators for symbol indexing and the format
296	  for fission (.dwo/.dwp) files. Users may not want to select this
297	  config if they rely on tooling that has not yet been updated to
298	  support DWARF Version 5.
299
300endchoice # "Debug information"
301
302if DEBUG_INFO
303
304config DEBUG_INFO_REDUCED
305	bool "Reduce debugging information"
306	help
307	  If you say Y here gcc is instructed to generate less debugging
308	  information for structure types. This means that tools that
309	  need full debugging information (like kgdb or systemtap) won't
310	  be happy. But if you merely need debugging information to
311	  resolve line numbers there is no loss. Advantage is that
312	  build directory object sizes shrink dramatically over a full
313	  DEBUG_INFO build and compile times are reduced too.
314	  Only works with newer gcc versions.
315
316choice
317	prompt "Compressed Debug information"
318	help
319	  Compress the resulting debug info. Results in smaller debug info sections,
320	  but requires that consumers are able to decompress the results.
321
322	  If unsure, choose DEBUG_INFO_COMPRESSED_NONE.
323
324config DEBUG_INFO_COMPRESSED_NONE
325	bool "Don't compress debug information"
326	help
327	  Don't compress debug info sections.
328
329config DEBUG_INFO_COMPRESSED_ZLIB
330	bool "Compress debugging information with zlib"
331	depends on $(cc-option,-gz=zlib)
332	depends on $(ld-option,--compress-debug-sections=zlib)
333	help
334	  Compress the debug information using zlib.  Requires GCC 5.0+ or Clang
335	  5.0+, binutils 2.26+, and zlib.
336
337	  Users of dpkg-deb via scripts/package/builddeb may find an increase in
338	  size of their debug .deb packages with this config set, due to the
339	  debug info being compressed with zlib, then the object files being
340	  recompressed with a different compression scheme. But this is still
341	  preferable to setting $KDEB_COMPRESS to "none" which would be even
342	  larger.
343
344config DEBUG_INFO_COMPRESSED_ZSTD
345	bool "Compress debugging information with zstd"
346	depends on $(cc-option,-gz=zstd)
347	depends on $(ld-option,--compress-debug-sections=zstd)
348	help
349	  Compress the debug information using zstd.  This may provide better
350	  compression than zlib, for about the same time costs, but requires newer
351	  toolchain support.  Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and
352	  zstd.
353
354endchoice # "Compressed Debug information"
355
356config DEBUG_INFO_SPLIT
357	bool "Produce split debuginfo in .dwo files"
358	depends on $(cc-option,-gsplit-dwarf)
359	# RISC-V linker relaxation + -gsplit-dwarf has issues with LLVM and GCC
360	# prior to 12.x:
361	# https://github.com/llvm/llvm-project/issues/56642
362	# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
363	depends on !RISCV || GCC_VERSION >= 120000
364	help
365	  Generate debug info into separate .dwo files. This significantly
366	  reduces the build directory size for builds with DEBUG_INFO,
367	  because it stores the information only once on disk in .dwo
368	  files instead of multiple times in object files and executables.
369	  In addition the debug information is also compressed.
370
371	  Requires recent gcc (4.7+) and recent gdb/binutils.
372	  Any tool that packages or reads debug information would need
373	  to know about the .dwo files and include them.
374	  Incompatible with older versions of ccache.
375
376config DEBUG_INFO_BTF
377	bool "Generate BTF typeinfo"
378	depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
379	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
380	depends on BPF_SYSCALL
381	depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
382	help
383	  Generate deduplicated BTF type information from DWARF debug info.
384	  Turning this on expects presence of pahole tool, which will convert
385	  DWARF type info into equivalent deduplicated BTF type info.
386
387config PAHOLE_HAS_SPLIT_BTF
388	def_bool PAHOLE_VERSION >= 119
389
390config PAHOLE_HAS_BTF_TAG
391	def_bool PAHOLE_VERSION >= 123
392	depends on CC_IS_CLANG
393	help
394	  Decide whether pahole emits btf_tag attributes (btf_type_tag and
395	  btf_decl_tag) or not. Currently only clang compiler implements
396	  these attributes, so make the config depend on CC_IS_CLANG.
397
398config PAHOLE_HAS_LANG_EXCLUDE
399	def_bool PAHOLE_VERSION >= 124
400	help
401	  Support for the --lang_exclude flag which makes pahole exclude
402	  compilation units from the supplied language. Used in Kbuild to
403	  omit Rust CUs which are not supported in version 1.24 of pahole,
404	  otherwise it would emit malformed kernel and module binaries when
405	  using DEBUG_INFO_BTF_MODULES.
406
407config DEBUG_INFO_BTF_MODULES
408	def_bool y
409	depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF
410	help
411	  Generate compact split BTF type information for kernel modules.
412
413config MODULE_ALLOW_BTF_MISMATCH
414	bool "Allow loading modules with non-matching BTF type info"
415	depends on DEBUG_INFO_BTF_MODULES
416	help
417	  For modules whose split BTF does not match vmlinux, load without
418	  BTF rather than refusing to load. The default behavior with
419	  module BTF enabled is to reject modules with such mismatches;
420	  this option will still load module BTF where possible but ignore
421	  it when a mismatch is found.
422
423config GDB_SCRIPTS
424	bool "Provide GDB scripts for kernel debugging"
425	help
426	  This creates the required links to GDB helper scripts in the
427	  build directory. If you load vmlinux into gdb, the helper
428	  scripts will be automatically imported by gdb as well, and
429	  additional functions are available to analyze a Linux kernel
430	  instance. See Documentation/dev-tools/gdb-kernel-debugging.rst
431	  for further details.
432
433endif # DEBUG_INFO
434
435config FRAME_WARN
436	int "Warn for stack frames larger than"
437	range 0 8192
438	default 0 if KMSAN
439	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
440	default 2048 if PARISC
441	default 1536 if (!64BIT && XTENSA)
442	default 1280 if KASAN && !64BIT
443	default 1024 if !64BIT
444	default 2048 if 64BIT
445	help
446	  Tell the compiler to warn at build time for stack frames larger than this.
447	  Setting this too low will cause a lot of warnings.
448	  Setting it to 0 disables the warning.
449
450config STRIP_ASM_SYMS
451	bool "Strip assembler-generated symbols during link"
452	default n
453	help
454	  Strip internal assembler-generated symbols during a link (symbols
455	  that look like '.Lxxx') so they don't pollute the output of
456	  get_wchan() and suchlike.
457
458config READABLE_ASM
459	bool "Generate readable assembler code"
460	depends on DEBUG_KERNEL
461	depends on CC_IS_GCC
462	help
463	  Disable some compiler optimizations that tend to generate human unreadable
464	  assembler output. This may make the kernel slightly slower, but it helps
465	  to keep kernel developers who have to stare a lot at assembler listings
466	  sane.
467
468config HEADERS_INSTALL
469	bool "Install uapi headers to usr/include"
470	depends on !UML
471	help
472	  This option will install uapi headers (headers exported to user-space)
473	  into the usr/include directory for use during the kernel build.
474	  This is unneeded for building the kernel itself, but needed for some
475	  user-space program samples. It is also needed by some features such
476	  as uapi header sanity checks.
477
478config DEBUG_SECTION_MISMATCH
479	bool "Enable full Section mismatch analysis"
480	depends on CC_IS_GCC
481	help
482	  The section mismatch analysis checks if there are illegal
483	  references from one section to another section.
484	  During linktime or runtime, some sections are dropped;
485	  any use of code/data previously in these sections would
486	  most likely result in an oops.
487	  In the code, functions and variables are annotated with
488	  __init,, etc. (see the full list in include/linux/init.h),
489	  which results in the code/data being placed in specific sections.
490	  The section mismatch analysis is always performed after a full
491	  kernel build, and enabling this option causes the following
492	  additional step to occur:
493	  - Add the option -fno-inline-functions-called-once to gcc commands.
494	    When inlining a function annotated with __init in a non-init
495	    function, we would lose the section information and thus
496	    the analysis would not catch the illegal reference.
497	    This option tells gcc to inline less (but it does result in
498	    a larger kernel).
499
500config SECTION_MISMATCH_WARN_ONLY
501	bool "Make section mismatch errors non-fatal"
502	default y
503	help
504	  If you say N here, the build process will fail if there are any
505	  section mismatch, instead of just throwing warnings.
506
507	  If unsure, say Y.
508
509config DEBUG_FORCE_FUNCTION_ALIGN_64B
510	bool "Force all function address 64B aligned"
511	depends on EXPERT && (X86_64 || ARM64 || PPC32 || PPC64 || ARC || RISCV || S390)
512	select FUNCTION_ALIGNMENT_64B
513	help
514	  There are cases that a commit from one domain changes the function
515	  address alignment of other domains, and cause magic performance
516	  bump (regression or improvement). Enable this option will help to
517	  verify if the bump is caused by function alignment changes, while
518	  it will slightly increase the kernel size and affect icache usage.
519
520	  It is mainly for debug and performance tuning use.
521
522#
523# Select this config option from the architecture Kconfig, if it
524# is preferred to always offer frame pointers as a config
525# option on the architecture (regardless of KERNEL_DEBUG):
526#
527config ARCH_WANT_FRAME_POINTERS
528	bool
529
530config FRAME_POINTER
531	bool "Compile the kernel with frame pointers"
532	depends on DEBUG_KERNEL && (M68K || UML || SUPERH) || ARCH_WANT_FRAME_POINTERS
533	default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
534	help
535	  If you say Y here the resulting kernel image will be slightly
536	  larger and slower, but it gives very useful debugging information
537	  in case of kernel bugs. (precise oopses/stacktraces/warnings)
538
539config OBJTOOL
540	bool
541
542config STACK_VALIDATION
543	bool "Compile-time stack metadata validation"
544	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
545	select OBJTOOL
546	default n
547	help
548	  Validate frame pointer rules at compile-time.  This helps ensure that
549	  runtime stack traces are more reliable.
550
551	  For more information, see
552	  tools/objtool/Documentation/objtool.txt.
553
554config NOINSTR_VALIDATION
555	bool
556	depends on HAVE_NOINSTR_VALIDATION && DEBUG_ENTRY
557	select OBJTOOL
558	default y
559
560config VMLINUX_MAP
561	bool "Generate vmlinux.map file when linking"
562	depends on EXPERT
563	help
564	  Selecting this option will pass "-Map=vmlinux.map" to ld
565	  when linking vmlinux. That file can be useful for verifying
566	  and debugging magic section games, and for seeing which
567	  pieces of code get eliminated with
568	  CONFIG_LD_DEAD_CODE_DATA_ELIMINATION.
569
570config DEBUG_FORCE_WEAK_PER_CPU
571	bool "Force weak per-cpu definitions"
572	depends on DEBUG_KERNEL
573	help
574	  s390 and alpha require percpu variables in modules to be
575	  defined weak to work around addressing range issue which
576	  puts the following two restrictions on percpu variable
577	  definitions.
578
579	  1. percpu symbols must be unique whether static or not
580	  2. percpu variables can't be defined inside a function
581
582	  To ensure that generic code follows the above rules, this
583	  option forces all percpu variables to be defined as weak.
584
585endmenu # "Compiler options"
586
587menu "Generic Kernel Debugging Instruments"
588
589config MAGIC_SYSRQ
590	bool "Magic SysRq key"
591	depends on !UML
592	help
593	  If you say Y here, you will have some control over the system even
594	  if the system crashes for example during kernel debugging (e.g., you
595	  will be able to flush the buffer cache to disk, reboot the system
596	  immediately or dump some status information). This is accomplished
597	  by pressing various keys while holding SysRq (Alt+PrintScreen). It
598	  also works on a serial console (on PC hardware at least), if you
599	  send a BREAK and then within 5 seconds a command keypress. The
600	  keys are documented in <file:Documentation/admin-guide/sysrq.rst>.
601	  Don't say Y unless you really know what this hack does.
602
603config MAGIC_SYSRQ_DEFAULT_ENABLE
604	hex "Enable magic SysRq key functions by default"
605	depends on MAGIC_SYSRQ
606	default 0x1
607	help
608	  Specifies which SysRq key functions are enabled by default.
609	  This may be set to 1 or 0 to enable or disable them all, or
610	  to a bitmask as described in Documentation/admin-guide/sysrq.rst.
611
612config MAGIC_SYSRQ_SERIAL
613	bool "Enable magic SysRq key over serial"
614	depends on MAGIC_SYSRQ
615	default y
616	help
617	  Many embedded boards have a disconnected TTL level serial which can
618	  generate some garbage that can lead to spurious false sysrq detects.
619	  This option allows you to decide whether you want to enable the
620	  magic SysRq key.
621
622config MAGIC_SYSRQ_SERIAL_SEQUENCE
623	string "Char sequence that enables magic SysRq over serial"
624	depends on MAGIC_SYSRQ_SERIAL
625	default ""
626	help
627	  Specifies a sequence of characters that can follow BREAK to enable
628	  SysRq on a serial console.
629
630	  If unsure, leave an empty string and the option will not be enabled.
631
632config DEBUG_FS
633	bool "Debug Filesystem"
634	help
635	  debugfs is a virtual file system that kernel developers use to put
636	  debugging files into.  Enable this option to be able to read and
637	  write to these files.
638
639	  For detailed documentation on the debugfs API, see
640	  Documentation/filesystems/.
641
642	  If unsure, say N.
643
644choice
645	prompt "Debugfs default access"
646	depends on DEBUG_FS
647	default DEBUG_FS_ALLOW_ALL
648	help
649	  This selects the default access restrictions for debugfs.
650	  It can be overridden with kernel command line option
651	  debugfs=[on,no-mount,off]. The restrictions apply for API access
652	  and filesystem registration.
653
654config DEBUG_FS_ALLOW_ALL
655	bool "Access normal"
656	help
657	  No restrictions apply. Both API and filesystem registration
658	  is on. This is the normal default operation.
659
660config DEBUG_FS_DISALLOW_MOUNT
661	bool "Do not register debugfs as filesystem"
662	help
663	  The API is open but filesystem is not loaded. Clients can still do
664	  their work and read with debug tools that do not need
665	  debugfs filesystem.
666
667config DEBUG_FS_ALLOW_NONE
668	bool "No access"
669	help
670	  Access is off. Clients get -PERM when trying to create nodes in
671	  debugfs tree and debugfs is not registered as a filesystem.
672	  Client can then back-off or continue without debugfs access.
673
674endchoice
675
676source "lib/Kconfig.kgdb"
677source "lib/Kconfig.ubsan"
678source "lib/Kconfig.kcsan"
679
680endmenu
681
682menu "Networking Debugging"
683
684source "net/Kconfig.debug"
685
686endmenu # "Networking Debugging"
687
688menu "Memory Debugging"
689
690source "mm/Kconfig.debug"
691
692config DEBUG_OBJECTS
693	bool "Debug object operations"
694	depends on DEBUG_KERNEL
695	help
696	  If you say Y here, additional code will be inserted into the
697	  kernel to track the life time of various objects and validate
698	  the operations on those objects.
699
700config DEBUG_OBJECTS_SELFTEST
701	bool "Debug objects selftest"
702	depends on DEBUG_OBJECTS
703	help
704	  This enables the selftest of the object debug code.
705
706config DEBUG_OBJECTS_FREE
707	bool "Debug objects in freed memory"
708	depends on DEBUG_OBJECTS
709	help
710	  This enables checks whether a k/v free operation frees an area
711	  which contains an object which has not been deactivated
712	  properly. This can make kmalloc/kfree-intensive workloads
713	  much slower.
714
715config DEBUG_OBJECTS_TIMERS
716	bool "Debug timer objects"
717	depends on DEBUG_OBJECTS
718	help
719	  If you say Y here, additional code will be inserted into the
720	  timer routines to track the life time of timer objects and
721	  validate the timer operations.
722
723config DEBUG_OBJECTS_WORK
724	bool "Debug work objects"
725	depends on DEBUG_OBJECTS
726	help
727	  If you say Y here, additional code will be inserted into the
728	  work queue routines to track the life time of work objects and
729	  validate the work operations.
730
731config DEBUG_OBJECTS_RCU_HEAD
732	bool "Debug RCU callbacks objects"
733	depends on DEBUG_OBJECTS
734	help
735	  Enable this to turn on debugging of RCU list heads (call_rcu() usage).
736
737config DEBUG_OBJECTS_PERCPU_COUNTER
738	bool "Debug percpu counter objects"
739	depends on DEBUG_OBJECTS
740	help
741	  If you say Y here, additional code will be inserted into the
742	  percpu counter routines to track the life time of percpu counter
743	  objects and validate the percpu counter operations.
744
745config DEBUG_OBJECTS_ENABLE_DEFAULT
746	int "debug_objects bootup default value (0-1)"
747	range 0 1
748	default "1"
749	depends on DEBUG_OBJECTS
750	help
751	  Debug objects boot parameter default value
752
753config SHRINKER_DEBUG
754	bool "Enable shrinker debugging support"
755	depends on DEBUG_FS
756	help
757	  Say Y to enable the shrinker debugfs interface which provides
758	  visibility into the kernel memory shrinkers subsystem.
759	  Disable it to avoid an extra memory footprint.
760
761config DEBUG_STACK_USAGE
762	bool "Stack utilization instrumentation"
763	depends on DEBUG_KERNEL
764	help
765	  Enables the display of the minimum amount of free stack which each
766	  task has ever had available in the sysrq-T and sysrq-P debug output.
767
768	  This option will slow down process creation somewhat.
769
770config SCHED_STACK_END_CHECK
771	bool "Detect stack corruption on calls to schedule()"
772	depends on DEBUG_KERNEL
773	default n
774	help
775	  This option checks for a stack overrun on calls to schedule().
776	  If the stack end location is found to be over written always panic as
777	  the content of the corrupted region can no longer be trusted.
778	  This is to ensure no erroneous behaviour occurs which could result in
779	  data corruption or a sporadic crash at a later stage once the region
780	  is examined. The runtime overhead introduced is minimal.
781
782config ARCH_HAS_DEBUG_VM_PGTABLE
783	bool
784	help
785	  An architecture should select this when it can successfully
786	  build and run DEBUG_VM_PGTABLE.
787
788config DEBUG_VM_IRQSOFF
789	def_bool DEBUG_VM && !PREEMPT_RT
790
791config DEBUG_VM
792	bool "Debug VM"
793	depends on DEBUG_KERNEL
794	help
795	  Enable this to turn on extended checks in the virtual-memory system
796	  that may impact performance.
797
798	  If unsure, say N.
799
800config DEBUG_VM_SHOOT_LAZIES
801	bool "Debug MMU_LAZY_TLB_SHOOTDOWN implementation"
802	depends on DEBUG_VM
803	depends on MMU_LAZY_TLB_SHOOTDOWN
804	help
805	  Enable additional IPIs that ensure lazy tlb mm references are removed
806	  before the mm is freed.
807
808	  If unsure, say N.
809
810config DEBUG_VM_MAPLE_TREE
811	bool "Debug VM maple trees"
812	depends on DEBUG_VM
813	select DEBUG_MAPLE_TREE
814	help
815	  Enable VM maple tree debugging information and extra validations.
816
817	  If unsure, say N.
818
819config DEBUG_VM_RB
820	bool "Debug VM red-black trees"
821	depends on DEBUG_VM
822	help
823	  Enable VM red-black tree debugging information and extra validations.
824
825	  If unsure, say N.
826
827config DEBUG_VM_PGFLAGS
828	bool "Debug page-flags operations"
829	depends on DEBUG_VM
830	help
831	  Enables extra validation on page flags operations.
832
833	  If unsure, say N.
834
835config DEBUG_VM_PGTABLE
836	bool "Debug arch page table for semantics compliance"
837	depends on MMU
838	depends on ARCH_HAS_DEBUG_VM_PGTABLE
839	default y if DEBUG_VM
840	help
841	  This option provides a debug method which can be used to test
842	  architecture page table helper functions on various platforms in
843	  verifying if they comply with expected generic MM semantics. This
844	  will help architecture code in making sure that any changes or
845	  new additions of these helpers still conform to expected
846	  semantics of the generic MM. Platforms will have to opt in for
847	  this through ARCH_HAS_DEBUG_VM_PGTABLE.
848
849	  If unsure, say N.
850
851config ARCH_HAS_DEBUG_VIRTUAL
852	bool
853
854config DEBUG_VIRTUAL
855	bool "Debug VM translations"
856	depends on DEBUG_KERNEL && ARCH_HAS_DEBUG_VIRTUAL
857	help
858	  Enable some costly sanity checks in virtual to page code. This can
859	  catch mistakes with virt_to_page() and friends.
860
861	  If unsure, say N.
862
863config DEBUG_NOMMU_REGIONS
864	bool "Debug the global anon/private NOMMU mapping region tree"
865	depends on DEBUG_KERNEL && !MMU
866	help
867	  This option causes the global tree of anonymous and private mapping
868	  regions to be regularly checked for invalid topology.
869
870config DEBUG_MEMORY_INIT
871	bool "Debug memory initialisation" if EXPERT
872	default !EXPERT
873	help
874	  Enable this for additional checks during memory initialisation.
875	  The sanity checks verify aspects of the VM such as the memory model
876	  and other information provided by the architecture. Verbose
877	  information will be printed at KERN_DEBUG loglevel depending
878	  on the mminit_loglevel= command-line option.
879
880	  If unsure, say Y
881
882config MEMORY_NOTIFIER_ERROR_INJECT
883	tristate "Memory hotplug notifier error injection module"
884	depends on MEMORY_HOTPLUG && NOTIFIER_ERROR_INJECTION
885	help
886	  This option provides the ability to inject artificial errors to
887	  memory hotplug notifier chain callbacks.  It is controlled through
888	  debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
889
890	  If the notifier call chain should be failed with some events
891	  notified, write the error code to "actions/<notifier event>/error".
892
893	  Example: Inject memory hotplug offline error (-12 == -ENOMEM)
894
895	  # cd /sys/kernel/debug/notifier-error-inject/memory
896	  # echo -12 > actions/MEM_GOING_OFFLINE/error
897	  # echo offline > /sys/devices/system/memory/memoryXXX/state
898	  bash: echo: write error: Cannot allocate memory
899
900	  To compile this code as a module, choose M here: the module will
901	  be called memory-notifier-error-inject.
902
903	  If unsure, say N.
904
905config DEBUG_PER_CPU_MAPS
906	bool "Debug access to per_cpu maps"
907	depends on DEBUG_KERNEL
908	depends on SMP
909	help
910	  Say Y to verify that the per_cpu map being accessed has
911	  been set up. This adds a fair amount of code to kernel memory
912	  and decreases performance.
913
914	  Say N if unsure.
915
916config DEBUG_KMAP_LOCAL
917	bool "Debug kmap_local temporary mappings"
918	depends on DEBUG_KERNEL && KMAP_LOCAL
919	help
920	  This option enables additional error checking for the kmap_local
921	  infrastructure.  Disable for production use.
922
923config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
924	bool
925
926config DEBUG_KMAP_LOCAL_FORCE_MAP
927	bool "Enforce kmap_local temporary mappings"
928	depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
929	select KMAP_LOCAL
930	select DEBUG_KMAP_LOCAL
931	help
932	  This option enforces temporary mappings through the kmap_local
933	  mechanism for non-highmem pages and on non-highmem systems.
934	  Disable this for production systems!
935
936config DEBUG_HIGHMEM
937	bool "Highmem debugging"
938	depends on DEBUG_KERNEL && HIGHMEM
939	select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
940	select DEBUG_KMAP_LOCAL
941	help
942	  This option enables additional error checking for high memory
943	  systems.  Disable for production systems.
944
945config HAVE_DEBUG_STACKOVERFLOW
946	bool
947
948config DEBUG_STACKOVERFLOW
949	bool "Check for stack overflows"
950	depends on DEBUG_KERNEL && HAVE_DEBUG_STACKOVERFLOW
951	help
952	  Say Y here if you want to check for overflows of kernel, IRQ
953	  and exception stacks (if your architecture uses them). This
954	  option will show detailed messages if free stack space drops
955	  below a certain limit.
956
957	  These kinds of bugs usually occur when call-chains in the
958	  kernel get too deep, especially when interrupts are
959	  involved.
960
961	  Use this in cases where you see apparently random memory
962	  corruption, especially if it appears in 'struct thread_info'
963
964	  If in doubt, say "N".
965
966source "lib/Kconfig.kasan"
967source "lib/Kconfig.kfence"
968source "lib/Kconfig.kmsan"
969
970endmenu # "Memory Debugging"
971
972config DEBUG_SHIRQ
973	bool "Debug shared IRQ handlers"
974	depends on DEBUG_KERNEL
975	help
976	  Enable this to generate a spurious interrupt just before a shared
977	  interrupt handler is deregistered (generating one when registering
978	  is currently disabled). Drivers need to handle this correctly. Some
979	  don't and need to be caught.
980
981menu "Debug Oops, Lockups and Hangs"
982
983config PANIC_ON_OOPS
984	bool "Panic on Oops"
985	help
986	  Say Y here to enable the kernel to panic when it oopses. This
987	  has the same effect as setting oops=panic on the kernel command
988	  line.
989
990	  This feature is useful to ensure that the kernel does not do
991	  anything erroneous after an oops which could result in data
992	  corruption or other issues.
993
994	  Say N if unsure.
995
996config PANIC_ON_OOPS_VALUE
997	int
998	range 0 1
999	default 0 if !PANIC_ON_OOPS
1000	default 1 if PANIC_ON_OOPS
1001
1002config PANIC_TIMEOUT
1003	int "panic timeout"
1004	default 0
1005	help
1006	  Set the timeout value (in seconds) until a reboot occurs when
1007	  the kernel panics. If n = 0, then we wait forever. A timeout
1008	  value n > 0 will wait n seconds before rebooting, while a timeout
1009	  value n < 0 will reboot immediately.
1010
1011config LOCKUP_DETECTOR
1012	bool
1013
1014config SOFTLOCKUP_DETECTOR
1015	bool "Detect Soft Lockups"
1016	depends on DEBUG_KERNEL && !S390
1017	select LOCKUP_DETECTOR
1018	help
1019	  Say Y here to enable the kernel to act as a watchdog to detect
1020	  soft lockups.
1021
1022	  Softlockups are bugs that cause the kernel to loop in kernel
1023	  mode for more than 20 seconds, without giving other tasks a
1024	  chance to run.  The current stack trace is displayed upon
1025	  detection and the system will stay locked up.
1026
1027config BOOTPARAM_SOFTLOCKUP_PANIC
1028	bool "Panic (Reboot) On Soft Lockups"
1029	depends on SOFTLOCKUP_DETECTOR
1030	help
1031	  Say Y here to enable the kernel to panic on "soft lockups",
1032	  which are bugs that cause the kernel to loop in kernel
1033	  mode for more than 20 seconds (configurable using the watchdog_thresh
1034	  sysctl), without giving other tasks a chance to run.
1035
1036	  The panic can be used in combination with panic_timeout,
1037	  to cause the system to reboot automatically after a
1038	  lockup has been detected. This feature is useful for
1039	  high-availability systems that have uptime guarantees and
1040	  where a lockup must be resolved ASAP.
1041
1042	  Say N if unsure.
1043
1044config HAVE_HARDLOCKUP_DETECTOR_BUDDY
1045	bool
1046	depends on SMP
1047	default y
1048
1049#
1050# Global switch whether to build a hardlockup detector at all. It is available
1051# only when the architecture supports at least one implementation. There are
1052# two exceptions. The hardlockup detector is never enabled on:
1053#
1054#	s390: it reported many false positives there
1055#
1056#	sparc64: has a custom implementation which is not using the common
1057#		hardlockup command line options and sysctl interface.
1058#
1059config HARDLOCKUP_DETECTOR
1060	bool "Detect Hard Lockups"
1061	depends on DEBUG_KERNEL && !S390 && !HARDLOCKUP_DETECTOR_SPARC64
1062	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY || HAVE_HARDLOCKUP_DETECTOR_ARCH
1063	imply HARDLOCKUP_DETECTOR_PERF
1064	imply HARDLOCKUP_DETECTOR_BUDDY
1065	imply HARDLOCKUP_DETECTOR_ARCH
1066	select LOCKUP_DETECTOR
1067
1068	help
1069	  Say Y here to enable the kernel to act as a watchdog to detect
1070	  hard lockups.
1071
1072	  Hardlockups are bugs that cause the CPU to loop in kernel mode
1073	  for more than 10 seconds, without letting other interrupts have a
1074	  chance to run.  The current stack trace is displayed upon detection
1075	  and the system will stay locked up.
1076
1077#
1078# Note that arch-specific variants are always preferred.
1079#
1080config HARDLOCKUP_DETECTOR_PREFER_BUDDY
1081	bool "Prefer the buddy CPU hardlockup detector"
1082	depends on HARDLOCKUP_DETECTOR
1083	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && HAVE_HARDLOCKUP_DETECTOR_BUDDY
1084	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1085	help
1086	  Say Y here to prefer the buddy hardlockup detector over the perf one.
1087
1088	  With the buddy detector, each CPU uses its softlockup hrtimer
1089	  to check that the next CPU is processing hrtimer interrupts by
1090	  verifying that a counter is increasing.
1091
1092	  This hardlockup detector is useful on systems that don't have
1093	  an arch-specific hardlockup detector or if resources needed
1094	  for the hardlockup detector are better used for other things.
1095
1096config HARDLOCKUP_DETECTOR_PERF
1097	bool
1098	depends on HARDLOCKUP_DETECTOR
1099	depends on HAVE_HARDLOCKUP_DETECTOR_PERF && !HARDLOCKUP_DETECTOR_PREFER_BUDDY
1100	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1101	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1102
1103config HARDLOCKUP_DETECTOR_BUDDY
1104	bool
1105	depends on HARDLOCKUP_DETECTOR
1106	depends on HAVE_HARDLOCKUP_DETECTOR_BUDDY
1107	depends on !HAVE_HARDLOCKUP_DETECTOR_PERF || HARDLOCKUP_DETECTOR_PREFER_BUDDY
1108	depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
1109	select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1110
1111config HARDLOCKUP_DETECTOR_ARCH
1112	bool
1113	depends on HARDLOCKUP_DETECTOR
1114	depends on HAVE_HARDLOCKUP_DETECTOR_ARCH
1115	help
1116	  The arch-specific implementation of the hardlockup detector will
1117	  be used.
1118
1119#
1120# Both the "perf" and "buddy" hardlockup detectors count hrtimer
1121# interrupts. This config enables functions managing this common code.
1122#
1123config HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
1124	bool
1125	select SOFTLOCKUP_DETECTOR
1126
1127#
1128# Enables a timestamp based low pass filter to compensate for perf based
1129# hard lockup detection which runs too fast due to turbo modes.
1130#
1131config HARDLOCKUP_CHECK_TIMESTAMP
1132	bool
1133
1134config BOOTPARAM_HARDLOCKUP_PANIC
1135	bool "Panic (Reboot) On Hard Lockups"
1136	depends on HARDLOCKUP_DETECTOR
1137	help
1138	  Say Y here to enable the kernel to panic on "hard lockups",
1139	  which are bugs that cause the kernel to loop in kernel
1140	  mode with interrupts disabled for more than 10 seconds (configurable
1141	  using the watchdog_thresh sysctl).
1142
1143	  Say N if unsure.
1144
1145config DETECT_HUNG_TASK
1146	bool "Detect Hung Tasks"
1147	depends on DEBUG_KERNEL
1148	default SOFTLOCKUP_DETECTOR
1149	help
1150	  Say Y here to enable the kernel to detect "hung tasks",
1151	  which are bugs that cause the task to be stuck in
1152	  uninterruptible "D" state indefinitely.
1153
1154	  When a hung task is detected, the kernel will print the
1155	  current stack trace (which you should report), but the
1156	  task will stay in uninterruptible state. If lockdep is
1157	  enabled then all held locks will also be reported. This
1158	  feature has negligible overhead.
1159
1160config DEFAULT_HUNG_TASK_TIMEOUT
1161	int "Default timeout for hung task detection (in seconds)"
1162	depends on DETECT_HUNG_TASK
1163	default 120
1164	help
1165	  This option controls the default timeout (in seconds) used
1166	  to determine when a task has become non-responsive and should
1167	  be considered hung.
1168
1169	  It can be adjusted at runtime via the kernel.hung_task_timeout_secs
1170	  sysctl or by writing a value to
1171	  /proc/sys/kernel/hung_task_timeout_secs.
1172
1173	  A timeout of 0 disables the check.  The default is two minutes.
1174	  Keeping the default should be fine in most cases.
1175
1176config BOOTPARAM_HUNG_TASK_PANIC
1177	bool "Panic (Reboot) On Hung Tasks"
1178	depends on DETECT_HUNG_TASK
1179	help
1180	  Say Y here to enable the kernel to panic on "hung tasks",
1181	  which are bugs that cause the kernel to leave a task stuck
1182	  in uninterruptible "D" state.
1183
1184	  The panic can be used in combination with panic_timeout,
1185	  to cause the system to reboot automatically after a
1186	  hung task has been detected. This feature is useful for
1187	  high-availability systems that have uptime guarantees and
1188	  where a hung tasks must be resolved ASAP.
1189
1190	  Say N if unsure.
1191
1192config WQ_WATCHDOG
1193	bool "Detect Workqueue Stalls"
1194	depends on DEBUG_KERNEL
1195	help
1196	  Say Y here to enable stall detection on workqueues.  If a
1197	  worker pool doesn't make forward progress on a pending work
1198	  item for over a given amount of time, 30s by default, a
1199	  warning message is printed along with dump of workqueue
1200	  state.  This can be configured through kernel parameter
1201	  "workqueue.watchdog_thresh" and its sysfs counterpart.
1202
1203config WQ_CPU_INTENSIVE_REPORT
1204	bool "Report per-cpu work items which hog CPU for too long"
1205	depends on DEBUG_KERNEL
1206	help
1207	  Say Y here to enable reporting of concurrency-managed per-cpu work
1208	  items that hog CPUs for longer than
1209	  workqueue.cpu_intensive_thresh_us. Workqueue automatically
1210	  detects and excludes them from concurrency management to prevent
1211	  them from stalling other per-cpu work items. Occassional
1212	  triggering may not necessarily indicate a problem. Repeated
1213	  triggering likely indicates that the work item should be switched
1214	  to use an unbound workqueue.
1215
1216config TEST_LOCKUP
1217	tristate "Test module to generate lockups"
1218	depends on m
1219	help
1220	  This builds the "test_lockup" module that helps to make sure
1221	  that watchdogs and lockup detectors are working properly.
1222
1223	  Depending on module parameters it could emulate soft or hard
1224	  lockup, "hung task", or locking arbitrary lock for a long time.
1225	  Also it could generate series of lockups with cooling-down periods.
1226
1227	  If unsure, say N.
1228
1229endmenu # "Debug lockups and hangs"
1230
1231menu "Scheduler Debugging"
1232
1233config SCHED_DEBUG
1234	bool "Collect scheduler debugging info"
1235	depends on DEBUG_KERNEL && DEBUG_FS
1236	default y
1237	help
1238	  If you say Y here, the /sys/kernel/debug/sched file will be provided
1239	  that can help debug the scheduler. The runtime overhead of this
1240	  option is minimal.
1241
1242config SCHED_INFO
1243	bool
1244	default n
1245
1246config SCHEDSTATS
1247	bool "Collect scheduler statistics"
1248	depends on DEBUG_KERNEL && PROC_FS
1249	select SCHED_INFO
1250	help
1251	  If you say Y here, additional code will be inserted into the
1252	  scheduler and related routines to collect statistics about
1253	  scheduler behavior and provide them in /proc/schedstat.  These
1254	  stats may be useful for both tuning and debugging the scheduler
1255	  If you aren't debugging the scheduler or trying to tune a specific
1256	  application, you can say N to avoid the very slight overhead
1257	  this adds.
1258
1259endmenu
1260
1261config DEBUG_TIMEKEEPING
1262	bool "Enable extra timekeeping sanity checking"
1263	help
1264	  This option will enable additional timekeeping sanity checks
1265	  which may be helpful when diagnosing issues where timekeeping
1266	  problems are suspected.
1267
1268	  This may include checks in the timekeeping hotpaths, so this
1269	  option may have a (very small) performance impact to some
1270	  workloads.
1271
1272	  If unsure, say N.
1273
1274config DEBUG_PREEMPT
1275	bool "Debug preemptible kernel"
1276	depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT
1277	help
1278	  If you say Y here then the kernel will use a debug variant of the
1279	  commonly used smp_processor_id() function and will print warnings
1280	  if kernel code uses it in a preemption-unsafe way. Also, the kernel
1281	  will detect preemption count underflows.
1282
1283	  This option has potential to introduce high runtime overhead,
1284	  depending on workload as it triggers debugging routines for each
1285	  this_cpu operation. It should only be used for debugging purposes.
1286
1287menu "Lock Debugging (spinlocks, mutexes, etc...)"
1288
1289config LOCK_DEBUGGING_SUPPORT
1290	bool
1291	depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
1292	default y
1293
1294config PROVE_LOCKING
1295	bool "Lock debugging: prove locking correctness"
1296	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1297	select LOCKDEP
1298	select DEBUG_SPINLOCK
1299	select DEBUG_MUTEXES if !PREEMPT_RT
1300	select DEBUG_RT_MUTEXES if RT_MUTEXES
1301	select DEBUG_RWSEMS
1302	select DEBUG_WW_MUTEX_SLOWPATH
1303	select DEBUG_LOCK_ALLOC
1304	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
1305	select TRACE_IRQFLAGS
1306	default n
1307	help
1308	 This feature enables the kernel to prove that all locking
1309	 that occurs in the kernel runtime is mathematically
1310	 correct: that under no circumstance could an arbitrary (and
1311	 not yet triggered) combination of observed locking
1312	 sequences (on an arbitrary number of CPUs, running an
1313	 arbitrary number of tasks and interrupt contexts) cause a
1314	 deadlock.
1315
1316	 In short, this feature enables the kernel to report locking
1317	 related deadlocks before they actually occur.
1318
1319	 The proof does not depend on how hard and complex a
1320	 deadlock scenario would be to trigger: how many
1321	 participant CPUs, tasks and irq-contexts would be needed
1322	 for it to trigger. The proof also does not depend on
1323	 timing: if a race and a resulting deadlock is possible
1324	 theoretically (no matter how unlikely the race scenario
1325	 is), it will be proven so and will immediately be
1326	 reported by the kernel (once the event is observed that
1327	 makes the deadlock theoretically possible).
1328
1329	 If a deadlock is impossible (i.e. the locking rules, as
1330	 observed by the kernel, are mathematically correct), the
1331	 kernel reports nothing.
1332
1333	 NOTE: this feature can also be enabled for rwlocks, mutexes
1334	 and rwsems - in which case all dependencies between these
1335	 different locking variants are observed and mapped too, and
1336	 the proof of observed correctness is also maintained for an
1337	 arbitrary combination of these separate locking variants.
1338
1339	 For more details, see Documentation/locking/lockdep-design.rst.
1340
1341config PROVE_RAW_LOCK_NESTING
1342	bool "Enable raw_spinlock - spinlock nesting checks"
1343	depends on PROVE_LOCKING
1344	default n
1345	help
1346	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
1347	 that the lock nesting rules for PREEMPT_RT enabled kernels are
1348	 not violated.
1349
1350	 NOTE: There are known nesting problems. So if you enable this
1351	 option expect lockdep splats until these problems have been fully
1352	 addressed which is work in progress. This config switch allows to
1353	 identify and analyze these problems. It will be removed and the
1354	 check permanently enabled once the main issues have been fixed.
1355
1356	 If unsure, select N.
1357
1358config LOCK_STAT
1359	bool "Lock usage statistics"
1360	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1361	select LOCKDEP
1362	select DEBUG_SPINLOCK
1363	select DEBUG_MUTEXES if !PREEMPT_RT
1364	select DEBUG_RT_MUTEXES if RT_MUTEXES
1365	select DEBUG_LOCK_ALLOC
1366	default n
1367	help
1368	 This feature enables tracking lock contention points
1369
1370	 For more details, see Documentation/locking/lockstat.rst
1371
1372	 This also enables lock events required by "perf lock",
1373	 subcommand of perf.
1374	 If you want to use "perf lock", you also need to turn on
1375	 CONFIG_EVENT_TRACING.
1376
1377	 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
1378	 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
1379
1380config DEBUG_RT_MUTEXES
1381	bool "RT Mutex debugging, deadlock detection"
1382	depends on DEBUG_KERNEL && RT_MUTEXES
1383	help
1384	 This allows rt mutex semantics violations and rt mutex related
1385	 deadlocks (lockups) to be detected and reported automatically.
1386
1387config DEBUG_SPINLOCK
1388	bool "Spinlock and rw-lock debugging: basic checks"
1389	depends on DEBUG_KERNEL
1390	select UNINLINE_SPIN_UNLOCK
1391	help
1392	  Say Y here and build SMP to catch missing spinlock initialization
1393	  and certain other kinds of spinlock errors commonly made.  This is
1394	  best used in conjunction with the NMI watchdog so that spinlock
1395	  deadlocks are also debuggable.
1396
1397config DEBUG_MUTEXES
1398	bool "Mutex debugging: basic checks"
1399	depends on DEBUG_KERNEL && !PREEMPT_RT
1400	help
1401	 This feature allows mutex semantics violations to be detected and
1402	 reported.
1403
1404config DEBUG_WW_MUTEX_SLOWPATH
1405	bool "Wait/wound mutex debugging: Slowpath testing"
1406	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1407	select DEBUG_LOCK_ALLOC
1408	select DEBUG_SPINLOCK
1409	select DEBUG_MUTEXES if !PREEMPT_RT
1410	select DEBUG_RT_MUTEXES if PREEMPT_RT
1411	help
1412	 This feature enables slowpath testing for w/w mutex users by
1413	 injecting additional -EDEADLK wound/backoff cases. Together with
1414	 the full mutex checks enabled with (CONFIG_PROVE_LOCKING) this
1415	 will test all possible w/w mutex interface abuse with the
1416	 exception of simply not acquiring all the required locks.
1417	 Note that this feature can introduce significant overhead, so
1418	 it really should not be enabled in a production or distro kernel,
1419	 even a debug kernel.  If you are a driver writer, enable it.  If
1420	 you are a distro, do not.
1421
1422config DEBUG_RWSEMS
1423	bool "RW Semaphore debugging: basic checks"
1424	depends on DEBUG_KERNEL
1425	help
1426	  This debugging feature allows mismatched rw semaphore locks
1427	  and unlocks to be detected and reported.
1428
1429config DEBUG_LOCK_ALLOC
1430	bool "Lock debugging: detect incorrect freeing of live locks"
1431	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1432	select DEBUG_SPINLOCK
1433	select DEBUG_MUTEXES if !PREEMPT_RT
1434	select DEBUG_RT_MUTEXES if RT_MUTEXES
1435	select LOCKDEP
1436	help
1437	 This feature will check whether any held lock (spinlock, rwlock,
1438	 mutex or rwsem) is incorrectly freed by the kernel, via any of the
1439	 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
1440	 vfree(), etc.), whether a live lock is incorrectly reinitialized via
1441	 spin_lock_init()/mutex_init()/etc., or whether there is any lock
1442	 held during task exit.
1443
1444config LOCKDEP
1445	bool
1446	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
1447	select STACKTRACE
1448	select KALLSYMS
1449	select KALLSYMS_ALL
1450
1451config LOCKDEP_SMALL
1452	bool
1453
1454config LOCKDEP_BITS
1455	int "Bitsize for MAX_LOCKDEP_ENTRIES"
1456	depends on LOCKDEP && !LOCKDEP_SMALL
1457	range 10 30
1458	default 15
1459	help
1460	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_ENTRIES too low!" message.
1461
1462config LOCKDEP_CHAINS_BITS
1463	int "Bitsize for MAX_LOCKDEP_CHAINS"
1464	depends on LOCKDEP && !LOCKDEP_SMALL
1465	range 10 30
1466	default 16
1467	help
1468	  Try increasing this value if you hit "BUG: MAX_LOCKDEP_CHAINS too low!" message.
1469
1470config LOCKDEP_STACK_TRACE_BITS
1471	int "Bitsize for MAX_STACK_TRACE_ENTRIES"
1472	depends on LOCKDEP && !LOCKDEP_SMALL
1473	range 10 30
1474	default 19
1475	help
1476	  Try increasing this value if you hit "BUG: MAX_STACK_TRACE_ENTRIES too low!" message.
1477
1478config LOCKDEP_STACK_TRACE_HASH_BITS
1479	int "Bitsize for STACK_TRACE_HASH_SIZE"
1480	depends on LOCKDEP && !LOCKDEP_SMALL
1481	range 10 30
1482	default 14
1483	help
1484	  Try increasing this value if you need large STACK_TRACE_HASH_SIZE.
1485
1486config LOCKDEP_CIRCULAR_QUEUE_BITS
1487	int "Bitsize for elements in circular_queue struct"
1488	depends on LOCKDEP
1489	range 10 30
1490	default 12
1491	help
1492	  Try increasing this value if you hit "lockdep bfs error:-1" warning due to __cq_enqueue() failure.
1493
1494config DEBUG_LOCKDEP
1495	bool "Lock dependency engine debugging"
1496	depends on DEBUG_KERNEL && LOCKDEP
1497	select DEBUG_IRQFLAGS
1498	help
1499	  If you say Y here, the lock dependency engine will do
1500	  additional runtime checks to debug itself, at the price
1501	  of more runtime overhead.
1502
1503config DEBUG_ATOMIC_SLEEP
1504	bool "Sleep inside atomic section checking"
1505	select PREEMPT_COUNT
1506	depends on DEBUG_KERNEL
1507	depends on !ARCH_NO_PREEMPT
1508	help
1509	  If you say Y here, various routines which may sleep will become very
1510	  noisy if they are called inside atomic sections: when a spinlock is
1511	  held, inside an rcu read side critical section, inside preempt disabled
1512	  sections, inside an interrupt, etc...
1513
1514config DEBUG_LOCKING_API_SELFTESTS
1515	bool "Locking API boot-time self-tests"
1516	depends on DEBUG_KERNEL
1517	help
1518	  Say Y here if you want the kernel to run a short self-test during
1519	  bootup. The self-test checks whether common types of locking bugs
1520	  are detected by debugging mechanisms or not. (if you disable
1521	  lock debugging then those bugs won't be detected of course.)
1522	  The following locking APIs are covered: spinlocks, rwlocks,
1523	  mutexes and rwsems.
1524
1525config LOCK_TORTURE_TEST
1526	tristate "torture tests for locking"
1527	depends on DEBUG_KERNEL
1528	select TORTURE_TEST
1529	help
1530	  This option provides a kernel module that runs torture tests
1531	  on kernel locking primitives.  The kernel module may be built
1532	  after the fact on the running kernel to be tested, if desired.
1533
1534	  Say Y here if you want kernel locking-primitive torture tests
1535	  to be built into the kernel.
1536	  Say M if you want these torture tests to build as a module.
1537	  Say N if you are unsure.
1538
1539config WW_MUTEX_SELFTEST
1540	tristate "Wait/wound mutex selftests"
1541	help
1542	  This option provides a kernel module that runs tests on the
1543	  on the struct ww_mutex locking API.
1544
1545	  It is recommended to enable DEBUG_WW_MUTEX_SLOWPATH in conjunction
1546	  with this test harness.
1547
1548	  Say M if you want these self tests to build as a module.
1549	  Say N if you are unsure.
1550
1551config SCF_TORTURE_TEST
1552	tristate "torture tests for smp_call_function*()"
1553	depends on DEBUG_KERNEL
1554	select TORTURE_TEST
1555	help
1556	  This option provides a kernel module that runs torture tests
1557	  on the smp_call_function() family of primitives.  The kernel
1558	  module may be built after the fact on the running kernel to
1559	  be tested, if desired.
1560
1561config CSD_LOCK_WAIT_DEBUG
1562	bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
1563	depends on DEBUG_KERNEL
1564	depends on 64BIT
1565	default n
1566	help
1567	  This option enables debug prints when CPUs are slow to respond
1568	  to the smp_call_function*() IPI wrappers.  These debug prints
1569	  include the IPI handler function currently executing (if any)
1570	  and relevant stack traces.
1571
1572config CSD_LOCK_WAIT_DEBUG_DEFAULT
1573	bool "Default csd_lock_wait() debugging on at boot time"
1574	depends on CSD_LOCK_WAIT_DEBUG
1575	depends on 64BIT
1576	default n
1577	help
1578	  This option causes the csdlock_debug= kernel boot parameter to
1579	  default to 1 (basic debugging) instead of 0 (no debugging).
1580
1581endmenu # lock debugging
1582
1583config TRACE_IRQFLAGS
1584	depends on TRACE_IRQFLAGS_SUPPORT
1585	bool
1586	help
1587	  Enables hooks to interrupt enabling and disabling for
1588	  either tracing or lock debugging.
1589
1590config TRACE_IRQFLAGS_NMI
1591	def_bool y
1592	depends on TRACE_IRQFLAGS
1593	depends on TRACE_IRQFLAGS_NMI_SUPPORT
1594
1595config NMI_CHECK_CPU
1596	bool "Debugging for CPUs failing to respond to backtrace requests"
1597	depends on DEBUG_KERNEL
1598	depends on X86
1599	default n
1600	help
1601	  Enables debug prints when a CPU fails to respond to a given
1602	  backtrace NMI.  These prints provide some reasons why a CPU
1603	  might legitimately be failing to respond, for example, if it
1604	  is offline of if ignore_nmis is set.
1605
1606config DEBUG_IRQFLAGS
1607	bool "Debug IRQ flag manipulation"
1608	help
1609	  Enables checks for potentially unsafe enabling or disabling of
1610	  interrupts, such as calling raw_local_irq_restore() when interrupts
1611	  are enabled.
1612
1613config STACKTRACE
1614	bool "Stack backtrace support"
1615	depends on STACKTRACE_SUPPORT
1616	help
1617	  This option causes the kernel to create a /proc/pid/stack for
1618	  every process, showing its current stack trace.
1619	  It is also used by various kernel debugging features that require
1620	  stack trace generation.
1621
1622config WARN_ALL_UNSEEDED_RANDOM
1623	bool "Warn for all uses of unseeded randomness"
1624	default n
1625	help
1626	  Some parts of the kernel contain bugs relating to their use of
1627	  cryptographically secure random numbers before it's actually possible
1628	  to generate those numbers securely. This setting ensures that these
1629	  flaws don't go unnoticed, by enabling a message, should this ever
1630	  occur. This will allow people with obscure setups to know when things
1631	  are going wrong, so that they might contact developers about fixing
1632	  it.
1633
1634	  Unfortunately, on some models of some architectures getting
1635	  a fully seeded CRNG is extremely difficult, and so this can
1636	  result in dmesg getting spammed for a surprisingly long
1637	  time.  This is really bad from a security perspective, and
1638	  so architecture maintainers really need to do what they can
1639	  to get the CRNG seeded sooner after the system is booted.
1640	  However, since users cannot do anything actionable to
1641	  address this, by default this option is disabled.
1642
1643	  Say Y here if you want to receive warnings for all uses of
1644	  unseeded randomness.  This will be of use primarily for
1645	  those developers interested in improving the security of
1646	  Linux kernels running on their architecture (or
1647	  subarchitecture).
1648
1649config DEBUG_KOBJECT
1650	bool "kobject debugging"
1651	depends on DEBUG_KERNEL
1652	help
1653	  If you say Y here, some extra kobject debugging messages will be sent
1654	  to the syslog.
1655
1656config DEBUG_KOBJECT_RELEASE
1657	bool "kobject release debugging"
1658	depends on DEBUG_OBJECTS_TIMERS
1659	help
1660	  kobjects are reference counted objects.  This means that their
1661	  last reference count put is not predictable, and the kobject can
1662	  live on past the point at which a driver decides to drop its
1663	  initial reference to the kobject gained on allocation.  An
1664	  example of this would be a struct device which has just been
1665	  unregistered.
1666
1667	  However, some buggy drivers assume that after such an operation,
1668	  the memory backing the kobject can be immediately freed.  This
1669	  goes completely against the principles of a refcounted object.
1670
1671	  If you say Y here, the kernel will delay the release of kobjects
1672	  on the last reference count to improve the visibility of this
1673	  kind of kobject release bug.
1674
1675config HAVE_DEBUG_BUGVERBOSE
1676	bool
1677
1678menu "Debug kernel data structures"
1679
1680config DEBUG_LIST
1681	bool "Debug linked list manipulation"
1682	depends on DEBUG_KERNEL
1683	select LIST_HARDENED
1684	help
1685	  Enable this to turn on extended checks in the linked-list walking
1686	  routines.
1687
1688	  This option trades better quality error reports for performance, and
1689	  is more suitable for kernel debugging. If you care about performance,
1690	  you should only enable CONFIG_LIST_HARDENED instead.
1691
1692	  If unsure, say N.
1693
1694config DEBUG_PLIST
1695	bool "Debug priority linked list manipulation"
1696	depends on DEBUG_KERNEL
1697	help
1698	  Enable this to turn on extended checks in the priority-ordered
1699	  linked-list (plist) walking routines.  This checks the entire
1700	  list multiple times during each manipulation.
1701
1702	  If unsure, say N.
1703
1704config DEBUG_SG
1705	bool "Debug SG table operations"
1706	depends on DEBUG_KERNEL
1707	help
1708	  Enable this to turn on checks on scatter-gather tables. This can
1709	  help find problems with drivers that do not properly initialize
1710	  their sg tables.
1711
1712	  If unsure, say N.
1713
1714config DEBUG_NOTIFIERS
1715	bool "Debug notifier call chains"
1716	depends on DEBUG_KERNEL
1717	help
1718	  Enable this to turn on sanity checking for notifier call chains.
1719	  This is most useful for kernel developers to make sure that
1720	  modules properly unregister themselves from notifier chains.
1721	  This is a relatively cheap check but if you care about maximum
1722	  performance, say N.
1723
1724config DEBUG_CLOSURES
1725	bool "Debug closures (bcache async widgits)"
1726	depends on CLOSURES
1727	select DEBUG_FS
1728	help
1729	  Keeps all active closures in a linked list and provides a debugfs
1730	  interface to list them, which makes it possible to see asynchronous
1731	  operations that get stuck.
1732
1733config DEBUG_MAPLE_TREE
1734	bool "Debug maple trees"
1735	depends on DEBUG_KERNEL
1736	help
1737	  Enable maple tree debugging information and extra validations.
1738
1739	  If unsure, say N.
1740
1741endmenu
1742
1743config DEBUG_CREDENTIALS
1744	bool "Debug credential management"
1745	depends on DEBUG_KERNEL
1746	help
1747	  Enable this to turn on some debug checking for credential
1748	  management.  The additional code keeps track of the number of
1749	  pointers from task_structs to any given cred struct, and checks to
1750	  see that this number never exceeds the usage count of the cred
1751	  struct.
1752
1753	  Furthermore, if SELinux is enabled, this also checks that the
1754	  security pointer in the cred struct is never seen to be invalid.
1755
1756	  If unsure, say N.
1757
1758source "kernel/rcu/Kconfig.debug"
1759
1760config DEBUG_WQ_FORCE_RR_CPU
1761	bool "Force round-robin CPU selection for unbound work items"
1762	depends on DEBUG_KERNEL
1763	default n
1764	help
1765	  Workqueue used to implicitly guarantee that work items queued
1766	  without explicit CPU specified are put on the local CPU.  This
1767	  guarantee is no longer true and while local CPU is still
1768	  preferred work items may be put on foreign CPUs.  Kernel
1769	  parameter "workqueue.debug_force_rr_cpu" is added to force
1770	  round-robin CPU selection to flush out usages which depend on the
1771	  now broken guarantee.  This config option enables the debug
1772	  feature by default.  When enabled, memory and cache locality will
1773	  be impacted.
1774
1775config CPU_HOTPLUG_STATE_CONTROL
1776	bool "Enable CPU hotplug state control"
1777	depends on DEBUG_KERNEL
1778	depends on HOTPLUG_CPU
1779	default n
1780	help
1781	  Allows to write steps between "offline" and "online" to the CPUs
1782	  sysfs target file so states can be stepped granular. This is a debug
1783	  option for now as the hotplug machinery cannot be stopped and
1784	  restarted at arbitrary points yet.
1785
1786	  Say N if your are unsure.
1787
1788config LATENCYTOP
1789	bool "Latency measuring infrastructure"
1790	depends on DEBUG_KERNEL
1791	depends on STACKTRACE_SUPPORT
1792	depends on PROC_FS
1793	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
1794	select KALLSYMS
1795	select KALLSYMS_ALL
1796	select STACKTRACE
1797	select SCHEDSTATS
1798	help
1799	  Enable this option if you want to use the LatencyTOP tool
1800	  to find out which userspace is blocking on what kernel operations.
1801
1802config DEBUG_CGROUP_REF
1803	bool "Disable inlining of cgroup css reference count functions"
1804	depends on DEBUG_KERNEL
1805	depends on CGROUPS
1806	depends on KPROBES
1807	default n
1808	help
1809	  Force cgroup css reference count functions to not be inlined so
1810	  that they can be kprobed for debugging.
1811
1812source "kernel/trace/Kconfig"
1813
1814config PROVIDE_OHCI1394_DMA_INIT
1815	bool "Remote debugging over FireWire early on boot"
1816	depends on PCI && X86
1817	help
1818	  If you want to debug problems which hang or crash the kernel early
1819	  on boot and the crashing machine has a FireWire port, you can use
1820	  this feature to remotely access the memory of the crashed machine
1821	  over FireWire. This employs remote DMA as part of the OHCI1394
1822	  specification which is now the standard for FireWire controllers.
1823
1824	  With remote DMA, you can monitor the printk buffer remotely using
1825	  firescope and access all memory below 4GB using fireproxy from gdb.
1826	  Even controlling a kernel debugger is possible using remote DMA.
1827
1828	  Usage:
1829
1830	  If ohci1394_dma=early is used as boot parameter, it will initialize
1831	  all OHCI1394 controllers which are found in the PCI config space.
1832
1833	  As all changes to the FireWire bus such as enabling and disabling
1834	  devices cause a bus reset and thereby disable remote DMA for all
1835	  devices, be sure to have the cable plugged and FireWire enabled on
1836	  the debugging host before booting the debug target for debugging.
1837
1838	  This code (~1k) is freed after boot. By then, the firewire stack
1839	  in charge of the OHCI-1394 controllers should be used instead.
1840
1841	  See Documentation/core-api/debugging-via-ohci1394.rst for more information.
1842
1843source "samples/Kconfig"
1844
1845config ARCH_HAS_DEVMEM_IS_ALLOWED
1846	bool
1847
1848config STRICT_DEVMEM
1849	bool "Filter access to /dev/mem"
1850	depends on MMU && DEVMEM
1851	depends on ARCH_HAS_DEVMEM_IS_ALLOWED || GENERIC_LIB_DEVMEM_IS_ALLOWED
1852	default y if PPC || X86 || ARM64
1853	help
1854	  If this option is disabled, you allow userspace (root) access to all
1855	  of memory, including kernel and userspace memory. Accidental
1856	  access to this is obviously disastrous, but specific access can
1857	  be used by people debugging the kernel. Note that with PAT support
1858	  enabled, even in this case there are restrictions on /dev/mem
1859	  use due to the cache aliasing requirements.
1860
1861	  If this option is switched on, and IO_STRICT_DEVMEM=n, the /dev/mem
1862	  file only allows userspace access to PCI space and the BIOS code and
1863	  data regions.  This is sufficient for dosemu and X and all common
1864	  users of /dev/mem.
1865
1866	  If in doubt, say Y.
1867
1868config IO_STRICT_DEVMEM
1869	bool "Filter I/O access to /dev/mem"
1870	depends on STRICT_DEVMEM
1871	help
1872	  If this option is disabled, you allow userspace (root) access to all
1873	  io-memory regardless of whether a driver is actively using that
1874	  range.  Accidental access to this is obviously disastrous, but
1875	  specific access can be used by people debugging kernel drivers.
1876
1877	  If this option is switched on, the /dev/mem file only allows
1878	  userspace access to *idle* io-memory ranges (see /proc/iomem) This
1879	  may break traditional users of /dev/mem (dosemu, legacy X, etc...)
1880	  if the driver using a given range cannot be disabled.
1881
1882	  If in doubt, say Y.
1883
1884menu "$(SRCARCH) Debugging"
1885
1886source "arch/$(SRCARCH)/Kconfig.debug"
1887
1888endmenu
1889
1890menu "Kernel Testing and Coverage"
1891
1892source "lib/kunit/Kconfig"
1893
1894config NOTIFIER_ERROR_INJECTION
1895	tristate "Notifier error injection"
1896	depends on DEBUG_KERNEL
1897	select DEBUG_FS
1898	help
1899	  This option provides the ability to inject artificial errors to
1900	  specified notifier chain callbacks. It is useful to test the error
1901	  handling of notifier call chain failures.
1902
1903	  Say N if unsure.
1904
1905config PM_NOTIFIER_ERROR_INJECT
1906	tristate "PM notifier error injection module"
1907	depends on PM && NOTIFIER_ERROR_INJECTION
1908	default m if PM_DEBUG
1909	help
1910	  This option provides the ability to inject artificial errors to
1911	  PM notifier chain callbacks.  It is controlled through debugfs
1912	  interface /sys/kernel/debug/notifier-error-inject/pm
1913
1914	  If the notifier call chain should be failed with some events
1915	  notified, write the error code to "actions/<notifier event>/error".
1916
1917	  Example: Inject PM suspend error (-12 = -ENOMEM)
1918
1919	  # cd /sys/kernel/debug/notifier-error-inject/pm/
1920	  # echo -12 > actions/PM_SUSPEND_PREPARE/error
1921	  # echo mem > /sys/power/state
1922	  bash: echo: write error: Cannot allocate memory
1923
1924	  To compile this code as a module, choose M here: the module will
1925	  be called pm-notifier-error-inject.
1926
1927	  If unsure, say N.
1928
1929config OF_RECONFIG_NOTIFIER_ERROR_INJECT
1930	tristate "OF reconfig notifier error injection module"
1931	depends on OF_DYNAMIC && NOTIFIER_ERROR_INJECTION
1932	help
1933	  This option provides the ability to inject artificial errors to
1934	  OF reconfig notifier chain callbacks.  It is controlled
1935	  through debugfs interface under
1936	  /sys/kernel/debug/notifier-error-inject/OF-reconfig/
1937
1938	  If the notifier call chain should be failed with some events
1939	  notified, write the error code to "actions/<notifier event>/error".
1940
1941	  To compile this code as a module, choose M here: the module will
1942	  be called of-reconfig-notifier-error-inject.
1943
1944	  If unsure, say N.
1945
1946config NETDEV_NOTIFIER_ERROR_INJECT
1947	tristate "Netdev notifier error injection module"
1948	depends on NET && NOTIFIER_ERROR_INJECTION
1949	help
1950	  This option provides the ability to inject artificial errors to
1951	  netdevice notifier chain callbacks.  It is controlled through debugfs
1952	  interface /sys/kernel/debug/notifier-error-inject/netdev
1953
1954	  If the notifier call chain should be failed with some events
1955	  notified, write the error code to "actions/<notifier event>/error".
1956
1957	  Example: Inject netdevice mtu change error (-22 = -EINVAL)
1958
1959	  # cd /sys/kernel/debug/notifier-error-inject/netdev
1960	  # echo -22 > actions/NETDEV_CHANGEMTU/error
1961	  # ip link set eth0 mtu 1024
1962	  RTNETLINK answers: Invalid argument
1963
1964	  To compile this code as a module, choose M here: the module will
1965	  be called netdev-notifier-error-inject.
1966
1967	  If unsure, say N.
1968
1969config FUNCTION_ERROR_INJECTION
1970	bool "Fault-injections of functions"
1971	depends on HAVE_FUNCTION_ERROR_INJECTION && KPROBES
1972	help
1973	  Add fault injections into various functions that are annotated with
1974	  ALLOW_ERROR_INJECTION() in the kernel. BPF may also modify the return
1975	  value of these functions. This is useful to test error paths of code.
1976
1977	  If unsure, say N
1978
1979config FAULT_INJECTION
1980	bool "Fault-injection framework"
1981	depends on DEBUG_KERNEL
1982	help
1983	  Provide fault-injection framework.
1984	  For more details, see Documentation/fault-injection/.
1985
1986config FAILSLAB
1987	bool "Fault-injection capability for kmalloc"
1988	depends on FAULT_INJECTION
1989	depends on SLAB || SLUB
1990	help
1991	  Provide fault-injection capability for kmalloc.
1992
1993config FAIL_PAGE_ALLOC
1994	bool "Fault-injection capability for alloc_pages()"
1995	depends on FAULT_INJECTION
1996	help
1997	  Provide fault-injection capability for alloc_pages().
1998
1999config FAULT_INJECTION_USERCOPY
2000	bool "Fault injection capability for usercopy functions"
2001	depends on FAULT_INJECTION
2002	help
2003	  Provides fault-injection capability to inject failures
2004	  in usercopy functions (copy_from_user(), get_user(), ...).
2005
2006config FAIL_MAKE_REQUEST
2007	bool "Fault-injection capability for disk IO"
2008	depends on FAULT_INJECTION && BLOCK
2009	help
2010	  Provide fault-injection capability for disk IO.
2011
2012config FAIL_IO_TIMEOUT
2013	bool "Fault-injection capability for faking disk interrupts"
2014	depends on FAULT_INJECTION && BLOCK
2015	help
2016	  Provide fault-injection capability on end IO handling. This
2017	  will make the block layer "forget" an interrupt as configured,
2018	  thus exercising the error handling.
2019
2020	  Only works with drivers that use the generic timeout handling,
2021	  for others it won't do anything.
2022
2023config FAIL_FUTEX
2024	bool "Fault-injection capability for futexes"
2025	select DEBUG_FS
2026	depends on FAULT_INJECTION && FUTEX
2027	help
2028	  Provide fault-injection capability for futexes.
2029
2030config FAULT_INJECTION_DEBUG_FS
2031	bool "Debugfs entries for fault-injection capabilities"
2032	depends on FAULT_INJECTION && SYSFS && DEBUG_FS
2033	help
2034	  Enable configuration of fault-injection capabilities via debugfs.
2035
2036config FAIL_FUNCTION
2037	bool "Fault-injection capability for functions"
2038	depends on FAULT_INJECTION_DEBUG_FS && FUNCTION_ERROR_INJECTION
2039	help
2040	  Provide function-based fault-injection capability.
2041	  This will allow you to override a specific function with a return
2042	  with given return value. As a result, function caller will see
2043	  an error value and have to handle it. This is useful to test the
2044	  error handling in various subsystems.
2045
2046config FAIL_MMC_REQUEST
2047	bool "Fault-injection capability for MMC IO"
2048	depends on FAULT_INJECTION_DEBUG_FS && MMC
2049	help
2050	  Provide fault-injection capability for MMC IO.
2051	  This will make the mmc core return data errors. This is
2052	  useful to test the error handling in the mmc block device
2053	  and to test how the mmc host driver handles retries from
2054	  the block device.
2055
2056config FAIL_SUNRPC
2057	bool "Fault-injection capability for SunRPC"
2058	depends on FAULT_INJECTION_DEBUG_FS && SUNRPC_DEBUG
2059	help
2060	  Provide fault-injection capability for SunRPC and
2061	  its consumers.
2062
2063config FAULT_INJECTION_CONFIGFS
2064	bool "Configfs interface for fault-injection capabilities"
2065	depends on FAULT_INJECTION
2066	select CONFIGFS_FS
2067	help
2068	  This option allows configfs-based drivers to dynamically configure
2069	  fault-injection via configfs.  Each parameter for driver-specific
2070	  fault-injection can be made visible as a configfs attribute in a
2071	  configfs group.
2072
2073
2074config FAULT_INJECTION_STACKTRACE_FILTER
2075	bool "stacktrace filter for fault-injection capabilities"
2076	depends on FAULT_INJECTION
2077	depends on (FAULT_INJECTION_DEBUG_FS || FAULT_INJECTION_CONFIGFS) && STACKTRACE_SUPPORT
2078	select STACKTRACE
2079	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
2080	help
2081	  Provide stacktrace filter for fault-injection capabilities
2082
2083config ARCH_HAS_KCOV
2084	bool
2085	help
2086	  An architecture should select this when it can successfully
2087	  build and run with CONFIG_KCOV. This typically requires
2088	  disabling instrumentation for some early boot code.
2089
2090config CC_HAS_SANCOV_TRACE_PC
2091	def_bool $(cc-option,-fsanitize-coverage=trace-pc)
2092
2093
2094config KCOV
2095	bool "Code coverage for fuzzing"
2096	depends on ARCH_HAS_KCOV
2097	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
2098	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
2099		   GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
2100	select DEBUG_FS
2101	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
2102	select OBJTOOL if HAVE_NOINSTR_HACK
2103	help
2104	  KCOV exposes kernel code coverage information in a form suitable
2105	  for coverage-guided fuzzing (randomized testing).
2106
2107	  If RANDOMIZE_BASE is enabled, PC values will not be stable across
2108	  different machines and across reboots. If you need stable PC values,
2109	  disable RANDOMIZE_BASE.
2110
2111	  For more details, see Documentation/dev-tools/kcov.rst.
2112
2113config KCOV_ENABLE_COMPARISONS
2114	bool "Enable comparison operands collection by KCOV"
2115	depends on KCOV
2116	depends on $(cc-option,-fsanitize-coverage=trace-cmp)
2117	help
2118	  KCOV also exposes operands of every comparison in the instrumented
2119	  code along with operand sizes and PCs of the comparison instructions.
2120	  These operands can be used by fuzzing engines to improve the quality
2121	  of fuzzing coverage.
2122
2123config KCOV_INSTRUMENT_ALL
2124	bool "Instrument all code by default"
2125	depends on KCOV
2126	default y
2127	help
2128	  If you are doing generic system call fuzzing (like e.g. syzkaller),
2129	  then you will want to instrument the whole kernel and you should
2130	  say y here. If you are doing more targeted fuzzing (like e.g.
2131	  filesystem fuzzing with AFL) then you will want to enable coverage
2132	  for more specific subsets of files, and should say n here.
2133
2134config KCOV_IRQ_AREA_SIZE
2135	hex "Size of interrupt coverage collection area in words"
2136	depends on KCOV
2137	default 0x40000
2138	help
2139	  KCOV uses preallocated per-cpu areas to collect coverage from
2140	  soft interrupts. This specifies the size of those areas in the
2141	  number of unsigned long words.
2142
2143menuconfig RUNTIME_TESTING_MENU
2144	bool "Runtime Testing"
2145	def_bool y
2146
2147if RUNTIME_TESTING_MENU
2148
2149config TEST_DHRY
2150	tristate "Dhrystone benchmark test"
2151	help
2152	  Enable this to include the Dhrystone 2.1 benchmark.  This test
2153	  calculates the number of Dhrystones per second, and the number of
2154	  DMIPS (Dhrystone MIPS) obtained when the Dhrystone score is divided
2155	  by 1757 (the number of Dhrystones per second obtained on the VAX
2156	  11/780, nominally a 1 MIPS machine).
2157
2158	  To run the benchmark, it needs to be enabled explicitly, either from
2159	  the kernel command line (when built-in), or from userspace (when
2160	  built-in or modular.
2161
2162	  Run once during kernel boot:
2163
2164	      test_dhry.run
2165
2166	  Set number of iterations from kernel command line:
2167
2168	      test_dhry.iterations=<n>
2169
2170	  Set number of iterations from userspace:
2171
2172	      echo <n> > /sys/module/test_dhry/parameters/iterations
2173
2174	  Trigger manual run from userspace:
2175
2176	      echo y > /sys/module/test_dhry/parameters/run
2177
2178	  If the number of iterations is <= 0, the test will devise a suitable
2179	  number of iterations (test runs for at least 2s) automatically.
2180	  This process takes ca. 4s.
2181
2182	  If unsure, say N.
2183
2184config LKDTM
2185	tristate "Linux Kernel Dump Test Tool Module"
2186	depends on DEBUG_FS
2187	help
2188	This module enables testing of the different dumping mechanisms by
2189	inducing system failures at predefined crash points.
2190	If you don't need it: say N
2191	Choose M here to compile this code as a module. The module will be
2192	called lkdtm.
2193
2194	Documentation on how to use the module can be found in
2195	Documentation/fault-injection/provoke-crashes.rst
2196
2197config CPUMASK_KUNIT_TEST
2198	tristate "KUnit test for cpumask" if !KUNIT_ALL_TESTS
2199	depends on KUNIT
2200	default KUNIT_ALL_TESTS
2201	help
2202	  Enable to turn on cpumask tests, running at boot or module load time.
2203
2204	  For more information on KUnit and unit tests in general, please refer
2205	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2206
2207	  If unsure, say N.
2208
2209config TEST_LIST_SORT
2210	tristate "Linked list sorting test" if !KUNIT_ALL_TESTS
2211	depends on KUNIT
2212	default KUNIT_ALL_TESTS
2213	help
2214	  Enable this to turn on 'list_sort()' function test. This test is
2215	  executed only once during system boot (so affects only boot time),
2216	  or at module load time.
2217
2218	  If unsure, say N.
2219
2220config TEST_MIN_HEAP
2221	tristate "Min heap test"
2222	depends on DEBUG_KERNEL || m
2223	help
2224	  Enable this to turn on min heap function tests. This test is
2225	  executed only once during system boot (so affects only boot time),
2226	  or at module load time.
2227
2228	  If unsure, say N.
2229
2230config TEST_SORT
2231	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
2232	depends on KUNIT
2233	default KUNIT_ALL_TESTS
2234	help
2235	  This option enables the self-test function of 'sort()' at boot,
2236	  or at module load time.
2237
2238	  If unsure, say N.
2239
2240config TEST_DIV64
2241	tristate "64bit/32bit division and modulo test"
2242	depends on DEBUG_KERNEL || m
2243	help
2244	  Enable this to turn on 'do_div()' function test. This test is
2245	  executed only once during system boot (so affects only boot time),
2246	  or at module load time.
2247
2248	  If unsure, say N.
2249
2250config TEST_IOV_ITER
2251	tristate "Test iov_iter operation" if !KUNIT_ALL_TESTS
2252	depends on KUNIT
2253	default KUNIT_ALL_TESTS
2254	help
2255	  Enable this to turn on testing of the operation of the I/O iterator
2256	  (iov_iter). This test is executed only once during system boot (so
2257	  affects only boot time), or at module load time.
2258
2259	  If unsure, say N.
2260
2261config KPROBES_SANITY_TEST
2262	tristate "Kprobes sanity tests" if !KUNIT_ALL_TESTS
2263	depends on DEBUG_KERNEL
2264	depends on KPROBES
2265	depends on KUNIT
2266	select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
2267	default KUNIT_ALL_TESTS
2268	help
2269	  This option provides for testing basic kprobes functionality on
2270	  boot. Samples of kprobe and kretprobe are inserted and
2271	  verified for functionality.
2272
2273	  Say N if you are unsure.
2274
2275config FPROBE_SANITY_TEST
2276	bool "Self test for fprobe"
2277	depends on DEBUG_KERNEL
2278	depends on FPROBE
2279	depends on KUNIT=y
2280	help
2281	  This option will enable testing the fprobe when the system boot.
2282	  A series of tests are made to verify that the fprobe is functioning
2283	  properly.
2284
2285	  Say N if you are unsure.
2286
2287config BACKTRACE_SELF_TEST
2288	tristate "Self test for the backtrace code"
2289	depends on DEBUG_KERNEL
2290	help
2291	  This option provides a kernel module that can be used to test
2292	  the kernel stack backtrace code. This option is not useful
2293	  for distributions or general kernels, but only for kernel
2294	  developers working on architecture code.
2295
2296	  Note that if you want to also test saved backtraces, you will
2297	  have to enable STACKTRACE as well.
2298
2299	  Say N if you are unsure.
2300
2301config TEST_REF_TRACKER
2302	tristate "Self test for reference tracker"
2303	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
2304	select REF_TRACKER
2305	help
2306	  This option provides a kernel module performing tests
2307	  using reference tracker infrastructure.
2308
2309	  Say N if you are unsure.
2310
2311config RBTREE_TEST
2312	tristate "Red-Black tree test"
2313	depends on DEBUG_KERNEL
2314	help
2315	  A benchmark measuring the performance of the rbtree library.
2316	  Also includes rbtree invariant checks.
2317
2318config REED_SOLOMON_TEST
2319	tristate "Reed-Solomon library test"
2320	depends on DEBUG_KERNEL || m
2321	select REED_SOLOMON
2322	select REED_SOLOMON_ENC16
2323	select REED_SOLOMON_DEC16
2324	help
2325	  This option enables the self-test function of rslib at boot,
2326	  or at module load time.
2327
2328	  If unsure, say N.
2329
2330config INTERVAL_TREE_TEST
2331	tristate "Interval tree test"
2332	depends on DEBUG_KERNEL
2333	select INTERVAL_TREE
2334	help
2335	  A benchmark measuring the performance of the interval tree library
2336
2337config PERCPU_TEST
2338	tristate "Per cpu operations test"
2339	depends on m && DEBUG_KERNEL
2340	help
2341	  Enable this option to build test module which validates per-cpu
2342	  operations.
2343
2344	  If unsure, say N.
2345
2346config ATOMIC64_SELFTEST
2347	tristate "Perform an atomic64_t self-test"
2348	help
2349	  Enable this option to test the atomic64_t functions at boot or
2350	  at module load time.
2351
2352	  If unsure, say N.
2353
2354config ASYNC_RAID6_TEST
2355	tristate "Self test for hardware accelerated raid6 recovery"
2356	depends on ASYNC_RAID6_RECOV
2357	select ASYNC_MEMCPY
2358	help
2359	  This is a one-shot self test that permutes through the
2360	  recovery of all the possible two disk failure scenarios for a
2361	  N-disk array.  Recovery is performed with the asynchronous
2362	  raid6 recovery routines, and will optionally use an offload
2363	  engine if one is available.
2364
2365	  If unsure, say N.
2366
2367config TEST_HEXDUMP
2368	tristate "Test functions located in the hexdump module at runtime"
2369
2370config STRING_SELFTEST
2371	tristate "Test string functions at runtime"
2372
2373config TEST_STRING_HELPERS
2374	tristate "Test functions located in the string_helpers module at runtime"
2375
2376config TEST_KSTRTOX
2377	tristate "Test kstrto*() family of functions at runtime"
2378
2379config TEST_PRINTF
2380	tristate "Test printf() family of functions at runtime"
2381
2382config TEST_SCANF
2383	tristate "Test scanf() family of functions at runtime"
2384
2385config TEST_BITMAP
2386	tristate "Test bitmap_*() family of functions at runtime"
2387	help
2388	  Enable this option to test the bitmap functions at boot.
2389
2390	  If unsure, say N.
2391
2392config TEST_UUID
2393	tristate "Test functions located in the uuid module at runtime"
2394
2395config TEST_XARRAY
2396	tristate "Test the XArray code at runtime"
2397
2398config TEST_MAPLE_TREE
2399	tristate "Test the Maple Tree code at runtime or module load"
2400	help
2401	  Enable this option to test the maple tree code functions at boot, or
2402	  when the module is loaded. Enable "Debug Maple Trees" will enable
2403	  more verbose output on failures.
2404
2405	  If unsure, say N.
2406
2407config TEST_RHASHTABLE
2408	tristate "Perform selftest on resizable hash table"
2409	help
2410	  Enable this option to test the rhashtable functions at boot.
2411
2412	  If unsure, say N.
2413
2414config TEST_IDA
2415	tristate "Perform selftest on IDA functions"
2416
2417config TEST_PARMAN
2418	tristate "Perform selftest on priority array manager"
2419	depends on PARMAN
2420	help
2421	  Enable this option to test priority array manager on boot
2422	  (or module load).
2423
2424	  If unsure, say N.
2425
2426config TEST_IRQ_TIMINGS
2427	bool "IRQ timings selftest"
2428	depends on IRQ_TIMINGS
2429	help
2430	  Enable this option to test the irq timings code on boot.
2431
2432	  If unsure, say N.
2433
2434config TEST_LKM
2435	tristate "Test module loading with 'hello world' module"
2436	depends on m
2437	help
2438	  This builds the "test_module" module that emits "Hello, world"
2439	  on printk when loaded. It is designed to be used for basic
2440	  evaluation of the module loading subsystem (for example when
2441	  validating module verification). It lacks any extra dependencies,
2442	  and will not normally be loaded by the system unless explicitly
2443	  requested by name.
2444
2445	  If unsure, say N.
2446
2447config TEST_BITOPS
2448	tristate "Test module for compilation of bitops operations"
2449	depends on m
2450	help
2451	  This builds the "test_bitops" module that is much like the
2452	  TEST_LKM module except that it does a basic exercise of the
2453	  set/clear_bit macros and get_count_order/long to make sure there are
2454	  no compiler warnings from C=1 sparse checker or -Wextra
2455	  compilations. It has no dependencies and doesn't run or load unless
2456	  explicitly requested by name.  for example: modprobe test_bitops.
2457
2458	  If unsure, say N.
2459
2460config TEST_VMALLOC
2461	tristate "Test module for stress/performance analysis of vmalloc allocator"
2462	default n
2463       depends on MMU
2464	depends on m
2465	help
2466	  This builds the "test_vmalloc" module that should be used for
2467	  stress and performance analysis. So, any new change for vmalloc
2468	  subsystem can be evaluated from performance and stability point
2469	  of view.
2470
2471	  If unsure, say N.
2472
2473config TEST_USER_COPY
2474	tristate "Test user/kernel boundary protections"
2475	depends on m
2476	help
2477	  This builds the "test_user_copy" module that runs sanity checks
2478	  on the copy_to/from_user infrastructure, making sure basic
2479	  user/kernel boundary testing is working. If it fails to load,
2480	  a regression has been detected in the user/kernel memory boundary
2481	  protections.
2482
2483	  If unsure, say N.
2484
2485config TEST_BPF
2486	tristate "Test BPF filter functionality"
2487	depends on m && NET
2488	help
2489	  This builds the "test_bpf" module that runs various test vectors
2490	  against the BPF interpreter or BPF JIT compiler depending on the
2491	  current setting. This is in particular useful for BPF JIT compiler
2492	  development, but also to run regression tests against changes in
2493	  the interpreter code. It also enables test stubs for eBPF maps and
2494	  verifier used by user space verifier testsuite.
2495
2496	  If unsure, say N.
2497
2498config TEST_BLACKHOLE_DEV
2499	tristate "Test blackhole netdev functionality"
2500	depends on m && NET
2501	help
2502	  This builds the "test_blackhole_dev" module that validates the
2503	  data path through this blackhole netdev.
2504
2505	  If unsure, say N.
2506
2507config FIND_BIT_BENCHMARK
2508	tristate "Test find_bit functions"
2509	help
2510	  This builds the "test_find_bit" module that measure find_*_bit()
2511	  functions performance.
2512
2513	  If unsure, say N.
2514
2515config TEST_FIRMWARE
2516	tristate "Test firmware loading via userspace interface"
2517	depends on FW_LOADER
2518	help
2519	  This builds the "test_firmware" module that creates a userspace
2520	  interface for testing firmware loading. This can be used to
2521	  control the triggering of firmware loading without needing an
2522	  actual firmware-using device. The contents can be rechecked by
2523	  userspace.
2524
2525	  If unsure, say N.
2526
2527config TEST_SYSCTL
2528	tristate "sysctl test driver"
2529	depends on PROC_SYSCTL
2530	help
2531	  This builds the "test_sysctl" module. This driver enables to test the
2532	  proc sysctl interfaces available to drivers safely without affecting
2533	  production knobs which might alter system functionality.
2534
2535	  If unsure, say N.
2536
2537config BITFIELD_KUNIT
2538	tristate "KUnit test bitfield functions at runtime" if !KUNIT_ALL_TESTS
2539	depends on KUNIT
2540	default KUNIT_ALL_TESTS
2541	help
2542	  Enable this option to test the bitfield functions at boot.
2543
2544	  KUnit tests run during boot and output the results to the debug log
2545	  in TAP format (http://testanything.org/). Only useful for kernel devs
2546	  running the KUnit test harness, and not intended for inclusion into a
2547	  production build.
2548
2549	  For more information on KUnit and unit tests in general please refer
2550	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2551
2552	  If unsure, say N.
2553
2554config CHECKSUM_KUNIT
2555	tristate "KUnit test checksum functions at runtime" if !KUNIT_ALL_TESTS
2556	depends on KUNIT
2557	default KUNIT_ALL_TESTS
2558	help
2559	  Enable this option to test the checksum functions at boot.
2560
2561	  KUnit tests run during boot and output the results to the debug log
2562	  in TAP format (http://testanything.org/). Only useful for kernel devs
2563	  running the KUnit test harness, and not intended for inclusion into a
2564	  production build.
2565
2566	  For more information on KUnit and unit tests in general please refer
2567	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2568
2569	  If unsure, say N.
2570
2571config HASH_KUNIT_TEST
2572	tristate "KUnit Test for integer hash functions" if !KUNIT_ALL_TESTS
2573	depends on KUNIT
2574	default KUNIT_ALL_TESTS
2575	help
2576	  Enable this option to test the kernel's string (<linux/stringhash.h>), and
2577	  integer (<linux/hash.h>) hash functions on boot.
2578
2579	  KUnit tests run during boot and output the results to the debug log
2580	  in TAP format (https://testanything.org/). Only useful for kernel devs
2581	  running the KUnit test harness, and not intended for inclusion into a
2582	  production build.
2583
2584	  For more information on KUnit and unit tests in general please refer
2585	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2586
2587	  This is intended to help people writing architecture-specific
2588	  optimized versions. If unsure, say N.
2589
2590config RESOURCE_KUNIT_TEST
2591	tristate "KUnit test for resource API" if !KUNIT_ALL_TESTS
2592	depends on KUNIT
2593	default KUNIT_ALL_TESTS
2594	help
2595	  This builds the resource API unit test.
2596	  Tests the logic of API provided by resource.c and ioport.h.
2597	  For more information on KUnit and unit tests in general please refer
2598	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2599
2600	  If unsure, say N.
2601
2602config SYSCTL_KUNIT_TEST
2603	tristate "KUnit test for sysctl" if !KUNIT_ALL_TESTS
2604	depends on KUNIT
2605	default KUNIT_ALL_TESTS
2606	help
2607	  This builds the proc sysctl unit test, which runs on boot.
2608	  Tests the API contract and implementation correctness of sysctl.
2609	  For more information on KUnit and unit tests in general please refer
2610	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2611
2612	  If unsure, say N.
2613
2614config LIST_KUNIT_TEST
2615	tristate "KUnit Test for Kernel Linked-list structures" if !KUNIT_ALL_TESTS
2616	depends on KUNIT
2617	default KUNIT_ALL_TESTS
2618	help
2619	  This builds the linked list KUnit test suite.
2620	  It tests that the API and basic functionality of the list_head type
2621	  and associated macros.
2622
2623	  KUnit tests run during boot and output the results to the debug log
2624	  in TAP format (https://testanything.org/). Only useful for kernel devs
2625	  running the KUnit test harness, and not intended for inclusion into a
2626	  production build.
2627
2628	  For more information on KUnit and unit tests in general please refer
2629	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2630
2631	  If unsure, say N.
2632
2633config HASHTABLE_KUNIT_TEST
2634	tristate "KUnit Test for Kernel Hashtable structures" if !KUNIT_ALL_TESTS
2635	depends on KUNIT
2636	default KUNIT_ALL_TESTS
2637	help
2638	  This builds the hashtable KUnit test suite.
2639	  It tests the basic functionality of the API defined in
2640	  include/linux/hashtable.h. For more information on KUnit and
2641	  unit tests in general please refer to the KUnit documentation
2642	  in Documentation/dev-tools/kunit/.
2643
2644	  If unsure, say N.
2645
2646config LINEAR_RANGES_TEST
2647	tristate "KUnit test for linear_ranges"
2648	depends on KUNIT
2649	select LINEAR_RANGES
2650	help
2651	  This builds the linear_ranges unit test, which runs on boot.
2652	  Tests the linear_ranges logic correctness.
2653	  For more information on KUnit and unit tests in general please refer
2654	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2655
2656	  If unsure, say N.
2657
2658config CMDLINE_KUNIT_TEST
2659	tristate "KUnit test for cmdline API" if !KUNIT_ALL_TESTS
2660	depends on KUNIT
2661	default KUNIT_ALL_TESTS
2662	help
2663	  This builds the cmdline API unit test.
2664	  Tests the logic of API provided by cmdline.c.
2665	  For more information on KUnit and unit tests in general please refer
2666	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2667
2668	  If unsure, say N.
2669
2670config BITS_TEST
2671	tristate "KUnit test for bits.h" if !KUNIT_ALL_TESTS
2672	depends on KUNIT
2673	default KUNIT_ALL_TESTS
2674	help
2675	  This builds the bits unit test.
2676	  Tests the logic of macros defined in bits.h.
2677	  For more information on KUnit and unit tests in general please refer
2678	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2679
2680	  If unsure, say N.
2681
2682config SLUB_KUNIT_TEST
2683	tristate "KUnit test for SLUB cache error detection" if !KUNIT_ALL_TESTS
2684	depends on SLUB_DEBUG && KUNIT
2685	default KUNIT_ALL_TESTS
2686	help
2687	  This builds SLUB allocator unit test.
2688	  Tests SLUB cache debugging functionality.
2689	  For more information on KUnit and unit tests in general please refer
2690	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2691
2692	  If unsure, say N.
2693
2694config RATIONAL_KUNIT_TEST
2695	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
2696	depends on KUNIT && RATIONAL
2697	default KUNIT_ALL_TESTS
2698	help
2699	  This builds the rational math unit test.
2700	  For more information on KUnit and unit tests in general please refer
2701	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2702
2703	  If unsure, say N.
2704
2705config MEMCPY_KUNIT_TEST
2706	tristate "Test memcpy(), memmove(), and memset() functions at runtime" if !KUNIT_ALL_TESTS
2707	depends on KUNIT
2708	default KUNIT_ALL_TESTS
2709	help
2710	  Builds unit tests for memcpy(), memmove(), and memset() functions.
2711	  For more information on KUnit and unit tests in general please refer
2712	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2713
2714	  If unsure, say N.
2715
2716config MEMCPY_SLOW_KUNIT_TEST
2717	bool "Include exhaustive memcpy tests"
2718	depends on MEMCPY_KUNIT_TEST
2719	default y
2720	help
2721	  Some memcpy tests are quite exhaustive in checking for overlaps
2722	  and bit ranges. These can be very slow, so they are split out
2723	  as a separate config, in case they need to be disabled.
2724
2725	  Note this config option will be replaced by the use of KUnit test
2726	  attributes.
2727
2728config IS_SIGNED_TYPE_KUNIT_TEST
2729	tristate "Test is_signed_type() macro" if !KUNIT_ALL_TESTS
2730	depends on KUNIT
2731	default KUNIT_ALL_TESTS
2732	help
2733	  Builds unit tests for the is_signed_type() macro.
2734
2735	  For more information on KUnit and unit tests in general please refer
2736	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2737
2738	  If unsure, say N.
2739
2740config OVERFLOW_KUNIT_TEST
2741	tristate "Test check_*_overflow() functions at runtime" if !KUNIT_ALL_TESTS
2742	depends on KUNIT
2743	default KUNIT_ALL_TESTS
2744	help
2745	  Builds unit tests for the check_*_overflow(), size_*(), allocation, and
2746	  related functions.
2747
2748	  For more information on KUnit and unit tests in general please refer
2749	  to the KUnit documentation in Documentation/dev-tools/kunit/.
2750
2751	  If unsure, say N.
2752
2753config STACKINIT_KUNIT_TEST
2754	tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS
2755	depends on KUNIT
2756	default KUNIT_ALL_TESTS
2757	help
2758	  Test if the kernel is zero-initializing stack variables and
2759	  padding. Coverage is controlled by compiler flags,
2760	  CONFIG_INIT_STACK_ALL_PATTERN, CONFIG_INIT_STACK_ALL_ZERO,
2761	  CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF,
2762	  or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL.
2763
2764config FORTIFY_KUNIT_TEST
2765	tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS
2766	depends on KUNIT && FORTIFY_SOURCE
2767	default KUNIT_ALL_TESTS
2768	help
2769	  Builds unit tests for checking internals of FORTIFY_SOURCE as used
2770	  by the str*() and mem*() family of functions. For testing runtime
2771	  traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests.
2772
2773config HW_BREAKPOINT_KUNIT_TEST
2774	bool "Test hw_breakpoint constraints accounting" if !KUNIT_ALL_TESTS
2775	depends on HAVE_HW_BREAKPOINT
2776	depends on KUNIT=y
2777	default KUNIT_ALL_TESTS
2778	help
2779	  Tests for hw_breakpoint constraints accounting.
2780
2781	  If unsure, say N.
2782
2783config STRCAT_KUNIT_TEST
2784	tristate "Test strcat() family of functions at runtime" if !KUNIT_ALL_TESTS
2785	depends on KUNIT
2786	default KUNIT_ALL_TESTS
2787
2788config STRSCPY_KUNIT_TEST
2789	tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
2790	depends on KUNIT
2791	default KUNIT_ALL_TESTS
2792
2793config SIPHASH_KUNIT_TEST
2794	tristate "Perform selftest on siphash functions" if !KUNIT_ALL_TESTS
2795	depends on KUNIT
2796	default KUNIT_ALL_TESTS
2797	help
2798	  Enable this option to test the kernel's siphash (<linux/siphash.h>) hash
2799	  functions on boot (or module load).
2800
2801	  This is intended to help people writing architecture-specific
2802	  optimized versions.  If unsure, say N.
2803
2804config TEST_UDELAY
2805	tristate "udelay test driver"
2806	help
2807	  This builds the "udelay_test" module that helps to make sure
2808	  that udelay() is working properly.
2809
2810	  If unsure, say N.
2811
2812config TEST_STATIC_KEYS
2813	tristate "Test static keys"
2814	depends on m
2815	help
2816	  Test the static key interfaces.
2817
2818	  If unsure, say N.
2819
2820config TEST_DYNAMIC_DEBUG
2821	tristate "Test DYNAMIC_DEBUG"
2822	depends on DYNAMIC_DEBUG
2823	help
2824	  This module registers a tracer callback to count enabled
2825	  pr_debugs in a 'do_debugging' function, then alters their
2826	  enablements, calls the function, and compares counts.
2827
2828	  If unsure, say N.
2829
2830config TEST_KMOD
2831	tristate "kmod stress tester"
2832	depends on m
2833	depends on NETDEVICES && NET_CORE && INET # for TUN
2834	depends on BLOCK
2835	depends on PAGE_SIZE_LESS_THAN_256KB # for BTRFS
2836	select TEST_LKM
2837	select XFS_FS
2838	select TUN
2839	select BTRFS_FS
2840	help
2841	  Test the kernel's module loading mechanism: kmod. kmod implements
2842	  support to load modules using the Linux kernel's usermode helper.
2843	  This test provides a series of tests against kmod.
2844
2845	  Although technically you can either build test_kmod as a module or
2846	  into the kernel we disallow building it into the kernel since
2847	  it stress tests request_module() and this will very likely cause
2848	  some issues by taking over precious threads available from other
2849	  module load requests, ultimately this could be fatal.
2850
2851	  To run tests run:
2852
2853	  tools/testing/selftests/kmod/kmod.sh --help
2854
2855	  If unsure, say N.
2856
2857config TEST_DEBUG_VIRTUAL
2858	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
2859	depends on DEBUG_VIRTUAL
2860	help
2861	  Test the kernel's ability to detect incorrect calls to
2862	  virt_to_phys() done against the non-linear part of the
2863	  kernel's virtual address map.
2864
2865	  If unsure, say N.
2866
2867config TEST_MEMCAT_P
2868	tristate "Test memcat_p() helper function"
2869	help
2870	  Test the memcat_p() helper for correctly merging two
2871	  pointer arrays together.
2872
2873	  If unsure, say N.
2874
2875config TEST_LIVEPATCH
2876	tristate "Test livepatching"
2877	default n
2878	depends on DYNAMIC_DEBUG
2879	depends on LIVEPATCH
2880	depends on m
2881	help
2882	  Test kernel livepatching features for correctness.  The tests will
2883	  load test modules that will be livepatched in various scenarios.
2884
2885	  To run all the livepatching tests:
2886
2887	  make -C tools/testing/selftests TARGETS=livepatch run_tests
2888
2889	  Alternatively, individual tests may be invoked:
2890
2891	  tools/testing/selftests/livepatch/test-callbacks.sh
2892	  tools/testing/selftests/livepatch/test-livepatch.sh
2893	  tools/testing/selftests/livepatch/test-shadow-vars.sh
2894
2895	  If unsure, say N.
2896
2897config TEST_OBJAGG
2898	tristate "Perform selftest on object aggreration manager"
2899	default n
2900	depends on OBJAGG
2901	help
2902	  Enable this option to test object aggregation manager on boot
2903	  (or module load).
2904
2905config TEST_MEMINIT
2906	tristate "Test heap/page initialization"
2907	help
2908	  Test if the kernel is zero-initializing heap and page allocations.
2909	  This can be useful to test init_on_alloc and init_on_free features.
2910
2911	  If unsure, say N.
2912
2913config TEST_HMM
2914	tristate "Test HMM (Heterogeneous Memory Management)"
2915	depends on TRANSPARENT_HUGEPAGE
2916	depends on DEVICE_PRIVATE
2917	select HMM_MIRROR
2918	select MMU_NOTIFIER
2919	help
2920	  This is a pseudo device driver solely for testing HMM.
2921	  Say M here if you want to build the HMM test module.
2922	  Doing so will allow you to run tools/testing/selftest/vm/hmm-tests.
2923
2924	  If unsure, say N.
2925
2926config TEST_FREE_PAGES
2927	tristate "Test freeing pages"
2928	help
2929	  Test that a memory leak does not occur due to a race between
2930	  freeing a block of pages and a speculative page reference.
2931	  Loading this module is safe if your kernel has the bug fixed.
2932	  If the bug is not fixed, it will leak gigabytes of memory and
2933	  probably OOM your system.
2934
2935config TEST_FPU
2936	tristate "Test floating point operations in kernel space"
2937	depends on X86 && !KCOV_INSTRUMENT_ALL
2938	help
2939	  Enable this option to add /sys/kernel/debug/selftest_helpers/test_fpu
2940	  which will trigger a sequence of floating point operations. This is used
2941	  for self-testing floating point control register setting in
2942	  kernel_fpu_begin().
2943
2944	  If unsure, say N.
2945
2946config TEST_CLOCKSOURCE_WATCHDOG
2947	tristate "Test clocksource watchdog in kernel space"
2948	depends on CLOCKSOURCE_WATCHDOG
2949	help
2950	  Enable this option to create a kernel module that will trigger
2951	  a test of the clocksource watchdog.  This module may be loaded
2952	  via modprobe or insmod in which case it will run upon being
2953	  loaded, or it may be built in, in which case it will run
2954	  shortly after boot.
2955
2956	  If unsure, say N.
2957
2958config TEST_OBJPOOL
2959	tristate "Test module for correctness and stress of objpool"
2960	default n
2961	depends on m && DEBUG_KERNEL
2962	help
2963	  This builds the "test_objpool" module that should be used for
2964	  correctness verification and concurrent testings of objects
2965	  allocation and reclamation.
2966
2967	  If unsure, say N.
2968
2969endif # RUNTIME_TESTING_MENU
2970
2971config ARCH_USE_MEMTEST
2972	bool
2973	help
2974	  An architecture should select this when it uses early_memtest()
2975	  during boot process.
2976
2977config MEMTEST
2978	bool "Memtest"
2979	depends on ARCH_USE_MEMTEST
2980	help
2981	  This option adds a kernel parameter 'memtest', which allows memtest
2982	  to be set and executed.
2983	        memtest=0, mean disabled; -- default
2984	        memtest=1, mean do 1 test pattern;
2985	        ...
2986	        memtest=17, mean do 17 test patterns.
2987	  If you are unsure how to answer this question, answer N.
2988
2989
2990
2991config HYPERV_TESTING
2992	bool "Microsoft Hyper-V driver testing"
2993	default n
2994	depends on HYPERV && DEBUG_FS
2995	help
2996	  Select this option to enable Hyper-V vmbus testing.
2997
2998endmenu # "Kernel Testing and Coverage"
2999
3000menu "Rust hacking"
3001
3002config RUST_DEBUG_ASSERTIONS
3003	bool "Debug assertions"
3004	depends on RUST
3005	help
3006	  Enables rustc's `-Cdebug-assertions` codegen option.
3007
3008	  This flag lets you turn `cfg(debug_assertions)` conditional
3009	  compilation on or off. This can be used to enable extra debugging
3010	  code in development but not in production. For example, it controls
3011	  the behavior of the standard library's `debug_assert!` macro.
3012
3013	  Note that this will apply to all Rust code, including `core`.
3014
3015	  If unsure, say N.
3016
3017config RUST_OVERFLOW_CHECKS
3018	bool "Overflow checks"
3019	default y
3020	depends on RUST
3021	help
3022	  Enables rustc's `-Coverflow-checks` codegen option.
3023
3024	  This flag allows you to control the behavior of runtime integer
3025	  overflow. When overflow-checks are enabled, a Rust panic will occur
3026	  on overflow.
3027
3028	  Note that this will apply to all Rust code, including `core`.
3029
3030	  If unsure, say Y.
3031
3032config RUST_BUILD_ASSERT_ALLOW
3033	bool "Allow unoptimized build-time assertions"
3034	depends on RUST
3035	help
3036	  Controls how are `build_error!` and `build_assert!` handled during build.
3037
3038	  If calls to them exist in the binary, it may indicate a violated invariant
3039	  or that the optimizer failed to verify the invariant during compilation.
3040
3041	  This should not happen, thus by default the build is aborted. However,
3042	  as an escape hatch, you can choose Y here to ignore them during build
3043	  and let the check be carried at runtime (with `panic!` being called if
3044	  the check fails).
3045
3046	  If unsure, say N.
3047
3048config RUST_KERNEL_DOCTESTS
3049	bool "Doctests for the `kernel` crate" if !KUNIT_ALL_TESTS
3050	depends on RUST && KUNIT=y
3051	default KUNIT_ALL_TESTS
3052	help
3053	  This builds the documentation tests of the `kernel` crate
3054	  as KUnit tests.
3055
3056	  For more information on KUnit and unit tests in general,
3057	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
3058
3059	  If unsure, say N.
3060
3061endmenu # "Rust"
3062
3063endmenu # Kernel hacking
3064